feat: Delay M-SEARCH response by a random value according to MX header (#844)

libsrc/ssdp/SSDPDiscover.cpp

@@ -12,7 +12,7 @@ static const quint16      SSDP_PORT(1900);
 static const QString UPNP_DISCOVER_MESSAGE = "M-SEARCH * HTTP/1.1\r\n"
                                           "HOST: 239.255.255.250:1900\r\n"
                                           "MAN: \"ssdp:discover\"\r\n"
-										  "MX: 1\r\n"
+                                          "MX: 1\r\n"
                                           "ST: %1\r\n"
                                           "\r\n";
 
@@ -49,7 +49,6 @@ const QString SSDPDiscover::getFirstService(const searchType& type, const QStrin
 			QByteArray datagram;
 			while (_udpSocket->hasPendingDatagrams())
 			{
-
 				datagram.resize(_udpSocket->pendingDatagramSize());
 				QHostAddress sender;
 				quint16 senderPort;
@@ -163,13 +162,15 @@ void SSDPDiscover::readPendingDatagrams()
 			if(entry.contains("HTTP/1.1"))
 				continue;
 
-			// split into key:vale, be aware that value field may contain also a ":"
+			// split into key:value, be aware that value field may contain also a ":"
 			entry = entry.simplified();
 			int pos = entry.indexOf(":");
 			if(pos == -1)
 				continue;
 
-			headers[entry.left(pos).trimmed().toLower()] = entry.mid(pos+1).trimmed();
+			const QString key = entry.left(pos).trimmed().toLower();
+			const QString value = entry.mid(pos + 1).trimmed();
+			headers[key] = value;
 		}
 
 		// verify ssdp spec
@@ -185,7 +186,7 @@ void SSDPDiscover::readPendingDatagrams()
 			_usnList << headers.value("usn");
 			//Debug(_log, "Received msearch response from '%s:%d'. Search target: %s",QSTRING_CSTR(sender.toString()), senderPort, QSTRING_CSTR(headers.value("st")));
 			QUrl url(headers.value("location"));
-			emit newService(url.host()+":"+QString::number(url.port()));
+			emit newService(url.host() + ":" + QString::number(url.port()));
 		}
 	}
 }
@@ -194,7 +195,5 @@ void SSDPDiscover::sendSearch(const QString& st)
 {
 	const QString msg = UPNP_DISCOVER_MESSAGE.arg(st);
 
-    _udpSocket->writeDatagram(msg.toUtf8(),
+	_udpSocket->writeDatagram(msg.toUtf8(), QHostAddress(SSDP_ADDR), SSDP_PORT);
-							 QHostAddress(SSDP_ADDR),
-							 SSDP_PORT);
 }

libsrc/ssdp/SSDPHandler.cpp

@@ -150,13 +150,28 @@ const QString SSDPHandler::getLocalAddress()
 
 void SSDPHandler::handleMSearchRequest(const QString& target, const QString& mx, const QString address, const quint16 & port)
 {
-	// TODO Response delay according to MX field (sec) random between 0 and MX
+	const auto respond = [=] () {
+		// when searched for all devices / root devices / basic device
+		if(target == "ssdp:all")
+			sendMSearchResponse(SSDP_HYPERION_ST, address, port);
+		else if(target == "upnp:rootdevice" || target == "urn:schemas-upnp-org:device:basic:1" || target == SSDP_HYPERION_ST)
+			sendMSearchResponse(target, address, port);
+	};
 
-	// when searched for all devices / root devices / basic device
+	bool ok = false;
-	if(target == "ssdp:all")
+	int maxDelay = mx.toInt(&ok);
-		sendMSearchResponse(SSDP_HYPERION_ST, address, port);
+	if (ok)
-	else if(target == "upnp:rootdevice" || target == "urn:schemas-upnp-org:device:basic:1" || target == SSDP_HYPERION_ST)
+	{
-		sendMSearchResponse(target, address, port);
+		/* Pick a random delay between 0 and MX seconds */
+		int randomDelay = qrand() % (maxDelay * 1000);
+		QTimer::singleShot(randomDelay, respond);
+	}
+	else
+	{
+		/* MX Header is not valid.
+		 * Send response without delay */
+		respond();
+	}
 }
 
 const QString SSDPHandler::getDescAddress()

libsrc/ssdp/SSDPServer.cpp

@@ -163,8 +163,8 @@ void SSDPServer::readPendingDatagrams()
 
 		if (headers.value("man") == "\"ssdp:discover\"")
 		{
-	    	//Debug(_log, "Received msearch from '%s:%d'. Search target: %s",QSTRING_CSTR(sender.toString()), senderPort, QSTRING_CSTR(headers.value("st")));
+			//Debug(_log, "Received msearch from '%s:%d'. Search target: %s",QSTRING_CSTR(sender.toString()), senderPort, QSTRING_CSTR(headers.value("st")));
-    		emit msearchRequestReceived(headers.value("st"), headers.value("mx"), sender.toString(), senderPort);
+			emit msearchRequestReceived(headers.value("st"), headers.value("mx"), sender.toString(), senderPort);
 		}
     }
 }
@@ -181,9 +181,7 @@ void SSDPServer::sendMSearchResponse(const QString& st, const QString& senderIp,
 		, _jssPort
 		, _name );
 
-	_udpSocket->writeDatagram(message.toUtf8(),
+	_udpSocket->writeDatagram(message.toUtf8(), QHostAddress(senderIp), senderPort);
-								 QHostAddress(senderIp),
-								 senderPort);
 }
 
 void SSDPServer::sendByeBye(const QString& st)
@@ -192,11 +190,8 @@ void SSDPServer::sendByeBye(const QString& st)
 
 	// we repeat 3 times
 	quint8 rep = 0;
-	while(rep < 3) {
+	while(rep++ < 3) {
-		_udpSocket->writeDatagram(message.toUtf8(),
+		_udpSocket->writeDatagram(message.toUtf8(), QHostAddress(SSDP_ADDR), SSDP_PORT);
-								 QHostAddress(SSDP_ADDR),
-								 SSDP_PORT);
-		rep++;
 	}
 }
 
@@ -215,11 +210,8 @@ void SSDPServer::sendAlive(const QString& st)
 
 	// we repeat 3 times
 	quint8 rep = 0;
-	while(rep < 3) {
+	while(rep++ < 3) {
-		_udpSocket->writeDatagram(message.toUtf8(),
+		_udpSocket->writeDatagram(message.toUtf8(), QHostAddress(SSDP_ADDR), SSDP_PORT);
-								 QHostAddress(SSDP_ADDR),
-								 SSDP_PORT);
-		rep++;
 	}
 }
 
@@ -229,7 +221,5 @@ void SSDPServer::sendUpdate(const QString& st)
 		, st
 		, _uuid+"::"+st );
 
-	_udpSocket->writeDatagram(message.toUtf8(),
+	_udpSocket->writeDatagram(message.toUtf8(), QHostAddress(SSDP_ADDR), SSDP_PORT);
-							 QHostAddress(SSDP_ADDR),
-							 SSDP_PORT);
 }