"""TLS Lite + asyncore."""





import asyncore

from gdata.tlslite.TLSConnection import TLSConnection

from AsyncStateMachine import AsyncStateMachine





class TLSAsyncDispatcherMixIn(AsyncStateMachine):

    """This class can be "mixed in" with an

    L{asyncore.dispatcher} to add TLS support.



    This class essentially sits between the dispatcher and the select

    loop, intercepting events and only calling the dispatcher when

    applicable.



    In the case of handle_read(), a read operation will be activated,

    and when it completes, the bytes will be placed in a buffer where

    the dispatcher can retrieve them by calling recv(), and the

    dispatcher's handle_read() will be called.



    In the case of handle_write(), the dispatcher's handle_write() will

    be called, and when it calls send(), a write operation will be

    activated.



    To use this class, you must combine it with an asyncore.dispatcher,

    and pass in a handshake operation with setServerHandshakeOp().



    Below is an example of using this class with medusa.  This class is

    mixed in with http_channel to create http_tls_channel.  Note:

     1. the mix-in is listed first in the inheritance list



     2. the input buffer size must be at least 16K, otherwise the

       dispatcher might not read all the bytes from the TLS layer,

       leaving some bytes in limbo.



     3. IE seems to have a problem receiving a whole HTTP response in a

     single TLS record, so HTML pages containing '\\r\\n\\r\\n' won't

     be displayed on IE.



    Add the following text into 'start_medusa.py', in the 'HTTP Server'

    section::



        from tlslite.api import *

        s = open("./serverX509Cert.pem").read()

        x509 = X509()

        x509.parse(s)

        certChain = X509CertChain([x509])



        s = open("./serverX509Key.pem").read()

        privateKey = parsePEMKey(s, private=True)



        class http_tls_channel(TLSAsyncDispatcherMixIn,

                               http_server.http_channel):

            ac_in_buffer_size = 16384



            def __init__ (self, server, conn, addr):

                http_server.http_channel.__init__(self, server, conn, addr)

                TLSAsyncDispatcherMixIn.__init__(self, conn)

                self.tlsConnection.ignoreAbruptClose = True

                self.setServerHandshakeOp(certChain=certChain,

                                          privateKey=privateKey)



        hs.channel_class = http_tls_channel



    If the TLS layer raises an exception, the exception will be caught

    in asyncore.dispatcher, which will call close() on this class.  The

    TLS layer always closes the TLS connection before raising an

    exception, so the close operation will complete right away, causing

    asyncore.dispatcher.close() to be called, which closes the socket

    and removes this instance from the asyncore loop.



    """





    def __init__(self, sock=None):

        AsyncStateMachine.__init__(self)



        if sock:

            self.tlsConnection = TLSConnection(sock)



        #Calculate the sibling I'm being mixed in with.

        #This is necessary since we override functions

        #like readable(), handle_read(), etc., but we

        #also want to call the sibling's versions.

        for cl in self.__class__.__bases__:

            if cl != TLSAsyncDispatcherMixIn and cl != AsyncStateMachine:

                self.siblingClass = cl

                break

        else:

            raise AssertionError()



    def readable(self):

        result = self.wantsReadEvent()

        if result != None:

            return result

        return self.siblingClass.readable(self)



    def writable(self):

        result = self.wantsWriteEvent()

        if result != None:

            return result

        return self.siblingClass.writable(self)



    def handle_read(self):

        self.inReadEvent()



    def handle_write(self):

        self.inWriteEvent()



    def outConnectEvent(self):

        self.siblingClass.handle_connect(self)



    def outCloseEvent(self):

        asyncore.dispatcher.close(self)



    def outReadEvent(self, readBuffer):

        self.readBuffer = readBuffer

        self.siblingClass.handle_read(self)



    def outWriteEvent(self):

        self.siblingClass.handle_write(self)



    def recv(self, bufferSize=16384):

        if bufferSize < 16384 or self.readBuffer == None:

            raise AssertionError()

        returnValue = self.readBuffer

        self.readBuffer = None

        return returnValue



    def send(self, writeBuffer):

        self.setWriteOp(writeBuffer)

        return len(writeBuffer)



    def close(self):

        if hasattr(self, "tlsConnection"):

            self.setCloseOp()

        else:

            asyncore.dispatcher.close(self)