Update interfaces to allow more customizability

* pass clientId in Authentication
* pass username, password (if set in broker constructor), payload in Authorization
* pass clientId and username in PacketInterceptor

Readme.md

@@ -41,7 +41,7 @@ repositories {
     maven { url "https://jitpack.io" }
 }
 dependencies {
-    implementation 'com.github.davidepianca98.KMQTT:KMQTT-jvm:0.2.7'
+    implementation 'com.github.davidepianca98.KMQTT:kmqtt-jvm:0.2.7'
 }
 ```
 
@@ -92,7 +92,7 @@ fun main() {
 ```kotlin
 fun main() {
     val broker = Broker(authentication = object : Authentication {
-        override fun authenticate(username: String?, password: UByteArray?): Boolean {
+        override fun authenticate(clientId: String, username: String?, password: UByteArray?): Boolean {
             // TODO Implement your authentication method    
             return username == "user" && password?.toByteArray()?.decodeToString() == "pass"
         }
@@ -101,11 +101,33 @@ fun main() {
 }
 ```
 
+#### Authorization code example
+
+```kotlin
+fun main() {
+    val broker = Broker(authorization = object : Authorization {
+        override fun authorize(
+            clientId: String,
+            username: String?,
+            password: UByteArray?, // != null only if savePassword set to true in the broker constructor
+            topicName: String,
+            isSubscription: Boolean,
+            payload: UByteArray?
+        ): Boolean {
+            // TODO Implement your authorization method    
+            return topicName == "$clientId/topic"
+        }
+    })
+    broker.listen()
+}
+```
+
 #### Message interceptor code example
+
 ```kotlin
 fun main() {
     val broker = Broker(packetInterceptor = object : PacketInterceptor {
-        override fun packetReceived(packet: MQTTPacket) {
+        override fun packetReceived(clientId: String, username: String?, packet: MQTTPacket) {
             when(packet) {
                 is MQTTConnect -> println(packet.protocolName)
                 is MQTTPublish -> println(packet.topicName)
@@ -130,3 +152,12 @@ fun main() {
     broker.listen()
 }
 ```
+
+#### Other advanced functionality
+
+MQTT5 Enhanced Authentication: set the `enhancedAuthenticationProviders` Broker constructor parameter, implementing the
+provider interface `EnhancedAuthenticationProvider`.
+
+Session persistence: set the `persistence` Broker constructor parameter, implementing `Persistence` interface.
+
+Bytes metrics: set the `bytesMetrics` Broker constructor parameter, implementing `BytesMetrics` interface.  

src/commonMain/kotlin/mqtt/broker/Broker.kt

@@ -24,6 +24,7 @@ class Broker(
     val authentication: Authentication? = null,
     val enhancedAuthenticationProviders: Map<String, EnhancedAuthenticationProvider> = mapOf(),
     val authorization: Authorization? = null,
+    val savePassword: Boolean = false,
     val maximumSessionExpiryInterval: UInt = 0xFFFFFFFFu,
     val receiveMaximum: UShort? = 1024u,
     val maximumQos: Qos? = null,

src/commonMain/kotlin/mqtt/broker/ClientConnection.kt

@@ -26,6 +26,8 @@ class ClientConnection(
     }
 
     private var clientId: String? = null
+    private var username: String? = null
+    private var password: UByteArray? = null
     private var session: Session? = null
 
     // Client connection state
@@ -169,7 +171,7 @@ class ClientConnection(
                 else -> throw MQTTException(ReasonCode.PROTOCOL_ERROR)
             }
         }
-        broker.packetInterceptor?.packetReceived(packet)
+        broker.packetInterceptor?.packetReceived(clientId!!, username, packet)
     }
 
     /**
@@ -218,7 +220,7 @@ class ClientConnection(
     private fun handleAuthentication(packet: MQTTConnect) {
         if (broker.authentication != null) {
             if (packet.userName != null || packet.password != null) {
-                if (!broker.authentication.authenticate(packet.userName, packet.password)) {
+                if (!broker.authentication.authenticate(clientId!!, packet.userName, packet.password)) {
                     throw MQTTException(ReasonCode.NOT_AUTHORIZED)
                 }
             } else {
@@ -272,16 +274,20 @@ class ClientConnection(
 
