1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20 """\
21 Python Gevent based port forwarding server (openssh -L option) for the
22 proxying of graphical X2go elements.
23
24 """
25 __NAME__ = "x2gofwtunnel-pylib"
26
27
28 import os, sys, copy
29
30
31 import gevent
32 from gevent import select, socket
33 from gevent.server import StreamServer
34
35
36 import log
37 from defaults import X2GOCLIENT_OS as _X2GOCLIENT_OS
38 import x2go_exceptions
39
41 """\
42 L{X2goFwServer} implements a gevent's StreamServer based Paramiko/SSH port
43 forwarding server.
44
45 An L{X2goFwServer} class object is used to tunnel graphical trafic
46 through an external proxy command launched by a C{X2goProxy*} backend.
47
48 """
49 - def __init__ (self, listener, remote_host, remote_port, ssh_transport, session_instance=None, logger=None, loglevel=log.loglevel_DEFAULT,):
50 """\
51 @param listener: listen on TCP/IP socket C{(<IP>, <Port>)}
52 @type listener: C{tuple}
53 @param remote_host: hostname or IP of remote host (in case of X2go mostly 127.0.0.1)
54 @type remote_host: C{str}
55 @param remote_port: port of remote host
56 @type remote_port: C{int}
57 @param ssh_transport: a valid Paramiko/SSH transport object
58 @type ssh_transport: C{instance}
59 @param logger: you can pass an L{X2goLogger} object to the
60 L{X2goFwServer} constructor
61 @type logger: C{instance}
62 @param loglevel: if no L{X2goLogger} object has been supplied a new one will be
63 constructed with the given loglevel
64 @type loglevel: C{int}
65
66 """
67 if logger is None:
68 self.logger = log.X2goLogger(loglevel=loglevel)
69 else:
70 self.logger = copy.deepcopy(logger)
71 self.logger.tag = __NAME__
72
73 self.chan = None
74 self.is_active = False
75 self.keepalive = False
76 self.chain_host = remote_host
77 self.chain_port = remote_port
78 self.ssh_transport = ssh_transport
79 self.session_instance = session_instance
80
81 self.fw_socket = None
82
83 StreamServer.__init__(self, listener, self.x2go_forward_tunnel_handle)
84
86 """\
87 Handle for SSH/Paramiko forwarding tunnel.
88
89 @param fw_socket: local end of the forwarding tunnel
90 @type fw_socket: C{instance}
91 @param address: unused/ignored
92 @type address: C{tuple}
93
94 """
95 self.fw_socket = fw_socket
96
97
98 self.fw_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
99
100 _success = False
101 _count = 0
102 _maxwait = 20
103
104 while not _success and _count < _maxwait:
105
106
107 if self.session_instance:
108 if not self.session_instance.is_connected():
109 break
110
111 _count += 1
112 try:
113 self.chan = self.ssh_transport.open_channel('direct-tcpip',
114 (self.chain_host, self.chain_port),
115 self.fw_socket.getpeername())
116 chan_peername = self.chan.getpeername()
117 _success = True
118 except Exception, e:
119 self.logger('incoming request to %s:%d failed on attempt %d of %d: %s' % (self.chain_host,
120 self.chain_port,
121 _count,
122 _maxwait,
123 repr(e)),
124 loglevel=log.loglevel_WARN)
125 gevent.sleep(.4)
126
127
128 if not _success:
129 self.logger('incoming request to %s:%d failed after %d attempts' % (self.chain_host,
130 self.chain_port,
131 _count),
132 loglevel=log.loglevel_ERROR)
133 else:
134
135 self.is_active = True
136
137 if self.chan is None:
138 self.logger('incoming request to [%s]:%d was rejected by the SSH server.' %
139 (self.chain_host, self.chain_port), loglevel=log.loglevel_ERROR)
140 if self.session_instance:
141 self.session_instance.HOOK_forwarding_tunnel_setup_failed(chain_host=self.chain_host, chain_port=self.chain_port)
142 return
143 else:
144 self.logger('connected! Tunnel open %r -> %r -> %r' % (self.fw_socket.getpeername(),
145 chan_peername, (self.chain_host, self.chain_port)),
146 loglevel=log.loglevel_INFO)
147 self.keepalive = True
148 try:
149 while self.keepalive:
150 r, w, x = select.select([self.fw_socket, self.chan], [], [])
151 if fw_socket in r:
152 data = fw_socket.recv(1024)
153 if len(data) == 0:
154 break
155 self.chan.send(data)
156 if self.chan in r:
157 data = self.chan.recv(1024)
158 if len(data) == 0:
159 break
160 fw_socket.send(data)
161 self.close_channel()
162 self.close_socket()
163 except socket.error:
164 pass
165
166 self.is_active = False
167 self.logger('Tunnel closed from %r' % (chan_peername,),
168 loglevel=log.loglevel_INFO)
