134 lines
4.5 KiB
Python
134 lines
4.5 KiB
Python
import re
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import os
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from fastapi import Request
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from starlette.middleware.base import BaseHTTPMiddleware
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from typing import Dict
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class SecurityHeadersMiddleware(BaseHTTPMiddleware):
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async def dispatch(self, request: Request, call_next):
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response = await call_next(request)
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response.headers.update(set_security_headers())
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return response
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def set_security_headers() -> Dict[str, str]:
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"""
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Sets security headers based on environment variables.
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This function reads specific environment variables and uses their values
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to set corresponding security headers. The headers that can be set are:
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- cache-control
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- permissions-policy
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- strict-transport-security
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- referrer-policy
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- x-content-type-options
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- x-download-options
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- x-frame-options
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- x-permitted-cross-domain-policies
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- content-security-policy
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Each environment variable is associated with a specific setter function
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that constructs the header. If the environment variable is set, the
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corresponding header is added to the options dictionary.
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Returns:
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dict: A dictionary containing the security headers and their values.
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"""
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options = {}
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header_setters = {
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"CACHE_CONTROL": set_cache_control,
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"HSTS": set_hsts,
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"PERMISSIONS_POLICY": set_permissions_policy,
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"REFERRER_POLICY": set_referrer,
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"XCONTENT_TYPE": set_xcontent_type,
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"XDOWNLOAD_OPTIONS": set_xdownload_options,
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"XFRAME_OPTIONS": set_xframe,
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"XPERMITTED_CROSS_DOMAIN_POLICIES": set_xpermitted_cross_domain_policies,
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"CONTENT_SECURITY_POLICY": set_content_security_policy,
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}
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for env_var, setter in header_setters.items():
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value = os.environ.get(env_var, None)
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if value:
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header = setter(value)
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if header:
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options.update(header)
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return options
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# Set HTTP Strict Transport Security(HSTS) response header
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def set_hsts(value: str):
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pattern = r"^max-age=(\d+)(;includeSubDomains)?(;preload)?$"
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match = re.match(pattern, value, re.IGNORECASE)
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if not match:
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value = "max-age=31536000;includeSubDomains"
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return {"Strict-Transport-Security": value}
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# Set X-Frame-Options response header
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def set_xframe(value: str):
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pattern = r"^(DENY|SAMEORIGIN)$"
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match = re.match(pattern, value, re.IGNORECASE)
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if not match:
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value = "DENY"
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return {"X-Frame-Options": value}
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# Set Permissions-Policy response header
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def set_permissions_policy(value: str):
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pattern = r"^(?:(accelerometer|autoplay|camera|clipboard-read|clipboard-write|fullscreen|geolocation|gyroscope|magnetometer|microphone|midi|payment|picture-in-picture|sync-xhr|usb|xr-spatial-tracking)=\((self)?\),?)*$"
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match = re.match(pattern, value, re.IGNORECASE)
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if not match:
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value = "none"
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return {"Permissions-Policy": value}
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# Set Referrer-Policy response header
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def set_referrer(value: str):
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pattern = r"^(no-referrer|no-referrer-when-downgrade|origin|origin-when-cross-origin|same-origin|strict-origin|strict-origin-when-cross-origin|unsafe-url)$"
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match = re.match(pattern, value, re.IGNORECASE)
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if not match:
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value = "no-referrer"
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return {"Referrer-Policy": value}
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# Set Cache-Control response header
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def set_cache_control(value: str):
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pattern = r"^(public|private|no-cache|no-store|must-revalidate|proxy-revalidate|max-age=\d+|s-maxage=\d+|no-transform|immutable)(,\s*(public|private|no-cache|no-store|must-revalidate|proxy-revalidate|max-age=\d+|s-maxage=\d+|no-transform|immutable))*$"
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match = re.match(pattern, value, re.IGNORECASE)
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if not match:
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value = "no-store, max-age=0"
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return {"Cache-Control": value}
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# Set X-Download-Options response header
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def set_xdownload_options(value: str):
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if value != "noopen":
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value = "noopen"
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return {"X-Download-Options": value}
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# Set X-Content-Type-Options response header
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def set_xcontent_type(value: str):
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if value != "nosniff":
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value = "nosniff"
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return {"X-Content-Type-Options": value}
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# Set X-Permitted-Cross-Domain-Policies response header
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def set_xpermitted_cross_domain_policies(value: str):
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pattern = r"^(none|master-only|by-content-type|by-ftp-filename)$"
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match = re.match(pattern, value, re.IGNORECASE)
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if not match:
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value = "none"
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return {"X-Permitted-Cross-Domain-Policies": value}
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# Set Content-Security-Policy response header
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def set_content_security_policy(value: str):
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return {"Content-Security-Policy": value}
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