/*****************************************************************************
 *
 * Monitoring check_ntp_time plugin
 *
 * License: GPL
 * Copyright (c) 2006 Sean Finney <seanius@seanius.net>
 * Copyright (c) 2006-2024 Monitoring Plugins Development Team
 *
 * Description:
 *
 * This file contains the check_ntp_time plugin
 *
 * This plugin checks the clock offset between the local host and a
 * remote NTP server. It is independent of any commandline programs or
 * external libraries.
 *
 * If you'd rather want to monitor an NTP server, please use
 * check_ntp_peer.
 *
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 *
 *****************************************************************************/

#include "output.h"
#include "common.h"
#include "netutils.h"
#include "perfdata.h"
#include "utils.h"
#include "states.h"
#include "thresholds.h"
#include "check_ntp_time.d/config.h"
#include <netinet/in.h>
#include <string.h>
#include <sys/socket.h>

static int verbose = 0;

const char *progname = "check_ntp_time";
const char *copyright = "2006-2024";
const char *email = "devel@monitoring-plugins.org";

typedef struct {
	int errorcode;
	check_ntp_time_config config;
} check_ntp_time_config_wrapper;
static check_ntp_time_config_wrapper process_arguments(int /*argc*/, char ** /*argv*/);

static void print_help(void);
void print_usage(void);

/* number of times to perform each request to get a good average. */
#ifndef AVG_NUM
#	define AVG_NUM 4
#endif

/* this structure holds everything in an ntp request/response as per rfc1305 */
typedef struct {
	uint8_t flags;    /* byte with leapindicator,vers,mode. see macros */
	uint8_t stratum;  /* clock stratum */
	int8_t poll;      /* polling interval */
	int8_t precision; /* precision of the local clock */
	int32_t rtdelay;  /* total rt delay, as a fixed point num. see macros */
	uint32_t rtdisp;  /* like above, but for max err to primary src */
	uint32_t refid;   /* ref clock identifier */
	uint64_t refts;   /* reference timestamp.  local time local clock */
	uint64_t origts;  /* time at which request departed client */
	uint64_t rxts;    /* time at which request arrived at server */
	uint64_t txts;    /* time at which request departed server */
} ntp_message;

/* this structure holds data about results from querying offset from a peer */
typedef struct {
	time_t waiting;         /* ts set when we started waiting for a response */
	int num_responses;      /* number of successfully received responses */
	uint8_t stratum;        /* copied verbatim from the ntp_message */
	double rtdelay;         /* converted from the ntp_message */
	double rtdisp;          /* converted from the ntp_message */
	double offset[AVG_NUM]; /* offsets from each response */
	uint8_t flags;          /* byte with leapindicator,vers,mode. see macros */
} ntp_server_results;

/* bits 1,2 are the leap indicator */
#define LI_MASK 0xc0
#define LI(x)   ((x & LI_MASK) >> 6)
#define LI_SET(x, y)                                                                               \
	do {                                                                                           \
		x |= ((y << 6) & LI_MASK);                                                                 \
	} while (0)
/* and these are the values of the leap indicator */
#define LI_NOWARNING  0x00
#define LI_EXTRASEC   0x01
#define LI_MISSINGSEC 0x02
#define LI_ALARM      0x03
/* bits 3,4,5 are the ntp version */
#define VN_MASK 0x38
#define VN(x)   ((x & VN_MASK) >> 3)
#define VN_SET(x, y)                                                                               \
	do {                                                                                           \
		x |= ((y << 3) & VN_MASK);                                                                 \
	} while (0)
#define VN_RESERVED 0x02
/* bits 6,7,8 are the ntp mode */
#define MODE_MASK 0x07
#define MODE(x)   (x & MODE_MASK)
#define MODE_SET(x, y)                                                                             \
	do {                                                                                           \
		x |= (y & MODE_MASK);                                                                      \
	} while (0)
/* here are some values */
#define MODE_CLIENT     0x03
#define MODE_CONTROLMSG 0x06
/* In control message, bits 8-10 are R,E,M bits */
#define REM_MASK  0xe0
#define REM_RESP  0x80
#define REM_ERROR 0x40
#define REM_MORE  0x20
/* In control message, bits 11 - 15 are opcode */
#define OP_MASK 0x1f
#define OP_SET(x, y)                                                                               \
	do {                                                                                           \
		x |= (y & OP_MASK);                                                                        \
	} while (0)
#define OP_READSTAT 0x01
#define OP_READVAR  0x02
/* In peer status bytes, bits 6,7,8 determine clock selection status */
#define PEER_SEL(x)     ((ntohs(x) >> 8) & 0x07)
#define PEER_INCLUDED   0x04
#define PEER_SYNCSOURCE 0x06

