[platform] implement platform dnssd apis (#2664)

This commit adds `DnssdPlatform` module to implement OT platform DNSSD
APIs.

In this commit, `DnssdPlatform` is added but not used yet. It will be
enabled and used later when the native Border Agent MeshCoP Service
publishing is ready.

In this commit, these platform DNSSD APIs are implemented while the
rest of them has an empty implementation and will be implemented when
necessary:
* otPlatDnssdGetState
* otPlatDnssdRegisterService
* otPlatDnssdUnregisterService
* otPlatDnssdRegisterHost
* otPlatDnssdUnregisterHost
* otPlatDnssdRegisterKey
* otPlatDnssdUnregisterKey

src/host/posix/CMakeLists.txt

@@ -27,6 +27,7 @@
 #
 
 add_library(otbr-posix
+    dnssd.cpp
     infra_if.hpp
     infra_if.cpp
     netif.cpp

src/host/posix/dnssd.cpp

@@ -0,0 +1,325 @@
+/*
+ *    Copyright (c) 2025, 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.
+ */
+
+/**
+ * @file
+ *   This file includes implementation of OpenThread DNS-SD platform APIs on the posix platform.
+ */
+
+#define OTBR_LOG_TAG "DNSSD"
+
+#include "host/posix/dnssd.hpp"
+
+#include <string>
+
+#include <openthread/platform/dnssd.h>
+
+#include "common/code_utils.hpp"
+#include "common/logging.hpp"
+#include "common/types.hpp"
+
+static otbr::DnssdPlatform::RegisterCallback MakeRegisterCallback(otInstance                 *aInstance,
+                                                                  otPlatDnssdRegisterCallback aCallback)
+{
+    return [aInstance, aCallback](otPlatDnssdRequestId aRequestId, otError aError) {
+        aCallback(aInstance, aRequestId, aError);
+    };
+}
+
+extern "C" otPlatDnssdState otPlatDnssdGetState(otInstance *aInstance)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    return otbr::DnssdPlatform::Get().GetState();
+}
+
+extern "C" void otPlatDnssdRegisterService(otInstance                 *aInstance,
+                                           const otPlatDnssdService   *aService,
+                                           otPlatDnssdRequestId        aRequestId,
+                                           otPlatDnssdRegisterCallback aCallback)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    otbr::DnssdPlatform::Get().RegisterService(*aService, aRequestId, MakeRegisterCallback(aInstance, aCallback));
+}
+
+extern "C" void otPlatDnssdUnregisterService(otInstance                 *aInstance,
+                                             const otPlatDnssdService   *aService,
+                                             otPlatDnssdRequestId        aRequestId,
+                                             otPlatDnssdRegisterCallback aCallback)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    otbr::DnssdPlatform::Get().UnregisterService(*aService, aRequestId, MakeRegisterCallback(aInstance, aCallback));
+}
+
+extern "C" void otPlatDnssdRegisterHost(otInstance                 *aInstance,
+                                        const otPlatDnssdHost      *aHost,
+                                        otPlatDnssdRequestId        aRequestId,
+                                        otPlatDnssdRegisterCallback aCallback)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    otbr::DnssdPlatform::Get().RegisterHost(*aHost, aRequestId, MakeRegisterCallback(aInstance, aCallback));
+}
+
+extern "C" void otPlatDnssdUnregisterHost(otInstance                 *aInstance,
+                                          const otPlatDnssdHost      *aHost,
+                                          otPlatDnssdRequestId        aRequestId,
+                                          otPlatDnssdRegisterCallback aCallback)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    otbr::DnssdPlatform::Get().UnregisterHost(*aHost, aRequestId, MakeRegisterCallback(aInstance, aCallback));
+}
+
+extern "C" void otPlatDnssdRegisterKey(otInstance                 *aInstance,
+                                       const otPlatDnssdKey       *aKey,
+                                       otPlatDnssdRequestId        aRequestId,
+                                       otPlatDnssdRegisterCallback aCallback)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    otbr::DnssdPlatform::Get().RegisterKey(*aKey, aRequestId, MakeRegisterCallback(aInstance, aCallback));
+}
+
+extern "C" void otPlatDnssdUnregisterKey(otInstance                 *aInstance,
+                                         const otPlatDnssdKey       *aKey,
+                                         otPlatDnssdRequestId        aRequestId,
+                                         otPlatDnssdRegisterCallback aCallback)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+
+    otbr::DnssdPlatform::Get().UnregisterKey(*aKey, aRequestId, MakeRegisterCallback(aInstance, aCallback));
+}
+
+extern "C" void otPlatDnssdStartBrowser(otInstance *aInstance, const otPlatDnssdBrowser *aBrowser)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aBrowser);
+}
+
+extern "C" void otPlatDnssdStopBrowser(otInstance *aInstance, const otPlatDnssdBrowser *aBrowser)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aBrowser);
+}
+
