Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1001 insertions, 0 deletions

diff --git a/testing/tools/iceserver/iceserver.py b/testing/tools/iceserver/iceserver.py
new file mode 100644
index 0000000000..ae35bf0780
--- /dev/null
+++ b/testing/tools/iceserver/iceserver.py
@@ -0,0 +1,1001 @@
+# vim: set ts=4 et sw=4 tw=80
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import ipaddr
+import socket
+import hmac
+import hashlib
+import passlib.utils  # for saslprep
+import copy
+import random
+import operator
+import os
+import platform
+import six
+import string
+import time
+from functools import reduce
+from string import Template
+from twisted.internet import reactor, protocol
+from twisted.internet.task import LoopingCall
+from twisted.internet.address import IPv4Address
+from twisted.internet.address import IPv6Address
+
+MAGIC_COOKIE = 0x2112A442
+
+REQUEST = 0
+INDICATION = 1
+SUCCESS_RESPONSE = 2
+ERROR_RESPONSE = 3
+
+BINDING = 0x001
+ALLOCATE = 0x003
+REFRESH = 0x004
+SEND = 0x006
+DATA_MSG = 0x007
+CREATE_PERMISSION = 0x008
+CHANNEL_BIND = 0x009
+
+# STUN spec chose silly values for these
+STUN_IPV4 = 1
+STUN_IPV6 = 2
+
+MAPPED_ADDRESS = 0x0001
+USERNAME = 0x0006
+MESSAGE_INTEGRITY = 0x0008
+ERROR_CODE = 0x0009
+UNKNOWN_ATTRIBUTES = 0x000A
+LIFETIME = 0x000D
+DATA_ATTR = 0x0013
+XOR_PEER_ADDRESS = 0x0012
+REALM = 0x0014
+NONCE = 0x0015
+XOR_RELAYED_ADDRESS = 0x0016
+REQUESTED_TRANSPORT = 0x0019
+DONT_FRAGMENT = 0x001A
+XOR_MAPPED_ADDRESS = 0x0020
+SOFTWARE = 0x8022
+ALTERNATE_SERVER = 0x8023
+FINGERPRINT = 0x8028
+
+STUN_PORT = 3478
+STUNS_PORT = 5349
+
+TURN_REDIRECT_PORT = 3479
+TURNS_REDIRECT_PORT = 5350
+
+
+def unpack_uint(bytes_buf):
+    result = 0
+    for byte in bytes_buf:
+        result = (result << 8) + byte
+    return result
+
+
+def pack_uint(value, width):
+    if value < 0:
+        raise ValueError("Invalid value: {}".format(value))
+    buf = bytearray([0] * width)
+    for i in range(0, width):
+        buf[i] = (value >> (8 * (width - i - 1))) & 0xFF
+
+    return buf
+
+
+def unpack(bytes_buf, format_array):
+    results = ()
+    for width in format_array:
+        results = results + (unpack_uint(bytes_buf[0:width]),)
+        bytes_buf = bytes_buf[width:]
+    return results
+
+
+def pack(values, format_array):
+    if len(values) != len(format_array):
+        raise ValueError()
+    buf = bytearray()
+    for i in range(0, len(values)):
+        buf.extend(pack_uint(values[i], format_array[i]))
+    return buf
+
+
+def bitwise_pack(source, dest, start_bit, num_bits):
+    if num_bits <= 0 or num_bits > start_bit + 1:
+        raise ValueError(
+            "Invalid num_bits: {}, start_bit = {}".format(num_bits, start_bit)
+        )
+    last_bit = start_bit - num_bits + 1
+    source = source >> last_bit
+    dest = dest << num_bits
+    mask = (1 << num_bits) - 1
+    dest += source & mask
+    return dest
+
+
+def to_ipaddress(protocol, host, port):
+    if ":" not in host:
+        return IPv4Address(protocol, host, port)
+
+    return IPv6Address(protocol, host, port)
+
+
+class StunAttribute(object):
+    """
+    Represents a STUN attribute in a raw format, according to the following:
+
+     0                   1                   2                   3
+     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |   StunAttribute.attr_type     |  Length (derived as needed)   |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |           StunAttribute.data (variable length)             ....
