2017-03-02 09:06:19 +01:00
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#!/usr/bin/env python3
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# This script sends a multicast message and awaits responses by Sat>IP servers.
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# returns the boolean variable 'satip_detected' as json
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import json
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import socket
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import sys
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import time
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2017-03-01 21:13:03 +01:00
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2017-03-02 09:06:19 +01:00
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SSDP_ADDR = "239.255.255.250"
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SSDP_PORT = 1900
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# SSDP_MX = max delay for server response
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# a value of 2s is recommended by the SAT>IP specification 1.2.2
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SSDP_MX = 2
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SSDP_ST = "urn:ses-com:device:SatIPServer:1"
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2017-03-01 21:13:03 +01:00
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2017-03-02 09:06:19 +01:00
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ssdpRequest = "\r\n".join((
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"M-SEARCH * HTTP/1.1",
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"HOST: %s:%d" % (SSDP_ADDR, SSDP_PORT),
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"MAN: \"ssdp:discover\"",
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"MX: %d" % (SSDP_MX),
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"ST: %s" % (SSDP_ST),
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"\r\n"))
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2017-03-01 21:13:03 +01:00
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2017-03-02 09:06:19 +01:00
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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# according to Sat>IP Specification 1.2.2, p. 20
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# a client should send three requests within 100 ms with a ttl of 2
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sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 2)
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sock.settimeout(SSDP_MX + 0.5)
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for _ in range(3):
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sock.sendto(ssdpRequest.encode('ascii'), (SSDP_ADDR, SSDP_PORT))
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time.sleep(0.03)
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try:
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response = sock.recv(1000).decode()
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if response and "SERVER:" in response:
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got_response = True
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else:
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raise ValueError('No satip server detected')
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except (socket.timeout, ValueError):
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got_response = False
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finally:
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print(json.dumps(
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{'satip_detected': got_response}
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))
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