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  # Heavily based on  
 34  # http://twistedmatrix.com/trac/browser/sandbox/exarkun/copyover/server.py 
 35  # and client.py 
 36  # Thanks for the inspiration! 
 37   
 38  # Since we're doing this over a stream socket, our file descriptor messages 
 39  # aren't guaranteed to be received alone; they could arrive along with some 
 40  # unrelated data. 
 41  # So, we prefix the message with a 16 byte magic signature, and a length, 
 42  # and if we receive file descriptors decode based on this. 
 43  MAGIC_SIGNATURE = "\xfd\xfc\x8e\x7f\x07\x47\xb9\xea" \ 
 44                    "\xa1\x75\xee\xd8\xdc\x36\xc8\xa3" 
 45   
46 -class FDServer(unix.Server):
47 - def sendFileDescriptor(self, fileno, data=""):
48 message = struct.pack("@16sI", MAGIC_SIGNATURE, len(data)) + data 49 return fdpass.writefds(self.fileno(), [fileno], message)
50
51 -class FDPort(unix.Port):
52 transport = FDServer
53
54 -class FDClient(unix.Client): #, log.Loggable):
55
56 - def doRead(self):
57 if not self.connected: 58 return 59 try: 60 (fds, message) = fdpass.readfds(self.fileno(), 64 * 1024) 61 except socket.error, se: 62 if se.args[0] == errno.EWOULDBLOCK: 63 return 64 else: 65 return main.CONNECTION_LOST 66 else: 67 if not message: 68 return main.CONNECTION_DONE 69 70 if len(fds) > 0: 71 # Look for our magic cookie in (possibly) the midst of other 72 # data. Pass surrounding chunks, if any, onto dataReceived(), 73 # which (undocumentedly) must return None unless a failure 74 # occurred. 75 # Pass the actual FDs and their message to 76 # fileDescriptorsReceived() 77 offset = message.find(MAGIC_SIGNATURE) 78 if offset < 0: 79 # Old servers did not send this; be hopeful that this 80 # doesn't have bits of other protocol (i.e. PB) mixed up 81 # in it. 82 return self.protocol.fileDescriptorsReceived(fds, message) 83 elif offset > 0: 84 ret = self.protocol.dataReceived(message[0:offset]) 85 if ret: 86 return ret 87 88 msglen = struct.unpack("@I", message[offset+16:offset+20])[0] 89 offset += 20 90 ret = self.protocol.fileDescriptorsReceived(fds, 91 message[offset:offset+msglen]) 92 if ret: 93 return ret 94 95 if offset+msglen < len(message): 96 return self.protocol.dataReceived(message[offset+msglen:]) 97 return ret 98 else: 99 # self.debug("No FDs, passing to dataReceived") 100 return self.protocol.dataReceived(message)
101
102 -class FDConnector(unix.Connector):
103 - def _makeTransport(self):
104 return FDClient(self.address, self, self.reactor)
105
106 -class FDPassingBroker(pb.Broker, log.Loggable):
107 """ 108 A pb.Broker subclass that handles FDs being passed to it (with associated 109 data) over the same connection as the normal PB data stream. 110 When an FD is seen, it creates new protocol objects for them from the 111 childFactory attribute. 112 """ 113 # FIXME: looks like we can only use our own subclasses that take 114 # three __init__ args
115 - def __init__(self, childFactory, connectionClass, **kwargs):
116 """ 117 @param connectionClass: a subclass of L{twisted.internet.tcp.Connection} 118 """ 119 pb.Broker.__init__(self, **kwargs) 120 121 self.childFactory = childFactory 122 self._connectionClass = connectionClass
123 124 # This is the complex bit. If our underlying transport receives a file 125 # descriptor, this gets called - along with the data we got with the FD. 126 # We create an appropriate protocol object, and attach it to the reactor.
127 - def fileDescriptorsReceived(self, fds, message):
128 if len(fds) == 1: 129 fd = fds[0] 130 131 # Note that we hardcode IPv4 here! 132 sock = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM) 133 134 self.debug("Received FD %d->%d" % (fd, sock.fileno())) 135 136 # Undocumentedly (other than a comment in 137 # Python/Modules/socketmodule.c), socket.fromfd() calls dup() on 138 # the passed FD before it actually wraps it in a socket object. 139 # So, we need to close the FD that we originally had... 140 os.close(fd) 141 142 peeraddr = sock.getpeername() 143 144 # Based on bits in tcp.Port.doRead() 145 protocol = self.childFactory.buildProtocol( 146 address._ServerFactoryIPv4Address('TCP', 147 peeraddr[0], peeraddr[1])) 148 149 self._connectionClass(sock, protocol, message) 150 else: 151 self.warning("Unexpected: FD-passing message with len(fds) != 1")
152
153 -class PassableServerConnection(tcp.Server):
154 """ 155 A subclass of tcp.Server that permits passing the FDs used to other 156 processes (by just calling close(2) rather than shutdown(2) on them) 157 """ 158
159 - def __init__(self, sock, protocol, client, server, sessionno):
160 tcp.Server.__init__(self, sock, protocol, client, server, sessionno) 161 self.keepSocketAlive = False
162
163 - def _closeSocket(self):
164 # We override this (from tcp._SocketCloser) so that we can close sockets 165 # properly in the normal case, but once we've passed our socket on via 166 # the FD-channel, we just close() it (not calling shutdown() which will 167 # close the TCP channel without closing the FD itself) 168 if self.keepSocketAlive: 169 try: 170 self.socket.close() 171 except socket.error: 172 pass 173 else: 174 tcp.Server._closeSocket(self)
175
176 -class PassableServerPort(tcp.Port):
177 transport = PassableServerConnection
178