#!/usr/bin/python
#-*- coding: utf-8 -*-

# SAT plugin for managing xep-0065

# Copyright (C)
# 2002, 2003, 2004   Dave Smith (dizzyd@jabber.org)
# 2007, 2008         Fabio Forno (xmpp:ff@jabber.bluendo.com)
# 2009, 2010, 2011, 2012, 2013, 2014 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 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 Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# --

# This program is based on proxy65 (http://code.google.com/p/proxy65),
# originaly written by David Smith and modified by Fabio Forno.
# It is sublicensed under AGPL v3 (or any later version) as allowed by the original
# license.

# --

# Here is a copy of the original license:

# Copyright (C)
# 2002-2004   Dave Smith (dizzyd@jabber.org)
# 2007-2008   Fabio Forno (xmpp:ff@jabber.bluendo.com)

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

from sat.core.i18n import _
from logging import debug, info, warning, error
from twisted.internet import protocol, reactor
from twisted.internet import error as jab_error
from twisted.words.protocols.jabber import jid, client as jabber_client
from twisted.protocols.basic import FileSender
from twisted.words.xish import domish
from twisted.web.client import getPage
from sat.core.exceptions import ProfileNotInCacheError
import struct
import hashlib

from zope.interface import implements

try:
    from twisted.words.protocols.xmlstream import XMPPHandler
except ImportError:
    from wokkel.subprotocols import XMPPHandler

from wokkel import disco, iwokkel

IQ_SET = '/iq[@type="set"]'
NS_BS = 'http://jabber.org/protocol/bytestreams'
BS_REQUEST = IQ_SET + '/query[@xmlns="' + NS_BS + '"]'
TIMEOUT = 60  # timeout for workflow

PLUGIN_INFO = {
    "name": "XEP 0065 Plugin",
    "import_name": "XEP-0065",
    "type": "XEP",
    "protocols": ["XEP-0065"],
    "main": "XEP_0065",
    "handler": "yes",
    "description": _("""Implementation of SOCKS5 Bytestreams""")
}

STATE_INITIAL = 0
STATE_AUTH = 1
STATE_REQUEST = 2
STATE_READY = 3
STATE_AUTH_USERPASS = 4
STATE_TARGET_INITIAL = 5
STATE_TARGET_AUTH = 6
STATE_TARGET_REQUEST = 7
STATE_TARGET_READY = 8
STATE_LAST = 9

STATE_CONNECT_PENDING = STATE_LAST + 1

SOCKS5_VER = 0x05

ADDR_IPV4 = 0x01
ADDR_DOMAINNAME = 0x03
ADDR_IPV6 = 0x04

CMD_CONNECT = 0x01
CMD_BIND = 0x02
CMD_UDPASSOC = 0x03

AUTHMECH_ANON = 0x00
AUTHMECH_USERPASS = 0x02
AUTHMECH_INVALID = 0xFF

REPLY_SUCCESS = 0x00
REPLY_GENERAL_FAILUR = 0x01
REPLY_CONN_NOT_ALLOWED = 0x02
REPLY_NETWORK_UNREACHABLE = 0x03
REPLY_HOST_UNREACHABLE = 0x04
REPLY_CONN_REFUSED = 0x05
REPLY_TTL_EXPIRED = 0x06
REPLY_CMD_NOT_SUPPORTED = 0x07
REPLY_ADDR_NOT_SUPPORTED = 0x08


def calculateHash(from_jid, to_jid, sid):
    """Calculate SHA1 Hash according to XEP-0065
    @param from_jid: jid of the requester
    @param to_jid: jid of the target
    @param sid: session id
    @return: hash (string)"""
    return hashlib.sha1((sid + from_jid.full() + to_jid.full()).encode('utf-8')).hexdigest()


class SOCKSv5(protocol.Protocol, FileSender):
    def __init__(self):
        debug(_("Protocol init"))
        self.state = STATE_INITIAL
        self.buf = ""
        self.supportedAuthMechs = [AUTHMECH_ANON]
        self.supportedAddrs = [ADDR_DOMAINNAME]
        self.enabledCommands = [CMD_CONNECT]
        self.peersock = None
        self.addressType = 0
        self.requestType = 0

    def _startNegotiation(self):
        debug("_startNegotiation")
        self.state = STATE_TARGET_AUTH
        self.transport.write(struct.pack('!3B', SOCKS5_VER, 1, AUTHMECH_ANON))

    def _parseNegotiation(self):
        debug("_parseNegotiation")
        try:
            # Parse out data
            ver, nmethod = struct.unpack('!BB', self.buf[:2])
            methods = struct.unpack('%dB' % nmethod, self.buf[2:nmethod + 2])

            # Ensure version is correct
            if ver != 5:
                self.transport.write(struct.pack('!BB', SOCKS5_VER, AUTHMECH_INVALID))
                self.transport.loseConnection()
                return

            # Trim off front of the buffer
            self.buf = self.buf[nmethod + 2:]

            # Check for supported auth mechs
            for m in self.supportedAuthMechs:
                if m in methods:
                    # Update internal state, according to selected method
                    if m == AUTHMECH_ANON:
                        self.state = STATE_REQUEST
                    elif m == AUTHMECH_USERPASS:
                        self.state = STATE_AUTH_USERPASS
                    # Complete negotiation w/ this method
                    self.transport.write(struct.pack('!BB', SOCKS5_VER, m))
                    return

            # No supported mechs found, notify client and close the connection
            self.transport.write(struct.pack('!BB', SOCKS5_VER, AUTHMECH_INVALID))
            self.transport.loseConnection()
        except struct.error:
            pass

    def _parseUserPass(self):
        debug("_parseUserPass")
        try:
            # Parse out data
            ver, ulen = struct.unpack('BB', self.buf[:2])
            uname, = struct.unpack('%ds' % ulen, self.buf[2:ulen + 2])
            plen, = struct.unpack('B', self.buf[ulen + 2])
            password, = struct.unpack('%ds' % plen, self.buf[ulen + 3:ulen + 3 + plen])
            # Trim off fron of the buffer
            self.buf = self.buf[3 + ulen + plen:]
            # Fire event to authenticate user
            if self.authenticateUserPass(uname, password):
                # Signal success
                self.state = STATE_REQUEST
                self.transport.write(struct.pack('!BB', SOCKS5_VER, 0x00))
            else:
                # Signal failure
                self.transport.write(struct.pack('!BB', SOCKS5_VER, 0x01))
                self.transport.loseConnection()
        except struct.error:
            pass

    def sendErrorReply(self, errorcode):
        debug("sendErrorReply")
        # Any other address types are not supported
        result = struct.pack('!BBBBIH', SOCKS5_VER, errorcode, 0, 1, 0, 0)
        self.transport.write(result)
        self.transport.loseConnection()

    def _parseRequest(self):
        debug("_parseRequest")
        try:
            # Parse out data and trim buffer accordingly
            ver, cmd, rsvd, self.addressType = struct.unpack('!BBBB', self.buf[:4])

            # Ensure we actually support the requested address type
            if self.addressType not in self.supportedAddrs:
                self.sendErrorReply(REPLY_ADDR_NOT_SUPPORTED)
                return

            # Deal with addresses
            if self.addressType == ADDR_IPV4:
                addr, port = struct.unpack('!IH', self.buf[4:10])
                self.buf = self.buf[10:]
            elif self.addressType == ADDR_DOMAINNAME:
                nlen = ord(self.buf[4])
                addr, port = struct.unpack('!%dsH' % nlen, self.buf[5:])
                self.buf = self.buf[7 + len(addr):]
            else:
                # Any other address types are not supported
                self.sendErrorReply(REPLY_ADDR_NOT_SUPPORTED)
                return

