NTPClient.cpp

00001 /* NTPClient.cpp */
00002 /* Copyright (C) 2012 mbed.org, MIT License
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
00005  * and associated documentation files (the "Software"), to deal in the Software without restriction,
00006  * including without limitation the rights to use, copy, modify, merge, publish, distribute,
00007  * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
00008  * furnished to do so, subject to the following conditions:
00009  *
00010  * The above copyright notice and this permission notice shall be included in all copies or
00011  * substantial portions of the Software.
00012  *
00013  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
00014  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00015  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
00016  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00017  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00018  */
00019 
00020 //Debug is disabled by default
00021 #if 1
00022 //Enable debug
00023 #define __DEBUG__
00024 #include <cstdio>
00025 #define DBG(x, ...) std::printf("[NTPClient : DBG]"x"\r\n", ##__VA_ARGS__); 
00026 #define WARN(x, ...) std::printf("[NTPClient : WARN]"x"\r\n", ##__VA_ARGS__); 
00027 #define ERR(x, ...) std::printf("[NTPClient : ERR]"x"\r\n", ##__VA_ARGS__); 
00028 
00029 #else
00030 //Disable debug
00031 #define DBG(x, ...) 
00032 #define WARN(x, ...)
00033 #define ERR(x, ...) 
00034 
00035 #endif
00036 
00037 #include "NTPClient.h"
00038 
00039 #include "UDPSocket.h"
00040 
00041 #include "mbed.h" //time() and set_time()
00042 #include "def.h"
00043 #define NTP_PORT 123
00044 #define NTP_CLIENT_PORT 0 //Random port
00045 #define NTP_TIMESTAMP_DELTA 2208988800ull //Diff btw a UNIX timestamp (Starting Jan, 1st 1970) and a NTP timestamp (Starting Jan, 1st 1900)
00046 
00047 NTPClient::NTPClient(NetworkInterface& p_networkInterface) : m_sock(), m_net(p_networkInterface) {
00048 }
00049 
00050 NTPResult NTPClient::setTime(const char* host, uint16_t port, uint32_t timeout)
00051 {
00052 #ifdef __DEBUG__
00053   time_t ctTime;
00054   ctTime = time(NULL);
00055   DBG("Time is set to (UTC): %s", ctime(&ctTime));
00056 #endif
00057 
00058   if( m_sock.open(&m_net) != 0){ DBG("Open"); return NTP_CONN;}
00059 
00060   //Create & bind socket
00061   DBG("Binding socket");
00062   if( m_sock.bind(99) != 0){ DBG("Bind"); return NTP_CONN;}
00063 
00064   struct NTPPacket pkt;
00065 
00066   //Now ping the server and wait for response
00067   DBG("Ping");
00068   //Prepare NTP Packet:
00069   pkt.li = 0; //Leap Indicator : No warning
00070   pkt.vn = 4; //Version Number : 4
00071   pkt.mode = 3; //Client mode
00072   pkt.stratum = 0; //Not relevant here
00073   pkt.poll = 0; //Not significant as well
00074   pkt.precision = 0; //Neither this one is
00075 
00076   pkt.rootDelay = 0; //Or this one
00077   pkt.rootDispersion = 0; //Or that one
00078   pkt.refId = 0; //...
00079 
00080   pkt.refTm_s = 0;
00081   pkt.origTm_s = 0;
00082   pkt.rxTm_s = 0;
00083   pkt.txTm_s = htonl( NTP_TIMESTAMP_DELTA + time(NULL) ); //WARN: We are in LE format, network byte order is BE
00084 
00085   pkt.refTm_f = pkt.origTm_f = pkt.rxTm_f = pkt.txTm_f = 0;
00086 
00087   SocketAddress outEndpoint (host, port);
00088     
00089   //Set timeout, non-blocking and wait using select
00090   int ret = m_sock.sendto(host, port, (char*)&pkt, sizeof(NTPPacket) );
00091   if (ret < 0 )
00092   {
00093     ERR("Could not send packet (%d)", ret);
00094     m_sock.close();
00095     return NTP_CONN;
00096   }
00097 
00098   //Read response
00099   SocketAddress inEndpoint;
00100 
00101   DBG("Pong");
00102   //do
00103   //{
00104     ret = m_sock.recvfrom( &inEndpoint, (char*)&pkt, sizeof(NTPPacket) ); //FIXME need a DNS Resolver to actually compare the incoming address with the DNS name
00105     if(ret < 0)
00106     {
00107       ERR("Could not receive packet (%d)", ret);
00108       m_sock.close();
00109       return NTP_CONN;
00110     }
00111   //} while( strcmp(outEndpoint.get_ip_address(), inEndpoint.get_ip_address()) != 0 );
00112 
00113   if(ret < sizeof(NTPPacket)) //TODO: Accept chunks
00114   {
00115     ERR("Receive packet size does not match");
00116     m_sock.close();
00117     return NTP_PRTCL;
00118   }
00119 
00120   if( pkt.stratum == 0)  //Kiss of death message : Not good !
00121   {
00122     ERR("Kissed to death!");
00123     m_sock.close();
00124     return NTP_PRTCL;
00125   }
00126 
00127   //Correct Endianness
00128   pkt.refTm_s = ntohl( pkt.refTm_s );
00129   pkt.refTm_f = ntohl( pkt.refTm_f );
00130   pkt.origTm_s = ntohl( pkt.origTm_s );
00131   pkt.origTm_f = ntohl( pkt.origTm_f );
00132   pkt.rxTm_s = ntohl( pkt.rxTm_s );
00133   pkt.rxTm_f = ntohl( pkt.rxTm_f );
00134   pkt.txTm_s = ntohl( pkt.txTm_s );
00135   pkt.txTm_f = ntohl( pkt.txTm_f );
00136 
00137   //Compute offset, see RFC 4330 p.13
00138   uint32_t destTm_s = (NTP_TIMESTAMP_DELTA + time(NULL));
00139   int64_t offset = ( (int64_t)( pkt.rxTm_s - pkt.origTm_s ) + (int64_t) ( pkt.txTm_s - destTm_s ) ) / 2; //Avoid overflow
00140   DBG("Sent @%ul", pkt.txTm_s);
00141   DBG("Offset: %lld", offset);
00142   //Set time accordingly
00143   set_time( time(NULL) + offset );
00144 
00145 #ifdef __DEBUG__
00146   ctTime = time(NULL);
00147   DBG("Time is now (UTC): %s", ctime(&ctTime));
00148 #endif
00149 
00150   m_sock.close();
00151 
00152   return NTP_OK;
00153 }
00154