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Secure URL generation utilities for file access.
This module provides utilities for generating secure, time-limited URLs
for file access with proper authentication and authorization checks.
"""
import hashlib
import hmac
import time
from datetime import datetime, timedelta
from typing import Optional, Dict, Any
from urllib.parse import urlencode
from ..core.config import get_settings
from ..core.logger import get_logger
settings = get_settings()
logger = get_logger(__name__)
class SecureURLGenerator:
"""Generator for secure, time-limited file access URLs."""
def __init__(self, secret_key: Optional[str] = None):
"""Initialize with secret key for URL signing."""
self.secret_key = secret_key or getattr(settings, 'url_signing_key', 'default-secret-key')
def generate_signed_url(
self,
file_id: str,
user_id: str,
file_type: str,
expires_in: int = 3600,
inline: bool = False,
additional_params: Optional[Dict[str, str]] = None
) -> str:
"""
Generate a signed URL for secure file access.
Args:
file_id: File identifier
user_id: User ID for access control
file_type: Type of file
expires_in: Expiration time in seconds
inline: Whether to serve inline
additional_params: Additional URL parameters
Returns:
Signed URL with expiration and security token
"""
try:
# Calculate expiration timestamp
expires_at = int(time.time()) + expires_in
# Base parameters
params = {
'user_id': user_id,
'expires': str(expires_at),
'file_type': file_type
}
if inline:
params['inline'] = 'true'
# Add additional parameters
if additional_params:
params.update(additional_params)
# Generate signature
signature = self._generate_signature(file_id, params)
params['signature'] = signature
# Build URL
base_url = f"/api/v1/files/{file_id}/secure"
query_string = urlencode(params)
signed_url = f"{base_url}?{query_string}"
logger.debug(
"Generated signed URL",
file_id=file_id,
user_id=user_id,
expires_in=expires_in,
url_length=len(signed_url)
)
return signed_url
except Exception as e:
logger.error(f"Failed to generate signed URL: {e}")
# Fallback to basic URL
return f"/api/v1/files/{file_id}/download"
def verify_signed_url(
self,
file_id: str,
params: Dict[str, str]
) -> Dict[str, Any]:
"""
Verify a signed URL and extract parameters.
Args:
file_id: File identifier
params: URL parameters to verify
Returns:
Dictionary with verification result and extracted data
"""
try:
# Check required parameters
required_params = ['user_id', 'expires', 'signature']
for param in required_params:
if param not in params:
return {
'valid': False,
'error': f'Missing required parameter: {param}'
}
# Check expiration
expires_at = int(params['expires'])
current_time = int(time.time())
if current_time > expires_at:
return {
'valid': False,
'error': 'URL has expired'
}
# Verify signature
signature = params.pop('signature')
expected_signature = self._generate_signature(file_id, params)
if not hmac.compare_digest(signature, expected_signature):
return {
'valid': False,
'error': 'Invalid signature'
}
# Extract data
return {
'valid': True,
'user_id': params['user_id'],
'file_type': params.get('file_type'),
'inline': params.get('inline', 'false').lower() == 'true',
'expires_at': datetime.fromtimestamp(expires_at)
}
except Exception as e:
logger.error(f"Failed to verify signed URL: {e}")
return {
'valid': False,
'error': 'Verification failed'
}
def _generate_signature(self, file_id: str, params: Dict[str, str]) -> str:
"""Generate HMAC signature for URL parameters."""
# Sort parameters for consistent signature
sorted_params = sorted(params.items())
# Create message to sign
message_parts = [file_id] + [f"{k}={v}" for k, v in sorted_params]
message = "&".join(message_parts)
# Generate HMAC signature
signature = hmac.new(
self.secret_key.encode(),
message.encode(),
hashlib.sha256
).hexdigest()
return signature
def generate_thumbnail_url(
self,
file_id: str,
user_id: str,
size: str = "medium",
expires_in: int = 86400 # 24 hours for thumbnails
) -> str:
"""Generate signed URL for thumbnail access."""
return self.generate_signed_url(
file_id=file_id,
user_id=user_id,
file_type="thumbnail",
expires_in=expires_in,
inline=True,
additional_params={'size': size}
)
def generate_streaming_url(
self,
file_id: str,
user_id: str,
quality: str = "auto",
expires_in: int = 7200 # 2 hours for streaming
) -> str:
"""Generate signed URL for streaming access."""
return self.generate_signed_url(
file_id=file_id,
user_id=user_id,
file_type="stream",
expires_in=expires_in,
inline=True,
additional_params={'quality': quality}
)
def generate_download_url(
self,
file_id: str,
user_id: str,
file_type: str,
expires_in: int = 3600,
inline: bool = False
) -> str:
"""Generate signed URL for download access."""
return self.generate_signed_url(
file_id=file_id,
user_id=user_id,
file_type=file_type,
expires_in=expires_in,
inline=inline
)
# Global URL generator instance
secure_url_generator = SecureURLGenerator()
# Utility functions
def generate_secure_file_url(
file_id: str,
user_id: str,
file_type: str,
expires_in: int = 3600,
inline: bool = False
) -> str:
"""Generate secure file URL with expiration."""
return secure_url_generator.generate_download_url(
file_id=file_id,
user_id=user_id,
file_type=file_type,
expires_in=expires_in,
inline=inline
)
def generate_secure_thumbnail_url(
file_id: str,
user_id: str,
size: str = "medium"
) -> str:
"""Generate secure thumbnail URL."""
return secure_url_generator.generate_thumbnail_url(
file_id=file_id,
user_id=user_id,
size=size
)
def generate_secure_streaming_url(
file_id: str,
user_id: str,
quality: str = "auto"
) -> str:
"""Generate secure streaming URL."""
return secure_url_generator.generate_streaming_url(
file_id=file_id,
user_id=user_id,
quality=quality
)
def verify_url_signature(file_id: str, params: Dict[str, str]) -> Dict[str, Any]:
"""Verify URL signature and extract parameters."""
return secure_url_generator.verify_signed_url(file_id, params) |