##   auth.py
##
##   Copyright (C) 2003-2005 Alexey "Snake" Nezhdanov
##
##   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.

# $Id: auth.py,v 1.41 2008/09/13 21:45:21 normanr Exp $

"""
Provides library with all Non-SASL and SASL authentication mechanisms.
Can be used both for client and transport authentication.
"""

from .protocol import *
from .client import PlugIn
import hashlib,base64,random,re,os,hmac
from . import dispatcher

def HH(some): return hashlib.md5(some).hexdigest()
def H(some): return hashlib.md5(some).digest()
def C(some): return ':'.join(some)

class NonSASL(PlugIn):
    """ Implements old Non-SASL (JEP-0078) authentication used in jabberd1.4 and transport authentication."""
    def __init__(self,user,password,resource):
        """ Caches username, password and resource for auth. """
        PlugIn.__init__(self)
        self.DBG_LINE='gen_auth'
        self.user=user
        self.password=password
        self.resource=resource

    def plugin(self,owner):
        """ Determine the best auth method (digest/0k/plain) and use it for auth.
            Returns used method name on success. Used internally. """
        if not self.resource: return self.authComponent(owner)
        self.DEBUG('Querying server about possible auth methods','start')
        resp=owner.Dispatcher.SendAndWaitForResponse(Iq('get',NS_AUTH,payload=[Node('username',payload=[self.user])]))
        if not isResultNode(resp):
            self.DEBUG('No result node arrived! Aborting...','error')
            return
        iq=Iq(typ='set',node=resp)
        query=iq.getTag('query')
        query.setTagData('username',self.user)
        query.setTagData('resource',self.resource)

        if query.getTag('digest'):
            self.DEBUG("Performing digest authentication",'ok')
            query.setTagData('digest',sha.new(owner.Dispatcher.Stream._document_attrs['id']+self.password).hexdigest())
            if query.getTag('password'): query.delChild('password')
            method='digest'
        elif query.getTag('token'):
            token=query.getTagData('token')
            seq=query.getTagData('sequence')
            self.DEBUG("Performing zero-k authentication",'ok')
            hash = sha.new(sha.new(self.password).hexdigest()+token).hexdigest()
            for foo in range(int(seq)): hash = sha.new(hash).hexdigest()
            query.setTagData('hash',hash)
            method='0k'
        else:
            self.DEBUG("Sequre methods unsupported, performing plain text authentication",'warn')
            query.setTagData('password',self.password)
            method='plain'
        resp=owner.Dispatcher.SendAndWaitForResponse(iq)
        if isResultNode(resp):
            self.DEBUG('Sucessfully authenticated with remove host.','ok')
            owner.User=self.user
            owner.Resource=self.resource
            owner._registered_name=owner.User+'@'+owner.Server+'/'+owner.Resource
            return method
        self.DEBUG('Authentication failed!','error')

    def authComponent(self,owner):
        """ Authenticate component. Send handshake stanza and wait for result. Returns "ok" on success. """
        self.handshake=0
        owner.send(Node(NS_COMPONENT_ACCEPT+' handshake',payload=[sha.new(owner.Dispatcher.Stream._document_attrs['id']+self.password).hexdigest()]))
        owner.RegisterHandler('handshake',self.handshakeHandler,xmlns=NS_COMPONENT_ACCEPT)
        while not self.handshake:
            self.DEBUG("waiting on handshake",'notify')
            owner.Process(1)
        owner._registered_name=self.user
        if self.handshake+1: return 'ok'

    def handshakeHandler(self,disp,stanza):
        """ Handler for registering in dispatcher for accepting transport authentication. """
        if stanza.getName()=='handshake': self.handshake=1
        else: self.handshake=-1

class SASL(PlugIn):
    """ Implements SASL authentication. """
    def __init__(self,username,password):
        PlugIn.__init__(self)
        self.username=username
        self.password=password
        self._scram=None
        self._scram_candidates=[]