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    """
+
+    __attr_header_fmt = [2, 2]
+    __attr_header_size = reduce(operator.add, __attr_header_fmt)
+
+    def __init__(self, attr_type=0, buf=bytearray()):
+        self.attr_type = attr_type
+        self.data = buf
+
+    def build(self):
+        buf = pack((self.attr_type, len(self.data)), self.__attr_header_fmt)
+        buf.extend(self.data)
+        # add padding if necessary
+        if len(buf) % 4:
+            buf.extend([0] * (4 - (len(buf) % 4)))
+        return buf
+
+    def parse(self, buf):
+        if self.__attr_header_size > len(buf):
+            raise Exception("truncated at attribute: incomplete header")
+
+        self.attr_type, length = unpack(buf, self.__attr_header_fmt)
+        length += self.__attr_header_size
+
+        if length > len(buf):
+            raise Exception("truncated at attribute: incomplete contents")
+
+        self.data = buf[self.__attr_header_size : length]
+
+        # verify padding
+        while length % 4:
+            if buf[length]:
+                raise ValueError("Non-zero padding")
+            length += 1
+
+        return length
+
+
+class StunMessage(object):
+    """
+    Represents a STUN message. Contains a method, msg_class, cookie,
+    transaction_id, and attributes (as an array of StunAttribute).
+
+    Has various functions for getting/adding attributes.
+    """
+
+    def __init__(self):
+        self.method = 0
+        self.msg_class = 0
+        self.cookie = MAGIC_COOKIE
+        self.transaction_id = 0
+        self.attributes = []
+
+    #      0                   1                   2                   3
+    #      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    #     |0 0|M M M M M|C|M M M|C|M M M M|         Message Length        |
+    #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    #     |                         Magic Cookie                          |
+    #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    #     |                                                               |
+    #     |                     Transaction ID (96 bits)                  |
+    #     |                                                               |
+    #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    __header_fmt = [2, 2, 4, 12]
+    __header_size = reduce(operator.add, __header_fmt)
+
+    # Returns how many bytes were parsed if buf was large enough, or how many
+    # bytes we would have needed if not. Throws if buf is malformed.
+    def parse(self, buf):
+        min_buf_size = self.__header_size
+        if len(buf) < min_buf_size:
+            return min_buf_size
+
+        message_type, length, cookie, self.transaction_id = unpack(
+            buf, self.__header_fmt
+        )
+        min_buf_size += length
+        if len(buf) < min_buf_size:
+            return min_buf_size
+
+        # Avert your eyes...
+        self.method = bitwise_pack(message_type, 0, 13, 5)
+        self.msg_class = bitwise_pack(message_type, 0, 8, 1)
+        self.method = bitwise_pack(message_type, self.method, 7, 3)
+        self.msg_class = bitwise_pack(message_type, self.msg_class, 4, 1)
+        self.method = bitwise_pack(message_type, self.method, 3, 4)
+
+        if cookie != self.cookie:
+            raise Exception("Invalid cookie: {}".format(cookie))
+
+        buf = buf[self.__header_size : min_buf_size]
+        while len(buf):
+            attr = StunAttribute()
+            length = attr.parse(buf)
+            buf = buf[length:]
+            self.attributes.append(attr)
+
+        return min_buf_size
+
+    # stop_after_attr_type is useful for calculating MESSAGE-DIGEST
+    def build(self, stop_after_attr_type=0):
+        attrs = bytearray()
+        for attr in self.attributes:
+            attrs.extend(attr.build())
+            if attr.attr_type == stop_after_attr_type:
+                break
+
+        message_type = bitwise_pack(self.method, 0, 11, 5)
+        message_type = bitwise_pack(self.msg_class, message_type, 1, 1)
+        message_type = bitwise_pack(self.method, message_type, 6, 3)
+        message_type = bitwise_pack(self.msg_class, message_type, 0, 1)
+        message_type = bitwise_pack(self.method, message_type, 3, 4)
+
+        message = pack(
+            (message_type, len(attrs), self.cookie, self.transaction_id),
+            self.__header_fmt,
+        )
+        message.extend(attrs)
+
+        return message
+
+    def add_error_code(self, code, phrase=None):
+        #      0                   1                   2                   3
+        #      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+        #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+        #     |           Reserved, should be 0         |Class|     Number    |
+        #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+        #     |      Reason Phrase (variable)                                ..
