[border-agent] manage mDNS MeshCoP service registrations (openthread#11455)

This commit updates `BorderAgent` modules to directly manage the
registration of mDNS MeshCoP services. Previously, this was the
responsibility of the platform or higher-level code. This behavior is
enabled using `OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE`
configuration option.

When enabled, the `BorderAgent` module itself will register the
`_meshcop._udp` service name with properly formatted TXT data. As the
state changes, the service registration is updated accordingly.

If the ephemeral key feature is enabled and used, the `BorderAgent`
will also manage the registration of the `_meshcop-e._udp` service.

The implementation allows the service instance name to be configured
in different ways. The Thread specification recommends using a
user-friendly name, such as "<VendorName> <ProductName>". The
name can be set using a newly added configuration option, or
alternatively, using a newly added public API for projects where the
name needs to be set at run-time after device initialization.

This commit also updates `test_border_agent`, validating all the
newly added behaviors related to MeshCoP service registrations.

Author: abtink

etc/cmake/options.cmake

@@ -176,6 +176,7 @@ ot_option(OT_BLE_TCAT OPENTHREAD_CONFIG_BLE_TCAT_ENABLE "Ble based thread commis
 ot_option(OT_BORDER_AGENT OPENTHREAD_CONFIG_BORDER_AGENT_ENABLE "border agent")
 ot_option(OT_BORDER_AGENT_EPSKC OPENTHREAD_CONFIG_BORDER_AGENT_EPHEMERAL_KEY_ENABLE "border agent ephemeral PSKc")
 ot_option(OT_BORDER_AGENT_ID OPENTHREAD_CONFIG_BORDER_AGENT_ID_ENABLE "create and save border agent ID")
+ot_option(OT_BORDER_AGENT_MESHCOP_SERVICE OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE "border agent meshcop service")
 ot_option(OT_BORDER_ROUTER OPENTHREAD_CONFIG_BORDER_ROUTER_ENABLE "border router")
 ot_option(OT_BORDER_ROUTING OPENTHREAD_CONFIG_BORDER_ROUTING_ENABLE "border routing")
 ot_option(OT_BORDER_ROUTING_DHCP6_PD OPENTHREAD_CONFIG_BORDER_ROUTING_DHCP6_PD_ENABLE "dhcpv6 pd support in border routing")
@@ -332,6 +333,7 @@ ot_multi_option(OT_LOG_OUTPUT OT_LOG_OUTPUT_VALUES OPENTHREAD_CONFIG_LOG_OUTPUT
 ot_string_option(OT_VENDOR_NAME OPENTHREAD_CONFIG_NET_DIAG_VENDOR_NAME "set the vendor name config")
 ot_string_option(OT_VENDOR_MODEL OPENTHREAD_CONFIG_NET_DIAG_VENDOR_MODEL "set the vendor model config")
 ot_string_option(OT_VENDOR_SW_VERSION OPENTHREAD_CONFIG_NET_DIAG_VENDOR_SW_VERSION "set the vendor sw version config")
+ot_string_option(OT_BORDER_AGENT_SERVICE_NAME OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME "set the border agent service base name")
 
 set(OT_POWER_SUPPLY_VALUES "BATTERY" "EXTERNAL" "EXTERNAL_STABLE" "EXTERNAL_UNSTABLE")
 ot_multi_option(OT_POWER_SUPPLY OT_POWER_SUPPLY_VALUES OPENTHREAD_CONFIG_DEVICE_POWER_SUPPLY OT_POWER_SUPPLY_ "set the device power supply config")

include/openthread/border_agent.h

@@ -35,6 +35,7 @@
 #ifndef OPENTHREAD_BORDER_AGENT_H_
 #define OPENTHREAD_BORDER_AGENT_H_
 
+#include <openthread/dns.h>
 #include <openthread/instance.h>
 #include <openthread/ip6.h>
 
@@ -242,6 +243,41 @@ void otBorderAgentSetMeshCoPServiceChangedCallback(otInstance
  */
 otError otBorderAgentGetMeshCoPServiceTxtData(otInstance *aInstance, otBorderAgentMeshCoPServiceTxtData *aTxtData);
 
+/**
+ * Maximum string length of base name used in `otBorderAgentSetMeshCoPServiceBaseName()`.
+ *
+ * The full DNS label is constructed by appending the Extended Address of the device (as 16-character hex digits) to
+ * the given base name.
+ */
+#define OT_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME_MAX_LENGTH (OT_DNS_MAX_LABEL_SIZE - 17)
+
+/**
+ * Sets the base name to construct the service instance name used when advertising the mDNS `_meshcop._udp` service by
+ * the Border Agent.
+ *
+ * Requires the `OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE` feature.
+ *
+ * The name can also be configured using the `OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME` configuration
+ * option (which is the recommended way to specify this name). This API is provided for projects where the name needs
+ * to be set after device initialization and at run-time.
+ *
+ * Per the Thread specification, the service instance should be a user-friendly name identifying the device model or
+ * product. A recommended format is "<VendorName> <ProductName>".
+ *
+ * To construct the full name and ensure name uniqueness, the OpenThread Border Agent module will append the Extended
+ * Address of the device (as 16-character hex digits) to the given base name.
+ *
+ * Note that the same name will be used for the ephemeral key service `_meshcop-e._udp` when the ephemeral key feature
+ * is enabled and used.
+ *
+ * @param[in] aInstance  The OpenThread instance.
+ * @param[in] aBaseName  The base name to use (MUST not be NULL).
+ *
+ * @retval OT_ERROR_NONE          The name was set successfully.
+ * @retval OT_ERROR_INVALID_ARGS  The name is too long or invalid.
+ */
+otError otBorderAgentSetMeshCoPServiceBaseName(otInstance *aInstance, const char *aBaseName);
+
 /**
  * Gets the randomly generated Border Agent ID.
  *

