mitmproxy/libmproxy/proxy.py

import sys, os, string, socket, time
import shutil, tempfile, threading
import SocketServer
from OpenSSL import SSL
from netlib import odict, tcp, http, certutils, http_status, http_auth
import utils, flow, version, platform, controller, protocol


TRANSPARENT_SSL_PORTS = [443, 8443]

KILL = 0


class ProxyError(Exception):
    def __init__(self, code, msg, headers=None):
        self.code, self.msg, self.headers = code, msg, headers

    def __str__(self):
        return "ProxyError(%s, %s)"%(self.code, self.msg)


class ProxyConfig:
    def __init__(self, certfile = None, cacert = None, clientcerts = None, no_upstream_cert=False, body_size_limit = None, reverse_proxy=None, forward_proxy=None, transparent_proxy=None, authenticator=None):
        self.certfile = certfile
        self.cacert = cacert
        self.clientcerts = clientcerts
        self.no_upstream_cert = no_upstream_cert
        self.body_size_limit = body_size_limit
        self.reverse_proxy = reverse_proxy
        self.forward_proxy = forward_proxy
        self.transparent_proxy = transparent_proxy
        self.authenticator = authenticator
        self.certstore = certutils.CertStore()


class ServerConnection(tcp.TCPClient):
    def __init__(self, config, host, port, sni):
        tcp.TCPClient.__init__(self, host, port)
        self.config = config
        self.sni = sni
        self.tcp_setup_timestamp = None
        self.ssl_setup_timestamp = None

    def connect(self):
        tcp.TCPClient.connect(self)
        self.tcp_setup_timestamp = time.time()

    def establish_ssl(self):
        clientcert = None
        if self.config.clientcerts:
            path = os.path.join(self.config.clientcerts, self.host.encode("idna")) + ".pem"
            if os.path.exists(path):
                clientcert = path
        try:
            self.convert_to_ssl(cert=clientcert, sni=self.sni)
            self.ssl_setup_timestamp = time.time()
        except tcp.NetLibError, v:
            raise ProxyError(400, str(v))

    def send(self, request):
        print "deprecated"
        d = request._assemble()
        if not d:
            raise ProxyError(502, "Cannot transmit an incomplete request.")
        self.wfile.write(d)
        self.wfile.flush()

    def terminate(self):
        if self.connection:
            try:
                self.wfile.flush()
            except tcp.NetLibDisconnect: # pragma: no cover
                pass
            self.connection.close()



class RequestReplayThread(threading.Thread):
    def __init__(self, config, flow, masterq):
        self.config, self.flow, self.channel = config, flow, controller.Channel(masterq)
        threading.Thread.__init__(self)

    def run(self):
        try:
            r = self.flow.request
            server = ServerConnection(self.config, r.scheme, r.host, r.port, r.host)
            server.connect()
            server.send(r)
            tsstart = utils.timestamp()
            httpversion, code, msg, headers, content = http.read_response(
                server.rfile, r.method, self.config.body_size_limit
            )
            response = flow.Response(
                self.flow.request, httpversion, code, msg, headers, content, server.cert, 
                server.rfile.first_byte_timestamp
            )
            self.channel.ask("response", response)
        except (ProxyError, http.HttpError, tcp.NetLibError), v:
            err = flow.Error(self.flow.request, str(v))
            self.channel.ask("error", err)

class ConnectionHandler:
    def __init__(self, config, client_connection, client_address, server, channel, server_version):
        self.config = config
        self.client_address, self.client_conn = client_address, tcp.BaseHandler(client_connection)
        self.server_address, self.server_conn = None, None
        self.channel, self.server_version = channel, server_version

        self.conntype = None
        self.sni = None

        self.mode = "regular"
        if self.config.reverse_proxy:
            self.mode = "reverse"
        if self.config.transparent_proxy:
            self.mode = "transparent"

    def del_server_connection(self):
        if self.server_conn:
            self.server_conn.terminate()
            self.channel.tell("serverdisconnect", self)
        self.server_conn = None
        self.sni = None

    def handle(self):
        self.log("connect")
        self.channel.ask("clientconnect", self)