/**
 ** a note about the 32-bit "fixed point" numbers:
 **
 they are divided into halves, each being a 16-bit int in network byte order:
 - the first 16 bits are an int on the left side of a decimal point.
 - the second 16 bits represent a fraction n/(2^16)
 likewise for the 64-bit "fixed point" numbers with everything doubled :)
 **/

/* macros to access the left/right 16 bits of a 32-bit ntp "fixed point"
   number.  note that these can be used as lvalues too */
#define L16(x) (((uint16_t *)&x)[0])
#define R16(x) (((uint16_t *)&x)[1])
/* macros to access the left/right 32 bits of a 64-bit ntp "fixed point"
   number.  these too can be used as lvalues */
#define L32(x) (((uint32_t *)&x)[0])
#define R32(x) (((uint32_t *)&x)[1])

/* ntp wants seconds since 1/1/00, epoch is 1/1/70.  this is the difference */
#define EPOCHDIFF 0x83aa7e80UL

/* extract a 32-bit ntp fixed point number into a double */
#define NTP32asDOUBLE(x) (ntohs(L16(x)) + ((double)ntohs(R16(x)) / 65536.0))

/* likewise for a 64-bit ntp fp number */
#define NTP64asDOUBLE(n)                                                                           \
	(double)(((uint64_t)n) ? (ntohl(L32(n)) - EPOCHDIFF) +                                         \
								 (.00000001 * (0.5 + (double)(ntohl(R32(n)) / 42.94967296)))       \
						   : 0)

/* convert a struct timeval to a double */
static double TVasDOUBLE(struct timeval time) {
	return ((double)time.tv_sec + (0.000001 * (double)time.tv_usec));
}

/* convert an ntp 64-bit fp number to a struct timeval */
#define NTP64toTV(n, t)                                                                            \
	do {                                                                                           \
		if (!n)                                                                                    \
			t.tv_sec = t.tv_usec = 0;                                                              \
		else {                                                                                     \
			t.tv_sec = ntohl(L32(n)) - EPOCHDIFF;                                                  \
			t.tv_usec = (int)(0.5 + (double)(ntohl(R32(n)) / 4294.967296));                        \
		}                                                                                          \
	} while (0)

/* convert a struct timeval to an ntp 64-bit fp number */
#define TVtoNTP64(t, n)                                                                            \
	do {                                                                                           \
		if (!t.tv_usec && !t.tv_sec)                                                               \
			n = 0x0UL;                                                                             \
		else {                                                                                     \
			L32(n) = htonl(t.tv_sec + EPOCHDIFF);                                                  \
			R32(n) = htonl((uint64_t)((4294.967296 * t.tv_usec) + .5));                            \
		}                                                                                          \
	} while (0)

/* NTP control message header is 12 bytes, plus any data in the data
 * field, plus null padding to the nearest 32-bit boundary per rfc.
 */
#define SIZEOF_NTPCM(m) (12 + ntohs(m.count) + ((m.count) ? 4 - (ntohs(m.count) % 4) : 0))

/* finally, a little helper or two for debugging: */
#define DBG(x)                                                                                     \
	do {                                                                                           \
		if (verbose > 1) {                                                                         \
			x;                                                                                     \
		}                                                                                          \
	} while (0);
#define PRINTSOCKADDR(x)                                                                           \
	do {                                                                                           \
		printf("%u.%u.%u.%u", (x >> 24) & 0xff, (x >> 16) & 0xff, (x >> 8) & 0xff, x & 0xff);      \
	} while (0);

/* calculate the offset of the local clock */
static inline double calc_offset(const ntp_message *message, const struct timeval *time_value) {
	double client_tx = NTP64asDOUBLE(message->origts);
	double peer_rx = NTP64asDOUBLE(message->rxts);
	double peer_tx = NTP64asDOUBLE(message->txts);
	double client_rx = TVasDOUBLE((*time_value));
	return (((peer_tx - client_rx) + (peer_rx - client_tx)) / 2);
}

/* print out a ntp packet in human readable/debuggable format */
void print_ntp_message(const ntp_message *message) {
	struct timeval ref;
	struct timeval orig;

	NTP64toTV(message->refts, ref);
	NTP64toTV(message->origts, orig);

	printf("packet contents:\n");
	printf("\tflags: 0x%.2x\n", message->flags);
	printf("\t  li=%d (0x%.2x)\n", LI(message->flags), message->flags & LI_MASK);
	printf("\t  vn=%d (0x%.2x)\n", VN(message->flags), message->flags & VN_MASK);
	printf("\t  mode=%d (0x%.2x)\n", MODE(message->flags), message->flags & MODE_MASK);
	printf("\tstratum = %d\n", message->stratum);
	printf("\tpoll = %g\n", pow(2, message->poll));
	printf("\tprecision = %g\n", pow(2, message->precision));
	printf("\trtdelay = %-.16g\n", NTP32asDOUBLE(message->rtdelay));
	printf("\trtdisp = %-.16g\n", NTP32asDOUBLE(message->rtdisp));
	printf("\trefid = %x\n", message->refid);
	printf("\trefts = %-.16g\n", NTP64asDOUBLE(message->refts));
	printf("\torigts = %-.16g\n", NTP64asDOUBLE(message->origts));
	printf("\trxts = %-.16g\n", NTP64asDOUBLE(message->rxts));
	printf("\ttxts = %-.16g\n", NTP64asDOUBLE(message->txts));
}

void setup_request(ntp_message *message) {
	memset(message, 0, sizeof(ntp_message));
	LI_SET(message->flags, LI_ALARM);
	VN_SET(message->flags, 4);
	MODE_SET(message->flags, MODE_CLIENT);
	message->poll = 4;
	message->precision = (int8_t)0xfa;
	L16(message->rtdelay) = htons(1);
	L16(message->rtdisp) = htons(1);

	struct timeval t;
	gettimeofday(&t, NULL);
	TVtoNTP64(t, message->txts);
}

/* select the "best" server from a list of servers, and return its index.
 * this is done by filtering servers based on stratum, dispersion, and
 * finally round-trip delay. */
static int best_offset_server(const ntp_server_results *slist, int nservers) {
	int best_server_index = -1;

	/* for each server */
	for (int cserver = 0; cserver < nservers; cserver++) {
		/* We don't want any servers that fails these tests */
		/* Sort out servers that didn't respond or responede with a 0 stratum;
		 * stratum 0 is for reference clocks so no NTP server should ever report
		 * a stratum 0 */
		if (slist[cserver].stratum == 0) {
			if (verbose) {
				printf("discarding peer %d: stratum=%d\n", cserver, slist[cserver].stratum);
			}
			continue;
		}
		/* Sort out servers with error flags */
		if (LI(slist[cserver].flags) == LI_ALARM) {
			if (verbose) {
				printf("discarding peer %d: flags=%d\n", cserver, LI(slist[cserver].flags));
			}
			continue;
		}

		/* If we don't have a server yet, use the first one */
		if (best_server_index == -1) {
			best_server_index = cserver;
			DBG(printf("using peer %d as our first candidate\n", best_server_index));
			continue;
		}

		/* compare the server to the best one we've seen so far */
		/* does it have an equal or better stratum? */
		DBG(printf("comparing peer %d with peer %d\n", cserver, best_server_index));
		if (slist[cserver].stratum <= slist[best_server_index].stratum) {
			DBG(printf("stratum for peer %d <= peer %d\n", cserver, best_server_index));
			/* does it have an equal or better dispersion? */
			if (slist[cserver].rtdisp <= slist[best_server_index].rtdisp) {
				DBG(printf("dispersion for peer %d <= peer %d\n", cserver, best_server_index));
				/* does it have a better rtdelay? */
				if (slist[cserver].rtdelay < slist[best_server_index].rtdelay) {
					DBG(printf("rtdelay for peer %d < peer %d\n", cserver, best_server_index));
					best_server_index = cserver;
					DBG(printf("peer %d is now our best candidate\n", best_server_index));
				}
			}
		}
	}

	if (best_server_index >= 0) {
		DBG(printf("best server selected: peer %d\n", best_server_index));
		return best_server_index;
	}
	DBG(printf("no peers meeting synchronization criteria :(\n"));
	return -1;
}

