Using SSL With Eventlet
***********************

Eventlet makes it easy to use non-blocking SSL sockets.  If you're
using Python 2.6 or later, you're all set, eventlet wraps the built-in
ssl module.  If on Python 2.5 or 2.4, you have to install pyOpenSSL to
use eventlet.

In either case, the "green" modules handle SSL sockets transparently,
just like their standard counterparts.  As an example,
"eventlet.green.urllib2" can be used to fetch https urls in as non-
blocking a fashion as you please:

   from eventlet.green import urllib2
   from eventlet import spawn
   bodies = [spawn(urllib2.urlopen, url)
        for url in ("https://secondlife.com","https://google.com")]
   for b in bodies:
       print(b.wait().read())


With Python 2.6
===============

To use ssl sockets directly in Python 2.6, use "eventlet.green.ssl",
which is a non-blocking wrapper around the standard Python "ssl"
module, and which has the same interface.  See the standard
documentation for instructions on use.


With Python 2.5 or Earlier
==========================

Prior to Python 2.6, there is no "ssl", so SSL support is much weaker.
Eventlet relies on pyOpenSSL to implement its SSL support on these
older versions, so be sure to install pyOpenSSL, or you'll get an
ImportError whenever your system tries to make an SSL connection.

Once pyOpenSSL is installed, you can then use the "eventlet.green"
modules, like "eventlet.green.httplib" to fetch https urls.  You can
also use "eventlet.green.socket.ssl()", which is a nonblocking wrapper
for "socket.ssl()".


PyOpenSSL
=========

"eventlet.green.OpenSSL" has exactly the same interface as pyOpenSSL
(docs), and works in all versions of Python.  This module is much more
powerful than "socket.ssl()", and may have some advantages over "ssl",
depending on your needs.

Here's an example of a server:

   from eventlet.green import socket
   from eventlet.green.OpenSSL import SSL

   # insecure context, only for example purposes
   context = SSL.Context(SSL.SSLv23_METHOD)
   context.set_verify(SSL.VERIFY_NONE, lambda *x: True))

   # create underlying green socket and wrap it in ssl
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   connection = SSL.Connection(context, sock)

   # configure as server
   connection.set_accept_state()
   connection.bind(('127.0.0.1', 80443))
   connection.listen(50)

   # accept one client connection then close up shop
   client_conn, addr = connection.accept()
   print(client_conn.read(100))
   client_conn.shutdown()
   client_conn.close()
   connection.close()
