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serve_forever(poll_interval=0.5)
Handle requests until an explicit shutdown() request. Poll for shutdown every poll_interval seconds. Ignores the timeout attribute. It also calls service_actions(), which may be used by a subclass or mixin to provide actions specific to a given service. For example, the ForkingMixIn class uses service_actions() to clean up zombie child processes. Changed in version 3.3: Added service_actions call to the serve_forever method. | python.library.socketserver#socketserver.BaseServer.serve_forever |
service_actions()
This is called in the serve_forever() loop. This method can be overridden by subclasses or mixin classes to perform actions specific to a given service, such as cleanup actions. New in version 3.3. | python.library.socketserver#socketserver.BaseServer.service_actions |
shutdown()
Tell the serve_forever() loop to stop and wait until it does. shutdown() must be called while serve_forever() is running in a different thread otherwise it will deadlock. | python.library.socketserver#socketserver.BaseServer.shutdown |
socket
The socket object on which the server will listen for incoming requests. | python.library.socketserver#socketserver.BaseServer.socket |
socket_type
The type of socket used by the server; socket.SOCK_STREAM and socket.SOCK_DGRAM are two common values. | python.library.socketserver#socketserver.BaseServer.socket_type |
timeout
Timeout duration, measured in seconds, or None if no timeout is desired. If handle_request() receives no incoming requests within the timeout period, the handle_timeout() method is called. | python.library.socketserver#socketserver.BaseServer.timeout |
verify_request(request, client_address)
Must return a Boolean value; if the value is True, the request will be processed, and if it’s False, the request will be denied. This function can be overridden to implement access controls for a server. The default implementation always returns True. | python.library.socketserver#socketserver.BaseServer.verify_request |
class socketserver.StreamRequestHandler
class socketserver.DatagramRequestHandler
These BaseRequestHandler subclasses override the setup() and finish() methods, and provide self.rfile and self.wfile attributes. The self.rfile and self.wfile attributes can be read or written, respectively, to get the request data or return data to the client. The rfile attributes of both classes support the io.BufferedIOBase readable interface, and DatagramRequestHandler.wfile supports the io.BufferedIOBase writable interface. Changed in version 3.6: StreamRequestHandler.wfile also supports the io.BufferedIOBase writable interface. | python.library.socketserver#socketserver.DatagramRequestHandler |
class socketserver.ForkingMixIn
class socketserver.ThreadingMixIn
Forking and threading versions of each type of server can be created using these mix-in classes. For instance, ThreadingUDPServer is created as follows: class ThreadingUDPServer(ThreadingMixIn, UDPServer):
pass
The mix-in class comes first, since it overrides a method defined in UDPServer. Setting the various attributes also changes the behavior of the underlying server mechanism. ForkingMixIn and the Forking classes mentioned below are only available on POSIX platforms that support fork(). socketserver.ForkingMixIn.server_close() waits until all child processes complete, except if socketserver.ForkingMixIn.block_on_close attribute is false. socketserver.ThreadingMixIn.server_close() waits until all non-daemon threads complete, except if socketserver.ThreadingMixIn.block_on_close attribute is false. Use daemonic threads by setting ThreadingMixIn.daemon_threads to True to not wait until threads complete. Changed in version 3.7: socketserver.ForkingMixIn.server_close() and socketserver.ThreadingMixIn.server_close() now waits until all child processes and non-daemonic threads complete. Add a new socketserver.ForkingMixIn.block_on_close class attribute to opt-in for the pre-3.7 behaviour. | python.library.socketserver#socketserver.ForkingMixIn |
class socketserver.ForkingTCPServer
class socketserver.ForkingUDPServer
class socketserver.ThreadingTCPServer
class socketserver.ThreadingUDPServer
These classes are pre-defined using the mix-in classes. | python.library.socketserver#socketserver.ForkingTCPServer |
class socketserver.ForkingTCPServer
class socketserver.ForkingUDPServer
class socketserver.ThreadingTCPServer
class socketserver.ThreadingUDPServer
These classes are pre-defined using the mix-in classes. | python.library.socketserver#socketserver.ForkingUDPServer |
class socketserver.StreamRequestHandler
class socketserver.DatagramRequestHandler
These BaseRequestHandler subclasses override the setup() and finish() methods, and provide self.rfile and self.wfile attributes. The self.rfile and self.wfile attributes can be read or written, respectively, to get the request data or return data to the client. The rfile attributes of both classes support the io.BufferedIOBase readable interface, and DatagramRequestHandler.wfile supports the io.BufferedIOBase writable interface. Changed in version 3.6: StreamRequestHandler.wfile also supports the io.BufferedIOBase writable interface. | python.library.socketserver#socketserver.StreamRequestHandler |
class socketserver.TCPServer(server_address, RequestHandlerClass, bind_and_activate=True)
This uses the Internet TCP protocol, which provides for continuous streams of data between the client and server. If bind_and_activate is true, the constructor automatically attempts to invoke server_bind() and server_activate(). The other parameters are passed to the BaseServer base class. | python.library.socketserver#socketserver.TCPServer |
class socketserver.ForkingMixIn
class socketserver.ThreadingMixIn
Forking and threading versions of each type of server can be created using these mix-in classes. For instance, ThreadingUDPServer is created as follows: class ThreadingUDPServer(ThreadingMixIn, UDPServer):
pass
The mix-in class comes first, since it overrides a method defined in UDPServer. Setting the various attributes also changes the behavior of the underlying server mechanism. ForkingMixIn and the Forking classes mentioned below are only available on POSIX platforms that support fork(). socketserver.ForkingMixIn.server_close() waits until all child processes complete, except if socketserver.ForkingMixIn.block_on_close attribute is false. socketserver.ThreadingMixIn.server_close() waits until all non-daemon threads complete, except if socketserver.ThreadingMixIn.block_on_close attribute is false. Use daemonic threads by setting ThreadingMixIn.daemon_threads to True to not wait until threads complete. Changed in version 3.7: socketserver.ForkingMixIn.server_close() and socketserver.ThreadingMixIn.server_close() now waits until all child processes and non-daemonic threads complete. Add a new socketserver.ForkingMixIn.block_on_close class attribute to opt-in for the pre-3.7 behaviour. | python.library.socketserver#socketserver.ThreadingMixIn |
class socketserver.ForkingTCPServer
class socketserver.ForkingUDPServer
class socketserver.ThreadingTCPServer
class socketserver.ThreadingUDPServer
These classes are pre-defined using the mix-in classes. | python.library.socketserver#socketserver.ThreadingTCPServer |
class socketserver.ForkingTCPServer
class socketserver.ForkingUDPServer
class socketserver.ThreadingTCPServer
class socketserver.ThreadingUDPServer
These classes are pre-defined using the mix-in classes. | python.library.socketserver#socketserver.ThreadingUDPServer |
class socketserver.UDPServer(server_address, RequestHandlerClass, bind_and_activate=True)
This uses datagrams, which are discrete packets of information that may arrive out of order or be lost while in transit. The parameters are the same as for TCPServer. | python.library.socketserver#socketserver.UDPServer |
class socketserver.UnixStreamServer(server_address, RequestHandlerClass, bind_and_activate=True)
class socketserver.UnixDatagramServer(server_address, RequestHandlerClass, bind_and_activate=True)
These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they’re not available on non-Unix platforms. The parameters are the same as for TCPServer. | python.library.socketserver#socketserver.UnixDatagramServer |
class socketserver.UnixStreamServer(server_address, RequestHandlerClass, bind_and_activate=True)
class socketserver.UnixDatagramServer(server_address, RequestHandlerClass, bind_and_activate=True)
These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they’re not available on non-Unix platforms. The parameters are the same as for TCPServer. | python.library.socketserver#socketserver.UnixStreamServer |
sorted(iterable, *, key=None, reverse=False)
Return a new sorted list from the items in iterable. Has two optional arguments which must be specified as keyword arguments. key specifies a function of one argument that is used to extract a comparison key from each element in iterable (for example, key=str.lower). The default value is None (compare the elements directly). reverse is a boolean value. If set to True, then the list elements are sorted as if each comparison were reversed. Use functools.cmp_to_key() to convert an old-style cmp function to a key function. The built-in sorted() function is guaranteed to be stable. A sort is stable if it guarantees not to change the relative order of elements that compare equal — this is helpful for sorting in multiple passes (for example, sort by department, then by salary grade). For sorting examples and a brief sorting tutorial, see Sorting HOW TO. | python.library.functions#sorted |
spwd — The shadow password database This module provides access to the Unix shadow password database. It is available on various Unix versions. You must have enough privileges to access the shadow password database (this usually means you have to be root). Shadow password database entries are reported as a tuple-like object, whose attributes correspond to the members of the spwd structure (Attribute field below, see <shadow.h>):
Index Attribute Meaning
0 sp_namp Login name
1 sp_pwdp Encrypted password
2 sp_lstchg Date of last change
3 sp_min Minimal number of days between changes
4 sp_max Maximum number of days between changes
5 sp_warn Number of days before password expires to warn user about it
6 sp_inact Number of days after password expires until account is disabled
7 sp_expire Number of days since 1970-01-01 when account expires
8 sp_flag Reserved The sp_namp and sp_pwdp items are strings, all others are integers. KeyError is raised if the entry asked for cannot be found. The following functions are defined:
spwd.getspnam(name)
Return the shadow password database entry for the given user name. Changed in version 3.6: Raises a PermissionError instead of KeyError if the user doesn’t have privileges.
spwd.getspall()
Return a list of all available shadow password database entries, in arbitrary order.
See also
Module grp
An interface to the group database, similar to this.
Module pwd
An interface to the normal password database, similar to this. | python.library.spwd |
spwd.getspall()
Return a list of all available shadow password database entries, in arbitrary order. | python.library.spwd#spwd.getspall |
spwd.getspnam(name)
Return the shadow password database entry for the given user name. Changed in version 3.6: Raises a PermissionError instead of KeyError if the user doesn’t have privileges. | python.library.spwd#spwd.getspnam |
sqlite3 — DB-API 2.0 interface for SQLite databases Source code: Lib/sqlite3/ SQLite is a C library that provides a lightweight disk-based database that doesn’t require a separate server process and allows accessing the database using a nonstandard variant of the SQL query language. Some applications can use SQLite for internal data storage. It’s also possible to prototype an application using SQLite and then port the code to a larger database such as PostgreSQL or Oracle. The sqlite3 module was written by Gerhard Häring. It provides a SQL interface compliant with the DB-API 2.0 specification described by PEP 249. To use the module, you must first create a Connection object that represents the database. Here the data will be stored in the example.db file: import sqlite3
con = sqlite3.connect('example.db')
You can also supply the special name :memory: to create a database in RAM. Once you have a Connection, you can create a Cursor object and call its execute() method to perform SQL commands: cur = con.cursor()
# Create table
cur.execute('''CREATE TABLE stocks
(date text, trans text, symbol text, qty real, price real)''')
# Insert a row of data
cur.execute("INSERT INTO stocks VALUES ('2006-01-05','BUY','RHAT',100,35.14)")
# Save (commit) the changes
con.commit()
# We can also close the connection if we are done with it.
# Just be sure any changes have been committed or they will be lost.
con.close()
The data you’ve saved is persistent and is available in subsequent sessions: import sqlite3
con = sqlite3.connect('example.db')
cur = con.cursor()
To retrieve data after executing a SELECT statement, you can either treat the cursor as an iterator, call the cursor’s fetchone() method to retrieve a single matching row, or call fetchall() to get a list of the matching rows. This example uses the iterator form: >>> for row in cur.execute('SELECT * FROM stocks ORDER BY price'):
print(row)
('2006-01-05', 'BUY', 'RHAT', 100, 35.14)
('2006-03-28', 'BUY', 'IBM', 1000, 45.0)
('2006-04-06', 'SELL', 'IBM', 500, 53.0)
('2006-04-05', 'BUY', 'MSFT', 1000, 72.0)
Usually your SQL operations will need to use values from Python variables. You shouldn’t assemble your query using Python’s string operations because doing so is insecure; it makes your program vulnerable to an SQL injection attack (see the xkcd webcomic for a humorous example of what can go wrong): # Never do this -- insecure!
symbol = 'RHAT'
cur.execute("SELECT * FROM stocks WHERE symbol = '%s'" % symbol)
Instead, use the DB-API’s parameter substitution. Put a placeholder wherever you want to use a value, and then provide a tuple of values as the second argument to the cursor’s execute() method. An SQL statement may use one of two kinds of placeholders: question marks (qmark style) or named placeholders (named style). For the qmark style, parameters must be a sequence. For the named style, it can be either a sequence or dict instance. The length of the sequence must match the number of placeholders, or a ProgrammingError is raised. If a dict is given, it must contain keys for all named parameters. Any extra items are ignored. Here’s an example of both styles: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table lang (lang_name, lang_age)")
# This is the qmark style:
cur.execute("insert into lang values (?, ?)", ("C", 49))
# The qmark style used with executemany():
lang_list = [
("Fortran", 64),
("Python", 30),
("Go", 11),
]
cur.executemany("insert into lang values (?, ?)", lang_list)
# And this is the named style:
cur.execute("select * from lang where lang_name=:name and lang_age=:age",
{"name": "C", "age": 49})
print(cur.fetchall())
con.close()
See also https://www.sqlite.org
The SQLite web page; the documentation describes the syntax and the available data types for the supported SQL dialect. https://www.w3schools.com/sql/
Tutorial, reference and examples for learning SQL syntax.
PEP 249 - Database API Specification 2.0
PEP written by Marc-André Lemburg. Module functions and constants
sqlite3.version
The version number of this module, as a string. This is not the version of the SQLite library.
sqlite3.version_info
The version number of this module, as a tuple of integers. This is not the version of the SQLite library.
sqlite3.sqlite_version
The version number of the run-time SQLite library, as a string.
sqlite3.sqlite_version_info
The version number of the run-time SQLite library, as a tuple of integers.
sqlite3.PARSE_DECLTYPES
This constant is meant to be used with the detect_types parameter of the connect() function. Setting it makes the sqlite3 module parse the declared type for each column it returns. It will parse out the first word of the declared type, i. e. for “integer primary key”, it will parse out “integer”, or for “number(10)” it will parse out “number”. Then for that column, it will look into the converters dictionary and use the converter function registered for that type there.
sqlite3.PARSE_COLNAMES
This constant is meant to be used with the detect_types parameter of the connect() function. Setting this makes the SQLite interface parse the column name for each column it returns. It will look for a string formed [mytype] in there, and then decide that ‘mytype’ is the type of the column. It will try to find an entry of ‘mytype’ in the converters dictionary and then use the converter function found there to return the value. The column name found in Cursor.description does not include the type, i. e. if you use something like 'as "Expiration date [datetime]"' in your SQL, then we will parse out everything until the first '[' for the column name and strip the preceeding space: the column name would simply be “Expiration date”.
sqlite3.connect(database[, timeout, detect_types, isolation_level, check_same_thread, factory, cached_statements, uri])
Opens a connection to the SQLite database file database. By default returns a Connection object, unless a custom factory is given. database is a path-like object giving the pathname (absolute or relative to the current working directory) of the database file to be opened. You can use ":memory:" to open a database connection to a database that resides in RAM instead of on disk. When a database is accessed by multiple connections, and one of the processes modifies the database, the SQLite database is locked until that transaction is committed. The timeout parameter specifies how long the connection should wait for the lock to go away until raising an exception. The default for the timeout parameter is 5.0 (five seconds). For the isolation_level parameter, please see the isolation_level property of Connection objects. SQLite natively supports only the types TEXT, INTEGER, REAL, BLOB and NULL. If you want to use other types you must add support for them yourself. The detect_types parameter and the using custom converters registered with the module-level register_converter() function allow you to easily do that. detect_types defaults to 0 (i. e. off, no type detection), you can set it to any combination of PARSE_DECLTYPES and PARSE_COLNAMES to turn type detection on. Due to SQLite behaviour, types can’t be detected for generated fields (for example max(data)), even when detect_types parameter is set. In such case, the returned type is str. By default, check_same_thread is True and only the creating thread may use the connection. If set False, the returned connection may be shared across multiple threads. When using multiple threads with the same connection writing operations should be serialized by the user to avoid data corruption. By default, the sqlite3 module uses its Connection class for the connect call. You can, however, subclass the Connection class and make connect() use your class instead by providing your class for the factory parameter. Consult the section SQLite and Python types of this manual for details. The sqlite3 module internally uses a statement cache to avoid SQL parsing overhead. If you want to explicitly set the number of statements that are cached for the connection, you can set the cached_statements parameter. The currently implemented default is to cache 100 statements. If uri is true, database is interpreted as a URI. This allows you to specify options. For example, to open a database in read-only mode you can use: db = sqlite3.connect('file:path/to/database?mode=ro', uri=True)
More information about this feature, including a list of recognized options, can be found in the SQLite URI documentation. Raises an auditing event sqlite3.connect with argument database. Changed in version 3.4: Added the uri parameter. Changed in version 3.7: database can now also be a path-like object, not only a string.
sqlite3.register_converter(typename, callable)
Registers a callable to convert a bytestring from the database into a custom Python type. The callable will be invoked for all database values that are of the type typename. Confer the parameter detect_types of the connect() function for how the type detection works. Note that typename and the name of the type in your query are matched in case-insensitive manner.
sqlite3.register_adapter(type, callable)
Registers a callable to convert the custom Python type type into one of SQLite’s supported types. The callable callable accepts as single parameter the Python value, and must return a value of the following types: int, float, str or bytes.
sqlite3.complete_statement(sql)
Returns True if the string sql contains one or more complete SQL statements terminated by semicolons. It does not verify that the SQL is syntactically correct, only that there are no unclosed string literals and the statement is terminated by a semicolon. This can be used to build a shell for SQLite, as in the following example: # A minimal SQLite shell for experiments
import sqlite3
con = sqlite3.connect(":memory:")
con.isolation_level = None
cur = con.cursor()
buffer = ""
print("Enter your SQL commands to execute in sqlite3.")
print("Enter a blank line to exit.")
while True:
line = input()
if line == "":
break
buffer += line
if sqlite3.complete_statement(buffer):
try:
buffer = buffer.strip()
cur.execute(buffer)
if buffer.lstrip().upper().startswith("SELECT"):
print(cur.fetchall())
except sqlite3.Error as e:
print("An error occurred:", e.args[0])
buffer = ""
con.close()
sqlite3.enable_callback_tracebacks(flag)
By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on sys.stderr. Use False to disable the feature again.