include/openthread/instance.h

@@ -52,7 +52,7 @@ extern "C" {
  *
  * @note This number versions both OpenThread platform and user APIs.
  */
-#define OPENTHREAD_API_VERSION (505)
+#define OPENTHREAD_API_VERSION (506)
 
 /**
  * @addtogroup api-instance

src/cli/README.md

@@ -410,6 +410,21 @@ Active
 Done
 ```
 
+### ba servicebasename \<name\>
+
+Sets the base name to construct the service instance name used when advertising the mDNS `_meshcop._udp` service by the Border Agent.
+
+Requires the `OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE` feature.
+
+The name can also be configured using the `OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME` configuration option (which is the recommended way to specify this name). This CLI command (and its corresponding API) is provided for projects where the name needs to be set after device initialization and at run-time.
+
+Per the Thread specification, the service instance should be a user-friendly name identifying the device model or product. A recommended format is "<VendorName> <ProductName>". To construct the full name and ensure name uniqueness, the OpenThread Border Agent module will append the Extended Address of the device (as 16-character hex digits) to the given base name. Note that the same name will be used for the ephemeral key service `_meshcop-e._udp` when the ephemeral key feature is enabled and used.
+
+```bash
+ba servicebasename OpenThreadBorderAgent
+Done
+```
+
 ### ba sessions
 
 Prints the list of Border Agent's sessions. Information per session:

src/cli/cli.cpp

@@ -502,6 +502,22 @@ template <> otError Interpreter::Process<Cmd("ba")>(Arg aArgs[])
             OutputLine("%s", otBorderAgentIsActive(GetInstancePtr()) ? "Active" : "Inactive");
         }
     }
+#if OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE
+    /**
+     * @cli ba servicebasename
+     * @code
+     * ba servicebasename OpenThreadBorderAgent
+     * Done
+     * @endcode
+     * @par api_copy
+     * #otBorderAgentSetMeshCoPServiceBaseName
+     */
+    else if (aArgs[0] == "servicebasename")
+    {
+        VerifyOrExit(!aArgs[1].IsEmpty() && aArgs[2].IsEmpty(), error = OT_ERROR_INVALID_ARGS);
+        error = otBorderAgentSetMeshCoPServiceBaseName(GetInstancePtr(), aArgs[1].GetCString());
+    }
+#endif
     /**
      * @cli ba sessions
      * @code

src/core/api/border_agent_api.cpp

@@ -57,6 +57,15 @@ bool otBorderAgentIsActive(otInstance *aInstance)
     return AsCoreType(aInstance).Get<MeshCoP::BorderAgent>().IsRunning();
 }
 
+#if OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE
+otError otBorderAgentSetMeshCoPServiceBaseName(otInstance *aInstance, const char *aBaseName)
+{
+    AssertPointerIsNotNull(aBaseName);
+
+    return AsCoreType(aInstance).Get<MeshCoP::BorderAgent>().SetServiceBaseName(aBaseName);
+}
+#endif
+
 #if OPENTHREAD_CONFIG_BORDER_AGENT_ID_ENABLE
 otError otBorderAgentGetId(otInstance *aInstance, otBorderAgentId *aId)
 {

src/core/config/border_agent.h

@@ -89,6 +89,38 @@
     OPENTHREAD_CONFIG_BORDER_AGENT_EPHEMERAL_KEY_ENABLE
 #endif
 
+/**
+ * @def OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE
+ *
+ * Define to 1 to enable Border Agent to manage registering/updating of the mDNS MeshCoP service(s) on the
+ * infrastructure link
+ *
+ * This includes the ephemeral key service when the `OPENTHREAD_CONFIG_BORDER_AGENT_EPHEMERAL_KEY_ENABLE` is enabled.
+ */
+#ifndef OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE
+#define OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE \
+    (OPENTHREAD_CONFIG_PLATFORM_DNSSD_ENABLE || OPENTHREAD_CONFIG_MULTICAST_DNS_ENABLE)
+#endif
+
+/**
+ * @def OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME
+ *
+ * Specifies the base name to construct the service instance name used when advertising the mDNS `_meshcop._udp`
+ * service by the Border Agent.
+ *
+ * Applicable when the `OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_ENABLE` feature is enabled.
+ *
+ * The name can also be configured using the `otBorderAgentSetMeshCoPServiceBaseName()` API at run-time.
+ *
+ * Per the Thread specification, the service instance should be a user-friendly name identifying the device model or
+ * product. A recommended format is "<VendorName> <ProductName>".
+ *
+ * The name MUST have a length less than or equal to `OT_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME_MAX_LENGTH` (47 chars).
+ */
+#ifndef OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME
+#define OPENTHREAD_CONFIG_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME "OpenThread BR (unspecified vendor) "
+#endif
+
 /**
  * @}
  */