            # Ensure command is supported
            if cmd not in self.enabledCommands:
                # Send a not supported error
                self.sendErrorReply(REPLY_CMD_NOT_SUPPORTED)
                return

            # Process the command
            if cmd == CMD_CONNECT:
                self.connectRequested(addr, port)
            elif cmd == CMD_BIND:
                self.bindRequested(addr, port)
            else:
                # Any other command is not supported
                self.sendErrorReply(REPLY_CMD_NOT_SUPPORTED)

        except struct.error:
            return None

    def _makeRequest(self):
        debug("_makeRequest")
        self.state = STATE_TARGET_REQUEST
        sha1 = calculateHash(self.data["from"], self.data["to"], self.sid)
        request = struct.pack('!5B%dsH' % len(sha1), SOCKS5_VER, CMD_CONNECT, 0, ADDR_DOMAINNAME, len(sha1), sha1, 0)
        self.transport.write(request)

    def _parseRequestReply(self):
        debug("_parseRequestReply")
        try:
            ver, rep, rsvd, self.addressType = struct.unpack('!BBBB', self.buf[:4])
            # Ensure we actually support the requested address type
            if self.addressType not in self.supportedAddrs:
                self.sendErrorReply(REPLY_ADDR_NOT_SUPPORTED)
                return

            # Deal with addresses
            if self.addressType == ADDR_IPV4:
                addr, port = struct.unpack('!IH', self.buf[4:10])
                self.buf = self.buf[10:]
            elif self.addressType == ADDR_DOMAINNAME:
                nlen = ord(self.buf[4])
                addr, port = struct.unpack('!%dsH' % nlen, self.buf[5:])
                self.buf = self.buf[7 + len(addr):]
            else:
                # Any other address types are not supported
                self.sendErrorReply(REPLY_ADDR_NOT_SUPPORTED)
                return

            # Ensure reply is OK
            if rep != REPLY_SUCCESS:
                self.loseConnection()
                return

            if self.factory.proxy:
                self.state = STATE_READY
                self.factory.activateCb(self.sid, self.factory.iq_id, self.startTransfer, self.profile)
            else:
                self.state = STATE_TARGET_READY
                self.factory.activateCb(self.sid, self.factory.iq_id, self.profile)

        except struct.error:
            return None

    def connectionMade(self):
        debug("connectionMade (mode = %s)" % "requester" if isinstance(self.factory, Socks5ServerFactory) else "target")

        if isinstance(self.factory, Socks5ClientFactory):
            self.sid = self.factory.sid
            self.profile = self.factory.profile
            self.data = self.factory.data
            self.state = STATE_TARGET_INITIAL
            self._startNegotiation()

    def connectRequested(self, addr, port):
        debug("connectRequested")

        # Check that this session is expected
        if addr not in self.factory.hash_sid_map:
            #no: we refuse it
            self.sendErrorReply(REPLY_CONN_REFUSED)
            return
        self.sid, self.profile = self.factory.hash_sid_map[addr]
        client = self.factory.host.getClient(self.profile)
        client.xep_0065_current_stream[self.sid]["start_transfer_cb"] = self.startTransfer
        self.connectCompleted(addr, 0)
        self.transport.stopReading()

    def startTransfer(self, file_obj):
        """Callback called when the result iq is received"""
        d = self.beginFileTransfer(file_obj, self.transport)
        d.addCallback(self.fileTransfered)

    def fileTransfered(self, d):
        info(_("File transfer completed, closing connection"))
        self.transport.loseConnection()
        self.factory.finishedCb(self.sid, True, self.profile)

    def connectCompleted(self, remotehost, remoteport):
        debug("connectCompleted")
        if self.addressType == ADDR_IPV4:
            result = struct.pack('!BBBBIH', SOCKS5_VER, REPLY_SUCCESS, 0, 1, remotehost, remoteport)
        elif self.addressType == ADDR_DOMAINNAME:
            result = struct.pack('!BBBBB%dsH' % len(remotehost), SOCKS5_VER, REPLY_SUCCESS, 0,
                                 ADDR_DOMAINNAME, len(remotehost), remotehost, remoteport)
        self.transport.write(result)
        self.state = STATE_READY

    def bindRequested(self, addr, port):
        pass

    def authenticateUserPass(self, user, passwd):
        debug("User/pass: %s/%s", user, passwd)
        return True

    def dataReceived(self, buf):
        if self.state == STATE_TARGET_READY:
            self.data["file_obj"].write(buf)
            return

        self.buf = self.buf + buf
        if self.state == STATE_INITIAL:
            self._parseNegotiation()
        if self.state == STATE_AUTH_USERPASS:
            self._parseUserPass()
        if self.state == STATE_REQUEST:
            self._parseRequest()
        if self.state == STATE_TARGET_AUTH:
            ver, method = struct.unpack('!BB', buf)
            self.buf = self.buf[2:]
            if ver != SOCKS5_VER or method != AUTHMECH_ANON:
                self.transport.loseConnection()
            else:
                self._makeRequest()
        if self.state == STATE_TARGET_REQUEST:
            self._parseRequestReply()

    def clientConnectionLost(self, reason):
        debug("clientConnectionLost")
        self.transport.loseConnection()

    def connectionLost(self, reason):
        debug("connectionLost")
        if self.state != STATE_CONNECT_PENDING:
            self.transport.unregisterProducer()
            if self.peersock is not None:
                self.peersock.peersock = None
                self.peersock.transport.unregisterProducer()
                self.peersock = None


class Socks5ServerFactory(protocol.ServerFactory):
    protocol = SOCKSv5

    def __init__(self, host, hash_sid_map, finishedCb):
        self.host = host
        self.hash_sid_map = hash_sid_map
        self.finishedCb = finishedCb

    def startedConnecting(self, connector):
        debug(_("Socks 5 server connection started"))

    def clientConnectionLost(self, connector, reason):
        debug(_("Socks 5 server connection lost (reason: %s)"), reason)


class Socks5ClientFactory(protocol.ClientFactory):
    protocol = SOCKSv5

    def __init__(self, current_stream, sid, iq_id, activateCb, finishedCb, proxy=False, profile=None):
        """Init the Client Factory
        @param current_stream: current streams data
        @param sid: Session ID
        @param iq_id: iq id used to initiate the stream
        @param activateCb: method to call to activate the stream
        @param finishedCb: method to call when the stream session is finished
        @param proxy: True if we are connecting throught a proxy (and we are a requester)
        @param profile: %(doc_profile)s"""
        assert(profile)
        self.data = current_stream[sid]
        self.sid = sid
        self.iq_id = iq_id
        self.activateCb = activateCb
        self.finishedCb = finishedCb
        self.proxy = proxy
        self.profile = profile

    def startedConnecting(self, connector):
        debug(_("Socks 5 client connection started"))

    def clientConnectionLost(self, connector, reason):
        debug(_("Socks 5 client connection lost (reason: %s)"), reason)
        self.finishedCb(self.sid, reason.type == jab_error.ConnectionDone, self.profile)  # TODO: really check if the state is actually successful


class XEP_0065(object):

    NAMESPACE = NS_BS

    params = """
    <params>
    <general>
    <category name="File Transfer">
        <param name="IP" value='0.0.0.0' default_cb='yes' type="string" />
        <param name="Port" value="28915" type="string" />
    </category>
    </general>
    <individual>
    <category name="File Transfer">
        <param name="Proxy" value="" type="string" />
        <param name="Proxy host" value="" type="string" />
        <param name="Proxy port" value="" type="string" />
    </category>
    </individual>
    </params>
    """

    def __init__(self, host):
        info(_("Plugin XEP_0065 initialization"))

        #session data
        self.hash_sid_map = {}  # key: hash of the transfer session, value: (session id, profile)

        self.host = host
        debug(_("registering"))
        self.server_factory = Socks5ServerFactory(host, self.hash_sid_map, lambda sid, success, profile: self._killId(sid, success, profile=profile))

        #parameters
        host.memory.updateParams(XEP_0065.params)
        host.memory.setDefault("IP", "File Transfer", self.getExternalIP)
        port = int(self.host.memory.getParamA("Port", "File Transfer"))

        info(_("Launching Socks5 Stream server on port %d"), port)
        reactor.listenTCP(port, self.server_factory)

    def getHandler(self, profile):
        return XEP_0065_handler(self)

    def profileConnected(self, profile):
        client = self.host.getClient(profile)
        client.xep_0065_current_stream = {}  # key: stream_id, value: data(dict)

    def getExternalIP(self):
        """Return IP visible from outside, by asking to a website"""
        return getPage("http://www.goffi.org/sat_tools/get_ip.php")

    def getProgress(self, sid, data, profile):
        """Fill data with position of current transfer"""
        client = self.host.getClient(profile)
        try:
            file_obj = client.xep_0065_current_stream[sid]["file_obj"]
            data["position"] = str(file_obj.tell())
            data["size"] = str(client.xep_0065_current_stream[sid]["size"])
        except:
            pass

    def _timeOut(self, sid, profile):
        """Delecte current_stream id, called after timeout
        @param id: id of client.xep_0065_current_stream"""
        info(_("Socks5 Bytestream: TimeOut reached for id %(sid)s [%(profile)s]")
             % {"sid": sid, "profile": profile})
        self._killId(sid, False, "TIMEOUT", profile)

    def _killId(self, sid, success=False, failure_reason="UNKNOWN", profile=None):
        """Delete an current_stream id, clean up associated observers
        @param sid: id of client.xep_0065_current_stream"""
        assert(profile)
        client = self.host.getClient(profile)
        if sid not in client.xep_0065_current_stream:
            warning(_("kill id called on a non existant id"))
            return
        if "observer_cb" in client.xep_0065_current_stream[sid]:
            xmlstream = client.xep_0065_current_stream[sid]["xmlstream"]
            xmlstream.removeObserver(client.xep_0065_current_stream[sid]["event_data"], client.xep_0065_current_stream[sid]["observer_cb"])
        if client.xep_0065_current_stream[sid]['timer'].active():
            client.xep_0065_current_stream[sid]['timer'].cancel()
        if "size" in client.xep_0065_current_stream[sid]:
            self.host.removeProgressCB(sid, profile)

        file_obj = client.xep_0065_current_stream[sid]['file_obj']
        success_cb = client.xep_0065_current_stream[sid]['success_cb']
        failure_cb = client.xep_0065_current_stream[sid]['failure_cb']

        session_hash = client.xep_0065_current_stream[sid].get('hash')
        del client.xep_0065_current_stream[sid]
        if session_hash in self.hash_sid_map:
            #FIXME: check that self.hash_sid_map is correctly cleaned in all cases (timeout, normal flow, etc).
            del self.hash_sid_map[session_hash]

        if success:
            success_cb(sid, file_obj, NS_BS, profile)
        else:
            failure_cb(sid, file_obj, NS_BS, failure_reason, profile)

    def startStream(self, file_obj, to_jid, sid, length, successCb, failureCb, size=None, profile=None):
        """Launch the stream workflow
        @param file_obj: file_obj to send
        @param to_jid: JID of the recipient
        @param sid: Stream session id
        @param length: number of byte to send, or None to send until the end
        @param successCb: method to call when stream successfuly finished
        @param failureCb: method to call when something goes wrong
        @param profile: %(doc_profile)s"""
        assert(profile)
        client = self.host.getClient(profile)

        if length is not None:
            error(_('stream length not managed yet'))
            return

