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# -*- test-case-name: twisted.conch.test.test_session -*-
# Copyright (c) 2001-2009 Twisted Matrix Laboratories.
# See LICENSE for details.
"""
This module contains the implementation of SSHSession, which (by default)
allows access to a shell and a python interpreter over SSH.
Maintainer: Paul Swartz
"""
import struct
import signal
import sys
import os
from twisted.internet import protocol
from twisted.python import log
from twisted.conch.interfaces import ISession
from twisted.conch.ssh import common, channel
class SSHSession(channel.SSHChannel):
name = 'session'
def __init__(self, *args, **kw):
channel.SSHChannel.__init__(self, *args, **kw)
self.buf = ''
self.client = None
self.session = None
def request_subsystem(self, data):
subsystem, ignored= common.getNS(data)
log.msg('asking for subsystem "%s"' % subsystem)
client = self.avatar.lookupSubsystem(subsystem, data)
if client:
pp = SSHSessionProcessProtocol(self)
proto = wrapProcessProtocol(pp)
client.makeConnection(proto)
pp.makeConnection(wrapProtocol(client))
self.client = pp
return 1
else:
log.msg('failed to get subsystem')
return 0
def request_shell(self, data):
log.msg('getting shell')
if not self.session:
self.session = ISession(self.avatar)
try:
pp = SSHSessionProcessProtocol(self)
self.session.openShell(pp)
except:
log.deferr()
return 0
else:
self.client = pp
return 1
def request_exec(self, data):
if not self.session:
self.session = ISession(self.avatar)
f,data = common.getNS(data)
log.msg('executing command "%s"' % f)
try:
pp = SSHSessionProcessProtocol(self)
self.session.execCommand(pp, f)
except:
log.deferr()
return 0
else:
self.client = pp
return 1
def request_pty_req(self, data):
if not self.session:
self.session = ISession(self.avatar)
term, windowSize, modes = parseRequest_pty_req(data)
log.msg('pty request: %s %s' % (term, windowSize))
try:
self.session.getPty(term, windowSize, modes)
except:
log.err()
return 0
else:
return 1
def request_window_change(self, data):
if not self.session:
self.session = ISession(self.avatar)
winSize = parseRequest_window_change(data)
try:
self.session.windowChanged(winSize)
except:
log.msg('error changing window size')
log.err()
return 0
else:
return 1
def dataReceived(self, data):
if not self.client:
#self.conn.sendClose(self)
self.buf += data
return
self.client.transport.write(data)
def extReceived(self, dataType, data):
if dataType == connection.EXTENDED_DATA_STDERR:
if self.client and hasattr(self.client.transport, 'writeErr'):
self.client.transport.writeErr(data)
else:
log.msg('weird extended data: %s'%dataType)
def eofReceived(self):
if self.session:
self.session.eofReceived()
elif self.client:
self.conn.sendClose(self)
def closed(self):
if self.session:
self.session.closed()
elif self.client:
self.client.transport.loseConnection()
#def closeReceived(self):
# self.loseConnection() # don't know what to do with this
def loseConnection(self):
if self.client:
self.client.transport.loseConnection()
channel.SSHChannel.loseConnection(self)
class _ProtocolWrapper(protocol.ProcessProtocol):
"""
This class wraps a L{Protocol} instance in a L{ProcessProtocol} instance.
"""
def __init__(self, proto):
self.proto = proto
def connectionMade(self): self.proto.connectionMade()
def outReceived(self, data): self.proto.dataReceived(data)
def processEnded(self, reason): self.proto.connectionLost(reason)
class _DummyTransport:
def __init__(self, proto):
self.proto = proto
def dataReceived(self, data):
self.proto.transport.write(data)
def write(self, data):
self.proto.dataReceived(data)
def writeSequence(self, seq):
self.write(''.join(seq))
def loseConnection(self):
self.proto.connectionLost(protocol.connectionDone)
def wrapProcessProtocol(inst):
if isinstance(inst, protocol.Protocol):
return _ProtocolWrapper(inst)
else:
return inst
def wrapProtocol(proto):
return _DummyTransport(proto)
# SUPPORTED_SIGNALS is a list of signals that every session channel is supposed
# to accept. See RFC 4254
SUPPORTED_SIGNALS = ["ABRT", "ALRM", "FPE", "HUP", "ILL", "INT", "KILL",
"PIPE", "QUIT", "SEGV", "TERM", "USR1", "USR2"]
class SSHSessionProcessProtocol(protocol.ProcessProtocol):
# once initialized, a dictionary mapping signal values to strings
# that follow RFC 4254.
_signalValuesToNames = None
def __init__(self, session):
self.session = session
self.lostOutOrErrFlag = False
def connectionMade(self):
if self.session.buf:
self.transport.write(self.session.buf)
self.session.buf = None
def outReceived(self, data):
self.session.write(data)
def errReceived(self, err):
self.session.writeExtended(connection.EXTENDED_DATA_STDERR, err)
def outConnectionLost(self):
"""
EOF should only be sent when both STDOUT and STDERR have been closed.