/* do everything we need to get the total average offset
 * - we use a certain amount of parallelization with poll() to ensure
 *   we don't waste time sitting around waiting for single packets.
 * - we also "manually" handle resolving host names and connecting, because
 *   we have to do it in a way that our lazy macros don't handle currently :( */
typedef struct {
	mp_state_enum offset_result;
	double offset;
} offset_request_wrapper;
static offset_request_wrapper offset_request(const char *host, const char *port, int time_offset) {
	/* setup hints to only return results from getaddrinfo that we'd like */
	struct addrinfo hints;
	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = address_family;
	hints.ai_protocol = IPPROTO_UDP;
	hints.ai_socktype = SOCK_DGRAM;

	bool is_socket;
	struct addrinfo *addresses = NULL;
	size_t num_hosts = 0;
	if (host[0] == '/') {
		num_hosts = 1;
		is_socket = true;
	} else {
		is_socket = false;

		/* fill in ai with the list of hosts resolved by the host name */
		int ga_result = getaddrinfo(host, port, &hints, &addresses);
		if (ga_result != 0) {
			die(STATE_UNKNOWN, "error getting address for %s: %s\n", host, gai_strerror(ga_result));
		}

		/* count the number of returned hosts, and allocate stuff accordingly */
		for (struct addrinfo *ai_tmp = addresses; ai_tmp != NULL; ai_tmp = ai_tmp->ai_next) {
			num_hosts++;
		}
	}

	ntp_message *req = (ntp_message *)malloc(sizeof(ntp_message) * num_hosts);

	if (req == NULL) {
		die(STATE_UNKNOWN, "can not allocate ntp message array");
	}
	int *socklist = (int *)malloc(sizeof(int) * num_hosts);

	if (socklist == NULL) {
		die(STATE_UNKNOWN, "can not allocate socket array");
	}

	struct pollfd *ufds = (struct pollfd *)malloc(sizeof(struct pollfd) * num_hosts);
	if (ufds == NULL) {
		die(STATE_UNKNOWN, "can not allocate socket array");
	}

	ntp_server_results *servers =
		(ntp_server_results *)malloc(sizeof(ntp_server_results) * num_hosts);
	if (servers == NULL) {
		die(STATE_UNKNOWN, "can not allocate server array");
	}
	memset(servers, 0, sizeof(ntp_server_results) * num_hosts);
	DBG(printf("Found %zu peers to check\n", num_hosts));

	/* setup each socket for writing, and the corresponding struct pollfd */
	if (is_socket) {
		socklist[0] = socket(AF_UNIX, SOCK_STREAM, 0);
		if (socklist[0] == -1) {
			DBG(printf("can't create socket: %s\n", strerror(errno)));
			die(STATE_UNKNOWN, "can not create new socket\n");
		}

		struct sockaddr_un unix_socket = {
			.sun_family = AF_UNIX,
		};

		if (strlen(host) > sizeof(unix_socket.sun_path)) {
			die(STATE_UNKNOWN, "host argument is too long (%lu) for a socket path\n", strlen(host));
		}
		strncpy(unix_socket.sun_path, host, sizeof(unix_socket.sun_path));

		if (connect(socklist[0], &unix_socket, sizeof(unix_socket))) {
			/* don't die here, because it is enough if there is one server
			   answering in time. This also would break for dual ipv4/6 stacked
			   ntp servers when the client only supports on of them.
			 */
			DBG(printf("can't create socket connection on peer %i: %s\n", 0, strerror(errno)));
		} else {
			ufds[0].fd = socklist[0];
			ufds[0].events = POLLIN;
			ufds[0].revents = 0;
		}
	} else {
		struct addrinfo *ai_tmp = addresses;
		for (int i = 0; ai_tmp; i++) {
			socklist[i] = socket(ai_tmp->ai_family, SOCK_DGRAM, IPPROTO_UDP);
			if (socklist[i] == -1) {
				perror(NULL);
				die(STATE_UNKNOWN, "can not create new socket");
			}
			if (connect(socklist[i], ai_tmp->ai_addr, ai_tmp->ai_addrlen)) {
				/* don't die here, because it is enough if there is one server
				   answering in time. This also would break for dual ipv4/6 stacked
				   ntp servers when the client only supports on of them.
				 */
				DBG(printf("can't create socket connection on peer %i: %s\n", i, strerror(errno)));
			} else {
				ufds[i].fd = socklist[i];
				ufds[i].events = POLLIN;
				ufds[i].revents = 0;
			}
			ai_tmp = ai_tmp->ai_next;
		}
	}

