docker-offlineimap/offlineimap/imapserver.py
Sebastian Spaeth 3aded16ed4 Make releaseconnection a NOOP when conn is None
During cleanup we often call releaseconnection in a finally: block. But
in cases of error, we might have dropped the connection earlier already
and set it to "None". In this case don't fail releaseconnection() but
make it a NOOP.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
2011-11-02 10:37:17 +01:00

565 lines
24 KiB
Python

# IMAP server support
# Copyright (C) 2002 - 2011 John Goerzen & contributors
#
# 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 of the License, 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.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
from offlineimap import imaplibutil, imaputil, threadutil, OfflineImapError
from offlineimap.ui import getglobalui
from threading import Lock, BoundedSemaphore, Thread, Event, currentThread
from thread import get_ident # python < 2.6 support
import offlineimap.accounts
import hmac
import socket
import base64
import time
import errno
from sys import exc_info
from socket import gaierror
try:
from ssl import SSLError, cert_time_to_seconds
except ImportError:
# Protect against python<2.6, use dummy and won't get SSL errors.
SSLError = None
try:
# do we have a recent pykerberos?
have_gss = False
import kerberos
if 'authGSSClientWrap' in dir(kerberos):
have_gss = True
except ImportError:
pass
class IMAPServer:
"""Initializes all variables from an IMAPRepository() instance
Various functions, such as acquireconnection() return an IMAP4
object on which we can operate."""
GSS_STATE_STEP = 0
GSS_STATE_WRAP = 1
def __init__(self, repos):
self.ui = getglobalui()
self.repos = repos
self.config = repos.getconfig()
self.tunnel = repos.getpreauthtunnel()
self.usessl = repos.getssl()
self.username = None if self.tunnel else repos.getuser()
self.password = None
self.passworderror = None
self.goodpassword = None
self.hostname = None if self.tunnel else repos.gethost()
self.port = repos.getport()
if self.port == None:
self.port = 993 if self.usessl else 143
self.sslclientcert = repos.getsslclientcert()
self.sslclientkey = repos.getsslclientkey()
self.sslcacertfile = repos.getsslcacertfile()
if self.sslcacertfile is None:
self.verifycert = None # disable cert verification
self.delim = None
self.root = None
self.maxconnections = repos.getmaxconnections()
self.availableconnections = []
self.assignedconnections = []
self.lastowner = {}
self.semaphore = BoundedSemaphore(self.maxconnections)
self.connectionlock = Lock()
self.reference = repos.getreference()
self.idlefolders = repos.getidlefolders()
self.gss_step = self.GSS_STATE_STEP
self.gss_vc = None
self.gssapi = False
def getpassword(self):
"""Returns the server password or None"""
if self.goodpassword != None: # use cached good one first
return self.goodpassword
if self.password != None and self.passworderror == None:
return self.password # non-failed preconfigured one
# get 1) configured password first 2) fall back to asking via UI
self.password = self.repos.getpassword() or \
self.ui.getpass(self.repos.getname(), self.config,
self.passworderror)
self.passworderror = None
return self.password
def getdelim(self):
"""Returns this server's folder delimiter. Can only be called
after one or more calls to acquireconnection."""
return self.delim
def getroot(self):
"""Returns this server's folder root. Can only be called after one
or more calls to acquireconnection."""
return self.root
def releaseconnection(self, connection, drop_conn=False):
"""Releases a connection, returning it to the pool.
:param drop_conn: If True, the connection will be released and
not be reused. This can be used to indicate broken connections."""
if connection is None: return #noop on bad connection
self.connectionlock.acquire()
self.assignedconnections.remove(connection)
# Don't reuse broken connections
if connection.Terminate or drop_conn:
connection.logout()
else:
self.availableconnections.append(connection)
self.connectionlock.release()
self.semaphore.release()
def md5handler(self, response):
challenge = response.strip()
self.ui.debug('imap', 'md5handler: got challenge %s' % challenge)
passwd = self.getpassword()
retval = self.username + ' ' + hmac.new(passwd, challenge).hexdigest()
self.ui.debug('imap', 'md5handler: returning %s' % retval)
return retval
def plainauth(self, imapobj):
self.ui.debug('imap', 'Attempting plain authentication')
imapobj.login(self.username, self.getpassword())
def gssauth(self, response):
data = base64.b64encode(response)
try:
if self.gss_step == self.GSS_STATE_STEP:
if not self.gss_vc:
rc, self.gss_vc = kerberos.authGSSClientInit('imap@' +
self.hostname)
response = kerberos.authGSSClientResponse(self.gss_vc)
rc = kerberos.authGSSClientStep(self.gss_vc, data)
if rc != kerberos.AUTH_GSS_CONTINUE:
self.gss_step = self.GSS_STATE_WRAP
elif self.gss_step == self.GSS_STATE_WRAP:
rc = kerberos.authGSSClientUnwrap(self.gss_vc, data)
response = kerberos.authGSSClientResponse(self.gss_vc)
rc = kerberos.authGSSClientWrap(self.gss_vc, response,
self.username)
response = kerberos.authGSSClientResponse(self.gss_vc)
except kerberos.GSSError, err:
# Kerberos errored out on us, respond with None to cancel the
# authentication
self.ui.debug('imap', '%s: %s' % (err[0][0], err[1][0]))
return None
if not response:
response = ''
return base64.b64decode(response)
def acquireconnection(self):
"""Fetches a connection from the pool, making sure to create a new one
if needed, to obey the maximum connection limits, etc.
