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"""
File serving utilities for secure and efficient file delivery.
This module provides utilities for serving files with access control,
caching, range requests, and security checks.
"""
import os
import mimetypes
from pathlib import Path
from typing import Optional, Dict, Any, Tuple
from datetime import datetime, timedelta
import hashlib
from fastapi import Request, Response, HTTPException, status
from fastapi.responses import StreamingResponse, FileResponse
import aiofiles
from ..core.config import get_settings
from ..core.logger import get_logger
settings = get_settings()
logger = get_logger(__name__)
class FileServingManager:
"""Manager for secure file serving operations."""
def __init__(self):
self.cache_control_headers = {
'image': 'public, max-age=86400', # 1 day
'video': 'public, max-age=3600', # 1 hour
'audio': 'public, max-age=3600', # 1 hour
'document': 'private, max-age=300', # 5 minutes
'archive': 'private, max-age=300' # 5 minutes
}
async def serve_file(
self,
file_path: str,
file_type: str,
original_filename: str,
request: Request,
inline: bool = False,
enable_caching: bool = True,
user_id: Optional[str] = None
) -> StreamingResponse:
"""
Serve a file with proper headers and security checks.
Args:
file_path: Path to the file
file_type: Type of file (image, video, etc.)
original_filename: Original filename for Content-Disposition
request: FastAPI request object
inline: Whether to serve inline or as attachment
enable_caching: Whether to enable caching headers
Returns:
StreamingResponse with file content
Raises:
HTTPException: If file not found or access denied
"""
path = Path(file_path)
# Security check - ensure file is within allowed directories
if not self._is_safe_path(path):
logger.warning(
"Attempted access to unsafe file path",
file_path=file_path,
user_id=user_id,
resolved_path=str(path.resolve()) if path.exists() else "non-existent"
)
raise HTTPException(
status_code=status.HTTP_403_FORBIDDEN,
detail="Access denied: Invalid file path"
)
# Check if file exists
if not path.exists() or not path.is_file():
logger.info(
"File not found",
file_path=file_path,
user_id=user_id,
exists=path.exists(),
is_file=path.is_file() if path.exists() else False
)
raise HTTPException(
status_code=status.HTTP_404_NOT_FOUND,
detail="File not found"
)
# Get file stats
file_stat = path.stat()
file_size = file_stat.st_size
last_modified = datetime.fromtimestamp(file_stat.st_mtime)
# Generate ETag
etag = self._generate_etag(path, file_stat)
# Check conditional requests
if self._check_not_modified(request, etag, last_modified):
return Response(status_code=status.HTTP_304_NOT_MODIFIED)
# Determine content type
content_type = self._get_content_type(path, file_type)
# Check for range requests
range_header = request.headers.get('range')
if range_header:
return await self._serve_range_request(
path, file_size, range_header, content_type,
original_filename, inline, enable_caching, file_type,
etag, last_modified
)
# Serve full file
return await self._serve_full_file(
path, file_size, content_type, original_filename,
inline, enable_caching, file_type, etag, last_modified
)
def _is_safe_path(self, path: Path) -> bool:
"""Check if file path is safe and within allowed directories."""
try:
# Resolve path to absolute path
resolved_path = path.resolve()
# Check if path is within storage directory
storage_path = Path(settings.file_storage_path).resolve()
# Ensure the file is within the storage directory
return str(resolved_path).startswith(str(storage_path))
except Exception:
return False
def _generate_etag(self, path: Path, file_stat: os.stat_result) -> str:
"""Generate ETag for file based on path, size, and modification time."""
etag_data = f"{path}:{file_stat.st_size}:{file_stat.st_mtime}"
return hashlib.md5(etag_data.encode()).hexdigest()
def _check_not_modified(
self,
request: Request,
etag: str,
last_modified: datetime
) -> bool:
"""Check if file has not been modified based on conditional headers."""
# Check If-None-Match header
if_none_match = request.headers.get('if-none-match')
if if_none_match and etag in if_none_match:
return True
# Check If-Modified-Since header
if_modified_since = request.headers.get('if-modified-since')
if if_modified_since:
try:
client_time = datetime.strptime(
if_modified_since, '%a, %d %b %Y %H:%M:%S GMT'
)
if last_modified <= client_time:
return True
except ValueError:
pass
return False
def _get_content_type(self, path: Path, file_type: str) -> str:
"""Determine content type for file."""
# Try to guess from file extension
content_type, _ = mimetypes.guess_type(str(path))
if content_type:
return content_type
# Fallback based on file type
fallback_types = {
'image': 'image/jpeg',
'video': 'video/mp4',
'audio': 'audio/mpeg',
'document': 'application/pdf',
'archive': 'application/zip'
}
return fallback_types.get(file_type, 'application/octet-stream')
async def _serve_range_request(
self,
path: Path,
file_size: int,
range_header: str,
content_type: str,
original_filename: str,
inline: bool,
enable_caching: bool,
file_type: str,
etag: str,
last_modified: datetime
) -> StreamingResponse:
"""Serve file with range request support."""
