Fixed bug that caused the wrong message to be signed

process() altered the message buffer pending signing when
called in sign() causing the wrong message to be sent to the
signing backend. This is resolved by copying the original
message before processing incoming messages to make sure
the original message is kept. After it is successfully signed,
it is copied back to its original location again.
Also, the old 'ack' message buffer is renamed to tmpMsg to
indicate its use as a temporary message buffer for various
purposes.

libraries/MySensors/MySensor.cpp

@@ -349,12 +349,12 @@ boolean MySensor::process() {
 		// Check if sender requests an ack back.
 		if (mGetRequestAck(msg)) {
 			// Copy message
-			ack = msg;
-			mSetRequestAck(ack,false); // Reply without ack flag (otherwise we would end up in an eternal loop)
-			mSetAck(ack,true);
-			ack.sender = nc.nodeId;
-			ack.destination = msg.sender;
-			sendRoute(ack);
+			tmpMsg = msg;
+			mSetRequestAck(tmpMsg,false); // Reply without ack flag (otherwise we would end up in an eternal loop)
+			mSetAck(tmpMsg,true);
+			tmpMsg.sender = nc.nodeId;
+			tmpMsg.destination = msg.sender;
+			sendRoute(tmpMsg);
 		}
 
 		if (command == C_INTERNAL) {
@@ -591,18 +591,21 @@ int8_t MySensor::sleep(uint8_t interrupt1, uint8_t mode1, uint8_t interrupt2, ui
 }
 
 bool MySensor::sign(MyMessage &message) {
-	MyMessage msgNonce;
-	if (!sendRoute(build(msgNonce, nc.nodeId, message.destination, message.sensor, C_INTERNAL, I_GET_NONCE, false).set(""))) {
+	if (!sendRoute(build(tmpMsg, nc.nodeId, message.destination, message.sensor, C_INTERNAL, I_GET_NONCE, false).set(""))) {
 		return false;
 	} else {
 		// We have to wait for the nonce to arrive before we can sign our original message
 		// Other messages could come in-between. We trust process() takes care of them
 		unsigned long enter = millis();
+		msgSign = message; // Copy the message to sign since message buffer might be touched in process()
 		while (millis() - enter < 5000) {
 			if (process()) {
-				if (getLastMessage().type == I_GET_NONCE_RESPONSE) {
+				if (mGetCommand(getLastMessage()) == C_INTERNAL && getLastMessage().type == I_GET_NONCE_RESPONSE) {
 					// Proceed with signing if nonce has been received
-					if (signer.putNonce(getLastMessage()) && signer.signMsg(message)) return true;
+					if (signer.putNonce(getLastMessage()) && signer.signMsg(msgSign)) {
+						message = msgSign; // Write the signed message back
+						return true;
+					}
 					break;
 				}
 			}

libraries/MySensors/MySensor.h

@@ -246,7 +246,8 @@ class MySensor
 	uint16_t doSign[16]; // Bitfield indicating which sensors require signed communication
 
 	MyMessage msg;  // Buffer for incoming messages.
-	MyMessage ack;  // Buffer for ack messages.
+	MyMessage tmpMsg ;  // Buffer for temporary messages (acks and nonces among others).
+	MyMessage msgSign;  // Buffer for message to sign.
 
 	MyRFDriverClass radio;