Initiate topic alias to subscribers

I think it's correct, but mosquitto_sub doesn't seem to support it, so I can't test. Also some other stuff I happen to see.

Initiate topic alias to subscribers
I think it's correct, but mosquitto_sub doesn't seem to support it, so I can't test. Also some other stuff I happen to see.
Wiebe Cazemier
1 parent 9dab7a48
Showing 10 changed files with 68 additions and 20 deletions
client.cpp
client.h
mqtt5properties.cpp
mqtt5properties.h
mqttpacket.cpp
publishcopyfactory.cpp
publishcopyfactory.h
settings.h
types.cpp
types.h
@@ -208,7 +208,23 @@ int Client::writeMqttPacket(const MqttPacket &amp;packet)
 int Client::writeMqttPacketAndBlameThisClient(PublishCopyFactory &copyFactory, char max_qos, uint16_t packet_id)
 {
-    MqttPacket *p = copyFactory.getOptimumPacket(max_qos, this->protocolVersion);
+    const Settings *settings = ThreadGlobals::getSettings();
+    uint16_t topic_alias = 0;
+    bool skip_topic = false;
+
+    if (protocolVersion >= ProtocolVersion::Mqtt5 && settings->maxOutgoingTopicAliases > this->curOutgoingTopicAlias)
+    {
+        uint16_t &id = this->outgoingTopicAliases[copyFactory.getTopic()];
+
+        if (id > 0)
+            skip_topic = true;
+        else
+            id = ++this->curOutgoingTopicAlias;
+
+        topic_alias = id;
+    }
+
+    MqttPacket *p = copyFactory.getOptimumPacket(max_qos, this->protocolVersion, topic_alias, skip_topic);
     assert(p->getQos() <= max_qos);
@@ -84,6 +84,9 @@ class Client
     std::unordered_map<uint16_t, std::string> topicAliases;
+    uint16_t curOutgoingTopicAlias = 0;
+    std::unordered_map<std::string, uint16_t> outgoingTopicAliases;
+
     Logger *logger = Logger::getInstance();
     void setReadyForWriting(bool val);
@@ -125,6 +125,11 @@ void Mqtt5PropertyBuilder::writeCorrelationData(const std::string &amp;correlationDa
     writeStr(Mqtt5Properties::CorrelationData, correlationData);
 }
+void Mqtt5PropertyBuilder::writeTopicAlias(const uint16_t id)
+{
+    writeUint16(Mqtt5Properties::TopicAlias, id, clientSpecificBytes);
+}
+
 void Mqtt5PropertyBuilder::setNewUserProperties(const std::shared_ptr<std::vector<std::pair<std::string, std::string>>> &userProperties)
 {
     assert(!this->userProperties);
@@ -134,7 +139,7 @@ void Mqtt5PropertyBuilder::setNewUserProperties(const std::shared_ptr&lt;std::vecto
     this->userProperties = userProperties;
 }
-void Mqtt5PropertyBuilder::writeUint32(Mqtt5Properties prop, const uint32_t x, std::vector<char> &target)
+void Mqtt5PropertyBuilder::writeUint32(Mqtt5Properties prop, const uint32_t x, std::vector<char> &target) const
 {
     size_t pos = target.size();
     const size_t newSize = pos + 5;
@@ -154,16 +159,21 @@ void Mqtt5PropertyBuilder::writeUint32(Mqtt5Properties prop, const uint32_t x, s
 void Mqtt5PropertyBuilder::writeUint16(Mqtt5Properties prop, const uint16_t x)
 {
-    size_t pos = genericBytes.size();
+    writeUint16(prop, x, this->genericBytes);
+}
+
+void Mqtt5PropertyBuilder::writeUint16(Mqtt5Properties prop, const uint16_t x, std::vector<char> &target) const
+{
+    size_t pos = target.size();
     const size_t newSize = pos + 3;
-    genericBytes.resize(newSize);
+    target.resize(newSize);
     const uint8_t a = static_cast<uint8_t>(x >> 8);
     const uint8_t b = static_cast<uint8_t>(x);
-    genericBytes[pos++] = static_cast<uint8_t>(prop);
-    genericBytes[pos++] = a;
-    genericBytes[pos] = b;
+    target[pos++] = static_cast<uint8_t>(prop);
+    target[pos++] = a;
