# Copyright (C) 2012  Aldo Cortesi
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
import sys, os, string, socket, time
import shutil, tempfile, threading
import optparse, SocketServer
from OpenSSL import SSL
from netlib import odict, tcp, http, wsgi, certutils
import utils, flow, version, platform


class ProxyError(Exception):
    def __init__(self, code, msg):
        self.code, self.msg = code, msg

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


class ProxyConfig:
    def __init__(self, certfile = None, cacert = None, clientcerts = None, cert_wait_time=0, upstream_cert=False, body_size_limit = None, reverse_proxy=None, transparent_proxy=None):
        assert not (reverse_proxy and transparent_proxy)
        self.certfile = certfile
        self.cacert = cacert
        self.clientcerts = clientcerts
        self.certdir = None
        self.cert_wait_time = cert_wait_time
        self.upstream_cert = upstream_cert
        self.body_size_limit = body_size_limit
        self.reverse_proxy = reverse_proxy
        self.transparent_proxy = transparent_proxy


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

    def run(self):
        try:
            r = self.flow.request
            server = ServerConnection(self.config, r.host, r.port)
            server.connect(r.scheme)
            server.send(r)
            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
            )
            response._send(self.masterq)
        except (ProxyError, http.HttpError), v:
            err = flow.Error(self.flow.request, v.msg)
            err._send(self.masterq)
        except tcp.NetLibError, v:
            raise ProxyError(502, v)


class ServerConnection(tcp.TCPClient):
    def __init__(self, config, host, port):
        tcp.TCPClient.__init__(self, host, port)
        self.config = config
        self.requestcount = 0

    def connect(self, scheme):
        tcp.TCPClient.connect(self)
        if scheme == "https":
            clientcert = None
            if self.config.clientcerts:
                path = os.path.join(self.config.clientcerts, self.host) + ".pem"
                if os.path.exists(clientcert):
                    clientcert = path
            self.convert_to_ssl(clientcert=clientcert)

    def send(self, request):
        self.requestcount += 1
        try:
            d = request._assemble()
            if not d:
                raise ProxyError(502, "Incomplete request could not not be readied for transmission.")
            self.wfile.write(d)
            self.wfile.flush()
        except socket.error, err:
            raise ProxyError(502, 'Error sending data to "%s": %s' % (request.host, err))

    def terminate(self):
        try:
            if not self.wfile.closed:
                self.wfile.flush()
            self.connection.close()
        except IOError:
            pass


class ProxyHandler(tcp.BaseHandler):
    def __init__(self, config, connection, client_address, server, q):
        self.mqueue = q
        self.config = config
        self.server_conn = None
        self.proxy_connect_state = None
        self.sni = None
        tcp.BaseHandler.__init__(self, connection, client_address, server)

    def handle(self):
        cc = flow.ClientConnect(self.client_address)
        cc._send(self.mqueue)
        while self.handle_request(cc) and not cc.close:
            pass
        cc.close = True
        cd = flow.ClientDisconnect(cc)
        cd._send(self.mqueue)

    def server_connect(self, scheme, host, port):
        sc = self.server_conn
        if sc and (host, port) != (sc.host, sc.port):
            sc.terminate()
            self.server_conn = None
        if not self.server_conn:
            try:
                self.server_conn = ServerConnection(self.config, host, port)
                self.server_conn.connect(scheme)
            except tcp.NetLibError, v:
                raise ProxyError(502, v)

    def handle_request(self, cc):
        try:
            request, err = None, None
            request = self.read_request(cc)
            if request is None:
                return
            cc.requestcount += 1

            app = self.server.apps.get(request)
            if app:
                app.serve(request, self.wfile)
            else:
                request = request._send(self.mqueue)
                if request is None:
                    return