+        #     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+        error_code_fmt = [3, 1]
+        error_code = pack((code // 100, code % 100), error_code_fmt)
+        if phrase != None:
+            error_code.extend(bytearray(phrase, "utf-8"))
+        self.attributes.append(StunAttribute(ERROR_CODE, error_code))
+
+    #     0                   1                   2                   3
+    #     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    #    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    #    |x x x x x x x x|    Family     |         X-Port                |
+    #    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    #    |                X-Address (Variable)
+    #    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    __v4addr_fmt = [1, 1, 2, 4]
+    __v6addr_fmt = [1, 1, 2, 16]
+    __v4addr_size = reduce(operator.add, __v4addr_fmt)
+    __v6addr_size = reduce(operator.add, __v6addr_fmt)
+
+    def add_address(self, ip_address, version, port, attr_type):
+        if version == STUN_IPV4:
+            address = pack((0, STUN_IPV4, port, ip_address), self.__v4addr_fmt)
+        elif version == STUN_IPV6:
+            address = pack((0, STUN_IPV6, port, ip_address), self.__v6addr_fmt)
+        else:
+            raise ValueError("Invalid ip version: {}".format(version))
+        self.attributes.append(StunAttribute(attr_type, address))
+
+    def get_xaddr(self, ip_addr, version):
+        if version == STUN_IPV4:
+            return self.cookie ^ ip_addr
+        elif version == STUN_IPV6:
+            return ((self.cookie << 96) + self.transaction_id) ^ ip_addr
+        else:
+            raise ValueError("Invalid family: {}".format(version))
+
+    def get_xport(self, port):
+        return (self.cookie >> 16) ^ port
+
+    def add_xor_address(self, addr_port, attr_type):
+        ip_address = ipaddr.IPAddress(addr_port.host)
+        version = STUN_IPV6 if ip_address.version == 6 else STUN_IPV4
+        xaddr = self.get_xaddr(int(ip_address), version)
+        xport = self.get_xport(addr_port.port)
+        self.add_address(xaddr, version, xport, attr_type)
+
+    def add_data(self, buf):
+        self.attributes.append(StunAttribute(DATA_ATTR, buf))
+
+    def find(self, attr_type):
+        for attr in self.attributes:
+            if attr.attr_type == attr_type:
+                return attr
+        return None
+
+    def get_xor_address(self, attr_type):
+        addr_attr = self.find(attr_type)
+        if not addr_attr:
+            return None
+
+        padding, family, xport, xaddr = unpack(addr_attr.data, self.__v4addr_fmt)
+        addr_ctor = IPv4Address
+        if family == STUN_IPV6:
+            padding, family, xport, xaddr = unpack(addr_attr.data, self.__v6addr_fmt)
+            addr_ctor = IPv6Address
+        elif family != STUN_IPV4:
+            raise ValueError("Invalid family: {}".format(family))
+
+        return addr_ctor(
+            "UDP",
+            str(ipaddr.IPAddress(self.get_xaddr(xaddr, family))),
+            self.get_xport(xport),
+        )
+
+    def add_nonce(self, nonce):
+        self.attributes.append(StunAttribute(NONCE, bytearray(nonce, "utf-8")))
+
+    def add_realm(self, realm):
+        self.attributes.append(StunAttribute(REALM, bytearray(realm, "utf-8")))
+
+    def calculate_message_digest(self, username, realm, password):
+        digest_buf = self.build(MESSAGE_INTEGRITY)
+        # Trim off the MESSAGE-INTEGRITY attr
+        digest_buf = digest_buf[: len(digest_buf) - 24]
+        password = passlib.utils.saslprep(six.text_type(password))
+        key_string = "{}:{}:{}".format(username, realm, password)
+        md5 = hashlib.md5()
+        md5.update(bytearray(key_string, "utf-8"))
+        key = md5.digest()
+        return bytearray(hmac.new(key, digest_buf, hashlib.sha1).digest())
+
+    def add_lifetime(self, lifetime):
+        self.attributes.append(StunAttribute(LIFETIME, pack_uint(lifetime, 4)))
+
+    def get_lifetime(self):
+        lifetime_attr = self.find(LIFETIME)
+        if not lifetime_attr:
+            return None
+        return unpack_uint(lifetime_attr.data[0:4])
+
+    def get_username(self):
+        username = self.find(USERNAME)
+        if not username:
+            return None
+        return str(username.data)
+
+    def add_message_integrity(self, username, realm, password):
+        dummy_value = bytearray([0] * 20)
+        self.attributes.append(StunAttribute(MESSAGE_INTEGRITY, dummy_value))
+        digest = self.calculate_message_digest(username, realm, password)
+        self.find(MESSAGE_INTEGRITY).data = digest
+
+    def add_alternate_server(self, host, port):
+        address = ipaddr.IPAddress(host)
+        version = STUN_IPV6 if address.version == 6 else STUN_IPV4
+        self.add_address(int(address), version, port, ALTERNATE_SERVER)
+
+
+class Allocation(protocol.DatagramProtocol):
+    """
+    Comprises the socket for a TURN allocation, a back-reference to the
+    transport we will forward received traffic on, the allocator's address and
+    username, the set of permissions for the allocation, and the allocation's
+    expiry.
