# -*- test-case-name: twisted.test.test_ssl -*-
# Copyright (c) 2001-2004 Twisted Matrix Laboratories.
# See LICENSE for details.


"""SSL transport. Requires PyOpenSSL (http://pyopenssl.sf.net).

SSL connections require a ContextFactory so they can create SSL contexts.
End users should only use the ContextFactory classes directly - for SSL
connections use the reactor.connectSSL/listenSSL and so on, as documented
in IReactorSSL.

All server context factories should inherit from ContextFactory, and all
client context factories should inherit from ClientContextFactory. At the
moment this is not enforced, but in the future it might be.

API Stability: stable

Future Plans:
    - split module so reactor-specific classes are in a separate module
    - support for switching TCP into SSL
    - more options

Maintainer: U{Itamar Shtull-Trauring<mailto:twisted@itamarst.org>}
"""

# If something goes wrong, most notably an OpenSSL import failure,
# sys.modules['twisted.internet.ssl'] will be bound to a partially
# initialized module object.  This is wacko, but we will take advantage
# of it to publish whether or not SSL is available.
# See the end of this module for the other half of this solution.

# The correct idiom to import this module is thus:

# try:
#    from twisted.internet import ssl
# except ImportError:
#    # happens the first time the interpreter tries to import it
#    ssl = None
# if ssl and not ssl.supported:
#    # happens second and later times
#    ssl = None

supported = False

# System imports
from OpenSSL import SSL
import socket
from zope.interface import implements, implementsOnly, implementedBy

# sibling imports
import tcp, interfaces

# Twisted imports
from twisted.python import log, components
from twisted.internet import base, address


class ContextFactory:
    """A factory for SSL context objects, for server SSL connections."""

    isClient = 0

    def getContext(self):
        """Return a SSL.Context object. override in subclasses."""
        raise NotImplementedError


class DefaultOpenSSLContextFactory(ContextFactory):

    def __init__(self, privateKeyFileName, certificateFileName,
                 sslmethod=SSL.SSLv23_METHOD):
        """
        @param privateKeyFileName: Name of a file containing a private key
        @param certificateFileName: Name of a file containing a certificate
        @param sslmethod: The SSL method to use
        """
        self.privateKeyFileName = privateKeyFileName
        self.certificateFileName = certificateFileName
        self.sslmethod = sslmethod
        self.cacheContext()

    def cacheContext(self):
        ctx = SSL.Context(self.sslmethod)
        ctx.use_certificate_file(self.certificateFileName)
        ctx.use_privatekey_file(self.privateKeyFileName)
        self._context = ctx

    def __getstate__(self):
        d = self.__dict__.copy()
        del d['_context']
        return d

    def __setstate__(self, state):
        self.__dict__ = state
        self.cacheContext()

    def getContext(self):
        """Create an SSL context.
        """
        return self._context


class ClientContextFactory:
    """A context factory for SSL clients."""

    isClient = 1
    method = SSL.SSLv3_METHOD

    def getContext(self):
        return SSL.Context(self.method)


class Client(tcp.Client):
    """I am an SSL client."""

    implementsOnly(interfaces.ISSLTransport,
                   *[i for i in implementedBy(tcp.Client) if i != interfaces.ITLSTransport])
    
    def __init__(self, host, port, bindAddress, ctxFactory, connector, reactor=None):
        # tcp.Client.__init__ depends on self.ctxFactory being set
        self.ctxFactory = ctxFactory
        tcp.Client.__init__(self, host, port, bindAddress, connector, reactor)

    def getHost(self):
        """Returns the address from which I am connecting."""
        h, p = self.socket.getsockname()
        return address.IPv4Address('TCP', h, p, 'SSL')

    def getPeer(self):
        """Returns the address that I am connected."""
        return address.IPv4Address('TCP', self.addr[0], self.addr[1], 'SSL')

    def _connectDone(self):
        self.startTLS(self.ctxFactory)
        self.startWriting()
        tcp.Client._connectDone(self)

components.backwardsCompatImplements(Client)


class Server(tcp.Server):
    """I am an SSL server.
    """

    implements(interfaces.ISSLTransport)
    
    def getHost(self):
        """Return server's address."""
        h, p = self.socket.getsockname()
        return address.IPv4Address('TCP', h, p, 'SSL')

    def getPeer(self):
        """Return address of peer."""
        h, p = self.client
        return address.IPv4Address('TCP', h, p, 'SSL')

components.backwardsCompatImplements(Server)


class Port(tcp.Port):
    """I am an SSL port."""
    _socketShutdownMethod = 'sock_shutdown'
    
    transport = Server

    def __init__(self, port, factory, ctxFactory, backlog=5, interface='', reactor=None):
        tcp.Port.__init__(self, port, factory, backlog, interface, reactor)
        self.ctxFactory = ctxFactory

    def createInternetSocket(self):
        """(internal) create an SSL socket
        """
        sock = tcp.Port.createInternetSocket(self)
        return SSL.Connection(self.ctxFactory.getContext(), sock)

    def _preMakeConnection(self, transport):
        # *Don't* call startTLS here
        # The transport already has the SSL.Connection object from above
        transport._startTLS()
        return tcp.Port._preMakeConnection(self, transport)


class Connector(base.BaseConnector):
    def __init__(self, host, port, factory, contextFactory, timeout, bindAddress, reactor=None):
        self.host = host
        self.port = port
        self.bindAddress = bindAddress
        self.contextFactory = contextFactory
        base.BaseConnector.__init__(self, factory, timeout, reactor)

    def _makeTransport(self):
        return Client(self.host, self.port, self.bindAddress, self.contextFactory, self, self.reactor)

    def getDestination(self):
        return address.IPv4Address('TCP', self.host, self.port, 'SSL')
 

__all__ = ["ContextFactory", "DefaultOpenSSLContextFactory", "ClientContextFactory"]

supported = True
