From 3a4f42e59e2ac6570a4de8e73c0bb20d34b2ae07 Mon Sep 17 00:00:00 2001
From: Imran Pochi <imranpochi@microsoft.com>
Date: Tue, 16 Jul 2024 17:58:59 +0530
Subject: [PATCH] http-connect: error to be written on connection

Incorrect error mesage from server to client because of hijack and error
message being written to http.Error or w.Write, instead the error
message should be written to the connection

fixes: 630

Signed-off-by: Imran Pochi <imranpochi@microsoft.com>
---
 pkg/server/tunnel.go | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/pkg/server/tunnel.go b/pkg/server/tunnel.go
index 5fb59a667..3d3ec18d2 100644
--- a/pkg/server/tunnel.go
+++ b/pkg/server/tunnel.go
@@ -53,13 +53,21 @@ func (t *Tunnel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "hijacking not supported", http.StatusInternalServerError)
 		return
 	}
-	w.WriteHeader(http.StatusOK)
 
 	conn, bufrw, err := hijacker.Hijack()
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
+
+	// Send the HTTP 200 OK status after a successful hijack
+	_, err = conn.Write([]byte("HTTP/1.1 200 Connection Established\r\n\r\n"))
+	if err != nil {
+		klog.ErrorS(err, "failed to send 200 connection established")
+		conn.Close()
+		return
+	}
+
 	var closeOnce sync.Once
 	defer closeOnce.Do(func() { conn.Close() })
 
@@ -78,7 +86,9 @@ func (t *Tunnel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	klog.V(4).Infof("Set pending(rand=%d) to %v", random, w)
 	backend, err := t.Server.getBackend(r.Host)
 	if err != nil {
-		http.Error(w, fmt.Sprintf("currently no tunnels available: %v", err), http.StatusInternalServerError)
+		klog.ErrorS(err, "no tunnels available")
+		conn.Write([]byte(fmt.Sprintf("HTTP/1.1 500 Internal Server Error\r\nContent-Type: text/plain\r\n\r\ncurrently no tunnels available: %v", err)))
+		conn.Close()
 		return
 	}
 	closed := make(chan struct{})