	/* now do AVG_NUM checks to each host. We stop before timeout/2 seconds
	 * have passed in order to ensure post-processing and jitter time. */
	time_t start_ts = 0;
	time_t now_time = 0;
	now_time = start_ts = time(NULL);
	size_t servers_completed = 0;
	bool one_read = false;
	while (servers_completed < num_hosts && now_time - start_ts <= socket_timeout / 2) {
		/* loop through each server and find each one which hasn't
		 * been touched in the past second or so and is still lacking
		 * some responses. For each of these servers, send a new request,
		 * and update the "waiting" timestamp with the current time. */
		now_time = time(NULL);

		for (size_t i = 0; i < num_hosts; i++) {
			if (servers[i].waiting < now_time && servers[i].num_responses < AVG_NUM) {
				if (verbose && servers[i].waiting != 0) {
					printf("re-");
				}
				if (verbose) {
					printf("sending request to peer %zu\n", i);
				}
				setup_request(&req[i]);
				write(socklist[i], &req[i], sizeof(ntp_message));
				servers[i].waiting = now_time;
				break;
			}
		}

		/* quickly poll for any sockets with pending data */
		int servers_readable = poll(ufds, num_hosts, 100);
		if (servers_readable == -1) {
			perror("polling ntp sockets");
			die(STATE_UNKNOWN, "communication errors");
		}

		/* read from any sockets with pending data */
		for (size_t i = 0; servers_readable && i < num_hosts; i++) {
			if (ufds[i].revents & POLLIN && servers[i].num_responses < AVG_NUM) {
				if (verbose) {
					printf("response from peer %zu: ", i);
				}

				read(ufds[i].fd, &req[i], sizeof(ntp_message));

				struct timeval recv_time;
				gettimeofday(&recv_time, NULL);
				DBG(print_ntp_message(&req[i]));
				int respnum = servers[i].num_responses++;
				servers[i].offset[respnum] = calc_offset(&req[i], &recv_time) + time_offset;
				if (verbose) {
					printf("offset %.10g\n", servers[i].offset[respnum]);
				}
				servers[i].stratum = req[i].stratum;
				servers[i].rtdisp = NTP32asDOUBLE(req[i].rtdisp);
				servers[i].rtdelay = NTP32asDOUBLE(req[i].rtdelay);
				servers[i].waiting = 0;
				servers[i].flags = req[i].flags;
				servers_readable--;
				one_read = true;
				if (servers[i].num_responses == AVG_NUM) {
					servers_completed++;
				}
			}
		}
		/* lather, rinse, repeat. */
	}

	if (!one_read) {
		die(STATE_CRITICAL, "NTP CRITICAL: No response from NTP server\n");
	}

	offset_request_wrapper result = {
		.offset = 0,
		.offset_result = STATE_UNKNOWN,
	};

	/* now, pick the best server from the list */
	double avg_offset = 0.;
	int best_index = best_offset_server(servers, num_hosts);
	if (best_index < 0) {
		result.offset_result = STATE_UNKNOWN;
	} else {
		result.offset_result = STATE_OK;
		/* finally, calculate the average offset */
		for (int i = 0; i < servers[best_index].num_responses; i++) {
			avg_offset += servers[best_index].offset[i];
		}
		avg_offset /= servers[best_index].num_responses;
	}