Opens a connection to the server and returns an appropriate
object."""
self.semaphore.acquire()
self.connectionlock.acquire()
imapobj = None
if len(self.availableconnections): # One is available.
# Try to find one that previously belonged to this thread
# as an optimization. Start from the back since that's where
# they're popped on.
imapobj = None
for i in range(len(self.availableconnections) - 1, -1, -1):
tryobj = self.availableconnections[i]
if self.lastowner[tryobj] == get_ident():
imapobj = tryobj
del(self.availableconnections[i])
break
if not imapobj:
imapobj = self.availableconnections[0]
del(self.availableconnections[0])
self.assignedconnections.append(imapobj)
self.lastowner[imapobj] = get_ident()
self.connectionlock.release()
return imapobj
self.connectionlock.release() # Release until need to modify data
""" Must be careful here that if we fail we should bail out gracefully
and release locks / threads so that the next attempt can try...
"""
success = 0
try:
while not success:
# Generate a new connection.
if self.tunnel:
self.ui.connecting('tunnel', self.tunnel)
imapobj = imaplibutil.IMAP4_Tunnel(self.tunnel,
timeout=socket.getdefaulttimeout())
success = 1
elif self.usessl:
self.ui.connecting(self.hostname, self.port)
fingerprint = self.repos.get_ssl_fingerprint()
imapobj = imaplibutil.WrappedIMAP4_SSL(self.hostname,
self.port,
self.sslclientkey,
self.sslclientcert,
self.sslcacertfile,
self.verifycert,
timeout=socket.getdefaulttimeout(),
fingerprint=fingerprint
)
else:
self.ui.connecting(self.hostname, self.port)
imapobj = imaplibutil.WrappedIMAP4(self.hostname, self.port,
timeout=socket.getdefaulttimeout())
if not self.tunnel:
try:
# Try GSSAPI and continue if it fails
if 'AUTH=GSSAPI' in imapobj.capabilities and have_gss:
self.connectionlock.acquire()
self.ui.debug('imap',
'Attempting GSSAPI authentication')
try:
imapobj.authenticate('GSSAPI', self.gssauth)
except imapobj.error, val:
self.gssapi = False
self.ui.debug('imap',
'GSSAPI Authentication failed')
else:
self.gssapi = True
kerberos.authGSSClientClean(self.gss_vc)
self.gss_vc = None
self.gss_step = self.GSS_STATE_STEP
#if we do self.password = None then the next attempt cannot try...
#self.password = None
self.connectionlock.release()
if not self.gssapi:
if 'STARTTLS' in imapobj.capabilities and not\
self.usessl:
self.ui.debug('imap',
'Using STARTTLS connection')
imapobj.starttls()
if 'AUTH=CRAM-MD5' in imapobj.capabilities:
self.ui.debug('imap',
'Attempting CRAM-MD5 authentication')
try:
imapobj.authenticate('CRAM-MD5',
self.md5handler)
except imapobj.error, val:
self.plainauth(imapobj)
else:
# Use plaintext login, unless
# LOGINDISABLED (RFC2595)
if 'LOGINDISABLED' in imapobj.capabilities:
raise OfflineImapError("Plaintext login "
"disabled by server. Need to use SSL?",
OfflineImapError.ERROR.REPO)
self.plainauth(imapobj)
# Would bail by here if there was a failure.
success = 1
self.goodpassword = self.password
except imapobj.error, val:
self.passworderror = str(val)
raise
# update capabilities after login, e.g. gmail serves different ones
typ, dat = imapobj.capability()
if dat != [None]:
imapobj.capabilities = tuple(dat[-1].upper().split())
if self.delim == None:
listres = imapobj.list(self.reference, '""')[1]
if listres == [None] or listres == None:
# Some buggy IMAP servers do not respond well to LIST "" ""
# Work around them.
listres = imapobj.list(self.reference, '"*"')[1]
if listres == [None] or listres == None:
# No Folders were returned. This occurs, e.g. if the
# 'reference' prefix does not exist on the mail
# server. Raise exception.
err = "Server '%s' returned no folders in '%s'" % \
(self.repos.getname(), self.reference)
self.ui.warn(err)
raise Exception(err)
self.delim, self.root = \
imaputil.imapsplit(listres[0])[1:]
self.delim = imaputil.dequote(self.delim)
self.root = imaputil.dequote(self.root)
self.connectionlock.acquire()
self.assignedconnections.append(imapobj)
self.lastowner[imapobj] = get_ident()
self.connectionlock.release()
return imapobj
except Exception, e:
"""If we are here then we did not succeed in getting a
connection - we should clean up and then re-raise the
error..."""
self.semaphore.release()
if(self.connectionlock.locked()):
self.connectionlock.release()
severity = OfflineImapError.ERROR.REPO
if type(e) == gaierror:
#DNS related errors. Abort Repo sync
#TODO: special error msg for e.errno == 2 "Name or service not known"?
reason = "Could not resolve name '%s' for repository "\
"'%s'. Make sure you have configured the ser"\
"ver name correctly and that you are online."%\
(self.hostname, self.repos)
raise OfflineImapError(reason, severity)
elif SSLError and isinstance(e, SSLError) and e.errno == 1:
# SSL unknown protocol error
# happens e.g. when connecting via SSL to a non-SSL service
if self.port != 993:
reason = "Could not connect via SSL to host '%s' and non-s"\
"tandard ssl port %d configured. Make sure you connect"\
" to the correct port." % (self.hostname, self.port)
else:
reason = "Unknown SSL protocol connecting to host '%s' for"\
"repository '%s'. OpenSSL responded:\n%s"\
% (self.hostname, self.repos, e)
raise OfflineImapError(reason, severity)
elif isinstance(e, socket.error) and e.args[0] == errno.ECONNREFUSED:
# "Connection refused", can be a non-existing port, or an unauthorized
# webproxy (open WLAN?)
reason = "Connection to host '%s:%d' for repository '%s' was "\
"refused. Make sure you have the right host and port "\
"configured and that you are actually able to access the "\
"network." % (self.hostname, self.port, self.reposname)
raise OfflineImapError(reason, severity)
# Could not acquire connection to the remote;
# socket.error(last_error) raised
if str(e)[:24] == "can't open socket; error":
raise OfflineImapError("Could not connect to remote server '%s' "\
"for repository '%s'. Remote does not answer."
% (self.hostname, self.repos),
OfflineImapError.ERROR.REPO)
else:
# re-raise all other errors
raise
def connectionwait(self):
"""Waits until there is a connection available. Note that between
the time that a connection becomes available and the time it is
requested, another thread may have grabbed it. This function is
mainly present as a way to avoid spawning thousands of threads
to copy messages, then have them all wait for 3 available connections.
It's OK if we have maxconnections + 1 or 2 threads, which is what
this will help us do."""
self.semaphore.acquire()
self.semaphore.release()
def close(self):
# Make sure I own all the semaphores. Let the threads finish
# their stuff. This is a blocking method.
self.connectionlock.acquire()
threadutil.semaphorereset(self.semaphore, self.maxconnections)
for imapobj in self.assignedconnections + self.availableconnections:
imapobj.logout()
self.assignedconnections = []
self.availableconnections = []
self.lastowner = {}
# reset kerberos state
self.gss_step = self.GSS_STATE_STEP
self.gss_vc = None
self.gssapi = False
self.connectionlock.release()
def keepalive(self, timeout, event):
"""Sends a NOOP to each connection recorded. It will wait a maximum
of timeout seconds between doing this, and will continue to do so
until the Event object as passed is true. This method is expected
to be invoked in a separate thread, which should be join()'d after
the event is set."""
self.ui.debug('imap', 'keepalive thread started')
while 1:
self.ui.debug('imap', 'keepalive: top of loop')
if event.isSet():
self.ui.debug('imap', 'keepalive: event is set; exiting')
return
self.ui.debug('imap', 'keepalive: acquiring connectionlock')
self.connectionlock.acquire()
numconnections = len(self.assignedconnections) + \
len(self.availableconnections)
self.connectionlock.release()
self.ui.debug('imap', 'keepalive: connectionlock released')
threads = []
for i in range(numconnections):
self.ui.debug('imap', 'keepalive: processing connection %d of %d' % (i, numconnections))
if len(self.idlefolders) > i:
idler = IdleThread(self, self.idlefolders[i])
else:
idler = IdleThread(self)
idler.start()
threads.append(idler)
self.ui.debug('imap', 'keepalive: thread started')
self.ui.debug('imap', 'keepalive: waiting for timeout')
event.wait(timeout)
self.ui.debug('imap', 'keepalive: after wait')
self.ui.debug('imap', 'keepalive: joining threads')
for idler in threads:
# Make sure all the commands have completed.
idler.stop()
idler.join()
self.ui.debug('imap', 'keepalive: bottom of loop')
def verifycert(self, cert, hostname):
'''Verify that cert (in socket.getpeercert() format) matches hostname.
