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|
## tls_nb.py
## based on transports_nb.py
##
## Copyright (C) 2003-2004 Alexey "Snake" Nezhdanov
## modified by Dimitur Kirov <dkirov@gmail.com>
## modified by Tomas Karasek <tom.to.the.k@gmail.com>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
import socket
from plugin import PlugIn
import sys
import os
import time
import traceback
import logging
log = logging.getLogger('gajim.c.x.tls_nb')
USE_PYOPENSSL = False
PYOPENSSL = 'PYOPENSSL'
PYSTDLIB = 'PYSTDLIB'
try:
#raise ImportError("Manually disabled PyOpenSSL")
import OpenSSL.SSL
import OpenSSL.crypto
USE_PYOPENSSL = True
log.info("PyOpenSSL loaded")
except ImportError:
log.debug("Import of PyOpenSSL failed:", exc_info=True)
# FIXME: Remove these prints before release, replace with a warning dialog.
print >> sys.stderr, "=" * 79
print >> sys.stderr, "PyOpenSSL not found, falling back to Python builtin SSL objects (insecure)."
print >> sys.stderr, "=" * 79
def gattr(obj, attr, default=None):
try:
return getattr(obj, attr)
except AttributeError:
return default
class SSLWrapper:
'''
Abstract SSLWrapper base class
'''
class Error(IOError):
''' Generic SSL Error Wrapper '''
def __init__(self, sock=None, exc=None, errno=None, strerror=None,
peer=None):
self.parent = IOError
errno = errno or gattr(exc, 'errno')
strerror = strerror or gattr(exc, 'strerror') or gattr(exc, 'args')
if not isinstance(strerror, basestring):
strerror = repr(strerror)
self.sock = sock
self.exc = exc
self.peer = peer
self.exc_name = None
self.exc_args = None
self.exc_str = None
self.exc_repr = None
if self.exc is not None:
self.exc_name = str(self.exc.__class__)
self.exc_args = gattr(self.exc, 'args')
self.exc_str = str(self.exc)
self.exc_repr = repr(self.exc)
if not errno:
try:
if isinstance(exc, OpenSSL.SSL.SysCallError):
if self.exc_args[0] > 0:
errno = self.exc_args[0]
strerror = self.exc_args[1]
except: pass
self.parent.__init__(self, errno, strerror)
if self.peer is None and sock is not None:
try:
ppeer = self.sock.getpeername()
if len(ppeer) == 2 and isinstance(ppeer[0], basestring) \
and isinstance(ppeer[1], int):
self.peer = ppeer
except:
pass
def __str__(self):
s = str(self.__class__)
if self.peer:
s += " for %s:%d" % self.peer
if self.errno is not None:
s += ": [Errno: %d]" % self.errno
if self.strerror:
s += " (%s)" % self.strerror
if self.exc_name:
s += ", Caused by %s" % self.exc_name
if self.exc_str:
if self.strerror:
s += "(%s)" % self.exc_str
else: s += "(%s)" % str(self.exc_args)
return s
def __init__(self, sslobj, sock=None):
self.sslobj = sslobj
self.sock = sock
log.debug("%s.__init__ called with %s", self.__class__, sslobj)
def recv(self, data, flags=None):
'''
Receive wrapper for SSL object
We can return None out of this function to signal that no data is
available right now. Better than an exception, which differs
depending on which SSL lib we're using. Unfortunately returning ''
can indicate that the socket has been closed, so to be sure, we avoid
this by returning None.
