http: Allow WebSocket requests from other hosts

This makes Tornado 4.0 behavior consistent with previous Tornado versions.

Fixes #788

docs/changelog.rst

@@ -4,6 +4,18 @@ Changelog
 
 This changelog is used to track all major changes to Mopidy.
 
+
+v0.19.2 (UNRELEASED)
+====================
+
+Bug fix release.
+
+**HTTP**
+
+- When using Tornado 4.0, allow WebSocket requests from other hosts. (Fixes:
+  :issue:`788`)
+
+
 v0.19.1 (2014-07-23)
 ====================
 

mopidy/http/handlers.py

@@ -112,6 +112,11 @@ class WebSocketHandler(tornado.websocket.WebSocketHandler):
             logger.error('WebSocket request error: %s', e)
             self.close()
 
+    def check_origin(self, origin):
+        # Allow cross-origin WebSocket connections, like Tornado before 4.0
+        # defaulted to.
+        return True
+
 
 def set_mopidy_headers(request_handler):
     request_handler.set_header('Cache-Control', 'no-cache')