[mesh-forwarder] update forwarding messages to ALOC destination (#10419)

This commit updates how messages with an ALOC destination are
forwarded. If the chosen ALOC destination is a child, its parent is
used as the mesh destination unless the device itself is the parent.
Additionally, if the selected ALOC destination is a sleepy child of
the device, the parent node ensures to prepare the message for
indirect transmission. These changes ensure correct forwarding to ED
or SED devices when they register a service and want to receive
messages on their service ALOC.

This commit also adds a new test, `test-030-anycast-forwarding.py`,
which validates the forwarding to ALOC addresses on both ED and SED
devices.

src/core/thread/mesh_forwarder.cpp

@@ -628,6 +628,15 @@ Message *MeshForwarder::PrepareNextDirectTransmission(void)
         switch (error)
         {
         case kErrorNone:
+            if (!curMessage->IsDirectTransmission())
+            {
+                // Skip if message is no longer marked for direct transmission.
+                // For example, `UpdateIp6Route()` may determine the destination
+                // is an ALOC associated with an SED child of this device and
+                // mark it for indirect tx to the SED child.
+                continue;
+            }
+
 #if OPENTHREAD_CONFIG_TX_QUEUE_STATISTICS_ENABLE
             mTxQueueStats.UpdateFor(*curMessage);
 #endif

src/core/thread/mesh_forwarder_ftd.cpp

@@ -424,7 +424,6 @@ Error MeshForwarder::AnycastRouteLookup(uint8_t aServiceId, AnycastType aType, u
     NetworkData::Iterator iterator = NetworkData::kIteratorInit;
     uint8_t               bestCost = Mle::kMaxRouteCost;
     uint16_t              bestDest = Mac::kShortAddrInvalid;
-    uint8_t               routerId;
 
     switch (aType)
     {
@@ -485,13 +484,18 @@ Error MeshForwarder::AnycastRouteLookup(uint8_t aServiceId, AnycastType aType, u
     }
     }
 
-    routerId = Mle::RouterIdFromRloc16(bestDest);
-
-    if (!(Mle::IsRouterRloc16(bestDest) || Mle::Rloc16FromRouterId(routerId) == Get<Mle::MleRouter>().GetRloc16()))
+    if (Mle::IsChildRloc16(bestDest))
     {
-        // if agent is neither active router nor child of this device
-        // use the parent of the ED Agent as Dest
-        bestDest = Mle::Rloc16FromRouterId(routerId);
+        // If the selected destination is a child, we use its parent
+        // as the destination unless the device itself is the
+        // parent of the `bestDest`.
+
+        uint16_t bestDestParent = Mle::Rloc16FromRouterId(Mle::RouterIdFromRloc16(bestDest));
+
+        if (Get<Mle::Mle>().GetRloc16() != bestDestParent)
+        {
+            bestDest = bestDestParent;
+        }
     }
 
     aMeshDest = bestDest;
@@ -556,6 +560,23 @@ Error MeshForwarder::UpdateIp6RouteFtd(const Ip6::Header &aIp6Header, Message &a
         {
             ExitNow(error = kErrorDrop);
         }
+
+        // If the selected ALOC destination, `mMeshDest`, is a sleepy
+        // child of this device, prepare the message for indirect tx
+        // to the sleepy child and un-mark message for direct tx.
+
+        if (mle.IsRouterOrLeader() && Mle::IsChildRloc16(mMeshDest) && Mle::RouterIdMatch(mMeshDest, mle.GetRloc16()))
+        {
+            Child *child = Get<ChildTable>().FindChild(mMeshDest, Child::kInStateValid);
+
+            VerifyOrExit(child != nullptr, error = kErrorDrop);
+
+            if (!child->IsRxOnWhenIdle())
+            {
+                mIndirectSender.AddMessageForSleepyChild(aMessage, *child);
+                aMessage.ClearDirectTransmission();
+            }
+        }
     }
     else if ((neighbor = Get<NeighborTable>().FindNeighbor(aIp6Header.GetDestination())) != nullptr)
     {