'''
raise NotImplementedError
def send(self, data, flags=None, now=False):
''' Send wrapper for SSL object '''
raise NotImplementedError
class PyOpenSSLWrapper(SSLWrapper):
'''Wrapper class for PyOpenSSL's recv() and send() methods'''
def __init__(self, *args):
self.parent = SSLWrapper
self.parent.__init__(self, *args)
def is_numtoolarge(self, e):
''' Magic methods don't need documentation '''
t = ('asn1 encoding routines', 'a2d_ASN1_OBJECT', 'first num too large')
return (isinstance(e.args, (list, tuple)) and len(e.args) == 1 and
isinstance(e.args[0], (list, tuple)) and len(e.args[0]) == 2 and
e.args[0][0] == e.args[0][1] == t)
def recv(self, bufsize, flags=None):
retval = None
try:
if flags is None:
retval = self.sslobj.recv(bufsize)
else:
retval = self.sslobj.recv(bufsize, flags)
except (OpenSSL.SSL.WantReadError, OpenSSL.SSL.WantWriteError), e:
log.debug("Recv: Want-error: " + repr(e))
except OpenSSL.SSL.SysCallError, e:
log.debug("Recv: Got OpenSSL.SSL.SysCallError: " + repr(e),
exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
except OpenSSL.SSL.Error, e:
if self.is_numtoolarge(e):
# warn, but ignore this exception
log.warning("Recv: OpenSSL: asn1enc: first num too large (ignored)")
else:
log.debug("Recv: Caught OpenSSL.SSL.Error:", exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return retval
def send(self, data, flags=None, now=False):
try:
if flags is None:
return self.sslobj.send(data)
else:
return self.sslobj.send(data, flags)
except (OpenSSL.SSL.WantReadError, OpenSSL.SSL.WantWriteError), e:
#log.debug("Send: " + repr(e))
time.sleep(0.1) # prevent 100% CPU usage
except OpenSSL.SSL.SysCallError, e:
log.error("Send: Got OpenSSL.SSL.SysCallError: " + repr(e),
exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
except OpenSSL.SSL.Error, e:
if self.is_numtoolarge(e):
# warn, but ignore this exception
log.warning("Send: OpenSSL: asn1enc: first num too large (ignored)")
else:
log.error("Send: Caught OpenSSL.SSL.Error:", exc_info=True)
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return 0
class StdlibSSLWrapper(SSLWrapper):
'''Wrapper class for Python socket.ssl read() and write() methods'''
def __init__(self, *args):
self.parent = SSLWrapper
self.parent.__init__(self, *args)
def recv(self, bufsize, flags=None):
# we simply ignore flags since ssl object doesn't support it
try:
return self.sslobj.read(bufsize)
except socket.sslerror, e:
log.debug("Recv: Caught socket.sslerror: " + repr(e), exc_info=True)
if e.args[0] not in (socket.SSL_ERROR_WANT_READ, socket.SSL_ERROR_WANT_WRITE):
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return None
def send(self, data, flags=None, now=False):
# we simply ignore flags since ssl object doesn't support it
try:
return self.sslobj.write(data)
except socket.sslerror, e:
log.debug("Send: Caught socket.sslerror:", exc_info=True)
if e.args[0] not in (socket.SSL_ERROR_WANT_READ, socket.SSL_ERROR_WANT_WRITE):
raise SSLWrapper.Error(self.sock or self.sslobj, e)
return 0
class NonBlockingTLS(PlugIn):
'''
TLS connection used to encrypts already estabilished tcp connection.
Can be plugged into NonBlockingTCP and will make use of StdlibSSLWrapper or
PyOpenSSLWrapper.
'''
def __init__(self, cacerts, mycerts):
'''
:param cacerts: path to pem file with certificates of known XMPP servers
:param mycerts: path to pem file with certificates of user trusted servers
'''
PlugIn.__init__(self)
self.cacerts = cacerts
self.mycerts = mycerts
# from ssl.h (partial extract)
ssl_h_bits = { "SSL_ST_CONNECT": 0x1000, "SSL_ST_ACCEPT": 0x2000,
"SSL_CB_LOOP": 0x01, "SSL_CB_EXIT": 0x02,
"SSL_CB_READ": 0x04, "SSL_CB_WRITE": 0x08,
"SSL_CB_ALERT": 0x4000,
"SSL_CB_HANDSHAKE_START": 0x10, "SSL_CB_HANDSHAKE_DONE": 0x20}
def plugin(self, owner):
'''
Use to PlugIn TLS into transport and start establishing immediately
Returns True if TLS/SSL was established correctly, otherwise False.
'''
log.info('Starting TLS estabilishing')
try:
res = self._startSSL()
except Exception, e:
log.error("PlugIn: while trying _startSSL():", exc_info=True)
return False
return res
def _dumpX509(self, cert, stream=sys.stderr):
print >> stream, "Digest (SHA-1):", cert.digest("sha1")
print >> stream, "Digest (MD5):", cert.digest("md5")
print >> stream, "Serial #:", cert.get_serial_number()
print >> stream, "Version:", cert.get_version()
print >> stream, "Expired:", ("Yes" if cert.has_expired() else "No")
print >> stream, "Subject:"
self._dumpX509Name(cert.get_subject(), stream)
print >> stream, "Issuer:"
self._dumpX509Name(cert.get_issuer(), stream)
self._dumpPKey(cert.get_pubkey(), stream)
def _dumpX509Name(self, name, stream=sys.stderr):
print >> stream, "X509Name:", str(name)
def _dumpPKey(self, pkey, stream=sys.stderr):
typedict = {OpenSSL.crypto.TYPE_RSA: "RSA",
OpenSSL.crypto.TYPE_DSA: "DSA"}
print >> stream, "PKey bits:", pkey.bits()
print >> stream, "PKey type: %s (%d)" % (typedict.get(pkey.type(),
"Unknown"), pkey.type())
def _startSSL(self):
''' Immediatedly switch socket to TLS mode. Used internally.'''
