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# Licensed under the MIT License. See LICENSE in the project root
# for license information.
import socket
import sys
import threading
from debugpy.common import log
from debugpy.common.util import hide_thread_from_debugger
def can_bind_ipv4_localhost():
"""Check if we can bind to IPv4 localhost."""
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# Try to bind to IPv4 localhost on port 0 (any available port)
sock.bind(("127.0.0.1", 0))
sock.close()
return True
except (socket.error, OSError, AttributeError):
return False
def can_bind_ipv6_localhost():
"""Check if we can bind to IPv6 localhost."""
try:
sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# Try to bind to IPv6 localhost on port 0 (any available port)
sock.bind(("::1", 0))
sock.close()
return True
except (socket.error, OSError, AttributeError):
return False
def get_default_localhost():
"""Get the default localhost address.
Defaults to IPv4 '127.0.0.1', but falls back to IPv6 '::1' if IPv4 is unavailable.
"""
# First try IPv4 (preferred default)
if can_bind_ipv4_localhost():
return "127.0.0.1"
# Fall back to IPv6 if IPv4 is not available
if can_bind_ipv6_localhost():
return "::1"
# If neither works, still return IPv4 as a last resort
# (this is a very unusual situation)
return "127.0.0.1"
def get_address(sock):
"""Gets the socket address host and port."""
try:
host, port = sock.getsockname()[:2]
except Exception as exc:
log.swallow_exception("Failed to get socket address:")
raise RuntimeError(f"Failed to get socket address: {exc}") from exc
return host, port
def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
"""Return a local server socket listening on the given port."""
assert backlog > 0
if host is None:
host = get_default_localhost()
if port is None:
port = 0
ipv6 = host.count(":") > 1
try:
server = _new_sock(ipv6)
if port != 0:
# If binding to a specific port, make sure that the user doesn't have
# to wait until the OS times out the socket to be able to use that port
# again.if the server or the adapter crash or are force-killed.
if sys.platform == "win32":
server.setsockopt(socket.SOL_SOCKET, socket.SO_EXCLUSIVEADDRUSE, 1)
else:
try:
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
except (AttributeError, OSError): # pragma: no cover
pass # Not available everywhere
server.bind((host, port))
if timeout is not None:
server.settimeout(timeout)
server.listen(backlog)
except Exception: # pragma: no cover
server.close()
raise
return server
def create_client(ipv6=False):
"""Return a client socket that may be connected to a remote address."""
return _new_sock(ipv6)
def _new_sock(ipv6=False):
address_family = socket.AF_INET6 if ipv6 else socket.AF_INET
sock = socket.socket(address_family, socket.SOCK_STREAM, socket.IPPROTO_TCP)
# Set TCP keepalive on an open socket.
# It activates after 1 second (TCP_KEEPIDLE,) of idleness,
# then sends a keepalive ping once every 3 seconds (TCP_KEEPINTVL),
# and closes the connection after 5 failed ping (TCP_KEEPCNT), or 15 seconds
try:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
except (AttributeError, OSError): # pragma: no cover
pass # May not be available everywhere.
try:
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 1)
except (AttributeError, OSError): # pragma: no cover
pass # May not be available everywhere.
try:
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 3)
except (AttributeError, OSError): # pragma: no cover
pass # May not be available everywhere.
try:
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 5)
except (AttributeError, OSError): # pragma: no cover
pass # May not be available everywhere.
return sock
def shut_down(sock, how=socket.SHUT_RDWR):
"""Shut down the given socket."""
sock.shutdown(how)
def close_socket(sock):
"""Shutdown and close the socket."""
try:
shut_down(sock)
except Exception: # pragma: no cover
pass
sock.close()
def serve(name, handler, host, port=0, backlog=socket.SOMAXCONN, timeout=None):
"""Accepts TCP connections on the specified host and port, and invokes the
provided handler function for every new connection.
Returns the created server socket.
"""
assert backlog > 0
try:
listener = create_server(host, port, backlog, timeout)
except Exception: # pragma: no cover
log.reraise_exception(
"Error listening for incoming {0} connections on {1}:{2}:", name, host, port
)
host, port = get_address(listener)
log.info("Listening for incoming {0} connections on {1}:{2}...", name, host, port)
def accept_worker():
while True:
try:
sock, address = listener.accept()
other_host, other_port = address[:2]
except (OSError, socket.error):
# Listener socket has been closed.
break
log.info(
"Accepted incoming {0} connection from {1}:{2}.",
name,
other_host,
other_port,
)
handler(sock)
thread = threading.Thread(target=accept_worker)
thread.daemon = True
hide_thread_from_debugger(thread)
thread.start()
return listener
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