1 /* $OpenBSD: client.c,v 1.89 2011/09/21 15:41:30 phessler Exp $ */ 2 3 /* 4 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org> 5 * Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org> 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER 16 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING 17 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 #include <sys/param.h> 21 #include <errno.h> 22 #include <md5.h> 23 #include <stdio.h> 24 #include <stdlib.h> 25 #include <string.h> 26 #include <time.h> 27 #include <unistd.h> 28 29 #include "ntpd.h" 30 31 int client_update(struct ntp_peer *); 32 void set_deadline(struct ntp_peer *, time_t); 33 34 void 35 set_next(struct ntp_peer *p, time_t t) 36 { 37 p->next = getmonotime() + t; 38 p->deadline = 0; 39 } 40 41 void 42 set_deadline(struct ntp_peer *p, time_t t) 43 { 44 p->deadline = getmonotime() + t; 45 p->next = 0; 46 } 47 48 int 49 client_peer_init(struct ntp_peer *p) 50 { 51 if ((p->query = calloc(1, sizeof(struct ntp_query))) == NULL) 52 fatal("client_peer_init calloc"); 53 p->query->fd = -1; 54 p->query->msg.status = MODE_CLIENT | (NTP_VERSION << 3); 55 p->state = STATE_NONE; 56 p->shift = 0; 57 p->trustlevel = TRUSTLEVEL_PATHETIC; 58 p->lasterror = 0; 59 p->senderrors = 0; 60 61 return (client_addr_init(p)); 62 } 63 64 int 65 client_addr_init(struct ntp_peer *p) 66 { 67 struct sockaddr_in *sa_in; 68 struct sockaddr_in6 *sa_in6; 69 struct ntp_addr *h; 70 71 for (h = p->addr; h != NULL; h = h->next) { 72 switch (h->ss.ss_family) { 73 case AF_INET: 74 sa_in = (struct sockaddr_in *)&h->ss; 75 if (ntohs(sa_in->sin_port) == 0) 76 sa_in->sin_port = htons(123); 77 p->state = STATE_DNS_DONE; 78 break; 79 case AF_INET6: 80 sa_in6 = (struct sockaddr_in6 *)&h->ss; 81 if (ntohs(sa_in6->sin6_port) == 0) 82 sa_in6->sin6_port = htons(123); 83 p->state = STATE_DNS_DONE; 84 break; 85 default: 86 fatalx("king bula sez: wrong AF in client_addr_init"); 87 /* not reached */ 88 } 89 } 90 91 p->query->fd = -1; 92 set_next(p, 0); 93 94 return (0); 95 } 96 97 int 98 client_nextaddr(struct ntp_peer *p) 99 { 100 if (p->query->fd != -1) { 101 close(p->query->fd); 102 p->query->fd = -1; 103 } 104 105 if (p->state == STATE_DNS_INPROGRESS) 106 return (-1); 107 108 if (p->addr_head.a == NULL) { 109 priv_host_dns(p->addr_head.name, p->id); 110 p->state = STATE_DNS_INPROGRESS; 111 return (-1); 112 } 113 114 if ((p->addr = p->addr->next) == NULL) 115 p->addr = p->addr_head.a; 116 117 p->shift = 0; 118 p->trustlevel = TRUSTLEVEL_PATHETIC; 119 120 return (0); 121 } 122 123 int 124 client_query(struct ntp_peer *p) 125 { 126 int val; 127 128 if (p->addr == NULL && client_nextaddr(p) == -1) { 129 set_next(p, MAX(SETTIME_TIMEOUT, 130 scale_interval(INTERVAL_QUERY_AGGRESSIVE))); 131 return (0); 132 } 133 134 if (p->state < STATE_DNS_DONE || p->addr == NULL) 135 return (-1); 136 137 if (p->addr->ss.ss_family != AF_INET && p->rtable != -1) 138 return (-1); 139 140 if (p->query->fd == -1) { 141 struct sockaddr *sa = (struct sockaddr *)&p->addr->ss; 142 143 if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 144 0)) == -1) 145 fatal("client_query socket"); 146 147 if (p->addr->ss.ss_family == AF_INET && p->rtable != -1 && 148 