feat: TProxy

app/internal/tproxy/tcp_linux.go

@@ -0,0 +1,69 @@
+package tproxy
+
+import (
+	"io"
+	"net"
+
+	"github.com/apernet/go-tproxy"
+	"github.com/apernet/hysteria/core/client"
+)
+
+type TCPTProxy struct {
+	HyClient    client.Client
+	EventLogger TCPEventLogger
+}
+
+type TCPEventLogger interface {
+	Connect(addr, reqAddr net.Addr)
+	Error(addr, reqAddr net.Addr, err error)
+}
+
+func (r *TCPTProxy) ListenAndServe(laddr *net.TCPAddr) error {
+	listener, err := tproxy.ListenTCP("tcp", laddr)
+	if err != nil {
+		return err
+	}
+	defer listener.Close()
+	for {
+		c, err := listener.Accept()
+		if err != nil {
+			return err
+		}
+		go r.handle(c)
+	}
+}
+
+func (r *TCPTProxy) handle(conn net.Conn) {
+	defer conn.Close()
+	// In TProxy mode, we are masquerading as the remote server.
+	// So LocalAddr is actually the target the user is trying to connect to,
+	// and RemoteAddr is the local address.
+	if r.EventLogger != nil {
+		r.EventLogger.Connect(conn.RemoteAddr(), conn.LocalAddr())
+	}
+	var closeErr error
+	defer func() {
+		if r.EventLogger != nil {
+			r.EventLogger.Error(conn.RemoteAddr(), conn.LocalAddr(), closeErr)
+		}
+	}()
+
+	rc, err := r.HyClient.TCP(conn.LocalAddr().String())
+	if err != nil {
+		closeErr = err
+		return
+	}
+	defer rc.Close()
+
+	// Start forwarding
+	copyErrChan := make(chan error, 2)
+	go func() {
+		_, copyErr := io.Copy(rc, conn)
+		copyErrChan <- copyErr
+	}()
+	go func() {
+		_, copyErr := io.Copy(conn, rc)
+		copyErrChan <- copyErr
+	}()
+	closeErr = <-copyErrChan
+}