Diff: NTPClient.cpp

Revision:

0:537dcd4ff837

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/NTPClient.cpp	Fri Oct 23 14:52:54 2015 +0000
@@ -0,0 +1,164 @@
+/* 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 "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() : m_sock()
+{
+
+
+}
+
+NTPResult NTPClient::setTime(const char* host, uint16_t port, uint32_t timeout)
+{
+#ifdef __DEBUG__
+  time_t ctTime;
+  ctTime = time(NULL);
+  DBG("Time is set to (UTC): %s", ctime(&ctTime));
+#endif
+
+  //Create & bind socket
+  DBG("Binding socket");
+  m_sock.bind(0); //Bind to a random port
+  
+  m_sock.set_blocking(false, timeout); //Set not blocking
+
+  struct NTPPacket pkt;
+
+  //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
+
+  pkt.rootDelay = 0; //Or this one
+  pkt.rootDispersion = 0; //Or that one
+  pkt.refId = 0; //...
+
+  pkt.refTm_s = 0;
+  pkt.origTm_s = 0;
+  pkt.rxTm_s = 0;
+  pkt.txTm_s = htonl( NTP_TIMESTAMP_DELTA + time(NULL) ); //WARN: We are in LE format, network byte order is BE
+
+  pkt.refTm_f = pkt.origTm_f = pkt.rxTm_f = pkt.txTm_f = 0;
+
+  Endpoint outEndpoint;
+  
+  if( outEndpoint.set_address(host, port) < 0)
+  {
+    m_sock.close();
+    return NTP_DNS;
+  }
+  
+  //Set timeout, non-blocking and wait using select
+  int ret = m_sock.sendTo( outEndpoint, (char*)&pkt, sizeof(NTPPacket) );
+  if (ret < 0 )
+  {
+    ERR("Could not send packet");
+    m_sock.close();
+    return NTP_CONN;
+  }
+
+  //Read response
+  Endpoint inEndpoint;
+  // Set the inEndpoint address property
+  inEndpoint.set_address(outEndpoint.get_address(), 0);
+  DBG("Pong");
+  do
+  {
+    ret = m_sock.receiveFrom( inEndpoint, (char*)&pkt, sizeof(NTPPacket) ); //FIXME need a DNS Resolver to actually compare the incoming address with the DNS name
+    if(ret < 0)
+    {
+      ERR("Could not receive packet");
+      m_sock.close();
+      return NTP_CONN;
+    }
+  } while( strcmp(outEndpoint.get_address(), inEndpoint.get_address()) != 0 );
+
+  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 );
+
+  //Compute offset, see RFC 4330 p.13
+  uint32_t destTm_s = (NTP_TIMESTAMP_DELTA + time(NULL));
+  int64_t offset = ( (int64_t)( pkt.rxTm_s - pkt.origTm_s ) + (int64_t) ( pkt.txTm_s - destTm_s ) ) / 2; //Avoid overflow
+  DBG("Sent @%ul", pkt.txTm_s);
+  DBG("Offset: %lld", offset);
+  //Set time accordingly
+  set_time( time(NULL) + offset );
+
+#ifdef __DEBUG__
+  ctTime = time(NULL);
+  DBG("Time is now (UTC): %s", ctime(&ctTime));
+#endif
+
+  m_sock.close();
+
+  return NTP_OK;
+}
+