[srp-client] exclude non-preferred addresses in AutoAddress mode (#9642)

This commit updates the `AutoAddress` mode in `Srp::Client` to
exclude any deprecated (non-preferred) address when registering
host addresses.

It also updates `test_srp_auto_host_address` to validate the new
behavior.

include/openthread/instance.h

@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (378)
+#define OPENTHREAD_API_VERSION (379)
 
 /**
  * @addtogroup api-instance

include/openthread/srp_client.h

@@ -460,10 +460,10 @@ otError otSrpClientSetHostName(otInstance *aInstance, const char *aName);
 /**
  * Enables auto host address mode.
  *
- * When enabled host IPv6 addresses are automatically set by SRP client using all the unicast addresses on Thread netif
- * excluding all link-local and mesh-local addresses. If there is no valid address, then Mesh Local EID address is
- * added. The SRP client will automatically re-register when/if addresses on Thread netif are updated (new addresses
- * are added or existing addresses are removed).
+ * When enabled host IPv6 addresses are automatically set by SRP client using all the preferred unicast addresses on
+ * Thread netif excluding all link-local and mesh-local addresses. If there is no preferred address, then Mesh Local
+ * EID address is added. The SRP client will automatically re-register when/if addresses on Thread netif are updated
+ * (new addresses are added or existing addresses are removed or marked as non-preferred).
  *
  * The auto host address mode can be enabled before start or during operation of SRP client except when the host info
  * is being removed (client is busy handling a remove request from an call to `otSrpClientRemoveHostAndServices()` and

src/cli/README_SRP_CLIENT.md

@@ -187,7 +187,7 @@ fd00:0:0:0:0:0:0:beef
 Done
 ```
 
-Enable auto host address mode. When enabled client will automatically use all Thread netif unicast addresses excluding all link-local and mesh-local addresses. If there is no valid address, then Mesh Local EID address is added. SRP client will automatically re-register if/when addresses on Thread netif get changed (e.g., new address is added or existing address is removed).
+Enable auto host address mode. When enabled client will automatically use all preferred Thread netif unicast addresses excluding all link-local and mesh-local addresses. If there is no preferred address, then Mesh Local EID address is added. SRP client will automatically re-register if/when addresses on Thread netif get changed (e.g., new address is added or existing address is removed or marked as non-preferred).
 
 ```bash
 > srp client host address auto

src/cli/cli_srp_client.cpp

@@ -315,12 +315,12 @@ template <> otError SrpClient::Process<Cmd("host")>(Arg aArgs[])
          * @endcode
          * @cparam srp client host address [auto|@ca{address...}]
          *   * Use the `auto` parameter to enable auto host address mode.
-         *     When enabled, the client automatically uses all Thread `netif`
-         *     unicast addresses except for link-local and mesh-local
+         *     When enabled, the client automatically uses all preferred Thread
+         *     `netif` unicast addresses except for link-local and mesh-local
          *     addresses. If there is no valid address, the mesh local
          *     EID address gets added. The SRP client automatically
          *     re-registers if addresses on the Thread `netif` are
-         *     added or removed.
+         *     added or removed or marked as non-preferred.
          *   * Explicitly specify the list of host addresses, separating
          *     each address by a space. You can set this list while the client is
          *     running. This will also disable auto host address mode.

src/core/net/srp_client.cpp

@@ -1240,21 +1240,23 @@ Error Client::AppendHostDescriptionInstruction(Message &aMessage, Info &aInfo)
 
     if (mHostInfo.IsAutoAddressEnabled())
     {
-        // Append all addresses on Thread netif excluding link-local and
-        // mesh-local addresses. If no address is appended, we include
-        // the mesh local address.
+        // Append all preferred addresses on Thread netif excluding link-local
+        // and mesh-local addresses. If no address is appended, we include
+        // the mesh local EID.
 
         mAutoHostAddressAddedMeshLocal = true;
 
         for (const Ip6::Netif::UnicastAddress &unicastAddress : Get<ThreadNetif>().GetUnicastAddresses())
         {
-            if (unicastAddress.GetAddress().IsLinkLocal() ||
-                Get<Mle::Mle>().IsMeshLocalAddress(unicastAddress.GetAddress()))
+            const Ip6::Address &address = unicastAddress.GetAddress();
+
+            if (address.IsLinkLocal() || Get<Mle::Mle>().IsMeshLocalAddress(address) || !unicastAddress.mPreferred ||
+                !unicastAddress.mValid)
             {
                 continue;
             }
 
-            SuccessOrExit(error = AppendAaaaRecord(unicastAddress.GetAddress(), aMessage, aInfo));
+            SuccessOrExit(error = AppendAaaaRecord(address, aMessage, aInfo));
             mAutoHostAddressAddedMeshLocal = false;
         }
 

tests/scripts/thread-cert/node.py

@@ -1880,8 +1880,8 @@ class NodeImpl:
         self.send_command(cmd)
         self._expect_done()
 
-    def get_addrs(self):
-        self.send_command('ipaddr')
+    def get_addrs(self, verbose=False):
+        self.send_command('ipaddr' + (' -v' if verbose else ''))
 
         return self._expect_results(r'\S+(:\S*)+')
 

tests/scripts/thread-cert/test_srp_auto_host_address.py

@@ -155,6 +155,19 @@ class SrpAutoHostAddress(thread_cert.TestCase):
         self.assertEqual(len(slaac_addr), 1)
         self.check_registered_addresses(client, server)
 
+        #-------------------------------------------------------------------
+        # Add a non-preferred SLAAC on-mesh prefix and check that the
+        # set of registered addresses remains unchanged and that the
+        # non-preferred  address is not registered by SRP client.
+
+        client.add_prefix('fd00:a:b:c::/64', 'aos')
+        client.register_netdata()
+        self.simulator.go(5)
+
+        slaac_addr = [addr.strip() for addr in client.get_addrs() if addr.strip().startswith('fd00:a:b:c:')]
+        self.assertEqual(len(slaac_addr), 1)
+        self.check_registered_addresses(client, server)
+
         #-------------------------------------------------------------------
         # Remove the on-mesh prefix (which will trigger an address to be
         # removed) and check that the SRP client re-registered and updated
@@ -219,19 +232,21 @@ class SrpAutoHostAddress(thread_cert.TestCase):
         # Check the host addresses on server to match client.
 
         host_addresses = [addr.strip() for addr in server_host['addresses']]
-        client_addresses = [addr.strip() for addr in client.get_addrs()]
+
+        client_mleid = client.get_mleid()
+        client_addresses = [addr.split(' ')[0] for addr in client.get_addrs(verbose=True) if 'preferred:1' in addr]
+        client_addresses += [client_mleid]
 
         # All registered addresses must be in client list of addresses.
 
         for addr in host_addresses:
             self.assertIn(addr, client_addresses)
 
-        # All addresses on client excluding link-local and mesh-local
-        # addresses must be seen on server side. But if there was
-        # no address, then mesh-local address should be the only
+        # All preferred addresses on client excluding link-local and
+        # mesh-local addresses must be seen on server side. But if there
+        # was no address, then mesh-local address should be the only
         # one registered.
 
-        client_mleid = client.get_mleid()
         checked_address = False
 
         for addr in client_addresses: