tlslite.integration.tlsasyncdispatchermixin module

TLS Lite + asyncore.

class tlslite.integration.tlsasyncdispatchermixin.TLSAsyncDispatcherMixIn(sock=None)

Bases: AsyncStateMachine

This class can be “mixed in” with an 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 ‘rnrn’ won’t be displayed on IE.

Add the following text into ‘start_medusa.py’, in the ‘HTTP Server’ section:

from tlslite import *
s = open("./serverX509Cert.pem").read()
x509 = X509()
x509.parse(s)
cert_chain = 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=cert_chain,
                                  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.

__init__(sock=None)

close()

handle_read()

handle_write()

outCloseEvent()

Called when a close operation completes.

May be overridden in subclass.

outConnectEvent()

Called when a handshake operation completes.

May be overridden in subclass.

outReadEvent(readBuffer)

Called when a read operation completes.

May be overridden in subclass.

outWriteEvent()

Called when a write operation completes.

May be overridden in subclass.

readable()

recv(bufferSize=16384)

send(writeBuffer)

writable()