Merge pull request #177 from Jigsaw-Code/daniellacosse/path_forwarding

forward URL path through the proxy

x/examples/http2transport/main.go

@@ -45,7 +45,9 @@ func main() {
 	defer listener.Close()
 	log.Printf("Proxy listening on %v", listener.Addr().String())
 
-	server := http.Server{Handler: httpproxy.NewProxyHandler(dialer)}
+	handler := httpproxy.NewProxyHandler(dialer)
+	handler.FallbackHandler = httpproxy.NewPathHandler(dialer)
+	server := http.Server{Handler: handler}
 	go func() {
 		if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
 			log.Fatalf("Error running web server: %v", err)

x/httpproxy/path_handler.go

@@ -0,0 +1,89 @@
+// Copyright 2024 Jigsaw Operations LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package httpproxy
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/Jigsaw-Code/outline-sdk/transport"
+)
+
+type pathHandler struct {
+	client http.Client
+}
+
+var _ http.Handler = (*pathHandler)(nil)
+
+func (h *pathHandler) ServeHTTP(proxyResp http.ResponseWriter, proxyReq *http.Request) {
+	requestURL := strings.TrimPrefix(proxyReq.URL.Path, "/")
+	if requestURL == "" {
+		http.Error(proxyResp, "Empty URL", http.StatusBadRequest)
+		return
+	}
+	if proxyReq.URL.RawQuery != "" {
+		requestURL += "?" + proxyReq.URL.RawQuery
+	}
+	targetURL, err := url.Parse(requestURL)
+	if err != nil {
+		http.Error(proxyResp, "Invalid target URL", http.StatusBadRequest)
+		return
+	}
+	// We create a new request that uses the path of the proxy request.
+	targetReq, err := http.NewRequestWithContext(proxyReq.Context(), proxyReq.Method, targetURL.String(), proxyReq.Body)
+	if err != nil {
+		http.Error(proxyResp, "Error creating target request", http.StatusInternalServerError)
+		return
+	}
+	for key, values := range proxyReq.Header {
+		for _, value := range values {
+			// Host header is set by the HTTP client in client.Do.
+			targetReq.Header.Add(key, value)
+		}
+	}
+	targetResp, err := h.client.Do(targetReq)
+	if err != nil {
+		http.Error(proxyResp, "Failed to fetch destination", http.StatusServiceUnavailable)
+		return
+	}
+	defer targetResp.Body.Close()
+	for key, values := range targetResp.Header {
+		for _, value := range values {
+			proxyResp.Header().Add(key, value)
+		}
+	}
+	proxyResp.WriteHeader(targetResp.StatusCode)
+	_, err = io.Copy(proxyResp, targetResp.Body)
+	if err != nil {
+		http.Error(proxyResp, "Failed write response", http.StatusServiceUnavailable)
+		return
+	}
+}
+
+// NewPathHandler creates a [http.Handler] that resolves the URL path as an absolute URL using the given [http.Client].
+func NewPathHandler(dialer transport.StreamDialer) http.Handler {
+	dialContext := func(ctx context.Context, network, addr string) (net.Conn, error) {
+		if !strings.HasPrefix(network, "tcp") {
+			return nil, fmt.Errorf("protocol not supported: %v", network)
+		}
+		return dialer.DialStream(ctx, addr)
+	}
+	return &pathHandler{http.Client{Transport: &http.Transport{DialContext: dialContext}}}
+}

x/httpproxy/proxy_handler.go

@@ -20,13 +20,14 @@ import (
 	"github.com/Jigsaw-Code/outline-sdk/transport"
 )
 
-type proxyHandler struct {
-	connectHandler http.Handler
-	forwardHandler http.Handler
+type ProxyHandler struct {
+	connectHandler  http.Handler
+	forwardHandler  http.Handler
+	FallbackHandler http.Handler
 }
 
 // ServeHTTP implements [http.Handler].ServeHTTP for CONNECT and absolute URL requests, using the internal [transport.StreamDialer].
-func (h *proxyHandler) ServeHTTP(proxyResp http.ResponseWriter, proxyReq *http.Request) {
+func (h *ProxyHandler) ServeHTTP(proxyResp http.ResponseWriter, proxyReq *http.Request) {
 	// TODO(fortuna): For public services (not local), we need authentication and drain on failures to avoid fingerprinting.
 	if proxyReq.Method == http.MethodConnect {
 		h.connectHandler.ServeHTTP(proxyResp, proxyReq)
@@ -36,12 +37,16 @@ func (h *proxyHandler) ServeHTTP(proxyResp http.ResponseWriter, proxyReq *http.R
 		h.forwardHandler.ServeHTTP(proxyResp, proxyReq)
 		return
 	}
-	http.Error(proxyResp, "Not Found", http.StatusNotFound)
+	if h.FallbackHandler != nil {
+		h.FallbackHandler.ServeHTTP(proxyResp, proxyReq)
+		return
+	}
+	http.NotFound(proxyResp, proxyReq)
 }
 
 // NewProxyHandler creates a [http.Handler] that works as a web proxy using the given dialer to deach the destination.
-func NewProxyHandler(dialer transport.StreamDialer) http.Handler {
-	return &proxyHandler{
+func NewProxyHandler(dialer transport.StreamDialer) *ProxyHandler {
+	return &ProxyHandler{
 		connectHandler: NewConnectHandler(dialer),
 		forwardHandler: NewForwardHandler(dialer),
 	}