fix: discard unused buffers in the ssh channel before disconnecting

server/http.go

@@ -12,16 +12,10 @@ import (
 	"strings"
 	"tunnel_pls/session"
 	"tunnel_pls/session/interaction"
+	"tunnel_pls/types"
 	"tunnel_pls/utils"
-
-	"golang.org/x/crypto/ssh"
 )
 
-var BadGatewayResponse = []byte("HTTP/1.1 502 Bad Gateway\r\n" +
-	"Content-Length: 11\r\n" +
-	"Content-Type: text/plain\r\n\r\n" +
-	"Bad Gateway")
-
 type CustomWriter struct {
 	RemoteAddr  net.Addr
 	writer      io.Writer
@@ -130,7 +124,7 @@ func isHTTPHeader(buf []byte) bool {
 }
 
 func (cw *CustomWriter) Write(p []byte) (int, error) {
-	if len(p) == len(BadGatewayResponse) && bytes.Equal(p, BadGatewayResponse) {
+	if len(p) == len(types.BadGatewayResponse) && bytes.Equal(p, types.BadGatewayResponse) {
 		return cw.writer.Write(p)
 	}
 
@@ -216,7 +210,7 @@ func NewHTTPServer() error {
 func Handler(conn net.Conn) {
 	defer func() {
 		err := conn.Close()
-		if err != nil {
+		if err != nil && !errors.Is(err, net.ErrClosed) {
 			log.Printf("Error closing connection: %v", err)
 			return
 		}
@@ -302,20 +296,8 @@ func forwardRequest(cw *CustomWriter, initialRequest *RequestHeaderFactory, sshS
 	channel, reqs, err := sshSession.Lifecycle.GetConnection().OpenChannel("forwarded-tcpip", payload)
 	if err != nil {
 		log.Printf("Failed to open forwarded-tcpip channel: %v", err)
-		sendBadGatewayResponse(cw)
 		return
 	}
-	defer func(channel ssh.Channel) {
-		err := channel.Close()
-		if err != nil {
-			if errors.Is(err, io.EOF) {
-				sendBadGatewayResponse(cw)
-				return
-			}
-			log.Println("Failed to close connection:", err)
-			return
-		}
-	}(channel)
 
 	go func() {
 		for req := range reqs {
@@ -352,11 +334,3 @@ func forwardRequest(cw *CustomWriter, initialRequest *RequestHeaderFactory, sshS
 	sshSession.Forwarder.HandleConnection(cw, channel, cw.RemoteAddr)
 	return
 }
-
-func sendBadGatewayResponse(writer io.Writer) {
-	_, err := writer.Write(BadGatewayResponse)
-	if err != nil {
-		log.Printf("failed to write Bad Gateway response: %v", err)
-		return
-	}
-}

session/forwarder/forwarder.go

@@ -38,6 +38,7 @@ type ForwardingController interface {
 	HandleConnection(dst io.ReadWriter, src ssh.Channel, remoteAddr net.Addr)
 	SetLifecycle(lifecycle Lifecycle)
 	CreateForwardedTCPIPPayload(origin net.Addr) []byte
+	WriteBadGatewayResponse(dst io.Writer)
 }
 
 func (f *Forwarder) SetLifecycle(lifecycle Lifecycle) {
@@ -76,7 +77,12 @@ func (f *Forwarder) AcceptTCPConnections() {
 
 func (f *Forwarder) HandleConnection(dst io.ReadWriter, src ssh.Channel, remoteAddr net.Addr) {
 	defer func(src ssh.Channel) {
-		err := src.Close()
+		_, err := io.Copy(io.Discard, src)
+		if err != nil {
+			log.Printf("Failed to discard connection: %v", err)
+		}
+
+		err = src.Close()
 		if err != nil && !errors.Is(err, io.EOF) {
 			log.Printf("Error closing connection: %v", err)
 		}
@@ -122,6 +128,14 @@ func (f *Forwarder) GetListener() net.Listener {
 	return f.Listener
 }
 
+func (f *Forwarder) WriteBadGatewayResponse(dst io.Writer) {
+	_, err := dst.Write(types.BadGatewayResponse)
+	if err != nil {
+		log.Printf("failed to write Bad Gateway response: %v", err)
+		return
+	}
+}
+
 func (f *Forwarder) Close() error {
 	if f.GetTunnelType() != types.HTTP {
 		return f.Listener.Close()

session/interaction/interaction.go

@@ -98,7 +98,6 @@ func (i *Interaction) HandleUserInput() {
 
 			if char == 8 || char == 127 {
 				if i.InputLength > 0 {
-					//i.CommandBuffer.Truncate(i.CommandBuffer.Len() - 1)
 					i.SendMessage("\b \b")
 				}
 				if i.CommandBuffer.Len() > 0 {

types/types.go

@@ -14,3 +14,8 @@ const (
 	HTTP TunnelType = "HTTP"
 	TCP  TunnelType = "TCP"
 )
+
+var BadGatewayResponse = []byte("HTTP/1.1 502 Bad Gateway\r\n" +
+	"Content-Length: 11\r\n" +
+	"Content-Type: text/plain\r\n\r\n" +
+	"Bad Gateway")