refclock_sock.c

/*
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
 * Copyright (C) Miroslav Lichvar  2009
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 **********************************************************************

  =======================================================================

  Unix domain socket refclock driver.

  */

#include "config.h"

#include "sysincl.h"

#include "refclock.h"
#include "logging.h"
#include "util.h"
#include "sched.h"
#include "socket.h"

#define SOCK_MAGIC 0x534f434b

struct sock_sample {
  /* Time of the measurement (system time) */
  struct timeval tv;

  /* Offset between the true time and the system time (in seconds) */
  double offset;

  /* Non-zero if the sample is from a PPS signal, i.e. another source
     is needed to obtain seconds */
  int pulse;

  /* 0 - normal, 1 - insert leap second, 2 - delete leap second */
  int leap;

  /* Padding, ignored */
  int _pad;

  /* Protocol identifier (0x534f434b) */
  int magic;
};

static void read_sample(int sockfd, int event, void *anything)
{
  struct timespec sys_ts, ref_ts;
  struct sock_sample sample;
  RCL_Instance instance;
  int s;

  instance = (RCL_Instance)anything;

  s = recv(sockfd, &sample, sizeof (sample), 0);

  if (s < 0) {
    DEBUG_LOG("Could not read SOCK sample : %s", strerror(errno));
    return;
  }

  if (s != sizeof (sample)) {
    DEBUG_LOG("Unexpected length of SOCK sample : %d != %ld",
              s, (long)sizeof (sample));
    return;
  }

  if (sample.magic != SOCK_MAGIC) {
    DEBUG_LOG("Unexpected magic number in SOCK sample : %x != %x",
              (unsigned int)sample.magic, (unsigned int)SOCK_MAGIC);
    return;
  }

  UTI_TimevalToTimespec(&sample.tv, &sys_ts);
  UTI_NormaliseTimespec(&sys_ts);

  if (!UTI_IsTimeOffsetSane(&sys_ts, sample.offset))
    return;

  UTI_AddDoubleToTimespec(&sys_ts, sample.offset, &ref_ts);

  if (sample.pulse) {
    RCL_AddPulse(instance, &sys_ts, sample.offset);
  } else {
    RCL_AddSample(instance, &sys_ts, &ref_ts, sample.leap);
  }
}

static int sock_initialise(RCL_Instance instance)
{
  int sockfd;
  char *path;

  RCL_CheckDriverOptions(instance, NULL);

  path = RCL_GetDriverParameter(instance);
 
  sockfd = SCK_OpenUnixDatagramSocket(NULL, path, 0);
  if (sockfd < 0)
    LOG_FATAL("Could not open socket %s", path);

  RCL_SetDriverData(instance, (void *)(long)sockfd);
  SCH_AddFileHandler(sockfd, SCH_FILE_INPUT, read_sample, instance);
  return 1;
}

static void sock_finalise(RCL_Instance instance)
{
  int sockfd;

  sockfd = (long)RCL_GetDriverData(instance);
  SCH_RemoveFileHandler(sockfd);
  SCK_RemoveSocket(sockfd);
  SCK_CloseSocket(sockfd);
}

RefclockDriver RCL_SOCK_driver = {
  sock_initialise,
  sock_finalise,
  NULL
};