File content as of revision 0:9282d46b9f92:

/* NTPClient.cpp */
/* Copyright (C) 2012 mbed.org, MIT License
 *
 * 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.
 */
//Debug is disabled by default
#if 0
//Enable debug

#define __DEBUG__
#include <cstdio>
#define DBG(x, ...)     std::printf("[NTPClient : DBG]"x "\r\n", ##__VA_ARGS__);
#define WARN(x, ...)    std::printf("[NTPClient : WARN]"x "\r\n", ##__VA_ARGS__);
#define ERR(x, ...)     std::printf("[NTPClient : ERR]"x "\r\n", ##__VA_ARGS__);

#else

//Disable debug
#define DBG(x, ...)
#define WARN(x, ...)
#define ERR(x, ...)
#endif

#include "NetworkInterface.h"
#include "NTPClient.h"
#include "UDPSocket.h"
#include "mbed.h"                           //time() and set_time()

#define NTP_PORT            123
#define NTP_CLIENT_PORT     0               //Random port

#define NTP_TIMESTAMP_DELTA 2208988800ull   //Diff btw a UNIX timestamp (Starting Jan, 1st 1970) and a NTP timestamp (Starting Jan, 1st 1900)

NTPClient::NTPClient(NetworkInterface& _m_intf) :
    m_intf(_m_intf)
{ }

#ifdef htons
#undef htons
#endif /* htons */

#ifdef htonl
#undef htonl
#endif /* htonl */

#ifdef ntohs
#undef ntohs
#endif /* ntohs */

#ifdef ntohl
#undef ntohl
#endif /* ntohl */

#if ((__BYTE_ORDER__) == (__ORDER_LITTLE_ENDIAN__))
#define htons(x)    ((((x) & 0xff) << 8) | (((x) & 0xff00) >> 8))
#define ntohs(x)    htons(x)
#define htonl(x)    ((((x) & 0xff) << 24) | (((x) & 0xff00) << 8) | (((x) & 0xff0000UL) >> 8) | (((x) & 0xff000000UL) >> 24))
#define ntohl(x)    htonl(x)
#else
#define htons(x)    (x)
#define htonl(x)    (x)
#define ntohl(x)    (x)
#define ntohs(x)    (x)
#endif

/**
 * @brief
 * @note
 * @param
 * @retval
 */
NTPResult NTPClient::setTime(const char* host, uint16_t port, uint32_t timeout)
{
#ifdef __DEBUG__
    time_t  ctTime;
    ctTime = time(NULL);
    set_time(ctTime);
    DBG("Time is set to (UTC): %s", ctime(&ctTime));
#endif

    SocketAddress   address(0, port);
    int             r = m_intf.gethostbyname(host, &address);
    if (r) {
        printf("error: 'gethostbyname(\"%s\")' failed with code %d\r\n", host, r);
    }
    else
    if (!address) {
        printf("error: 'gethostbyname(\"%s\")' returned null IP address\r\n", host);
    }

    //printf ("address: %s\n\r",address.get_ip_address());
    //Create & bind socket
    if (m_sock.open(&m_intf) < 0)
        printf("ERROR sock open \n\r");
    m_sock.set_timeout(timeout);

    struct NTPPacket    pkt;
    memset(&pkt, 0, sizeof(NTPPacket));

    //Now ping the server and wait for response
    DBG("Ping");

    //Prepare NTP Packet:
    pkt.li = 0;         //Leap Indicator : No warning
    pkt.vn = 4;         //Version Number : 4
    pkt.mode = 3;       //Client mode
    pkt.stratum = 0;    //Not relevant here
    pkt.poll = 0;       //Not significant as well
    pkt.precision = 0;  //Neither this one is
    int ret = m_sock.sendto(address, (char*) &pkt, sizeof(NTPPacket));
    if (ret < 0) {
        ERR("Could not send packet %d", ret);
        m_sock.close();
        return NTP_CONN;
    }

    //Read response
    DBG("Pong");

    ret = m_sock.recvfrom(&address, (char*) &pkt, sizeof(NTPPacket));   // LICIO
    if (ret < 0) {
        ERR("Could not receive packet %d", ret);
        m_sock.close();
        return NTP_CONN;
    }

    if (ret < sizeof(NTPPacket)) {

        //TODO: Accept chunks
        ERR("Receive packet size does not match");
        m_sock.close();
        return NTP_PRTCL;
    }

    if (pkt.stratum == 0) {

        //Kiss of death message : Not good !
        ERR("Kissed to death!");
        m_sock.close();
        return NTP_PRTCL;
    }

    //Correct Endianness
    pkt.refTm_s = ntohl(pkt.refTm_s);
    pkt.refTm_f = ntohl(pkt.refTm_f);
    pkt.origTm_s = ntohl(pkt.origTm_s);
    pkt.origTm_f = ntohl(pkt.origTm_f);
    pkt.rxTm_s = ntohl(pkt.rxTm_s);
    pkt.rxTm_f = ntohl(pkt.rxTm_f);
    pkt.txTm_s = ntohl(pkt.txTm_s);
    pkt.txTm_f = ntohl(pkt.txTm_f);

    // see RFC 4330 p.13
    time_t  txTm = (time_t) (pkt.txTm_s - NTP_TIMESTAMP_DELTA);
    set_time(txTm);

#ifdef __DEBUG__
    ctTime = time(NULL);
    DBG("Time is now (UTC): %s", ctime(&ctTime));
#endif
    m_sock.close();

    return NTP_OK;
}