NTP Client Library

Files at this revision

API Documentation at this revision

Comitter:
donatien
Date:
Fri May 25 13:48:49 2012 +0000
Commit message:
Initial Hg Commit

Changed in this revision

NTPClient.cpp Show annotated file Show diff for this revision Revisions of this file
NTPClient.h Show annotated file Show diff for this revision Revisions of this file
diff -r 000000000000 -r 04a82df0f587 NTPClient.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/NTPClient.cpp	Fri May 25 13:48:49 2012 +0000
@@ -0,0 +1,202 @@
+/* NTPClient.cpp */
+/*
+Copyright (C) 2012 ARM Limited.
+
+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.
+*/
+
+#define __DEBUG__ 4 //Maximum verbosity
+#ifndef __MODULE__
+#define __MODULE__ "NTPClient.cpp"
+#endif
+
+#include "core/fwk.h"
+
+#include "NTPClient.h"
+
+#include "mbed.h" //time() and set_time()
+
+#define NTP_PORT 123
+#define NTP_CLIENT_PORT 0 //Random port
+#define NTP_REQUEST_TIMEOUT 15000
+#define NTP_TIMESTAMP_DELTA 2208988800ull //Diff btw a UNIX timestamp (Starting Jan, 1st 1970) and a NTP timestamp (Starting Jan, 1st 1900)
+
+NTPClient::NTPClient()
+{
+
+
+}
+
+int NTPClient::setTime(const char* host, uint16_t port, uint32_t timeout)
+{
+  struct sockaddr_in serverAddr;
+
+  std::memset(&serverAddr, 0, sizeof(struct sockaddr_in));
+
+#if __DEBUG__ >= 3
+  time_t ctTime;
+  ctTime = time(NULL);
+  INFO("Time is set to (UTC): %s", ctime(&ctTime));
+#endif
+
+  //Resolve DNS if needed
+  if(serverAddr.sin_addr.s_addr == 0)
+  {
+    DBG("Resolving DNS address or populate hard-coded IP address");
+    struct hostent *server = socket::gethostbyname(host);
+    if(server == NULL)
+    {
+      return NET_NOTFOUND; //Fail
+    }
+    memcpy((char*)&serverAddr.sin_addr.s_addr, (char*)server->h_addr_list[0], server->h_length);
+  }
+
+  serverAddr.sin_family = AF_INET;
+  serverAddr.sin_port = htons(port);
+
+  //Now create & bind socket
+  DBG("Creating socket");
+  int sock  = socket::socket(AF_INET, SOCK_DGRAM, 0); //UDP socket
+  if (sock < 0)
+  {
+    ERR("Could not create socket");
+    return NET_OOM;
+  }
+  DBG("Handle is %d",sock);
+
+  //Create local address
+  struct sockaddr_in localhostAddr;
+
+  std::memset(&localhostAddr, 0, sizeof(struct sockaddr_in));
+
+  localhostAddr.sin_family = AF_INET;
+  localhostAddr.sin_port = htons(NTP_CLIENT_PORT); //Random port
+  localhostAddr.sin_addr.s_addr = htonl(INADDR_ANY); //Any local address
+
+  if ( socket::bind( sock, (struct sockaddr*)&localhostAddr, sizeof(localhostAddr)) < 0 ) //Listen on local port
+  {
+    ERR("Could not bind socket");
+    socket::close(sock);
+    return NET_OOM;
+  }
+
+  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;
+
+  //Set timeout, non-blocking and wait using select
+  if( socket::sendto( sock, (void*)&pkt, sizeof(NTPPacket), 0, (struct sockaddr*)&serverAddr, sizeof(serverAddr) ) < 0 )
+  {
+    ERR("Could not send packet");
+    socket::close(sock);
+    return NET_CONN;
+  }
+
+  //Wait for socket to be readable
+  //Creating FS set
+  fd_set socksSet;
+  FD_ZERO(&socksSet);
+  FD_SET(sock, &socksSet);