+    """
+
+    def __init__(self, other_transport_handler, allocator_address, username):
+        self.permissions = set()  # str, int tuples
+        # Handler to use when sending stuff that arrives on the allocation
+        self.other_transport_handler = other_transport_handler
+        self.allocator_address = allocator_address
+        self.username = username
+        self.expiry = time.time()
+        self.port = reactor.listenUDP(0, self, interface=v4_address)
+
+    def datagramReceived(self, data, address):
+        host = address[0]
+        port = address[1]
+        if not host in self.permissions:
+            print(
+                "Dropping packet from {}:{}, no permission on allocation {}".format(
+                    host, port, self.transport.getHost()
+                )
+            )
+            return
+
+        data_indication = StunMessage()
+        data_indication.method = DATA_MSG
+        data_indication.msg_class = INDICATION
+        data_indication.transaction_id = random.getrandbits(96)
+
+        # Only handles UDP allocations. Doubtful that we need more than this.
+        data_indication.add_xor_address(
+            to_ipaddress("UDP", host, port), XOR_PEER_ADDRESS
+        )
+        data_indication.add_data(data)
+
+        self.other_transport_handler.write(
+            data_indication.build(), self.allocator_address
+        )
+
+    def close(self):
+        self.port.stopListening()
+        self.port = None
+
+
+class StunHandler(object):
+    """
+    Frames and handles STUN messages. This is the core logic of the TURN
+    server, along with Allocation.
+    """
+
+    def __init__(self, transport_handler):
+        self.client_address = None
+        self.data = bytearray()
+        self.transport_handler = transport_handler
+
+    def data_received(self, data, address):
+        self.data += data
+        while True:
+            stun_message = StunMessage()
+            parsed_len = stun_message.parse(self.data)
+            if parsed_len > len(self.data):
+                break
+            self.data = self.data[parsed_len:]
+
+            response = self.handle_stun(stun_message, address)
+            if response:
+                self.transport_handler.write(response, address)
+
+    def handle_stun(self, stun_message, address):
+        self.client_address = address
+        if stun_message.msg_class == INDICATION:
+            if stun_message.method == SEND:
+                self.handle_send_indication(stun_message)
+            else:
+                print(
+                    "Dropping unknown indication method: {}".format(stun_message.method)
+                )
+            return None
+
+        if stun_message.msg_class != REQUEST:
+            print("Dropping STUN response, method: {}".format(stun_message.method))
+            return None
+
+        if stun_message.method == BINDING:
+            return self.make_success_response(stun_message).build()
+        elif stun_message.method == ALLOCATE:
+            return self.handle_allocation(stun_message).build()
+        elif stun_message.method == REFRESH:
+            return self.handle_refresh(stun_message).build()
+        elif stun_message.method == CREATE_PERMISSION:
+            return self.handle_permission(stun_message).build()
+        else:
+            return self.make_error_response(
+                stun_message,
+                400,
+                ("Unsupported STUN request, method: {}".format(stun_message.method)),
+            ).build()
+
+    def get_allocation_tuple(self):
+        return (
+            self.client_address.host,
+            self.client_address.port,
+            self.transport_handler.transport.getHost().type,
+            self.transport_handler.transport.getHost().host,
+            self.transport_handler.transport.getHost().port,
+        )
+
+    def handle_allocation(self, request):
+        allocate_response = self.check_long_term_auth(request)
+        if allocate_response.msg_class == SUCCESS_RESPONSE:
+            if self.get_allocation_tuple() in allocations:
+                return self.make_error_response(
+                    request,
+                    437,
+                    (
+                        "Duplicate allocation request for tuple {}".format(
+                            self.get_allocation_tuple()
+                        )
+                    ),
+                )
+
+            allocation = Allocation(
+                self.transport_handler, self.client_address, request.get_username()
+            )
+
+            allocate_response.add_xor_address(
