From 15557251174130ef477fcb1c1a9536ae1834dc21 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Mon, 26 Oct 2015 15:36:06 +0530
Subject: [PATCH] Handle control frames that arrive in multiple TCP fragments

---
 src/calibre/srv/web_socket.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/calibre/srv/web_socket.py b/src/calibre/srv/web_socket.py
index d37ccba535..471541b4fa 100644
--- a/src/calibre/srv/web_socket.py
+++ b/src/calibre/srv/web_socket.py
@@ -63,6 +63,7 @@ class ReadFrame(object):  # {{{
 
     def reset(self):
         self.state = self.read_header0
+        self.control_buf = []
 
     def __call__(self, conn):
         return self.state(conn)
@@ -80,11 +81,12 @@ class ReadFrame(object):  # {{{
 
         self.opcode = b & 0b1111
         self.state = self.read_header1
+        self.is_control = self.opcode in CONTROL_CODES
         if self.opcode not in ALL_CODES:
             conn.log.error('Unknown OPCODE from client: %r' % self.opcode)
             conn.websocket_close(PROTOCOL_ERROR, 'Unknown OPCODE: %r' % self.opcode)
             return
-        if not self.fin and self.opcode in CONTROL_CODES:
+        if not self.fin and self.is_control:
             conn.log.error('Fragmented control frame from client')
             conn.websocket_close(PROTOCOL_ERROR, 'Fragmented control frame')
             return
@@ -101,7 +103,7 @@ class ReadFrame(object):  # {{{
             self.reset()
             return
         self.payload_length = b & 0b01111111
-        if self.opcode in CONTROL_CODES and self.payload_length > 125:
+        if self.is_control and self.payload_length > 125:
             conn.log.error('Too large control frame from client')
             conn.websocket_close(PROTOCOL_ERROR, 'Control frame too large')
             self.reset()
@@ -155,6 +157,12 @@ class ReadFrame(object):  # {{{
             data = b''
         self.pos += len(data)
         frame_finished = self.pos >= self.payload_length
+        if self.is_control:
+            self.control_buf.append(data)
+            if frame_finished:
+                data = b''.join(self.control_buf)
+            else:
+                return
         conn.ws_data_received(data, self.opcode, self.frame_starting, frame_finished, self.fin)
         self.frame_starting = False
         if frame_finished: