path: root/nbxmpp/transports_nb.py

##   transports_nb.py
##       based on transports.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.

"""
Transports are objects responsible for connecting to XMPP server and putting
data to wrapped sockets in in desired form (SSL, TLS, TCP, for HTTP proxy,
for SOCKS5 proxy...)

Transports are not aware of XMPP stanzas and only responsible for low-level
connection handling.
"""

from __future__ import unicode_literals

from .simplexml import ustr
from .plugin import PlugIn
from .idlequeue import IdleObject
from . import proxy_connectors
from . import tls_nb

import socket
import errno
import time
import traceback
import base64

try:
    from urllib.parse import urlparse
except ImportError:
    from urlparse import urlparse

import logging
log = logging.getLogger('nbxmpp.transports_nb')

def urisplit(uri):
    """
    Function for splitting URI string to tuple (protocol, host, port, path).
    e.g. urisplit('http://httpcm.jabber.org:123/webclient') returns ('http',
    'httpcm.jabber.org', 123, '/webclient') return 443 as default port if proto
    is https else 80
    """
    splitted =  urlparse(uri)
    proto, host, path = splitted.scheme, splitted.hostname, splitted.path
    try:
        port = splitted.port
    except ValueError:
        log.warning('port cannot be extracted from BOSH URL %s, using default port' \
                % uri)
        port = ''
    if not port:
        if proto == 'https':
            port = 443
        else:
            port = 80
    return proto, host, port, path

def get_proxy_data_from_dict(proxy):
    tcp_host, tcp_port, proxy_user, proxy_pass = None, None, None, None
    proxy_type = proxy['type']
    if proxy_type == 'bosh' and not proxy['bosh_useproxy']:
        # with BOSH not over proxy we have to parse the hostname from BOSH URI
        proto, tcp_host, tcp_port, path = urisplit(proxy['bosh_uri'])
    else:
        # with proxy!=bosh or with bosh over HTTP proxy we're connecting to proxy
        # machine
        tcp_host, tcp_port = proxy['host'], proxy['port']
    if proxy.get('useauth', False):
        proxy_user, proxy_pass = proxy['user'], proxy['pass']
    return tcp_host, tcp_port, proxy_user, proxy_pass

#: timeout to connect to the server socket, it doesn't include auth
CONNECT_TIMEOUT_SECONDS = 30

#: how long to wait for a disconnect to complete
DISCONNECT_TIMEOUT_SECONDS = 5

#: size of the buffer which reads data from server
# if lower, more stanzas will be fragmented and processed twice
RECV_BUFSIZE = 32768 # 2x maximum size of ssl packet, should be plenty
# it's inefficient but should work. Problem is that connect machine makes wrong
# assumptions and that we only check for pending data in sockets but not in SSL
# buffer...

DATA_RECEIVED = 'DATA RECEIVED'
DATA_SENT = 'DATA SENT'
DATA_ERROR = 'DATA ERROR'

DISCONNECTED = 'DISCONNECTED'
DISCONNECTING = 'DISCONNECTING'
CONNECTING = 'CONNECTING'
PROXY_CONNECTING = 'PROXY_CONNECTING'
CONNECTED = 'CONNECTED'
STATES = (DISCONNECTED, CONNECTING, PROXY_CONNECTING, CONNECTED, DISCONNECTING)

class NonBlockingTransport(PlugIn):
    """
    Abstract class representing a transport

    Subclasses CAN have different constructor signature but connect method SHOULD
    be the same.
    """

    def __init__(self, raise_event, on_disconnect, idlequeue, estabilish_tls,
    certs, tls_version, cipher_list):
        """
        Each trasport class can have different constructor but it has to have at
        least all the arguments of NonBlockingTransport constructor

        :param raise_event: callback for monitoring of sent and received data
        :param on_disconnect: callback called on disconnection during runtime
        :param idlequeue: processing idlequeue
        :param estabilish_tls: boolean whether to estabilish TLS connection
            after TCP connection is done
        :param certs: tuple of (cacerts, mycerts) see constructor
            of tls_nb.NonBlockingTLS for more details
        :param tls_version: The lowest supported TLS version.
        :param cipher_list: list of ciphers used to connect to server
        """
        PlugIn.__init__(self)
        self.raise_event = raise_event
        self.on_disconnect = on_disconnect
        self.on_connect = None
        self.on_connect_failure = None
        self.idlequeue = idlequeue
        self.on_receive = None
        self.server = None
        self.port = None
        self.conn_5tuple = None
        self.set_state(DISCONNECTED)
        self.estabilish_tls = estabilish_tls
        self.certs = certs
        self.tls_version = tls_version
        self.cipher_list = cipher_list
        # type of used ssl lib (if any) will be assigned to this member var
        self.ssl_lib = None
        self._exported_methods=[self.onreceive, self.set_send_timeout,
                self.set_send_timeout2, self.set_timeout, self.remove_timeout,
                self.start_disconnect]

        # time to wait for SOME stanza to come and then send keepalive
        self.sendtimeout = 0

        # in case we want to something different than sending keepalives
        self.on_timeout = None
        self.on_timeout2 = None

    def plugin(self, owner):
        owner.Connection = self

    def plugout(self):
        self._owner.Connection = None
        self._owner = None
        self.disconnect(do_callback=False)

    def connect(self, conn_5tuple, on_connect, on_connect_failure):
        """
        Creates and connects transport to server and port defined in conn_5tuple
        which should be item from list returned from getaddrinfo

        :param conn_5tuple: 5-tuple returned from getaddrinfo
        :param on_connect: callback called on successful connect to the server
        :param on_connect_failure: callback called on failure when connecting
        """
        self.on_connect = on_connect
        self.on_connect_failure = on_connect_failure
        self.server, self.port = conn_5tuple[4][:2]
        self.conn_5tuple = conn_5tuple

    def set_state(self, newstate):
        assert(newstate in STATES)
        self.state = newstate

    def get_state(self):
        return self.state

    def _on_connect(self):
        """
        Preceeds call of on_connect callback
        """
        # data is reference to socket wrapper instance. We don't need it in client
        # because
        self.set_state(CONNECTED)
        self.on_connect()

    def _on_connect_failure(self, err_message):
        """
        Preceeds call of on_connect_failure callback
        """
        # In case of error while connecting we need to disconnect transport
        # but we don't want to call DisconnectHandlers from client,
        # thus the do_callback=False
        self.disconnect(do_callback=False)
        self.on_connect_failure(err_message=err_message)

    def send(self, raw_data, now=False):
        if self.get_state() == DISCONNECTED:
            log.error('Unable to send %s \n because state is %s.' %
                    (raw_data, self.get_state()))

    def disconnect(self, do_callback=True):
        self.set_state(DISCONNECTED)
        if do_callback:
            # invoke callback given in __init__
            self.on_disconnect()

    def onreceive(self, recv_handler):
        """
        Set the on_receive callback.

        onreceive(None) sets callback to Dispatcher.ProcessNonBlocking which is
        the default one that will decide what to do with received stanza based on
        its tag name and namespace.

        Do not confuse it with on_receive() method, which is the callback
        itself.
        """
        if not recv_handler:
            if hasattr(self, '_owner') and hasattr(self._owner, 'Dispatcher'):
                self.on_receive = self._owner.Dispatcher.ProcessNonBlocking
            else:
                log.warning('No Dispatcher plugged. Received data will not be processed')
                self.on_receive = None
            return
        self.on_receive = recv_handler

    def _tcp_connecting_started(self):
        self.set_state(CONNECTING)

    def read_timeout(self):
        """
        Called when there's no response from server in defined timeout
        """
        if self.on_timeout:
            self.on_timeout()
        self.renew_send_timeout()

    def read_timeout2(self):
        """
        called when there's no response from server in defined timeout
        """
        if self.on_timeout2:
            self.on_timeout2()
        self.renew_send_timeout2()

    def renew_send_timeout(self):
        if self.on_timeout and self.sendtimeout > 0:
            self.set_timeout(self.sendtimeout)

    def renew_send_timeout2(self):
        if self.on_timeout2 and self.sendtimeout2 > 0:
            self.set_timeout2(self.sendtimeout2)

    def set_timeout(self, timeout):
        self.idlequeue.set_read_timeout(self.fd, timeout)

    def set_timeout2(self, timeout2):
        self.idlequeue.set_read_timeout(self.fd, timeout2, self.read_timeout2)

    def get_fd(self):
        pass

    def remove_timeout(self):
        self.idlequeue.remove_timeout(self.fd)

    def set_send_timeout(self, timeout, on_timeout):
        self.sendtimeout = timeout
        if self.sendtimeout > 0:
            self.on_timeout = on_timeout
        else:
            self.on_timeout = None

    def set_send_timeout2(self, timeout2, on_timeout2):
        self.sendtimeout2 = timeout2
        if self.sendtimeout2 > 0:
            self.on_timeout2 = on_timeout2
        else:
            self.on_timeout2 = None

    # FIXME: where and why does this need to be called
    def start_disconnect(self):
        self.set_state(DISCONNECTING)


class NonBlockingTCP(NonBlockingTransport, IdleObject):
    """
    Non-blocking TCP socket wrapper

    It is used for simple XMPP connection. Can be connected via proxy and can
    estabilish TLS connection.
    """
    def __init__(self, raise_event, on_disconnect, idlequeue, estabilish_tls,
    certs, tls_version, cipher_list, proxy_dict=None):
        """
        :param proxy_dict: dictionary with proxy data as loaded from config file
        """
        NonBlockingTransport.__init__(self, raise_event, on_disconnect,
            idlequeue, estabilish_tls, certs, tls_version, cipher_list)
        IdleObject.__init__(self)

        # queue with messages to be send
        self.sendqueue = []

        # bytes remained from the last send message
        self.sendbuff = ''
        self.sent_bytes_buff = b''

        # bytes remained from the last received message
        self.received_bytes_buff = b''

        self.proxy_dict = proxy_dict
        self.on_remote_disconnect = self.disconnect

        # ssl variables
        self.ssl_certificate = None
        self.ssl_errnum = 0

    # FIXME: transport should not be aware xmpp
    def start_disconnect(self):
        NonBlockingTransport.start_disconnect(self)
        self.send('</stream:stream>', now=True)
        self.disconnect()

    def connect(self, conn_5tuple, on_connect, on_connect_failure):
        NonBlockingTransport.connect(self, conn_5tuple, on_connect,
                on_connect_failure)
        log.info('NonBlockingTCP Connect :: About to connect to %s:%s' %
                (self.server, self.port))

        try:
            self._sock = socket.socket(*conn_5tuple[:3])
        except socket.error as e:
            self._on_connect_failure('NonBlockingTCP Connect: Error while creating\
                    socket: %s' % atr(e))
            return

        self._send = self._sock.send
        self._recv = self._sock.recv
        self.fd = self._sock.fileno()

        # we want to be notified when send is possible to connected socket because
        # it means the TCP connection is estabilished
        self._plug_idle(writable=True, readable=False)
        self.peerhost = None

        # variable for errno symbol that will be found from exception raised
        # from connect()
        errnum = 0
        errstr = str()

        # set timeout for TCP connecting - if nonblocking connect() fails, pollend
        # is called. If if succeeds pollout is called.
        self.idlequeue.set_read_timeout(self.fd, CONNECT_TIMEOUT_SECONDS)

        try:
            self._sock.setblocking(False)
            self._sock.connect((self.server, self.port))
        except Exception as exc:
            errnum, errstr = exc.errno, exc.strerror

        if errnum in (errno.EINPROGRESS, errno.EALREADY, errno.EWOULDBLOCK):
            # connecting in progress
            log.info('After NB connect() of %s. "%s" raised => CONNECTING' %
                    (id(self), errstr))
            self._tcp_connecting_started()
            return