+    target[pos] = b;
 }
 void Mqtt5PropertyBuilder::writeUint8(Mqtt5Properties prop, const uint8_t x)
@@ -13,8 +13,9 @@ class Mqtt5PropertyBuilder
     std::shared_ptr<std::vector<std::pair<std::string, std::string>>> userProperties;
     VariableByteInt length;
-    void writeUint32(Mqtt5Properties prop, const uint32_t x, std::vector<char> &target);
+    void writeUint32(Mqtt5Properties prop, const uint32_t x, std::vector<char> &target) const;
     void writeUint16(Mqtt5Properties prop, const uint16_t x);
+    void writeUint16(Mqtt5Properties prop, const uint16_t x, std::vector<char> &target) const;
     void writeUint8(Mqtt5Properties prop, const uint8_t x);
     void writeStr(Mqtt5Properties prop, const std::string &str);
     void write2Str(Mqtt5Properties prop, const std::string &one, const std::string &two);
@@ -43,6 +44,7 @@ public:
     void writeResponseTopic(const std::string &str);
     void writeUserProperty(std::string &&key, std::string &&value);
     void writeCorrelationData(const std::string &correlationData);
+    void writeTopicAlias(const uint16_t id);
     void setNewUserProperties(const std::shared_ptr<std::vector<std::pair<std::string, std::string>>> &userProperties);
 };
@@ -108,7 +108,8 @@ MqttPacket::MqttPacket(const ProtocolVersion protocolVersion, const Publish &amp;_pu
     this->protocolVersion = protocolVersion;
-    this->publishData.topic = _publish.topic;
+    if (!_publish.skipTopic)
+        this->publishData.topic = _publish.topic;
     if (_publish.splitTopic)
         splitTopic(this->publishData.topic, this->publishData.subtopics);
@@ -133,7 +134,7 @@ MqttPacket::MqttPacket(const ProtocolVersion protocolVersion, const Publish &amp;_pu
     if (protocolVersion >= ProtocolVersion::Mqtt5)
     {
         // Step 1: make certain properties available as objects, because FlashMQ needs access to them for internal logic.
-        if (_publish.propertyBuilder)
+        if (_publish.propertyBuilder) // TODO: only do this when there are user properties. Otherwise we don't need it.
         {
             this->publishData.constructPropertyBuilder();
             this->publishData.propertyBuilder->setNewUserProperties(_publish.propertyBuilder->getUserProperties());
@@ -343,7 +344,7 @@ void MqttPacket::handleConnect()
         uint16_t max_qos_packets = settings.maxQosMsgPendingPerClient;
         uint32_t session_expire = settings.expireSessionsAfterSeconds > 0 ? settings.expireSessionsAfterSeconds : std::numeric_limits<uint32_t>::max();
         uint32_t max_packet_size = settings.maxPacketSize;
-        uint16_t max_topic_aliases = settings.maxTopicAliases;
+        uint16_t max_topic_aliases = settings.maxOutgoingTopicAliases;
         bool request_response_information = false;
         bool request_problem_information = false;
@@ -820,6 +821,7 @@ void MqttPacket::handlePublish()
             case Mqtt5Properties::MessageExpiryInterval:
                 publishData.createdAt = std::chrono::steady_clock::now();
                 publishData.expiresAfter = std::chrono::seconds(readFourBytesToUint32());
+                break;
             case Mqtt5Properties::TopicAlias:
             {
                 const uint16_t alias_id = readTwoBytesToUInt16();
@@ -17,15 +17,17 @@ PublishCopyFactory::PublishCopyFactory(Publish *publish) :
 }
-MqttPacket *PublishCopyFactory::getOptimumPacket(const char max_qos, const ProtocolVersion protocolVersion)
