add X11 socket/port probe

2025-08-02 22:23:57 -04:00
parent 6b87c9e688
commit 1795e91387
4 changed files with 422 additions and 279 deletions
--- a/x11probe/probe.go
+++ b/x11probe/probe.go
@@ -0,0 +1,125 @@
+package x11probe
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"strings"
+	"time"
+)
+
+type ConnType int
+
+const (
+	Unix ConnType = iota
+	TCP
+)
+
+// X11Status represents the result of probing an X11 socket.
+type X11Status int
+
+const (
+	X11Dead X11Status = iota
+	X11Live
+	X11AuthRequired
+)
+
+func ProbeX11Socket(connType ConnType, target string, timeout time.Duration) (X11Status, error) {
+	var (
+		conn net.Conn
+		err  error
+	)
+
+	switch connType {
+	case Unix:
+		conn, err = net.DialTimeout("unix", target, timeout)
+		if err != nil {
+			return X11Dead, fmt.Errorf("unix dial failed: %w", err)
+		}
+	case TCP:
+		addr := parseTCPAddress(target)
+		conn, err = net.DialTimeout("tcp", addr, timeout)
+		if err != nil {
+			return X11Dead, fmt.Errorf("TCP dial failed: %w", err)
+		}
+	}
+
+	defer conn.Close()
+	log.Printf("Successfully connected to %s", target)
+
+	if err := performHandshake(conn); err != nil {
+		return X11Dead, err
+	}
+
+	status, err := readResponse(conn, timeout)
+	if err != nil {
+		return X11Dead, err
+	}
+
+	return status, nil
+}
+
+func parseTCPAddress(target string) string {
+	parts := strings.SplitN(target, ":", 2)
+
+	ipPart := parts[0]
+	portPart := "0"
+
+	if len(parts) == 2 && portPart != "" {
+		portPart = parts[1]
+	}
+
+	return fmt.Sprintf("%s:%s", ipPart, portPart)
+}
+
+func performHandshake(conn net.Conn) error {
+	// Minimal valid handshake with correct padding
+	handshake := []byte{
+		'l', 0, // Byte order
+		0, 11, 0, 0, // Protocol major/minor
+		0, 0, // Auth name length
+		0, 0, // Auth data length
+		0, 0, 0, 0, // Padding
+	}
+
+	if _, err := conn.Write(handshake); err != nil {
+		return fmt.Errorf("write failed: %w", err)
+	}
+	return nil
+}
+
+func readResponse(conn net.Conn, timeout time.Duration) (X11Status, error) {
+	buf := make([]byte, 1)
+
+	deadline := time.Now().Add(timeout)
+	if err := conn.SetReadDeadline(deadline); err != nil {
+		return X11Dead, fmt.Errorf("SetReadDeadline failed: %w", err)
+	}
+
+	n, err := conn.Read(buf)
+	if err != nil {
+		if err == io.EOF {
+			return X11AuthRequired, nil
+		}
+		return X11Dead, fmt.Errorf("read failed: %w", err)
+	}
+
+	if n == 0 {
+		return X11Dead, fmt.Errorf("read returned 0 bytes")
+	}
+
+	switch buf[0] {
+	case 0x01:
+		return X11Live, nil
+	case 0x02:
+		return X11AuthRequired, nil
+	case 0x00:
+		fmt.Printf("X11 handshake rejected (value %x)\n", buf[0])
+		return X11AuthRequired, nil
+	default:
+		fmt.Printf("unexpected value %x\n", buf[0])
+		return X11Dead, nil
+	}
+
+}