Connection Objects
class sqlite3.Connection
A SQLite database connection has the following attributes and methods:
isolation_level
Get or set the current default isolation level. None for autocommit mode or one of “DEFERRED”, “IMMEDIATE” or “EXCLUSIVE”. See section Controlling Transactions for a more detailed explanation.
in_transaction
True if a transaction is active (there are uncommitted changes), False otherwise. Read-only attribute. New in version 3.2.
cursor(factory=Cursor)
The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses.
commit()
This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. If you wonder why you don’t see the data you’ve written to the database, please check you didn’t forget to call this method.
rollback()
This method rolls back any changes to the database since the last call to commit().
close()
This closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost!
execute(sql[, parameters])
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s execute() method with the parameters given, and returns the cursor.
executemany(sql[, parameters])
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executemany() method with the parameters given, and returns the cursor.
executescript(sql_script)
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executescript() method with the given sql_script, and returns the cursor.
create_function(name, num_params, func, *, deterministic=False)
Creates a user-defined function that you can later use from within SQL statements under the function name name. num_params is the number of parameters the function accepts (if num_params is -1, the function may take any number of arguments), and func is a Python callable that is called as the SQL function. If deterministic is true, the created function is marked as deterministic, which allows SQLite to perform additional optimizations. This flag is supported by SQLite 3.8.3 or higher, NotSupportedError will be raised if used with older versions. The function can return any of the types supported by SQLite: bytes, str, int, float and None. Changed in version 3.8: The deterministic parameter was added. Example: import sqlite3
import hashlib
def md5sum(t):
return hashlib.md5(t).hexdigest()
con = sqlite3.connect(":memory:")
con.create_function("md5", 1, md5sum)
cur = con.cursor()
cur.execute("select md5(?)", (b"foo",))
print(cur.fetchone()[0])
con.close()
create_aggregate(name, num_params, aggregate_class)
Creates a user-defined aggregate function. The aggregate class must implement a step method, which accepts the number of parameters num_params (if num_params is -1, the function may take any number of arguments), and a finalize method which will return the final result of the aggregate. The finalize method can return any of the types supported by SQLite: bytes, str, int, float and None. Example: import sqlite3
class MySum:
def __init__(self):
self.count = 0
def step(self, value):
self.count += value
def finalize(self):
return self.count
con = sqlite3.connect(":memory:")
con.create_aggregate("mysum", 1, MySum)
cur = con.cursor()
cur.execute("create table test(i)")
cur.execute("insert into test(i) values (1)")
cur.execute("insert into test(i) values (2)")
cur.execute("select mysum(i) from test")
print(cur.fetchone()[0])
con.close()
create_collation(name, callable)
Creates a collation with the specified name and callable. The callable will be passed two string arguments. It should return -1 if the first is ordered lower than the second, 0 if they are ordered equal and 1 if the first is ordered higher than the second. Note that this controls sorting (ORDER BY in SQL) so your comparisons don’t affect other SQL operations. Note that the callable will get its parameters as Python bytestrings, which will normally be encoded in UTF-8. The following example shows a custom collation that sorts “the wrong way”: import sqlite3
def collate_reverse(string1, string2):
if string1 == string2:
return 0
elif string1 < string2:
return 1
else:
return -1
con = sqlite3.connect(":memory:")
con.create_collation("reverse", collate_reverse)
cur = con.cursor()
cur.execute("create table test(x)")
cur.executemany("insert into test(x) values (?)", [("a",), ("b",)])
cur.execute("select x from test order by x collate reverse")
for row in cur:
print(row)
con.close()
To remove a collation, call create_collation with None as callable: con.create_collation("reverse", None)
interrupt()
You can call this method from a different thread to abort any queries that might be executing on the connection. The query will then abort and the caller will get an exception.
set_authorizer(authorizer_callback)
This routine registers a callback. The callback is invoked for each attempt to access a column of a table in the database. The callback should return SQLITE_OK if access is allowed, SQLITE_DENY if the entire SQL statement should be aborted with an error and SQLITE_IGNORE if the column should be treated as a NULL value. These constants are available in the sqlite3 module. The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code. Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.
set_progress_handler(handler, n)
This routine registers a callback. The callback is invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI. If you want to clear any previously installed progress handler, call the method with None for handler. Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception.
set_trace_callback(trace_callback)
Registers trace_callback to be called for each SQL statement that is actually executed by the SQLite backend. The only argument passed to the callback is the statement (as string) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the Python module and the execution of triggers defined in the current database. Passing None as trace_callback will disable the trace callback. New in version 3.3.
enable_load_extension(enabled)
This routine allows/disallows the SQLite engine to load SQLite extensions from shared libraries. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite. Loadable extensions are disabled by default. See 1. New in version 3.2. import sqlite3
con = sqlite3.connect(":memory:")
# enable extension loading
con.enable_load_extension(True)
# Load the fulltext search extension
con.execute("select load_extension('./fts3.so')")
# alternatively you can load the extension using an API call:
# con.load_extension("./fts3.so")
# disable extension loading again
con.enable_load_extension(False)
# example from SQLite wiki
con.execute("create virtual table recipe using fts3(name, ingredients)")
con.executescript("""
insert into recipe (name, ingredients) values ('broccoli stew', 'broccoli peppers cheese tomatoes');
insert into recipe (name, ingredients) values ('pumpkin stew', 'pumpkin onions garlic celery');
insert into recipe (name, ingredients) values ('broccoli pie', 'broccoli cheese onions flour');
insert into recipe (name, ingredients) values ('pumpkin pie', 'pumpkin sugar flour butter');
""")
for row in con.execute("select rowid, name, ingredients from recipe where name match 'pie'"):
print(row)
con.close()
load_extension(path)
This routine loads a SQLite extension from a shared library. You have to enable extension loading with enable_load_extension() before you can use this routine. Loadable extensions are disabled by default. See 1. New in version 3.2.
row_factory
You can change this attribute to a callable that accepts the cursor and the original row as a tuple and will return the real result row. This way, you can implement more advanced ways of returning results, such as returning an object that can also access columns by name. Example: import sqlite3
def dict_factory(cursor, row):
d = {}
for idx, col in enumerate(cursor.description):
d[col[0]] = row[idx]
return d
con = sqlite3.connect(":memory:")
con.row_factory = dict_factory
cur = con.cursor()
cur.execute("select 1 as a")
print(cur.fetchone()["a"])
con.close()
If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting row_factory to the highly-optimized sqlite3.Row type. Row provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution.
text_factory
Using this attribute you can control what objects are returned for the TEXT data type. By default, this attribute is set to str and the sqlite3 module will return Unicode objects for TEXT. If you want to return bytestrings instead, you can set it to bytes. You can also set it to any other callable that accepts a single bytestring parameter and returns the resulting object. See the following example code for illustration: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
AUSTRIA = "\xd6sterreich"
# by default, rows are returned as Unicode
cur.execute("select ?", (AUSTRIA,))
row = cur.fetchone()
assert row[0] == AUSTRIA
# but we can make sqlite3 always return bytestrings ...
con.text_factory = bytes
cur.execute("select ?", (AUSTRIA,))
row = cur.fetchone()
assert type(row[0]) is bytes
# the bytestrings will be encoded in UTF-8, unless you stored garbage in the
# database ...
assert row[0] == AUSTRIA.encode("utf-8")
# we can also implement a custom text_factory ...
# here we implement one that appends "foo" to all strings
con.text_factory = lambda x: x.decode("utf-8") + "foo"
cur.execute("select ?", ("bar",))
row = cur.fetchone()
assert row[0] == "barfoo"
con.close()
total_changes
Returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.
iterdump()
Returns an iterator to dump the database in an SQL text format. Useful when saving an in-memory database for later restoration. This function provides the same capabilities as the .dump command in the sqlite3 shell. Example: # Convert file existing_db.db to SQL dump file dump.sql
import sqlite3
con = sqlite3.connect('existing_db.db')
with open('dump.sql', 'w') as f:
for line in con.iterdump():
f.write('%s\n' % line)
con.close()
backup(target, *, pages=-1, progress=None, name="main", sleep=0.250)
This method makes a backup of a SQLite database even while it’s being accessed by other clients, or concurrently by the same connection. The copy will be written into the mandatory argument target, that must be another Connection instance. By default, or when pages is either 0 or a negative integer, the entire database is copied in a single step; otherwise the method performs a loop copying up to pages pages at a time. If progress is specified, it must either be None or a callable object that will be executed at each iteration with three integer arguments, respectively the status of the last iteration, the remaining number of pages still to be copied and the total number of pages. The name argument specifies the database name that will be copied: it must be a string containing either "main", the default, to indicate the main database, "temp" to indicate the temporary database or the name specified after the AS keyword in an ATTACH DATABASE statement for an attached database. The sleep argument specifies the number of seconds to sleep by between successive attempts to backup remaining pages, can be specified either as an integer or a floating point value. Example 1, copy an existing database into another: import sqlite3
def progress(status, remaining, total):
print(f'Copied {total-remaining} of {total} pages...')
con = sqlite3.connect('existing_db.db')
bck = sqlite3.connect('backup.db')
with bck:
con.backup(bck, pages=1, progress=progress)
bck.close()
con.close()
Example 2, copy an existing database into a transient copy: import sqlite3
source = sqlite3.connect('existing_db.db')
dest = sqlite3.connect(':memory:')
source.backup(dest)
Availability: SQLite 3.6.11 or higher New in version 3.7.
Cursor Objects
class sqlite3.Cursor
A Cursor instance has the following attributes and methods.
execute(sql[, parameters])
Executes an SQL statement. Values may be bound to the statement using placeholders. execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call.
executemany(sql, seq_of_parameters)
Executes a parameterized SQL command against all parameter sequences or mappings found in the sequence seq_of_parameters. The sqlite3 module also allows using an iterator yielding parameters instead of a sequence. import sqlite3
class IterChars:
def __init__(self):
self.count = ord('a')
def __iter__(self):
return self
def __next__(self):
if self.count > ord('z'):
raise StopIteration
self.count += 1
return (chr(self.count - 1),) # this is a 1-tuple
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table characters(c)")
theIter = IterChars()
cur.executemany("insert into characters(c) values (?)", theIter)
cur.execute("select c from characters")
print(cur.fetchall())
con.close()
Here’s a shorter example using a generator: import sqlite3
import string
def char_generator():
for c in string.ascii_lowercase:
yield (c,)
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table characters(c)")
cur.executemany("insert into characters(c) values (?)", char_generator())
cur.execute("select c from characters")
print(cur.fetchall())
con.close()
executescript(sql_script)
This is a nonstandard convenience method for executing multiple SQL statements at once. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter. sql_script can be an instance of str. Example: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.executescript("""
create table person(
firstname,
lastname,
age
);
create table book(
title,
author,
published
);
insert into book(title, author, published)
values (
'Dirk Gently''s Holistic Detective Agency',
'Douglas Adams',
1987
);
""")
con.close()
fetchone()
Fetches the next row of a query result set, returning a single sequence, or None when no more data is available.
fetchmany(size=cursor.arraysize)
Fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available. The number of rows to fetch per call is specified by the size parameter. If it is not given, the cursor’s arraysize determines the number of rows to be fetched. The method should try to fetch as many rows as indicated by the size parameter. If this is not possible due to the specified number of rows not being available, fewer rows may be returned. Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next.
fetchall()
Fetches all (remaining) rows of a query result, returning a list. Note that the cursor’s arraysize attribute can affect the performance of this operation. An empty list is returned when no rows are available.
close()
Close the cursor now (rather than whenever __del__ is called). The cursor will be unusable from this point forward; a ProgrammingError exception will be raised if any operation is attempted with the cursor.
rowcount
Although the Cursor class of the sqlite3 module implements this attribute, the database engine’s own support for the determination of “rows affected”/”rows selected” is quirky. For executemany() statements, the number of modifications are summed up into rowcount. As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”. This includes SELECT statements because we cannot determine the number of rows a query produced until all rows were fetched. With SQLite versions before 3.6.5, rowcount is set to 0 if you make a DELETE FROM table without any condition.
lastrowid
This read-only attribute provides the rowid of the last modified row. It is only set if you issued an INSERT or a REPLACE statement using the execute() method. For operations other than INSERT or REPLACE or when executemany() is called, lastrowid is set to None. If the INSERT or REPLACE statement failed to insert the previous successful rowid is returned. Changed in version 3.6: Added support for the REPLACE statement.
arraysize
Read/write attribute that controls the number of rows returned by fetchmany(). The default value is 1 which means a single row would be fetched per call.
description
This read-only attribute provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None. It is set for SELECT statements without any matching rows as well.
connection
This read-only attribute provides the SQLite database Connection used by the Cursor object. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con: >>> con = sqlite3.connect(":memory:")
>>> cur = con.cursor()
>>> cur.connection == con
True
Row Objects
class sqlite3.Row
A Row instance serves as a highly optimized row_factory for Connection objects. It tries to mimic a tuple in most of its features. It supports mapping access by column name and index, iteration, representation, equality testing and len(). If two Row objects have exactly the same columns and their members are equal, they compare equal.
keys()
This method returns a list of column names. Immediately after a query, it is the first member of each tuple in Cursor.description.
Changed in version 3.5: Added support of slicing.
Let’s assume we initialize a table as in the example given above: con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute('''create table stocks
(date text, trans text, symbol text,
qty real, price real)''')
cur.execute("""insert into stocks
values ('2006-01-05','BUY','RHAT',100,35.14)""")
con.commit()
cur.close()
Now we plug Row in: >>> con.row_factory = sqlite3.Row
>>> cur = con.cursor()
>>> cur.execute('select * from stocks')
<sqlite3.Cursor object at 0x7f4e7dd8fa80>
>>> r = cur.fetchone()
>>> type(r)
<class 'sqlite3.Row'>
>>> tuple(r)
('2006-01-05', 'BUY', 'RHAT', 100.0, 35.14)
>>> len(r)
5
>>> r[2]
'RHAT'
>>> r.keys()
['date', 'trans', 'symbol', 'qty', 'price']
>>> r['qty']
100.0
>>> for member in r:
... print(member)
...
2006-01-05
BUY
RHAT
100.0
35.14
Exceptions
exception sqlite3.Warning
A subclass of Exception.
exception sqlite3.Error
The base class of the other exceptions in this module. It is a subclass of Exception.
exception sqlite3.DatabaseError
Exception raised for errors that are related to the database.
exception sqlite3.IntegrityError
Exception raised when the relational integrity of the database is affected, e.g. a foreign key check fails. It is a subclass of DatabaseError.
exception sqlite3.ProgrammingError
Exception raised for programming errors, e.g. table not found or already exists, syntax error in the SQL statement, wrong number of parameters specified, etc. It is a subclass of DatabaseError.
exception sqlite3.OperationalError
Exception raised for errors that are related to the database’s operation and not necessarily under the control of the programmer, e.g. an unexpected disconnect occurs, the data source name is not found, a transaction could not be processed, etc. It is a subclass of DatabaseError.
exception sqlite3.NotSupportedError
Exception raised in case a method or database API was used which is not supported by the database, e.g. calling the rollback() method on a connection that does not support transaction or has transactions turned off. It is a subclass of DatabaseError.
SQLite and Python types Introduction SQLite natively supports the following types: NULL, INTEGER, REAL, TEXT, BLOB. The following Python types can thus be sent to SQLite without any problem:
Python type SQLite type
None NULL
int INTEGER
float REAL
str TEXT
bytes BLOB This is how SQLite types are converted to Python types by default:
SQLite type Python type
NULL None
INTEGER int
REAL float
TEXT depends on text_factory, str by default
BLOB bytes The type system of the sqlite3 module is extensible in two ways: you can store additional Python types in a SQLite database via object adaptation, and you can let the sqlite3 module convert SQLite types to different Python types via converters. Using adapters to store additional Python types in SQLite databases As described before, SQLite supports only a limited set of types natively. To use other Python types with SQLite, you must adapt them to one of the sqlite3 module’s supported types for SQLite: one of NoneType, int, float, str, bytes. There are two ways to enable the sqlite3 module to adapt a custom Python type to one of the supported ones. Letting your object adapt itself This is a good approach if you write the class yourself. Let’s suppose you have a class like this: class Point:
def __init__(self, x, y):
self.x, self.y = x, y
Now you want to store the point in a single SQLite column. First you’ll have to choose one of the supported types to be used for representing the point. Let’s just use str and separate the coordinates using a semicolon. Then you need to give your class a method __conform__(self, protocol) which must return the converted value. The parameter protocol will be PrepareProtocol. import sqlite3
class Point:
def __init__(self, x, y):
self.x, self.y = x, y
def __conform__(self, protocol):
if protocol is sqlite3.PrepareProtocol:
return "%f;%f" % (self.x, self.y)
con = sqlite3.connect(":memory:")
cur = con.cursor()
p = Point(4.0, -3.2)
cur.execute("select ?", (p,))
print(cur.fetchone()[0])
con.close()
Registering an adapter callable The other possibility is to create a function that converts the type to the string representation and register the function with register_adapter(). import sqlite3
class Point:
def __init__(self, x, y):
self.x, self.y = x, y
def adapt_point(point):
return "%f;%f" % (point.x, point.y)
sqlite3.register_adapter(Point, adapt_point)
con = sqlite3.connect(":memory:")
cur = con.cursor()
p = Point(4.0, -3.2)
cur.execute("select ?", (p,))
print(cur.fetchone()[0])
con.close()
The sqlite3 module has two default adapters for Python’s built-in datetime.date and datetime.datetime types. Now let’s suppose we want to store datetime.datetime objects not in ISO representation, but as a Unix timestamp. import sqlite3
import datetime
import time
def adapt_datetime(ts):
return time.mktime(ts.timetuple())
sqlite3.register_adapter(datetime.datetime, adapt_datetime)
con = sqlite3.connect(":memory:")
cur = con.cursor()
now = datetime.datetime.now()
cur.execute("select ?", (now,))
print(cur.fetchone()[0])
con.close()
Converting SQLite values to custom Python types Writing an adapter lets you send custom Python types to SQLite. But to make it really useful we need to make the Python to SQLite to Python roundtrip work. Enter converters. Let’s go back to the Point class. We stored the x and y coordinates separated via semicolons as strings in SQLite. First, we’ll define a converter function that accepts the string as a parameter and constructs a Point object from it. Note Converter functions always get called with a bytes object, no matter under which data type you sent the value to SQLite. def convert_point(s):
x, y = map(float, s.split(b";"))
return Point(x, y)
Now you need to make the sqlite3 module know that what you select from the database is actually a point. There are two ways of doing this: Implicitly via the declared type Explicitly via the column name Both ways are described in section Module functions and constants, in the entries for the constants PARSE_DECLTYPES and PARSE_COLNAMES. The following example illustrates both approaches. import sqlite3
class Point:
def __init__(self, x, y):
self.x, self.y = x, y
def __repr__(self):
return "(%f;%f)" % (self.x, self.y)
def adapt_point(point):
return ("%f;%f" % (point.x, point.y)).encode('ascii')
def convert_point(s):
x, y = list(map(float, s.split(b";")))
return Point(x, y)
# Register the adapter
sqlite3.register_adapter(Point, adapt_point)
# Register the converter
sqlite3.register_converter("point", convert_point)
p = Point(4.0, -3.2)
#########################
# 1) Using declared types
con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES)
cur = con.cursor()
cur.execute("create table test(p point)")
cur.execute("insert into test(p) values (?)", (p,))
cur.execute("select p from test")
print("with declared types:", cur.fetchone()[0])
cur.close()
con.close()
#######################
# 1) Using column names
con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_COLNAMES)
cur = con.cursor()
cur.execute("create table test(p)")
cur.execute("insert into test(p) values (?)", (p,))
cur.execute('select p as "p [point]" from test')
print("with column names:", cur.fetchone()[0])
cur.close()
con.close()
Default adapters and converters There are default adapters for the date and datetime types in the datetime module. They will be sent as ISO dates/ISO timestamps to SQLite. The default converters are registered under the name “date” for datetime.date and under the name “timestamp” for datetime.datetime. This way, you can use date/timestamps from Python without any additional fiddling in most cases. The format of the adapters is also compatible with the experimental SQLite date/time functions. The following example demonstrates this. import sqlite3
import datetime
con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
cur = con.cursor()
cur.execute("create table test(d date, ts timestamp)")
today = datetime.date.today()
now = datetime.datetime.now()
cur.execute("insert into test(d, ts) values (?, ?)", (today, now))
cur.execute("select d, ts from test")
row = cur.fetchone()
print(today, "=>", row[0], type(row[0]))
print(now, "=>", row[1], type(row[1]))
cur.execute('select current_date as "d [date]", current_timestamp as "ts [timestamp]"')
row = cur.fetchone()
print("current_date", row[0], type(row[0]))
print("current_timestamp", row[1], type(row[1]))
con.close()
If a timestamp stored in SQLite has a fractional part longer than 6 numbers, its value will be truncated to microsecond precision by the timestamp converter. Controlling Transactions The underlying sqlite3 library operates in autocommit mode by default, but the Python sqlite3 module by default does not. autocommit mode means that statements that modify the database take effect immediately. A BEGIN or SAVEPOINT statement disables autocommit mode, and a COMMIT, a ROLLBACK, or a RELEASE that ends the outermost transaction, turns autocommit mode back on. The Python sqlite3 module by default issues a BEGIN statement implicitly before a Data Modification Language (DML) statement (i.e. INSERT/UPDATE/DELETE/REPLACE). You can control which kind of BEGIN statements sqlite3 implicitly executes via the isolation_level parameter to the connect() call, or via the isolation_level property of connections. If you specify no isolation_level, a plain BEGIN is used, which is equivalent to specifying DEFERRED. Other possible values are IMMEDIATE and EXCLUSIVE. You can disable the sqlite3 module’s implicit transaction management by setting isolation_level to None. This will leave the underlying sqlite3 library operating in autocommit mode. You can then completely control the transaction state by explicitly issuing BEGIN, ROLLBACK, SAVEPOINT, and RELEASE statements in your code. Changed in version 3.6: sqlite3 used to implicitly commit an open transaction before DDL statements. This is no longer the case. Using sqlite3 efficiently Using shortcut methods Using the nonstandard execute(), executemany() and executescript() methods of the Connection object, your code can be written more concisely because you don’t have to create the (often superfluous) Cursor objects explicitly. Instead, the Cursor objects are created implicitly and these shortcut methods return the cursor objects. This way, you can execute a SELECT statement and iterate over it directly using only a single call on the Connection object. import sqlite3
persons = [
("Hugo", "Boss"),
("Calvin", "Klein")
]
con = sqlite3.connect(":memory:")
# Create the table
con.execute("create table person(firstname, lastname)")
# Fill the table
con.executemany("insert into person(firstname, lastname) values (?, ?)", persons)
# Print the table contents
for row in con.execute("select firstname, lastname from person"):
print(row)
print("I just deleted", con.execute("delete from person").rowcount, "rows")
# close is not a shortcut method and it's not called automatically,
# so the connection object should be closed manually
con.close()
Accessing columns by name instead of by index One useful feature of the sqlite3 module is the built-in sqlite3.Row class designed to be used as a row factory. Rows wrapped with this class can be accessed both by index (like tuples) and case-insensitively by name: import sqlite3
con = sqlite3.connect(":memory:")
con.row_factory = sqlite3.Row
cur = con.cursor()
cur.execute("select 'John' as name, 42 as age")
for row in cur:
assert row[0] == row["name"]
assert row["name"] == row["nAmE"]
assert row[1] == row["age"]
assert row[1] == row["AgE"]
con.close()
Using the connection as a context manager Connection objects can be used as context managers that automatically commit or rollback transactions. In the event of an exception, the transaction is rolled back; otherwise, the transaction is committed: import sqlite3
con = sqlite3.connect(":memory:")
con.execute("create table person (id integer primary key, firstname varchar unique)")
# Successful, con.commit() is called automatically afterwards
with con:
con.execute("insert into person(firstname) values (?)", ("Joe",))
# con.rollback() is called after the with block finishes with an exception, the
# exception is still raised and must be caught
try:
with con:
con.execute("insert into person(firstname) values (?)", ("Joe",))
except sqlite3.IntegrityError:
print("couldn't add Joe twice")
# Connection object used as context manager only commits or rollbacks transactions,
# so the connection object should be closed manually
con.close()
Footnotes
1(1,2)
The sqlite3 module is not built with loadable extension support by default, because some platforms (notably Mac OS X) have SQLite libraries which are compiled without this feature. To get loadable extension support, you must pass --enable-loadable-sqlite-extensions to configure. | python.library.sqlite3 |
sqlite3.complete_statement(sql)
Returns True if the string sql contains one or more complete SQL statements terminated by semicolons. It does not verify that the SQL is syntactically correct, only that there are no unclosed string literals and the statement is terminated by a semicolon. This can be used to build a shell for SQLite, as in the following example: # A minimal SQLite shell for experiments
import sqlite3
con = sqlite3.connect(":memory:")
con.isolation_level = None
cur = con.cursor()
buffer = ""
print("Enter your SQL commands to execute in sqlite3.")