        # Can we already identify the target server and connect to it?
        if self.config.forward_proxy:
            self.server_address = self.config.forward_proxy[1:]
        else:
            if self.config.reverse_proxy:
                self.server_address = self.config.reverse_proxy[1:]
            elif self.config.transparent_proxy:
                self.server_address = self.config.transparent_proxy["resolver"].original_addr(self.connection)
                if not self.server_address:
                    raise ProxyError(502, "Transparent mode failure: could not resolve original destination.")
                self.log("transparent to %s:%s"%self.server_address)

        if self.server_address:
            self.establish_server_connection()
            self.handle_ssl()

        self.determine_conntype(self.mode, *self.server_address)

        while not self.close:
            try:
                protocol.handle_messages(self.conntype, self)
            except protocol.ConnectionTypeChange:
                continue

        self.del_server_connection()

        self.log("disconnect")
        self.channel.tell("clientdisconnect", self)

    def determine_conntype(self, mode, host, port):
        #TODO: Add ruleset to select correct protocol depending on mode/target port etc.
        self.conntype = "http"

    def establish_server_connection(self):
        """
        Establishes a new server connection to self.server_address.
        If there is already an existing server connection, it will be killed.
        """
        self.del_server_connection()
        self.server_conn = ServerConnection(self.config, *self.server_address, self.sni)
        self.channel.tell("serverconnect", self)

    def handle_ssl(self):
        if self.config.transparent_proxy:
            client_ssl, server_ssl = (self.server_address[1] in self.config.transparent_proxy["sslports"])
        elif self.config.reverse_proxy:
            client_ssl, server_ssl = (self.config.reverse_proxy[0] == "https")
            # TODO: Make protocol generic (as with transparent proxies)
            # TODO: Add SSL-terminating capatbility (SSL -> mitmproxy -> plain and vice versa)
        else:
            client_ssl, server_ssl = True  # In regular mode, this function will only be called on HTTP CONNECT

        # TODO: Implement SSL pass-through handling and change conntype

        if server_ssl and not self.server_conn.ssl_established:
            self.server_conn.establish_ssl()
        if client_ssl and not self.client_conn.ssl_established:
            dummycert = self.find_cert()
            self.client_conn.convert_to_ssl(dummycert, self.config.certfile or self.config.cacert, handle_sni=self.handle_sni)

    def log(self, msg, subs=()):
        msg = [
            "%s:%s: "%(self.client_address, msg)
        ]
        for i in subs:
            msg.append("  -> "+i)
        msg = "\n".join(msg)
        self.channel.tell("log", msg)

    def find_cert(self):
        if self.config.certfile:
            with open(self.config.certfile, "rb") as f:
                return certutils.SSLCert.from_pem(f.read())
        else:
            host = self.server_address[0]
            sans = []
            if not self.config.no_upstream_cert or not self.server_conn.ssl_established:
                upstream_cert = self.server_conn.cert
                if upstream_cert.cn:
                    host = upstream_cert.cn.decode("utf8").encode("idna")
                sans = upstream_cert.altnames

            ret = self.config.certstore.get_cert(host, sans, self.config.cacert)
            if not ret:
                raise ProxyError(502, "Unable to generate dummy cert.")
            return ret

    def handle_sni(self, connection):
        """
        This callback gets called during the SSL handshake with the client.
        The client has just sent the Sever Name Indication (SNI). We now connect upstream to
        figure out which certificate needs to be served.
        """
        try:
            sn = connection.get_servername()
            if sn and sn != self.sni:
                self.sni = sn.decode("utf8").encode("idna")
                self.establish_server_connection()  # reconnect to upstream server with SNI
                self.handle_ssl() # establish SSL with upstream
                # Now, change client context to reflect changed certificate:
                new_context = SSL.Context(SSL.TLSv1_METHOD)
                new_context.use_privatekey_file(self.config.certfile or self.config.cacert)
                dummycert = self.find_cert()
                new_context.use_certificate(dummycert.x509)
                connection.set_context(new_context)
        # An unhandled exception in this method will core dump PyOpenSSL, so
        # make dang sure it doesn't happen.
        except Exception, e: # pragma: no cover
            pass