+                allocation.transport.getHost(), XOR_RELAYED_ADDRESS
+            )
+
+            lifetime = request.get_lifetime()
+            if lifetime == None:
+                return self.make_error_response(
+                    request, 400, "Missing lifetime attribute in allocation request"
+                )
+
+            lifetime = min(lifetime, 3600)
+            allocate_response.add_lifetime(lifetime)
+            allocation.expiry = time.time() + lifetime
+
+            allocate_response.add_message_integrity(turn_user, turn_realm, turn_pass)
+            allocations[self.get_allocation_tuple()] = allocation
+        return allocate_response
+
+    def handle_refresh(self, request):
+        refresh_response = self.check_long_term_auth(request)
+        if refresh_response.msg_class == SUCCESS_RESPONSE:
+            try:
+                allocation = allocations[self.get_allocation_tuple()]
+            except KeyError:
+                return self.make_error_response(
+                    request,
+                    437,
+                    (
+                        "Refresh request for non-existing allocation, tuple {}".format(
+                            self.get_allocation_tuple()
+                        )
+                    ),
+                )
+
+            if allocation.username != request.get_username():
+                return self.make_error_response(
+                    request,
+                    441,
+                    (
+                        "Refresh request with wrong user, exp {}, got {}".format(
+                            allocation.username, request.get_username()
+                        )
+                    ),
+                )
+
+            lifetime = request.get_lifetime()
+            if lifetime == None:
+                return self.make_error_response(
+                    request, 400, "Missing lifetime attribute in allocation request"
+                )
+
+            lifetime = min(lifetime, 3600)
+            refresh_response.add_lifetime(lifetime)
+            allocation.expiry = time.time() + lifetime
+
+            refresh_response.add_message_integrity(turn_user, turn_realm, turn_pass)
+        return refresh_response
+
+    def handle_permission(self, request):
+        permission_response = self.check_long_term_auth(request)
+        if permission_response.msg_class == SUCCESS_RESPONSE:
+            try:
+                allocation = allocations[self.get_allocation_tuple()]
+            except KeyError:
+                return self.make_error_response(
+                    request,
+                    437,
+                    (
+                        "No such allocation for permission request, tuple {}".format(
+                            self.get_allocation_tuple()
+                        )
+                    ),
+                )
+
+            if allocation.username != request.get_username():
+                return self.make_error_response(
+                    request,
+                    441,
+                    (
+                        "Permission request with wrong user, exp {}, got {}".format(
+                            allocation.username, request.get_username()
+                        )
+                    ),
+                )
+
+            # TODO: Handle multiple XOR-PEER-ADDRESS
+            peer_address = request.get_xor_address(XOR_PEER_ADDRESS)
+            if not peer_address:
+                return self.make_error_response(
+                    request, 400, "Missing XOR-PEER-ADDRESS on permission request"
+                )
+
+            permission_response.add_message_integrity(turn_user, turn_realm, turn_pass)
+            allocation.permissions.add(peer_address.host)
+
+        return permission_response
+
+    def handle_send_indication(self, indication):
+        try:
+            allocation = allocations[self.get_allocation_tuple()]
+        except KeyError:
+            print(
+                "Dropping send indication; no allocation for tuple {}".format(
+                    self.get_allocation_tuple()
+                )
+            )
+            return
+
+        peer_address = indication.get_xor_address(XOR_PEER_ADDRESS)
+        if not peer_address:
+            print("Dropping send indication, missing XOR-PEER-ADDRESS")
+            return
+
+        data_attr = indication.find(DATA_ATTR)
+        if not data_attr:
+            print("Dropping send indication, missing DATA")
+            return
+
+        if indication.find(DONT_FRAGMENT):
+            print("Dropping send indication, DONT-FRAGMENT set")
+            return
+
