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validate NTP responses (fixes #3515)
* purge old (not yet processes) NTP responses * validate server responses before updating WLED time * purge receive buffer when package is rejected (avoids mem leak on esp32)
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@ -375,7 +375,8 @@
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#define SUBPAGE_JS 254
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#define SUBPAGE_JS 254
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#define SUBPAGE_WELCOME 255
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#define SUBPAGE_WELCOME 255
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#define NTP_PACKET_SIZE 48
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#define NTP_PACKET_SIZE 48 // size of NTP recive buffer
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#define NTP_MIN_PACKET_SIZE 48 // min expected size - NTP v4 allows for "extended information" appended to the standard fields
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//maximum number of rendered LEDs - this does not have to match max. physical LEDs, e.g. if there are virtual busses
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//maximum number of rendered LEDs - this does not have to match max. physical LEDs, e.g. if there are virtual busses
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#ifndef MAX_LEDS
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#ifndef MAX_LEDS
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@ -199,6 +199,9 @@ void handleNetworkTime()
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{
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{
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if (millis() - ntpPacketSentTime > 10000)
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if (millis() - ntpPacketSentTime > 10000)
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{
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{
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#ifdef ARDUINO_ARCH_ESP32 // I had problems using udp.flush() on 8266
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while (ntpUdp.parsePacket() > 0) ntpUdp.flush(); // flush any existing packets
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#endif
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sendNTPPacket();
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sendNTPPacket();
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ntpPacketSentTime = millis();
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ntpPacketSentTime = millis();
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}
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}
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@ -239,16 +242,38 @@ void sendNTPPacket()
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ntpUdp.endPacket();
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ntpUdp.endPacket();
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}
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}
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static bool isValidNtpResponse(byte * ntpPacket) {
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// Perform a few validity checks on the packet
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// based on https://github.com/taranais/NTPClient/blob/master/NTPClient.cpp
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if((ntpPacket[0] & 0b11000000) == 0b11000000) return false; //reject LI=UNSYNC
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// if((ntpPacket[0] & 0b00111000) >> 3 < 0b100) return false; //reject Version < 4
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if((ntpPacket[0] & 0b00000111) != 0b100) return false; //reject Mode == Server
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if((ntpPacket[1] < 1) || (ntpPacket[1] > 15)) return false; //reject invalid Stratum
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if( ntpPacket[16] == 0 && ntpPacket[17] == 0 &&
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ntpPacket[18] == 0 && ntpPacket[19] == 0 &&
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ntpPacket[20] == 0 && ntpPacket[21] == 0 &&
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ntpPacket[22] == 0 && ntpPacket[23] == 0) //reject ReferenceTimestamp == 0
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return false;
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return true;
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}
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bool checkNTPResponse()
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bool checkNTPResponse()
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{
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{
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int cb = ntpUdp.parsePacket();
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int cb = ntpUdp.parsePacket();
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if (!cb) return false;
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if (cb < NTP_MIN_PACKET_SIZE) {
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#ifdef ARDUINO_ARCH_ESP32 // I had problems using udp.flush() on 8266
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if (cb > 0) ntpUdp.flush(); // this avoids memory leaks on esp32
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#endif
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return false;
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}
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uint32_t ntpPacketReceivedTime = millis();
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uint32_t ntpPacketReceivedTime = millis();
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DEBUG_PRINT(F("NTP recv, l="));
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DEBUG_PRINT(F("NTP recv, l="));
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DEBUG_PRINTLN(cb);
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DEBUG_PRINTLN(cb);
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byte pbuf[NTP_PACKET_SIZE];
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byte pbuf[NTP_PACKET_SIZE];
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ntpUdp.read(pbuf, NTP_PACKET_SIZE); // read the packet into the buffer
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ntpUdp.read(pbuf, NTP_PACKET_SIZE); // read the packet into the buffer
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if (!isValidNtpResponse(pbuf)) return false; // verify we have a valid response to client
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Toki::Time arrived = toki.fromNTP(pbuf + 32);
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Toki::Time arrived = toki.fromNTP(pbuf + 32);
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Toki::Time departed = toki.fromNTP(pbuf + 40);
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Toki::Time departed = toki.fromNTP(pbuf + 40);
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