JezK
Edit File: proxy_fix.py
""" X-Forwarded-For Proxy Fix ========================= This module provides a middleware that adjusts the WSGI environ based on ``X-Forwarded-`` headers that proxies in front of an application may set. When an application is running behind a proxy server, WSGI may see the request as coming from that server rather than the real client. Proxies set various headers to track where the request actually came from. This middleware should only be used if the application is actually behind such a proxy, and should be configured with the number of proxies that are chained in front of it. Not all proxies set all the headers. Since incoming headers can be faked, you must set how many proxies are setting each header so the middleware knows what to trust. .. autoclass:: ProxyFix :copyright: 2007 Pallets :license: BSD-3-Clause """ import typing as t from ..http import parse_list_header if t.TYPE_CHECKING: from _typeshed.wsgi import StartResponse from _typeshed.wsgi import WSGIApplication from _typeshed.wsgi import WSGIEnvironment class ProxyFix: """Adjust the WSGI environ based on ``X-Forwarded-`` that proxies in front of the application may set. - ``X-Forwarded-For`` sets ``REMOTE_ADDR``. - ``X-Forwarded-Proto`` sets ``wsgi.url_scheme``. - ``X-Forwarded-Host`` sets ``HTTP_HOST``, ``SERVER_NAME``, and ``SERVER_PORT``. - ``X-Forwarded-Port`` sets ``HTTP_HOST`` and ``SERVER_PORT``. - ``X-Forwarded-Prefix`` sets ``SCRIPT_NAME``. You must tell the middleware how many proxies set each header so it knows what values to trust. It is a security issue to trust values that came from the client rather than a proxy. The original values of the headers are stored in the WSGI environ as ``werkzeug.proxy_fix.orig``, a dict. :param app: The WSGI application to wrap. :param x_for: Number of values to trust for ``X-Forwarded-For``. :param x_proto: Number of values to trust for ``X-Forwarded-Proto``. :param x_host: Number of values to trust for ``X-Forwarded-Host``. :param x_port: Number of values to trust for ``X-Forwarded-Port``. :param x_prefix: Number of values to trust for ``X-Forwarded-Prefix``. .. code-block:: python from werkzeug.middleware.proxy_fix import ProxyFix # App is behind one proxy that sets the -For and -Host headers. app = ProxyFix(app, x_for=1, x_host=1) .. versionchanged:: 1.0 Deprecated code has been removed: * The ``num_proxies`` argument and attribute. * The ``get_remote_addr`` method. * The environ keys ``orig_remote_addr``, ``orig_wsgi_url_scheme``, and ``orig_http_host``. .. versionchanged:: 0.15 All headers support multiple values. The ``num_proxies`` argument is deprecated. Each header is configured with a separate number of trusted proxies. .. versionchanged:: 0.15 Original WSGI environ values are stored in the ``werkzeug.proxy_fix.orig`` dict. ``orig_remote_addr``, ``orig_wsgi_url_scheme``, and ``orig_http_host`` are deprecated and will be removed in 1.0. .. versionchanged:: 0.15 Support ``X-Forwarded-Port`` and ``X-Forwarded-Prefix``. .. versionchanged:: 0.15 ``X-Forwarded-Host`` and ``X-Forwarded-Port`` modify ``SERVER_NAME`` and ``SERVER_PORT``. """ def __init__( self, app: "WSGIApplication", x_for: int = 1, x_proto: int = 1, x_host: int = 0, x_port: int = 0, x_prefix: int = 0, ) -> None: self.app = app self.x_for = x_for self.x_proto = x_proto self.x_host = x_host self.x_port = x_port self.x_prefix = x_prefix def _get_real_value(self, trusted: int, value: t.Optional[str]) -> t.Optional[str]: """Get the real value from a list header based on the configured number of trusted proxies. :param trusted: Number of values to trust in the header. :param value: Comma separated list header value to parse. :return: The real value, or ``None`` if there are fewer values than the number of trusted proxies. .. versionchanged:: 1.0 Renamed from ``_get_trusted_comma``. .. versionadded:: 0.15 """ if not (trusted and value): return None values = parse_list_header(value) if len(values) >= trusted: return values[-trusted] return None def __call__( self, environ: "WSGIEnvironment", start_response: "StartResponse" ) -> t.Iterable[bytes]: """Modify the WSGI environ based on the various ``Forwarded`` headers before calling the wrapped application. Store the original environ values in ``werkzeug.proxy_fix.orig_{key}``. """ environ_get = environ.get orig_remote_addr = environ_get("REMOTE_ADDR") orig_wsgi_url_scheme = environ_get("wsgi.url_scheme") orig_http_host = environ_get("HTTP_HOST") environ.update( { "werkzeug.proxy_fix.orig": { "REMOTE_ADDR": orig_remote_addr, "wsgi.url_scheme": orig_wsgi_url_scheme, "HTTP_HOST": orig_http_host, "SERVER_NAME": environ_get("SERVER_NAME"), "SERVER_PORT": environ_get("SERVER_PORT"), "SCRIPT_NAME": environ_get("SCRIPT_NAME"), } } ) x_for = self._get_real_value(self.x_for, environ_get("HTTP_X_FORWARDED_FOR")) if x_for: environ["REMOTE_ADDR"] = x_for x_proto = self._get_real_value( self.x_proto, environ_get("HTTP_X_FORWARDED_PROTO") ) if x_proto: environ["wsgi.url_scheme"] = x_proto x_host = self._get_real_value(self.x_host, environ_get("HTTP_X_FORWARDED_HOST")) if x_host: environ["HTTP_HOST"] = environ["SERVER_NAME"] = x_host # "]" to check for IPv6 address without port if ":" in x_host and not x_host.endswith("]"): environ["SERVER_NAME"], environ["SERVER_PORT"] = x_host.rsplit(":", 1) x_port = self._get_real_value(self.x_port, environ_get("HTTP_X_FORWARDED_PORT")) if x_port: host = environ.get("HTTP_HOST") if host: # "]" to check for IPv6 address without port if ":" in host and not host.endswith("]"): host = host.rsplit(":", 1)[0] environ["HTTP_HOST"] = f"{host}:{x_port}" environ["SERVER_PORT"] = x_port x_prefix = self._get_real_value( self.x_prefix, environ_get("HTTP_X_FORWARDED_PREFIX") ) if x_prefix: environ["SCRIPT_NAME"] = x_prefix return self.app(environ, start_response)