log.debug("_startSSL called")
if USE_PYOPENSSL:
result = self._startSSL_pyOpenSSL()
else:
result = self._startSSL_stdlib()
if result:
log.debug('Synchronous handshake completed')
return True
else:
return False
def _load_cert_file(self, cert_path, cert_store, logg=True):
if not os.path.isfile(cert_path):
return
try:
f = open(cert_path)
except IOError, e:
log.warning('Unable to open certificate file %s: %s' % \
(cert_path, str(e)))
return
lines = f.readlines()
i = 0
begin = -1
for line in lines:
if 'BEGIN CERTIFICATE' in line:
begin = i
elif 'END CERTIFICATE' in line and begin > -1:
cert = ''.join(lines[begin:i+2])
try:
x509cert = OpenSSL.crypto.load_certificate(
OpenSSL.crypto.FILETYPE_PEM, cert)
cert_store.add_cert(x509cert)
except OpenSSL.crypto.Error, exception_obj:
if logg:
log.warning('Unable to load a certificate from file %s: %s' %\
(cert_path, exception_obj.args[0][0][2]))
except:
log.warning('Unknown error while loading certificate from file '
'%s' % cert_path)
begin = -1
i += 1
def _startSSL_pyOpenSSL(self):
log.debug("_startSSL_pyOpenSSL called")
tcpsock = self._owner
# See http://docs.python.org/dev/library/ssl.html
tcpsock._sslContext = OpenSSL.SSL.Context(OpenSSL.SSL.SSLv23_METHOD)
tcpsock.ssl_errnum = 0
tcpsock._sslContext.set_verify(OpenSSL.SSL.VERIFY_PEER,
self._ssl_verify_callback)
try:
tcpsock._sslContext.load_verify_locations(self.cacerts)
except:
log.warning('Unable to load SSL certificates from file %s' % \
os.path.abspath(self.cacerts))
store = tcpsock._sslContext.get_cert_store()
self._load_cert_file(self.mycerts, store)
if os.path.isdir('/etc/ssl/certs'):
for f in os.listdir('/etc/ssl/certs'):
# We don't logg because there is a lot a duplicated certs in this
# folder
self._load_cert_file(os.path.join('/etc/ssl/certs', f), store,
logg=False)
tcpsock._sslObj = OpenSSL.SSL.Connection(tcpsock._sslContext,
tcpsock._sock)
tcpsock._sslObj.set_connect_state() # set to client mode
wrapper = PyOpenSSLWrapper(tcpsock._sslObj)
tcpsock._recv = wrapper.recv
tcpsock._send = wrapper.send
log.debug("Initiating handshake...")
tcpsock._sslObj.setblocking(True)
try:
tcpsock._sslObj.do_handshake()
except:
log.error('Error while TLS handshake: ', exc_info=True)
return False
tcpsock._sslObj.setblocking(False)
self._owner.ssl_lib = PYOPENSSL
return True
def _startSSL_stdlib(self):
log.debug("_startSSL_stdlib called")
tcpsock=self._owner
try:
tcpsock._sock.setblocking(True)
tcpsock._sslObj = socket.ssl(tcpsock._sock, None, None)
tcpsock._sock.setblocking(False)
tcpsock._sslIssuer = tcpsock._sslObj.issuer()
tcpsock._sslServer = tcpsock._sslObj.server()
wrapper = StdlibSSLWrapper(tcpsock._sslObj, tcpsock._sock)
tcpsock._recv = wrapper.recv
tcpsock._send = wrapper.send
except:
log.error("Exception caught in _startSSL_stdlib:", exc_info=True)
return False
self._owner.ssl_lib = PYSTDLIB
return True
def _ssl_verify_callback(self, sslconn, cert, errnum, depth, ok):
# Exceptions can't propagate up through this callback, so print them here.
try:
self._owner.ssl_fingerprint_sha1 = cert.digest('sha1')
if errnum == 0:
return True
self._owner.ssl_errnum = errnum
self._owner.ssl_cert_pem = OpenSSL.crypto.dump_certificate(
OpenSSL.crypto.FILETYPE_PEM, cert)
return True
except:
log.error("Exception caught in _ssl_info_callback:", exc_info=True)
# Make sure something is printed, even if log is disabled.
traceback.print_exc()
# vim: se ts=3:
|