NTPClient.cpp

/**
 * The MIT License (MIT)
 * Copyright (c) 2015 by Fabrice Weinberg
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "NTPClient.h"

NTPClient::NTPClient(UDP& udp) {
  this->_udp            = &udp;
}

NTPClient::NTPClient(UDP& udp, int timeOffset) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
}

NTPClient::NTPClient(UDP& udp, const char* poolServerName) {
  this->_udp            = &udp;
  this->_poolServerName = poolServerName;
}

NTPClient::NTPClient(UDP& udp, const char* poolServerName, int timeOffset) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
  this->_poolServerName = poolServerName;
}

NTPClient::NTPClient(UDP& udp, const char* poolServerName, int timeOffset, int updateInterval) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
  this->_poolServerName = poolServerName;
  this->_updateInterval = updateInterval;
}

void NTPClient::begin() {
  this->begin(NTP_DEFAULT_LOCAL_PORT);
}

void NTPClient::begin(int port) {
  this->_port = port;

  this->_udp->begin(this->_port);

  this->_udpSetup = true;
}

bool NTPClient::isValid(byte * ntpPacket) {
  //Perform a few validity checks on the packet
  if((ntpPacket[0] & 0b11000000) == 0b11000000)		//Check for LI=UNSYNC
      return false;
      
  if((ntpPacket[0] & 0b00111000) >> 3 < 0b100)		//Check for Version >= 4
      return false;
      
  if((ntpPacket[0] & 0b00000111) != 0b100)			//Check for Mode == Server
      return false;
      
  if((ntpPacket[1] < 1) || (ntpPacket[1] > 15))		//Check for valid Stratum
      return false;
  if(	ntpPacket[16] == 0 && ntpPacket[17] == 0 && 
      ntpPacket[18] == 0 && ntpPacket[19] == 0 &&
      ntpPacket[20] == 0 && ntpPacket[21] == 0 &&
      ntpPacket[22] == 0 && ntpPacket[22] == 0)		//Check for ReferenceTimestamp != 0
      return false;
  return true;
}

bool NTPClient::forceUpdate() {
  #ifdef DEBUG_NTPClient
    Serial.println("Update from NTP Server");
  #endif

  this->sendNTPPacket();

  // Wait till data is there or timeout...
  byte timeout = 0;
  int cb = 0;
  do {
    delay ( 10 );
    cb = this->_udp->parsePacket();
    if(cb > 0) {
      this->_udp->read(this->_packetBuffer, NTP_PACKET_SIZE);
      if(!this->isValid(this->_packetBuffer))
        cb = 0;
    }
    if (timeout > 100) return false; // timeout after 1000 ms
    timeout++;
  } while (cb == 0);

  this->_lastUpdate = millis() - (10 * (timeout + 1)); // Account for delay in reading the time

  //this->_udp->read(this->_packetBuffer, NTP_PACKET_SIZE);

  unsigned long highWord = word(this->_packetBuffer[40], this->_packetBuffer[41]);
  unsigned long lowWord = word(this->_packetBuffer[42], this->_packetBuffer[43]);
  // combine the four bytes (two words) into a long integer
  // this is NTP time (seconds since Jan 1 1900):
  unsigned long secsSince1900 = highWord << 16 | lowWord;

  this->_currentEpoc = secsSince1900 - SEVENZYYEARS;

  return true;
}

bool NTPClient::update() {
  if ((millis() - this->_lastUpdate >= this->_updateInterval)     // Update after _updateInterval
    || this->_lastUpdate == 0) {                                // Update if there was no update yet.
    if (!this->_udpSetup) this->begin();                         // setup the UDP client if needed
    return this->forceUpdate();
  }
  return true;
}

unsigned long NTPClient::getEpochTime() {
  return //this->_timeOffset + // User offset
         this->_currentEpoc + // Epoc returned by the NTP server
         ((millis() - this->_lastUpdate) / 1000); // Time since last update
}

int NTPClient::getDay() {
  //return (((this->getEpochTime()  / 86400L) + 4 ) % 7); //0 is Sunday
  unsigned long time = this->getEpochTime();
  time += this->_timeOffset; // User offset
  return (((time / 86400L) + 4 ) % 7); //0 is Sunday
}

int NTPClient::getHours() {
  //return ((this->getEpochTime()  % 86400L) / 3600);
  unsigned long time = this->getEpochTime();
  time += this->_timeOffset; // User offset
  return ((time  % 86400L) / 3600);
}
int NTPClient::getMinutes() {
  //return ((this->getEpochTime() % 3600) / 60);
  unsigned long time = this->getEpochTime();
  time += this->_timeOffset; // User offset
  return ((time % 3600) / 60);
}
int NTPClient::getSeconds() {
  //return (this->getEpochTime() % 60);
  unsigned long time = this->getEpochTime();
  time += this->_timeOffset; // User offset
  return (time % 60);
}

