[mdns] add native mDNS support in OT (#9797)

This commit introduces native mDNS support within the OpenThread
stack, implementing RFC 6762 compliant registration of hosts,
services, and keys. It supports the following functionalities:

- Sending probes to claim names.
- Sending announcements on initial registration and changes.
- Sending "goodbye" announcements when unregistered or upon record
  removal.
- Negative responses (NSEC).
- Support for service sub-types and their addition/removal.
- Support for `_services._dns-sd._udp` queries (all service types).
- Responding to queries (including "QU" questions).
- Delay mechanism when responding to multi-question query messages,
  ensuring unique answers.
- Providing extra records in the Additional Data section if not
  already in the Answer section (e.g., on a PTR query, include SRV
  and host AAAA addresses).
- Implementing Known-Answer Suppression.
- Supporting multi-packet queries with known answers in follow-up
  messages.
- Rate-limiting record multicasts (once per second).
- Rate-limiting probe responses (once per 250ms).
- Detecting conflicts after probes.
- Limiting the size of emitted responses or probes, breaking into
  multiple messages if necessary.
- Detecting self originating messages (sent by mDNS module).
- Support for service browser.
- Support for service resolvers (SRV and TXT records) and IPv4/IPv6
  address resolvers for hostnames.
- Introduces smart cache management:
  - Passively caches service records for active browsers.
  - Passively caches address records for active service resolvers.
- Enables multiple simultaneous browsers/resolvers for the same
  service/host.

This commit introduces public `otMdns` OpenThread APIs and related CLI
commands for the mDNS module.

For platform abstraction, `otPlatMdns` APIs are defined in
`mdns_socket.h` (e.g., to send or receive mDNS messages):

- An implementation of the platform APIs is provided for posix.
- Also under the simulation platform, a simplified implementation of the
  `otPlatMdns` APIs is provided (intended for testing).

This commit also adds a detailed `test_mdns` unit test, validating
various functionalities and covering potential edge cases.

doc/ot_api_doc.h

@@ -58,6 +58,7 @@
  * @defgroup api-dnssd-server         DNS-SD Server
  * @defgroup api-icmp6                ICMPv6
  * @defgroup api-ip6                  IPv6
+ * @defgroup api-mdns                 Multicast DNS
  * @defgroup api-nat64                NAT64
  * @defgroup api-srp                  SRP
  * @defgroup api-ping-sender          Ping Sender
@@ -181,6 +182,7 @@
  * @defgroup plat-memory              Memory
  * @defgroup plat-messagepool         Message Pool
  * @defgroup plat-misc                Miscellaneous
+ * @defgroup plat-mdns                Multicast DNS
  * @defgroup plat-multipan            Multipan
  * @defgroup plat-otns                Network Simulator
  * @defgroup plat-radio               Radio

doc/ot_config_doc.h

@@ -69,6 +69,7 @@
  * @defgroup config-mesh-forwarder           Mesh Forwarder
  * @defgroup config-misc                     Miscellaneous Constants
  * @defgroup config-mle                      MLE Service
+ * @defgroup config-mdns                     Multicast DNS
  * @defgroup config-nat64                    NAT64
  * @defgroup config-netdata-publisher        Network Data Publisher
  * @defgroup config-network-diagnostic       Network Diagnostics

etc/cmake/options.cmake

@@ -215,6 +215,7 @@ ot_option(OT_LINK_METRICS_SUBJECT OPENTHREAD_CONFIG_MLE_LINK_METRICS_SUBJECT_ENA
 ot_option(OT_LINK_RAW OPENTHREAD_CONFIG_LINK_RAW_ENABLE "link raw service")
 ot_option(OT_LOG_LEVEL_DYNAMIC OPENTHREAD_CONFIG_LOG_LEVEL_DYNAMIC_ENABLE "dynamic log level control")
 ot_option(OT_MAC_FILTER OPENTHREAD_CONFIG_MAC_FILTER_ENABLE "mac filter")
+ot_option(OT_MDNS OPENTHREAD_CONFIG_MULTICAST_DNS_ENABLE "multicast DNS (mDNS)")
 ot_option(OT_MESH_DIAG OPENTHREAD_CONFIG_MESH_DIAG_ENABLE "mesh diag")
 ot_option(OT_MESSAGE_USE_HEAP OPENTHREAD_CONFIG_MESSAGE_USE_HEAP_ENABLE "heap allocator for message buffers")
 ot_option(OT_MLE_LONG_ROUTES OPENTHREAD_CONFIG_MLE_LONG_ROUTES_ENABLE "MLE long routes extension (experimental)")

examples/config/ot-core-config-check-size-br.h

@@ -79,6 +79,7 @@
 #define OPENTHREAD_CONFIG_MLE_LINK_METRICS_INITIATOR_ENABLE 1
 #define OPENTHREAD_CONFIG_MLE_LINK_METRICS_SUBJECT_ENABLE 1
 #define OPENTHREAD_CONFIG_MLR_ENABLE 1
+#define OPENTHREAD_CONFIG_MULTICAST_DNS_ENABLE 1
 #define OPENTHREAD_CONFIG_MULTIPLE_INSTANCE_ENABLE 0
 #define OPENTHREAD_CONFIG_NAT64_BORDER_ROUTING_ENABLE 1
 #define OPENTHREAD_CONFIG_NAT64_TRANSLATOR_ENABLE 1
@@ -99,5 +100,6 @@
 #define OPENTHREAD_CONFIG_DNS_DSO_MOCK_PLAT_APIS_ENABLE 1
 #define OPENTHREAD_CONFIG_BORDER_ROUTING_MOCK_PLAT_APIS_ENABLE 1
 #define OPENTHREAD_CONFIG_DNS_UPSTREAM_QUERY_MOCK_PLAT_APIS_ENABLE 1
+#define OPENTHREAD_CONFIG_MULTICAST_DNS_MOCK_PLAT_APIS_ENABLE 1
 
 #endif // OT_CORE_CONFIG_CHECK_SIZE_BR_H_

examples/platforms/simulation/CMakeLists.txt

@@ -69,6 +69,7 @@ add_library(openthread-simulation
     flash.c
     infra_if.c
     logging.c
+    mdns_socket.c
     misc.c
     multipan.c
     radio.c