        # if there was some other exception, call failure callback and unplug
        # transport which will also remove read_timeouts for descriptor
        self._on_connect_failure('Exception while connecting to %s:%s - %s %s' %
                (self.server, self.port, errnum, errstr))

    def _connect_to_proxy(self):
        self.set_state(PROXY_CONNECTING)
        if self.proxy_dict['type']   == 'socks5':
            proxyclass = proxy_connectors.SOCKS5Connector
        elif self.proxy_dict['type'] == 'http'  :
            proxyclass = proxy_connectors.HTTPCONNECTConnector
        proxyclass.get_instance(
                send_method=self.send,
                onreceive=self.onreceive,
                old_on_receive=self.on_receive,
                on_success=self._on_connect,
                on_failure=self._on_connect_failure,
                xmpp_server=self.proxy_dict['xmpp_server'],
                proxy_creds=self.proxy_dict['credentials'])

    def _on_connect(self):
        """
        Preceed invoking of on_connect callback. TCP connection is already
        estabilished by this time
        """
        if self.estabilish_tls:
            self.tls_init(
                    on_succ = lambda: NonBlockingTransport._on_connect(self),
                    on_fail = lambda: self._on_connect_failure(
                            'error while estabilishing TLS'))
        else:
            NonBlockingTransport._on_connect(self)

    def tls_init(self, on_succ, on_fail):
        """
        Estabilishes TLS/SSL using this TCP connection by plugging a
        NonBlockingTLS module
        """
        cacerts, mycerts = self.certs
        result = tls_nb.NonBlockingTLS.get_instance(cacerts, mycerts,
            self.tls_version, self.cipher_list).PlugIn(self)
        if result:
            on_succ()
        else:
            on_fail()

    def pollin(self):
        """
        Called by idlequeu when receive on plugged socket is possible
        """
        log.info('pollin called, state == %s' % self.get_state())
        self._do_receive()

    def pollout(self):
        """
        Called by idlequeu when send to plugged socket is possible
        """
        log.info('pollout called, state == %s' % self.get_state())

        if self.get_state() == CONNECTING:
            log.info('%s socket wrapper connected' % id(self))
            self.idlequeue.remove_timeout(self.fd)
            self._plug_idle(writable=False, readable=False)
            self.peerhost  = self._sock.getsockname()
            if self.proxy_dict:
                self._connect_to_proxy()
            else:
                self._on_connect()
        else:
            self._do_send()

    def pollend(self):
        """
        Called by idlequeue on TCP connection errors
        """
        log.info('pollend called, state == %s' % self.get_state())

        if self.get_state() == CONNECTING:
            self._on_connect_failure('Error during connect to %s:%s' %
                    (self.server, self.port))
        else:
            self.disconnect()

    def disconnect(self, do_callback=True):
        if self.get_state() == DISCONNECTED:
            return
        self.set_state(DISCONNECTED)
        self.idlequeue.unplug_idle(self.fd)
        if 'NonBlockingTLS' in self.__dict__:
            self.NonBlockingTLS.PlugOut()
        try:
            self._sock.shutdown(socket.SHUT_RDWR)
            self._sock.close()
        except socket.error as e:
            log.info('Error while disconnecting socket: %s' % str(e))
        self.fd = -1
        NonBlockingTransport.disconnect(self, do_callback)

    def read_timeout(self):
        log.info('read_timeout called, state == %s' % self.get_state())
        if self.get_state() == CONNECTING:
            # if read_timeout is called during connecting, connect() didn't end yet
            # thus we have to call the tcp failure callback
            self._on_connect_failure('Error during connect to %s:%s' %
                    (self.server, self.port))
        else:
            NonBlockingTransport.read_timeout(self)

    def set_timeout(self, timeout):
        if self.get_state() != DISCONNECTED and self.fd != -1:
            NonBlockingTransport.set_timeout(self, timeout)
        else:
            log.warning('set_timeout: TIMEOUT NOT SET: state is %s, fd is %s' %
                    (self.get_state(), self.fd))

    def remove_timeout(self):
        if self.fd:
            NonBlockingTransport.remove_timeout(self)
        else:
            log.warning('remove_timeout: no self.fd state is %s' % self.get_state())

    def send(self, raw_data, now=False):
        """
        Append raw_data to the queue of messages to be send. If supplied data is
        unicode string, encode it to utf-8.
        """
        NonBlockingTransport.send(self, raw_data, now)

        if isinstance(raw_data, bytes):
            r = raw_data
        else:
            r = self.encode_stanza(raw_data)

        if now:
            self.sendqueue.insert(0, r)
            self._do_send()
        else:
            self.sendqueue.append(r)

        self._plug_idle(writable=True, readable=True)

    def encode_stanza(self, stanza):
        """
        Encode str or unicode to utf-8
        """
        if isinstance(stanza, str):
            stanza = stanza.encode('utf-8')
        elif not isinstance(stanza, str):
            stanza = ustr(stanza).encode('utf-8')
        return stanza

    def _plug_idle(self, writable, readable):
        """
        Plug file descriptor of socket to Idlequeue

        Plugged socket will be watched for "send possible" or/and "recv possible"
        events. pollin() callback is invoked on "recv possible", pollout() on
        "send_possible".

        Plugged socket will always be watched for "error" event - in that case,
        pollend() is called.
        """
        log.info('Plugging fd %d, W:%s, R:%s' % (self.fd, writable, readable))
        self.idlequeue.plug_idle(self, writable, readable)

    def _do_send(self):
        """
        Called when send() to connected socket is possible. First message from
        sendqueue will be sent
        """
        if not self.sendbuff:
            if not self.sendqueue:
                log.warning('calling send on empty buffer and queue')
                self._plug_idle(writable=False, readable=True)
                return None
            self.sendbuff = self.sendqueue.pop(0)
        try:
            send_count = self._send(self.sendbuff.encode("utf-8"))
            if send_count:
                sent_data = self.sendbuff[:send_count]
                self.sendbuff = self.sendbuff[send_count:]
                self._plug_idle(writable=(self.sendqueue != []), readable=True)

                if self.sent_bytes_buff:
                    sent_data = self.sent_bytes_buff + sent_data
                    self.sent_bytes_buff = b''
                # try to decode sent data
                try:
                    sent_data = sent_data.decode('utf-8')
                except UnicodeDecodeError:
                    for i in range(-1, -4, -1):
                        char = sent_data[i]
                        if char & 0xc0 == 0xc0:
                            self.sent_bytes_buff = sent_data[i:]
                            sent_data = sent_data[:i]
                            break
                    sent_data = sent_data.decode('utf-8')
                self.raise_event(DATA_SENT, sent_data)

        except Exception:
            log.error('_do_send:', exc_info=True)
            traceback.print_exc()
            self.disconnect()

    def _do_receive(self):
        """
        Reads all pending incoming data. Will call owner's disconnected() method
        if appropriate
        """
        received = None
        errnum = 0
        errstr = 'No Error Set'

        try:
            # get as many bites, as possible, but not more than RECV_BUFSIZE
            received = self._recv(RECV_BUFSIZE)
        except socket.error as e:
            log.info("_do_receive: got %s:" % received, exc_info=True)
        except tls_nb.SSLWrapper.Error as e:
            log.info("_do_receive, caught SSL error, got %s:" % received,
                    exc_info=True)
            errnum, errstr = e.errno, e.strerror

        if received == '':
            errstr = 'zero bytes on recv'

        if (self.ssl_lib is None and received == '') or \
        (self.ssl_lib == tls_nb.PYSTDLIB  and errnum ==  8 ) or \
        (self.ssl_lib == tls_nb.PYOPENSSL and errnum == -1 ):
            #  8 in stdlib: errstr == EOF occured in violation of protocol
            # -1 in pyopenssl: errstr == Unexpected EOF
            log.info("Disconnected by remote server: #%s, %s" % (errnum, errstr))
            self.on_remote_disconnect()
            return

        if errnum:
            log.info("Connection to %s:%s lost: %s %s" % (self.server, self.port,
                    errnum, errstr), exc_info=True)
            self.disconnect()
            return

        # this branch is for case of non-fatal SSL errors - None is returned from
        # recv() but no errnum is set
        if received is None:
            return

        # we have received some bytes, stop the timeout!
        self.remove_timeout()
        self.renew_send_timeout()
        self.renew_send_timeout2()

        if self.received_bytes_buff:
            received = self.received_bytes_buff + received
            self.received_bytes_buff = b''

        # try to decode data
        try:
            received = received.decode('utf-8')
        except UnicodeDecodeError:
            for i in range(-1, -4, -1):
                char = received[i]
                if char & 0xc0 == 0xc0:
                    self.received_bytes_buff = received[i:]
                    received = received[:i]
                    break
            received = received.decode('utf-8')

        # pass received data to owner
        if self.on_receive:
            self.raise_event(DATA_RECEIVED, received)
            self._on_receive(received)
        else:
            # This should never happen, so we need the debug.
            # (If there is no handler on receive specified, data is passed to
            # Dispatcher.ProcessNonBlocking)
            log.error('SOCKET %s Unhandled data received: %s' % (id(self),
                    received))
            self.disconnect()

    def _on_receive(self, data):
        """
        Preceeds on_receive callback. It peels off and checks HTTP headers in
        HTTP classes, in here it just calls the callback
        """
        self.on_receive(data)


class NonBlockingHTTP(NonBlockingTCP):
    """
    Socket wrapper that creates HTTP message out of sent data and peels-off HTTP
    headers from incoming messages
    """

    def __init__(self, raise_event, on_disconnect, idlequeue, estabilish_tls,
    certs, tls_version, cipher_list, on_http_request_possible, on_persistent_fallback,
    http_dict, proxy_dict=None):
        """
        :param on_http_request_possible: method to call when HTTP request to
                socket owned by transport is possible.
        :param on_persistent_fallback: callback called when server ends TCP
                connection. It doesn't have to be fatal for HTTP session.
        :param http_dict: dictionary with data for HTTP request and headers
        """
        NonBlockingTCP.__init__(self, raise_event, on_disconnect, idlequeue,
            estabilish_tls, certs, tls_version, cipher_list, proxy_dict)

        self.http_protocol, self.http_host, self.http_port, self.http_path = \
            urisplit(http_dict['http_uri'])
        self.http_protocol = self.http_protocol or 'http'
        self.http_path = self.http_path or '/'
        self.http_version = http_dict['http_version']
        self.http_persistent = http_dict['http_persistent']
        self.add_proxy_headers =  http_dict['add_proxy_headers']

        if 'proxy_user' in http_dict and 'proxy_pass' in http_dict:
            self.proxy_user, self.proxy_pass = http_dict['proxy_user'], http_dict[
                    'proxy_pass']
        else:
            self.proxy_user, self.proxy_pass = None, None

        # buffer for partial responses
        self.recvbuff = ''
        self.expected_length = 0
        self.pending_requests = 0
        self.on_http_request_possible = on_http_request_possible
        self.last_recv_time = 0
        self.close_current_connection = False
        self.on_remote_disconnect = lambda: on_persistent_fallback(self)

    def http_send(self, raw_data, now=False):
        self.send(self.build_http_message(raw_data), now)

    def _on_receive(self, data):
        """
        Preceeds passing received data to owner class. Gets rid of HTTP headers
        and checks them.
        """
        if self.get_state() == PROXY_CONNECTING:
            NonBlockingTCP._on_receive(self, data)
            return