print("Enter a blank line to exit.")
while True:
line = input()
if line == "":
break
buffer += line
if sqlite3.complete_statement(buffer):
try:
buffer = buffer.strip()
cur.execute(buffer)
if buffer.lstrip().upper().startswith("SELECT"):
print(cur.fetchall())
except sqlite3.Error as e:
print("An error occurred:", e.args[0])
buffer = ""
con.close() | python.library.sqlite3#sqlite3.complete_statement |
sqlite3.connect(database[, timeout, detect_types, isolation_level, check_same_thread, factory, cached_statements, uri])
Opens a connection to the SQLite database file database. By default returns a Connection object, unless a custom factory is given. database is a path-like object giving the pathname (absolute or relative to the current working directory) of the database file to be opened. You can use ":memory:" to open a database connection to a database that resides in RAM instead of on disk. When a database is accessed by multiple connections, and one of the processes modifies the database, the SQLite database is locked until that transaction is committed. The timeout parameter specifies how long the connection should wait for the lock to go away until raising an exception. The default for the timeout parameter is 5.0 (five seconds). For the isolation_level parameter, please see the isolation_level property of Connection objects. SQLite natively supports only the types TEXT, INTEGER, REAL, BLOB and NULL. If you want to use other types you must add support for them yourself. The detect_types parameter and the using custom converters registered with the module-level register_converter() function allow you to easily do that. detect_types defaults to 0 (i. e. off, no type detection), you can set it to any combination of PARSE_DECLTYPES and PARSE_COLNAMES to turn type detection on. Due to SQLite behaviour, types can’t be detected for generated fields (for example max(data)), even when detect_types parameter is set. In such case, the returned type is str. By default, check_same_thread is True and only the creating thread may use the connection. If set False, the returned connection may be shared across multiple threads. When using multiple threads with the same connection writing operations should be serialized by the user to avoid data corruption. By default, the sqlite3 module uses its Connection class for the connect call. You can, however, subclass the Connection class and make connect() use your class instead by providing your class for the factory parameter. Consult the section SQLite and Python types of this manual for details. The sqlite3 module internally uses a statement cache to avoid SQL parsing overhead. If you want to explicitly set the number of statements that are cached for the connection, you can set the cached_statements parameter. The currently implemented default is to cache 100 statements. If uri is true, database is interpreted as a URI. This allows you to specify options. For example, to open a database in read-only mode you can use: db = sqlite3.connect('file:path/to/database?mode=ro', uri=True)
More information about this feature, including a list of recognized options, can be found in the SQLite URI documentation. Raises an auditing event sqlite3.connect with argument database. Changed in version 3.4: Added the uri parameter. Changed in version 3.7: database can now also be a path-like object, not only a string. | python.library.sqlite3#sqlite3.connect |
class sqlite3.Connection
A SQLite database connection has the following attributes and methods:
isolation_level
Get or set the current default isolation level. None for autocommit mode or one of “DEFERRED”, “IMMEDIATE” or “EXCLUSIVE”. See section Controlling Transactions for a more detailed explanation.
in_transaction
True if a transaction is active (there are uncommitted changes), False otherwise. Read-only attribute. New in version 3.2.
cursor(factory=Cursor)
The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses.
commit()
This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. If you wonder why you don’t see the data you’ve written to the database, please check you didn’t forget to call this method.
rollback()
This method rolls back any changes to the database since the last call to commit().
close()
This closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost!
execute(sql[, parameters])
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s execute() method with the parameters given, and returns the cursor.
executemany(sql[, parameters])
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executemany() method with the parameters given, and returns the cursor.
executescript(sql_script)
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executescript() method with the given sql_script, and returns the cursor.
create_function(name, num_params, func, *, deterministic=False)
Creates a user-defined function that you can later use from within SQL statements under the function name name. num_params is the number of parameters the function accepts (if num_params is -1, the function may take any number of arguments), and func is a Python callable that is called as the SQL function. If deterministic is true, the created function is marked as deterministic, which allows SQLite to perform additional optimizations. This flag is supported by SQLite 3.8.3 or higher, NotSupportedError will be raised if used with older versions. The function can return any of the types supported by SQLite: bytes, str, int, float and None. Changed in version 3.8: The deterministic parameter was added. Example: import sqlite3
import hashlib
def md5sum(t):
return hashlib.md5(t).hexdigest()
con = sqlite3.connect(":memory:")
con.create_function("md5", 1, md5sum)
cur = con.cursor()
cur.execute("select md5(?)", (b"foo",))
print(cur.fetchone()[0])
con.close()
create_aggregate(name, num_params, aggregate_class)
Creates a user-defined aggregate function. The aggregate class must implement a step method, which accepts the number of parameters num_params (if num_params is -1, the function may take any number of arguments), and a finalize method which will return the final result of the aggregate. The finalize method can return any of the types supported by SQLite: bytes, str, int, float and None. Example: import sqlite3
class MySum:
def __init__(self):
self.count = 0
def step(self, value):
self.count += value
def finalize(self):
return self.count
con = sqlite3.connect(":memory:")
con.create_aggregate("mysum", 1, MySum)
cur = con.cursor()
cur.execute("create table test(i)")
cur.execute("insert into test(i) values (1)")
cur.execute("insert into test(i) values (2)")
cur.execute("select mysum(i) from test")
print(cur.fetchone()[0])
con.close()
create_collation(name, callable)
Creates a collation with the specified name and callable. The callable will be passed two string arguments. It should return -1 if the first is ordered lower than the second, 0 if they are ordered equal and 1 if the first is ordered higher than the second. Note that this controls sorting (ORDER BY in SQL) so your comparisons don’t affect other SQL operations. Note that the callable will get its parameters as Python bytestrings, which will normally be encoded in UTF-8. The following example shows a custom collation that sorts “the wrong way”: import sqlite3
def collate_reverse(string1, string2):
if string1 == string2:
return 0
elif string1 < string2:
return 1
else:
return -1
con = sqlite3.connect(":memory:")
con.create_collation("reverse", collate_reverse)
cur = con.cursor()
cur.execute("create table test(x)")
cur.executemany("insert into test(x) values (?)", [("a",), ("b",)])
cur.execute("select x from test order by x collate reverse")
for row in cur:
print(row)
con.close()
To remove a collation, call create_collation with None as callable: con.create_collation("reverse", None)
interrupt()
You can call this method from a different thread to abort any queries that might be executing on the connection. The query will then abort and the caller will get an exception.
set_authorizer(authorizer_callback)
This routine registers a callback. The callback is invoked for each attempt to access a column of a table in the database. The callback should return SQLITE_OK if access is allowed, SQLITE_DENY if the entire SQL statement should be aborted with an error and SQLITE_IGNORE if the column should be treated as a NULL value. These constants are available in the sqlite3 module. The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code. Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.
set_progress_handler(handler, n)
This routine registers a callback. The callback is invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI. If you want to clear any previously installed progress handler, call the method with None for handler. Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception.
set_trace_callback(trace_callback)
Registers trace_callback to be called for each SQL statement that is actually executed by the SQLite backend. The only argument passed to the callback is the statement (as string) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the Python module and the execution of triggers defined in the current database. Passing None as trace_callback will disable the trace callback. New in version 3.3.
enable_load_extension(enabled)
This routine allows/disallows the SQLite engine to load SQLite extensions from shared libraries. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite. Loadable extensions are disabled by default. See 1. New in version 3.2. import sqlite3
con = sqlite3.connect(":memory:")
# enable extension loading
con.enable_load_extension(True)
# Load the fulltext search extension
con.execute("select load_extension('./fts3.so')")
# alternatively you can load the extension using an API call:
# con.load_extension("./fts3.so")
# disable extension loading again
con.enable_load_extension(False)
# example from SQLite wiki
con.execute("create virtual table recipe using fts3(name, ingredients)")
con.executescript("""
insert into recipe (name, ingredients) values ('broccoli stew', 'broccoli peppers cheese tomatoes');
insert into recipe (name, ingredients) values ('pumpkin stew', 'pumpkin onions garlic celery');
insert into recipe (name, ingredients) values ('broccoli pie', 'broccoli cheese onions flour');
insert into recipe (name, ingredients) values ('pumpkin pie', 'pumpkin sugar flour butter');
""")
for row in con.execute("select rowid, name, ingredients from recipe where name match 'pie'"):
print(row)
con.close()
load_extension(path)
This routine loads a SQLite extension from a shared library. You have to enable extension loading with enable_load_extension() before you can use this routine. Loadable extensions are disabled by default. See 1. New in version 3.2.
row_factory
You can change this attribute to a callable that accepts the cursor and the original row as a tuple and will return the real result row. This way, you can implement more advanced ways of returning results, such as returning an object that can also access columns by name. Example: import sqlite3
def dict_factory(cursor, row):
d = {}
for idx, col in enumerate(cursor.description):
d[col[0]] = row[idx]
return d
con = sqlite3.connect(":memory:")
con.row_factory = dict_factory
cur = con.cursor()
cur.execute("select 1 as a")
print(cur.fetchone()["a"])
con.close()
If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting row_factory to the highly-optimized sqlite3.Row type. Row provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution.
text_factory
Using this attribute you can control what objects are returned for the TEXT data type. By default, this attribute is set to str and the sqlite3 module will return Unicode objects for TEXT. If you want to return bytestrings instead, you can set it to bytes. You can also set it to any other callable that accepts a single bytestring parameter and returns the resulting object. See the following example code for illustration: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
AUSTRIA = "\xd6sterreich"
# by default, rows are returned as Unicode
cur.execute("select ?", (AUSTRIA,))
row = cur.fetchone()
assert row[0] == AUSTRIA
# but we can make sqlite3 always return bytestrings ...
con.text_factory = bytes
cur.execute("select ?", (AUSTRIA,))
row = cur.fetchone()
assert type(row[0]) is bytes
# the bytestrings will be encoded in UTF-8, unless you stored garbage in the
# database ...
assert row[0] == AUSTRIA.encode("utf-8")
# we can also implement a custom text_factory ...
# here we implement one that appends "foo" to all strings
con.text_factory = lambda x: x.decode("utf-8") + "foo"
cur.execute("select ?", ("bar",))
row = cur.fetchone()
assert row[0] == "barfoo"
con.close()
total_changes
Returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.
iterdump()
Returns an iterator to dump the database in an SQL text format. Useful when saving an in-memory database for later restoration. This function provides the same capabilities as the .dump command in the sqlite3 shell. Example: # Convert file existing_db.db to SQL dump file dump.sql
import sqlite3
con = sqlite3.connect('existing_db.db')
with open('dump.sql', 'w') as f:
for line in con.iterdump():
f.write('%s\n' % line)
con.close()
backup(target, *, pages=-1, progress=None, name="main", sleep=0.250)
This method makes a backup of a SQLite database even while it’s being accessed by other clients, or concurrently by the same connection. The copy will be written into the mandatory argument target, that must be another Connection instance. By default, or when pages is either 0 or a negative integer, the entire database is copied in a single step; otherwise the method performs a loop copying up to pages pages at a time. If progress is specified, it must either be None or a callable object that will be executed at each iteration with three integer arguments, respectively the status of the last iteration, the remaining number of pages still to be copied and the total number of pages. The name argument specifies the database name that will be copied: it must be a string containing either "main", the default, to indicate the main database, "temp" to indicate the temporary database or the name specified after the AS keyword in an ATTACH DATABASE statement for an attached database. The sleep argument specifies the number of seconds to sleep by between successive attempts to backup remaining pages, can be specified either as an integer or a floating point value. Example 1, copy an existing database into another: import sqlite3
def progress(status, remaining, total):
print(f'Copied {total-remaining} of {total} pages...')
con = sqlite3.connect('existing_db.db')
bck = sqlite3.connect('backup.db')
with bck:
con.backup(bck, pages=1, progress=progress)
bck.close()
con.close()
Example 2, copy an existing database into a transient copy: import sqlite3
source = sqlite3.connect('existing_db.db')
dest = sqlite3.connect(':memory:')
source.backup(dest)
Availability: SQLite 3.6.11 or higher New in version 3.7. | python.library.sqlite3#sqlite3.Connection |
backup(target, *, pages=-1, progress=None, name="main", sleep=0.250)
This method makes a backup of a SQLite database even while it’s being accessed by other clients, or concurrently by the same connection. The copy will be written into the mandatory argument target, that must be another Connection instance. By default, or when pages is either 0 or a negative integer, the entire database is copied in a single step; otherwise the method performs a loop copying up to pages pages at a time. If progress is specified, it must either be None or a callable object that will be executed at each iteration with three integer arguments, respectively the status of the last iteration, the remaining number of pages still to be copied and the total number of pages. The name argument specifies the database name that will be copied: it must be a string containing either "main", the default, to indicate the main database, "temp" to indicate the temporary database or the name specified after the AS keyword in an ATTACH DATABASE statement for an attached database. The sleep argument specifies the number of seconds to sleep by between successive attempts to backup remaining pages, can be specified either as an integer or a floating point value. Example 1, copy an existing database into another: import sqlite3
def progress(status, remaining, total):
print(f'Copied {total-remaining} of {total} pages...')
con = sqlite3.connect('existing_db.db')
bck = sqlite3.connect('backup.db')
with bck:
con.backup(bck, pages=1, progress=progress)
bck.close()
con.close()
Example 2, copy an existing database into a transient copy: import sqlite3
source = sqlite3.connect('existing_db.db')
dest = sqlite3.connect(':memory:')
source.backup(dest)
Availability: SQLite 3.6.11 or higher New in version 3.7. | python.library.sqlite3#sqlite3.Connection.backup |
close()
This closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost! | python.library.sqlite3#sqlite3.Connection.close |
commit()
This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. If you wonder why you don’t see the data you’ve written to the database, please check you didn’t forget to call this method. | python.library.sqlite3#sqlite3.Connection.commit |
create_aggregate(name, num_params, aggregate_class)
Creates a user-defined aggregate function. The aggregate class must implement a step method, which accepts the number of parameters num_params (if num_params is -1, the function may take any number of arguments), and a finalize method which will return the final result of the aggregate. The finalize method can return any of the types supported by SQLite: bytes, str, int, float and None. Example: import sqlite3
class MySum:
def __init__(self):
self.count = 0
def step(self, value):
self.count += value
def finalize(self):
return self.count
con = sqlite3.connect(":memory:")
con.create_aggregate("mysum", 1, MySum)
cur = con.cursor()
cur.execute("create table test(i)")
cur.execute("insert into test(i) values (1)")
cur.execute("insert into test(i) values (2)")
cur.execute("select mysum(i) from test")
print(cur.fetchone()[0])
con.close() | python.library.sqlite3#sqlite3.Connection.create_aggregate |
create_collation(name, callable)
Creates a collation with the specified name and callable. The callable will be passed two string arguments. It should return -1 if the first is ordered lower than the second, 0 if they are ordered equal and 1 if the first is ordered higher than the second. Note that this controls sorting (ORDER BY in SQL) so your comparisons don’t affect other SQL operations. Note that the callable will get its parameters as Python bytestrings, which will normally be encoded in UTF-8. The following example shows a custom collation that sorts “the wrong way”: import sqlite3
def collate_reverse(string1, string2):
if string1 == string2:
return 0
elif string1 < string2:
return 1
else:
return -1
con = sqlite3.connect(":memory:")
con.create_collation("reverse", collate_reverse)
cur = con.cursor()
cur.execute("create table test(x)")
cur.executemany("insert into test(x) values (?)", [("a",), ("b",)])
cur.execute("select x from test order by x collate reverse")
for row in cur:
print(row)
con.close()
To remove a collation, call create_collation with None as callable: con.create_collation("reverse", None) | python.library.sqlite3#sqlite3.Connection.create_collation |
create_function(name, num_params, func, *, deterministic=False)
Creates a user-defined function that you can later use from within SQL statements under the function name name. num_params is the number of parameters the function accepts (if num_params is -1, the function may take any number of arguments), and func is a Python callable that is called as the SQL function. If deterministic is true, the created function is marked as deterministic, which allows SQLite to perform additional optimizations. This flag is supported by SQLite 3.8.3 or higher, NotSupportedError will be raised if used with older versions. The function can return any of the types supported by SQLite: bytes, str, int, float and None. Changed in version 3.8: The deterministic parameter was added. Example: import sqlite3
import hashlib
def md5sum(t):
return hashlib.md5(t).hexdigest()
con = sqlite3.connect(":memory:")
con.create_function("md5", 1, md5sum)
cur = con.cursor()
cur.execute("select md5(?)", (b"foo",))
print(cur.fetchone()[0])
con.close() | python.library.sqlite3#sqlite3.Connection.create_function |
cursor(factory=Cursor)
The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses. | python.library.sqlite3#sqlite3.Connection.cursor |
enable_load_extension(enabled)
This routine allows/disallows the SQLite engine to load SQLite extensions from shared libraries. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite. Loadable extensions are disabled by default. See 1. New in version 3.2. import sqlite3
con = sqlite3.connect(":memory:")
# enable extension loading
con.enable_load_extension(True)
# Load the fulltext search extension
con.execute("select load_extension('./fts3.so')")
# alternatively you can load the extension using an API call:
# con.load_extension("./fts3.so")
# disable extension loading again
con.enable_load_extension(False)
# example from SQLite wiki
con.execute("create virtual table recipe using fts3(name, ingredients)")
con.executescript("""
insert into recipe (name, ingredients) values ('broccoli stew', 'broccoli peppers cheese tomatoes');
insert into recipe (name, ingredients) values ('pumpkin stew', 'pumpkin onions garlic celery');
insert into recipe (name, ingredients) values ('broccoli pie', 'broccoli cheese onions flour');
insert into recipe (name, ingredients) values ('pumpkin pie', 'pumpkin sugar flour butter');
""")
for row in con.execute("select rowid, name, ingredients from recipe where name match 'pie'"):
print(row)
con.close() | python.library.sqlite3#sqlite3.Connection.enable_load_extension |
execute(sql[, parameters])
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s execute() method with the parameters given, and returns the cursor. | python.library.sqlite3#sqlite3.Connection.execute |
executemany(sql[, parameters])
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executemany() method with the parameters given, and returns the cursor. | python.library.sqlite3#sqlite3.Connection.executemany |
executescript(sql_script)
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executescript() method with the given sql_script, and returns the cursor. | python.library.sqlite3#sqlite3.Connection.executescript |
interrupt()
You can call this method from a different thread to abort any queries that might be executing on the connection. The query will then abort and the caller will get an exception. | python.library.sqlite3#sqlite3.Connection.interrupt |
in_transaction
True if a transaction is active (there are uncommitted changes), False otherwise. Read-only attribute. New in version 3.2. | python.library.sqlite3#sqlite3.Connection.in_transaction |
isolation_level
Get or set the current default isolation level. None for autocommit mode or one of “DEFERRED”, “IMMEDIATE” or “EXCLUSIVE”. See section Controlling Transactions for a more detailed explanation. | python.library.sqlite3#sqlite3.Connection.isolation_level |
iterdump()
Returns an iterator to dump the database in an SQL text format. Useful when saving an in-memory database for later restoration. This function provides the same capabilities as the .dump command in the sqlite3 shell. Example: # Convert file existing_db.db to SQL dump file dump.sql
import sqlite3
con = sqlite3.connect('existing_db.db')
with open('dump.sql', 'w') as f:
for line in con.iterdump():
f.write('%s\n' % line)
con.close() | python.library.sqlite3#sqlite3.Connection.iterdump |
load_extension(path)
This routine loads a SQLite extension from a shared library. You have to enable extension loading with enable_load_extension() before you can use this routine. Loadable extensions are disabled by default. See 1. New in version 3.2. | python.library.sqlite3#sqlite3.Connection.load_extension |
rollback()
This method rolls back any changes to the database since the last call to commit(). | python.library.sqlite3#sqlite3.Connection.rollback |
row_factory
You can change this attribute to a callable that accepts the cursor and the original row as a tuple and will return the real result row. This way, you can implement more advanced ways of returning results, such as returning an object that can also access columns by name. Example: import sqlite3
def dict_factory(cursor, row):
d = {}
for idx, col in enumerate(cursor.description):
d[col[0]] = row[idx]
return d
con = sqlite3.connect(":memory:")
con.row_factory = dict_factory
cur = con.cursor()
cur.execute("select 1 as a")
print(cur.fetchone()["a"])
con.close()
If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting row_factory to the highly-optimized sqlite3.Row type. Row provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution. | python.library.sqlite3#sqlite3.Connection.row_factory |
set_authorizer(authorizer_callback)
This routine registers a callback. The callback is invoked for each attempt to access a column of a table in the database. The callback should return SQLITE_OK if access is allowed, SQLITE_DENY if the entire SQL statement should be aborted with an error and SQLITE_IGNORE if the column should be treated as a NULL value. These constants are available in the sqlite3 module. The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code. Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module. | python.library.sqlite3#sqlite3.Connection.set_authorizer |
set_progress_handler(handler, n)
This routine registers a callback. The callback is invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI. If you want to clear any previously installed progress handler, call the method with None for handler. Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception. | python.library.sqlite3#sqlite3.Connection.set_progress_handler |
set_trace_callback(trace_callback)
Registers trace_callback to be called for each SQL statement that is actually executed by the SQLite backend. The only argument passed to the callback is the statement (as string) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the Python module and the execution of triggers defined in the current database. Passing None as trace_callback will disable the trace callback. New in version 3.3. | python.library.sqlite3#sqlite3.Connection.set_trace_callback |
text_factory
Using this attribute you can control what objects are returned for the TEXT data type. By default, this attribute is set to str and the sqlite3 module will return Unicode objects for TEXT. If you want to return bytestrings instead, you can set it to bytes. You can also set it to any other callable that accepts a single bytestring parameter and returns the resulting object. See the following example code for illustration: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
AUSTRIA = "\xd6sterreich"
# by default, rows are returned as Unicode
cur.execute("select ?", (AUSTRIA,))
row = cur.fetchone()
assert row[0] == AUSTRIA
# but we can make sqlite3 always return bytestrings ...
con.text_factory = bytes
cur.execute("select ?", (AUSTRIA,))
row = cur.fetchone()
assert type(row[0]) is bytes
# the bytestrings will be encoded in UTF-8, unless you stored garbage in the
# database ...
assert row[0] == AUSTRIA.encode("utf-8")
# we can also implement a custom text_factory ...
# here we implement one that appends "foo" to all strings
con.text_factory = lambda x: x.decode("utf-8") + "foo"
cur.execute("select ?", ("bar",))
row = cur.fetchone()
assert row[0] == "barfoo"
con.close() | python.library.sqlite3#sqlite3.Connection.text_factory |
total_changes
Returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened. | python.library.sqlite3#sqlite3.Connection.total_changes |
class sqlite3.Cursor
A Cursor instance has the following attributes and methods.