     private fun handleConnect(packet: MQTTConnect) {
         connectPacket = packet
-        handleAuthentication(packet)
 
-        val clientId = if (packet.clientID.isEmpty()) {
+        val clientId = packet.clientID.ifEmpty {
             if (packet is MQTT4Connect && !packet.connectFlags.cleanStart) {
                 writePacket(MQTT4Connack(ConnectAcknowledgeFlags(false), ConnectReturnCode.IDENTIFIER_REJECTED))
                 return
             }
             generateClientId()
-        } else packet.clientID
+        }
         this.clientId = clientId
+        this.username = packet.userName
+        if (broker.savePassword) {
+            this.password = packet.password
+        }
+        handleAuthentication(packet)
 
         if (packet is MQTT5Connect && packet.properties.authenticationMethod != null) {
             packet.properties.authenticationMethod?.let { authenticationMethod ->
@@ -463,8 +469,15 @@ class ClientConnection(
         packetsReceivedBeforeConnack.clear()
     }
 
-    private fun checkAuthorization(topicName: String, isSubscription: Boolean): Boolean {
-        return broker.authorization?.authorize(clientId!!, topicName, isSubscription) != false
+    private fun checkAuthorization(topicName: String, isSubscription: Boolean, payload: UByteArray?): Boolean {
+        return broker.authorization?.authorize(
+            clientId!!,
+            username,
+            password,
+            topicName,
+            isSubscription,
+            payload
+        ) != false
     }
 
     private fun handlePublish(packet: MQTTPublish) {
@@ -476,7 +489,7 @@ class ClientConnection(
         // Handle topic alias
         val topic = getTopicOrAlias(packet)
 
-        if (!checkAuthorization(topic, false))
+        if (!checkAuthorization(topic, false, packet.payload))
             throw MQTTException(ReasonCode.NOT_AUTHORIZED)
 
         if (packet.qos > broker.maximumQos ?: Qos.EXACTLY_ONCE) {
@@ -687,7 +700,7 @@ class ClientConnection(
 
         val retainedMessagesList = mutableListOf<MQTTPublish>()
         val reasonCodes = packet.subscriptions.map { subscription ->
-            if (!checkAuthorization(subscription.topicFilter, true))
+            if (!checkAuthorization(subscription.topicFilter, true, null))
                 return@map ReasonCode.NOT_AUTHORIZED
 
             if (!subscription.matchTopicFilter.isValidTopic())

src/commonMain/kotlin/mqtt/broker/interfaces/Authentication.kt

@@ -2,5 +2,11 @@ package mqtt.broker.interfaces
 
 interface Authentication {
 
-    fun authenticate(username: String?, password: UByteArray?): Boolean
+    /**
+     * Checks if the client is allowed to connect to the broker
+     * @param clientId the MQTT clientId assigned to the client
+     * @param username the MQTT username provided in the CONNECT packet, if present, null otherwise
+     * @param password the MQTT password provided in the CONNECT packet, if present, null otherwise
+     */
+    fun authenticate(clientId: String, username: String?, password: UByteArray?): Boolean
 }

src/commonMain/kotlin/mqtt/broker/interfaces/Authorization.kt

@@ -2,5 +2,22 @@ package mqtt.broker.interfaces
 
 interface Authorization {
 
-    fun authorize(clientId: String, topicName: String, isSubscription: Boolean): Boolean
+    /**
+     * Checks if the client is allowed to do the specified operation
+     * @param clientId the MQTT clientId assigned to the client
+     * @param username the MQTT username provided in the CONNECT packet, if present, null otherwise
+     * @param password the MQTT password provided in the CONNECT packet, if present and broker parameter savePassword=true, null otherwise
+     * @param topicName the topic of the PUBLISH or SUBSCRIBE packet
+     * @param isSubscription true if the packet received is a SUBSCRIBE, false if it's a PUBLISH
+     * @param payload the content of the PUBLISH message, present only if isSubscription is false
+     * @return true if the client is allowed to publish or subscribe, false otherwise
+     */
+    fun authorize(
+        clientId: String,
+        username: String?,
+        password: UByteArray?,
+        topicName: String,
+        isSubscription: Boolean,
+        payload: UByteArray?
