/***************************************************************************** * * Monitoring check_ntp_time plugin * * License: GPL * Copyright (c) 2006 Sean Finney * 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 . * * *****************************************************************************/ const char *progname = "check_ntp_time"; const char *copyright = "2006-2024"; const char *email = "devel@monitoring-plugins.org"; #include "common.h" #include "netutils.h" #include "utils.h" static char *server_address = NULL; static char *port = "123"; static int verbose = 0; static bool quiet = false; static char *owarn = "60"; static char *ocrit = "120"; static int time_offset = 0; static int process_arguments(int, char **); static thresholds *offset_thresholds = NULL; 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 /* max size of control message data */ #define MAX_CM_SIZE 468 /* 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 */ #define TVasDOUBLE(x) (double)(x.tv_sec + (0.000001 * x.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 *m, const struct timeval *t) { double client_tx = NTP64asDOUBLE(m->origts); double peer_rx = NTP64asDOUBLE(m->rxts); double peer_tx = NTP64asDOUBLE(m->txts); double client_rx = TVasDOUBLE((*t)); return (.5 * ((peer_tx - client_rx) + (peer_rx - client_tx))); } /* print out a ntp packet in human readable/debuggable format */ void print_ntp_message(const ntp_message *p) { struct timeval ref; struct timeval orig; struct timeval rx; struct timeval tx; NTP64toTV(p->refts, ref); NTP64toTV(p->origts, orig); NTP64toTV(p->rxts, rx); NTP64toTV(p->txts, tx); printf("packet contents:\n"); printf("\tflags: 0x%.2x\n", p->flags); printf("\t li=%d (0x%.2x)\n", LI(p->flags), p->flags & LI_MASK); printf("\t vn=%d (0x%.2x)\n", VN(p->flags), p->flags & VN_MASK); printf("\t mode=%d (0x%.2x)\n", MODE(p->flags), p->flags & MODE_MASK); printf("\tstratum = %d\n", p->stratum); printf("\tpoll = %g\n", pow(2, p->poll)); printf("\tprecision = %g\n", pow(2, p->precision)); printf("\trtdelay = %-.16g\n", NTP32asDOUBLE(p->rtdelay)); printf("\trtdisp = %-.16g\n", NTP32asDOUBLE(p->rtdisp)); printf("\trefid = %x\n", p->refid); printf("\trefts = %-.16g\n", NTP64asDOUBLE(p->refts)); printf("\torigts = %-.16g\n", NTP64asDOUBLE(p->origts)); printf("\trxts = %-.16g\n", NTP64asDOUBLE(p->rxts)); printf("\ttxts = %-.16g\n", NTP64asDOUBLE(p->txts)); } void setup_request(ntp_message *p) { memset(p, 0, sizeof(ntp_message)); LI_SET(p->flags, LI_ALARM); VN_SET(p->flags, 4); MODE_SET(p->flags, MODE_CLIENT); p->poll = 4; p->precision = (int8_t)0xfa; L16(p->rtdelay) = htons(1); L16(p->rtdisp) = htons(1); struct timeval t; gettimeofday(&t, NULL); TVtoNTP64(t, p->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. */ int best_offset_server(const ntp_server_results *slist, int nservers) { int best_server = -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 == -1) { best_server = cserver; DBG(printf("using peer %d as our first candidate\n", best_server)); 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)); if (slist[cserver].stratum <= slist[best_server].stratum) { DBG(printf("stratum for peer %d <= peer %d\n", cserver, best_server)); /* does it have an equal or better dispersion? */ if (slist[cserver].rtdisp <= slist[best_server].rtdisp) { DBG(printf("dispersion for peer %d <= peer %d\n", cserver, best_server)); /* does it have a better rtdelay? */ if (slist[cserver].rtdelay < slist[best_server].rtdelay) { DBG(printf("rtdelay for peer %d < peer %d\n", cserver, best_server)); best_server = cserver; DBG(printf("peer %d is now our best candidate\n", best_server)); } } } } if (best_server >= 0) { DBG(printf("best server selected: peer %d\n", best_server)); return best_server; } 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 :( */ double offset_request(const char *host, int *status) { /* 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; /* fill in ai with the list of hosts resolved by the host name */ struct addrinfo *ai = NULL; int