+extern "C" void otPlatDnssdStartSrvResolver(otInstance *aInstance, const otPlatDnssdSrvResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+extern "C" void otPlatDnssdStopSrvResolver(otInstance *aInstance, const otPlatDnssdSrvResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+extern "C" void otPlatDnssdStartTxtResolver(otInstance *aInstance, const otPlatDnssdTxtResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+extern "C" void otPlatDnssdStopTxtResolver(otInstance *aInstance, const otPlatDnssdTxtResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+extern "C" void otPlatDnssdStartIp6AddressResolver(otInstance *aInstance, const otPlatDnssdAddressResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+extern "C" void otPlatDnssdStopIp6AddressResolver(otInstance *aInstance, const otPlatDnssdAddressResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+void otPlatDnssdStartIp4AddressResolver(otInstance *aInstance, const otPlatDnssdAddressResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+void otPlatDnssdStopIp4AddressResolver(otInstance *aInstance, const otPlatDnssdAddressResolver *aResolver)
+{
+    OTBR_UNUSED_VARIABLE(aInstance);
+    OTBR_UNUSED_VARIABLE(aResolver);
+}
+
+//----------------------------------------------------------------------------------------------------------------------
+
+namespace otbr {
+
+DnssdPlatform *DnssdPlatform::sDnssdPlatform = nullptr;
+
+DnssdPlatform::DnssdPlatform(Mdns::Publisher &aPublisher)
+    : mPublisher(aPublisher)
+    , mState(kStateStopped)
+    , mRunning(false)
+    , mPublisherState(Mdns::Publisher::State::kIdle)
+{
+    sDnssdPlatform = this;
+}
+
+void DnssdPlatform::Start(void)
+{
+    if (!mRunning)
+    {
+        mRunning = true;
+        UpdateState();
+    }
+}
+
+void DnssdPlatform::Stop(void)
+{
+    if (mRunning)
+    {
+        mRunning = false;
+        UpdateState();
+    }
+}
+
+void DnssdPlatform::UpdateState(void)
+{
+    if (mRunning && (mPublisherState == Mdns::Publisher::State::kReady))
+    {
+        VerifyOrExit(mState != kStateReady);
+
+        mState = kStateReady;
+    }
+    else
+    {
+        VerifyOrExit(mState != kStateStopped);
+
+        mState = kStateStopped;
+    }
+
+    if (mStateChangeCallback)
+    {
+        mStateChangeCallback(mState);
+    }
+
+exit:
+    return;
+}
+
+Mdns::Publisher::ResultCallback DnssdPlatform::MakePublisherCallback(RequestId aRequestId, RegisterCallback aCallback)
+{
+    return [aRequestId, aCallback](otbrError aError) {
+        if (aCallback != nullptr)
+        {
+            aCallback(aRequestId, OtbrErrorToOtError(aError));
+        }
+    };
+}
+
+void DnssdPlatform::SetDnssdStateChangedCallback(DnssdStateChangeCallback aCallback)
+{
+    mStateChangeCallback = aCallback;
+}
+
+void DnssdPlatform::RegisterService(const Service &aService, RequestId aRequestId, RegisterCallback aCallback)
+{
+    Mdns::Publisher::SubTypeList subTypeList;
+    Mdns::Publisher::TxtData     txtData(aService.mTxtData, aService.mTxtData + aService.mTxtDataLength);
+
+    for (uint16_t index = 0; index < aService.mSubTypeLabelsLength; index++)
+    {
+        subTypeList.push_back(aService.mSubTypeLabels[index]);
+    }
+
+    mPublisher.PublishService(aService.mHostName, aService.mServiceInstance, aService.mServiceType, subTypeList,
+                              aService.mPort, txtData, MakePublisherCallback(aRequestId, aCallback));
+}
+
+void DnssdPlatform::UnregisterService(const Service &aService, RequestId aRequestId, RegisterCallback aCallback)
+{
+    mPublisher.UnpublishService(aService.mServiceInstance, aService.mServiceType,
+                                MakePublisherCallback(aRequestId, aCallback));
+}
+
+void DnssdPlatform::RegisterHost(const Host &aHost, RequestId aRequestId, RegisterCallback aCallback)
+{
+    Mdns::Publisher::AddressList addressList;
+
+    for (uint16_t index = 0; index < aHost.mAddressesLength; index++)
+    {
+        addressList.push_back(Ip6Address(aHost.mAddresses[index].mFields.m8));
+    }
+
+    mPublisher.PublishHost(aHost.mHostName, addressList, MakePublisherCallback(aRequestId, aCallback));
+}
+
+void DnssdPlatform::UnregisterHost(const Host &aHost, RequestId aRequestId, RegisterCallback aCallback)
+{
+    mPublisher.UnpublishHost(aHost.mHostName, MakePublisherCallback(aRequestId, aCallback));
+}
+
+std::string DnssdPlatform::KeyNameFor(const Key &aKey)
+{
+    std::string name(aKey.mName);
+
+    if (aKey.mServiceType != nullptr)
+    {
+        // TODO: current code would not work with service instance labels that include a '.'
+        name += ".";
+        name += aKey.mServiceType;
+    }
+
+    return name;
+}
+
+void DnssdPlatform::RegisterKey(const Key &aKey, RequestId aRequestId, RegisterCallback aCallback)
+{
+    Mdns::Publisher::KeyData keyData(aKey.mKeyData, aKey.mKeyData + aKey.mKeyDataLength);
+
+    mPublisher.PublishKey(KeyNameFor(aKey), keyData, MakePublisherCallback(aRequestId, aCallback));
+}
+
+void DnssdPlatform::UnregisterKey(const Key &aKey, RequestId aRequestId, RegisterCallback aCallback)
+{
+    mPublisher.UnpublishKey(KeyNameFor(aKey), MakePublisherCallback(aRequestId, aCallback));
+}
+
+void DnssdPlatform::HandleMdnsState(Mdns::Publisher::State aState)
+{
+    if (mPublisherState != aState)
+    {
+        mPublisherState = aState;
+        UpdateState();
+    }
+}
+
+} // namespace otbr