Add message handler

Sming/Components/mdns/src/Server.cpp

@@ -93,17 +93,19 @@ void Server::onReceive(pbuf* buf, IpAddress remoteIP, uint16_t remotePort)
 		}
 	}
 
-	if(!messageCallback) {
+	if(handlers.isEmpty()) {
 		return;
 	}
 
 	Message message(remoteIP, remotePort, buf->payload, buf->len);
-	if(message.parse()) {
-		/*
-		 * TODO: Establish callback chain/queue to support multiple clients.
-		 * If a client returns false then don't pass it any further.
-		 */
-		messageCallback(message);
+	if(!message.parse()) {
+		return;
+	}
+
+	for(auto& handler : handlers) {
+		if(!handler.onMessage(message)) {
+			break;
+		}
 	}
 }
 

Sming/Components/mdns/src/include/Network/Mdns/Handler.h

@@ -0,0 +1,33 @@
+/****
+ * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
+ * Created 2015 by Skurydin Alexey
+ * http://github.com/SmingHub/Sming
+ * All files of the Sming Core are provided under the LGPL v3 license.
+ *
+ * Message.h
+ *
+ ****/
+
+#pragma once
+
+#include <Data/LinkedObjectList.h>
+#include "Message.h"
+
+namespace mDNS
+{
+/**
+ * @brief Virtual base class used for chaining message handlers
+ */
+class Handler : public LinkedObjectTemplate<Handler>
+{
+public:
+	using List = LinkedObjectListTemplate<Handler>;
+
+	/**
+	 * @brief Callback to be invoked for each received message
+	 * @retval bool Return true to pass message to other handlers, false to stop
+	 */
+	virtual bool onMessage(Message& message) = 0;
+};
+
+} // namespace mDNS

Sming/Components/mdns/src/include/Network/Mdns/Server.h

@@ -19,6 +19,7 @@
 #include <Delegate.h>
 #include <Network/UdpConnection.h>
 #include "Request.h"
+#include "Handler.h"
 
 namespace mDNS
 {
@@ -30,13 +31,13 @@ class Server : protected UdpConnection
 public:
 	/**
 	 * @brief Callback to be invoked for each received message
-	 * @retval bool Depends on operation
+	 * @retval bool See `onSend()`
 	 */
 	using MessageDelegate = Delegate<bool(Message& message)>;
 
 	/**
 	 * @brief Callback to be invoked with raw data (debugging, etc.)
-	 * @retval bool Depends on operation
+	 * @retval bool See `onPacket()`
 	 */
 	using PacketDelegate = Delegate<bool(IpAddress remoteIP, uint16_t remotePort, const uint8_t* data, size_t length)>;
 
@@ -56,9 +57,18 @@ class Server : protected UdpConnection
 	 * @brief Set callback to be invoked for each received message
 	 * @param callback Return false from callback to prevent message being passed to other clients
 	 */
-	void onMessage(MessageDelegate callback)
+	void addHandler(Handler& handler)
 	{
-		messageCallback = callback;
+		handlers.add(&handler);
+	}
+
+	/**
+	 * @brief Remove a message handler
+	 * @note If there are no more handlers then consider setting a timeout and then shutting the server down.
+	 */
+	void removeHandler(Handler& handler)
+	{
+		handlers.remove(&handler);
 	}
 
 	/**
@@ -106,7 +116,7 @@ class Server : protected UdpConnection
 		void onReceive(pbuf* buf, IpAddress remoteIP, uint16_t remotePort) override;
 	};
 
-	MessageDelegate messageCallback;
+	Handler::List handlers;
 	MessageDelegate sendCallback;
 	PacketDelegate packetCallback;
 	UdpOut out;

samples/Basic_Mdns/app/application.cpp

@@ -9,7 +9,25 @@
 #define WIFI_PWD "PleaseEnterPass"
 #endif
 
-DEFINE_FSTR_LOCAL(fstrSearchService, "_googlecast._tcp.local")
+class MessageHandler : public mDNS::Handler
+{
+public:
+	/*
+	 * Set the DNS record name we're interested in.
+	 * Used as a filter in our `onMessage` method.
+	 */
+	void setSearchName(const String& name)
+	{
+		searchName = name;
+	}
+
+	bool onMessage(mDNS::Message& message) override;
+
+private:
+	String searchName;
+};
+
+static MessageHandler myMessageHandler;
 
 #ifdef ARCH_HOST
 bool savePacket(IpAddress remoteIP, uint16_t remotePort, const uint8_t* data, size_t length)
@@ -31,20 +49,22 @@ bool savePacket(IpAddress remoteIP, uint16_t remotePort, const uint8_t* data, si
 }
 #endif
 
-bool handleMessage(mDNS::Message& message)
+bool MessageHandler::onMessage(mDNS::Message& message)
 {
 	mDNS::printMessage(Serial, message);
 
-	// Check if we're interested in this reponse
+	// Check if we're interested in this message
 	if(!message.isReply()) {
+		debug_i("Ignoring query");
 		return false;
 	}
 	auto answer = message[mDNS::ResourceType::PTR];
 	if(answer == nullptr) {
+		debug_i("Ignoring message: no PTR record");
 		return false;
 	}
-	if(answer->getName() != fstrSearchService) {
-		debug_i("Ignoring message");
+	if(answer->getName() != searchName) {
+		debug_i("Ignoring message: Name doesn't match");
 		return false;
 	}
 
@@ -80,13 +100,15 @@ bool handleMessage(mDNS::Message& message)
 
 void sendSearch()
 {
-	String name(fstrSearchService);
+	String name = F("_googlecast._tcp.local");
 
 	// To discover all DNS-SD registered services, use:
 	// name = F("_services._dns-sd._udp.local");
 
 	bool ok = mDNS::server.search(name);
 	debug_i("search('%s'): %s", name.c_str(), ok ? "OK" : "FAIL");
+	// Tell our handler what we're looking for
+	myMessageHandler.setSearchName(name);
 }
 
 void gotIP(IpAddress ip, IpAddress netmask, IpAddress gateway)
@@ -98,7 +120,7 @@ void gotIP(IpAddress ip, IpAddress netmask, IpAddress gateway)
 		printMessage(Serial, msg);
 		return true;
 	});
-	mDNS::server.onMessage(handleMessage);
+	mDNS::server.addHandler(myMessageHandler);
 #ifdef ARCH_HOST
 	mDNS::server.onPacket(savePacket);
 #endif