String NTPClient::getFormattedTime() {
  unsigned long rawTime = this->getEpochTime();
  rawTime += this->_timeOffset; // User offset
  unsigned long hours = (rawTime % 86400L) / 3600;
  String hoursStr = hours < 10 ? "0" + String(hours) : String(hours);

  unsigned long minutes = (rawTime % 3600) / 60;
  String minuteStr = minutes < 10 ? "0" + String(minutes) : String(minutes);

  unsigned long seconds = rawTime % 60;
  String secondStr = seconds < 10 ? "0" + String(seconds) : String(seconds);

  return hoursStr + ":" + minuteStr + ":" + secondStr;
}

void NTPClient::end() {
  this->_udp->stop();

  this->_udpSetup = false;
}

void NTPClient::setTimeOffset(int timeOffset) {
  this->_timeOffset     = timeOffset;
}

void NTPClient::setUpdateInterval(int updateInterval) {
  this->_updateInterval = updateInterval;
}

void NTPClient::sendNTPPacket() {
  // set all bytes in the buffer to 0
  memset(this->_packetBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  // (see URL above for details on the packets)
  this->_packetBuffer[0] = 0b11100011;   // LI, Version, Mode
  this->_packetBuffer[1] = 0;     // Stratum, or type of clock
  this->_packetBuffer[2] = 6;     // Polling Interval
  this->_packetBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  this->_packetBuffer[12]  = 49;
  this->_packetBuffer[13]  = 0x4E;
  this->_packetBuffer[14]  = 49;
  this->_packetBuffer[15]  = 52;

  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:
  this->_udp->beginPacket(this->_poolServerName, 123); //NTP requests are to port 123
  this->_udp->write(this->_packetBuffer, NTP_PACKET_SIZE);
  this->_udp->endPacket();
}

NTPClient.h

#pragma once

#include "Arduino.h"

#include <Udp.h>

#define SEVENZYYEARS 2208988800UL
#define NTP_PACKET_SIZE 48
#define NTP_DEFAULT_LOCAL_PORT 1337
#define DEBUG_NTPClient 1

class NTPClient {
  private:
    UDP*          _udp;
    bool          _udpSetup       = false;

    const char*   _poolServerName = "europe.pool.ntp.org"; // Default time server
    int           _port           = NTP_DEFAULT_LOCAL_PORT;
    int           _timeOffset     = 0;

    unsigned int  _updateInterval = 60000;  // In ms

    unsigned long _currentEpoc    = 0;      // In s
    unsigned long _lastUpdate     = 0;      // In ms

    byte          _packetBuffer[NTP_PACKET_SIZE];

    void          sendNTPPacket();
    bool          isValid(byte * ntpPacket);

  public:
    NTPClient(UDP& udp);
    NTPClient(UDP& udp, int timeOffset);
    NTPClient(UDP& udp, const char* poolServerName);
    NTPClient(UDP& udp, const char* poolServerName, int timeOffset);
    NTPClient(UDP& udp, const char* poolServerName, int timeOffset, int updateInterval);

    /**
     * Starts the underlying UDP client with the default local port
     */
    void begin();

    /**
     * Starts the underlying UDP client with the specified local port
     */
    void begin(int port);

    /**
     * This should be called in the main loop of your application. By default an update from the NTP Server is only
     * made every 60 seconds. This can be configured in the NTPClient constructor.
     *
     * @return true on success, false on failure
     */
    bool update();

    /**
     * This will force the update from the NTP Server.
     *
     * @return true on success, false on failure
     */
    bool forceUpdate();

    int getDay();
    int getHours();
    int getMinutes();
    int getSeconds();

    /**
     * Changes the time offset. Useful for changing timezones dynamically
     */
    void setTimeOffset(int timeOffset);

    /**
     * Set the update interval to another frequency. E.g. useful when the
     * timeOffset should not be set in the constructor
     */
    void setUpdateInterval(int updateInterval);

    /**
     * @return time formatted like `hh:mm:ss`
     */
    String getFormattedTime();

    /**
     * @return time in seconds since Jan. 1, 1970
     */
    unsigned long getEpochTime();

    /**
     * Stops the underlying UDP client
     */
    void end();
};