Initial CL for Downloads resumption.

net/tools/testserver/testserver.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This is a simple HTTP/FTP/SYNC/TCP/UDP/ server used for testing Chrome.
 
 It supports several test URLs, as specified by the handlers in TestPageHandler.
 By default, it listens on an ephemeral port and sends the port number back to
 the originating process over a pipe. The originating process can specify an
@@ skipping 10 matching lines @@
 import hashlib
 import json
 import logging
 import minica
 import os
 import random
 import re
 import select
 import socket
 import SocketServer
+import struct
 import sys
 import threading
 import time
 import urllib
 import urlparse
 import zlib
 
 import echo_message
 import pyftpdlib.ftpserver
 import testserver_base
@@ skipping 425 matching lines @@
       self.SlowServerHandler,
       self.ChunkedServerHandler,
       self.ContentTypeHandler,
       self.NoContentHandler,
       self.ServerRedirectHandler,
       self.ClientRedirectHandler,
       self.MultipartHandler,
       self.MultipartSlowHandler,
       self.GetSSLSessionCacheHandler,
       self.CloseSocketHandler,
+      self.RangeResetHandler,
       self.DefaultResponseHandler]
     post_handlers = [
       self.EchoTitleHandler,
       self.EchoHandler,
       self.DeviceManagementHandler,
       self.PostOnlyFileHandler] + get_handlers
     put_handlers = [
       self.EchoTitleHandler,
       self.EchoHandler] + get_handlers
     head_handlers = [
@@ skipping 1129 matching lines @@
 
   def CloseSocketHandler(self):
     """Closes the socket without sending anything."""
 
     if not self._ShouldHandleRequest('/close-socket'):
       return False
 
     self.wfile.close()
     return True
 
+  def RangeResetHandler(self):
+    """Send data broken up by connection resets every N (default 4K) bytes.
+    Support range requests.  If the data requested doesn't straddle a reset
+    boundary, it will all be sent.  Used for testing resuming downloads."""
+
+    if not self._ShouldHandleRequest('/rangereset'):
+      return False
+
+    _, _, url_path, _, query, _ = urlparse.urlparse(self.path)
+
+    # Defaults
+    size = 8000
+    # Note that the rst is sent just before sending the rst_boundary byte.
+    rst_boundary = 4000
+    respond_to_range = True
+    hold_for_signal = False
+
+    # Parse the query
+    qdict = urlparse.parse_qs(query, True)
+    if 'size' in qdict:
+      size = int(qdict['size'])
+    if 'rst_boundary' in qdict:
+      rst_boundary = int(qdict['rst_boundary'])
+    if 'bounce_range' in qdict:
+      respond_to_range = False
+    if 'hold' in qdict:
+      hold_for_signal = True
+
+    first_byte = 0
+    last_byte = size - 1
+
+    # Does that define what we want to return, or do we need to apply
+    # a range?
+    range_response = False
+    range_header = self.headers.getheader('range')
+    if range_header and respond_to_range:
+      mo = re.match("bytes=(\d*)-(\d*)", range_header)
+      if mo.group(1):
+        first_byte = int(mo.group(1))
+      if mo.group(2):
+        last_byte = int(mo.group(2))
+      if last_byte > size - 1:
+        last_byte = size - 1
+      range_response = True
+      if last_byte < first_byte:
+        return False
+
+    # Set socket send buf high enough that we don't need to worry
+    # about asynchronous closes when sending RSTs.
+    self.connection.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF,
+                               16284)
+
+    if range_response:
+      self.send_response(206)
+      self.send_header('Content-Range',
+                       'bytes %d-%d/%d' % (first_byte, last_byte, size))
+    else:
+      self.send_response(200)
+    self.send_header('Content-Type', 'application/octet-stream')
+    self.send_header('Content-Length', last_byte - first_byte + 1)
+    self.end_headers()
+
+    if hold_for_signal:
+      # Hack alert/explanation: Without writing a single byte, the

[Paweł Hajdan Jr., 2013/01/10 23:50:22]

Please file a bug for this and put a TODO here.

[Randy Smith (Not in Mondays), 2013/01/11 19:28:34]

Done.

+      # self.server.handle_request() below hangs without processing
+      # new incoming requests.  Presumably this is due to a bug in
+      # BaseHTTPRequestHandler.
+      self.wfile.write('X')
+      first_byte = first_byte + 1
+      # handle requests until one of them clears this flag.
+      self.server.waitForDownload = True
+      while self.server.waitForDownload:
+        self.server.handle_request()
+
+    possible_rst = ((first_byte / rst_boundary) + 1) * rst_boundary
+    if possible_rst >= last_byte:
+      # No RST has been requested in this range, so we don't need to
+      # do anything fancy; just write the data and let the python
+      # infrastructure close the connection.
+      self.wfile.write('X' * (last_byte - first_byte + 1))
+      self.wfile.flush()
+      return True
+
+    # We're resetting the connection part way in; go to the RST
+    # boundary and then send an RST.
+    # WINDOWS WARNING: On windows, if the amount of data sent before the
+    # reset is > 4096, only 4096 bytes will make it across before the RST
+    # despite the flush.  This is hypothesized to be due to an underlying
+    # asynchronous sending implementation, which the 0 second linger
+    # forcibly terminates.  The amount of data pre-RST should be kept below
+    # 4096 for this reason.
+    self.wfile.write('X' * (possible_rst - first_byte))
+    self.wfile.flush()
+    l_onoff = 1  # Linger is active.
+    l_linger = 0  # Seconds to linger for.
+    self.connection.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER,
+                 struct.pack('ii', l_onoff, l_linger))
+
+    # Close all duplicates of the underlying socket to force the RST.
+    self.wfile.close()
+    self.rfile.close()
+    self.connection.close()
+
+    return True
+
   def DefaultResponseHandler(self):
     """This is the catch-all response handler for requests that aren't handled
     by one of the special handlers above.
     Note that we specify the content-length as without it the https connection
     is not closed properly (and the browser keeps expecting data)."""
 
     contents = "Default response given for path: " + self.path
     self.send_response(200)
     self.send_header('Content-Type', 'text/html')
     self.send_header('Content-Length', len(contents))
@@ skipping 808 matching lines @@
                                   'load multipe keys into the server. If the '
                                   'server has multiple keys, it will rotate '
                                   'through them in at each request a '
                                   'round-robin fashion. The server will '
                                   'generate a random key if none is specified '
                                   'on the command line.')
 
 
 if __name__ == '__main__':
   sys.exit(ServerRunner().main())