        profile_jid = client.jid
        xmlstream = client.xmlstream

        data = client.xep_0065_current_stream[sid] = {}
        data["timer"] = reactor.callLater(TIMEOUT, self._timeOut, sid, profile)
        data["file_obj"] = file_obj
        data["from"] = profile_jid
        data["to"] = to_jid
        data["success_cb"] = successCb
        data["failure_cb"] = failureCb
        data["xmlstream"] = xmlstream
        data["hash"] = calculateHash(profile_jid, to_jid, sid)
        self.hash_sid_map[data["hash"]] = (sid, profile)
        if size:
            data["size"] = size
            self.host.registerProgressCB(sid, self.getProgress, profile)
        iq_elt = jabber_client.IQ(xmlstream, 'set')
        iq_elt["from"] = profile_jid.full()
        iq_elt["to"] = to_jid.full()
        query_elt = iq_elt.addElement('query', NS_BS)
        query_elt['mode'] = 'tcp'
        query_elt['sid'] = sid
        #first streamhost: direct connection
        streamhost = query_elt.addElement('streamhost')
        streamhost['host'] = self.host.memory.getParamA("IP", "File Transfer")
        streamhost['port'] = self.host.memory.getParamA("Port", "File Transfer")
        streamhost['jid'] = profile_jid.full()

        #second streamhost: mediated connection, using proxy
        streamhost = query_elt.addElement('streamhost')
        streamhost['host'] = self.host.memory.getParamA("Proxy host", "File Transfer", profile_key=profile)
        streamhost['port'] = self.host.memory.getParamA("Proxy port", "File Transfer", profile_key=profile)
        streamhost['jid'] = self.host.memory.getParamA("Proxy", "File Transfer", profile_key=profile)

        iq_elt.addCallback(self.iqResult, sid, profile)
        iq_elt.send()

    def iqResult(self, sid, profile, iq_elt):
        """Called when the result of open iq is received"""
        if iq_elt["type"] == "error":
            warning(_("Transfer failed"))
            return
        client = self.host.getClient(profile)
        try:
            data = client.xep_0065_current_stream[sid]
            file_obj = data["file_obj"]
            timer = data["timer"]
        except KeyError:
            error(_("Internal error, can't do transfer"))
            return

        if timer.active():
            timer.cancel()

        profile_jid, xmlstream = self.host.getJidNStream(profile)
        query_elt = iq_elt.firstChildElement()
        streamhost_elts = filter(lambda elt: elt.name == 'streamhost-used', query_elt.elements())
        if not streamhost_elts:
            warning(_("No streamhost found in stream query"))
            return

        streamhost_jid = streamhost_elts[0]['jid']
        if streamhost_jid != profile_jid.full():
            debug(_("A proxy server is used"))
            proxy_host = self.host.memory.getParamA("Proxy host", "File Transfer", profile_key=profile)
            proxy_port = self.host.memory.getParamA("Proxy port", "File Transfer", profile_key=profile)
            proxy_jid = self.host.memory.getParamA("Proxy", "File Transfer", profile_key=profile)
            if proxy_jid != streamhost_jid:
                warning(_("Proxy jid is not the same as in parameters, this should not happen"))
                return
            factory = Socks5ClientFactory(client.xep_0065_current_stream, sid, None, self.activateProxyStream, lambda sid, success, profile: self._killId(sid, success, profile=profile), True, profile)
            reactor.connectTCP(proxy_host, int(proxy_port), factory)
        else:
            data["start_transfer_cb"](file_obj)  # We now activate the stream

    def activateProxyStream(self, sid, iq_id, start_transfer_cb, profile):
        debug(_("activating stream"))
        client = self.host.getClient(profile)
        data = client.xep_0065_current_stream[sid]
        profile_jid, xmlstream = self.host.getJidNStream(profile)