execute(sql[, parameters])
Executes an SQL statement. Values may be bound to the statement using placeholders. execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call.
executemany(sql, seq_of_parameters)
Executes a parameterized SQL command against all parameter sequences or mappings found in the sequence seq_of_parameters. The sqlite3 module also allows using an iterator yielding parameters instead of a sequence. import sqlite3
class IterChars:
def __init__(self):
self.count = ord('a')
def __iter__(self):
return self
def __next__(self):
if self.count > ord('z'):
raise StopIteration
self.count += 1
return (chr(self.count - 1),) # this is a 1-tuple
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table characters(c)")
theIter = IterChars()
cur.executemany("insert into characters(c) values (?)", theIter)
cur.execute("select c from characters")
print(cur.fetchall())
con.close()
Here’s a shorter example using a generator: import sqlite3
import string
def char_generator():
for c in string.ascii_lowercase:
yield (c,)
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table characters(c)")
cur.executemany("insert into characters(c) values (?)", char_generator())
cur.execute("select c from characters")
print(cur.fetchall())
con.close()
executescript(sql_script)
This is a nonstandard convenience method for executing multiple SQL statements at once. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter. sql_script can be an instance of str. Example: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.executescript("""
create table person(
firstname,
lastname,
age
);
create table book(
title,
author,
published
);
insert into book(title, author, published)
values (
'Dirk Gently''s Holistic Detective Agency',
'Douglas Adams',
1987
);
""")
con.close()
fetchone()
Fetches the next row of a query result set, returning a single sequence, or None when no more data is available.
fetchmany(size=cursor.arraysize)
Fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available. The number of rows to fetch per call is specified by the size parameter. If it is not given, the cursor’s arraysize determines the number of rows to be fetched. The method should try to fetch as many rows as indicated by the size parameter. If this is not possible due to the specified number of rows not being available, fewer rows may be returned. Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next.
fetchall()
Fetches all (remaining) rows of a query result, returning a list. Note that the cursor’s arraysize attribute can affect the performance of this operation. An empty list is returned when no rows are available.
close()
Close the cursor now (rather than whenever __del__ is called). The cursor will be unusable from this point forward; a ProgrammingError exception will be raised if any operation is attempted with the cursor.
rowcount
Although the Cursor class of the sqlite3 module implements this attribute, the database engine’s own support for the determination of “rows affected”/”rows selected” is quirky. For executemany() statements, the number of modifications are summed up into rowcount. As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”. This includes SELECT statements because we cannot determine the number of rows a query produced until all rows were fetched. With SQLite versions before 3.6.5, rowcount is set to 0 if you make a DELETE FROM table without any condition.
lastrowid
This read-only attribute provides the rowid of the last modified row. It is only set if you issued an INSERT or a REPLACE statement using the execute() method. For operations other than INSERT or REPLACE or when executemany() is called, lastrowid is set to None. If the INSERT or REPLACE statement failed to insert the previous successful rowid is returned. Changed in version 3.6: Added support for the REPLACE statement.
arraysize
Read/write attribute that controls the number of rows returned by fetchmany(). The default value is 1 which means a single row would be fetched per call.
description
This read-only attribute provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None. It is set for SELECT statements without any matching rows as well.
connection
This read-only attribute provides the SQLite database Connection used by the Cursor object. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con: >>> con = sqlite3.connect(":memory:")
>>> cur = con.cursor()
>>> cur.connection == con
True | python.library.sqlite3#sqlite3.Cursor |
arraysize
Read/write attribute that controls the number of rows returned by fetchmany(). The default value is 1 which means a single row would be fetched per call. | python.library.sqlite3#sqlite3.Cursor.arraysize |
close()
Close the cursor now (rather than whenever __del__ is called). The cursor will be unusable from this point forward; a ProgrammingError exception will be raised if any operation is attempted with the cursor. | python.library.sqlite3#sqlite3.Cursor.close |
connection
This read-only attribute provides the SQLite database Connection used by the Cursor object. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con: >>> con = sqlite3.connect(":memory:")
>>> cur = con.cursor()
>>> cur.connection == con
True | python.library.sqlite3#sqlite3.Cursor.connection |
description
This read-only attribute provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None. It is set for SELECT statements without any matching rows as well. | python.library.sqlite3#sqlite3.Cursor.description |
execute(sql[, parameters])
Executes an SQL statement. Values may be bound to the statement using placeholders. execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call. | python.library.sqlite3#sqlite3.Cursor.execute |
executemany(sql, seq_of_parameters)
Executes a parameterized SQL command against all parameter sequences or mappings found in the sequence seq_of_parameters. The sqlite3 module also allows using an iterator yielding parameters instead of a sequence. import sqlite3
class IterChars:
def __init__(self):
self.count = ord('a')
def __iter__(self):
return self
def __next__(self):
if self.count > ord('z'):
raise StopIteration
self.count += 1
return (chr(self.count - 1),) # this is a 1-tuple
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table characters(c)")
theIter = IterChars()
cur.executemany("insert into characters(c) values (?)", theIter)
cur.execute("select c from characters")
print(cur.fetchall())
con.close()
Here’s a shorter example using a generator: import sqlite3
import string
def char_generator():
for c in string.ascii_lowercase:
yield (c,)
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table characters(c)")
cur.executemany("insert into characters(c) values (?)", char_generator())
cur.execute("select c from characters")
print(cur.fetchall())
con.close() | python.library.sqlite3#sqlite3.Cursor.executemany |
executescript(sql_script)
This is a nonstandard convenience method for executing multiple SQL statements at once. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter. sql_script can be an instance of str. Example: import sqlite3
con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.executescript("""
create table person(
firstname,
lastname,
age
);
create table book(
title,
author,
published
);
insert into book(title, author, published)
values (
'Dirk Gently''s Holistic Detective Agency',
'Douglas Adams',
1987
);
""")
con.close() | python.library.sqlite3#sqlite3.Cursor.executescript |
fetchall()
Fetches all (remaining) rows of a query result, returning a list. Note that the cursor’s arraysize attribute can affect the performance of this operation. An empty list is returned when no rows are available. | python.library.sqlite3#sqlite3.Cursor.fetchall |
fetchmany(size=cursor.arraysize)
Fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available. The number of rows to fetch per call is specified by the size parameter. If it is not given, the cursor’s arraysize determines the number of rows to be fetched. The method should try to fetch as many rows as indicated by the size parameter. If this is not possible due to the specified number of rows not being available, fewer rows may be returned. Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next. | python.library.sqlite3#sqlite3.Cursor.fetchmany |
fetchone()
Fetches the next row of a query result set, returning a single sequence, or None when no more data is available. | python.library.sqlite3#sqlite3.Cursor.fetchone |
lastrowid
This read-only attribute provides the rowid of the last modified row. It is only set if you issued an INSERT or a REPLACE statement using the execute() method. For operations other than INSERT or REPLACE or when executemany() is called, lastrowid is set to None. If the INSERT or REPLACE statement failed to insert the previous successful rowid is returned. Changed in version 3.6: Added support for the REPLACE statement. | python.library.sqlite3#sqlite3.Cursor.lastrowid |
rowcount
Although the Cursor class of the sqlite3 module implements this attribute, the database engine’s own support for the determination of “rows affected”/”rows selected” is quirky. For executemany() statements, the number of modifications are summed up into rowcount. As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”. This includes SELECT statements because we cannot determine the number of rows a query produced until all rows were fetched. With SQLite versions before 3.6.5, rowcount is set to 0 if you make a DELETE FROM table without any condition. | python.library.sqlite3#sqlite3.Cursor.rowcount |
exception sqlite3.DatabaseError
Exception raised for errors that are related to the database. | python.library.sqlite3#sqlite3.DatabaseError |
sqlite3.enable_callback_tracebacks(flag)
By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on sys.stderr. Use False to disable the feature again. | python.library.sqlite3#sqlite3.enable_callback_tracebacks |
exception sqlite3.Error
The base class of the other exceptions in this module. It is a subclass of Exception. | python.library.sqlite3#sqlite3.Error |
exception sqlite3.IntegrityError
Exception raised when the relational integrity of the database is affected, e.g. a foreign key check fails. It is a subclass of DatabaseError. | python.library.sqlite3#sqlite3.IntegrityError |
exception sqlite3.NotSupportedError
Exception raised in case a method or database API was used which is not supported by the database, e.g. calling the rollback() method on a connection that does not support transaction or has transactions turned off. It is a subclass of DatabaseError. | python.library.sqlite3#sqlite3.NotSupportedError |
exception sqlite3.OperationalError
Exception raised for errors that are related to the database’s operation and not necessarily under the control of the programmer, e.g. an unexpected disconnect occurs, the data source name is not found, a transaction could not be processed, etc. It is a subclass of DatabaseError. | python.library.sqlite3#sqlite3.OperationalError |
sqlite3.PARSE_COLNAMES
This constant is meant to be used with the detect_types parameter of the connect() function. Setting this makes the SQLite interface parse the column name for each column it returns. It will look for a string formed [mytype] in there, and then decide that ‘mytype’ is the type of the column. It will try to find an entry of ‘mytype’ in the converters dictionary and then use the converter function found there to return the value. The column name found in Cursor.description does not include the type, i. e. if you use something like 'as "Expiration date [datetime]"' in your SQL, then we will parse out everything until the first '[' for the column name and strip the preceeding space: the column name would simply be “Expiration date”. | python.library.sqlite3#sqlite3.PARSE_COLNAMES |
sqlite3.PARSE_DECLTYPES
This constant is meant to be used with the detect_types parameter of the connect() function. Setting it makes the sqlite3 module parse the declared type for each column it returns. It will parse out the first word of the declared type, i. e. for “integer primary key”, it will parse out “integer”, or for “number(10)” it will parse out “number”. Then for that column, it will look into the converters dictionary and use the converter function registered for that type there. | python.library.sqlite3#sqlite3.PARSE_DECLTYPES |
exception sqlite3.ProgrammingError
Exception raised for programming errors, e.g. table not found or already exists, syntax error in the SQL statement, wrong number of parameters specified, etc. It is a subclass of DatabaseError. | python.library.sqlite3#sqlite3.ProgrammingError |
sqlite3.register_adapter(type, callable)
Registers a callable to convert the custom Python type type into one of SQLite’s supported types. The callable callable accepts as single parameter the Python value, and must return a value of the following types: int, float, str or bytes. | python.library.sqlite3#sqlite3.register_adapter |
sqlite3.register_converter(typename, callable)
Registers a callable to convert a bytestring from the database into a custom Python type. The callable will be invoked for all database values that are of the type typename. Confer the parameter detect_types of the connect() function for how the type detection works. Note that typename and the name of the type in your query are matched in case-insensitive manner. | python.library.sqlite3#sqlite3.register_converter |
class sqlite3.Row
A Row instance serves as a highly optimized row_factory for Connection objects. It tries to mimic a tuple in most of its features. It supports mapping access by column name and index, iteration, representation, equality testing and len(). If two Row objects have exactly the same columns and their members are equal, they compare equal.
keys()
This method returns a list of column names. Immediately after a query, it is the first member of each tuple in Cursor.description.
Changed in version 3.5: Added support of slicing. | python.library.sqlite3#sqlite3.Row |
keys()
This method returns a list of column names. Immediately after a query, it is the first member of each tuple in Cursor.description. | python.library.sqlite3#sqlite3.Row.keys |
sqlite3.sqlite_version
The version number of the run-time SQLite library, as a string. | python.library.sqlite3#sqlite3.sqlite_version |
sqlite3.sqlite_version_info
The version number of the run-time SQLite library, as a tuple of integers. | python.library.sqlite3#sqlite3.sqlite_version_info |
sqlite3.version
The version number of this module, as a string. This is not the version of the SQLite library. | python.library.sqlite3#sqlite3.version |
sqlite3.version_info
The version number of this module, as a tuple of integers. This is not the version of the SQLite library. | python.library.sqlite3#sqlite3.version_info |
exception sqlite3.Warning
A subclass of Exception. | python.library.sqlite3#sqlite3.Warning |
ssl — TLS/SSL wrapper for socket objects Source code: Lib/ssl.py This module provides access to Transport Layer Security (often known as “Secure Sockets Layer”) encryption and peer authentication facilities for network sockets, both client-side and server-side. This module uses the OpenSSL library. It is available on all modern Unix systems, Windows, Mac OS X, and probably additional platforms, as long as OpenSSL is installed on that platform. Note Some behavior may be platform dependent, since calls are made to the operating system socket APIs. The installed version of OpenSSL may also cause variations in behavior. For example, TLSv1.1 and TLSv1.2 come with openssl version 1.0.1. Warning Don’t use this module without reading the Security considerations. Doing so may lead to a false sense of security, as the default settings of the ssl module are not necessarily appropriate for your application. This section documents the objects and functions in the ssl module; for more general information about TLS, SSL, and certificates, the reader is referred to the documents in the “See Also” section at the bottom. This module provides a class, ssl.SSLSocket, which is derived from the socket.socket type, and provides a socket-like wrapper that also encrypts and decrypts the data going over the socket with SSL. It supports additional methods such as getpeercert(), which retrieves the certificate of the other side of the connection, and cipher(), which retrieves the cipher being used for the secure connection. For more sophisticated applications, the ssl.SSLContext class helps manage settings and certificates, which can then be inherited by SSL sockets created through the SSLContext.wrap_socket() method. Changed in version 3.5.3: Updated to support linking with OpenSSL 1.1.0 Changed in version 3.6: OpenSSL 0.9.8, 1.0.0 and 1.0.1 are deprecated and no longer supported. In the future the ssl module will require at least OpenSSL 1.0.2 or 1.1.0. Functions, Constants, and Exceptions Socket creation Since Python 3.2 and 2.7.9, it is recommended to use the SSLContext.wrap_socket() of an SSLContext instance to wrap sockets as SSLSocket objects. The helper functions create_default_context() returns a new context with secure default settings. The old wrap_socket() function is deprecated since it is both inefficient and has no support for server name indication (SNI) and hostname matching. Client socket example with default context and IPv4/IPv6 dual stack: import socket
import ssl
hostname = 'www.python.org'
context = ssl.create_default_context()
with socket.create_connection((hostname, 443)) as sock:
with context.wrap_socket(sock, server_hostname=hostname) as ssock:
print(ssock.version())
Client socket example with custom context and IPv4: hostname = 'www.python.org'
# PROTOCOL_TLS_CLIENT requires valid cert chain and hostname
context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
context.load_verify_locations('path/to/cabundle.pem')
with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as sock:
with context.wrap_socket(sock, server_hostname=hostname) as ssock:
print(ssock.version())
Server socket example listening on localhost IPv4: context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
context.load_cert_chain('/path/to/certchain.pem', '/path/to/private.key')
with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as sock:
sock.bind(('127.0.0.1', 8443))
sock.listen(5)
with context.wrap_socket(sock, server_side=True) as ssock:
conn, addr = ssock.accept()
...
Context creation A convenience function helps create SSLContext objects for common purposes.
ssl.create_default_context(purpose=Purpose.SERVER_AUTH, cafile=None, capath=None, cadata=None)
Return a new SSLContext object with default settings for the given purpose. The settings are chosen by the ssl module, and usually represent a higher security level than when calling the SSLContext constructor directly. cafile, capath, cadata represent optional CA certificates to trust for certificate verification, as in SSLContext.load_verify_locations(). If all three are None, this function can choose to trust the system’s default CA certificates instead. The settings are: PROTOCOL_TLS, OP_NO_SSLv2, and OP_NO_SSLv3 with high encryption cipher suites without RC4 and without unauthenticated cipher suites. Passing SERVER_AUTH as purpose sets verify_mode to CERT_REQUIRED and either loads CA certificates (when at least one of cafile, capath or cadata is given) or uses SSLContext.load_default_certs() to load default CA certificates. When keylog_filename is supported and the environment variable SSLKEYLOGFILE is set, create_default_context() enables key logging. Note The protocol, options, cipher and other settings may change to more restrictive values anytime without prior deprecation. The values represent a fair balance between compatibility and security. If your application needs specific settings, you should create a SSLContext and apply the settings yourself. Note If you find that when certain older clients or servers attempt to connect with a SSLContext created by this function that they get an error stating “Protocol or cipher suite mismatch”, it may be that they only support SSL3.0 which this function excludes using the OP_NO_SSLv3. SSL3.0 is widely considered to be completely broken. If you still wish to continue to use this function but still allow SSL 3.0 connections you can re-enable them using: ctx = ssl.create_default_context(Purpose.CLIENT_AUTH)
ctx.options &= ~ssl.OP_NO_SSLv3
New in version 3.4. Changed in version 3.4.4: RC4 was dropped from the default cipher string. Changed in version 3.6: ChaCha20/Poly1305 was added to the default cipher string. 3DES was dropped from the default cipher string. Changed in version 3.8: Support for key logging to SSLKEYLOGFILE was added.
Exceptions
exception ssl.SSLError
Raised to signal an error from the underlying SSL implementation (currently provided by the OpenSSL library). This signifies some problem in the higher-level encryption and authentication layer that’s superimposed on the underlying network connection. This error is a subtype of OSError. The error code and message of SSLError instances are provided by the OpenSSL library. Changed in version 3.3: SSLError used to be a subtype of socket.error.
library
A string mnemonic designating the OpenSSL submodule in which the error occurred, such as SSL, PEM or X509. The range of possible values depends on the OpenSSL version. New in version 3.3.
reason
A string mnemonic designating the reason this error occurred, for example CERTIFICATE_VERIFY_FAILED. The range of possible values depends on the OpenSSL version. New in version 3.3.
exception ssl.SSLZeroReturnError
A subclass of SSLError raised when trying to read or write and the SSL connection has been closed cleanly. Note that this doesn’t mean that the underlying transport (read TCP) has been closed. New in version 3.3.
exception ssl.SSLWantReadError
A subclass of SSLError raised by a non-blocking SSL socket when trying to read or write data, but more data needs to be received on the underlying TCP transport before the request can be fulfilled. New in version 3.3.
exception ssl.SSLWantWriteError
A subclass of SSLError raised by a non-blocking SSL socket when trying to read or write data, but more data needs to be sent on the underlying TCP transport before the request can be fulfilled. New in version 3.3.
exception ssl.SSLSyscallError
A subclass of SSLError raised when a system error was encountered while trying to fulfill an operation on a SSL socket. Unfortunately, there is no easy way to inspect the original errno number. New in version 3.3.
exception ssl.SSLEOFError
A subclass of SSLError raised when the SSL connection has been terminated abruptly. Generally, you shouldn’t try to reuse the underlying transport when this error is encountered. New in version 3.3.
exception ssl.SSLCertVerificationError
A subclass of SSLError raised when certificate validation has failed. New in version 3.7.
verify_code
A numeric error number that denotes the verification error.
verify_message
A human readable string of the verification error.
exception ssl.CertificateError
An alias for SSLCertVerificationError. Changed in version 3.7: The exception is now an alias for SSLCertVerificationError.