+        if not peer_address.host in allocation.permissions:
+            print(
+                "Dropping send indication, no permission for {} on tuple {}".format(
+                    peer_address.host, self.get_allocation_tuple()
+                )
+            )
+            return
+
+        allocation.transport.write(
+            data_attr.data, (peer_address.host, peer_address.port)
+        )
+
+    def make_success_response(self, request):
+        response = copy.deepcopy(request)
+        response.attributes = []
+        response.add_xor_address(self.client_address, XOR_MAPPED_ADDRESS)
+        response.msg_class = SUCCESS_RESPONSE
+        return response
+
+    def make_error_response(self, request, code, reason=None):
+        if reason:
+            print("{}: rejecting with {}".format(reason, code))
+        response = copy.deepcopy(request)
+        response.attributes = []
+        response.add_error_code(code, reason)
+        response.msg_class = ERROR_RESPONSE
+        return response
+
+    def make_challenge_response(self, request, reason=None):
+        response = self.make_error_response(request, 401, reason)
+        # 65 means the hex encoding will need padding half the time
+        response.add_nonce("{:x}".format(random.getrandbits(65)))
+        response.add_realm(turn_realm)
+        return response
+
+    def check_long_term_auth(self, request):
+        message_integrity = request.find(MESSAGE_INTEGRITY)
+        if not message_integrity:
+            return self.make_challenge_response(request)
+
+        username = request.find(USERNAME)
+        realm = request.find(REALM)
+        nonce = request.find(NONCE)
+        if not username or not realm or not nonce:
+            return self.make_error_response(
+                request, 400, "Missing either USERNAME, NONCE, or REALM"
+            )
+
+        if username.data.decode("utf-8") != turn_user:
+            return self.make_challenge_response(
+                request, "Wrong user {}, exp {}".format(username.data, turn_user)
+            )
+
+        expected_message_digest = request.calculate_message_digest(
+            turn_user, turn_realm, turn_pass
+        )
+        if message_integrity.data != expected_message_digest:
+            return self.make_challenge_response(request, "Incorrect message disgest")
+
+        return self.make_success_response(request)
+
+
+class StunRedirectHandler(StunHandler):
+    """
+    Frames and handles STUN messages by redirecting to the "real" server port.
+    Performs the redirect with auth, so does a 401 to unauthed requests.
+    Can be used to test port-based redirect handling.
+    """
+
+    def __init__(self, transport_handler):
+        super(StunRedirectHandler, self).__init__(transport_handler)
+
+    def handle_stun(self, stun_message, address):
+        self.client_address = address
+        if stun_message.msg_class == REQUEST:
+            challenge_response = self.check_long_term_auth(stun_message)
+
+            if challenge_response.msg_class == SUCCESS_RESPONSE:
+                return self.make_redirect_response(stun_message).build()
+
+            return challenge_response.build()
+
+    def make_redirect_response(self, request):
+        response = self.make_error_response(request, 300, "Try alternate")
+        port = STUN_PORT
+        if self.transport_handler.transport.getHost().port == TURNS_REDIRECT_PORT:
+            port = STUNS_PORT
+
+        response.add_alternate_server(
+            self.transport_handler.transport.getHost().host, port
+        )
+
+        response.add_message_integrity(turn_user, turn_realm, turn_pass)
+        return response
+
+
+class UdpStunHandler(protocol.DatagramProtocol):
+    """
+    Represents a UDP listen port for TURN.
+    """
+
+    def datagramReceived(self, data, address):
+        stun_handler = StunHandler(self)
+        stun_handler.data_received(data, to_ipaddress("UDP", address[0], address[1]))
+
+    def write(self, data, address):
+        self.transport.write(bytes(data), (address.host, address.port))
+
+
+class UdpStunRedirectHandler(protocol.DatagramProtocol):
+    """
+    Represents a UDP listen port for TURN that will redirect.
+    """
+
+    def datagramReceived(self, data, address):
+        stun_handler = StunRedirectHandler(self)
+        stun_handler.data_received(data, to_ipaddress("UDP", address[0], address[1]))
+
+    def write(self, data, address):
+        self.transport.write(bytes(data), (address.host, address.port))
+
+
+class TcpStunHandlerFactory(protocol.Factory):
+    """
+    Represents a TCP listen port for TURN.