	/* cleanup */
	for (size_t j = 0; j < num_hosts; j++) {
		close(socklist[j]);
	}
	free(socklist);
	free(ufds);
	free(servers);
	free(req);
	freeaddrinfo(addresses);

	if (verbose) {
		printf("overall average offset: %.10g\n", avg_offset);
	}

	result.offset = avg_offset;
	return result;
}

static check_ntp_time_config_wrapper process_arguments(int argc, char **argv) {

	enum {
		output_format_index = CHAR_MAX + 1,
	};

	static struct option longopts[] = {{"version", no_argument, 0, 'V'},
									   {"help", no_argument, 0, 'h'},
									   {"verbose", no_argument, 0, 'v'},
									   {"use-ipv4", no_argument, 0, '4'},
									   {"use-ipv6", no_argument, 0, '6'},
									   {"quiet", no_argument, 0, 'q'},
									   {"time-offset", required_argument, 0, 'o'},
									   {"warning", required_argument, 0, 'w'},
									   {"critical", required_argument, 0, 'c'},
									   {"timeout", required_argument, 0, 't'},
									   {"hostname", required_argument, 0, 'H'},
									   {"port", required_argument, 0, 'p'},
									   {"output-format", required_argument, 0, output_format_index},
									   {0, 0, 0, 0}};

	if (argc < 2) {
		usage("\n");
	}

	check_ntp_time_config_wrapper result = {
		.errorcode = OK,
		.config = check_ntp_time_config_init(),
	};

	while (true) {
		int option = 0;
		int option_char = getopt_long(argc, argv, "Vhv46qw:c:t:H:p:o:", longopts, &option);
		if (option_char == -1 || option_char == EOF || option_char == 1) {
			break;
		}

		switch (option_char) {
		case output_format_index: {
			parsed_output_format parser = mp_parse_output_format(optarg);
			if (!parser.parsing_success) {
				printf("Invalid output format: %s\n", optarg);
				exit(STATE_UNKNOWN);
			}

			result.config.output_format_is_set = true;
			result.config.output_format = parser.output_format;
			break;
		}
		case 'h':
			print_help();
			exit(STATE_UNKNOWN);
			break;
		case 'V':
			print_revision(progname, NP_VERSION);
			exit(STATE_UNKNOWN);
			break;
		case 'v':
			verbose++;
			break;
		case 'q':
			result.config.quiet = true;
			break;
		case 'w': {
			mp_range_parsed tmp = mp_parse_range_string(optarg);
			if (tmp.error != MP_PARSING_SUCCESS) {
				die(STATE_UNKNOWN, "failed to parse warning threshold");
			}

			result.config.offset_thresholds =
				mp_thresholds_set_warn(result.config.offset_thresholds, tmp.range);
		} break;
		case 'c': {
			mp_range_parsed tmp = mp_parse_range_string(optarg);
			if (tmp.error != MP_PARSING_SUCCESS) {
				die(STATE_UNKNOWN, "failed to parse crit threshold");
			}

			result.config.offset_thresholds =
				mp_thresholds_set_crit(result.config.offset_thresholds, tmp.range);
		} break;
		case 'H':
			if (!is_host(optarg) && (optarg[0] != '/')) {
				usage2(_("Invalid hostname/address"), optarg);
			}
			result.config.server_address = strdup(optarg);
			break;
		case 'p':
			result.config.port = strdup(optarg);
			break;
		case 't':
			socket_timeout = atoi(optarg);
			break;
		case 'o':
			result.config.time_offset = atoi(optarg);
			break;
		case '4':
			address_family = AF_INET;
			break;
		case '6':
			address_family = AF_INET6;
			break;
		case '?':
			/* print short usage statement if args not parsable */
			usage5();
			break;
		}
	}

	if (result.config.server_address == NULL) {
		usage4(_("Hostname was not supplied"));
	}

	return result;
}

int main(int argc, char *argv[]) {
#ifdef __OpenBSD__
	/* - rpath is required to read --extra-opts (given up later)
	 * - inet is required for sockets
	 * - unix is required for Unix domain sockets
	 * - dns is required for name lookups */
	pledge("stdio rpath inet unix dns", NULL);
#endif // __OpenBSD__

	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);

	/* Parse extra opts if any */
	argv = np_extra_opts(&argc, argv, progname);

	check_ntp_time_config_wrapper tmp_config = process_arguments(argc, argv);

	if (tmp_config.errorcode == ERROR) {
		usage4(_("Could not parse arguments"));
	}

