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