Random generation
ssl.RAND_bytes(num)
Return num cryptographically strong pseudo-random bytes. Raises an SSLError if the PRNG has not been seeded with enough data or if the operation is not supported by the current RAND method. RAND_status() can be used to check the status of the PRNG and RAND_add() can be used to seed the PRNG. For almost all applications os.urandom() is preferable. Read the Wikipedia article, Cryptographically secure pseudorandom number generator (CSPRNG), to get the requirements of a cryptographically strong generator. New in version 3.3.
ssl.RAND_pseudo_bytes(num)
Return (bytes, is_cryptographic): bytes are num pseudo-random bytes, is_cryptographic is True if the bytes generated are cryptographically strong. Raises an SSLError if the operation is not supported by the current RAND method. Generated pseudo-random byte sequences will be unique if they are of sufficient length, but are not necessarily unpredictable. They can be used for non-cryptographic purposes and for certain purposes in cryptographic protocols, but usually not for key generation etc. For almost all applications os.urandom() is preferable. New in version 3.3. Deprecated since version 3.6: OpenSSL has deprecated ssl.RAND_pseudo_bytes(), use ssl.RAND_bytes() instead.
ssl.RAND_status()
Return True if the SSL pseudo-random number generator has been seeded with ‘enough’ randomness, and False otherwise. You can use ssl.RAND_egd() and ssl.RAND_add() to increase the randomness of the pseudo-random number generator.
ssl.RAND_egd(path)
If you are running an entropy-gathering daemon (EGD) somewhere, and path is the pathname of a socket connection open to it, this will read 256 bytes of randomness from the socket, and add it to the SSL pseudo-random number generator to increase the security of generated secret keys. This is typically only necessary on systems without better sources of randomness. See http://egd.sourceforge.net/ or http://prngd.sourceforge.net/ for sources of entropy-gathering daemons. Availability: not available with LibreSSL and OpenSSL > 1.1.0.
ssl.RAND_add(bytes, entropy)
Mix the given bytes into the SSL pseudo-random number generator. The parameter entropy (a float) is a lower bound on the entropy contained in string (so you can always use 0.0). See RFC 1750 for more information on sources of entropy. Changed in version 3.5: Writable bytes-like object is now accepted.
Certificate handling
ssl.match_hostname(cert, hostname)
Verify that cert (in decoded format as returned by SSLSocket.getpeercert()) matches the given hostname. The rules applied are those for checking the identity of HTTPS servers as outlined in RFC 2818, RFC 5280 and RFC 6125. In addition to HTTPS, this function should be suitable for checking the identity of servers in various SSL-based protocols such as FTPS, IMAPS, POPS and others. CertificateError is raised on failure. On success, the function returns nothing: >>> cert = {'subject': ((('commonName', 'example.com'),),)}
>>> ssl.match_hostname(cert, "example.com")
>>> ssl.match_hostname(cert, "example.org")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/py3k/Lib/ssl.py", line 130, in match_hostname
ssl.CertificateError: hostname 'example.org' doesn't match 'example.com'
New in version 3.2. Changed in version 3.3.3: The function now follows RFC 6125, section 6.4.3 and does neither match multiple wildcards (e.g. *.*.com or *a*.example.org) nor a wildcard inside an internationalized domain names (IDN) fragment. IDN A-labels such as www*.xn--pthon-kva.org are still supported, but x*.python.org no longer matches xn--tda.python.org. Changed in version 3.5: Matching of IP addresses, when present in the subjectAltName field of the certificate, is now supported. Changed in version 3.7: The function is no longer used to TLS connections. Hostname matching is now performed by OpenSSL. Allow wildcard when it is the leftmost and the only character in that segment. Partial wildcards like www*.example.com are no longer supported. Deprecated since version 3.7.
ssl.cert_time_to_seconds(cert_time)
Return the time in seconds since the Epoch, given the cert_time string representing the “notBefore” or “notAfter” date from a certificate in "%b %d %H:%M:%S %Y %Z" strptime format (C locale). Here’s an example: >>> import ssl
>>> timestamp = ssl.cert_time_to_seconds("Jan 5 09:34:43 2018 GMT")
>>> timestamp
1515144883
>>> from datetime import datetime
>>> print(datetime.utcfromtimestamp(timestamp))
2018-01-05 09:34:43
“notBefore” or “notAfter” dates must use GMT (RFC 5280). Changed in version 3.5: Interpret the input time as a time in UTC as specified by ‘GMT’ timezone in the input string. Local timezone was used previously. Return an integer (no fractions of a second in the input format)
ssl.get_server_certificate(addr, ssl_version=PROTOCOL_TLS, ca_certs=None)
Given the address addr of an SSL-protected server, as a (hostname, port-number) pair, fetches the server’s certificate, and returns it as a PEM-encoded string. If ssl_version is specified, uses that version of the SSL protocol to attempt to connect to the server. If ca_certs is specified, it should be a file containing a list of root certificates, the same format as used for the same parameter in SSLContext.wrap_socket(). The call will attempt to validate the server certificate against that set of root certificates, and will fail if the validation attempt fails. Changed in version 3.3: This function is now IPv6-compatible. Changed in version 3.5: The default ssl_version is changed from PROTOCOL_SSLv3 to PROTOCOL_TLS for maximum compatibility with modern servers.
ssl.DER_cert_to_PEM_cert(DER_cert_bytes)
Given a certificate as a DER-encoded blob of bytes, returns a PEM-encoded string version of the same certificate.
ssl.PEM_cert_to_DER_cert(PEM_cert_string)
Given a certificate as an ASCII PEM string, returns a DER-encoded sequence of bytes for that same certificate.
ssl.get_default_verify_paths()
Returns a named tuple with paths to OpenSSL’s default cafile and capath. The paths are the same as used by SSLContext.set_default_verify_paths(). The return value is a named tuple DefaultVerifyPaths:
cafile - resolved path to cafile or None if the file doesn’t exist,
capath - resolved path to capath or None if the directory doesn’t exist,
openssl_cafile_env - OpenSSL’s environment key that points to a cafile,
openssl_cafile - hard coded path to a cafile,
openssl_capath_env - OpenSSL’s environment key that points to a capath,
openssl_capath - hard coded path to a capath directory Availability: LibreSSL ignores the environment vars openssl_cafile_env and openssl_capath_env. New in version 3.4.
ssl.enum_certificates(store_name)
Retrieve certificates from Windows’ system cert store. store_name may be one of CA, ROOT or MY. Windows may provide additional cert stores, too. The function returns a list of (cert_bytes, encoding_type, trust) tuples. The encoding_type specifies the encoding of cert_bytes. It is either x509_asn for X.509 ASN.1 data or pkcs_7_asn for PKCS#7 ASN.1 data. Trust specifies the purpose of the certificate as a set of OIDS or exactly True if the certificate is trustworthy for all purposes. Example: >>> ssl.enum_certificates("CA")
[(b'data...', 'x509_asn', {'1.3.6.1.5.5.7.3.1', '1.3.6.1.5.5.7.3.2'}),
(b'data...', 'x509_asn', True)]
Availability: Windows. New in version 3.4.
ssl.enum_crls(store_name)
Retrieve CRLs from Windows’ system cert store. store_name may be one of CA, ROOT or MY. Windows may provide additional cert stores, too. The function returns a list of (cert_bytes, encoding_type, trust) tuples. The encoding_type specifies the encoding of cert_bytes. It is either x509_asn for X.509 ASN.1 data or pkcs_7_asn for PKCS#7 ASN.1 data. Availability: Windows. New in version 3.4.
ssl.wrap_socket(sock, keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ssl_version=PROTOCOL_TLS, ca_certs=None, do_handshake_on_connect=True, suppress_ragged_eofs=True, ciphers=None)
Takes an instance sock of socket.socket, and returns an instance of ssl.SSLSocket, a subtype of socket.socket, which wraps the underlying socket in an SSL context. sock must be a SOCK_STREAM socket; other socket types are unsupported. Internally, function creates a SSLContext with protocol ssl_version and SSLContext.options set to cert_reqs. If parameters keyfile, certfile, ca_certs or ciphers are set, then the values are passed to SSLContext.load_cert_chain(), SSLContext.load_verify_locations(), and SSLContext.set_ciphers(). The arguments server_side, do_handshake_on_connect, and suppress_ragged_eofs have the same meaning as SSLContext.wrap_socket(). Deprecated since version 3.7: Since Python 3.2 and 2.7.9, it is recommended to use the SSLContext.wrap_socket() instead of wrap_socket(). The top-level function is limited and creates an insecure client socket without server name indication or hostname matching.
Constants All constants are now enum.IntEnum or enum.IntFlag collections. New in version 3.6.
ssl.CERT_NONE
Possible value for SSLContext.verify_mode, or the cert_reqs parameter to wrap_socket(). Except for PROTOCOL_TLS_CLIENT, it is the default mode. With client-side sockets, just about any cert is accepted. Validation errors, such as untrusted or expired cert, are ignored and do not abort the TLS/SSL handshake. In server mode, no certificate is requested from the client, so the client does not send any for client cert authentication. See the discussion of Security considerations below.
ssl.CERT_OPTIONAL
Possible value for SSLContext.verify_mode, or the cert_reqs parameter to wrap_socket(). In client mode, CERT_OPTIONAL has the same meaning as CERT_REQUIRED. It is recommended to use CERT_REQUIRED for client-side sockets instead. In server mode, a client certificate request is sent to the client. The client may either ignore the request or send a certificate in order perform TLS client cert authentication. If the client chooses to send a certificate, it is verified. Any verification error immediately aborts the TLS handshake. Use of this setting requires a valid set of CA certificates to be passed, either to SSLContext.load_verify_locations() or as a value of the ca_certs parameter to wrap_socket().
ssl.CERT_REQUIRED
Possible value for SSLContext.verify_mode, or the cert_reqs parameter to wrap_socket(). In this mode, certificates are required from the other side of the socket connection; an SSLError will be raised if no certificate is provided, or if its validation fails. This mode is not sufficient to verify a certificate in client mode as it does not match hostnames. check_hostname must be enabled as well to verify the authenticity of a cert. PROTOCOL_TLS_CLIENT uses CERT_REQUIRED and enables check_hostname by default. With server socket, this mode provides mandatory TLS client cert authentication. A client certificate request is sent to the client and the client must provide a valid and trusted certificate. Use of this setting requires a valid set of CA certificates to be passed, either to SSLContext.load_verify_locations() or as a value of the ca_certs parameter to wrap_socket().
class ssl.VerifyMode
enum.IntEnum collection of CERT_* constants. New in version 3.6.
ssl.VERIFY_DEFAULT
Possible value for SSLContext.verify_flags. In this mode, certificate revocation lists (CRLs) are not checked. By default OpenSSL does neither require nor verify CRLs. New in version 3.4.
ssl.VERIFY_CRL_CHECK_LEAF
Possible value for SSLContext.verify_flags. In this mode, only the peer cert is checked but none of the intermediate CA certificates. The mode requires a valid CRL that is signed by the peer cert’s issuer (its direct ancestor CA). If no proper CRL has been loaded with SSLContext.load_verify_locations, validation will fail. New in version 3.4.
ssl.VERIFY_CRL_CHECK_CHAIN
Possible value for SSLContext.verify_flags. In this mode, CRLs of all certificates in the peer cert chain are checked. New in version 3.4.
ssl.VERIFY_X509_STRICT
Possible value for SSLContext.verify_flags to disable workarounds for broken X.509 certificates. New in version 3.4.
ssl.VERIFY_X509_TRUSTED_FIRST
Possible value for SSLContext.verify_flags. It instructs OpenSSL to prefer trusted certificates when building the trust chain to validate a certificate. This flag is enabled by default. New in version 3.4.4.
class ssl.VerifyFlags
enum.IntFlag collection of VERIFY_* constants. New in version 3.6.
ssl.PROTOCOL_TLS
Selects the highest protocol version that both the client and server support. Despite the name, this option can select both “SSL” and “TLS” protocols. New in version 3.6.
ssl.PROTOCOL_TLS_CLIENT
Auto-negotiate the highest protocol version like PROTOCOL_TLS, but only support client-side SSLSocket connections. The protocol enables CERT_REQUIRED and check_hostname by default. New in version 3.6.
ssl.PROTOCOL_TLS_SERVER
Auto-negotiate the highest protocol version like PROTOCOL_TLS, but only support server-side SSLSocket connections. New in version 3.6.
ssl.PROTOCOL_SSLv23
Alias for PROTOCOL_TLS. Deprecated since version 3.6: Use PROTOCOL_TLS instead.
ssl.PROTOCOL_SSLv2
Selects SSL version 2 as the channel encryption protocol. This protocol is not available if OpenSSL is compiled with the OPENSSL_NO_SSL2 flag. Warning SSL version 2 is insecure. Its use is highly discouraged. Deprecated since version 3.6: OpenSSL has removed support for SSLv2.
ssl.PROTOCOL_SSLv3
Selects SSL version 3 as the channel encryption protocol. This protocol is not be available if OpenSSL is compiled with the OPENSSL_NO_SSLv3 flag. Warning SSL version 3 is insecure. Its use is highly discouraged. Deprecated since version 3.6: OpenSSL has deprecated all version specific protocols. Use the default protocol PROTOCOL_TLS with flags like OP_NO_SSLv3 instead.
ssl.PROTOCOL_TLSv1
Selects TLS version 1.0 as the channel encryption protocol. Deprecated since version 3.6: OpenSSL has deprecated all version specific protocols. Use the default protocol PROTOCOL_TLS with flags like OP_NO_SSLv3 instead.
ssl.PROTOCOL_TLSv1_1
Selects TLS version 1.1 as the channel encryption protocol. Available only with openssl version 1.0.1+. New in version 3.4. Deprecated since version 3.6: OpenSSL has deprecated all version specific protocols. Use the default protocol PROTOCOL_TLS with flags like OP_NO_SSLv3 instead.
ssl.PROTOCOL_TLSv1_2
Selects TLS version 1.2 as the channel encryption protocol. This is the most modern version, and probably the best choice for maximum protection, if both sides can speak it. Available only with openssl version 1.0.1+. New in version 3.4. Deprecated since version 3.6: OpenSSL has deprecated all version specific protocols. Use the default protocol PROTOCOL_TLS with flags like OP_NO_SSLv3 instead.
ssl.OP_ALL
Enables workarounds for various bugs present in other SSL implementations. This option is set by default. It does not necessarily set the same flags as OpenSSL’s SSL_OP_ALL constant. New in version 3.2.
ssl.OP_NO_SSLv2
Prevents an SSLv2 connection. This option is only applicable in conjunction with PROTOCOL_TLS. It prevents the peers from choosing SSLv2 as the protocol version. New in version 3.2. Deprecated since version 3.6: SSLv2 is deprecated
ssl.OP_NO_SSLv3
Prevents an SSLv3 connection. This option is only applicable in conjunction with PROTOCOL_TLS. It prevents the peers from choosing SSLv3 as the protocol version. New in version 3.2. Deprecated since version 3.6: SSLv3 is deprecated
ssl.OP_NO_TLSv1
Prevents a TLSv1 connection. This option is only applicable in conjunction with PROTOCOL_TLS. It prevents the peers from choosing TLSv1 as the protocol version. New in version 3.2. Deprecated since version 3.7: The option is deprecated since OpenSSL 1.1.0, use the new SSLContext.minimum_version and SSLContext.maximum_version instead.
ssl.OP_NO_TLSv1_1
Prevents a TLSv1.1 connection. This option is only applicable in conjunction with PROTOCOL_TLS. It prevents the peers from choosing TLSv1.1 as the protocol version. Available only with openssl version 1.0.1+. New in version 3.4. Deprecated since version 3.7: The option is deprecated since OpenSSL 1.1.0.
ssl.OP_NO_TLSv1_2
Prevents a TLSv1.2 connection. This option is only applicable in conjunction with PROTOCOL_TLS. It prevents the peers from choosing TLSv1.2 as the protocol version. Available only with openssl version 1.0.1+. New in version 3.4. Deprecated since version 3.7: The option is deprecated since OpenSSL 1.1.0.
ssl.OP_NO_TLSv1_3
Prevents a TLSv1.3 connection. This option is only applicable in conjunction with PROTOCOL_TLS. It prevents the peers from choosing TLSv1.3 as the protocol version. TLS 1.3 is available with OpenSSL 1.1.1 or later. When Python has been compiled against an older version of OpenSSL, the flag defaults to 0. New in version 3.7. Deprecated since version 3.7: The option is deprecated since OpenSSL 1.1.0. It was added to 2.7.15, 3.6.3 and 3.7.0 for backwards compatibility with OpenSSL 1.0.2.
ssl.OP_NO_RENEGOTIATION
Disable all renegotiation in TLSv1.2 and earlier. Do not send HelloRequest messages, and ignore renegotiation requests via ClientHello. This option is only available with OpenSSL 1.1.0h and later. New in version 3.7.
ssl.OP_CIPHER_SERVER_PREFERENCE
Use the server’s cipher ordering preference, rather than the client’s. This option has no effect on client sockets and SSLv2 server sockets. New in version 3.3.
ssl.OP_SINGLE_DH_USE
Prevents re-use of the same DH key for distinct SSL sessions. This improves forward secrecy but requires more computational resources. This option only applies to server sockets. New in version 3.3.
ssl.OP_SINGLE_ECDH_USE
Prevents re-use of the same ECDH key for distinct SSL sessions. This improves forward secrecy but requires more computational resources. This option only applies to server sockets. New in version 3.3.
ssl.OP_ENABLE_MIDDLEBOX_COMPAT
Send dummy Change Cipher Spec (CCS) messages in TLS 1.3 handshake to make a TLS 1.3 connection look more like a TLS 1.2 connection. This option is only available with OpenSSL 1.1.1 and later. New in version 3.8.
ssl.OP_NO_COMPRESSION
Disable compression on the SSL channel. This is useful if the application protocol supports its own compression scheme. This option is only available with OpenSSL 1.0.0 and later. New in version 3.3.
class ssl.Options
enum.IntFlag collection of OP_* constants.
ssl.OP_NO_TICKET
Prevent client side from requesting a session ticket. New in version 3.6.
ssl.OP_IGNORE_UNEXPECTED_EOF
Ignore unexpected shutdown of TLS connections. This option is only available with OpenSSL 3.0.0 and later. New in version 3.10.
ssl.HAS_ALPN
Whether the OpenSSL library has built-in support for the Application-Layer Protocol Negotiation TLS extension as described in RFC 7301. New in version 3.5.
ssl.HAS_NEVER_CHECK_COMMON_NAME
Whether the OpenSSL library has built-in support not checking subject common name and SSLContext.hostname_checks_common_name is writeable. New in version 3.7.
ssl.HAS_ECDH
Whether the OpenSSL library has built-in support for the Elliptic Curve-based Diffie-Hellman key exchange. This should be true unless the feature was explicitly disabled by the distributor. New in version 3.3.
ssl.HAS_SNI
Whether the OpenSSL library has built-in support for the Server Name Indication extension (as defined in RFC 6066). New in version 3.2.
ssl.HAS_NPN
Whether the OpenSSL library has built-in support for the Next Protocol Negotiation as described in the Application Layer Protocol Negotiation. When true, you can use the SSLContext.set_npn_protocols() method to advertise which protocols you want to support. New in version 3.3.
ssl.HAS_SSLv2
Whether the OpenSSL library has built-in support for the SSL 2.0 protocol. New in version 3.7.
ssl.HAS_SSLv3
Whether the OpenSSL library has built-in support for the SSL 3.0 protocol. New in version 3.7.
ssl.HAS_TLSv1
Whether the OpenSSL library has built-in support for the TLS 1.0 protocol. New in version 3.7.
ssl.HAS_TLSv1_1
Whether the OpenSSL library has built-in support for the TLS 1.1 protocol. New in version 3.7.
ssl.HAS_TLSv1_2
Whether the OpenSSL library has built-in support for the TLS 1.2 protocol. New in version 3.7.
ssl.HAS_TLSv1_3
Whether the OpenSSL library has built-in support for the TLS 1.3 protocol. New in version 3.7.
ssl.CHANNEL_BINDING_TYPES
List of supported TLS channel binding types. Strings in this list can be used as arguments to SSLSocket.get_channel_binding(). New in version 3.3.
ssl.OPENSSL_VERSION
The version string of the OpenSSL library loaded by the interpreter: >>> ssl.OPENSSL_VERSION
'OpenSSL 1.0.2k 26 Jan 2017'
New in version 3.2.
ssl.OPENSSL_VERSION_INFO
A tuple of five integers representing version information about the OpenSSL library: >>> ssl.OPENSSL_VERSION_INFO
(1, 0, 2, 11, 15)
New in version 3.2.
ssl.OPENSSL_VERSION_NUMBER
The raw version number of the OpenSSL library, as a single integer: >>> ssl.OPENSSL_VERSION_NUMBER
268443839
>>> hex(ssl.OPENSSL_VERSION_NUMBER)
'0x100020bf'
New in version 3.2.
ssl.ALERT_DESCRIPTION_HANDSHAKE_FAILURE
ssl.ALERT_DESCRIPTION_INTERNAL_ERROR
ALERT_DESCRIPTION_*
Alert Descriptions from RFC 5246 and others. The IANA TLS Alert Registry contains this list and references to the RFCs where their meaning is defined. Used as the return value of the callback function in SSLContext.set_servername_callback(). New in version 3.4.
class ssl.AlertDescription
enum.IntEnum collection of ALERT_DESCRIPTION_* constants. New in version 3.6.
Purpose.SERVER_AUTH
Option for create_default_context() and SSLContext.load_default_certs(). This value indicates that the context may be used to authenticate Web servers (therefore, it will be used to create client-side sockets). New in version 3.4.
Purpose.CLIENT_AUTH
Option for create_default_context() and SSLContext.load_default_certs(). This value indicates that the context may be used to authenticate Web clients (therefore, it will be used to create server-side sockets). New in version 3.4.
class ssl.SSLErrorNumber
enum.IntEnum collection of SSL_ERROR_* constants. New in version 3.6.
class ssl.TLSVersion
enum.IntEnum collection of SSL and TLS versions for SSLContext.maximum_version and SSLContext.minimum_version. New in version 3.7.
TLSVersion.MINIMUM_SUPPORTED
TLSVersion.MAXIMUM_SUPPORTED
The minimum or maximum supported SSL or TLS version. These are magic constants. Their values don’t reflect the lowest and highest available TLS/SSL versions.
TLSVersion.SSLv3
TLSVersion.TLSv1
TLSVersion.TLSv1_1
TLSVersion.TLSv1_2
TLSVersion.TLSv1_3
SSL 3.0 to TLS 1.3.
SSL Sockets
class ssl.SSLSocket(socket.socket)
SSL sockets provide the following methods of Socket Objects: accept() bind() close() connect() detach() fileno()
getpeername(), getsockname()
getsockopt(), setsockopt()
gettimeout(), settimeout(), setblocking()
listen() makefile()
recv(), recv_into() (but passing a non-zero flags argument is not allowed)
send(), sendall() (with the same limitation)
sendfile() (but os.sendfile will be used for plain-text sockets only, else send() will be used) shutdown() However, since the SSL (and TLS) protocol has its own framing atop of TCP, the SSL sockets abstraction can, in certain respects, diverge from the specification of normal, OS-level sockets. See especially the notes on non-blocking sockets. Instances of SSLSocket must be created using the SSLContext.wrap_socket() method. Changed in version 3.5: The sendfile() method was added. Changed in version 3.5: The shutdown() does not reset the socket timeout each time bytes are received or sent. The socket timeout is now to maximum total duration of the shutdown. Deprecated since version 3.6: It is deprecated to create a SSLSocket instance directly, use SSLContext.wrap_socket() to wrap a socket. Changed in version 3.7: SSLSocket instances must to created with wrap_socket(). In earlier versions, it was possible to create instances directly. This was never documented or officially supported.
SSL sockets also have the following additional methods and attributes:
SSLSocket.read(len=1024, buffer=None)
Read up to len bytes of data from the SSL socket and return the result as a bytes instance. If buffer is specified, then read into the buffer instead, and return the number of bytes read. Raise SSLWantReadError or SSLWantWriteError if the socket is non-blocking and the read would block. As at any time a re-negotiation is possible, a call to read() can also cause write operations. Changed in version 3.5: The socket timeout is no more reset each time bytes are received or sent. The socket timeout is now to maximum total duration to read up to len bytes. Deprecated since version 3.6: Use recv() instead of read().
SSLSocket.write(buf)
Write buf to the SSL socket and return the number of bytes written. The buf argument must be an object supporting the buffer interface. Raise SSLWantReadError or SSLWantWriteError if the socket is non-blocking and the write would block. As at any time a re-negotiation is possible, a call to write() can also cause read operations. Changed in version 3.5: The socket timeout is no more reset each time bytes are received or sent. The socket timeout is now to maximum total duration to write buf. Deprecated since version 3.6: Use send() instead of write().
Note The read() and write() methods are the low-level methods that read and write unencrypted, application-level data and decrypt/encrypt it to encrypted, wire-level data. These methods require an active SSL connection, i.e. the handshake was completed and SSLSocket.unwrap() was not called. Normally you should use the socket API methods like recv() and send() instead of these methods.
SSLSocket.do_handshake()
Perform the SSL setup handshake. Changed in version 3.4: The handshake method also performs match_hostname() when the check_hostname attribute of the socket’s context is true. Changed in version 3.5: The socket timeout is no more reset each time bytes are received or sent. The socket timeout is now to maximum total duration of the handshake. Changed in version 3.7: Hostname or IP address is matched by OpenSSL during handshake. The function match_hostname() is no longer used. In case OpenSSL refuses a hostname or IP address, the handshake is aborted early and a TLS alert message is send to the peer.
SSLSocket.getpeercert(binary_form=False)
If there is no certificate for the peer on the other end of the connection, return None. If the SSL handshake hasn’t been done yet, raise ValueError. If the binary_form parameter is False, and a certificate was received from the peer, this method returns a dict instance. If the certificate was not validated, the dict is empty. If the certificate was validated, it returns a dict with several keys, amongst them subject (the principal for which the certificate was issued) and issuer (the principal issuing the certificate). If a certificate contains an instance of the Subject Alternative Name extension (see RFC 3280), there will also be a subjectAltName key in the dictionary. The subject and issuer fields are tuples containing the sequence of relative distinguished names (RDNs) given in the certificate’s data structure for the respective fields, and each RDN is a sequence of name-value pairs. Here is a real-world example: {'issuer': ((('countryName', 'IL'),),
(('organizationName', 'StartCom Ltd.'),),
(('organizationalUnitName',
'Secure Digital Certificate Signing'),),
(('commonName',
'StartCom Class 2 Primary Intermediate Server CA'),)),
'notAfter': 'Nov 22 08:15:19 2013 GMT',
'notBefore': 'Nov 21 03:09:52 2011 GMT',
'serialNumber': '95F0',
'subject': ((('description', '571208-SLe257oHY9fVQ07Z'),),
(('countryName', 'US'),),
(('stateOrProvinceName', 'California'),),
(('localityName', 'San Francisco'),),
(('organizationName', 'Electronic Frontier Foundation, Inc.'),),
(('commonName', '*.eff.org'),),
(('emailAddress', 'hostmaster@eff.org'),)),
'subjectAltName': (('DNS', '*.eff.org'), ('DNS', 'eff.org')),
'version': 3}
Note To validate a certificate for a particular service, you can use the match_hostname() function. If the binary_form parameter is True, and a certificate was provided, this method returns the DER-encoded form of the entire certificate as a sequence of bytes, or None if the peer did not provide a certificate. Whether the peer provides a certificate depends on the SSL socket’s role: for a client SSL socket, the server will always provide a certificate, regardless of whether validation was required; for a server SSL socket, the client will only provide a certificate when requested by the server; therefore getpeercert() will return None if you used CERT_NONE (rather than CERT_OPTIONAL or CERT_REQUIRED). Changed in version 3.2: The returned dictionary includes additional items such as issuer and notBefore. Changed in version 3.4: ValueError is raised when the handshake isn’t done. The returned dictionary includes additional X509v3 extension items such as crlDistributionPoints, caIssuers and OCSP URIs. Changed in version 3.9: IPv6 address strings no longer have a trailing new line.
SSLSocket.cipher()
Returns a three-value tuple containing the name of the cipher being used, the version of the SSL protocol that defines its use, and the number of secret bits being used. If no connection has been established, returns None.
SSLSocket.shared_ciphers()
Return the list of ciphers shared by the client during the handshake. Each entry of the returned list is a three-value tuple containing the name of the cipher, the version of the SSL protocol that defines its use, and the number of secret bits the cipher uses. shared_ciphers() returns None if no connection has been established or the socket is a client socket. New in version 3.5.
SSLSocket.compression()
Return the compression algorithm being used as a string, or None if the connection isn’t compressed. If the higher-level protocol supports its own compression mechanism, you can use OP_NO_COMPRESSION to disable SSL-level compression. New in version 3.3.
SSLSocket.get_channel_binding(cb_type="tls-unique")
Get channel binding data for current connection, as a bytes object. Returns None if not connected or the handshake has not been completed. The cb_type parameter allow selection of the desired channel binding type. Valid channel binding types are listed in the CHANNEL_BINDING_TYPES list. Currently only the ‘tls-unique’ channel binding, defined by RFC 5929, is supported. ValueError will be raised if an unsupported channel binding type is requested. New in version 3.3.
SSLSocket.selected_alpn_protocol()
Return the protocol that was selected during the TLS handshake. If SSLContext.set_alpn_protocols() was not called, if the other party does not support ALPN, if this socket does not support any of the client’s proposed protocols, or if the handshake has not happened yet, None is returned. New in version 3.5.
SSLSocket.selected_npn_protocol()
Return the higher-level protocol that was selected during the TLS/SSL handshake. If SSLContext.set_npn_protocols() was not called, or if the other party does not support NPN, or if the handshake has not yet happened, this will return None. New in version 3.3.
SSLSocket.unwrap()
Performs the SSL shutdown handshake, which removes the TLS layer from the underlying socket, and returns the underlying socket object. This can be used to go from encrypted operation over a connection to unencrypted. The returned socket should always be used for further communication with the other side of the connection, rather than the original socket.
SSLSocket.verify_client_post_handshake()
Requests post-handshake authentication (PHA) from a TLS 1.3 client. PHA can only be initiated for a TLS 1.3 connection from a server-side socket, after the initial TLS handshake and with PHA enabled on both sides, see SSLContext.post_handshake_auth. The method does not perform a cert exchange immediately. The server-side sends a CertificateRequest during the next write event and expects the client to respond with a certificate on the next read event. If any precondition isn’t met (e.g. not TLS 1.3, PHA not enabled), an SSLError is raised. Note Only available with OpenSSL 1.1.1 and TLS 1.3 enabled. Without TLS 1.3 support, the method raises NotImplementedError. New in version 3.8.
SSLSocket.version()
Return the actual SSL protocol version negotiated by the connection as a string, or None is no secure connection is established. As of this writing, possible return values include "SSLv2", "SSLv3", "TLSv1", "TLSv1.1" and "TLSv1.2". Recent OpenSSL versions may define more return values. New in version 3.5.
SSLSocket.pending()
Returns the number of already decrypted bytes available for read, pending on the connection.
SSLSocket.context
The SSLContext object this SSL socket is tied to. If the SSL socket was created using the deprecated wrap_socket() function (rather than SSLContext.wrap_socket()), this is a custom context object created for this SSL socket. New in version 3.2.
SSLSocket.server_side
A boolean which is True for server-side sockets and False for client-side sockets. New in version 3.2.
SSLSocket.server_hostname
Hostname of the server: str type, or None for server-side socket or if the hostname was not specified in the constructor. New in version 3.2. Changed in version 3.7: The attribute is now always ASCII text. When server_hostname is an internationalized domain name (IDN), this attribute now stores the A-label form ("xn--pythn-mua.org"), rather than the U-label form ("pythön.org").
SSLSocket.session
The SSLSession for this SSL connection. The session is available for client and server side sockets after the TLS handshake has been performed. For client sockets the session can be set before do_handshake() has been called to reuse a session. New in version 3.6.
SSLSocket.session_reused
New in version 3.6.
SSL Contexts New in version 3.2. An SSL context holds various data longer-lived than single SSL connections, such as SSL configuration options, certificate(s) and private key(s). It also manages a cache of SSL sessions for server-side sockets, in order to speed up repeated connections from the same clients.
class ssl.SSLContext(protocol=PROTOCOL_TLS)
Create a new SSL context. You may pass protocol which must be one of the PROTOCOL_* constants defined in this module. The parameter specifies which version of the SSL protocol to use. Typically, the server chooses a particular protocol version, and the client must adapt to the server’s choice. Most of the versions are not interoperable with the other versions. If not specified, the default is PROTOCOL_TLS; it provides the most compatibility with other versions. Here’s a table showing which versions in a client (down the side) can connect to which versions in a server (along the top):
client / server SSLv2 SSLv3 TLS 3 TLSv1 TLSv1.1 TLSv1.2
SSLv2 yes no no 1 no no no
SSLv3 no yes no 2 no no no
TLS (SSLv23) 3 no 1 no 2 yes yes yes yes
TLSv1 no no yes yes no no
TLSv1.1 no no yes no yes no
TLSv1.2 no no yes no no yes Footnotes
1(1,2)
SSLContext disables SSLv2 with OP_NO_SSLv2 by default.
2(1,2)
SSLContext disables SSLv3 with OP_NO_SSLv3 by default.
3(1,2)
TLS 1.3 protocol will be available with PROTOCOL_TLS in OpenSSL >= 1.1.1. There is no dedicated PROTOCOL constant for just TLS 1.3. See also create_default_context() lets the ssl module choose security settings for a given purpose. Changed in version 3.6: The context is created with secure default values. The options OP_NO_COMPRESSION, OP_CIPHER_SERVER_PREFERENCE, OP_SINGLE_DH_USE, OP_SINGLE_ECDH_USE, OP_NO_SSLv2 (except for PROTOCOL_SSLv2), and OP_NO_SSLv3 (except for PROTOCOL_SSLv3) are set by default. The initial cipher suite list contains only HIGH ciphers, no NULL ciphers and no MD5 ciphers (except for PROTOCOL_SSLv2).
SSLContext objects have the following methods and attributes:
SSLContext.cert_store_stats()
Get statistics about quantities of loaded X.509 certificates, count of X.509 certificates flagged as CA certificates and certificate revocation lists as dictionary. Example for a context with one CA cert and one other cert: >>> context.cert_store_stats()
{'crl': 0, 'x509_ca': 1, 'x509': 2}
New in version 3.4.
SSLContext.load_cert_chain(certfile, keyfile=None, password=None)
Load a private key and the corresponding certificate. The certfile string must be the path to a single file in PEM format containing the certificate as well as any number of CA certificates needed to establish the certificate’s authenticity. The keyfile string, if present, must point to a file containing the private key in. Otherwise the private key will be taken from certfile as well. See the discussion of Certificates for more information on how the certificate is stored in the certfile. The password argument may be a function to call to get the password for decrypting the private key. It will only be called if the private key is encrypted and a password is necessary. It will be called with no arguments, and it should return a string, bytes, or bytearray. If the return value is a string it will be encoded as UTF-8 before using it to decrypt the key. Alternatively a string, bytes, or bytearray value may be supplied directly as the password argument. It will be ignored if the private key is not encrypted and no password is needed. If the password argument is not specified and a password is required, OpenSSL’s built-in password prompting mechanism will be used to interactively prompt the user for a password. An SSLError is raised if the private key doesn’t match with the certificate. Changed in version 3.3: New optional argument password.
SSLContext.load_default_certs(purpose=Purpose.SERVER_AUTH)
Load a set of default “certification authority” (CA) certificates from default locations. On Windows it loads CA certs from the CA and ROOT system stores. On other systems it calls SSLContext.set_default_verify_paths(). In the future the method may load CA certificates from other locations, too. The purpose flag specifies what kind of CA certificates are loaded. The default settings Purpose.SERVER_AUTH loads certificates, that are flagged and trusted for TLS web server authentication (client side sockets). Purpose.CLIENT_AUTH loads CA certificates for client certificate verification on the server side. New in version 3.4.
SSLContext.load_verify_locations(cafile=None, capath=None, cadata=None)
Load a set of “certification authority” (CA) certificates used to validate other peers’ certificates when verify_mode is other than CERT_NONE. At least one of cafile or capath must be specified. This method can also load certification revocation lists (CRLs) in PEM or DER format. In order to make use of CRLs, SSLContext.verify_flags must be configured properly. The cafile string, if present, is the path to a file of concatenated CA certificates in PEM format. See the discussion of Certificates for more information about how to arrange the certificates in this file. The capath string, if present, is the path to a directory containing several CA certificates in PEM format, following an OpenSSL specific layout. The cadata object, if present, is either an ASCII string of one or more PEM-encoded certificates or a bytes-like object of DER-encoded certificates. Like with capath extra lines around PEM-encoded certificates are ignored but at least one certificate must be present. Changed in version 3.4: New optional argument cadata
SSLContext.get_ca_certs(binary_form=False)
Get a list of loaded “certification authority” (CA) certificates. If the binary_form parameter is False each list entry is a dict like the output of SSLSocket.getpeercert(). Otherwise the method returns a list of DER-encoded certificates. The returned list does not contain certificates from capath unless a certificate was requested and loaded by a SSL connection. Note Certificates in a capath directory aren’t loaded unless they have been used at least once. New in version 3.4.
SSLContext.get_ciphers()
Get a list of enabled ciphers. The list is in order of cipher priority. See SSLContext.set_ciphers(). Example: >>> ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
>>> ctx.set_ciphers('ECDHE+AESGCM:!ECDSA')
>>> ctx.get_ciphers() # OpenSSL 1.0.x
[{'alg_bits': 256,
'description': 'ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=RSA '
'Enc=AESGCM(256) Mac=AEAD',
'id': 50380848,
'name': 'ECDHE-RSA-AES256-GCM-SHA384',
'protocol': 'TLSv1/SSLv3',
'strength_bits': 256},
{'alg_bits': 128,
'description': 'ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=RSA '
'Enc=AESGCM(128) Mac=AEAD',
'id': 50380847,
'name': 'ECDHE-RSA-AES128-GCM-SHA256',
'protocol': 'TLSv1/SSLv3',
'strength_bits': 128}]
On OpenSSL 1.1 and newer the cipher dict contains additional fields: >>> ctx.get_ciphers() # OpenSSL 1.1+
[{'aead': True,
'alg_bits': 256,
'auth': 'auth-rsa',
'description': 'ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=RSA '
'Enc=AESGCM(256) Mac=AEAD',
'digest': None,
'id': 50380848,
'kea': 'kx-ecdhe',
'name': 'ECDHE-RSA-AES256-GCM-SHA384',
'protocol': 'TLSv1.2',
'strength_bits': 256,
'symmetric': 'aes-256-gcm'},
{'aead': True,
'alg_bits': 128,
'auth': 'auth-rsa',
'description': 'ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH Au=RSA '
'Enc=AESGCM(128) Mac=AEAD',
'digest': None,
'id': 50380847,
'kea': 'kx-ecdhe',
'name': 'ECDHE-RSA-AES128-GCM-SHA256',
'protocol': 'TLSv1.2',
'strength_bits': 128,
'symmetric': 'aes-128-gcm'}]
Availability: OpenSSL 1.0.2+. New in version 3.6.
SSLContext.set_default_verify_paths()
Load a set of default “certification authority” (CA) certificates from a filesystem path defined when building the OpenSSL library. Unfortunately, there’s no easy way to know whether this method succeeds: no error is returned if no certificates are to be found. When the OpenSSL library is provided as part of the operating system, though, it is likely to be configured properly.
SSLContext.set_ciphers(ciphers)
Set the available ciphers for sockets created with this context. It should be a string in the OpenSSL cipher list format. If no cipher can be selected (because compile-time options or other configuration forbids use of all the specified ciphers), an SSLError will be raised. Note when connected, the SSLSocket.cipher() method of SSL sockets will give the currently selected cipher. OpenSSL 1.1.1 has TLS 1.3 cipher suites enabled by default. The suites cannot be disabled with set_ciphers().
SSLContext.set_alpn_protocols(protocols)
Specify which protocols the socket should advertise during the SSL/TLS handshake. It should be a list of ASCII strings, like ['http/1.1',
'spdy/2'], ordered by preference. The selection of a protocol will happen during the handshake, and will play out according to RFC 7301. After a successful handshake, the SSLSocket.selected_alpn_protocol() method will return the agreed-upon protocol. This method will raise NotImplementedError if HAS_ALPN is False. OpenSSL 1.1.0 to 1.1.0e will abort the handshake and raise SSLError when both sides support ALPN but cannot agree on a protocol. 1.1.0f+ behaves like 1.0.2, SSLSocket.selected_alpn_protocol() returns None. New in version 3.5.
SSLContext.set_npn_protocols(protocols)
Specify which protocols the socket should advertise during the SSL/TLS handshake. It should be a list of strings, like ['http/1.1', 'spdy/2'], ordered by preference. The selection of a protocol will happen during the handshake, and will play out according to the Application Layer Protocol Negotiation. After a successful handshake, the SSLSocket.selected_npn_protocol() method will return the agreed-upon protocol. This method will raise NotImplementedError if HAS_NPN is False. New in version 3.3.
