Switch from broadcast to multicast (ipv4)

builtin/mainmenu/tab_online.lua

@@ -17,32 +17,31 @@
 
 local function get_sorted_servers()
 	local servers = {
+		lan = {},
 		fav = {},
 		public = {},
 		incompatible = {}
 	}
 
+	local merged_serverlist = table.copy(serverlistmgr.servers)
+
 	--Special thanks to proller <proller@gmail.com> for letting use use the get_lan_servers function.
 	if minetest.settings:get_bool("serverlist_lan") then
 		if core.get_lan_servers then
-			servers.lan = core.get_lan_servers();
-
-			for _, server in ipairs(servers.lan) do
+			local lan = core.get_lan_servers()
+			for _, server in ipairs(lan) do
 				server.is_compatible = is_server_protocol_compat(server.proto_min, server.proto_max)
+				server.is_local = true
+				table.insert(merged_serverlist, server)
 			end
 		else
 			print("core.get_lan_servers isn't defined.")
-			servers.lan = {}
 		end
-	else
-		servers.lan = {}
 	end
 
-	print(dump(servers.lan))
-
 	local favs = serverlistmgr.get_favorites()
 	local taken_favs = {}
-	local result = menudata.search_result or serverlistmgr.servers
+	local result = menudata.search_result or merged_serverlist
 	for _, server in ipairs(result) do
 		server.is_favorite = false
 		for index, fav in ipairs(favs) do
@@ -56,7 +55,11 @@ local function get_sorted_servers()
 		if server.is_favorite then
 			table.insert(servers.fav, server)
 		elseif server.is_compatible then
-			table.insert(servers.public, server)
+			if server.is_local then
+				table.insert(servers.lan, server)
+			else
+				table.insert(servers.public, server)
+			end
 		else
 			table.insert(servers.incompatible, server)
 		end
@@ -389,6 +392,8 @@ local function main_button_handler(tabview, fields, name, tabdata)
 
 			serverlistmgr.add_favorite(server)
 
+			print("Adding this server to favorites: \n"..dump(server))
+
 			gamedata.servername        = server.name
 			gamedata.serverdescription = server.description
 

src/network/lan.cpp

@@ -68,13 +68,34 @@ typedef int socklen_t;
 typedef int socket_t;
 #endif
 
+const char* adv_multicast_addr = "224.1.1.1";
 const static unsigned short int adv_port = 29998;
 static std::string ask_str;
 
+bool use_ipv6 = true;
+
 lan_adv::lan_adv() : Thread("lan_adv")
 {
 }
 
+lan_adv::~lan_adv() 
+{
+	if (!stopRequested()) {
+		stop();
+		warningstream << "Thread Had to be forced to stop correctly." << std::endl;
+	} 
+
+	if (stopRequested()) warningstream << "Lan Adv Thread is stopping." << std::endl;
+
+	if (server_port) {
+		Json::Value answer_json;
+		answer_json["port"] = server_port;
+		answer_json["cmd"] = "shutdown";
+		send_string(fastWriteJson(answer_json));
+		warningstream << "Server shut down message sent." << std::endl;
+	}
+}
+
 void lan_adv::ask()
 {
 	if (!isRunning()) start();
@@ -94,18 +115,33 @@ void lan_adv::send_string(const std::string &str)
 		sockaddr_in addr = {};
 		addr.sin_family = AF_INET;
 		addr.sin_port = htons(adv_port);
-		addr.sin_addr.s_addr = htonl(INADDR_BROADCAST);
 		UDPSocket socket_send(false);
-		int set_option_on = 1;
-		setsockopt(socket_send.GetHandle(), SOL_SOCKET, SO_BROADCAST,
-				(const char *)&set_option_on, sizeof(set_option_on));
+
+		// Full discloser, the use of inet_proto and the mreq stucture 
+		// were suggested by ai.
+
+		inet_pton(AF_INET, adv_multicast_addr, &(addr.sin_addr));
+
+		struct ip_mreq mreq;
+
+		mreq.imr_multiaddr.s_addr = inet_addr(adv_multicast_addr);
+		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
+		
+
+		setsockopt(socket_send.GetHandle(), IPPROTO_IP, IP_ADD_MEMBERSHIP,
+				(const char *)&mreq, sizeof(mreq));
+
+		//int set_option_on = 2;
+		//setsockopt(socket_send.GetHandle(), SOL_SOCKET, IP_MULTICAST_TTL,
+		//		(const char *)&set_option_on, sizeof(set_option_on));
+
 		socket_send.Send(Address(addr), str.c_str(), str.size());
 	} catch (const std::exception &e) {
 		verbosestream << "udp broadcast send4 fail " << e.what() << "\n";
 	}
 
 	std::vector<uint32_t> scopes;
-// todo: windows and android
+	// todo: windows and android
 
 #if HAVE_IFADDRS
 	struct ifaddrs *ifaddr = nullptr, *ifa = nullptr;
@@ -118,7 +154,7 @@ void lan_adv::send_string(const std::string &str)
 				continue;
 
 			auto sa = *((struct sockaddr_in6 *)ifa->ifa_addr);
-			if (sa.sin6_scope_id)
+		if (sa.sin6_scope_id)
 				scopes.push_back(sa.sin6_scope_id);
 
 			/*errorstream<<"in=" << ifa->ifa_name << " a="<<Address(*((struct sockaddr_in6*)ifa->ifa_addr)).serializeString()<<" ba=" << ifa->ifa_broadaddr <<" sc=" << sa.sin6_scope_id <<" fl=" <<  ifa->ifa_flags
@@ -147,8 +183,8 @@ void lan_adv::send_string(const std::string &str)
 				addr.sin6_port = htons(adv_port);
 				UDPSocket socket_send(true);
 				int set_option_on = 1;
-				setsockopt(socket_send.GetHandle(), SOL_SOCKET, SO_BROADCAST,
-						(const char *)&set_option_on, sizeof(set_option_on));
+				//setsockopt(socket_send.GetHandle(), SOL_SOCKET, IPV6_MULTICAST_HOPS,
+				//		(const char *)&set_option_on, sizeof(set_option_on));
 				auto use_scopes = scopes;
 				if (addr.sin6_scope_id) {
 					use_scopes.clear();
@@ -169,7 +205,7 @@ void lan_adv::send_string(const std::string &str)
 void lan_adv::serve(unsigned short port)
 {
 	server_port = port;
-	if (isRunning()) stop();
+	stop();
 	start(); 
 }
 
@@ -187,8 +223,13 @@ void *lan_adv::run()
 	setsockopt(socket_recv.GetHandle(), SOL_SOCKET, SO_REUSEPORT,
 			(const char *)&set_option_on, sizeof(set_option_on));
 #endif
-	setsockopt(socket_recv.GetHandle(), SOL_SOCKET, SO_BROADCAST,
-			(const char *)&set_option_on, sizeof(set_option_on));
+	struct ip_mreq mreq;
+
+	mreq.imr_multiaddr.s_addr = inet_addr(adv_multicast_addr);
+	mreq.imr_interface.s_addr = htonl(INADDR_ANY);
+
+	setsockopt(socket_recv.GetHandle(), IPPROTO_IP, IP_ADD_MEMBERSHIP,
+			(const char *)&mreq, sizeof(mreq));
 	setsockopt(socket_recv.GetHandle(), IPPROTO_IPV6, IPV6_V6ONLY,
 			(const char *)&set_option_off, sizeof(set_option_off));
 	socket_recv.setTimeoutMs(200);
@@ -254,11 +295,11 @@ void *lan_adv::run()
 
 				server["clients"] = clients_num.load();
 				answer_str = fastWriteJson(server);
-
 				limiter[addr_str] = now + 3000;
-				UDPSocket socket_send(true);
-				addr.setPort(adv_port);
-				socket_send.Send(addr, answer_str.c_str(), answer_str.size());
+				send_string(answer_str);
+				//UDPSocket socket_send(true);
+				//addr.setPort(adv_port);
+				//socket_send.Send(addr, answer_str.c_str(), answer_str.size());
 			}
 		} else {
 			if (p["cmd"] == "ask") {
@@ -284,13 +325,6 @@ void *lan_adv::run()
 		END_DEBUG_EXCEPTION_HANDLER;
 	}
 
-	if (server_port) {
-		Json::Value answer_json;
-		answer_json["port"] = server_port;
-		answer_json["cmd"] = "shutdown";
-		send_string(fastWriteJson(answer_json));
-	}
-
 	END_DEBUG_EXCEPTION_HANDLER;
 
 	return nullptr;

src/network/lan.h

@@ -32,6 +32,7 @@ public:
 	void *run();
 
 	lan_adv();
+	~lan_adv();
 	void ask();
 	void send_string(const std::string &str);