#ifdef __OpenBSD__
	pledge("stdio inet unix dns", NULL);
#endif // __OpenBSD__

	const check_ntp_time_config config = tmp_config.config;

	if (config.output_format_is_set) {
		mp_set_format(config.output_format);
	}

	/* initialize alarm signal handling */
	signal(SIGALRM, socket_timeout_alarm_handler);

	/* set socket timeout */
	alarm(socket_timeout);

	mp_check overall = mp_check_init();

	mp_set_ok_summary(&overall, "NTP time synchronisation seems to be working");

	mp_subcheck sc_offset = mp_subcheck_init();
	offset_request_wrapper offset_result =
		offset_request(config.server_address, config.port, config.time_offset);

	if (offset_result.offset_result == STATE_UNKNOWN) {
		sc_offset =
			mp_set_subcheck_state(sc_offset, (!config.quiet) ? STATE_UNKNOWN : STATE_CRITICAL);
		xasprintf(&sc_offset.output, "Offset unknown");
		mp_add_subcheck_to_check(&overall, sc_offset);
		mp_exit(overall);
	}

	xasprintf(&sc_offset.output, "Offset: %.6fs", offset_result.offset);

	mp_perfdata pd_offset = perfdata_init();
	pd_offset = mp_set_pd_value(pd_offset, fabs(offset_result.offset));
	pd_offset.label = "offset";
	pd_offset.uom = "s";
	pd_offset = mp_pd_set_thresholds(pd_offset, config.offset_thresholds);

	sc_offset = mp_set_subcheck_state(sc_offset, mp_get_pd_status(pd_offset));

	mp_add_perfdata_to_subcheck(&sc_offset, pd_offset);
	mp_add_subcheck_to_check(&overall, sc_offset);

	if (config.server_address != NULL) {
		free(config.server_address);
	}
	mp_exit(overall);
}

void print_help(void) {
	print_revision(progname, NP_VERSION);

	printf("Copyright (c) 2006 Sean Finney\n");
	printf(COPYRIGHT, copyright, email);

	printf("%s\n", _("This plugin checks the clock offset with the ntp server"));

	printf("\n\n");

	print_usage();
	printf(UT_HELP_VRSN);
	printf(UT_EXTRA_OPTS);
	printf(UT_IPv46);
	printf(UT_HOST_PORT, 'p', "123");
	printf(" %s\n", "-q, --quiet");
	printf("    %s\n", _("Returns UNKNOWN instead of CRITICAL if offset cannot be found"));
	printf(" %s\n", "-w, --warning=THRESHOLD");
	printf("    %s\n", _("Offset to result in warning status (seconds)"));
	printf(" %s\n", "-c, --critical=THRESHOLD");
	printf("    %s\n", _("Offset to result in critical status (seconds)"));
	printf(" %s\n", "-o, --time-offset=INTEGER");
	printf("    %s\n", _("Expected offset of the ntp server relative to local server (seconds)"));
	printf(UT_CONN_TIMEOUT, DEFAULT_SOCKET_TIMEOUT);
	printf(UT_VERBOSE);
	printf(UT_OUTPUT_FORMAT);

	printf("\n");
	printf("%s\n", _("This plugin checks the clock offset between the local host and a"));
	printf("%s\n", _("remote NTP server. It is independent of any commandline programs or"));
	printf("%s\n", _("external libraries."));

	printf("\n");
	printf("%s\n", _("Notes:"));
	printf(" %s\n", _("If you'd rather want to monitor an NTP server, please use"));
	printf(" %s\n", _("check_ntp_peer."));
	printf(" %s\n", _("--time-offset is useful for compensating for servers with known"));
	printf(" %s\n", _("and expected clock skew."));
	printf("\n");
	printf(UT_THRESHOLDS_NOTES);

	printf("\n");
	printf("%s\n", _("Examples:"));
	printf("  %s\n", ("./check_ntp_time -H ntpserv -w 0.5 -c 1"));

	printf(UT_SUPPORT);
}

void print_usage(void) {
	printf("%s\n", _("Usage:"));
	printf(" %s -H <host> [-4|-6] [-w <warn>] [-c <crit>] [-v verbose] [-o <time offset>]\n",
		   progname);
}
