#!/usr/bin/env python2
DOCUMENTATION = '''
---
module: hardware_facts
short_description: "check if at least one SAT>IP server responds on the network"
description:
     - This script sends a multicast message and awaits responses by Sat>IP servers.
       Returns the boolean variable 'satip_detected'
'''
EXAMPLES = '''
- name: "detect SAT>IP Server on the network"
  action: satip_facts

- debug:
    var: satip_detected
'''

import json
import socket
import sys
import time

from ansible.module_utils.basic import *

SSDP_ADDR = "239.255.255.250"
SSDP_PORT = 1900
# SSDP_MX = max delay for server response
# a value of 2s is recommended by the SAT>IP specification 1.2.2
SSDP_MX = 2
SSDP_ST = "urn:ses-com:device:SatIPServer:1"

ssdpRequest = "\r\n".join((
    "M-SEARCH * HTTP/1.1",
    "HOST: %s:%d" % (SSDP_ADDR, SSDP_PORT),
    "MAN: \"ssdp:discover\"",
    "MX: %d" % (SSDP_MX),
    "ST: %s" % (SSDP_ST),
    "\r\n"))

def main():
    module = AnsibleModule(argument_spec={}, supports_check_mode=True,)
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    # according to Sat>IP Specification 1.2.2, p. 20
    # a client should send three requests within 100 ms with a ttl of 2
    sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
    sock.settimeout(SSDP_MX + 0.5)
    for _ in range(3):
        sock.sendto(ssdpRequest, (SSDP_ADDR, SSDP_PORT))
        time.sleep(0.03)
    try:
        response = sock.recv(1000)
        if response and "SERVER:" in response:
            got_response = True
        else:
            raise ValueError('No satip server detected')
    except (socket.timeout, ValueError):
        got_response = False

    module.exit_json(changed=False, ansible_facts={'satip_detected': got_response})

if __name__ == '__main__':  
    main()