+    """
+
+    def buildProtocol(self, addr):
+        return TcpStunHandler(addr)
+
+
+class TcpStunHandler(protocol.Protocol):
+    """
+    Represents a connected TCP port for TURN.
+    """
+
+    def __init__(self, addr):
+        self.address = addr
+        self.stun_handler = None
+
+    def dataReceived(self, data):
+        # This needs to persist, since it handles framing
+        if not self.stun_handler:
+            self.stun_handler = StunHandler(self)
+        self.stun_handler.data_received(data, self.address)
+
+    def connectionLost(self, reason):
+        print("Lost connection from {}".format(self.address))
+        # Destroy allocations that this connection made
+        keys_to_delete = []
+        for key, allocation in allocations.items():
+            if allocation.other_transport_handler == self:
+                print("Closing allocation due to dropped connection: {}".format(key))
+                keys_to_delete.append(key)
+                allocation.close()
+
+        for key in keys_to_delete:
+            del allocations[key]
+
+    def write(self, data, address):
+        self.transport.write(bytes(data))
+
+
+class TcpStunRedirectHandlerFactory(protocol.Factory):
+    """
+    Represents a TCP listen port for TURN that will redirect.
+    """
+
+    def buildProtocol(self, addr):
+        return TcpStunRedirectHandler(addr)
+
+
+class TcpStunRedirectHandler(protocol.DatagramProtocol):
+    def __init__(self, addr):
+        self.address = addr
+        self.stun_handler = None
+
+    def dataReceived(self, data):
+        # This needs to persist, since it handles framing. Framing matters here
+        # because we do a round of auth before redirecting.
+        if not self.stun_handler:
+            self.stun_handler = StunRedirectHandler(self)
+        self.stun_handler.data_received(data, self.address)
+
+    def write(self, data, address):
+        self.transport.write(bytes(data))
+
+
+def get_default_route(family):
+    dummy_socket = socket.socket(family, socket.SOCK_DGRAM)
+    if family is socket.AF_INET:
+        dummy_socket.connect(("8.8.8.8", 53))
+    else:
+        dummy_socket.connect(("2001:4860:4860::8888", 53))
+
+    default_route = dummy_socket.getsockname()[0]
+    dummy_socket.close()
+    return default_route
+
+
+turn_user = "foo"
+turn_pass = "bar"
+turn_realm = "mozilla.invalid"
+allocations = {}
+v4_address = get_default_route(socket.AF_INET)
+try:
+    v6_address = get_default_route(socket.AF_INET6)
+except:
+    v6_address = ""
+
+
+def prune_allocations():
+    now = time.time()
+    keys_to_delete = []
+    for key, allocation in allocations.items():
+        if allocation.expiry < now:
+            print("Allocation expired: {}".format(key))
+            keys_to_delete.append(key)
+            allocation.close()
+
+    for key in keys_to_delete:
+        del allocations[key]
+
+
+CERT_FILE = "selfsigned.crt"
+KEY_FILE = "private.key"
+
+
+def create_self_signed_cert(name):
+    from OpenSSL import crypto
+
+    if os.path.isfile(CERT_FILE) and os.path.isfile(KEY_FILE):
+        return
+
+    # create a key pair
+    k = crypto.PKey()
+    k.generate_key(crypto.TYPE_RSA, 1024)
+
+    # create a self-signed cert
+    cert = crypto.X509()
+    cert.get_subject().C = "US"
+    cert.get_subject().ST = "TX"
+    cert.get_subject().L = "Dallas"
+    cert.get_subject().O = "Mozilla test iceserver"
+    cert.get_subject().OU = "Mozilla test iceserver"
+    cert.get_subject().CN = name
+    cert.set_serial_number(1000)
+    cert.gmtime_adj_notBefore(0)
+    cert.gmtime_adj_notAfter(10 * 365 * 24 * 60 * 60)
+    cert.set_issuer(cert.get_subject())
+    cert.set_pubkey(k)
+    cert.add_extensions(
+        [crypto.X509Extension(b"subjectAltName", False, f"DNS:{name}".encode())]
+    )
+    cert.sign(k, "sha1")
+
+    open(CERT_FILE, "wb").write(crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
+    open(KEY_FILE, "wb").write(crypto.dump_privatekey(crypto.FILETYPE_PEM, k))
+
+
+if __name__ == "__main__":
+    random.seed()
+
+    if platform.system() == "Windows":
+        # Windows is finicky about allowing real interfaces to talk to loopback.