try:
# Parse range header
ranges = self._parse_range_header(range_header, file_size)
if not ranges:
raise HTTPException(
status_code=status.HTTP_416_REQUESTED_RANGE_NOT_SATISFIABLE,
headers={"Content-Range": f"bytes */{file_size}"}
)
# For simplicity, only handle single range requests
start, end = ranges[0]
content_length = end - start + 1
# Create streaming response
async def range_streamer():
async with aiofiles.open(path, 'rb') as f:
await f.seek(start)
remaining = content_length
while remaining > 0:
chunk_size = min(8192, remaining)
chunk = await f.read(chunk_size)
if not chunk:
break
remaining -= len(chunk)
yield chunk
# Prepare headers
headers = {
"Content-Range": f"bytes {start}-{end}/{file_size}",
"Accept-Ranges": "bytes",
"Content-Length": str(content_length),
"ETag": f'"{etag}"',
"Last-Modified": last_modified.strftime('%a, %d %b %Y %H:%M:%S GMT')
}
# Add caching headers
if enable_caching:
cache_control = self.cache_control_headers.get(file_type, 'private, max-age=300')
headers["Cache-Control"] = cache_control
# Add content disposition
disposition = "inline" if inline else "attachment"
headers["Content-Disposition"] = f'{disposition}; filename="{original_filename}"'
return StreamingResponse(
range_streamer(),
status_code=status.HTTP_206_PARTIAL_CONTENT,
media_type=content_type,
headers=headers
)
except Exception as e:
logger.error(f"Failed to serve range request: {e}")
raise HTTPException(
status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
detail="Failed to serve range request"
)
async def _serve_full_file(
self,
path: Path,
file_size: int,
content_type: str,
original_filename: str,
inline: bool,
enable_caching: bool,
file_type: str,
etag: str,
last_modified: datetime
) -> StreamingResponse:
"""Serve full file."""
async def file_streamer():
async with aiofiles.open(path, 'rb') as f:
while chunk := await f.read(8192):
yield chunk
# Prepare headers
headers = {
"Content-Length": str(file_size),
"Accept-Ranges": "bytes",
"ETag": f'"{etag}"',
"Last-Modified": last_modified.strftime('%a, %d %b %Y %H:%M:%S GMT')
}
# Add caching headers
if enable_caching:
cache_control = self.cache_control_headers.get(file_type, 'private, max-age=300')
headers["Cache-Control"] = cache_control
# Add content disposition
disposition = "inline" if inline else "attachment"
headers["Content-Disposition"] = f'{disposition}; filename="{original_filename}"'
return StreamingResponse(
file_streamer(),
media_type=content_type,
headers=headers
)
def _parse_range_header(self, range_header: str, file_size: int) -> Optional[list]:
"""Parse HTTP Range header."""
try:
if not range_header.startswith('bytes='):
return None
ranges = []
range_specs = range_header[6:].split(',')
for range_spec in range_specs:
range_spec = range_spec.strip()
if '-' not in range_spec:
continue
start_str, end_str = range_spec.split('-', 1)
# Handle different range formats
if start_str and end_str:
# bytes=200-1023
start = int(start_str)
end = int(end_str)
elif start_str:
# bytes=200-
start = int(start_str)
end = file_size - 1
elif end_str:
# bytes=-500
start = file_size - int(end_str)
end = file_size - 1
else:
continue
# Validate range
if start < 0 or end >= file_size or start > end:
continue
ranges.append((start, end))
return ranges if ranges else None
except (ValueError, IndexError):
return None
def generate_file_url(
self,
file_id: str,
file_type: str,
inline: bool = False,
expires_in: Optional[int] = None
) -> str:
"""
Generate URL for file access.
Args:
file_id: File identifier
file_type: Type of file
inline: Whether to serve inline
expires_in: Optional expiration time in seconds
Returns:
File access URL
"""
base_url = f"/api/v1/files/{file_id}"
# Add query parameters
params = []
if inline:
params.append("inline=true")
if expires_in:
params.append(f"expires_in={expires_in}")
if params:
base_url += "?" + "&".join(params)
return base_url
def generate_thumbnail_url(self, file_id: str, size: str = "medium") -> str:
"""Generate thumbnail URL for image/video files."""
return f"/api/v1/files/{file_id}/thumbnail?size={size}"
def generate_streaming_url(self, file_id: str, quality: str = "auto") -> str:
"""Generate streaming URL for video files."""
return f"/api/v1/files/{file_id}/stream?quality={quality}"
# Global file serving manager
file_serving_manager = FileServingManager()
# Utility functions
async def serve_file_secure(
file_path: str,
file_type: str,
original_filename: str,
request: Request,
inline: bool = False,
enable_caching: bool = True,
user_id: Optional[str] = None
) -> StreamingResponse:
"""Serve file with security checks and optimizations."""
return await file_serving_manager.serve_file(
file_path=file_path,
file_type=file_type,
original_filename=original_filename,
request=request,
inline=inline,
enable_caching=enable_caching,
user_id=user_id
)
def generate_secure_file_url(
file_id: str,
file_type: str,
inline: bool = False,
expires_in: Optional[int] = None
) -> str:
"""Generate secure file URL."""
return file_serving_manager.generate_file_url(
file_id=file_id,
file_type=file_type,
inline=inline,
expires_in=expires_in
)
def generate_thumbnail_url(file_id: str, size: str = "medium") -> str:
"""Generate thumbnail URL."""
return file_serving_manager.generate_thumbnail_url(file_id, size)
def generate_streaming_url(file_id: str, quality: str = "auto") -> str:
"""Generate streaming URL."""
return file_serving_manager.generate_streaming_url(file_id, quality) |