[tests] verify a Router can establish links quickly via multicast Link Request (#7807)

This commit adds a test to make sure delay sending multicast Link
Request (#7745) works as intended.

tests/scripts/thread-cert/test_router_multicast_link_request.py

@@ -0,0 +1,140 @@
+#!/usr/bin/env python3
+#
+#  Copyright (c) 2022, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+import logging
+import unittest
+
+import config
+import thread_cert
+from pktverify.consts import MLE_LINK_REQUEST, MLE_LINK_ACCEPT
+from pktverify.packet_verifier import PacketVerifier
+
+LEADER = 1
+REED = 2
+ROUTER1, ROUTER2, ROUTER3 = 3, 4, 5
+
+# Test Purpose and Description:
+# -----------------------------
+# This test verifies if a device can quickly and efficiently establish links with
+# neighboring routers by sending a multicast Link Request message after becoming
+# a router
+#
+# Test Topology:
+# -------------
+#     Leader------+
+#    |     \       \
+# Router1 Router2 Router3
+#    \     |        |
+#     +---REED-----+
+#
+
+# REED should establish links to the three Routers within the delay threshold.
+# The max delay consists:
+#   Leader may delay 1 second for MLE Advertisement
+#   Router may delay 1 second for MLE Advertisement
+#   Router may delay 1 second for MLE Link Accept after receiving MLE Link Request (multicast)
+LINK_ESTABLISH_DELAY_THRESHOLD = 3
+
+
+class TestRouterMulticastLinkRequest(thread_cert.TestCase):
+    USE_MESSAGE_FACTORY = False
+
+    TOPOLOGY = {
+        LEADER: {
+            'name': 'LEADER',
+            'mode': 'rdn',
+            'allowlist': [ROUTER1, ROUTER2, ROUTER3]
+        },
+        ROUTER1: {
+            'name': 'ROUTER1',
+            'mode': 'rdn',
+            'allowlist': [LEADER, REED]
+        },
+        ROUTER2: {
+            'name': 'ROUTER2',
+            'mode': 'rdn',
+            'allowlist': [LEADER, REED]
+        },
+        ROUTER3: {
+            'name': 'ROUTER3',
+            'mode': 'rdn',
+            'allowlist': [LEADER, REED]
+        },
+        REED: {
+            'name': 'REED',
+            'mode': 'rdn',
+            'allowlist': [ROUTER1, ROUTER2, ROUTER3]
+        },
+    }
+
+    def test(self):
+        self.nodes[LEADER].start()
+        self.simulator.go(5)
+        self.assertEqual(self.nodes[LEADER].get_state(), 'leader')
+
+        for routerid in (ROUTER1, ROUTER2, ROUTER3):
+            self.nodes[routerid].start()
+            self.simulator.go(config.ROUTER_STARTUP_DELAY)
+            self.assertEqual(self.nodes[routerid].get_state(), 'router')
+
+        # Wait for the network to stabilize
+        self.simulator.go(60)
+
+        self.nodes[REED].start()
+        self.simulator.go(config.ROUTER_STARTUP_DELAY)
+        self.assertEqual(self.nodes[REED].get_state(), 'router')
+        self.simulator.go(LINK_ESTABLISH_DELAY_THRESHOLD + 3)
+
+    def verify(self, pv: PacketVerifier):
+        pkts = pv.pkts
+        print(pv.vars)
+        pv.summary.show()
+
+        REED = pv.vars['REED']
+        as_pkt = pkts.filter_wpan_src64(REED).filter_coap_request('/a/as', confirmable=True).must_next()
+        parent_rloc16 = as_pkt.wpan.dst16
+        as_ack_pkt = pkts.filter_wpan_src16(parent_rloc16).filter_coap_ack('/a/as').must_next()
+        become_router_timestamp = as_ack_pkt.sniff_timestamp
+
+        # REED has just received `/a/as` and become a Router
+        # REED should send Multicast Link Request after becoming Router
+        link_request_pkt = pkts.filter_wpan_src64(REED).filter_mle_cmd(MLE_LINK_REQUEST).must_next()
+        link_request_pkt.must_verify('ipv6.dst == "ff02::2"')
+
+        # REED should send Link Accept to the three Routers
+        for router in ('ROUTER1', 'ROUTER2', 'ROUTER3'):
+            with pkts.save_index():
+                pkt = pkts.filter_wpan_src64(REED).filter_wpan_dst64(
+                    pv.vars[router]).filter_mle_cmd(MLE_LINK_ACCEPT).must_next()
+                link_establish_delay = pkt.sniff_timestamp - become_router_timestamp
+                logging.info("Link to %s established in %.3f seconds", router, link_establish_delay)
+                self.assertLess(link_establish_delay, LINK_ESTABLISH_DELAY_THRESHOLD)
+
+
+if __name__ == '__main__':
+    unittest.main()