1 /* $OpenBSD: client.c,v 1.84 2009/03/04 19:17:36 stevesk 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 tos = IPTOS_LOWDELAY; 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->query->fd == -1) { 138 struct sockaddr *sa = (struct sockaddr *)&p->addr->ss; 139 140 if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 141 0)) == -1) 142 fatal("client_query socket"); 143 if (connect(p->query->fd, sa, SA_LEN(sa)) == -1) { 144 if (errno == ECONNREFUSED || errno == ENETUNREACH || 145 errno == EHOSTUNREACH || errno == EADDRNOTAVAIL) { 146 client_nextaddr(p); 147 set_next(p, MAX(SETTIME_TIMEOUT, 148 scale_interval(INTERVAL_QUERY_AGGRESSIVE))); 149 return (-1); 150 } else 151 fatal("client_query connect"); 152 } 153 if (p->addr->ss.ss_family == AF_INET && setsockopt(p->query->fd, 154 IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1) 155 log_warn("setsockopt IPTOS_LOWDELAY"); 156 } 157 158 /* 159 * Send out a random 64-bit number as our transmit time. The NTP 160 * server will copy said number into the originate field on the 161 * response that it sends us. This is totally legal per the SNTP spec. 162 * 163 * The impact of this is two fold: we no longer send out the current 164 * system time for the world to see (which may aid an attacker), and 165 * it gives us a (not very secure) way of knowing that we're not 166 * getting spoofed by an attacker that can't capture our traffic 167 * but can spoof packets from the NTP server we're communicating with. 168 * 169 * Save the real transmit timestamp locally. 170 */ 171 172 p->query->msg.xmttime.int_partl = arc4random(); 173 p->query->msg.xmttime.fractionl = arc4random(); 174 p->query->xmttime = gettime_corrected(); 175 176 if (ntp_sendmsg(p->query->fd, NULL, &p->query->msg, 177 NTP_MSGSIZE_NOAUTH, 0) == -1) { 178 p->senderrors++; 179 set_next(p, INTERVAL_QUERY_PATHETIC); 180 p->trustlevel = TRUSTLEVEL_PATHETIC; 181 return (-1); 182 } 183 184 p->senderrors = 0; 185 p->state = STATE_QUERY_SENT; 186 set_deadline(p, QUERYTIME_MAX); 187 188 return (0); 189 } 190 191 int 192 client_dispatch(struct ntp_peer *p, u_int8_t settime) 193 { 194 char buf[NTP_MSGSIZE]; 195 ssize_t size; 196 struct ntp_msg msg; 197 double T1, T2, T3, T4; 198 time_t interval; 199 200 if ((size = recvfrom(p->query->fd, &buf, sizeof(buf), 0, 201 NULL, NULL)) == -1) { 202 if (errno == EHOSTUNREACH || errno == EHOSTDOWN || 203 errno == ENETUNREACH || errno == ENETDOWN || 204 errno == ECONNREFUSED || errno == EADDRNOTAVAIL) { 205 client_log_error(p, "recvfrom", errno); 206 set_next(p, error_interval()); 207 return (0); 208 } else 209 fatal("recvfrom"); 210 } 211 212 T4 = gettime_corrected(); 213 214 ntp_getmsg((struct sockaddr *)&p->addr->ss, buf, size, &msg); 215 216 if (msg.orgtime.int_partl != p->query->msg.xmttime.int_partl || 217 msg.orgtime.fractionl != p->query->msg.xmttime.fractionl) 218 return (0); 219 220 if ((msg.status & LI_ALARM) == LI_ALARM || msg.stratum == 0 || 221 msg.stratum > NTP_MAXSTRATUM) { 222 char s[16]; 223 224 if ((msg.status & LI_ALARM) == LI_ALARM) { 225 strlcpy(s, "alarm", sizeof(s)); 226 } else if (msg.stratum == 0) { 227 /* Kiss-o'-Death (KoD) packet */ 228 strlcpy(s, "KoD", sizeof(s)); 229 } else if (msg.stratum > NTP_MAXSTRATUM) { 230 snprintf(s, sizeof(s), "stratum %d", msg.stratum); 231 } 232 interval = error_interval(); 233 set_next(p, interval); 234 log_info("reply from %s: not synced (%s), next query %ds", 235 log_sockaddr((struct sockaddr *)&p->addr->ss), s, 236 interval); 237 return (0); 238 } 239 240 /* 241 * From RFC 2030 (with a correction to the delay math): 242 * 243 * Timestamp Name ID When Generated 244 * ------------------------------------------------------------ 245 * Originate Timestamp T1 time request sent by client 246 * Receive Timestamp T2 time request received by server 247 * Transmit Timestamp T3 time reply sent by server 248 * Destination Timestamp T4 time reply received by client 249 * 250 * The roundtrip delay d and local clock offset t are defined as 251 * 252 * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2. 253 */ 254 255 T1 = p->query->xmttime; 256 T2 = lfp_to_d(msg.rectime); 257 T3 = lfp_to_d(msg.xmttime); 258 259 p->reply[p->shift].offset = ((T2 - T1) + (T3 - T4)) / 2; 260 p->reply[p->shift].delay = (T4 - T1) - (T3 - T2); 261 if (p->reply[p->shift].delay < 0) { 262 interval = error_interval(); 263 set_next(p, interval); 264 log_info("reply from %s: negative delay %fs, " 265 "next query %ds", 266 log_sockaddr((struct sockaddr *)&p->addr->ss), 267 p->reply[p->shift].delay, interval); 268 return (0); 269 } 270 p->reply[p->shift].error = (T2 - T1) - (T3 - T4); 271 p->reply[p->shift].rcvd = getmonotime(); 272 p->reply[p->shift].good = 1; 273 274 p->reply[p->shift].status.leap = (msg.status & LIMASK); 275 p->reply[p->shift].status.precision = msg.precision; 276 p->reply[p->shift].status.rootdelay = sfp_to_d(msg.rootdelay); 277 p->reply[p->shift].status.rootdispersion = sfp_to_d(msg.dispersion); 278 p->reply[p->shift].status.refid = msg.refid; 279 p->reply[p->shift].status.reftime = lfp_to_d(msg.reftime); 280 p->reply[p->shift].status.poll = msg.ppoll; 281 p->reply[p->shift].status.stratum = msg.stratum; 282 283 if (p->addr->ss.ss_family == AF_INET) { 284 p->reply[p->shift].status.send_refid = 285 ((struct sockaddr_in *)&p->addr->ss)->sin_addr.s_addr; 286 } else if (p->addr->ss.ss_family == AF_INET6) { 287 MD5_CTX context; 288 u_int8_t digest[MD5_DIGEST_LENGTH]; 289 290 MD5Init(&context); 291 MD5Update(&context, ((struct sockaddr_in6 *)&p->addr->ss)-> 292 sin6_addr.s6_addr, sizeof(struct in6_addr)); 293 MD5Final(digest, &context); 294 memcpy((char *)&p->reply[p->shift].status.send_refid, digest, 295 sizeof(u_int32_t)); 296 } else 297 p->reply[p->shift].status.send_refid = msg.xmttime.fractionl; 298 299 if (p->trustlevel < TRUSTLEVEL_PATHETIC) 300 interval = scale_interval(INTERVAL_QUERY_PATHETIC); 301 else if (p->trustlevel < TRUSTLEVEL_AGGRESSIVE) 302 interval = scale_interval(INTERVAL_QUERY_AGGRESSIVE); 303 else 304 interval = scale_interval(INTERVAL_QUERY_NORMAL); 305 306 set_next(p, interval); 307 p->state = STATE_REPLY_RECEIVED; 308 309 /* every received reply which we do not discard increases trust */ 310 if (p->trustlevel < TRUSTLEVEL_MAX) { 311 if (p->trustlevel < TRUSTLEVEL_BADPEER && 312 p->trustlevel + 1 >= TRUSTLEVEL_BADPEER) 313 log_info("peer %s now valid", 314 log_sockaddr((struct sockaddr *)&p->addr->ss)); 315 p->trustlevel++; 316 } 317 318 log_debug("reply from %s: offset %f delay %f, " 319 "next query %ds", log_sockaddr((struct sockaddr *)&p->addr->ss), 320 p->reply[p->shift].offset, p->reply[p->shift].delay, interval); 321 322 client_update(p); 323 if (settime) 324 priv_settime(p->reply[p->shift].offset); 325 326 if (++p->shift >= OFFSET_ARRAY_SIZE) 327 p->shift = 0; 328 329 return (0); 330 } 331 332 int 333 client_update(struct ntp_peer *p) 334 { 335 int i, best = 0, good = 0; 336 337 /* 338 * clock filter 339 * find the offset which arrived with the lowest delay 340 * use that as the peer update 341 * invalidate it and all older ones 342 */ 343 344 for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++) 345 if (p->reply[i].good) { 346 good++; 347 best = i; 348 } 349 350 for (; i < OFFSET_ARRAY_SIZE; i++) 351 if (p->reply[i].good) { 352 good++; 353 if (p->reply[i].delay < p->reply[best].delay) 354 best = i; 355 } 356 357 if (good < 8) 358 return (-1); 359 360 memcpy(&p->update, &p->reply[best], sizeof(p->update)); 361 if (priv_adjtime() == 0) { 362 for (i = 0; i < OFFSET_ARRAY_SIZE; i++) 363 if (p->reply[i].rcvd <= p->reply[best].rcvd) 364 p->reply[i].good = 0; 365 } 366 return (0); 367 } 368 369 void 370 client_log_error(struct ntp_peer *peer, const char *operation, int error) 371 { 372 const char *address; 373 374 address = log_sockaddr((struct sockaddr *)&peer->addr->ss); 375 if (peer->lasterror == error) { 376 log_debug("%s %s: %s", operation, address, strerror(error)); 377 return; 378 } 379 peer->lasterror = error; 380 log_warn("%s %s", operation, address); 381 } 382