SSLContext.sni_callback
Register a callback function that will be called after the TLS Client Hello handshake message has been received by the SSL/TLS server when the TLS client specifies a server name indication. The server name indication mechanism is specified in RFC 6066 section 3 - Server Name Indication. Only one callback can be set per SSLContext. If sni_callback is set to None then the callback is disabled. Calling this function a subsequent time will disable the previously registered callback. The callback function will be called with three arguments; the first being the ssl.SSLSocket, the second is a string that represents the server name that the client is intending to communicate (or None if the TLS Client Hello does not contain a server name) and the third argument is the original SSLContext. The server name argument is text. For internationalized domain name, the server name is an IDN A-label ("xn--pythn-mua.org"). A typical use of this callback is to change the ssl.SSLSocket’s SSLSocket.context attribute to a new object of type SSLContext representing a certificate chain that matches the server name. Due to the early negotiation phase of the TLS connection, only limited methods and attributes are usable like SSLSocket.selected_alpn_protocol() and SSLSocket.context. SSLSocket.getpeercert(), SSLSocket.getpeercert(), SSLSocket.cipher() and SSLSocket.compress() methods require that the TLS connection has progressed beyond the TLS Client Hello and therefore will not contain return meaningful values nor can they be called safely. The sni_callback function must return None to allow the TLS negotiation to continue. If a TLS failure is required, a constant ALERT_DESCRIPTION_* can be returned. Other return values will result in a TLS fatal error with ALERT_DESCRIPTION_INTERNAL_ERROR. If an exception is raised from the sni_callback function the TLS connection will terminate with a fatal TLS alert message ALERT_DESCRIPTION_HANDSHAKE_FAILURE. This method will raise NotImplementedError if the OpenSSL library had OPENSSL_NO_TLSEXT defined when it was built. New in version 3.7.
SSLContext.set_servername_callback(server_name_callback)
This is a legacy API retained for backwards compatibility. When possible, you should use sni_callback instead. The given server_name_callback is similar to sni_callback, except that when the server hostname is an IDN-encoded internationalized domain name, the server_name_callback receives a decoded U-label ("pythön.org"). If there is an decoding error on the server name, the TLS connection will terminate with an ALERT_DESCRIPTION_INTERNAL_ERROR fatal TLS alert message to the client. New in version 3.4.
SSLContext.load_dh_params(dhfile)
Load the key generation parameters for Diffie-Hellman (DH) key exchange. Using DH key exchange improves forward secrecy at the expense of computational resources (both on the server and on the client). The dhfile parameter should be the path to a file containing DH parameters in PEM format. This setting doesn’t apply to client sockets. You can also use the OP_SINGLE_DH_USE option to further improve security. New in version 3.3.
SSLContext.set_ecdh_curve(curve_name)
Set the curve name for Elliptic Curve-based Diffie-Hellman (ECDH) key exchange. ECDH is significantly faster than regular DH while arguably as secure. The curve_name parameter should be a string describing a well-known elliptic curve, for example prime256v1 for a widely supported curve. This setting doesn’t apply to client sockets. You can also use the OP_SINGLE_ECDH_USE option to further improve security. This method is not available if HAS_ECDH is False. New in version 3.3. See also SSL/TLS & Perfect Forward Secrecy
Vincent Bernat.
SSLContext.wrap_socket(sock, server_side=False, do_handshake_on_connect=True, suppress_ragged_eofs=True, server_hostname=None, session=None)
Wrap an existing Python socket sock and return an instance of SSLContext.sslsocket_class (default SSLSocket). The returned SSL socket is tied to the context, its settings and certificates. sock must be a SOCK_STREAM socket; other socket types are unsupported. The parameter server_side is a boolean which identifies whether server-side or client-side behavior is desired from this socket. For client-side sockets, the context construction is lazy; if the underlying socket isn’t connected yet, the context construction will be performed after connect() is called on the socket. For server-side sockets, if the socket has no remote peer, it is assumed to be a listening socket, and the server-side SSL wrapping is automatically performed on client connections accepted via the accept() method. The method may raise SSLError. On client connections, the optional parameter server_hostname specifies the hostname of the service which we are connecting to. This allows a single server to host multiple SSL-based services with distinct certificates, quite similarly to HTTP virtual hosts. Specifying server_hostname will raise a ValueError if server_side is true. The parameter do_handshake_on_connect specifies whether to do the SSL handshake automatically after doing a socket.connect(), or whether the application program will call it explicitly, by invoking the SSLSocket.do_handshake() method. Calling SSLSocket.do_handshake() explicitly gives the program control over the blocking behavior of the socket I/O involved in the handshake. The parameter suppress_ragged_eofs specifies how the SSLSocket.recv() method should signal unexpected EOF from the other end of the connection. If specified as True (the default), it returns a normal EOF (an empty bytes object) in response to unexpected EOF errors raised from the underlying socket; if False, it will raise the exceptions back to the caller. session, see session. Changed in version 3.5: Always allow a server_hostname to be passed, even if OpenSSL does not have SNI. Changed in version 3.6: session argument was added. Changed in version 3.7: The method returns on instance of SSLContext.sslsocket_class instead of hard-coded SSLSocket.
SSLContext.sslsocket_class
The return type of SSLContext.wrap_socket(), defaults to SSLSocket. The attribute can be overridden on instance of class in order to return a custom subclass of SSLSocket. New in version 3.7.
SSLContext.wrap_bio(incoming, outgoing, server_side=False, server_hostname=None, session=None)
Wrap the BIO objects incoming and outgoing and return an instance of SSLContext.sslobject_class (default SSLObject). The SSL routines will read input data from the incoming BIO and write data to the outgoing BIO. The server_side, server_hostname and session parameters have the same meaning as in SSLContext.wrap_socket(). Changed in version 3.6: session argument was added. Changed in version 3.7: The method returns on instance of SSLContext.sslobject_class instead of hard-coded SSLObject.
SSLContext.sslobject_class
The return type of SSLContext.wrap_bio(), defaults to SSLObject. The attribute can be overridden on instance of class in order to return a custom subclass of SSLObject. New in version 3.7.
SSLContext.session_stats()
Get statistics about the SSL sessions created or managed by this context. A dictionary is returned which maps the names of each piece of information to their numeric values. For example, here is the total number of hits and misses in the session cache since the context was created: >>> stats = context.session_stats()
>>> stats['hits'], stats['misses']
(0, 0)
SSLContext.check_hostname
Whether to match the peer cert’s hostname in SSLSocket.do_handshake(). The context’s verify_mode must be set to CERT_OPTIONAL or CERT_REQUIRED, and you must pass server_hostname to wrap_socket() in order to match the hostname. Enabling hostname checking automatically sets verify_mode from CERT_NONE to CERT_REQUIRED. It cannot be set back to CERT_NONE as long as hostname checking is enabled. The PROTOCOL_TLS_CLIENT protocol enables hostname checking by default. With other protocols, hostname checking must be enabled explicitly. Example: import socket, ssl
context = ssl.SSLContext(ssl.PROTOCOL_TLSv1_2)
context.verify_mode = ssl.CERT_REQUIRED
context.check_hostname = True
context.load_default_certs()
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ssl_sock = context.wrap_socket(s, server_hostname='www.verisign.com')
ssl_sock.connect(('www.verisign.com', 443))
New in version 3.4. Changed in version 3.7: verify_mode is now automatically changed to CERT_REQUIRED when hostname checking is enabled and verify_mode is CERT_NONE. Previously the same operation would have failed with a ValueError. Note This features requires OpenSSL 0.9.8f or newer.
SSLContext.keylog_filename
Write TLS keys to a keylog file, whenever key material is generated or received. The keylog file is designed for debugging purposes only. The file format is specified by NSS and used by many traffic analyzers such as Wireshark. The log file is opened in append-only mode. Writes are synchronized between threads, but not between processes. New in version 3.8. Note This features requires OpenSSL 1.1.1 or newer.
SSLContext.maximum_version
A TLSVersion enum member representing the highest supported TLS version. The value defaults to TLSVersion.MAXIMUM_SUPPORTED. The attribute is read-only for protocols other than PROTOCOL_TLS, PROTOCOL_TLS_CLIENT, and PROTOCOL_TLS_SERVER. The attributes maximum_version, minimum_version and SSLContext.options all affect the supported SSL and TLS versions of the context. The implementation does not prevent invalid combination. For example a context with OP_NO_TLSv1_2 in options and maximum_version set to TLSVersion.TLSv1_2 will not be able to establish a TLS 1.2 connection. Note This attribute is not available unless the ssl module is compiled with OpenSSL 1.1.0g or newer. New in version 3.7.
SSLContext.minimum_version
Like SSLContext.maximum_version except it is the lowest supported version or TLSVersion.MINIMUM_SUPPORTED. Note This attribute is not available unless the ssl module is compiled with OpenSSL 1.1.0g or newer. New in version 3.7.
SSLContext.num_tickets
Control the number of TLS 1.3 session tickets of a TLS_PROTOCOL_SERVER context. The setting has no impact on TLS 1.0 to 1.2 connections. Note This attribute is not available unless the ssl module is compiled with OpenSSL 1.1.1 or newer. New in version 3.8.
SSLContext.options
An integer representing the set of SSL options enabled on this context. The default value is OP_ALL, but you can specify other options such as OP_NO_SSLv2 by ORing them together. Note With versions of OpenSSL older than 0.9.8m, it is only possible to set options, not to clear them. Attempting to clear an option (by resetting the corresponding bits) will raise a ValueError. Changed in version 3.6: SSLContext.options returns Options flags: >>> ssl.create_default_context().options
<Options.OP_ALL|OP_NO_SSLv3|OP_NO_SSLv2|OP_NO_COMPRESSION: 2197947391>
SSLContext.post_handshake_auth
Enable TLS 1.3 post-handshake client authentication. Post-handshake auth is disabled by default and a server can only request a TLS client certificate during the initial handshake. When enabled, a server may request a TLS client certificate at any time after the handshake. When enabled on client-side sockets, the client signals the server that it supports post-handshake authentication. When enabled on server-side sockets, SSLContext.verify_mode must be set to CERT_OPTIONAL or CERT_REQUIRED, too. The actual client cert exchange is delayed until SSLSocket.verify_client_post_handshake() is called and some I/O is performed. Note Only available with OpenSSL 1.1.1 and TLS 1.3 enabled. Without TLS 1.3 support, the property value is None and can’t be modified New in version 3.8.
SSLContext.protocol
The protocol version chosen when constructing the context. This attribute is read-only.
SSLContext.hostname_checks_common_name
Whether check_hostname falls back to verify the cert’s subject common name in the absence of a subject alternative name extension (default: true). Note Only writeable with OpenSSL 1.1.0 or higher. New in version 3.7. Changed in version 3.9.3: The flag had no effect with OpenSSL before version 1.1.1k. Python 3.8.9, 3.9.3, and 3.10 include workarounds for previous versions.
SSLContext.verify_flags
The flags for certificate verification operations. You can set flags like VERIFY_CRL_CHECK_LEAF by ORing them together. By default OpenSSL does neither require nor verify certificate revocation lists (CRLs). Available only with openssl version 0.9.8+. New in version 3.4. Changed in version 3.6: SSLContext.verify_flags returns VerifyFlags flags: >>> ssl.create_default_context().verify_flags
<VerifyFlags.VERIFY_X509_TRUSTED_FIRST: 32768>
SSLContext.verify_mode
Whether to try to verify other peers’ certificates and how to behave if verification fails. This attribute must be one of CERT_NONE, CERT_OPTIONAL or CERT_REQUIRED. Changed in version 3.6: SSLContext.verify_mode returns VerifyMode enum: >>> ssl.create_default_context().verify_mode
<VerifyMode.CERT_REQUIRED: 2>
Certificates Certificates in general are part of a public-key / private-key system. In this system, each principal, (which may be a machine, or a person, or an organization) is assigned a unique two-part encryption key. One part of the key is public, and is called the public key; the other part is kept secret, and is called the private key. The two parts are related, in that if you encrypt a message with one of the parts, you can decrypt it with the other part, and only with the other part. A certificate contains information about two principals. It contains the name of a subject, and the subject’s public key. It also contains a statement by a second principal, the issuer, that the subject is who they claim to be, and that this is indeed the subject’s public key. The issuer’s statement is signed with the issuer’s private key, which only the issuer knows. However, anyone can verify the issuer’s statement by finding the issuer’s public key, decrypting the statement with it, and comparing it to the other information in the certificate. The certificate also contains information about the time period over which it is valid. This is expressed as two fields, called “notBefore” and “notAfter”. In the Python use of certificates, a client or server can use a certificate to prove who they are. The other side of a network connection can also be required to produce a certificate, and that certificate can be validated to the satisfaction of the client or server that requires such validation. The connection attempt can be set to raise an exception if the validation fails. Validation is done automatically, by the underlying OpenSSL framework; the application need not concern itself with its mechanics. But the application does usually need to provide sets of certificates to allow this process to take place. Python uses files to contain certificates. They should be formatted as “PEM” (see RFC 1422), which is a base-64 encoded form wrapped with a header line and a footer line: -----BEGIN CERTIFICATE-----
... (certificate in base64 PEM encoding) ...
-----END CERTIFICATE-----
Certificate chains The Python files which contain certificates can contain a sequence of certificates, sometimes called a certificate chain. This chain should start with the specific certificate for the principal who “is” the client or server, and then the certificate for the issuer of that certificate, and then the certificate for the issuer of that certificate, and so on up the chain till you get to a certificate which is self-signed, that is, a certificate which has the same subject and issuer, sometimes called a root certificate. The certificates should just be concatenated together in the certificate file. For example, suppose we had a three certificate chain, from our server certificate to the certificate of the certification authority that signed our server certificate, to the root certificate of the agency which issued the certification authority’s certificate: -----BEGIN CERTIFICATE-----
... (certificate for your server)...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
... (the certificate for the CA)...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
... (the root certificate for the CA's issuer)...
-----END CERTIFICATE-----
CA certificates If you are going to require validation of the other side of the connection’s certificate, you need to provide a “CA certs” file, filled with the certificate chains for each issuer you are willing to trust. Again, this file just contains these chains concatenated together. For validation, Python will use the first chain it finds in the file which matches. The platform’s certificates file can be used by calling SSLContext.load_default_certs(), this is done automatically with create_default_context(). Combined key and certificate Often the private key is stored in the same file as the certificate; in this case, only the certfile parameter to SSLContext.load_cert_chain() and wrap_socket() needs to be passed. If the private key is stored with the certificate, it should come before the first certificate in the certificate chain: -----BEGIN RSA PRIVATE KEY-----
... (private key in base64 encoding) ...
-----END RSA PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
... (certificate in base64 PEM encoding) ...
-----END CERTIFICATE-----
Self-signed certificates If you are going to create a server that provides SSL-encrypted connection services, you will need to acquire a certificate for that service. There are many ways of acquiring appropriate certificates, such as buying one from a certification authority. Another common practice is to generate a self-signed certificate. The simplest way to do this is with the OpenSSL package, using something like the following: % openssl req -new -x509 -days 365 -nodes -out cert.pem -keyout cert.pem
Generating a 1024 bit RSA private key
.......++++++
.............................++++++
writing new private key to 'cert.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:MyState
Locality Name (eg, city) []:Some City
Organization Name (eg, company) [Internet Widgits Pty Ltd]:My Organization, Inc.
Organizational Unit Name (eg, section) []:My Group
Common Name (eg, YOUR name) []:myserver.mygroup.myorganization.com
Email Address []:ops@myserver.mygroup.myorganization.com
%
The disadvantage of a self-signed certificate is that it is its own root certificate, and no one else will have it in their cache of known (and trusted) root certificates. Examples Testing for SSL support To test for the presence of SSL support in a Python installation, user code should use the following idiom: try:
import ssl
except ImportError:
pass
else:
... # do something that requires SSL support
Client-side operation This example creates a SSL context with the recommended security settings for client sockets, including automatic certificate verification: >>> context = ssl.create_default_context()
If you prefer to tune security settings yourself, you might create a context from scratch (but beware that you might not get the settings right): >>> context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
>>> context.load_verify_locations("/etc/ssl/certs/ca-bundle.crt")
(this snippet assumes your operating system places a bundle of all CA certificates in /etc/ssl/certs/ca-bundle.crt; if not, you’ll get an error and have to adjust the location) The PROTOCOL_TLS_CLIENT protocol configures the context for cert validation and hostname verification. verify_mode is set to CERT_REQUIRED and check_hostname is set to True. All other protocols create SSL contexts with insecure defaults. When you use the context to connect to a server, CERT_REQUIRED and check_hostname validate the server certificate: it ensures that the server certificate was signed with one of the CA certificates, checks the signature for correctness, and verifies other properties like validity and identity of the hostname: >>> conn = context.wrap_socket(socket.socket(socket.AF_INET),
... server_hostname="www.python.org")
>>> conn.connect(("www.python.org", 443))
You may then fetch the certificate: >>> cert = conn.getpeercert()
Visual inspection shows that the certificate does identify the desired service (that is, the HTTPS host www.python.org): >>> pprint.pprint(cert)
{'OCSP': ('http://ocsp.digicert.com',),
'caIssuers': ('http://cacerts.digicert.com/DigiCertSHA2ExtendedValidationServerCA.crt',),
'crlDistributionPoints': ('http://crl3.digicert.com/sha2-ev-server-g1.crl',
'http://crl4.digicert.com/sha2-ev-server-g1.crl'),
'issuer': ((('countryName', 'US'),),
(('organizationName', 'DigiCert Inc'),),
(('organizationalUnitName', 'www.digicert.com'),),
(('commonName', 'DigiCert SHA2 Extended Validation Server CA'),)),
'notAfter': 'Sep 9 12:00:00 2016 GMT',
'notBefore': 'Sep 5 00:00:00 2014 GMT',
'serialNumber': '01BB6F00122B177F36CAB49CEA8B6B26',
'subject': ((('businessCategory', 'Private Organization'),),
(('1.3.6.1.4.1.311.60.2.1.3', 'US'),),
(('1.3.6.1.4.1.311.60.2.1.2', 'Delaware'),),
(('serialNumber', '3359300'),),
(('streetAddress', '16 Allen Rd'),),
(('postalCode', '03894-4801'),),
(('countryName', 'US'),),
(('stateOrProvinceName', 'NH'),),
(('localityName', 'Wolfeboro'),),
(('organizationName', 'Python Software Foundation'),),
(('commonName', 'www.python.org'),)),
'subjectAltName': (('DNS', 'www.python.org'),
('DNS', 'python.org'),
('DNS', 'pypi.org'),
('DNS', 'docs.python.org'),
('DNS', 'testpypi.org'),
('DNS', 'bugs.python.org'),
('DNS', 'wiki.python.org'),
('DNS', 'hg.python.org'),
('DNS', 'mail.python.org'),
('DNS', 'packaging.python.org'),
('DNS', 'pythonhosted.org'),
('DNS', 'www.pythonhosted.org'),
('DNS', 'test.pythonhosted.org'),
('DNS', 'us.pycon.org'),
('DNS', 'id.python.org')),
'version': 3}
Now the SSL channel is established and the certificate verified, you can proceed to talk with the server: >>> conn.sendall(b"HEAD / HTTP/1.0\r\nHost: linuxfr.org\r\n\r\n")
>>> pprint.pprint(conn.recv(1024).split(b"\r\n"))
[b'HTTP/1.1 200 OK',
b'Date: Sat, 18 Oct 2014 18:27:20 GMT',
b'Server: nginx',
b'Content-Type: text/html; charset=utf-8',
b'X-Frame-Options: SAMEORIGIN',
b'Content-Length: 45679',
b'Accept-Ranges: bytes',
b'Via: 1.1 varnish',
b'Age: 2188',
b'X-Served-By: cache-lcy1134-LCY',
b'X-Cache: HIT',
b'X-Cache-Hits: 11',
b'Vary: Cookie',
b'Strict-Transport-Security: max-age=63072000; includeSubDomains',
b'Connection: close',
b'',
b'']
See the discussion of Security considerations below. Server-side operation For server operation, typically you’ll need to have a server certificate, and private key, each in a file. You’ll first create a context holding the key and the certificate, so that clients can check your authenticity. Then you’ll open a socket, bind it to a port, call listen() on it, and start waiting for clients to connect: import socket, ssl
context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
context.load_cert_chain(certfile="mycertfile", keyfile="mykeyfile")
bindsocket = socket.socket()
bindsocket.bind(('myaddr.mydomain.com', 10023))
bindsocket.listen(5)
When a client connects, you’ll call accept() on the socket to get the new socket from the other end, and use the context’s SSLContext.wrap_socket() method to create a server-side SSL socket for the connection: while True:
newsocket, fromaddr = bindsocket.accept()
connstream = context.wrap_socket(newsocket, server_side=True)
try:
deal_with_client(connstream)
finally:
connstream.shutdown(socket.SHUT_RDWR)
connstream.close()
Then you’ll read data from the connstream and do something with it till you are finished with the client (or the client is finished with you): def deal_with_client(connstream):
data = connstream.recv(1024)
# empty data means the client is finished with us
while data:
if not do_something(connstream, data):
# we'll assume do_something returns False
# when we're finished with client
break
data = connstream.recv(1024)
# finished with client
And go back to listening for new client connections (of course, a real server would probably handle each client connection in a separate thread, or put the sockets in non-blocking mode and use an event loop). Notes on non-blocking sockets SSL sockets behave slightly different than regular sockets in non-blocking mode. When working with non-blocking sockets, there are thus several things you need to be aware of:
Most SSLSocket methods will raise either SSLWantWriteError or SSLWantReadError instead of BlockingIOError if an I/O operation would block. SSLWantReadError will be raised if a read operation on the underlying socket is necessary, and SSLWantWriteError for a write operation on the underlying socket. Note that attempts to write to an SSL socket may require reading from the underlying socket first, and attempts to read from the SSL socket may require a prior write to the underlying socket. Changed in version 3.5: In earlier Python versions, the SSLSocket.send() method returned zero instead of raising SSLWantWriteError or SSLWantReadError. Calling select() tells you that the OS-level socket can be read from (or written to), but it does not imply that there is sufficient data at the upper SSL layer. For example, only part of an SSL frame might have arrived. Therefore, you must be ready to handle SSLSocket.recv() and SSLSocket.send() failures, and retry after another call to select().
