Tiny python SSDP discovery library with no external dependencies - Python 2 & 3 compatible

ssdp.py

#   Copyright 2014 Dan Krause
#
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#   Unless required by applicable law or agreed to in writing, software
#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
#   limitations under the License.

import sys
import socket
try:
    from http.client import HTTPResponse
except ImportError:
    from httplib import HTTPResponse

class SSDPResponse(object):
    def __init__(self, sock):
        r = HTTPResponse(sock)
        r.begin()
        self.location = r.getheader("location")
        self.usn = r.getheader("usn")
        self.st = r.getheader("st")
        self.cache = r.getheader("cache-control").split("=")[1]

    def __repr__(self):
        return "<SSDPResponse({location}, {st}, {usn})>".format(**self.__dict__)

def discover(service, timeout=2, retries=1, source_ip=None):
    group = ("239.255.255.250", 1900)
    message = "\r\n".join([
        'M-SEARCH * HTTP/1.1',
        'HOST: {0}:{1}',
        'MAN: "ssdp:discover"',
        'ST: {st}',
        'MX: 3','',''
    ])
    socket.setdefaulttimeout(timeout)
    responses = {}

    for _ in range(retries):
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        if source_ip:
            sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton(source_ip))
        sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
        sock.sendto(message.format(*group, st=service).encode(), group)

        print("SSDP Searching for %s from %s" % (service, source_ip or "any"))
        while True:
            try:
                yield SSDPResponse(sock)
            except socket.timeout:
                break


SERVICE_TYPES = [
	"urn:schemas-upnp-org:device:InternetGatewayDevice:2",
	"urn:schemas-upnp-org:service:WANIPConnection:2",
	"urn:schemas-upnp-org:device:InternetGatewayDevice:1",
	"urn:schemas-upnp-org:service:WANIPConnection:1",
	"urn:schemas-upnp-org:service:WANPPPConnection:1",
	"upnp:rootdevice",
	"ssdp:all",
]

if __name__ == "__main__":
    source = None
    if len(sys.argv) > 1:
        source = sys.argv[1]

    for st in SERVICE_TYPES:
        for rep in discover(st, timeout=2, source_ip=source):
            print("  FOUND %s" % rep)