initial version of the basic x11 proxy

auth.go

@@ -0,0 +1,116 @@
+package main
+
+import (
+    "fmt"
+    "os"
+    "os/exec"
+    "path"
+    "strconv"
+    "strings"
+	"net"
+)
+
+func resolveDisplay(display string) (ConnType, string) {
+    var dispNum int
+    var err error
+
+    if strings.HasPrefix(display, ":") {
+        dispNum, err = strconv.Atoi(strings.Split(display[1:], ".")[0])
+    } else {
+        parts := strings.Split(display, ":")
+        dispNum, err = strconv.Atoi(strings.Split(parts[1], ".")[0])
+    }
+    if err != nil {
+        dispNum = 0
+    }
+
+    unixPath := path.Join("/tmp/.X11-unix", fmt.Sprintf("X%d", dispNum))
+    if _, err := os.Stat(unixPath); err == nil {
+        return Unix, unixPath
+    }
+
+    tcpAddr := fmt.Sprintf("127.0.0.1:%d", 6000+dispNum)
+    conn, err := net.Dial("tcp", tcpAddr)
+    if err == nil {
+        conn.Close()
+        return TCP, tcpAddr
+    }
+
+    return Unix, unixPath
+}
+
+func getXAuthCookie(display string) ([]byte, error) {
+    out, err := exec.Command("xauth", "list").Output()
+    if err != nil {
+        return nil, err
+    }
+
+    var dispNum string
+    if strings.HasPrefix(display, ":") {
+        dispNum = strings.Split(display[1:], ".")[0]
+    } else {
+        parts := strings.Split(display, ":")
+        dispNum = strings.Split(parts[1], ".")[0]
+    }
+
+    lines := strings.Split(string(out), "\n")
+    for _, line := range lines {
+        fields := strings.Fields(line)
+        if len(fields) >= 3 && fields[1] == "MIT-MAGIC-COOKIE-1" {
+            entry := fields[0]
+            if strings.Contains(entry, ":"+dispNum) {
+                fmt.Printf("Using XAuth cookie from entry: %s\n", entry)
+                return parseHexCookie(fields[2]), nil
+            }
+        }
+    }
+
+    return nil, fmt.Errorf("no matching cookie found for display %s", display)
+}
+
+
+func parseHexCookie(hexStr string) []byte {
+    var cookie []byte
+    for i := 0; i < len(hexStr); i += 2 {
+        var val byte
+        fmt.Sscanf(hexStr[i:i+2], "%02x", &val)
+        cookie = append(cookie, val)
+    }
+    return cookie
+}
+
+func PatchAuth(data []byte, cookie []byte) []byte {
+    isLittleEndian := data[0] == 'l'
+
+    var authProtoLen, authDataLen int
+    if isLittleEndian {
+        authProtoLen = int(data[7])<<8 | int(data[6])
+        authDataLen = int(data[9])<<8 | int(data[8])
+    } else {
+        authProtoLen = int(data[6])<<8 | int(data[7])
+        authDataLen = int(data[8])<<8 | int(data[9])
+    }
+
+    headerLen := 12
+    authProtoPad := (authProtoLen + 3) & ^3
+    authDataPad := (authDataLen + 3) & ^3
+    authDataStart := headerLen + authProtoPad
+
+    // Replace cookie and update length
+    patched := make([]byte, headerLen+authProtoPad+authDataPad)
+    copy(patched, data[:headerLen+authProtoPad])
+    copy(patched[authDataStart:], cookie)
+
+    // Update authDataLen to match cookie length
+    cookieLen := len(cookie)
+    if isLittleEndian {
+        patched[8] = byte(cookieLen)
+        patched[9] = byte(cookieLen >> 8)
+    } else {
+        patched[8] = byte(cookieLen >> 8)
+        patched[9] = byte(cookieLen)
+    }
+
+    return patched
+}
+