+  struct timeval t_val;
+  t_val.tv_sec = timeout / 1000;
+  t_val.tv_usec = (timeout - (t_val.tv_sec * 1000)) * 1000;
+  int ret = socket::select(FD_SETSIZE, &socksSet, NULL, NULL, &t_val);
+  if(ret <= 0 || !FD_ISSET(sock, &socksSet))
+  {
+    ERR("Timeout while waiting for answer");
+    socket::close(sock);
+    return NET_TIMEOUT; //Timeout
+  }
+
+  //Read response
+  DBG("Pong");
+  struct sockaddr_in respAddr;
+  socklen_t respAddrLen = sizeof(respAddr);
+  do
+  {
+    ret = socket::recvfrom( sock, (void*)&pkt, sizeof(NTPPacket), 0, (struct sockaddr*)&respAddr, &respAddrLen);
+    if(ret < 0)
+    {
+      ERR("Could not receive packet");
+      socket::close(sock);
+      return NET_CONN;
+    }
+  } while( respAddr.sin_addr.s_addr != serverAddr.sin_addr.s_addr);
+
+  if(ret < sizeof(NTPPacket)) //TODO: Accept chunks
+  {
+    ERR("Receive packet size does not match");
+    socket::close(sock);
+    return NET_PROTOCOL;
+  }
+
+  if( pkt.stratum == 0)  //Kiss of death message : Not good !
+  {
+    ERR("Kissed to death!");
+    socket::close(sock);
+    return NTP_PORT;
+  }
+
+  //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: %ul", offset);
+  //Set time accordingly
+  set_time( time(NULL) + offset );
+
+#if __DEBUG__ >= 3
+  ctTime = time(NULL);
+  INFO("Time is now (UTC): %s", ctime(&ctTime));
+#endif
+
+  socket::close(sock);
+
+  return OK;
+}
+
diff -r 000000000000 -r 04a82df0f587 NTPClient.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/NTPClient.h	Fri May 25 13:48:49 2012 +0000
@@ -0,0 +1,86 @@
+/* NTPClient.h */
+/*
+Copyright (C) 2012 ARM Limited.
+
+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 "core/fwk.h"
+
+#ifndef NTPCLIENT_H_
+#define NTPCLIENT_H_
+
+#define NTP_DEFAULT_PORT 123
+#define NTP_DEFAULT_TIMEOUT 4000
+
+#include "api/socket.h"
+
+/** NTP Client to update the mbed's RTC using a remote time server
+*
+*/
+class NTPClient
+{
+public:
+  /**
+  Instantiate the NTP client
+  */
+  NTPClient();
+
+  /**Get current time (blocking)
+  Update the time using the server host
+  Blocks until completion
+  @param host NTP server IPv4 address or hostname (will be resolved via DNS)
+  @param port port to use; defaults to 123
+  @param timeout waiting timeout in ms (osWaitForever for blocking function, not recommended)
+  @return 0 on success, NET error code (<0) on failure
+  */
+  int setTime(const char* host, uint16_t port = NTP_DEFAULT_PORT, uint32_t timeout = NTP_DEFAULT_TIMEOUT); //Blocking
+
+private:
+  struct NTPPacket //See RFC 4330 for Simple NTP
+  {
+    //WARN: We are in LE! Network is BE!
+    //LSb first
+    unsigned mode : 3;
+    unsigned vn : 3;
+    unsigned li : 2;
+
+    uint8_t stratum;
+    uint8_t poll;
+    uint8_t precision;
+    //32 bits header
+
+    uint32_t rootDelay;
+    uint32_t rootDispersion;
+    uint32_t refId;
+
+    uint32_t refTm_s;
+    uint32_t refTm_f;
+    uint32_t origTm_s;
+    uint32_t origTm_f;
+    uint32_t rxTm_s;
+    uint32_t rxTm_f;
+    uint32_t txTm_s;
+    uint32_t txTm_f;
+  } __attribute__ ((packed));
+
+};
+
+
+#endif /* NTPCLIENT_H_ */