setsockopt(p->query->fd, IPPROTO_IP, SO_RTABLE, 149 &p->rtable, sizeof(p->rtable)) == -1) 150 fatal("client_query setsockopt SO_RTABLE"); 151 if (connect(p->query->fd, sa, SA_LEN(sa)) == -1) { 152 if (errno == ECONNREFUSED || errno == ENETUNREACH || 153 errno == EHOSTUNREACH || errno == EADDRNOTAVAIL) { 154 client_nextaddr(p); 155 set_next(p, MAX(SETTIME_TIMEOUT, 156 scale_interval(INTERVAL_QUERY_AGGRESSIVE))); 157 return (-1); 158 } else 159 fatal("client_query connect"); 160 } 161 val = IPTOS_LOWDELAY; 162 if (p->addr->ss.ss_family == AF_INET && setsockopt(p->query->fd, 163 IPPROTO_IP, IP_TOS, &val, sizeof(val)) == -1) 164 log_warn("setsockopt IPTOS_LOWDELAY"); 165 val = 1; 166 if (setsockopt(p->query->fd, SOL_SOCKET, SO_TIMESTAMP, 167 &val, sizeof(val)) == -1) 168 fatal("setsockopt SO_TIMESTAMP"); 169 } 170 171 /* 172 * Send out a random 64-bit number as our transmit time. The NTP 173 * server will copy said number into the originate field on the 174 * response that it sends us. This is totally legal per the SNTP spec. 175 * 176 * The impact of this is two fold: we no longer send out the current 177 * system time for the world to see (which may aid an attacker), and 178 * it gives us a (not very secure) way of knowing that we're not 179 * getting spoofed by an attacker that can't capture our traffic 180 * but can spoof packets from the NTP server we're communicating with. 181 * 182 * Save the real transmit timestamp locally. 183 */ 184 185 p->query->msg.xmttime.int_partl = arc4random(); 186 p->query->msg.xmttime.fractionl = arc4random(); 187 p->query->xmttime = gettime_corrected(); 188 189 if (ntp_sendmsg(p->query->fd, NULL, &p->query->msg, 190 NTP_MSGSIZE_NOAUTH, 0) == -1) { 191 p->senderrors++; 192 set_next(p, INTERVAL_QUERY_PATHETIC); 193 p->trustlevel = TRUSTLEVEL_PATHETIC; 194 return (-1); 195 } 196 197 p->senderrors = 0; 198 p->state = STATE_QUERY_SENT; 199 set_deadline(p, QUERYTIME_MAX); 200 201 return (0); 202 } 203 204 int 205 client_dispatch(struct ntp_peer *p, u_int8_t settime) 206 { 207 struct ntp_msg msg; 208 struct msghdr somsg; 209 struct iovec iov[1]; 210 struct timeval tv; 211 char buf[NTP_MSGSIZE]; 212 union { 213 struct cmsghdr hdr; 214 char buf[CMSG_SPACE(sizeof(tv))]; 215 } cmsgbuf; 216 struct cmsghdr *cmsg; 217 ssize_t size; 218 double T1, T2, T3, T4; 219 time_t interval; 220 221 bzero(&somsg, sizeof(somsg)); 222 iov[0].iov_base = buf; 223 iov[0].iov_len = sizeof(buf); 224 somsg.msg_iov = iov; 225 somsg.msg_iovlen = 1; 226 somsg.msg_control = cmsgbuf.buf; 227 somsg.msg_controllen = sizeof(cmsgbuf.buf); 228 229 T4 = getoffset(); 230 if ((size = recvmsg(p->query->fd, &somsg, 0)) == -1) { 231 if (errno == EHOSTUNREACH || errno == EHOSTDOWN || 232 errno == ENETUNREACH || errno == ENETDOWN || 233 errno == ECONNREFUSED || errno == EADDRNOTAVAIL || 234 errno == ENOPROTOOPT || errno == ENOENT) { 235 client_log_error(p, "recvmsg", errno); 236 set_next(p, error_interval()); 237 return (0); 238 } else 239 fatal("recvfrom"); 240 } 241 242 if (somsg.msg_flags & MSG_TRUNC) { 243 client_log_error(p, "recvmsg packet", EMSGSIZE); 244 set_next(p, error_interval()); 245 return (0); 246 } 247 248 if (somsg.msg_flags & MSG_CTRUNC) { 249 client_log_error(p, "recvmsg control data", E2BIG); 250 set_next(p, error_interval()); 251 return (0); 252 } 253 254 if (p->rtable != -1 && 255 setsockopt(p->query->fd, IPPROTO_IP, SO_RTABLE, &p->rtable, 256 sizeof(p->rtable)) == -1) 257 fatal("client_dispatch setsockopt SO_RTABLE"); 258 259 for (cmsg = CMSG_FIRSTHDR(&somsg); cmsg != NULL; 260 cmsg = CMSG_NXTHDR(&somsg, cmsg)) { 261 if (cmsg->cmsg_level == SOL_SOCKET && 262 cmsg->cmsg_type == SCM_TIMESTAMP) { 263 memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv)); 264 T4 += tv.tv_sec + JAN_1970 + 1.0e-6 * tv.tv_usec; 265 break; 266 } 267 } 268 269 if (T4 < JAN_1970) { 270 client_log_error(p, "recvmsg control format", EBADF); 271 set_next(p, error_interval()); 272 return (0); 273 } 274 275 ntp_getmsg((struct sockaddr *)&p->addr->ss, buf, size, &msg); 276 277 if (msg.orgtime.int_partl != p->query->msg.xmttime.int_partl || 278 msg.orgtime.fractionl != p->query->msg.xmttime.fractionl) 279 return (0); 280 281 if ((msg.status & LI_ALARM) == LI_ALARM || msg.stratum == 0 || 282 msg.stratum > NTP_MAXSTRATUM) { 283 char s[16]; 284 285 if ((msg.status & LI_ALARM) == LI_ALARM) { 286 strlcpy(s, "alarm", sizeof(s)); 287 } else if (msg.stratum == 0) { 288 /* Kiss-o'-Death (KoD) packet */ 289 strlcpy(s, "KoD", sizeof(s)); 290 } else if (msg.stratum > NTP_MAXSTRATUM) { 291 snprintf(s, sizeof(s), "stratum %d", msg.stratum); 292 } 293 interval = error_interval(); 294 set_next(p, interval); 295 log_info("reply from %s: not synced (%s), next query %ds", 296 log_sockaddr((struct sockaddr *)&p->addr->ss), s, 297 interval); 298 return (0); 299 } 300 301 /* 302 * From RFC 2030 (with a correction to the delay math): 303 * 304 * Timestamp Name ID When Generated 305 * ------------------------------------------------------------ 306 * Originate Timestamp T1 time request sent by client 307 * Receive Timestamp T2 time request received by server 308 * Transmit Timestamp T3 time reply sent by server 309 * Destination Timestamp T4 time reply received by client 310 * 311 * The roundtrip delay d and local clock offset t are defined as 312 * 313 * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2. 314 */ 315 316 T1 = p->query->xmttime; 317 T2 = lfp_to_d(msg.rectime); 318 T3 = lfp_to_d(msg.xmttime); 319 320 /* 321 * XXX workaround: time_t / tv_sec must never wrap. 322 * around 2020 we will need a solution (64bit time_t / tv_sec). 323 * consider every answer with a timestamp beyond january 2030 bogus. 324 */ 325 if (T2 > JAN_2030 || T3 > JAN_2030) { 326 set_next(p, error_interval()); 327 return (0); 328 } 329 330 p->reply[p->shift].offset = ((T2 - T1) + (T3 - T4)) / 2; 331 p->reply[p->shift].delay = (T4 - T1) - (T3 - T2); 332 if (p->reply[p->shift].delay < 0) { 333 interval = error_interval(); 334 set_next(p, interval); 335 log_info("reply from %s: negative delay %fs, " 336 "next query %ds", 337 log_sockaddr((struct sockaddr *)&p->addr->ss), 338 p->reply[p->shift].delay, interval); 339 return (0); 340 } 341 p->reply[p->shift].error = (T2 - T1) - (T3 - T4); 342 p->reply[p->shift].rcvd = getmonotime(); 343 p->reply[p->shift].good = 1; 344 345 p->reply[p->shift].status.leap = (msg.status & LIMASK); 346 p->reply[p->shift].status.precision = msg.precision; 347 