JezK
Edit File: http_proxy.py
""" Basic HTTP Proxy ================ .. autoclass:: ProxyMiddleware :copyright: 2007 Pallets :license: BSD-3-Clause """ import typing as t from http import client from ..datastructures import EnvironHeaders from ..http import is_hop_by_hop_header from ..urls import url_parse from ..urls import url_quote from ..wsgi import get_input_stream if t.TYPE_CHECKING: from _typeshed.wsgi import StartResponse from _typeshed.wsgi import WSGIApplication from _typeshed.wsgi import WSGIEnvironment class ProxyMiddleware: """Proxy requests under a path to an external server, routing other requests to the app. This middleware can only proxy HTTP requests, as HTTP is the only protocol handled by the WSGI server. Other protocols, such as WebSocket requests, cannot be proxied at this layer. This should only be used for development, in production a real proxy server should be used. The middleware takes a dict mapping a path prefix to a dict describing the host to be proxied to:: app = ProxyMiddleware(app, { "/static/": { "target": "http://127.0.0.1:5001/", } }) Each host has the following options: ``target``: The target URL to dispatch to. This is required. ``remove_prefix``: Whether to remove the prefix from the URL before dispatching it to the target. The default is ``False``. ``host``: ``"<auto>"`` (default): The host header is automatically rewritten to the URL of the target. ``None``: The host header is unmodified from the client request. Any other value: The host header is overwritten with the value. ``headers``: A dictionary of headers to be sent with the request to the target. The default is ``{}``. ``ssl_context``: A :class:`ssl.SSLContext` defining how to verify requests if the target is HTTPS. The default is ``None``. In the example above, everything under ``"/static/"`` is proxied to the server on port 5001. The host header is rewritten to the target, and the ``"/static/"`` prefix is removed from the URLs. :param app: The WSGI application to wrap. :param targets: Proxy target configurations. See description above. :param chunk_size: Size of chunks to read from input stream and write to target. :param timeout: Seconds before an operation to a target fails. .. versionadded:: 0.14 """ def __init__( self, app: "WSGIApplication", targets: t.Mapping[str, t.Dict[str, t.Any]], chunk_size: int = 2 << 13, timeout: int = 10, ) -> None: def _set_defaults(opts: t.Dict[str, t.Any]) -> t.Dict[str, t.Any]: opts.setdefault("remove_prefix", False) opts.setdefault("host", "<auto>") opts.setdefault("headers", {}) opts.setdefault("ssl_context", None) return opts self.app = app self.targets = { f"/{k.strip('/')}/": _set_defaults(v) for k, v in targets.items() } self.chunk_size = chunk_size self.timeout = timeout def proxy_to( self, opts: t.Dict[str, t.Any], path: str, prefix: str ) -> "WSGIApplication": target = url_parse(opts["target"]) host = t.cast(str, target.ascii_host) def application( environ: "WSGIEnvironment", start_response: "StartResponse" ) -> t.Iterable[bytes]: headers = list(EnvironHeaders(environ).items()) headers[:] = [ (k, v) for k, v in headers if not is_hop_by_hop_header(k) and k.lower() not in ("content-length", "host") ] headers.append(("Connection", "close")) if opts["host"] == "<auto>": headers.append(("Host", host)) elif opts["host"] is None: headers.append(("Host", environ["HTTP_HOST"])) else: headers.append(("Host", opts["host"])) headers.extend(opts["headers"].items()) remote_path = path if opts["remove_prefix"]: remote_path = remote_path[len(prefix) :].lstrip("/") remote_path = f"{target.path.rstrip('/')}/{remote_path}" content_length = environ.get("CONTENT_LENGTH") chunked = False if content_length not in ("", None): headers.append(("Content-Length", content_length)) # type: ignore elif content_length is not None: headers.append(("Transfer-Encoding", "chunked")) chunked = True try: if target.scheme == "http": con = client.HTTPConnection( host, target.port or 80, timeout=self.timeout ) elif target.scheme == "https": con = client.HTTPSConnection( host, target.port or 443, timeout=self.timeout, context=opts["ssl_context"], ) else: raise RuntimeError( "Target scheme must be 'http' or 'https', got" f" {target.scheme!r}." ) con.connect() remote_url = url_quote(remote_path) querystring = environ["QUERY_STRING"] if querystring: remote_url = f"{remote_url}?{querystring}" con.putrequest(environ["REQUEST_METHOD"], remote_url, skip_host=True) for k, v in headers: if k.lower() == "connection": v = "close" con.putheader(k, v) con.endheaders() stream = get_input_stream(environ) while True: data = stream.read(self.chunk_size) if not data: break if chunked: con.send(b"%x\r\n%s\r\n" % (len(data), data)) else: con.send(data) resp = con.getresponse() except OSError: from ..exceptions import BadGateway return BadGateway()(environ, start_response) start_response( f"{resp.status} {resp.reason}", [ (k.title(), v) for k, v in resp.getheaders() if not is_hop_by_hop_header(k) ], ) def read() -> t.Iterator[bytes]: while True: try: data = resp.read(self.chunk_size) except OSError: break if not data: break yield data return read() return application def __call__( self, environ: "WSGIEnvironment", start_response: "StartResponse" ) -> t.Iterable[bytes]: path = environ["PATH_INFO"] app = self.app for prefix, opts in self.targets.items(): if path.startswith(prefix): app = self.proxy_to(opts, path, prefix) break return app(environ, start_response)