Package flumotion :: Package twisted :: Module fdserver
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Source Code for Module flumotion.twisted.fdserver

  1  # -*- Mode: Python -*- 
  2  # vi:si:et:sw=4:sts=4:ts=4 
  3  # 
  4  # Flumotion - a streaming media server 
  5  # Copyright (C) 2004,2005,2006,2007 Fluendo, S.L. (www.fluendo.com). 
  6  # All rights reserved. 
  7   
  8  # This file may be distributed and/or modified under the terms of 
  9  # the GNU General Public License version 2 as published by 
 10  # the Free Software Foundation. 
 11  # This file is distributed without any warranty; without even the implied 
 12  # warranty of merchantability or fitness for a particular purpose. 
 13  # See "LICENSE.GPL" in the source distribution for more information. 
 14   
 15  # Licensees having purchased or holding a valid Flumotion Advanced 
 16  # Streaming Server license may use this file in accordance with the 
 17  # Flumotion Advanced Streaming Server Commercial License Agreement. 
 18  # See "LICENSE.Flumotion" in the source distribution for more information. 
 19   
 20  # Headers in this file shall remain intact. 
 21   
 22  from flumotion.common import log 
 23  from flumotion.extern.fdpass import fdpass 
 24   
 25  from twisted.internet import unix, main, address, tcp 
 26  from twisted.spread import pb 
 27   
 28  import errno 
 29  import os 
 30  import socket 
 31  import struct 
 32   
 33  __version__ = "$Rev: 6125 $" 
 34   
 35   
 36  # Heavily based on 
 37  # http://twistedmatrix.com/trac/browser/sandbox/exarkun/copyover/server.py 
 38  # and client.py 
 39  # Thanks for the inspiration! 
 40   
 41  # Since we're doing this over a stream socket, our file descriptor messages 
 42  # aren't guaranteed to be received alone; they could arrive along with some 
 43  # unrelated data. 
 44  # So, we prefix the message with a 16 byte magic signature, and a length, 
 45  # and if we receive file descriptors decode based on this. 
 46  # 
 47  # map() instead of a string to workaround gettext encoding problems. 
 48  # 
 49  MAGIC_SIGNATURE = ''.join(map(chr, [253, 252, 142, 127, 7, 71, 185, 234, 
 50                                      161, 117, 238, 216, 220, 54, 200, 163])) 
 51   
52 -class FDServer(unix.Server):
53 - def sendFileDescriptor(self, fileno, data=""):
54 message = struct.pack("@16sI", MAGIC_SIGNATURE, len(data)) + data 55 return fdpass.writefds(self.fileno(), [fileno], message)
56
57 -class FDPort(unix.Port):
58 transport = FDServer
59
60 -class FDClient(unix.Client): #, log.Loggable):
61
62 - def doRead(self):
63 if not self.connected: 64 return 65 try: 66 (fds, message) = fdpass.readfds(self.fileno(), 64 * 1024) 67 except socket.error, se: 68 if se.args[0] == errno.EWOULDBLOCK: 69 return 70 else: 71 return main.CONNECTION_LOST 72 else: 73 if not message: 74 return main.CONNECTION_DONE 75 76 if len(fds) > 0: 77 # Look for our magic cookie in (possibly) the midst of other 78 # data. Pass surrounding chunks, if any, onto dataReceived(), 79 # which (undocumentedly) must return None unless a failure 80 # occurred. 81 # Pass the actual FDs and their message to 82 # fileDescriptorsReceived() 83 offset = message.find(MAGIC_SIGNATURE) 84 if offset < 0: 85 # Old servers did not send this; be hopeful that this 86 # doesn't have bits of other protocol (i.e. PB) mixed up 87 # in it. 88 return self.protocol.fileDescriptorsReceived(fds, message) 89 elif offset > 0: 90 ret = self.protocol.dataReceived(message[0:offset]) 91 if ret: 92 return ret 93 94 msglen = struct.unpack("@I", message[offset+16:offset+20])[0] 95 offset += 20 96 ret = self.protocol.fileDescriptorsReceived(fds, 97 message[offset:offset+msglen]) 98 if ret: 99 return ret 100 101 if offset+msglen < len(message): 102 return self.protocol.dataReceived(message[offset+msglen:]) 103 return ret 104 else: 105 # self.debug("No FDs, passing to dataReceived") 106 return self.protocol.dataReceived(message)
107
108 -class FDConnector(unix.Connector):
109 - def _makeTransport(self):
110 return FDClient(self.address, self, self.reactor)
111
112 -class FDPassingBroker(pb.Broker, log.Loggable):
113 """ 114 A pb.Broker subclass that handles FDs being passed to it (with associated 115 data) over the same connection as the normal PB data stream. 116 When an FD is seen, it creates new protocol objects for them from the 117 childFactory attribute. 118 """ 119 # FIXME: looks like we can only use our own subclasses that take 120 # three __init__ args
121 - def __init__(self, childFactory, connectionClass, **kwargs):
122 """ 123 @param connectionClass: a subclass of L{twisted.internet.tcp.Connection} 124 """ 125 pb.Broker.__init__(self, **kwargs) 126 127 self.childFactory = childFactory 128 self._connectionClass = connectionClass
129 130 # This is the complex bit. If our underlying transport receives a file 131 # descriptor, this gets called - along with the data we got with the FD. 132 # We create an appropriate protocol object, and attach it to the reactor.
133 - def fileDescriptorsReceived(self, fds, message):
134 if len(fds) == 1: 135 fd = fds[0] 136 137 # Note that we hardcode IPv4 here! 138 sock = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM) 139 140 self.debug("Received FD %d->%d" % (fd, sock.fileno())) 141 142 # Undocumentedly (other than a comment in 143 # Python/Modules/socketmodule.c), socket.fromfd() calls dup() on 144 # the passed FD before it actually wraps it in a socket object. 145 # So, we need to close the FD that we originally had... 146 os.close(fd) 147 148 try: 149 peeraddr = sock.getpeername() 150 except socket.error: 151 self.info("Socket disconnected before being passed to client") 152 sock.close() 153 return 154 155 # Based on bits in tcp.Port.doRead() 156 addr = address._ServerFactoryIPv4Address('TCP', 157 peeraddr[0], peeraddr[1]) 158 protocol = self.childFactory.buildProtocol(addr) 159 160 self._connectionClass(sock, protocol, peeraddr, message) 161 else: 162 self.warning("Unexpected: FD-passing message with len(fds) != 1")
163
164 -class _SocketMaybeCloser(tcp._SocketCloser):
165 keepSocketAlive = False 166
167 - def _closeSocket(self):
168 # We override this (from tcp._SocketCloser) so that we can close sockets 169 # properly in the normal case, but once we've passed our socket on via 170 # the FD-channel, we just close() it (not calling shutdown() which will 171 # close the TCP channel without closing the FD itself) 172 if self.keepSocketAlive: 173 try: 174 self.socket.close() 175 except socket.error: 176 pass 177 else: 178 tcp.Server._closeSocket(self)
179
180 -class PassableServerConnection(_SocketMaybeCloser, tcp.Server):
181 """ 182 A subclass of tcp.Server that permits passing the FDs used to other 183 processes (by just calling close(2) rather than shutdown(2) on them) 184 """ 185 pass
186
187 -class PassableServerPort(tcp.Port):
188 transport = PassableServerConnection
189