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HTTPS proxy tunneling with the ssl module

I'd like to manually (using the socket and ssl modules) make an HTTPS request through a proxy which itself uses HTTPS.

I can perform the initial CONNECT exchange just fine:

import ssl, socket

PROXY_ADDR = ("proxy-addr", 443)
CONNECT = "CONNECT example.com:443 HTTP/1.1\r\n\r\n"

sock = socket.create_connection(PROXY_ADDR)
sock = ssl.wrap_socket(sock)
sock.sendall(CONNECT)
s = ""
while s[-4:] != "\r\n\r\n":
    s += sock.recv(1)
print repr(s)

The above code prints HTTP/1.1 200 Connection established plus some headers, which is what I expect. So now I should be ready to make the request, e.g.

sock.sendall("GET / HTTP/1.1\r\n\r\n")

but the above code returns

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>400 Bad Request</title>
</head><body>
<h1>Bad Request</h1>
<p>Your browser sent a request that this server could not understand.<br />
Reason: You're speaking plain HTTP to an SSL-enabled server port.<br />
Instead use the HTTPS scheme to access this URL, please.<br />
</body></html>

This makes sense too, since I still need to do an SSL handshake with the example.com server to which I'm tunneling. However, if instead of immediately sending the GET request I say

sock = ssl.wrap_socket(sock)

to do the handshake with the remote server, then I get an exception:

Traceback (most recent call last):
  File "so_test.py", line 18, in <module>
    ssl.wrap_socket(sock)
  File "/usr/lib/python2.6/ssl.py", line 350, in wrap_socket
    suppress_ragged_eofs=suppress_ragged_eofs)
  File "/usr/lib/python2.6/ssl.py", line 118, in __init__
    self.do_handshake()
  File "/usr/lib/python2.6/ssl.py", line 293, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [Errno 1] _ssl.c:480: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

So how can I do the SSL handshake with the remote example.com server?

EDIT: I'm pretty sure that no additional data is available before my second call to wrap_socket because calling sock.recv(1) blocks indefinitely.

like image 858
Eli Courtwright Avatar asked Dec 08 '10 22:12

Eli Courtwright


1 Answers

Finally I got somewhere expanding on @kravietz and @02strich answers.

Here's the code

import threading
import select
import socket
import ssl

server = 'mail.google.com'
port = 443
PROXY = ("localhost", 4433)
CONNECT = "CONNECT %s:%s HTTP/1.0\r\nConnection: close\r\n\r\n" % (server, port)


class ForwardedSocket(threading.Thread):
    def __init__(self, s, **kwargs):
        threading.Thread.__init__(self)
        self.dest = s
        self.oursraw, self.theirsraw = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
        self.theirs = socket.socket(_sock=self.theirsraw)
        self.start()
        self.ours = ssl.wrap_socket(socket.socket(_sock=self.oursraw), **kwargs)

    def run(self):
        rl, wl, xl = select.select([self.dest, self.theirs], [], [], 1)
        print rl, wl, xl
        # FIXME write may block
        if self.theirs in rl:
            self.dest.send(self.theirs.recv(4096))
        if self.dest in rl:
            self.theirs.send(self.dest.recv(4096))

    def recv(self, *args):
        return self.ours.recv(*args)

    def send(self, *args):
        return self.outs.recv(*args)


def test():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect(PROXY)
    s = ssl.wrap_socket(s, ciphers="ALL:aNULL:eNULL")
    s.send(CONNECT)
    resp = s.read(4096)
    print (resp, )

    fs = ForwardedSocket(s, ciphers="ALL:aNULL:eNULL")
    fs.send("foobar")

Don't mind custom cihpers=, that only because I didn't want to deal with certificates.

And there's depth-1 ssl output, showing CONNECT, my response to it ssagd and depth-2 ssl negotiation and binary rubbish:

[dima@bmg ~]$ openssl s_server  -nocert -cipher "ALL:aNULL:eNULL"
Using default temp DH parameters
Using default temp ECDH parameters
ACCEPT
-----BEGIN SSL SESSION PARAMETERS-----
MHUCAQECAgMDBALAGQQgmn6XfJt8ru+edj6BXljltJf43Sz6AmacYM/dSmrhgl4E
MOztEauhPoixCwS84DL29MD/OxuxuvG5tnkN59ikoqtfrnCKsk8Y9JtUU9zuaDFV
ZaEGAgRSnJ81ogQCAgEspAYEBAEAAAA=
-----END SSL SESSION PARAMETERS-----
Shared ciphers: [snipped]
CIPHER is AECDH-AES256-SHA
Secure Renegotiation IS supported
CONNECT mail.google.com:443 HTTP/1.0
Connection: close

sagq
�u\�0�,�(�$��
�"�!��kj98���� �m:��2�.�*�&���=5�����
��/�+�'�#��     ����g@32��ED���l4�F�1�-�)�%���</�A������
                                                        ��      ������
                                                                      �;��A��q�J&O��y�l
like image 129
Dima Tisnek Avatar answered Sep 20 '22 21:09

Dima Tisnek