CRLs are not handled.
Returns error message if any problems are found and None on success.
'''
errstr = "CA Cert verifying failed: "
if not cert:
return ('%s no certificate received' % errstr)
dnsname = hostname.lower()
certnames = []
# cert expired?
notafter = cert.get('notAfter')
if notafter:
if time.time() >= cert_time_to_seconds(notafter):
return '%s certificate expired %s' % (errstr, notafter)
# First read commonName
for s in cert.get('subject', []):
key, value = s[0]
if key == 'commonName':
certnames.append(value.lower())
if len(certnames) == 0:
return ('%s no commonName found in certificate' % errstr)
# Then read subjectAltName
for key, value in cert.get('subjectAltName', []):
if key == 'DNS':
certnames.append(value.lower())
# And finally try to match hostname with one of these names
for certname in certnames:
if (certname == dnsname or
'.' in dnsname and certname == '*.' + dnsname.split('.', 1)[1]):
return None
return ('%s no matching domain name found in certificate' % errstr)
class IdleThread(object):
def __init__(self, parent, folder=None):
"""If invoked without 'folder', perform a NOOP and wait for
self.stop() to be called. If invoked with folder, switch to IDLE
mode and synchronize once we have a new message"""
self.parent = parent
self.folder = folder
self.stop_sig = Event()
self.ui = getglobalui()
if folder is None:
self.thread = Thread(target=self.noop)
else:
self.thread = Thread(target=self.idle)
self.thread.setDaemon(1)
def start(self):
self.thread.start()
def stop(self):
self.stop_sig.set()
def join(self):
self.thread.join()
def noop(self):
imapobj = self.parent.acquireconnection()
imapobj.noop()
self.stop_sig.wait()
self.parent.releaseconnection(imapobj)
def dosync(self):
remoterepos = self.parent.repos
account = remoterepos.account
localrepos = account.localrepos
remoterepos = account.remoterepos
statusrepos = account.statusrepos
remotefolder = remoterepos.getfolder(self.folder)
offlineimap.accounts.syncfolder(account.name, remoterepos, remotefolder, localrepos, statusrepos, quick=False)
ui = getglobalui()
ui.unregisterthread(currentThread())
def idle(self):
"""Invoke IDLE mode until timeout or self.stop() is invoked"""
def callback(args):
"""IDLE callback function invoked by imaplib2
This is invoked when a) The IMAP server tells us something
while in IDLE mode, b) we get an Exception (e.g. on dropped
connections, or c) the standard imaplib IDLE timeout of 29
minutes kicks in."""
result, cb_arg, exc_data = args
if exc_data is None and not self.stop_sig.isSet():
# No Exception, and we are not supposed to stop:
self.needsync = True
self.stop_sig.set() # continue to sync
while not self.stop_sig.isSet():
self.needsync = False
success = False # successfully selected FOLDER?
while not success:
imapobj = self.parent.acquireconnection()
try:
imapobj.select(self.folder)
except OfflineImapError, e:
if e.severity == OfflineImapError.ERROR.FOLDER_RETRY:
# Connection closed, release connection and retry
self.ui.error(e, exc_info()[2])
self.parent.releaseconnection(imapobj, True)
else:
raise e
else:
success = True
if "IDLE" in imapobj.capabilities:
imapobj.idle(callback=callback)
else:
self.ui.warn("IMAP IDLE not supported on server '%s'."
"Sleep until next refresh cycle." % imapobj.identifier)
imapobj.noop()
self.stop_sig.wait() # self.stop() or IDLE callback are invoked
try:
# End IDLE mode with noop, imapobj can point to a dropped conn.
imapobj.noop()
except imapobj.abort:
self.ui.warn('Attempting NOOP on dropped connection %s' % \
imapobj.identifier)
self.parent.releaseconnection(imapobj, True)
else:
self.parent.releaseconnection(imapobj)
if self.needsync:
# here not via self.stop, but because IDLE responded. Do
# another round and invoke actual syncing.
self.stop_sig.clear()
self.dosync()