Implement SEQUENCE_LAST flag

Message Encoding.go

@@ -51,6 +51,11 @@ const (
 	ActionInfoStore = 3 // INFO_STORE Sender indicates storing provided data
 )
 
+// Actions in Response message
+const (
+	ActionSequenceLast = 0 // SEQUENCE_LAST Last response to the announcement in the sequence
+)
+
 // Features are sent as bit array in the Announcement message.
 const (
 	FeatureIPv4Listen = 0 // Sender listens on IPv4
@@ -726,9 +731,10 @@ createPacketLoop:
 			hashesNotFound = nil
 		}
 
+		raw[2] |= 1 << ActionSequenceLast // Indicate that no more responses will be sent in this sequence
 		packetsRaw = append(packetsRaw, raw[:packetSize])
 
-		if len(hash2Peers) == 0 && len(filesEmbed) == 0 && len(hashesNotFound) == 0 {
+		if len(hash2Peers) == 0 && len(filesEmbed) == 0 && len(hashesNotFound) == 0 { // this should always be the case here
 			return
 		}
 	}

Message Sequence.go

@@ -124,4 +124,16 @@ func msgValidateSequence(raw *MessageRaw) (valid bool, rtt time.Duration) {
 	return sequence.expires.After(time.Now()), rtt
 }
 
-// TODO: Manual invalidation of sequence number from high-level (once information request is considered handled).
+// msgInvalidateSequence invalidates the sequence number.
+func msgInvalidateSequence(raw *MessageRaw) {
+	// Only Response
+	if raw.Command != CommandResponse {
+		return
+	}
+
+	key := string(raw.SenderPublicKey.SerializeCompressed()) + strconv.FormatUint(uint64(raw.Sequence), 10)
+
+	sequencesMutex.Lock()
+	delete(sequences, key)
+	sequencesMutex.Unlock()
+}

Network.go

@@ -174,6 +174,10 @@ func packetWorker(packets <-chan networkWire) {
 
 		case CommandResponse: // Response
 			if response, _ := msgDecodeResponse(raw); response != nil {
+				if (response.Actions & (1 << ActionSequenceLast)) > 0 {
+					msgInvalidateSequence(raw)
+				}
+
 				peer.cmdResponse(response)
 			}