                if isinstance(request, flow.Response):
                    response = request
                    request = False
                    response = response._send(self.mqueue)
                else:
                    if self.config.reverse_proxy:
                        scheme, host, port = self.config.reverse_proxy
                    else:
                        scheme, host, port = request.scheme, request.host, request.port
                    self.server_connect(scheme, host, port)
                    self.server_conn.send(request)
                    httpversion, code, msg, headers, content = http.read_response(
                        self.server_conn.rfile,
                        request.method,
                        self.config.body_size_limit
                    )
                    response = flow.Response(
                        request, httpversion, code, msg, headers, content, self.server_conn.cert
                    )
                    response = response._send(self.mqueue)
                    if response is None:
                        self.server_conn.terminate()
                if response is None:
                    return
                self.send_response(response)
                if http.request_connection_close(request.httpversion, request.headers):
                    return
                # We could keep the client connection when the server
                # connection needs to go away.  However, we want to mimic
                # behaviour as closely as possible to the client, so we
                # disconnect.
                if http.response_connection_close(response.httpversion, response.headers):
                    return
        except IOError, v:
            cc.connection_error = v
        except (ProxyError, http.HttpError), e:
            cc.connection_error = "%s: %s"%(e.code, e.msg)
            if request:
                err = flow.Error(request, e.msg)
                err._send(self.mqueue)
            self.send_error(e.code, e.msg)
        else:
            return True

    def find_cert(self, host, port, sni):
        if self.config.certfile:
            return self.config.certfile
        else:
            sans = []
            if self.config.upstream_cert:
                cert = certutils.get_remote_cert(host, port, sni)
                sans = cert.altnames
                host = cert.cn
            ret = certutils.dummy_cert(self.config.certdir, self.config.cacert, host, sans)
            time.sleep(self.config.cert_wait_time)
            if not ret:
                raise ProxyError(502, "mitmproxy: Unable to generate dummy cert.")
            return ret

    def get_line(self, fp):
        """
            Get a line, possibly preceded by a blank.
        """
        line = fp.readline()
        if line == "\r\n" or line == "\n": # Possible leftover from previous message
            line = fp.readline()
        return line

    def handle_sni(self, conn):
        self.sni = conn.get_servername()

    def read_request(self, client_conn):
        if self.config.transparent_proxy:
            host, port = self.config.transparent_proxy["resolver"].original_addr(self.connection)
            if not self.ssl_established and (port in self.config.transparent_proxy["sslports"]):
                scheme = "https"
                certfile = self.find_cert(host, port, None)
                self.convert_to_ssl(certfile, self.config.certfile or self.config.cacert)
            else:
                scheme = "http"
            host = self.sni or host
            line = self.get_line(self.rfile)
            if line == "":
                return None
            r = http.parse_init_http(line)
            if not r:
                raise ProxyError(400, "Bad HTTP request line: %s"%line)
            method, path, httpversion = r
            headers = http.read_headers(self.rfile)
            content = http.read_http_body_request(
                        self.rfile, self.wfile, headers, httpversion, self.config.body_size_limit
                    )
            return flow.Request(client_conn, httpversion, host, port, scheme, method, path, headers, content)
        elif self.config.reverse_proxy:
            line = self.get_line(self.rfile)
            if line == "":
                return None
            scheme, host, port = self.config.reverse_proxy
            r = http.parse_init_http(line)
            if not r:
                raise ProxyError(400, "Bad HTTP request line: %s"%line)
            method, path, httpversion = r
            headers = http.read_headers(self.rfile)
            content = http.read_http_body_request(
                        self.rfile, self.wfile, headers, httpversion, self.config.body_size_limit
                    )
            return flow.Request(client_conn, httpversion, host, port, "http", method, path, headers, content)
        else:
            line = self.get_line(self.rfile)
            if line == "":
                return None
            if line.startswith("CONNECT"):
                r = http.parse_init_connect(line)
                if not r:
                    raise ProxyError(400, "Bad HTTP request line: %s"%line)
                host, port, httpversion = r
                # FIXME: Discard additional headers sent to the proxy. Should I expose
                # these to users?
                while 1:
                    d = self.rfile.readline()
                    if d == '\r\n' or d == '\n':
                        break
                self.wfile.write(
                            'HTTP/1.1 200 Connection established\r\n' +
                            ('Proxy-agent: %s\r\n'%version.NAMEVERSION) +
                            '\r\n'
                            )
                self.wfile.flush()
                certfile = self.find_cert(host, port, None)
                self.convert_to_ssl(certfile, self.config.certfile or self.config.cacert)
                self.proxy_connect_state = (host, port, httpversion)
                line = self.rfile.readline(line)
            if self.proxy_connect_state:
                host, port, httpversion = self.proxy_connect_state
                r = http.parse_init_http(line)
                if not r:
                    raise ProxyError(400, "Bad HTTP request line: %s"%line)
                method, path, httpversion = r
                headers = http.read_headers(self.rfile)
                content = http.read_http_body_request(
                    self.rfile, self.wfile, headers, httpversion, self.config.body_size_limit
                )
                return flow.Request(client_conn, httpversion, host, port, "https", method, path, headers, content)
            else:
                r = http.parse_init_proxy(line)
                if not r:
                    raise ProxyError(400, "Bad HTTP request line: %s"%line)
                method, scheme, host, port, path, httpversion = http.parse_init_proxy(line)
                headers = http.read_headers(self.rfile)
                content = http.read_http_body_request(
                    self.rfile, self.wfile, headers, httpversion, self.config.body_size_limit
                )
                return flow.Request(client_conn, httpversion, host, port, scheme, method, path, headers, content)