        # append currently received data to HTTP msg in buffer
        self.recvbuff = '%s%s' % (self.recvbuff or '', data)
        statusline, headers, httpbody, buffer_rest = self.parse_http_message(
                self.recvbuff)

        if not (statusline and headers and httpbody):
            log.debug('Received incomplete HTTP response')
            return

        if statusline[1] != '200':
            log.error('HTTP Error: %s %s' % (statusline[1], statusline[2]))
            self.disconnect()
            return
        self.expected_length = int(headers['Content-Length'])
        if 'Connection' in headers and headers['Connection'].strip()=='close':
            self.close_current_connection = True

        if self.expected_length > len(httpbody):
            # If we haven't received the whole HTTP mess yet, let's end the thread.
            # It will be finnished from one of following recvs on plugged socket.
            log.info('not enough bytes in HTTP response - %d expected, got %d' %
                    (self.expected_length, len(httpbody)))
        else:
            # First part of buffer has been extraced and is going to be handled,
            # remove it from buffer
            self.recvbuff = buffer_rest

            # everything was received
            self.expected_length = 0

            if not self.http_persistent or self.close_current_connection:
                # not-persistent connections disconnect after response
                self.disconnect(do_callback=False)
            self.close_current_connection = False
            self.last_recv_time = time.time()
            self.on_receive(data=httpbody, socket=self)
            self.on_http_request_possible()

    def build_http_message(self, httpbody, method='POST'):
        """
        Builds http message with given body. Values for headers and status line
        fields are taken from class variables
        """
        absolute_uri = '%s://%s:%s%s' % (self.http_protocol, self.http_host,
                self.http_port, self.http_path)
        headers = ['%s %s %s' % (method, absolute_uri, self.http_version),
                'Host: %s:%s' % (self.http_host, self.http_port),
                'User-Agent: Gajim',
                'Content-Type: text/xml; charset=utf-8',
                'Content-Length: %s' % len(str(httpbody))]
        if self.add_proxy_headers:
            headers.append('Proxy-Connection: keep-alive')
            headers.append('Pragma: no-cache')
            if self.proxy_user and self.proxy_pass:
                credentials = '%s:%s' % (self.proxy_user, self.proxy_pass)
                credentials = base64.encodestring(credentials).strip()
                headers.append('Proxy-Authorization: Basic %s' % credentials)
        else:
            headers.append('Connection: Keep-Alive')
        headers.append('\r\n')
        headers = '\r\n'.join(headers)
        return('%s%s' % (headers, httpbody))

    def parse_http_message(self, message):
        """
        Split http message into a tuple:
          - (statusline - list of e.g. ['HTTP/1.1', '200', 'OK'],
          - headers - dictionary of headers e.g. {'Content-Length': '604',
                      'Content-Type': 'text/xml; charset=utf-8'},
          - httpbody - string with http body)
          - http_rest - what is left in the message after a full HTTP header + body
        """
        splitted = message.split('\r\n\r\n')
        if len(splitted) < 2:
            # no complete http message. Keep filling the buffer until we find one
            buffer_rest = message
            return ('', '', '', buffer_rest)
        else:
            (header, httpbody)  = splitted[:2]
            header = header.replace('\r', '')
            header = header.lstrip('\n')
            header = header.split('\n')
            statusline = header[0].split(' ', 2)
            header = header[1:]
            headers = {}
            for dummy in header:
                row = dummy.split(' ', 1)
                headers[row[0][:-1]] = row[1]
            body_size = headers['Content-Length']
            rest_splitted = splitted[2:]
            while (len(httpbody) < body_size) and rest_splitted:
                # Complete httpbody until it has the announced size
                httpbody = '\n\n'.join([httpbody, rest_splitted.pop(0)])
            buffer_rest = "\n\n".join(rest_splitted)
            return (statusline, headers, httpbody, buffer_rest)


class NonBlockingHTTPBOSH(NonBlockingHTTP):
    """
    Class for BOSH HTTP connections. Slightly redefines HTTP transport by
    calling bosh bodytag generating callback before putting data on wire
    """

    def set_stanza_build_cb(self, build_cb):
        self.build_cb = build_cb

    def _do_send(self):
        if self.state == PROXY_CONNECTING:
            NonBlockingTCP._do_send(self)
            return
        if not self.sendbuff:
            stanza = self.build_cb(socket=self)
            stanza = self.encode_stanza(stanza)
            stanza = self.build_http_message(httpbody=stanza)
            self.sendbuff = stanza
        NonBlockingTCP._do_send(self)