Fix auth for remote hosts and handle different auth families

- Use the remote address to find the auth cookie instead of the local
  hostname
- Read family type as big endian in Xauthority file
- Don't upgrade 127.0.0.1 TCP connections to unix domain socket (libX11
  and xcb don't do this)
- Don't error if no auth cookie is found; continue without auth

lib/auth.js

@@ -1,4 +1,5 @@
-// TODO: http://en.wikipedia.org/wiki/X_Window_authorization
+// TODO: differentiate between auth types (i.e., MIT-MAGIC-COOKIE-1 and XDM-AUTHORIZATION-1)
+// and choose the best based on the algorithm in libXau's XauGetBestAuthByAddr
 
 var fs = require('fs');
 var Buffer = require('buffer').Buffer;
@@ -15,7 +16,7 @@ var typeToName = {
       1: 'DECnet',
       2: 'Chaos',
       5: 'ServerInterpreted',
-      6: 'InternetV6'
+      6: 'Internet6'
 };
 
 function parseXauth( buf )
@@ -27,7 +28,7 @@ function parseXauth( buf )
     while (offset < buf.length)
     {
         var cookie = {};
-        cookie.type = buf.readUInt16LE(offset);
+        cookie.type = buf.readUInt16BE(offset);
         if (!typeToName[cookie.type]) {
             console.warn('Unknown address type');
         }
@@ -73,8 +74,16 @@ function readXauthority(cb) {
   });
 }
 
-module.exports = function( display, host, cb )
+module.exports = function( display, host, socketFamily, cb )
 {
+  var family;
+  if (socketFamily === 'IPv4') {
+    family = 0; // Internet
+  } else if (socketFamily === 'IPv6') {
+    family = 6; // Internet6
+  } else {
+    family = 256; // Local
+  }
   readXauthority(function(err, data) {
     if(err) return cb(err);
 
@@ -84,15 +93,18 @@ module.exports = function( display, host, cb )
         authData: ''
       });
     }
-
     var auth = parseXauth(data);
     for (var cookieNum in auth)
     {
       var cookie = auth[cookieNum];
-      if ((typeToName[cookie.family] === 'Wild' || cookie.address === host) &&
+      if ((typeToName[cookie.family] === 'Wild' || (cookie.type === family && cookie.address === host)) &&
           (cookie.display.length === 0 || cookie.display === display))
         return cb( null, cookie );
     }
-    cb(new Error('No auth cookie matching display=' + display + ' and  host=' + host));
+    // If no cookie is found, proceed without authentication
+    cb(null, {
+      authName: '',
+      authData: ''
+    });
   });
 };

lib/handshake.js

@@ -189,9 +189,9 @@ function getByteOrder() {
     }
 }
 
-function writeClientHello(stream, displayNum, authHost)
+function writeClientHello(stream, displayNum, authHost, authFamily)
 {
-    getAuthString( displayNum, authHost, function( err, cookie ) {
+    getAuthString( displayNum, authHost, authFamily, function( err, cookie ) {
         if (err) {
             throw err;
         }

lib/xcore.js

@@ -31,7 +31,6 @@ function XClient(displayNum, screenNum, options)
 
     this.displayNum = displayNum;
     this.screenNum = screenNum;
-    this.authHost = os.hostname();
 }
 util.inherits(XClient, EventEmitter);
 
@@ -39,6 +38,13 @@ XClient.prototype.init = function(stream)
 {
     this.stream = stream;
 
+    this.authHost = stream.remoteAddress;
+    this.authFamily = stream.remoteFamily;
+    if (!this.authHost || this.authHost === '127.0.0.1' || this.authHost === '::1') {
+      this.authHost = os.hostname();
+      this.authFamily = null;
+    }
+
     var pack_stream = new PackStream();
 
     // data received from stream is dispached to
@@ -524,7 +530,7 @@ XClient.prototype.expectReplyHeader = function()
 XClient.prototype.startHandshake = function() {
     var client = this;
 
-    handshake.writeClientHello(this.pack_stream, this.displayNum, this.authHost);
+    handshake.writeClientHello(this.pack_stream, this.displayNum, this.authHost, this.authFamily);
     handshake.readServerHello(this.pack_stream, function(display)
     {
         // TODO: readServerHello can set error state in display
@@ -560,8 +566,6 @@ module.exports.createClient = function(options, initCb)
        throw new Error("Cannot parse display");
 
     var host = displayMatch[1];
-    if (!host)
-        host = '127.0.0.1';
 
     var displayNum = displayMatch[2];
     if (!displayNum)
@@ -586,10 +590,9 @@ module.exports.createClient = function(options, initCb)
             {
                 socketPath = display;
             }
-        } else if(host == '127.0.0.1') //TODO check if it's consistent with xlib (DISPLAY=127.0.0.1:0 -> local unix socket or port 6000?)
+        } else if(!host)
             socketPath = '/tmp/.X11-unix/X' + displayNum;
     }
-    //socketPath = '/tmp/.X11-unix/X' + displayNum;
     var client = new XClient(displayNum, screenNum, options);
 
     var connectStream = function() {