"""
if self.lostOutOrErrFlag:
self.session.conn.sendEOF(self.session)
else:
self.lostOutOrErrFlag = True
def errConnectionLost(self):
"""
See outConnectionLost().
"""
self.outConnectionLost()
def connectionLost(self, reason = None):
self.session.loseConnection()
def _getSignalName(self, signum):
"""
Get a signal name given a signal number.
"""
if self._signalValuesToNames is None:
self._signalValuesToNames = {}
# make sure that the POSIX ones are the defaults
for signame in SUPPORTED_SIGNALS:
signame = 'SIG' + signame
sigvalue = getattr(signal, signame, None)
if sigvalue is not None:
self._signalValuesToNames[sigvalue] = signame
for k, v in signal.__dict__.items():
# Check for platform specific signals, ignoring Python specific
# SIG_DFL and SIG_IGN
if k.startswith('SIG') and not k.startswith('SIG_'):
if v not in self._signalValuesToNames:
self._signalValuesToNames[v] = k + '@' + sys.platform
return self._signalValuesToNames[signum]
def processEnded(self, reason=None):
"""
When we are told the process ended, try to notify the other side about
how the process ended using the exit-signal or exit-status requests.
Also, close the channel.
"""
if reason is not None:
err = reason.value
if err.signal is not None:
signame = self._getSignalName(err.signal)
if (getattr(os, 'WCOREDUMP', None) is not None and
os.WCOREDUMP(err.status)):
log.msg('exitSignal: %s (core dumped)' % (signame,))
coreDumped = 1
else:
log.msg('exitSignal: %s' % (signame,))
coreDumped = 0
self.session.conn.sendRequest(self.session, 'exit-signal',
common.NS(signame[3:]) + chr(coreDumped) +
common.NS('') + common.NS(''))
elif err.exitCode is not None:
log.msg('exitCode: %r' % (err.exitCode,))
self.session.conn.sendRequest(self.session, 'exit-status',
struct.pack('>L', err.exitCode))
self.session.loseConnection()
# transport stuff (we are also a transport!)
def write(self, data):
self.session.write(data)
def writeSequence(self, seq):
self.session.write(''.join(seq))
def loseConnection(self):
self.session.loseConnection()
class SSHSessionClient(protocol.Protocol):
def dataReceived(self, data):
if self.transport:
self.transport.write(data)
# methods factored out to make live easier on server writers
def parseRequest_pty_req(data):
"""Parse the data from a pty-req request into usable data.
@returns: a tuple of (terminal type, (rows, cols, xpixel, ypixel), modes)
"""
term, rest = common.getNS(data)
cols, rows, xpixel, ypixel = struct.unpack('>4L', rest[: 16])
modes, ignored= common.getNS(rest[16:])
winSize = (rows, cols, xpixel, ypixel)
modes = [(ord(modes[i]), struct.unpack('>L', modes[i+1: i+5])[0]) for i in range(0, len(modes)-1, 5)]
return term, winSize, modes
def packRequest_pty_req(term, (rows, cols, xpixel, ypixel), modes):
"""Pack a pty-req request so that it is suitable for sending.
NOTE: modes must be packed before being sent here.
"""
termPacked = common.NS(term)
winSizePacked = struct.pack('>4L', cols, rows, xpixel, ypixel)
modesPacked = common.NS(modes) # depend on the client packing modes
return termPacked + winSizePacked + modesPacked
def parseRequest_window_change(data):
"""Parse the data from a window-change request into usuable data.
@returns: a tuple of (rows, cols, xpixel, ypixel)
"""
cols, rows, xpixel, ypixel = struct.unpack('>4L', data)
return rows, cols, xpixel, ypixel
def packRequest_window_change((rows, cols, xpixel, ypixel)):
"""Pack a window-change request so that it is suitable for sending.
"""
return struct.pack('>4L', cols, rows, xpixel, ypixel)
import connection
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