NTPClient: ignore invalid timestamps

SmingHub · Feb 3, 2020 · be8ae17 · be8ae17
1 parent 8883768
commit be8ae17
Showing 1 changed file with 24 additions and 18 deletions.
diff --git a/Sming/Core/Network/NtpClient.cpp b/Sming/Core/Network/NtpClient.cpp
@@ -132,28 +132,34 @@ void NtpClient::onReceive(pbuf* buf, IpAddress remoteIP, uint16_t remotePort)
 	uint8_t ver = (versionMode & 0b00111000) >> 3;
 	uint8_t mode = (versionMode & 0x07);
 
-	if(mode == NTP_MODE_SERVER && (ver == NTP_VERSION || ver == (NTP_VERSION - 1))) {
-		//Most likely a correct NTP packet received.
+	if(mode != NTP_MODE_SERVER || (ver != NTP_VERSION && ver != (NTP_VERSION - 1))) {
+		// Got a dodgy packet so treat it as we would a response failure
+		startTimer(NTP_RESPONSE_TIMEOUT_MS);
+		return;
+	}
 
-		uint32_t timestamp;
-		pbuf_copy_partial(buf, &timestamp, sizeof(timestamp), 40); // Copy only timestamp.
-		timestamp = ntohl(timestamp);
+	//Most likely a correct NTP packet received.
+	uint32_t timestamp;
+	pbuf_copy_partial(buf, &timestamp, sizeof(timestamp), 40); // Copy only timestamp.
+	timestamp = ntohl(timestamp);
 
-		// Unix time starts on Jan 1 1970, subtract 70 years:
-		uint32_t epoch = timestamp - 0x83AA7E80;
+	if (timestamp == 0) {
+		// Got a invalid timestamp - retry
+		startTimer(NTP_RESPONSE_TIMEOUT_MS);
+		return;
+	}
 
-		if(autoUpdateSystemClock) {
-			SystemClock.setTime(epoch, eTZ_UTC); // update systemclock utc value
-		}
+	// Unix time starts on Jan 1 1970, subtract 70 years:
+	uint32_t epoch = timestamp - 0x83AA7E80;
 
-		if(delegateCompleted) {
-			delegateCompleted(*this, epoch);
-		}
+	if(autoUpdateSystemClock) {
+		SystemClock.setTime(epoch, eTZ_UTC); // update systemclock utc value
+	}
 
-		// If auto query is enabled, schedule the next check
-		setAutoQuery(autoQueryEnabled);
-	} else {
-		// Got a dodgy packet so treat it as we would a response failure
-		startTimer(NTP_RESPONSE_TIMEOUT_MS);
+	if(delegateCompleted) {
+		delegateCompleted(*this, epoch);
 	}
+
+	// If auto query is enabled, schedule the next check
+	setAutoQuery(autoQueryEnabled);
 }