169
171 """\
172 Close an open channel again.
173
174 """
175
176 if self.chan is not None:
177 try:
178 if _X2GOCLIENT_OS != 'Windows':
179 self.chan.close()
180 self.chan = None
181 except EOFError:
182 pass
183
185 """\
186 Close the forwarding tunnel's socket again.
187
188 """
189 _success = False
190 _count = 0
191 _maxwait = 20
192
193
194 while not _success and _count < _maxwait:
195 _count += 1
196 try:
197 self.close_channel()
198 if self.fw_socket is not None:
199 self.fw_socket.close()
200 _success = True
201 except socket.error:
202 gevent.sleep(.2)
203 self.logger('could not close fw_tunnel socket, try again (%s of %s)' % (_count, _maxwait), loglevel=log.loglevel_WARN)
204
205 if _count >= _maxwait:
206 self.logger('forwarding tunnel to [%s]:%d could not be closed properly' % (self.chain_host, self.chain_port), loglevel=log.loglevel_WARN)
207
209 """\
210 Stop the forwarding tunnel.
211
212 """
213 self.close_socket()
214 StreamServer.stop(self)
215
216
217 -def start_forward_tunnel(local_host='127.0.0.1', local_port=22022,
218 remote_host='127.0.0.1', remote_port=22,
219 ssh_transport=None,
220 session_instance=None,
221 logger=None, ):
222 """\
223 Setup up a Paramiko/SSH port forwarding tunnel (like openssh -L option).
224
225 The tunnel is used to transport X2go graphics data through a proxy application like nxproxy.
226
227 @param local_host: local starting point of the forwarding tunnel
228 @type local_host: C{int}
229 @param local_port: listen port of the local starting point
230 @type local_port: C{int}
231 @param remote_host: from the endpoint of the tunnel, connect to host C{<remote_host>}...
232 @type remote_host: C{str}
233 @param remote_port: ... on port C{<remote_port>}
234 @type remote_port: C{int}
235 @param ssh_transport: the Paramiko/SSH transport (i.e. the X2go sessions Paramiko/SSH transport object)
236 @type ssh_transport: C{instance}
237 @param session_instance: the L{X2goSession} instance that initiates this tunnel
238 @type session_instance: C{instance}
239 @param logger: an X2goLogger object
240 @type logger: C{instance}
241
242 @return: returns an L{X2goFwServer} instance
243 @rtype: C{instance}
244
245 """
246 try:
247 fw_server = X2goFwServer(listener=(local_host, local_port),
248 remote_host=remote_host, remote_port=remote_port,
249 ssh_transport=ssh_transport, session_instance=session_instance,
250 logger=logger,
251 )
252 try:
253 fw_server.start()
254 return fw_server
255 except socket.error:
256 pass
257 except x2go_exceptions.X2goFwTunnelException:
258 pass
259
260 return None
261
262
264 """\
265 Tear down a given Paramiko/SSH port forwarding tunnel.
266
267 @param fw_server: an L{X2goFwServer} instance as returned by the L{start_forward_tunnel()} function
268 @type fw_server: C{instance}
269
270 """
271 if fw_server is not None:
272 fw_server.keepalive = False
273 gevent.sleep(.5)
274 fw_server.stop()
275
276
277 if __name__ == '__main__':
278 pass
279