class ProxyServerError(Exception): pass


class ProxyServer(tcp.TCPServer):
    allow_reuse_address = True
    bound = True
    def __init__(self, config, port, address='', server_version=version.NAMEVERSION):
        """
            Raises ProxyServerError if there's a startup problem.
        """
        self.config, self.port, self.address = config, port, address
        self.server_version = server_version
        try:
            tcp.TCPServer.__init__(self, (address, port))
        except socket.error, v:
            raise ProxyServerError('Error starting proxy server: ' + v.strerror)
        self.channel = None

    def start_slave(self, klass, channel):
        slave = klass(channel, self)
        slave.start()

    def set_channel(self, channel):
        self.channel = channel

    def handle_client_connection(self, conn, client_address):
        h = ConnectionHandler(self.config, conn, client_address, self, self.channel, self.server_version)
        h.handle()
        h.finish()


class DummyServer:
    bound = False
    def __init__(self, config):
        self.config = config

    def start_slave(self, *args):
        pass

    def shutdown(self):
        pass


# Command-line utils
def certificate_option_group(parser):
    group = parser.add_argument_group("SSL")
    group.add_argument(
        "--cert", action="store",
        type = str, dest="cert", default=None,
        help = "User-created SSL certificate file."
    )
    group.add_argument(
        "--client-certs", action="store",
        type = str, dest = "clientcerts", default=None,
        help = "Client certificate directory."
    )



def process_proxy_options(parser, options):
    if options.cert:
        options.cert = os.path.expanduser(options.cert)
        if not os.path.exists(options.cert):
            return parser.error("Manually created certificate does not exist: %s"%options.cert)

    cacert = os.path.join(options.confdir, "mitmproxy-ca.pem")
    cacert = os.path.expanduser(cacert)
    if not os.path.exists(cacert):
        certutils.dummy_ca(cacert)
    body_size_limit = utils.parse_size(options.body_size_limit)
    if options.reverse_proxy and options.transparent_proxy:
        return parser.error("Can't set both reverse proxy and transparent proxy.")

    if options.transparent_proxy:
        if not platform.resolver:
            return parser.error("Transparent mode not supported on this platform.")
        trans = dict(
            resolver = platform.resolver(),
            sslports = TRANSPARENT_SSL_PORTS
        )
    else:
        trans = None

    if options.reverse_proxy:
        rp = utils.parse_proxy_spec(options.reverse_proxy)
        if not rp:
            return parser.error("Invalid reverse proxy specification: %s"%options.reverse_proxy)
    else:
        rp = None

    if options.forward_proxy:
        fp = utils.parse_proxy_spec(options.forward_proxy)
        if not fp:
            return parser.error("Invalid forward proxy specification: %s"%options.forward_proxy)
    else:
        fp = None

    if options.clientcerts:
        options.clientcerts = os.path.expanduser(options.clientcerts)
        if not os.path.exists(options.clientcerts) or not os.path.isdir(options.clientcerts):
            return parser.error(
                    "Client certificate directory does not exist or is not a directory: %s"%options.clientcerts
                )

    if (options.auth_nonanonymous or options.auth_singleuser or options.auth_htpasswd):
        if options.auth_singleuser:
            if len(options.auth_singleuser.split(':')) != 2:
                return parser.error("Invalid single-user specification. Please use the format username:password")
            username, password = options.auth_singleuser.split(':')
            password_manager = http_auth.PassManSingleUser(username, password)
        elif options.auth_nonanonymous:
            password_manager = http_auth.PassManNonAnon()
        elif options.auth_htpasswd:
            try:
                password_manager = http_auth.PassManHtpasswd(options.auth_htpasswd)
            except ValueError, v:
                return parser.error(v.message)
        authenticator = http_auth.BasicProxyAuth(password_manager, "mitmproxy")
    else:
        authenticator = http_auth.NullProxyAuth(None)

    return ProxyConfig(
        certfile = options.cert,
        cacert = cacert,
        clientcerts = options.clientcerts,
        body_size_limit = body_size_limit,
        no_upstream_cert = options.no_upstream_cert,
        reverse_proxy = rp,
        forward_proxy = fp,
        transparent_proxy = trans,
        authenticator = authenticator
    )