tests/toranj/cli/test-030-anycast-forwarding.py

@@ -0,0 +1,151 @@
+#!/usr/bin/env python3
+#
+#  Copyright (c) 2024, 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.
+
+from cli import verify
+from cli import verify_within
+import cli
+import time
+
+# -----------------------------------------------------------------------------------------------------------------------
+# Test description: ALOC address forwarding to ED and SED devices.
+#
+# Network topology
+#
+#    r1 ---- r2 ---- r3
+#                    /|\
+#                   / | \
+#                 ed sed sed2
+#
+
+test_name = __file__[:-3] if __file__.endswith('.py') else __file__
+print('-' * 120)
+print('Starting \'{}\''.format(test_name))
+
+# -----------------------------------------------------------------------------------------------------------------------
+# Creating `cli.Node` instances
+
+speedup = 40
+cli.Node.set_time_speedup_factor(speedup)
+
+r1 = cli.Node()
+r2 = cli.Node()
+r3 = cli.Node()
+ed = cli.Node()
+sed = cli.Node()
+sed2 = cli.Node()
+
+nodes = [r1, r2, r3, ed, sed, sed2]
+
+# -----------------------------------------------------------------------------------------------------------------------
+# Form topology
+
+r1.allowlist_node(r2)
+
+r2.allowlist_node(r1)
+r2.allowlist_node(r3)
+
+r3.allowlist_node(r2)
+r3.allowlist_node(ed)
+r3.allowlist_node(sed)
+r3.allowlist_node(sed2)
+
+ed.allowlist_node(r3)
+sed.allowlist_node(r3)
+sed2.allowlist_node(r3)
+
+r1.form('aloc')
+r2.join(r1)
+r3.join(r2)
+ed.join(r2, cli.JOIN_TYPE_END_DEVICE)
+sed.join(r3, cli.JOIN_TYPE_SLEEPY_END_DEVICE)
+sed2.join(r3, cli.JOIN_TYPE_SLEEPY_END_DEVICE)
+
+sed.set_pollperiod(400)
+sed2.set_pollperiod(500)
+
+verify(r1.get_state() == 'leader')
+verify(r2.get_state() == 'router')
+verify(r3.get_state() == 'router')
+verify(ed.get_state() == 'child')
+verify(sed.get_state() == 'child')
+verify(sed.get_state() == 'child')
+
+sed.set_mode('n')
+
+for child in [ed, sed, sed2]:
+    verify(int(child.get_parent_info()['Rloc'], 16) == int(r3.get_rloc16(), 16))
+
+# -----------------------------------------------------------------------------------------------------------------------
+# Test Implementation
+
+
+def check_netdata_services(expected_num_services):
+    # Check that all nodes see the `expected_num_services` service
+    # entries in network data.
+    for node in nodes:
+        verify(len(node.get_netdata_services()) == expected_num_services)
+
+
+wait_time = 5
+
+# Add a service on ed which is non-sleepy child.
+
+ed.cli('service add 44970 11 00')
+ed.register_netdata()
+
+verify_within(check_netdata_services, wait_time, 1)
+
+# Verify that the ALOC associated with a non-sleepy child's service is
+# pingable from all nodes.
+
+aloc1 = r1.get_mesh_local_prefix().split('/')[0] + 'ff:fe00:fc10'
+
+for node in nodes:
+    node.ping(aloc1)
+
+# Add a service now from `sed` which is a sleepy child and again make sure
+# its ALOC can be pinged from all other nodes.
+
+sed.cli('service add 44970 22 00')
+sed.register_netdata()
+
+verify_within(check_netdata_services, wait_time, 2)
+
+aloc2 = r1.get_mesh_local_prefix().split('/')[0] + 'ff:fe00:fc11'
+
+r1.ping(aloc2)
+
+for node in nodes:
+    node.ping(aloc2)
+
+# -----------------------------------------------------------------------------------------------------------------------
+# Test finished
+
+cli.Node.finalize_all_nodes()
+
+print('\'{}\' passed.'.format(test_name))

tests/toranj/start.sh

@@ -194,6 +194,7 @@ if [ "$TORANJ_CLI" = 1 ]; then
     run cli/test-027-slaac-address.py
     run cli/test-028-border-agent-ephemeral-key.py
     run cli/test-029-pending-dataset-key-change.py
+    run cli/test-030-anycast-forwarding.py
     run cli/test-400-srp-client-server.py
     run cli/test-401-srp-server-address-cache-snoop.py
     run cli/test-500-two-brs-two-networks.py