Clean up HTTP proxy (#125)

x/examples/http2transport/main.go

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

x/httpproxy/connect_handler.go

@@ -15,68 +15,26 @@
 package httpproxy
 
 import (
-	"context"
 	"fmt"
 	"io"
 	"net"
 	"net/http"
-	"strings"
 
 	"github.com/Jigsaw-Code/outline-sdk/transport"
 )
 
-type handler struct {
+type connectHandler struct {
 	dialer transport.StreamDialer
-	client http.Client
 }
 
-var _ http.Handler = (*handler)(nil)
+var _ http.Handler = (*connectHandler)(nil)
 
-// ServeHTTP implements [http.Handler].ServeHTTP for CONNECT requests, using the internal [transport.StreamDialer].
-func (h *handler) 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.handleConnect(proxyResp, proxyReq)
+func (h *connectHandler) ServeHTTP(proxyResp http.ResponseWriter, proxyReq *http.Request) {
+	if proxyReq.Method != http.MethodConnect {
+		proxyResp.Header().Add("Allow", "CONNECT")
+		http.Error(proxyResp, fmt.Sprintf("Method %v is not supported", proxyReq.Method), http.StatusMethodNotAllowed)
 		return
 	}
-	if proxyReq.URL.Host != "" {
-		h.handleHTTPProxyRequest(proxyResp, proxyReq)
-		return
-	}
-	http.Error(proxyResp, "Not Found", http.StatusNotFound)
-}
-
-func (h *handler) handleHTTPProxyRequest(proxyResp http.ResponseWriter, proxyReq *http.Request) {
-	// We create a new request that uses a relative path + Host header, instead of the absolute URL in the proxy request.
-	targetReq, err := http.NewRequestWithContext(proxyReq.Context(), proxyReq.Method, proxyReq.URL.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 {
-			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)
-		}
-	}
-	_, err = io.Copy(proxyResp, targetResp.Body)
-	if err != nil {
-		http.Error(proxyResp, "Failed write response", http.StatusServiceUnavailable)
-		return
-	}
-}
-
-func (h *handler) handleConnect(proxyResp http.ResponseWriter, proxyReq *http.Request) {
 	// Validate the target address.
 	_, portStr, err := net.SplitHostPort(proxyReq.Host)
 	if err != nil {
@@ -128,11 +86,5 @@ func (h *handler) handleConnect(proxyResp http.ResponseWriter, proxyReq *http.Re
 // The resulting handler is currently vulnerable to probing attacks. It's ok as a localhost proxy
 // but it may be vulnerable if used as a public proxy.
 func NewConnectHandler(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.Dial(ctx, addr)
-	}
-	return &handler{dialer, http.Client{Transport: &http.Transport{DialContext: dialContext}}}
+	return &connectHandler{dialer}
 }

x/httpproxy/forward_handler.go

@@ -0,0 +1,77 @@
+// Copyright 2023 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"
+	"strings"
+
+	"github.com/Jigsaw-Code/outline-sdk/transport"
+)
+
+type forwardHandler struct {
+	client http.Client
+}
+
+var _ http.Handler = (*forwardHandler)(nil)
+
+func (h *forwardHandler) ServeHTTP(proxyResp http.ResponseWriter, proxyReq *http.Request) {
+	if proxyReq.URL.Host == "" {
+		http.Error(proxyResp, "Must specify an absolute request target", http.StatusNotFound)
+		return
+	}
+	// We create a new request that uses a relative path + Host header, instead of the absolute URL in the proxy request.
+	targetReq, err := http.NewRequestWithContext(proxyReq.Context(), proxyReq.Method, proxyReq.URL.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 {
+			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)
+		}
+	}
+	_, err = io.Copy(proxyResp, targetResp.Body)
+	if err != nil {
+		http.Error(proxyResp, "Failed write response", http.StatusServiceUnavailable)
+		return
+	}
+}
+
+// NewForwardHandler creates a [http.Handler] that handles absolute HTTP requests using the given [http.Client].
+func NewForwardHandler(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.Dial(ctx, addr)
+	}
+	return &forwardHandler{http.Client{Transport: &http.Transport{DialContext: dialContext}}}
+}

x/httpproxy/proxy_handler.go

@@ -0,0 +1,48 @@
+// Copyright 2023 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 (
+	"net/http"
+
+	"github.com/Jigsaw-Code/outline-sdk/transport"
+)
+
+type proxyHandler struct {
+	connectHandler http.Handler
+	forwardHandler 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) {
+	// 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)
+		return
+	}
+	if proxyReq.URL.Host != "" {
+		h.forwardHandler.ServeHTTP(proxyResp, proxyReq)
+		return
+	}
+	http.Error(proxyResp, "Not Found", http.StatusNotFound)
+}
+
+// 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{
+		connectHandler: NewConnectHandler(dialer),
+		forwardHandler: NewForwardHandler(dialer),
+	}
+}

x/mobileproxy/mobileproxy.go

@@ -77,7 +77,7 @@ func RunProxy(localAddress string, transportConfig string) (*Proxy, error) {
 		return nil, fmt.Errorf("could not listen on address %v: %v", localAddress, err)
 	}
 
-	server := &http.Server{Handler: httpproxy.NewConnectHandler(dialer)}
+	server := &http.Server{Handler: httpproxy.NewProxyHandler(dialer)}
 	go server.Serve(listener)
 
 	host, portStr, err := net.SplitHostPort(listener.Addr().String())