Wrapping an existing socket in SSL - Python

问题

I'm having some trouble wrapping an existing socket connection in ssl in a Python program. Essentially, it's an implementation of STARTTLS, i.e. a currently connected client can issue the STARTTLS command and the server will secure the connection.

Here's the portion of the code that I'm struggling with:

self.client_s = ssl.wrap_socket(
    self.client_s,
    certfile='/path/to/cert.crt',
    keyfile='/path/to/key.key',
    do_handshake_on_connect=False
    )
while True:
    try:
        self.client_s.do_handshake()
        break
    except ssl.SSLError, e:
        if e.args[0] == ssl.SSL_ERROR_WANT_READ:
            select([self.client_s], [], [])
        elif e.args[0] == ssl.SSL_ERROR_WANT_WRITE:
            select([], [self.client_s], [])
        else: raise

When I connect using openssl, I get the following:

_ssl.c:491: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

I'm connecting by running this:

openssl s_client -connect localhost:50000 -crlf -starttls smtp -debug -ssl3

Changing the openssl command to use -ssl2, -no_ssl2, or -tls1 is no help. I've also tried adding server_side=True to wrap_socket() but just causes the ssl handshake to time-out.

I should note that wrap_socket() works fine when the connection is encrypted from start to finish, just not when I try to use it in a STARTTLS context.

Python version is 2.4.3

Thanks in advance, I appreciate any pointers or help.

来源：https://stackoverflow.com/questions/11994949/wrapping-an-existing-socket-in-ssl-python