dpp-nfc: Collision detection for handover request

Address possible handover request collisions for cases where both
devices try to initiate handover simultaneously.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2020-05-15 02:26:01 +03:00 committed by Jouni Malinen
parent 9ad3fe9343
commit 1e0bc897ab

View file

@ -8,6 +8,7 @@
# See README for more details.
import os
import struct
import sys
import time
import threading
@ -33,6 +34,8 @@ continue_loop = True
terminate_now = False
summary_file = None
success_file = None
my_crn = None
peer_crn = None
def summary(txt):
print(txt)
@ -209,11 +212,16 @@ def dpp_handover_client(llc):
uri = ndef.UriRecord(uri)
print("NFC URI record for DPP: " + str(uri))
carrier = ndef.Record('application/vnd.wfa.dpp', 'A', uri.data)
hr = ndef.HandoverRequestRecord(version="1.4", crn=os.urandom(2))
crn = os.urandom(2)
hr = ndef.HandoverRequestRecord(version="1.4", crn=crn)
hr.add_alternative_carrier('active', carrier.name)
message = [hr, carrier]
print("NFC Handover Request message for DPP: " + str(message))
global peer_crn
if peer_crn is not None:
print("NFC handover request from peer was already received - do not send own")
return
client = nfc.handover.HandoverClient(llc)
try:
summary("Trying to initiate NFC connection handover")
@ -228,6 +236,11 @@ def dpp_handover_client(llc):
client.close()
return
if peer_crn is not None:
print("NFC handover request from peer was already received - do not send own")
client.close()
return
summary("Sending handover request")
if not client.send_records(message):
@ -235,6 +248,9 @@ def dpp_handover_client(llc):
client.close()
return
global my_crn
my_crn, = struct.unpack('>H', crn)
summary("Receiving handover response")
message = client.recv_records(timeout=3.0)
if message is None:
@ -335,7 +351,32 @@ class HandoverServer(nfc.handover.HandoverServer):
clear_raw_mode()
print("\nHandoverServer - request received: " + str(records))
carrier = None
global my_crn, peer_crn
for carrier in records:
if not isinstance(carrier, ndef.HandoverRequestRecord):
continue
if carrier.collision_resolution_number:
peer_crn = carrier.collision_resolution_number
print("peer_crn:", peer_crn)
if my_crn is not None:
print("my_crn:", my_crn)
if my_crn is not None and peer_crn is not None:
if my_crn == peer_crn:
print("Same crn used - automatic collision resolution failed")
# TODO: Should generate a new Handover Request message
return ''
if ((my_crn & 1) == (peer_crn & 1) and my_crn > peer_crn) or \
((my_crn & 1) != (peer_crn & 1) and my_crn < peer_crn):
print("I'm the Handover Selector Device")
pass
else:
print("Peer is the Handover Selector device")
print("Ignore the received request.")
return ''
hs = ndef.HandoverSelectRecord('1.4')
sel = [hs]
@ -362,7 +403,6 @@ class HandoverServer(nfc.handover.HandoverServer):
continue
found = True
self.received_carrier = carrier
wpas = wpas_connect()
if wpas is None:
@ -585,8 +625,10 @@ def llcp_startup(llc):
def llcp_connected(llc):
print("P2P LLCP connected")
global wait_connection
global wait_connection, my_crn, peer_crn
wait_connection = False
my_crn = None
peer_crn = None
global srv
srv.start()
if init_on_touch or not no_input: