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python/gdata/tlslite/integration/TLSAsyncDispatcherMixIn.py

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+"""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)