Add tunnelling HTTP requests to a Socks5 Proxy (#10)

Author: fripSide

README.md

@@ -18,6 +18,7 @@ Code based on the guide here: <https://medium.com/@mlowicki/http-s-proxy-in-gola
 - Can log request headers.
 - Can log failed authentication attempt details.
 - Printing version number.
+- Tunnel HTTP proxy to socks5 proxy
 
 ## Install
 
@@ -48,6 +49,10 @@ You can run the binary directly:
 
 ```bash
 ./simple-proxy
+
+# tunnel the http proxy to socks5 proxy
+# client -> localhost:7990 [http proxy] -> 127.0.0.1:7890 [socks5 proxy] -> server
+./simple-proxy -port 7990 -socks 127.0.0.1:7890
 ```
 
 ## Windows
@@ -86,6 +91,8 @@ Usage of simple-proxy:
     	log to standard error instead of files
   -port string
     	proxy port to listen on (default "8888")
+  -socks5 string
+    	proxy tunnel the http requests to a socks5 proxy (default "", feature off)
   -protocol string
     	proxy protocol (http or https) (default "http")
   -stderrthreshold value

go.mod

@@ -2,4 +2,7 @@ module github.com/jthomperoo/simple-proxy
 
 go 1.22
 
-require github.com/golang/glog v1.0.0
+require (
+	github.com/golang/glog v1.0.0
+	golang.org/x/net v0.30.0
+)

go.sum

@@ -1,2 +1,4 @@
 github.com/golang/glog v1.0.0 h1:nfP3RFugxnNRyKgeWd4oI1nYvXpxrx8ck8ZrcizshdQ=
 github.com/golang/glog v1.0.0/go.mod h1:EWib/APOK0SL3dFbYqvxE3UYd8E6s1ouQ7iEp/0LWV4=
+golang.org/x/net v0.30.0 h1:AcW1SDZMkb8IpzCdQUaIq2sP4sZ4zw+55h6ynffypl4=
+golang.org/x/net v0.30.0/go.mod h1:2wGyMJ5iFasEhkwi13ChkO/t1ECNC4X4eBKkVFyYFlU=

main.go

@@ -11,7 +11,7 @@ import (
 	"time"
 
 	"github.com/golang/glog"
-	"github.com/jthomperoo/simple-proxy/proxy"
+	my_proxy "github.com/jthomperoo/simple-proxy/proxy"
 )
 
 var (
@@ -36,6 +36,8 @@ func main() {
 	flag.StringVar(&bind, "bind", "0.0.0.0", "address to bind the proxy server to")
 	var port string
 	flag.StringVar(&port, "port", "8888", "proxy port to listen on")
+	var socks5 string
+	flag.StringVar(&socks5, "socks5", "", "SOCKS5 proxy for tunneling")
 	var certPath string
 	flag.StringVar(&certPath, "cert", "", "path to cert file")
 	var keyPath string
@@ -63,9 +65,11 @@ func main() {
 		glog.Fatalf("If using HTTPS protocol --cert and --key are required\n")
 	}
 
+	my_proxy.Socks5 = socks5
+
 	var handler http.Handler
 	if basicAuth == "" {
-		handler = &proxy.ProxyHandler{
+		handler = &my_proxy.ProxyHandler{
 			Timeout:    time.Duration(timeoutSecs) * time.Second,
 			LogAuth:    logAuth,
 			LogHeaders: logHeaders,
@@ -75,7 +79,7 @@ func main() {
 		if len(parts) < 2 {
 			glog.Fatalf("Invalid basic auth provided, must be in format 'username:password', auth: %s\n", basicAuth)
 		}
-		handler = &proxy.ProxyHandler{
+		handler = &my_proxy.ProxyHandler{
 			Timeout:    time.Duration(timeoutSecs) * time.Second,
 			Username:   &parts[0],
 			Password:   &parts[1],
@@ -93,6 +97,9 @@ func main() {
 
 	if protocol == httpProtocol {
 		glog.V(0).Infoln("Starting HTTP proxy...")
+		if socks5 != "" {
+			glog.V(0).Infof("Tunneling HTTP requests to SOCKS5 proxy: %s\n", socks5)
+		}
 		log.Fatal(server.ListenAndServe())
 	} else {
 		glog.V(0).Infoln("Starting HTTPS proxy...")

proxy/proxy.go

@@ -9,8 +9,12 @@ import (
 	"time"
 
 	"github.com/golang/glog"
+	net_proxy "golang.org/x/net/proxy"
 )
 
+// Using a socks5 proxy to tunnel the HTTP requests, e.g., 127.0.0.1:7890
+var Socks5 = ""
+
 func NewProxyHandler(timeoutSeconds int) *ProxyHandler {
 	return &ProxyHandler{
 		Timeout: time.Duration(timeoutSeconds) * time.Second,
@@ -55,7 +59,26 @@ func (p *ProxyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 func handleTunneling(w http.ResponseWriter, r *http.Request, timeout time.Duration) {
-	dest_conn, err := net.DialTimeout("tcp", r.Host, timeout)
+	var dest_conn net.Conn
+	var err error
+
+	// Check if the socks5 proxy is set
+	// Then tunnel to socks5 proxy
+	if Socks5 == "" {
+		dest_conn, err = net.DialTimeout("tcp", r.Host, timeout)
+	} else {
+		var socks5_dailer net_proxy.Dialer
+		socks5_dailer, err = net_proxy.SOCKS5("tcp", Socks5, nil, &net.Dialer{
+			Timeout:   timeout,
+			KeepAlive: 30 * time.Second,
+		})
+		if err != nil {
+			glog.Errorf("Failed to dail socks5 proxy %s, %s\n", Socks5, err.Error())
+			http.Error(w, err.Error(), http.StatusServiceUnavailable)
+			return
+		}
+		dest_conn, err = socks5_dailer.Dial("tcp", r.Host)
+	}
 	if err != nil {
 		glog.Errorf("Failed to dial host, %s\n", err.Error())
 		http.Error(w, err.Error(), http.StatusServiceUnavailable)