ga_result = getaddrinfo(host, port, &hints, &ai); 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 */ int num_hosts = 0; for (struct addrinfo *ai_tmp = ai; 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 %d peers to check\n", num_hosts)); /* setup each socket for writing, and the corresponding struct pollfd */ struct addrinfo *ai_tmp = ai; 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); int 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 (int 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 %d\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 (int 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 %d: ", 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 == false) { die(STATE_CRITICAL, "NTP CRITICAL: No response from NTP server\n"); } /* 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) { *status = STATE_UNKNOWN; } else { /* 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 (int j = 0; j < num_hosts; j++) { close(socklist[j]); } free(socklist); free(ufds); free(servers); free(req); freeaddrinfo(ai); if (verbose) printf("overall average offset: %.10g\n", avg_offset); return avg_offset; } int process_arguments(int argc, char **argv) { 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", optional_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'}, {0, 0, 0, 0}}; if (argc < 2) usage("\n"); 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 'h': print_help(); exit(STATE_UNKNOWN); break; case 'V': print_revision(progname, NP_VERSION); exit(STATE_UNKNOWN); break; case 'v': verbose++; break; case 'q': quiet = true; break; case 'w': owarn = optarg; break; case 'c': ocrit = optarg; break; case 'H': if (!is_host(optarg)) usage2(_("Invalid hostname/address"), optarg); server_address = strdup(optarg); break; case 'p': port = strdup(optarg); break; case 't': socket_timeout = atoi(optarg); break; case 'o': time_offset = atoi(optarg); break; case '4': address_family = AF_INET; break; case '6': #ifdef USE_IPV6 address_family = AF_INET6; #else usage4(_("IPv6 support not available")); #endif break; case '?': /* print short usage statement if args not parsable */ usage5(); break; } } if (server_address == NULL) { usage4(_("Hostname was not supplied")); } return 0; } char *perfd_offset(double offset) { return fperfdata("offset", offset, "s", true, offset_thresholds->warning->end, true, offset_thresholds->critical->end, false, 0, false, 0); } int main(int argc, char *argv[]) { setlocale(LC_ALL, ""); bindtextdomain(PACKAGE, LOCALEDIR); textdomain(PACKAGE); /* Parse extra opts if any */ argv = np_extra_opts(&argc, argv, progname); if (process_arguments(argc, argv) == ERROR) usage4(_("Could not parse arguments")); set_thresholds(&offset_thresholds, owarn, ocrit); /* initialize alarm signal handling */ signal(SIGALRM, socket_timeout_alarm_handler); /* set socket timeout */ alarm(socket_timeout); int offset_result = STATE_OK; int result = STATE_OK; double offset = offset_request(server_address, &offset_result); if (offset_result == STATE_UNKNOWN) { result = ((!quiet) ? STATE_UNKNOWN : STATE_CRITICAL); } else { result = get_status(fabs(offset), offset_thresholds); } char *result_line; switch (result) { case STATE_CRITICAL: xasprintf(&result_line, _("NTP CRITICAL:")); break; case STATE_WARNING: xasprintf(&result_line, _("NTP WARNING:")); break; case STATE_OK: xasprintf(&result_line, _("NTP OK:")); break; default: xasprintf(&result_line, _("NTP UNKNOWN:")); break; } char *perfdata_line; if (offset_result == STATE_UNKNOWN) { xasprintf(&result_line, "%s %s", result_line, _("Offset unknown")); xasprintf(&perfdata_line, ""); } else { xasprintf(&result_line, "%s %s %.10g secs", result_line, _("Offset"), offset); xasprintf(&perfdata_line, "%s", perfd_offset(offset)); } printf("%s|%s\n", result_line, perfdata_line); if (server_address != NULL) free(server_address); return result; } 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("\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 [-4|-6] [-w ] [-c ] [-v verbose] [-o