Conversely, since the SSL layer has its own framing, a SSL socket may still have data available for reading without select() being aware of it. Therefore, you should first call SSLSocket.recv() to drain any potentially available data, and then only block on a select() call if still necessary. (of course, similar provisions apply when using other primitives such as poll(), or those in the selectors module)
The SSL handshake itself will be non-blocking: the SSLSocket.do_handshake() method has to be retried until it returns successfully. Here is a synopsis using select() to wait for the socket’s readiness: while True:
try:
sock.do_handshake()
break
except ssl.SSLWantReadError:
select.select([sock], [], [])
except ssl.SSLWantWriteError:
select.select([], [sock], [])
See also The asyncio module supports non-blocking SSL sockets and provides a higher level API. It polls for events using the selectors module and handles SSLWantWriteError, SSLWantReadError and BlockingIOError exceptions. It runs the SSL handshake asynchronously as well. Memory BIO Support New in version 3.5. Ever since the SSL module was introduced in Python 2.6, the SSLSocket class has provided two related but distinct areas of functionality: SSL protocol handling Network IO The network IO API is identical to that provided by socket.socket, from which SSLSocket also inherits. This allows an SSL socket to be used as a drop-in replacement for a regular socket, making it very easy to add SSL support to an existing application. Combining SSL protocol handling and network IO usually works well, but there are some cases where it doesn’t. An example is async IO frameworks that want to use a different IO multiplexing model than the “select/poll on a file descriptor” (readiness based) model that is assumed by socket.socket and by the internal OpenSSL socket IO routines. This is mostly relevant for platforms like Windows where this model is not efficient. For this purpose, a reduced scope variant of SSLSocket called SSLObject is provided.
class ssl.SSLObject
A reduced-scope variant of SSLSocket representing an SSL protocol instance that does not contain any network IO methods. This class is typically used by framework authors that want to implement asynchronous IO for SSL through memory buffers. This class implements an interface on top of a low-level SSL object as implemented by OpenSSL. This object captures the state of an SSL connection but does not provide any network IO itself. IO needs to be performed through separate “BIO” objects which are OpenSSL’s IO abstraction layer. This class has no public constructor. An SSLObject instance must be created using the wrap_bio() method. This method will create the SSLObject instance and bind it to a pair of BIOs. The incoming BIO is used to pass data from Python to the SSL protocol instance, while the outgoing BIO is used to pass data the other way around. The following methods are available: context server_side server_hostname session session_reused read() write() getpeercert() selected_alpn_protocol() selected_npn_protocol() cipher() shared_ciphers() compression() pending() do_handshake() verify_client_post_handshake() unwrap() get_channel_binding() version() When compared to SSLSocket, this object lacks the following features: Any form of network IO; recv() and send() read and write only to the underlying MemoryBIO buffers. There is no do_handshake_on_connect machinery. You must always manually call do_handshake() to start the handshake. There is no handling of suppress_ragged_eofs. All end-of-file conditions that are in violation of the protocol are reported via the SSLEOFError exception. The method unwrap() call does not return anything, unlike for an SSL socket where it returns the underlying socket. The server_name_callback callback passed to SSLContext.set_servername_callback() will get an SSLObject instance instead of a SSLSocket instance as its first parameter. Some notes related to the use of SSLObject: All IO on an SSLObject is non-blocking. This means that for example read() will raise an SSLWantReadError if it needs more data than the incoming BIO has available. There is no module-level wrap_bio() call like there is for wrap_socket(). An SSLObject is always created via an SSLContext. Changed in version 3.7: SSLObject instances must to created with wrap_bio(). In earlier versions, it was possible to create instances directly. This was never documented or officially supported.
An SSLObject communicates with the outside world using memory buffers. The class MemoryBIO provides a memory buffer that can be used for this purpose. It wraps an OpenSSL memory BIO (Basic IO) object:
class ssl.MemoryBIO
A memory buffer that can be used to pass data between Python and an SSL protocol instance.
pending
Return the number of bytes currently in the memory buffer.
eof
A boolean indicating whether the memory BIO is current at the end-of-file position.
read(n=-1)
Read up to n bytes from the memory buffer. If n is not specified or negative, all bytes are returned.
write(buf)
Write the bytes from buf to the memory BIO. The buf argument must be an object supporting the buffer protocol. The return value is the number of bytes written, which is always equal to the length of buf.
write_eof()
Write an EOF marker to the memory BIO. After this method has been called, it is illegal to call write(). The attribute eof will become true after all data currently in the buffer has been read.
SSL session New in version 3.6.
class ssl.SSLSession
Session object used by session.
id
time
timeout
ticket_lifetime_hint
has_ticket
Security considerations Best defaults For client use, if you don’t have any special requirements for your security policy, it is highly recommended that you use the create_default_context() function to create your SSL context. It will load the system’s trusted CA certificates, enable certificate validation and hostname checking, and try to choose reasonably secure protocol and cipher settings. For example, here is how you would use the smtplib.SMTP class to create a trusted, secure connection to a SMTP server: >>> import ssl, smtplib
>>> smtp = smtplib.SMTP("mail.python.org", port=587)
>>> context = ssl.create_default_context()
>>> smtp.starttls(context=context)
(220, b'2.0.0 Ready to start TLS')
If a client certificate is needed for the connection, it can be added with SSLContext.load_cert_chain(). By contrast, if you create the SSL context by calling the SSLContext constructor yourself, it will not have certificate validation nor hostname checking enabled by default. If you do so, please read the paragraphs below to achieve a good security level. Manual settings Verifying certificates When calling the SSLContext constructor directly, CERT_NONE is the default. Since it does not authenticate the other peer, it can be insecure, especially in client mode where most of time you would like to ensure the authenticity of the server you’re talking to. Therefore, when in client mode, it is highly recommended to use CERT_REQUIRED. However, it is in itself not sufficient; you also have to check that the server certificate, which can be obtained by calling SSLSocket.getpeercert(), matches the desired service. For many protocols and applications, the service can be identified by the hostname; in this case, the match_hostname() function can be used. This common check is automatically performed when SSLContext.check_hostname is enabled. Changed in version 3.7: Hostname matchings is now performed by OpenSSL. Python no longer uses match_hostname(). In server mode, if you want to authenticate your clients using the SSL layer (rather than using a higher-level authentication mechanism), you’ll also have to specify CERT_REQUIRED and similarly check the client certificate. Protocol versions SSL versions 2 and 3 are considered insecure and are therefore dangerous to use. If you want maximum compatibility between clients and servers, it is recommended to use PROTOCOL_TLS_CLIENT or PROTOCOL_TLS_SERVER as the protocol version. SSLv2 and SSLv3 are disabled by default. >>> client_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
>>> client_context.options |= ssl.OP_NO_TLSv1
>>> client_context.options |= ssl.OP_NO_TLSv1_1
The SSL context created above will only allow TLSv1.2 and later (if supported by your system) connections to a server. PROTOCOL_TLS_CLIENT implies certificate validation and hostname checks by default. You have to load certificates into the context. Cipher selection If you have advanced security requirements, fine-tuning of the ciphers enabled when negotiating a SSL session is possible through the SSLContext.set_ciphers() method. Starting from Python 3.2.3, the ssl module disables certain weak ciphers by default, but you may want to further restrict the cipher choice. Be sure to read OpenSSL’s documentation about the cipher list format. If you want to check which ciphers are enabled by a given cipher list, use SSLContext.get_ciphers() or the openssl ciphers command on your system. Multi-processing If using this module as part of a multi-processed application (using, for example the multiprocessing or concurrent.futures modules), be aware that OpenSSL’s internal random number generator does not properly handle forked processes. Applications must change the PRNG state of the parent process if they use any SSL feature with os.fork(). Any successful call of RAND_add(), RAND_bytes() or RAND_pseudo_bytes() is sufficient. TLS 1.3 New in version 3.7. Python has provisional and experimental support for TLS 1.3 with OpenSSL 1.1.1. The new protocol behaves slightly differently than previous version of TLS/SSL. Some new TLS 1.3 features are not yet available. TLS 1.3 uses a disjunct set of cipher suites. All AES-GCM and ChaCha20 cipher suites are enabled by default. The method SSLContext.set_ciphers() cannot enable or disable any TLS 1.3 ciphers yet, but SSLContext.get_ciphers() returns them. Session tickets are no longer sent as part of the initial handshake and are handled differently. SSLSocket.session and SSLSession are not compatible with TLS 1.3. Client-side certificates are also no longer verified during the initial handshake. A server can request a certificate at any time. Clients process certificate requests while they send or receive application data from the server. TLS 1.3 features like early data, deferred TLS client cert request, signature algorithm configuration, and rekeying are not supported yet. LibreSSL support LibreSSL is a fork of OpenSSL 1.0.1. The ssl module has limited support for LibreSSL. Some features are not available when the ssl module is compiled with LibreSSL. LibreSSL >= 2.6.1 no longer supports NPN. The methods SSLContext.set_npn_protocols() and SSLSocket.selected_npn_protocol() are not available.
SSLContext.set_default_verify_paths() ignores the env vars SSL_CERT_FILE and SSL_CERT_PATH although get_default_verify_paths() still reports them. See also
Class socket.socket
Documentation of underlying socket class SSL/TLS Strong Encryption: An Introduction
Intro from the Apache HTTP Server documentation RFC 1422: Privacy Enhancement for Internet Electronic Mail: Part II: Certificate-Based Key Management
Steve Kent RFC 4086: Randomness Requirements for Security
Donald E., Jeffrey I. Schiller RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile
D. Cooper RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2
T. Dierks et. al. RFC 6066: Transport Layer Security (TLS) Extensions
D. Eastlake IANA TLS: Transport Layer Security (TLS) Parameters
IANA RFC 7525: Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)
IETF Mozilla’s Server Side TLS recommendations
Mozilla | python.library.ssl |
class ssl.AlertDescription
enum.IntEnum collection of ALERT_DESCRIPTION_* constants. New in version 3.6. | python.library.ssl#ssl.AlertDescription |
ssl.ALERT_DESCRIPTION_HANDSHAKE_FAILURE
ssl.ALERT_DESCRIPTION_INTERNAL_ERROR
ALERT_DESCRIPTION_*
Alert Descriptions from RFC 5246 and others. The IANA TLS Alert Registry contains this list and references to the RFCs where their meaning is defined. Used as the return value of the callback function in SSLContext.set_servername_callback(). New in version 3.4. | python.library.ssl#ssl.ALERT_DESCRIPTION_HANDSHAKE_FAILURE |
ssl.ALERT_DESCRIPTION_HANDSHAKE_FAILURE
ssl.ALERT_DESCRIPTION_INTERNAL_ERROR
ALERT_DESCRIPTION_*
Alert Descriptions from RFC 5246 and others. The IANA TLS Alert Registry contains this list and references to the RFCs where their meaning is defined. Used as the return value of the callback function in SSLContext.set_servername_callback(). New in version 3.4. | python.library.ssl#ssl.ALERT_DESCRIPTION_INTERNAL_ERROR |
exception ssl.CertificateError
An alias for SSLCertVerificationError. Changed in version 3.7: The exception is now an alias for SSLCertVerificationError. | python.library.ssl#ssl.CertificateError |
ssl.CERT_NONE
Possible value for SSLContext.verify_mode, or the cert_reqs parameter to wrap_socket(). Except for PROTOCOL_TLS_CLIENT, it is the default mode. With client-side sockets, just about any cert is accepted. Validation errors, such as untrusted or expired cert, are ignored and do not abort the TLS/SSL handshake. In server mode, no certificate is requested from the client, so the client does not send any for client cert authentication. See the discussion of Security considerations below. | python.library.ssl#ssl.CERT_NONE |
ssl.CERT_OPTIONAL
Possible value for SSLContext.verify_mode, or the cert_reqs parameter to wrap_socket(). In client mode, CERT_OPTIONAL has the same meaning as CERT_REQUIRED. It is recommended to use CERT_REQUIRED for client-side sockets instead. In server mode, a client certificate request is sent to the client. The client may either ignore the request or send a certificate in order perform TLS client cert authentication. If the client chooses to send a certificate, it is verified. Any verification error immediately aborts the TLS handshake. Use of this setting requires a valid set of CA certificates to be passed, either to SSLContext.load_verify_locations() or as a value of the ca_certs parameter to wrap_socket(). | python.library.ssl#ssl.CERT_OPTIONAL |
ssl.CERT_REQUIRED
Possible value for SSLContext.verify_mode, or the cert_reqs parameter to wrap_socket(). In this mode, certificates are required from the other side of the socket connection; an SSLError will be raised if no certificate is provided, or if its validation fails. This mode is not sufficient to verify a certificate in client mode as it does not match hostnames. check_hostname must be enabled as well to verify the authenticity of a cert. PROTOCOL_TLS_CLIENT uses CERT_REQUIRED and enables check_hostname by default. With server socket, this mode provides mandatory TLS client cert authentication. A client certificate request is sent to the client and the client must provide a valid and trusted certificate. Use of this setting requires a valid set of CA certificates to be passed, either to SSLContext.load_verify_locations() or as a value of the ca_certs parameter to wrap_socket(). | python.library.ssl#ssl.CERT_REQUIRED |
ssl.cert_time_to_seconds(cert_time)
Return the time in seconds since the Epoch, given the cert_time string representing the “notBefore” or “notAfter” date from a certificate in "%b %d %H:%M:%S %Y %Z" strptime format (C locale). Here’s an example: >>> import ssl
>>> timestamp = ssl.cert_time_to_seconds("Jan 5 09:34:43 2018 GMT")
>>> timestamp
1515144883
>>> from datetime import datetime
>>> print(datetime.utcfromtimestamp(timestamp))
2018-01-05 09:34:43
“notBefore” or “notAfter” dates must use GMT (RFC 5280). Changed in version 3.5: Interpret the input time as a time in UTC as specified by ‘GMT’ timezone in the input string. Local timezone was used previously. Return an integer (no fractions of a second in the input format) | python.library.ssl#ssl.cert_time_to_seconds |
ssl.CHANNEL_BINDING_TYPES
List of supported TLS channel binding types. Strings in this list can be used as arguments to SSLSocket.get_channel_binding(). New in version 3.3. | python.library.ssl#ssl.CHANNEL_BINDING_TYPES |
ssl.create_default_context(purpose=Purpose.SERVER_AUTH, cafile=None, capath=None, cadata=None)
Return a new SSLContext object with default settings for the given purpose. The settings are chosen by the ssl module, and usually represent a higher security level than when calling the SSLContext constructor directly. cafile, capath, cadata represent optional CA certificates to trust for certificate verification, as in SSLContext.load_verify_locations(). If all three are None, this function can choose to trust the system’s default CA certificates instead. The settings are: PROTOCOL_TLS, OP_NO_SSLv2, and OP_NO_SSLv3 with high encryption cipher suites without RC4 and without unauthenticated cipher suites. Passing SERVER_AUTH as purpose sets verify_mode to CERT_REQUIRED and either loads CA certificates (when at least one of cafile, capath or cadata is given) or uses SSLContext.load_default_certs() to load default CA certificates. When keylog_filename is supported and the environment variable SSLKEYLOGFILE is set, create_default_context() enables key logging. Note The protocol, options, cipher and other settings may change to more restrictive values anytime without prior deprecation. The values represent a fair balance between compatibility and security. If your application needs specific settings, you should create a SSLContext and apply the settings yourself. Note If you find that when certain older clients or servers attempt to connect with a SSLContext created by this function that they get an error stating “Protocol or cipher suite mismatch”, it may be that they only support SSL3.0 which this function excludes using the OP_NO_SSLv3. SSL3.0 is widely considered to be completely broken. If you still wish to continue to use this function but still allow SSL 3.0 connections you can re-enable them using: ctx = ssl.create_default_context(Purpose.CLIENT_AUTH)
ctx.options &= ~ssl.OP_NO_SSLv3
New in version 3.4. Changed in version 3.4.4: RC4 was dropped from the default cipher string. Changed in version 3.6: ChaCha20/Poly1305 was added to the default cipher string. 3DES was dropped from the default cipher string. Changed in version 3.8: Support for key logging to SSLKEYLOGFILE was added. | python.library.ssl#ssl.create_default_context |
ssl.DER_cert_to_PEM_cert(DER_cert_bytes)
Given a certificate as a DER-encoded blob of bytes, returns a PEM-encoded string version of the same certificate. | python.library.ssl#ssl.DER_cert_to_PEM_cert |
ssl.enum_certificates(store_name)
Retrieve certificates from Windows’ system cert store. store_name may be one of CA, ROOT or MY. Windows may provide additional cert stores, too. The function returns a list of (cert_bytes, encoding_type, trust) tuples. The encoding_type specifies the encoding of cert_bytes. It is either x509_asn for X.509 ASN.1 data or pkcs_7_asn for PKCS#7 ASN.1 data. Trust specifies the purpose of the certificate as a set of OIDS or exactly True if the certificate is trustworthy for all purposes. Example: >>> ssl.enum_certificates("CA")
[(b'data...', 'x509_asn', {'1.3.6.1.5.5.7.3.1', '1.3.6.1.5.5.7.3.2'}),
(b'data...', 'x509_asn', True)]
Availability: Windows. New in version 3.4. | python.library.ssl#ssl.enum_certificates |
ssl.enum_crls(store_name)
Retrieve CRLs from Windows’ system cert store. store_name may be one of CA, ROOT or MY. Windows may provide additional cert stores, too. The function returns a list of (cert_bytes, encoding_type, trust) tuples. The encoding_type specifies the encoding of cert_bytes. It is either x509_asn for X.509 ASN.1 data or pkcs_7_asn for PKCS#7 ASN.1 data. Availability: Windows. New in version 3.4. | python.library.ssl#ssl.enum_crls |
ssl.get_default_verify_paths()
Returns a named tuple with paths to OpenSSL’s default cafile and capath. The paths are the same as used by SSLContext.set_default_verify_paths(). The return value is a named tuple DefaultVerifyPaths:
cafile - resolved path to cafile or None if the file doesn’t exist,
capath - resolved path to capath or None if the directory doesn’t exist,
openssl_cafile_env - OpenSSL’s environment key that points to a cafile,
openssl_cafile - hard coded path to a cafile,
openssl_capath_env - OpenSSL’s environment key that points to a capath,
openssl_capath - hard coded path to a capath directory Availability: LibreSSL ignores the environment vars openssl_cafile_env and openssl_capath_env. New in version 3.4. | python.library.ssl#ssl.get_default_verify_paths |
ssl.get_server_certificate(addr, ssl_version=PROTOCOL_TLS, ca_certs=None)
Given the address addr of an SSL-protected server, as a (hostname, port-number) pair, fetches the server’s certificate, and returns it as a PEM-encoded string. If ssl_version is specified, uses that version of the SSL protocol to attempt to connect to the server. If ca_certs is specified, it should be a file containing a list of root certificates, the same format as used for the same parameter in SSLContext.wrap_socket(). The call will attempt to validate the server certificate against that set of root certificates, and will fail if the validation attempt fails. Changed in version 3.3: This function is now IPv6-compatible. Changed in version 3.5: The default ssl_version is changed from PROTOCOL_SSLv3 to PROTOCOL_TLS for maximum compatibility with modern servers. | python.library.ssl#ssl.get_server_certificate |
ssl.HAS_ALPN
Whether the OpenSSL library has built-in support for the Application-Layer Protocol Negotiation TLS extension as described in RFC 7301. New in version 3.5. | python.library.ssl#ssl.HAS_ALPN |
ssl.HAS_ECDH
Whether the OpenSSL library has built-in support for the Elliptic Curve-based Diffie-Hellman key exchange. This should be true unless the feature was explicitly disabled by the distributor. New in version 3.3. | python.library.ssl#ssl.HAS_ECDH |
ssl.HAS_NEVER_CHECK_COMMON_NAME
Whether the OpenSSL library has built-in support not checking subject common name and SSLContext.hostname_checks_common_name is writeable. New in version 3.7. | python.library.ssl#ssl.HAS_NEVER_CHECK_COMMON_NAME |
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