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7c7d509017
The echo server was using the wrong socket options, allowing responses to be fragmented. Since we use the echo server for MTU discovery, that would have beaten the purpose. Also includes minor formatting fixes.
98 lines
3.5 KiB
Python
98 lines
3.5 KiB
Python
#
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# Copyright 2017 Ettus Research, National Instruments Company
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#
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# SPDX-License-Identifier: GPL-3.0
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#
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"""
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Code to run the discovery port
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"""
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from __future__ import print_function
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from multiprocessing import Process
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import socket
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from builtins import bytes
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from six import iteritems
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from usrp_mpm.mpmtypes import MPM_DISCOVERY_PORT
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from usrp_mpm.mpmlog import get_main_logger
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RESPONSE_PREAMBLE = "USRP-MPM"
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RESPONSE_SEP = ";"
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RESPONSE_CLAIMED_KEY = "claimed"
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# "Max MTU" is not a redundant name. We don't know the total path MTU, but we
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# can say for sure that it won't exceed a certain value, and that's the max MTU
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MAX_MTU = 8000
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# For setsockopt
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IP_MTU_DISCOVER = 10
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IP_PMTUDISC_DO = 2
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def spawn_discovery_process(device_info, shared_state, discovery_addr):
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"""
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Returns a process that contains the device discovery.
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Arguments:
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device_info -- A dictionary of type string -> string. All of these items
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will be included in the response string.
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shared_state -- Shared state of device (is it claimed, etc.). Is a
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SharedState() object.
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discovery_addr -- Discovery will listen on this address(es)
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"""
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proc = Process(
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target=_discovery_process,
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args=(device_info, shared_state, discovery_addr)
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)
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proc.start()
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return proc
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def _discovery_process(device_info, state, discovery_addr):
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"""
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The actual process for device discovery. Is spawned by
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spawn_discovery_process().
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"""
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def create_response_string():
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" Generate the string that gets sent back to the requester. "
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return RESPONSE_SEP.join(
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[RESPONSE_PREAMBLE] + \
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["{k}={v}".format(k=k, v=v) for k, v in iteritems(device_info)] + \
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["{k}={v}".format(k=RESPONSE_CLAIMED_KEY, v=state.claim_status.value)]
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)
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log = get_main_logger().getChild('discovery')
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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# FIXME really, we should only bind to the subnet but I haven't gotten that
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# working yet
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sock.bind((("0.0.0.0", MPM_DISCOVERY_PORT)))
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send_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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send_sock.setsockopt(socket.IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DO)
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# TODO yeah I know that's not how you do this
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discovery_addr_prefix = discovery_addr.replace('.255', '')
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if discovery_addr == '0.0.0.0':
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discovery_addr_prefix = ''
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try:
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while True:
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data, sender = sock.recvfrom(MAX_MTU)
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log.info("Got poked by: %s", sender[0])
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# TODO this is still part of the awful subnet identification
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if not sender[0].startswith(discovery_addr_prefix):
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continue
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if data.strip(b"\0") == b"MPM-DISC":
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log.info("Sending discovery response to %s port: %d",
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sender[0], sender[1])
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send_data = bytes(create_response_string(), 'ascii')
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log.info(send_data)
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send_sock.sendto(send_data, sender)
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elif data.strip(b"\0").startswith(b"MPM-ECHO"):
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log.info("Received echo request from {sender}"
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.format(sender=sender[0]))
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send_data = data
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try:
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send_sock.sendto(send_data, sender)
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except OSError as ex:
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log.debug("ECHO send error: %s", str(ex))
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except Exception as err:
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log.error("Unexpected error: `%s' Type: `%s'", str(err), type(err))
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sock.close()
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send_sock.close()
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exit(1)
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