    def plugin(self,owner):
        if not ('version' in self._owner.Dispatcher.Stream._document_attrs): self.startsasl='not-supported'
        elif self._owner.Dispatcher.Stream.features:
            try: self.FeaturesHandler(self._owner.Dispatcher,self._owner.Dispatcher.Stream.features)
            except NodeProcessed: pass
        else: self.startsasl=None

    def auth(self):
        """ Start authentication. Result can be obtained via "SASL.startsasl" attribute and will be
            either "success" or "failure". Note that successfull auth will take at least
            two Dispatcher.Process() calls. """
        if self.startsasl: pass
        elif self._owner.Dispatcher.Stream.features:
            try: self.FeaturesHandler(self._owner.Dispatcher,self._owner.Dispatcher.Stream.features)
            except NodeProcessed: pass
        else: self._owner.RegisterHandler('features',self.FeaturesHandler,xmlns=NS_STREAMS)

    def plugout(self):
        """ Remove SASL handlers from owner's dispatcher. Used internally. """
        if ('features' in self._owner.__dict__): self._owner.UnregisterHandler('features',self.FeaturesHandler,xmlns=NS_STREAMS)
        if ('challenge' in self._owner.__dict__): self._owner.UnregisterHandler('challenge',self.SASLHandler,xmlns=NS_SASL)
        if ('failure' in self._owner.__dict__): self._owner.UnregisterHandler('failure',self.SASLHandler,xmlns=NS_SASL)
        if ('success' in self._owner.__dict__): self._owner.UnregisterHandler('success',self.SASLHandler,xmlns=NS_SASL)

    def _scram_hash(self,mechanism):
        """Return hashlib algorithm name for a SCRAM mechanism."""
        if '-SHA-512' in mechanism: return 'sha512'
        if '-SHA-256' in mechanism: return 'sha256'
        return 'sha1'

    def _scram_cb_data(self):
        """Get tls-server-end-point channel binding data (SHA-256 of server cert DER)."""
        try:
            sock=self._owner.Connection._sock
            if hasattr(sock,'getpeercert'):
                cert=sock.getpeercert(binary_form=True)
                if cert: return hashlib.sha256(cert).digest()
        except: pass
        return None

    def _scram_start(self,mechanism,use_cb):
        """Send SCRAM client-first-message (base64-encoded per RFC 5802)."""
        hash_name=self._scram_hash(mechanism)
        if use_cb:
            cb=self._scram_cb_data()
            if not cb:
                self.startsasl='failure'
                self.DEBUG('SCRAM: no channel binding data','error')
                return
            gs2=b'p=tls-server-end-point,,'
        else:
            cb=None
            gs2=b'n,,'
        client_nonce=base64.b64encode(os.urandom(24)).decode('ascii')
        user=(self.username or '').replace('=','=3D').replace(',','=2C')
        client_first_bare='n=%s,r=%s'%(user,client_nonce)
        client_first=gs2+client_first_bare.encode('utf-8')
        payload=base64.b64encode(client_first).decode('ascii')
        node=Node('auth',attrs={'xmlns':NS_SASL,'mechanism':mechanism},payload=[payload])
        self._scram={'hash':hash_name,'gs2':gs2,'nonce':client_nonce,'first_bare':client_first_bare,'cb':cb}
        self.startsasl='in-process'
        self._owner.send(node.__str__())
        raise NodeProcessed

    def _scram_continue(self,data):
        """Handle SCRAM server-first-message challenge."""
        s=self._scram
        hash_name=s['hash']
        server_first=base64.b64decode(data).decode('utf-8')
        parts={}
        for p in server_first.split(','):
            if '=' in p: k,v=p.split('=',1); parts[k]=v
        nonce=parts.get('r','')
        salt_b64=parts.get('s','')
        iters=int(parts.get('i','0'))
        if not nonce.startswith(s['nonce']):
            self.startsasl='failure'; self.DEBUG('SCRAM: nonce mismatch','error'); return
        # c= value is base64(gs2-header-bytes + channel-binding-data)
        if s['cb']:
            c_b64=base64.b64encode(s['gs2']+s['cb']).decode('ascii')
        else:
            c_b64=base64.b64encode(s['gs2']).decode('ascii')
        client_final_noproof='c=%s,r=%s'%(c_b64,nonce)
        authmsg=s['first_bare']+','+server_first+','+client_final_noproof
        salt=base64.b64decode(salt_b64)
        salted=hashlib.pbkdf2_hmac(hash_name,self.password.encode('utf-8'),salt,iters)
        clientKey=hmac.new(salted,b'Client Key',hash_name).digest()
        storedKey=hashlib.new(hash_name,clientKey).digest()
        clientSig=hmac.new(storedKey,authmsg.encode('utf-8'),hash_name).digest()
        clientProof=bytes(a^b for a,b in zip(clientKey,clientSig))
        client_final=client_final_noproof+',p='+base64.b64encode(clientProof).decode('ascii')
        # base64-encode entire client-final-message per RFC 5802
        payload=base64.b64encode(client_final.encode('utf-8')).decode('ascii')
        node=Node('response',attrs={'xmlns':NS_SASL},payload=[payload])
        self._owner.send(node.__str__())
        raise NodeProcessed

    def _scram_build_list(self,mecs):
        """Build prioritized list of SCRAM mechanisms to try."""
        cb=self._scram_cb_data()
        cands=[]
        for mec in ['SCRAM-SHA-512-PLUS','SCRAM-SHA-256-PLUS','SCRAM-SHA-1-PLUS']:
            if mec in mecs and cb: cands.append((mec,True))
        for mec in ['SCRAM-SHA-512','SCRAM-SHA-256','SCRAM-SHA-1']:
            if mec in mecs: cands.append((mec,False))
        return cands

    def _scram_try_next(self):
        """Try next SCRAM mechanism from candidate list."""
        while self._scram_candidates:
            mec,use_cb=self._scram_candidates.pop(0)
            self._scram=None
            try: self._scram_start(mec,use_cb)
            except NodeProcessed: return True
            except: continue
        return False

    def FeaturesHandler(self,conn,feats):
        """ Used to determine if server supports SASL auth. Used internally. """
        if not feats.getTag('mechanisms',namespace=NS_SASL):
            self.startsasl='not-supported'
            self.DEBUG('SASL not supported by server','error')
            return
        mecs=[]
        for mec in feats.getTag('mechanisms',namespace=NS_SASL).getTags('mechanism'):
            mecs.append(mec.getData())
        self._owner.RegisterHandler('challenge',self.SASLHandler,xmlns=NS_SASL)
        self._owner.RegisterHandler('failure',self.SASLHandler,xmlns=NS_SASL)
        self._owner.RegisterHandler('success',self.SASLHandler,xmlns=NS_SASL)
        if "ANONYMOUS" in mecs and self.username == None:
            node=Node('auth',attrs={'xmlns':NS_SASL,'mechanism':'ANONYMOUS'})
            self.startsasl='in-process'
            self._owner.send(node.__str__())
            raise NodeProcessed
        self._scram_candidates=self._scram_build_list(mecs)
        if self._scram_candidates:
            if self._scram_try_next(): return
        if "DIGEST-MD5" in mecs:
            node=Node('auth',attrs={'xmlns':NS_SASL,'mechanism':'DIGEST-MD5'})
        elif "PLAIN" in mecs:
            sasl_data=('%s\x00%s\x00%s'%(self.username+'@'+self._owner.Server,self.username,self.password)).encode('utf-8')
            node=Node('auth',attrs={'xmlns':NS_SASL,'mechanism':'PLAIN'},payload=[base64.encodebytes(sasl_data).replace(b'\r',b'').replace(b'\n',b'').decode('ascii')])
        else:
            self.startsasl='failure'
            self.DEBUG('I can only use DIGEST-MD5 and PLAIN mecanisms.','error')
            return
        self.startsasl='in-process'
        self._owner.send(node.__str__())
        raise NodeProcessed