p->reply[p->shift].status.rootdelay = sfp_to_d(msg.rootdelay); 348 p->reply[p->shift].status.rootdispersion = sfp_to_d(msg.dispersion); 349 p->reply[p->shift].status.refid = msg.refid; 350 p->reply[p->shift].status.reftime = lfp_to_d(msg.reftime); 351 p->reply[p->shift].status.poll = msg.ppoll; 352 p->reply[p->shift].status.stratum = msg.stratum; 353 354 if (p->addr->ss.ss_family == AF_INET) { 355 p->reply[p->shift].status.send_refid = 356 ((struct sockaddr_in *)&p->addr->ss)->sin_addr.s_addr; 357 } else if (p->addr->ss.ss_family == AF_INET6) { 358 MD5_CTX context; 359 u_int8_t digest[MD5_DIGEST_LENGTH]; 360 361 MD5Init(&context); 362 MD5Update(&context, ((struct sockaddr_in6 *)&p->addr->ss)-> 363 sin6_addr.s6_addr, sizeof(struct in6_addr)); 364 MD5Final(digest, &context); 365 memcpy((char *)&p->reply[p->shift].status.send_refid, digest, 366 sizeof(u_int32_t)); 367 } else 368 p->reply[p->shift].status.send_refid = msg.xmttime.fractionl; 369 370 if (p->trustlevel < TRUSTLEVEL_PATHETIC) 371 interval = scale_interval(INTERVAL_QUERY_PATHETIC); 372 else if (p->trustlevel < TRUSTLEVEL_AGGRESSIVE) 373 interval = scale_interval(INTERVAL_QUERY_AGGRESSIVE); 374 else 375 interval = scale_interval(INTERVAL_QUERY_NORMAL); 376 377 set_next(p, interval); 378 p->state = STATE_REPLY_RECEIVED; 379 380 /* every received reply which we do not discard increases trust */ 381 if (p->trustlevel < TRUSTLEVEL_MAX) { 382 if (p->trustlevel < TRUSTLEVEL_BADPEER && 383 p->trustlevel + 1 >= TRUSTLEVEL_BADPEER) 384 log_info("peer %s now valid", 385 log_sockaddr((struct sockaddr *)&p->addr->ss)); 386 p->trustlevel++; 387 } 388 389 log_debug("reply from %s: offset %f delay %f, " 390 "next query %ds %s", 391 log_sockaddr((struct sockaddr *)&p->addr->ss), 392 p->reply[p->shift].offset, p->reply[p->shift].delay, interval, 393 print_rtable(p->rtable)); 394 395 client_update(p); 396 if (settime) 397 priv_settime(p->reply[p->shift].offset); 398 399 if (++p->shift >= OFFSET_ARRAY_SIZE) 400 p->shift = 0; 401 402 return (0); 403 } 404 405 int 406 client_update(struct ntp_peer *p) 407 { 408 int i, best = 0, good = 0; 409 410 /* 411 * clock filter 412 * find the offset which arrived with the lowest delay 413 * use that as the peer update 414 * invalidate it and all older ones 415 */ 416 417 for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++) 418 if (p->reply[i].good) { 419 good++; 420 best = i; 421 } 422 423 for (; i < OFFSET_ARRAY_SIZE; i++) 424 if (p->reply[i].good) { 425 good++; 426 if (p->reply[i].delay < p->reply[best].delay) 427 best = i; 428 } 429 430 if (good < 8) 431 return (-1); 432 433 memcpy(&p->update, &p->reply[best], sizeof(p->update)); 434 if (priv_adjtime() == 0) { 435 for (i = 0; i < OFFSET_ARRAY_SIZE; i++) 436 if (p->reply[i].rcvd <= p->reply[best].rcvd) 437 p->reply[i].good = 0; 438 } 439 return (0); 440 } 441 442 void 443 client_log_error(struct ntp_peer *peer, const char *operation, int error) 444 { 445 const char *address; 446 447 address = log_sockaddr((struct sockaddr *)&peer->addr->ss); 448 if (peer->lasterror == error) { 449 log_debug("%s %s: %s", operation, address, strerror(error)); 450 return; 451 } 452 peer->lasterror = error; 453 log_warn("%s %s", operation, address); 454 } 455