+    ): Boolean
 }

src/commonMain/kotlin/mqtt/broker/interfaces/BytesMetrics.kt

@@ -2,7 +2,17 @@ package mqtt.broker.interfaces
 
 interface BytesMetrics {
 
+    /**
+     * Called when a client receives a packet
+     * @param clientId the clientId of the client that received the packet
+     * @param bytesCount the size of the received packet
+     */
     fun received(clientId: String, bytesCount: Long)
 
+    /**
+     * Called when a client sends a packet
+     * @param clientId the clientId of the client that sent the packet
+     * @param bytesCount the size of the sent packet
+     */
     fun sent(clientId: String, bytesCount: Long)
 }

src/commonMain/kotlin/mqtt/broker/interfaces/EnhancedAuthentication.kt

@@ -12,7 +12,7 @@ interface EnhancedAuthenticationProvider {
      * Gets called upon reception of a CONNECT packet with the Authentication Method property set or upon reception
      * of an AUTH packet
      * @param clientId the requested or assigned Client ID if none is given by the client
-     * @param authenticationData the Authentication Data received if present in the received packet
+     * @param authenticationData the Authentication Data received, if present, in the received packet
      * @param result function to call to continue the authentication or to set it as complete
      */
     fun authReceived(

src/commonMain/kotlin/mqtt/broker/interfaces/PacketInterceptor.kt

@@ -4,5 +4,11 @@ import mqtt.packets.MQTTPacket
 
 interface PacketInterceptor {
 
-    fun packetReceived(packet: MQTTPacket)
+    /**
+     * Called when a packet is received from a client
+     * @param clientId the clientId assigned to the MQTT client that sent the packet
+     * @param username the MQTT username provided in the CONNECT packet, if present, null otherwise
+     * @param packet the MQTT packet sent by the client
+     */
+    fun packetReceived(clientId: String, username: String?, packet: MQTTPacket)
 }

src/jvmTest/kotlin/RunLocal.kt

@@ -3,7 +3,14 @@ import mqtt.broker.interfaces.Authorization
 
 fun main() {
     Broker(serverKeepAlive = 60, authorization = object : Authorization {
-        override fun authorize(clientId: String, topicName: String, isSubscription: Boolean): Boolean {
+        override fun authorize(
+            clientId: String,
+            username: String?,
+            password: UByteArray?,
+            topicName: String,
+            isSubscription: Boolean,
+            payload: UByteArray?
+        ): Boolean {
             return topicName != "test/nosubscribe"
         }
     }).listen()

src/jvmTest/kotlin/integration/AuthenticationTest.kt

@@ -38,7 +38,7 @@ class AuthenticationTest {
     @Test
     fun testSimpleAuthentication() {
         val broker = Broker(authentication = object : Authentication {
-            override fun authenticate(username: String?, password: UByteArray?): Boolean {
+            override fun authenticate(clientId: String, username: String?, password: UByteArray?): Boolean {
                 return username == "user" && password?.toByteArray()?.decodeToString() == "pass"
             }
         })
@@ -58,7 +58,7 @@ class AuthenticationTest {
     @Test(expected = Mqtt5ConnAckException::class)
     fun testSimpleAuthenticationFailure() {
         val broker = Broker(authentication = object : Authentication {
-            override fun authenticate(username: String?, password: UByteArray?): Boolean {
+            override fun authenticate(clientId: String, username: String?, password: UByteArray?): Boolean {
                 return username == "user" && password?.toByteArray()?.decodeToString() == "pass"
             }
         })