+        interface_4 = v4_address
+        interface_6 = v6_address
+        hostname = socket.gethostname()
+    else:
+        # Our linux builders do not have a hostname that resolves to the real
+        # interface.
+        interface_4 = "127.0.0.1"
+        interface_6 = "::1"
+        hostname = "localhost"
+
+    reactor.listenUDP(STUN_PORT, UdpStunHandler(), interface=interface_4)
+    reactor.listenTCP(STUN_PORT, TcpStunHandlerFactory(), interface=interface_4)
+
+    reactor.listenUDP(
+        TURN_REDIRECT_PORT, UdpStunRedirectHandler(), interface=interface_4
+    )
+    reactor.listenTCP(
+        TURN_REDIRECT_PORT, TcpStunRedirectHandlerFactory(), interface=interface_4
+    )
+
+    try:
+        reactor.listenUDP(STUN_PORT, UdpStunHandler(), interface=interface_6)
+        reactor.listenTCP(STUN_PORT, TcpStunHandlerFactory(), interface=interface_6)
+
+        reactor.listenUDP(
+            TURN_REDIRECT_PORT, UdpStunRedirectHandler(), interface=interface_6
+        )
+        reactor.listenTCP(
+            TURN_REDIRECT_PORT, TcpStunRedirectHandlerFactory(), interface=interface_6
+        )
+    except:
+        pass
+
+    try:
+        from twisted.internet import ssl
+        from OpenSSL import SSL
+
+        create_self_signed_cert(hostname)
+        tls_context_factory = ssl.DefaultOpenSSLContextFactory(
+            KEY_FILE, CERT_FILE, SSL.TLSv1_2_METHOD
+        )
+        reactor.listenSSL(
+            STUNS_PORT,
+            TcpStunHandlerFactory(),
+            tls_context_factory,
+            interface=interface_4,
+        )
+
+        try:
+            reactor.listenSSL(
+                STUNS_PORT,
+                TcpStunHandlerFactory(),
+                tls_context_factory,
+                interface=interface_6,
+            )
+
+            reactor.listenSSL(
+                TURNS_REDIRECT_PORT,
+                TcpStunRedirectHandlerFactory(),
+                tls_context_factory,
+                interface=interface_6,
+            )
+        except:
+            pass
+
+        f = open(CERT_FILE, "r")
+        lines = f.readlines()
+        lines.pop(0)  # Remove BEGIN CERTIFICATE
+        lines.pop()  # Remove END CERTIFICATE
+        # pylint --py3k: W1636 W1649
+        lines = list(map(str.strip, lines))
+        certbase64 = "".join(lines)  # pylint --py3k: W1649
+
+        turns_url = ', "turns:' + hostname + '"'
+        cert_prop = ', "cert":"' + certbase64 + '"'
+    except:
+        turns_url = ""
+        cert_prop = ""
+        pass
+
+    allocation_pruner = LoopingCall(prune_allocations)
+    allocation_pruner.start(1)
+
+    template = Template(
+        '[\
+{"urls":["stun:$hostname", "stun:$hostname?transport=tcp"]}, \
+{"username":"$user","credential":"$pwd","turn_redirect_port":"$TURN_REDIRECT_PORT","turns_redirect_port":"$TURNS_REDIRECT_PORT","urls": \
+["turn:$hostname", "turn:$hostname?transport=tcp" $turns_url] \
+$cert_prop}]'  # Hack to make it easier to override cert checks
+    )
+
+    print(
+        template.substitute(
+            user=turn_user,
+            pwd=turn_pass,
+            hostname=hostname,
+            turns_url=turns_url,
+            cert_prop=cert_prop,
+            TURN_REDIRECT_PORT=TURN_REDIRECT_PORT,
+            TURNS_REDIRECT_PORT=TURNS_REDIRECT_PORT,
+        )
+    )
+
+    reactor.run()