Transparent HTTP Tunnel for Python sockets (to be used by ftplib ) (Python recipe) by Raphaël Jolivet

ActiveState Code (http://code.activestate.com/recipes/577643/)

#!/usr/bin/python
import socket

# Class that wraps a real socket and changes it to a HTTP tunnel whenever a connection is asked via the "connect" method
class ProxySock :
    
    def __init__(self, socket, proxy_host, proxy_port) : 

        # First, use the socket, without any change
        self.socket = socket

        # Create socket (use real one)
        self.proxy_host = proxy_host
        self.proxy_port = proxy_port

        # Copy attributes
        self.family = socket.family
        self.type = socket.type
        self.proto = socket.proto

    def connect(self, address) :

        # Store the real remote adress
        (self.host, self.port) = address
       
        # Try to connect to the proxy 
        for (family, socktype, proto, canonname, sockaddr) in socket.getaddrinfo(
            self.proxy_host, 
            self.proxy_port,
            0, 0, socket.SOL_TCP) :
            try:
                
                # Replace the socket by a connection to the proxy
                self.socket = socket.socket_formal(family, socktype, proto)
                self.socket.connect(sockaddr)
                    
            except socket.error, msg:
                if self.socket:
                    self.socket.close()
                self.socket = None
                continue
            break
        if not self.socket :
            raise socket.error, ms 
        
        # Ask him to create a tunnel connection to the target host/port
        self.socket.send(
                ("CONNECT %s:%d HTTP/1.1\r\n" + 
                "Host: %s:%d\r\n\r\n") % (self.host, self.port, self.host, self.port));

        # Get the response
        resp = self.socket.recv(4096)

        # Parse the response
        parts = resp.split()
        
        # Not 200 ?
        if parts[1] != "200" :
            raise Exception("Error response from Proxy server : %s" % resp)

    # Wrap all methods of inner socket, without any change
    def accept(self) :
        return self.socket.accept()

    def bind(self, *args) :
        return self.socket.bind(*args)
    
    def close(self) :
        return self.socket.close()
    
    def fileno(self) :
        return self.socket.fileno()

    
    def getsockname(self) :
        return self.socket.getsockname()
    
    def getsockopt(self, *args) :
        return self.socket.getsockopt(*args)
    
    def listen(self, *args) :
        return self.socket.listen(*args)
    
    def makefile(self, *args) :
        return self.socket.makefile(*args)
    
    def recv(self, *args) :
        return self.socket.recv(*args)
    
    def recvfrom(self, *args) :
        return self.socket.recvfrom(*args)

    def recvfrom_into(self, *args) :
        return self.socket.recvfrom_into(*args)
    
    def recv_into(self, *args) :
        return self.socket.recv_into(buffer, *args)
    
    def send(self, *args) :
        return self.socket.send(*args)
    
    def sendall(self, *args) :
        return self.socket.sendall(*args)
    
    def sendto(self, *args) :
        return self.socket.sendto(*args)
    
    def setblocking(self, *args) :
        return self.socket.setblocking(*args)
    
    def settimeout(self, *args) :
        return self.socket.settimeout(*args)
    
    def gettimeout(self) :
        return self.socket.gettimeout()
    
    def setsockopt(self, *args):
        return self.socket.setsockopt(*args)
    
    def shutdown(self, *args):
        return self.socket.shutdown(*args)

    # Return the (host, port) of the actual target, not the proxy gateway
    def getpeername(self) :
        return (self.host, self.port)

# Install a proxy, by changing the method socket.socket()
def setup_http_proxy(proxy_host, proxy_port) :

    # New socket constructor that returns a ProxySock, wrapping a real socket
    def socket_proxy(af, socktype, proto) :

        # Create a socket, old school :
        sock = socket.socket_formal(af, socktype, proto)

        # Wrap it within a proxy socket
        return ProxySock(
                sock,
                proxy_host, 
                proxy_port)

    # Replace the "socket" method by our custom one
    socket.socket_formal = socket.socket
    socket.socket = socket_proxy