    def SASLHandler(self,conn,challenge):
        """ Perform next SASL auth step. Used internally. """
        if challenge.getNamespace()!=NS_SASL: return
        if challenge.getName()=='failure':
            self._scram=None
            # Try next SCRAM candidate if available
            if self._scram_candidates:
                self.DEBUG('SCRAM failed, trying next mechanism','warn')
                if self._scram_try_next(): raise NodeProcessed
            self.startsasl='failure'
            try: reason=challenge.getChildren()[0]
            except: reason=challenge
            self.DEBUG('Failed SASL authentification: %s'%reason,'error')
            raise NodeProcessed
        elif challenge.getName()=='success':
            self.startsasl='success'
            self._scram=None
            self.DEBUG('Successfully authenticated with remote server.','ok')
            handlers=self._owner.Dispatcher.dumpHandlers()
            self._owner.Dispatcher.PlugOut()
            dispatcher.Dispatcher().PlugIn(self._owner)
            self._owner.Dispatcher.restoreHandlers(handlers)
            self._owner.User=self.username
            raise NodeProcessed
        if self._scram:
            return self._scram_continue(challenge.getData())
########################################3333
        incoming_data=challenge.getData()
        chal={}
        data=base64.decodebytes(incoming_data)
        self.DEBUG('Got challenge:'+data,'ok')
        for pair in re.findall('(\w+\s*=\s*(?:(?:"[^"]+")|(?:[^,]+)))',data):
            key,value=[x.strip() for x in pair.split('=', 1)]
            if value[:1]=='"' and value[-1:]=='"': value=value[1:-1]
            chal[key]=value
        if ('qop' in chal) and 'auth' in [x.strip() for x in chal['qop'].split(',')]:
            resp={}
            resp['username']=self.username
            resp['realm']=self._owner.Server
            resp['nonce']=chal['nonce']
            cnonce=''
            for i in range(7):
                cnonce+=hex(int(random.random()*65536*4096))[2:]
            resp['cnonce']=cnonce
            resp['nc']=('00000001')
            resp['qop']='auth'
            resp['digest-uri']='xmpp/'+self._owner.Server
            A1=C([H(C([resp['username'],resp['realm'],self.password])),resp['nonce'],resp['cnonce']])
            A2=C(['AUTHENTICATE',resp['digest-uri']])
            response= HH(C([HH(A1),resp['nonce'],resp['nc'],resp['cnonce'],resp['qop'],HH(A2)]))
            resp['response']=response
            resp['charset']='utf-8'
            sasl_data=''
            for key in ['charset','username','realm','nonce','nc','cnonce','digest-uri','response','qop']:
                if key in ['nc','qop','response','charset']: sasl_data+="%s=%s,"%(key,resp[key])
                else: sasl_data+='%s="%s",'%(key,resp[key])
########################################3333
            node=Node('response',attrs={'xmlns':NS_SASL},payload=[base64.encodebytes(sasl_data[:-1]).replace(b'\r',b'').replace(b'\n',b'').decode('ascii')])
            self._owner.send(node.__str__())
        elif ('rspauth' in chal): self._owner.send(Node('response',attrs={'xmlns':NS_SASL}).__str__())
        else:
            self.startsasl='failure'
            self.DEBUG('Failed SASL authentification: unknown challenge','error')
        raise NodeProcessed

class Bind(PlugIn):
    """ Bind some JID to the current connection to allow router know of our location."""
    def __init__(self):
        PlugIn.__init__(self)
        self.DBG_LINE='bind'
        self.bound=None

    def plugin(self,owner):
        """ Start resource binding, if allowed at this time. Used internally. """
        if self._owner.Dispatcher.Stream.features:
            try: self.FeaturesHandler(self._owner.Dispatcher,self._owner.Dispatcher.Stream.features)
            except NodeProcessed: pass
        else: self._owner.RegisterHandler('features',self.FeaturesHandler,xmlns=NS_STREAMS)

    def plugout(self):
        """ Remove Bind handler from owner's dispatcher. Used internally. """
        self._owner.UnregisterHandler('features',self.FeaturesHandler,xmlns=NS_STREAMS)

