From 2e736897624e8d529f8e441deba123b1dbfbb594 Mon Sep 17 00:00:00 2001
From: Evan Reichard <evan@reichard.io>
Date: Mon, 22 Sep 2025 23:04:15 -0400
Subject: [PATCH] http vs tcp tunnel

---
 client/client.go |   2 +-
 cmd/tunnel.go    |   3 --
 tunnel/http.go   | 104 +++++++++++++++++++++++++++++++++++++++++++++++
 tunnel/tunnel.go |  39 ++++++++++++++----
 4 files changed, 135 insertions(+), 13 deletions(-)
 create mode 100644 tunnel/http.go

diff --git a/client/client.go b/client/client.go
index 1e0aeec..c9258f1 100644
--- a/client/client.go
+++ b/client/client.go
@@ -41,5 +41,5 @@ func NewTunnel(cfg *config.ClientConfig) (*tunnel.Tunnel, error) {
 		return nil, fmt.Errorf("failed to connect: %v", err)
 	}
 
-	return tunnel.NewClientTunnel(cfg.TunnelName, cfg.TunnelTarget, serverConn), nil
+	return tunnel.NewClientTunnel(cfg.TunnelName, cfg.TunnelTarget, serverConn)
 }
diff --git a/cmd/tunnel.go b/cmd/tunnel.go
index 48ace87..1643366 100644
--- a/cmd/tunnel.go
+++ b/cmd/tunnel.go
@@ -22,9 +22,6 @@ var tunnelCmd = &cobra.Command{
 		if err != nil {
 			log.Fatal("failed to create tunnel:", err)
 		}
-
-		// Start Tunnel
-		log.Infof("creating TCP tunnel: %s -> %s", cfg.TunnelName, cfg.TunnelTarget)
 		tunnel.Start()
 	},
 }
diff --git a/tunnel/http.go b/tunnel/http.go
new file mode 100644
index 0000000..dfb90e3
--- /dev/null
+++ b/tunnel/http.go
@@ -0,0 +1,104 @@
+package tunnel
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync"
+)
+
+func HTTPConnectionBuilder(targetURL *url.URL) (ConnBuilder, error) {
+	multiConnListener := newMultiConnListener()
+
+	// Create Reverse Proxy
+	proxy := &httputil.ReverseProxy{
+		Director: func(req *http.Request) {
+			req.Host = targetURL.Host
+			req.URL.Host = targetURL.Host
+			req.URL.Scheme = targetURL.Scheme
+		},
+		ErrorHandler: func(w http.ResponseWriter, r *http.Request, err error) {
+			http.Error(w, fmt.Sprintf("Proxy error: %v", err), http.StatusBadGateway)
+		},
+	}
+
+	// Start HTTP Proxy
+	go func() {
+		defer multiConnListener.Close()
+		_ = http.Serve(multiConnListener, proxy)
+	}()
+
+	// Return Connection Builder
+	return func() (conn io.ReadWriteCloser, err error) {
+		clientConn, serverConn := net.Pipe()
+
+		if err := multiConnListener.addConn(serverConn); err != nil {
+			_ = clientConn.Close()
+			_ = serverConn.Close()
+			return nil, err
+		}
+
+		return clientConn, nil
+	}, nil
+}
+
+type multiConnListener struct {
+	connCh chan net.Conn
+	closed chan struct{}
+	once   sync.Once
+}
+
+func newMultiConnListener() *multiConnListener {
+	return &multiConnListener{
+		connCh: make(chan net.Conn, 100),
+		closed: make(chan struct{}),
+	}
+}
+
+func (l *multiConnListener) Accept() (net.Conn, error) {
+	select {
+	case conn := <-l.connCh:
+		if conn == nil {
+			return nil, fmt.Errorf("listener closed")
+		}
+		return conn, nil
+	case <-l.closed:
+		return nil, fmt.Errorf("listener closed")
+	}
+}
+
+func (l *multiConnListener) Close() error {
+	l.once.Do(func() {
+		close(l.closed)
+		// Drain any remaining connections
+		go func() {
+			for conn := range l.connCh {
+				if conn != nil {
+					conn.Close()
+				}
+			}
+		}()
+		close(l.connCh)
+	})
+	return nil
+}
+
+func (l *multiConnListener) Addr() net.Addr {
+	return &net.TCPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 0}
+}
+
+func (l *multiConnListener) addConn(conn net.Conn) error {
+	select {
+	case l.connCh <- conn:
+		return nil
+	case <-l.closed:
+		conn.Close()
+		return fmt.Errorf("listener is closed")
+	default:
+		conn.Close()
+		return fmt.Errorf("connection queue full")
+	}
+}
diff --git a/tunnel/tunnel.go b/tunnel/tunnel.go
index 785a9c8..19d2893 100644
--- a/tunnel/tunnel.go
+++ b/tunnel/tunnel.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"net/url"
 	"sync"
 
 	"github.com/gorilla/websocket"
@@ -11,6 +12,8 @@ import (
 	"reichard.io/conduit/types"
 )
 
+type ConnBuilder func() (conn io.ReadWriteCloser, err error)
+
 func NewServerTunnel(name string, wsConn *websocket.Conn) *Tunnel {
 	return &Tunnel{
 		name:    name,
@@ -19,22 +22,40 @@ func NewServerTunnel(name string, wsConn *websocket.Conn) *Tunnel {
 	}
 }
 
-func NewClientTunnel(name, target string, wsConn *websocket.Conn) *Tunnel {
-	return &Tunnel{
-		name:    name,
-		wsConn:  wsConn,
-		streams: make(map[string]io.ReadWriteCloser),
-		connBuilder: func() (io.ReadWriteCloser, error) {
-			return net.Dial("tcp", target)
-		},
+func NewClientTunnel(name, target string, wsConn *websocket.Conn) (*Tunnel, error) {
+	targetURL, err := url.Parse(target)
+	if err != nil {
+		return nil, err
 	}
+
+	var connBuilder ConnBuilder
+	switch targetURL.Scheme {
+	case "http", "https":
+		log.Infof("creating HTTP tunnel: %s -> %s", name, target)
+		connBuilder, err = HTTPConnectionBuilder(targetURL)
+		if err != nil {
+			return nil, err
+		}
+	default:
+		log.Infof("creating TCP tunnel: %s -> %s", name, target)
+		connBuilder = func() (conn io.ReadWriteCloser, err error) {
+			return net.Dial("tcp", target)
+		}
+	}
+
+	return &Tunnel{
+		name:        name,
+		wsConn:      wsConn,
+		streams:     make(map[string]io.ReadWriteCloser),
+		connBuilder: connBuilder,
+	}, nil
 }
 
 type Tunnel struct {
 	name        string
 	wsConn      *websocket.Conn
 	streams     map[string]io.ReadWriteCloser
-	connBuilder func() (io.ReadWriteCloser, error)
+	connBuilder ConnBuilder
 
 	wsMu, streamsMu sync.Mutex
 }