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"""TLS Lite + asyncore."""
import asyncore
from Bcfg2.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)
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