    def FeaturesHandler(self,conn,feats):
        """ Determine if server supports resource binding and set some internal attributes accordingly. """
        if not feats.getTag('bind',namespace=NS_BIND):
            self.bound='failure'
            self.DEBUG('Server does not requested binding.','error')
            return
        if feats.getTag('session',namespace=NS_SESSION): self.session=1
        else: self.session=-1
        self.bound=[]

    def Bind(self,resource=None):
        """ Perform binding. Use provided resource name or random (if not provided). """
        while self.bound is None and self._owner.Process(1): pass
        if resource: resource=[Node('resource',payload=[resource])]
        else: resource=[]
        resp=self._owner.SendAndWaitForResponse(Protocol('iq',typ='set',payload=[Node('bind',attrs={'xmlns':NS_BIND},payload=resource)]))
        if isResultNode(resp):
            self.bound.append(resp.getTag('bind').getTagData('jid'))
            self.DEBUG('Successfully bound %s.'%self.bound[-1],'ok')
            jid=JID(resp.getTag('bind').getTagData('jid'))
            self._owner.User=jid.getNode()
            self._owner.Resource=jid.getResource()
            resp=self._owner.SendAndWaitForResponse(Protocol('iq',typ='set',payload=[Node('session',attrs={'xmlns':NS_SESSION})]))
            if isResultNode(resp):
                self.DEBUG('Successfully opened session.','ok')
                self.session=1
                return 'ok'
            else:
                self.DEBUG('Session open failed.','error')
                self.session=0
        elif resp: self.DEBUG('Binding failed: %s.'%resp.getTag('error'),'error')
        else:
            self.DEBUG('Binding failed: timeout expired.','error')
            return ''

class ComponentBind(PlugIn):
    """ ComponentBind some JID to the current connection to allow router know of our location."""
    def __init__(self, sasl):
        PlugIn.__init__(self)
        self.DBG_LINE='bind'
        self.bound=None
        self.needsUnregister=None
        self.sasl = sasl

    def plugin(self,owner):
        """ Start resource binding, if allowed at this time. Used internally. """
        if not self.sasl:
            self.bound=[]
            return
        if self._owner.Dispatcher.Stream.features:
            try: self.FeaturesHandler(self._owner.Dispatcher,self._owner.Dispatcher.Stream.features)
            except NodeProcessed: pass
        else:
            self._owner.RegisterHandler('features',self.FeaturesHandler,xmlns=NS_STREAMS)
            self.needsUnregister=1

    def plugout(self):
        """ Remove ComponentBind handler from owner's dispatcher. Used internally. """
        if self.needsUnregister:
            self._owner.UnregisterHandler('features',self.FeaturesHandler,xmlns=NS_STREAMS)

    def FeaturesHandler(self,conn,feats):
        """ Determine if server supports resource binding and set some internal attributes accordingly. """
        if not feats.getTag('bind',namespace=NS_BIND):
            self.bound='failure'
            self.DEBUG('Server does not requested binding.','error')
            return
        if feats.getTag('session',namespace=NS_SESSION): self.session=1
        else: self.session=-1
        self.bound=[]

    def Bind(self,domain=None):
        """ Perform binding. Use provided domain name (if not provided). """
        while self.bound is None and self._owner.Process(1): pass
        if self.sasl:
            xmlns = NS_COMPONENT_1
        else:
            xmlns = None
        self.bindresponse = None
        ttl = dispatcher.DefaultTimeout
        self._owner.RegisterHandler('bind',self.BindHandler,xmlns=xmlns)
        self._owner.send(Protocol('bind',attrs={'name':domain},xmlns=NS_COMPONENT_1))
        while self.bindresponse is None and self._owner.Process(1) and ttl > 0: ttl-=1
        self._owner.UnregisterHandler('bind',self.BindHandler,xmlns=xmlns)
        resp=self.bindresponse
        if resp and resp.getAttr('error'):
            self.DEBUG('Binding failed: %s.'%resp.getAttr('error'),'error')
        elif resp:
            self.DEBUG('Successfully bound.','ok')
            return 'ok'
        else:
            self.DEBUG('Binding failed: timeout expired.','error')
            return ''

    def BindHandler(self,conn,bind):
        self.bindresponse = bind
        pass