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/*
** Zabbix
** Copyright (C) 2001-2021 Zabbix SIA
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** 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.
**/
#include "sysinfo.h"
#include "comms.h"
#include "log.h"
#include "ntp.h"
#include "common.h"
#define NTP_SCALE 4294967296.0 /* 2^32, of course! */
#define NTP_PACKET_SIZE 48 /* without authentication */
#define NTP_OFFSET_ORIGINATE 24 /* offset of originate timestamp */
#define NTP_OFFSET_TRANSMIT 40 /* offset of transmit timestamp */
#define NTP_VERSION 3 /* the current version */
#define NTP_MODE_CLIENT 3 /* NTP client request */
#define NTP_MODE_SERVER 4 /* NTP server response */
typedef struct
{
unsigned char version;
unsigned char mode;
double transmit;
}
ntp_data;
static void make_packet(ntp_data *data)
{
data->version = NTP_VERSION;
data->mode = NTP_MODE_CLIENT;
data->transmit = zbx_current_time();
}
static void pack_ntp(const ntp_data *data, unsigned char *request, int length)
{
/* Pack the essential data into an NTP packet, bypassing struct layout */
/* and endian problems. Note that it ignores fields irrelevant to SNTP. */
int i, k;
double d;
memset(request, 0, length);
request[0] = (data->version << 3) | data->mode;
d = data->transmit / NTP_SCALE;
for (i = 0; i < 8; i++)
{
if ((k = (int)(d *= 256.0)) >= 256)
k = 255;
request[NTP_OFFSET_TRANSMIT + i] = k;
d -= k;
}
}
static int unpack_ntp(ntp_data *data, const unsigned char *request, const unsigned char *response, int length)
{
/* Unpack the essential data from an NTP packet, bypassing struct layout */
/* and endian problems. Note that it ignores fields irrelevant to SNTP. */
int i, ret = FAIL;
double d;
zabbix_log(LOG_LEVEL_DEBUG, "In %s()", __func__);
if (NTP_PACKET_SIZE != length)
{
zabbix_log(LOG_LEVEL_DEBUG, "invalid response size: %d", length);
goto out;
}
if (0 != memcmp(response + NTP_OFFSET_ORIGINATE, request + NTP_OFFSET_TRANSMIT, 8))
{
zabbix_log(LOG_LEVEL_DEBUG, "originate timestamp in the response does not match"
" transmit timestamp in the request: 0x%04x%04x 0x%04x%04x",
*(const unsigned int *)&response[NTP_OFFSET_ORIGINATE],
*(const unsigned int *)&response[NTP_OFFSET_ORIGINATE + 4],
*(const unsigned int *)&request[NTP_OFFSET_TRANSMIT],
*(const unsigned int *)&request[NTP_OFFSET_TRANSMIT + 4]);
goto out;
}
data->version = (response[0] >> 3) & 7;
if (NTP_VERSION != data->version)
{
zabbix_log(LOG_LEVEL_DEBUG, "invalid NTP version in the response: %d", (int)data->version);
goto out;
}
data->mode = response[0] & 7;
if (NTP_MODE_SERVER != data->mode)
{
zabbix_log(LOG_LEVEL_DEBUG, "invalid mode in the response: %d", (int)data->mode);
goto out;
}
if (15 < response[1])
{
zabbix_log(LOG_LEVEL_DEBUG, "invalid stratum in the response: %d", (int)response[1]);
goto out;
}
d = 0.0;
for (i = 0; i < 8; i++)
d = 256.0 * d + response[NTP_OFFSET_TRANSMIT + i];
data->transmit = d / NTP_SCALE;
if (0 == data->transmit)
{
zabbix_log(LOG_LEVEL_DEBUG, "invalid transmit timestamp in the response: " ZBX_FS_DBL, data->transmit);
goto out;
}
ret = SUCCEED;
out:
zabbix_log(LOG_LEVEL_DEBUG, "End of %s():%s", __func__, zbx_result_string(ret));
return ret;
}
int check_ntp(char *host, unsigned short port, int timeout, int *value_int)
{
zbx_socket_t s;
int ret;
char request[NTP_PACKET_SIZE];
ntp_data data;
*value_int = 0;
if (SUCCEED == (ret = zbx_udp_connect(&s, CONFIG_SOURCE_IP, host, port, timeout)))
{
make_packet(&data);
pack_ntp(&data, (unsigned char *)request, sizeof(request));
if (SUCCEED == (ret = zbx_udp_send(&s, request, sizeof(request), timeout)))
{
if (SUCCEED == (ret = zbx_udp_recv(&s, timeout)))
{
*value_int = (SUCCEED == unpack_ntp(&data, (unsigned char *)request,
(unsigned char *)s.buffer, (int)s.read_bytes));
}
}
zbx_udp_close(&s);
}
if (FAIL == ret)
zabbix_log(LOG_LEVEL_DEBUG, "NTP check error: %s", zbx_socket_strerror());
return SYSINFO_RET_OK;
}
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