+MqttPacket *PublishCopyFactory::getOptimumPacket(const char max_qos, const ProtocolVersion protocolVersion, uint16_t topic_alias, bool skip_topic)
 {
     if (packet)
     {
-        if (packet->containsClientSpecificProperties())
+        if (protocolVersion >= ProtocolVersion::Mqtt5 && (packet->containsClientSpecificProperties() || topic_alias > 0))
         {
             Publish newPublish(packet->getPublishData());
             newPublish.splitTopic = false;
             newPublish.qos = max_qos;
+            newPublish.topicAlias = topic_alias;
+            newPublish.skipTopic = skip_topic;
             newPublish.setClientSpecificProperties();
             this->oneShotPacket = std::make_unique<MqttPacket>(protocolVersion, newPublish);
             return this->oneShotPacket.get();
@@ -29,7 +29,7 @@ public:
     PublishCopyFactory(const PublishCopyFactory &other) = delete;
     PublishCopyFactory(PublishCopyFactory &&other) = delete;
-    MqttPacket *getOptimumPacket(const char max_qos, const ProtocolVersion protocolVersion);
+    MqttPacket *getOptimumPacket(const char max_qos, const ProtocolVersion protocolVersion, uint16_t topic_alias, bool skip_topic);
     char getEffectiveQos(char max_qos) const;
     const std::string &getTopic() const;
     const std::vector<std::string> &getSubtopics();
@@ -42,7 +42,8 @@ public:
     bool authPluginSerializeAuthChecks = false;
     int clientInitialBufferSize = 1024; // Must be power of 2
     int maxPacketSize = 268435461; // 256 MB + 5
-    uint16_t maxTopicAliases = 65535;
+    uint16_t maxIncomingTopicAliases = 65535;
+    uint16_t maxOutgoingTopicAliases = 0; // TODO: setting, when I can confirm with clients that support it that it works.
 #ifdef TESTING
     bool logDebug = true;
 #else
@@ -117,7 +117,8 @@ PublishBase::PublishBase(const std::string &amp;topic, const std::string &amp;payload, c
 size_t PublishBase::getLengthWithoutFixedHeader() const
 {
-    int result = topic.length() + payload.length() + 2;
+    const int topicLength = this->skipTopic ? 0 : topic.length();
+    int result = topicLength + payload.length() + 2;
     if (qos)
         result += 2;
@@ -131,14 +132,23 @@ size_t PublishBase::getLengthWithoutFixedHeader() const
  */
 void PublishBase::setClientSpecificProperties()
 {
+    if (this->createdAt.time_since_epoch().count() && this->topicAlias == 0)
+        return;
+
     if (propertyBuilder)
         propertyBuilder->clearClientSpecificBytes();
+    else
+        propertyBuilder = std::make_shared<Mqtt5PropertyBuilder>();
-    auto now = std::chrono::steady_clock::now();
-    std::chrono::seconds newExpiresAfter = std::chrono::duration_cast<std::chrono::seconds>(now - createdAt);
-
-    if (newExpiresAfter.count() > 0)
+    if (createdAt.time_since_epoch().count() > 0)
+    {
+        auto now = std::chrono::steady_clock::now();
+        std::chrono::seconds newExpiresAfter = std::chrono::duration_cast<std::chrono::seconds>(now - createdAt);
         propertyBuilder->writeMessageExpiryInterval(newExpiresAfter.count());
+    }
+
+    if (topicAlias > 0)
+        propertyBuilder->writeTopicAlias(this->topicAlias);
 }
 void PublishBase::constructPropertyBuilder()
@@ -206,6 +206,8 @@ public:
     bool splitTopic = true;
     std::chrono::time_point<std::chrono::steady_clock> createdAt;
     std::chrono::seconds expiresAfter;
+    uint16_t topicAlias = 0;
+    bool skipTopic = false;
     std::shared_ptr<Mqtt5PropertyBuilder> propertyBuilder; // Only contains data for sending, not receiving
     PublishBase() = default;