    def send_response(self, response):
        d = response._assemble()
        if not d:
            raise ProxyError(502, "Incomplete response could not not be readied for transmission.")
        self.wfile.write(d)
        self.wfile.flush()

    def send_error(self, code, body):
        try:
            import BaseHTTPServer
            response = BaseHTTPServer.BaseHTTPRequestHandler.responses[code][0]
            self.wfile.write("HTTP/1.1 %s %s\r\n" % (code, response))
            self.wfile.write("Server: %s\r\n"%version.NAMEVERSION)
            self.wfile.write("Connection: close\r\n")
            self.wfile.write("Content-type: text/html\r\n")
            self.wfile.write("\r\n")
            self.wfile.write('<html><head>\n<title>%d %s</title>\n</head>\n'
                    '<body>\n%s\n</body>\n</html>' % (code, response, body))
            self.wfile.flush()
        except:
            pass


class ProxyServerError(Exception): pass


class ProxyServer(tcp.TCPServer):
    allow_reuse_address = True
    bound = True
    def __init__(self, config, port, address=''):
        """
            Raises ProxyServerError if there's a startup problem.
        """
        self.config, self.port, self.address = config, port, address
        try:
            tcp.TCPServer.__init__(self, (address, port))
        except socket.error, v:
            raise ProxyServerError('Error starting proxy server: ' + v.strerror)
        self.masterq = None
        self.certdir = tempfile.mkdtemp(prefix="mitmproxy")
        config.certdir = self.certdir
        self.apps = AppRegistry()

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

    def set_mqueue(self, q):
        self.masterq = q

    def handle_connection(self, request, client_address):
        h = ProxyHandler(self.config, request, client_address, self, self.masterq)
        h.handle()
        h.finish()

    def handle_shutdown(self):
        try:
            shutil.rmtree(self.certdir)
        except OSError:
            pass


class AppRegistry:
    def __init__(self):
        self.apps = {}

    def add(self, app, domain, port):
        """
            Add a WSGI app to the registry, to be served for requests to the
            specified domain, on the specified port.
        """
        self.apps[(domain, port)] = wsgi.WSGIAdaptor(app, domain, port, version.NAMEVERSION)

    def get(self, request):
        """
            Returns an WSGIAdaptor instance if request matches an app, or None.
        """
        return self.apps.get((request.host, request.port), None)


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

    def start_slave(self, klass, masterq):
        pass

    def shutdown(self):
        pass


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


TRANSPARENT_SSL_PORTS = [443, 8443]

def process_proxy_options(parser, options):
    if options.cert:
        options.cert = os.path.expanduser(options.cert)
        if not os.path.exists(options.cert):
            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)
    if getattr(options, "cache", None) is not None:
        options.cache = os.path.expanduser(options.cache)
    body_size_limit = utils.parse_size(options.body_size_limit)

    if options.reverse_proxy and options.transparent_proxy:
        parser.errror("Can't set both reverse proxy and transparent proxy.")

    if options.transparent_proxy:
        if not platform.resolver:
            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:
            parser.error("Invalid reverse proxy specification: %s"%options.reverse_proxy)
    else:
        rp = 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):
            parser.error("Client certificate directory does not exist or is not a directory: %s"%options.clientcerts)

    return ProxyConfig(
        certfile = options.cert,
        cacert = cacert,
        clientcerts = options.clientcerts,
        cert_wait_time = options.cert_wait_time,
        body_size_limit = body_size_limit,
        upstream_cert = options.upstream_cert,
        reverse_proxy = rp,
        transparent_proxy = trans
    )