        iq_elt = client.IQ(xmlstream, 'set')
        iq_elt["from"] = profile_jid.full()
        iq_elt["to"] = self.host.memory.getParamA("Proxy", "File Transfer", profile_key=profile)
        query_elt = iq_elt.addElement('query', NS_BS)
        query_elt['sid'] = sid
        query_elt.addElement('activate', content=data['to'].full())
        iq_elt.addCallback(self.proxyResult, sid, start_transfer_cb, data['file_obj'])
        iq_elt.send()

    def proxyResult(self, sid, start_transfer_cb, file_obj, iq_elt):
        if iq_elt['type'] == 'error':
            warning(_("Can't activate the proxy stream"))
            return
        else:
            start_transfer_cb(file_obj)

    def prepareToReceive(self, from_jid, sid, file_obj, size, success_cb, failure_cb, profile):
        """Called when a bytestream is imminent
        @param from_jid: jid of the sender
        @param sid: Stream id
        @param file_obj: File object where data will be written
        @param size: full size of the data, or None if unknown
        @param success_cb: method to call when successfuly finished
        @param failure_cb: method to call when something goes wrong
        @param profile: %(doc_profile)s"""
        client = self.host.getClient(profile)
        data = client.xep_0065_current_stream[sid] = {}
        data["from"] = from_jid
        data["file_obj"] = file_obj
        data["seq"] = -1
        if size:
            data["size"] = size
            self.host.registerProgressCB(sid, self.getProgress, profile)
        data["timer"] = reactor.callLater(TIMEOUT, self._timeOut, sid, profile)
        data["success_cb"] = success_cb
        data["failure_cb"] = failure_cb

    def streamQuery(self, iq_elt, profile):
        """Get file using byte stream"""
        debug(_("BS stream query"))
        client = self.host.getClient(profile)

        if not client:
            raise ProfileNotInCacheError

        xmlstream = client.xmlstream

        iq_elt.handled = True
        query_elt = iq_elt.firstChildElement()
        sid = query_elt.getAttribute("sid")
        streamhost_elts = filter(lambda elt: elt.name == 'streamhost', query_elt.elements())

        if not sid in client.xep_0065_current_stream:
            warning(_("Ignoring unexpected BS transfer: %s" % sid))
            self.sendNotAcceptableError(iq_elt['id'], iq_elt['from'], xmlstream)
            return

        client.xep_0065_current_stream[sid]['timer'].cancel()
        client.xep_0065_current_stream[sid]["to"] = jid.JID(iq_elt["to"])
        client.xep_0065_current_stream[sid]["xmlstream"] = xmlstream

        if not streamhost_elts:
            warning(_("No streamhost found in stream query %s" % sid))
            self.sendBadRequestError(iq_elt['id'], iq_elt['from'], xmlstream)
            return

        streamhost_elt = streamhost_elts[0]  # TODO: manage several streamhost elements case
        sh_host = streamhost_elt.getAttribute("host")
        sh_port = streamhost_elt.getAttribute("port")
        sh_jid = streamhost_elt.getAttribute("jid")
        if not sh_host or not sh_port or not sh_jid:
            warning(_("incomplete streamhost element"))
            self.sendBadRequestError(iq_elt['id'], iq_elt['from'], xmlstream)
            return

        client.xep_0065_current_stream[sid]["streamhost"] = (sh_host, sh_port, sh_jid)

        info(_("Stream proposed: host=[%(host)s] port=[%(port)s]") % {'host': sh_host, 'port': sh_port})
        factory = Socks5ClientFactory(client.xep_0065_current_stream, sid, iq_elt["id"], self.activateStream, lambda sid, success, profile: self._killId(sid, success, profile=profile), profile=profile)
        reactor.connectTCP(sh_host, int(sh_port), factory)

    def activateStream(self, sid, iq_id, profile):
        client = self.host.getClient(profile)
        debug(_("activating stream"))
        result = domish.Element((None, 'iq'))
        data = client.xep_0065_current_stream[sid]
        result['type'] = 'result'
        result['id'] = iq_id
        result['from'] = data["to"].full()
        result['to'] = data["from"].full()
        query = result.addElement('query', NS_BS)
        query['sid'] = sid
        streamhost = query.addElement('streamhost-used')
        streamhost['jid'] = data["streamhost"][2]
        data["xmlstream"].send(result)

