Fix POST requests by using standard HTTP tunneling instead of unconditional Hijack

cmd/server/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"io"
 	"log"
@@ -91,9 +92,13 @@ func startHttpProxy(port string) {
 		}
 		slug := parts[0]
 
+		log.Printf("Request Host: %s, Extracted Slug: %s", host, slug)
+
 		tunnel, ok := manager.Get(slug)
 		if !ok {
+			log.Printf("Tunnel not found for slug: %s", slug)
 			// Serve 404 page
+			w.WriteHeader(http.StatusNotFound)
 			http.ServeFile(w, r, "./cmd/server/static/404.html")
 			return
 		}
@@ -125,21 +130,15 @@ func startHttpProxy(port string) {
 		// But typically `gliderlabs/ssh` is for allowing the server to be a jump host.
 		// We want to be an HTTP Gateway.
 
-		// 1. Hijack the connection to handle bidirectional traffic (WebSockets)
-		hijacker, ok := w.(http.Hijacker)
-		if !ok {
-			http.Error(w, "Hijacking not supported", http.StatusInternalServerError)
-			return
-		}
-		clientConn, bufrw, err := hijacker.Hijack()
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusServiceUnavailable)
-			return
-		}
-		defer clientConn.Close()
+		// Panic recovery
+		defer func() {
+			if r := recover(); r != nil {
+				log.Printf("Recovered from panic in handler: %v", r)
+				http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+			}
+		}()
 
 		// 2. Open channel to client
-		// "forwarded-tcpip" arguments:
 		destHost := "0.0.0.0"
 		destPort := tunnel.LocalPort
 		srcHost := "127.0.0.1"
@@ -161,36 +160,82 @@ func startHttpProxy(port string) {
 		defer ch.Close()
 		go gossh.DiscardRequests(reqs)
 
-		var wg sync.WaitGroup
-		wg.Add(2)
+		// Check if it is a WebSocket Upgrade
+		isWebSocket := false
+		if strings.ToLower(r.Header.Get("Upgrade")) == "websocket" {
+			isWebSocket = true
+		}
 
-		// 3. Browser -> Backend (Write request + Copy raw stream)
-		go func() {
-			defer wg.Done()
-			// Write the initial request (Method, Path, Headers)
-			// This sets up the handshake or request.
-			// Note: We use r.Write to reconstruct the request line and headers.
-			// For WebSockets, the Body is empty, so this writes headers and returns.
-			// For POSTs, it writes headers and tries to copy Body.
-			if err := r.Write(ch); err != nil {
-				log.Printf("Error writing request to backend: %v", err)
+		if isWebSocket {
+			// WEBSOCKET STRATEGY: Hijack and bidirectional copy
+			hijacker, ok := w.(http.Hijacker)
+			if !ok {
+				http.Error(w, "Hijacking not supported", http.StatusInternalServerError)
 				return
 			}
-			// Important: Continue copying any subsequent data (like WebSocket frames)
-			// from the hijacked buffer/connection to the channel.
-			io.Copy(ch, bufrw)
-			// e.g. when browser closes or stops sending, we are done here.
-		}()
+			clientConn, bufrw, err := hijacker.Hijack()
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusServiceUnavailable)
+				return
+			}
+			defer clientConn.Close()
 
-		// 4. Backend -> Browser (Copy raw stream)
-		go func() {
-			defer wg.Done()
-			io.Copy(clientConn, ch)
-			// When backend closes connection, close browser connection
-			clientConn.Close()
-		}()
+			// Reconstruct request line and headers to send to backend
+			// We can use r.Write but it writes to the channel
+			if err := r.Write(ch); err != nil {
+				log.Printf("Error writing websocket request to backend: %v", err)
+				return
+			}
 
-		wg.Wait()
+			var wg sync.WaitGroup
+			wg.Add(2)
+
+			// Copy existing buffer from hijack + future reads -> backend
+			go func() {
+				defer wg.Done()
+				if bufrw.Reader.Buffered() > 0 {
+					io.CopyN(ch, bufrw, int64(bufrw.Reader.Buffered()))
+				}
+				io.Copy(ch, clientConn)
+			}()
+
+			// Backend -> Browser
+			go func() {
+				defer wg.Done()
+				io.Copy(clientConn, ch)
+			}()
+
+			wg.Wait()
+			return
+		}
+
+		// STANDARD HTTP STRATEGY: Request/Response Tunneling
+		// 1. Write Request to Channel (simulating wire)
+		if err := r.Write(ch); err != nil {
+			log.Printf("Error writing request to backend: %v", err)
+			http.Error(w, "Gateway Error", http.StatusBadGateway)
+			return
+		}
+
+		// 2. Read Response from Channel (parsing wire)
+		resp, err := http.ReadResponse(bufio.NewReader(ch), r)
+		if err != nil {
+			log.Printf("Error reading response from backend: %v", err)
+			http.Error(w, "Bad Gateway", http.StatusBadGateway)
+			return
+		}
+		defer resp.Body.Close()
+
+		// 3. Copy Headers to `w`
+		for k, vv := range resp.Header {
+			for _, v := range vv {
+				w.Header().Add(k, v)
+			}
+		}
+		w.WriteHeader(resp.StatusCode)
+
+		// 4. Copy Body to `w`
+		io.Copy(w, resp.Body)
 
 	})