    def sendNotAcceptableError(self, iq_id, to_jid, xmlstream):
        """Not acceptable error used when the stream is not expected or something is going wrong
        @param iq_id: IQ id
        @param to_jid: addressee
        @param xmlstream: XML stream to use to send the error"""
        result = domish.Element((None, 'iq'))
        result['type'] = 'result'
        result['id'] = iq_id
        result['to'] = to_jid
        error_el = result.addElement('error')
        error_el['type'] = 'modify'
        error_el.addElement(('urn:ietf:params:xml:ns:xmpp-stanzas', 'not-acceptable'))
        xmlstream.send(result)

    def sendBadRequestError(self, iq_id, to_jid, xmlstream):
        """Not acceptable error used when the stream is not expected or something is going wrong
        @param iq_id: IQ id
        @param to_jid: addressee
        @param xmlstream: XML stream to use to send the error"""
        result = domish.Element((None, 'iq'))
        result['type'] = 'result'
        result['id'] = iq_id
        result['to'] = to_jid
        error_el = result.addElement('error')
        error_el['type'] = 'cancel'
        error_el.addElement(('urn:ietf:params:xml:ns:xmpp-stanzas', 'bad-request'))
        xmlstream.send(result)


class XEP_0065_handler(XMPPHandler):
    implements(iwokkel.IDisco)

    def __init__(self, plugin_parent):
        self.plugin_parent = plugin_parent
        self.host = plugin_parent.host

    def _proxyDataResult(self, iq_elt):
        """Called with the informations about proxy according to XEP-0065 #4
        Params should be filled with these infos"""
        if iq_elt["type"] == "error":
            warning(_("Can't determine proxy informations"))
            return
        query_elt = iq_elt.firstChildElement()
        if query_elt.name != "query":
            warning(_("Bad answer received from proxy"))
            return
        streamhost_elts = filter(lambda elt: elt.name == 'streamhost', query_elt.elements())
        if not streamhost_elts:
            warning(_("No streamhost found in stream query"))
            return
        if len(streamhost_elts) != 1:
            warning(_("Multiple streamhost elements in proxy not managed, keeping only the first one"))
        streamhost_elt = streamhost_elts[0]
        self.host.memory.setParam("Proxy", streamhost_elt.getAttribute("jid", ""),
                                  "File Transfer", profile_key=self.parent.profile)
        self.host.memory.setParam("Proxy host", streamhost_elt.getAttribute("host", ""),
                                  "File Transfer", profile_key=self.parent.profile)
        self.host.memory.setParam("Proxy port", streamhost_elt.getAttribute("port", ""),
                                          "File Transfer", profile_key=self.parent.profile)

    def connectionInitialized(self):
        def after_init(ignore):
            proxy_ent = self.host.memory.getServerServiceEntity("proxy", "bytestreams", profile=self.parent.profile)
            if not proxy_ent:
                debug(_("No proxy found on this server"))
                return
            iq_elt = jabber_client.IQ(self.parent.xmlstream, 'get')
            iq_elt["to"] = proxy_ent.full()
            iq_elt.addElement('query', NS_BS)
            iq_elt.addCallback(self._proxyDataResult)
            iq_elt.send()

        self.xmlstream.addObserver(BS_REQUEST, self.plugin_parent.streamQuery, profile=self.parent.profile)
        proxy = self.host.memory.getParamA("Proxy", "File Transfer", profile_key=self.parent.profile)
        if not proxy:
            self.parent.client_initialized.addCallback(after_init)

    def getDiscoInfo(self, requestor, target, nodeIdentifier=''):
        return [disco.DiscoFeature(NS_BS)]

    def getDiscoItems(self, requestor, target, nodeIdentifier=''):
        return []