1 /* #pragma ident "@(#)auth_time.c 1.4 92/11/10 SMI" */ 2 3 /* 4 * auth_time.c 5 * 6 * This module contains the private function __rpc_get_time_offset() 7 * which will return the difference in seconds between the local system's 8 * notion of time and a remote server's notion of time. This must be 9 * possible without calling any functions that may invoke the name 10 * service. (netdir_getbyxxx, getXbyY, etc). The function is used in the 11 * synchronize call of the authdes code to synchronize clocks between 12 * NIS+ clients and their servers. 13 * 14 * Note to minimize the amount of duplicate code, portions of the 15 * synchronize() function were folded into this code, and the synchronize 16 * call becomes simply a wrapper around this function. Further, if this 17 * function is called with a timehost it *DOES* recurse to the name 18 * server so don't use it in that mode if you are doing name service code. 19 * 20 * Copyright (c) 1992 Sun Microsystems Inc. 21 * All rights reserved. 22 * 23 * Side effects : 24 * When called a client handle to a RPCBIND process is created 25 * and destroyed. Two strings "netid" and "uaddr" are malloc'd 26 * and returned. The SIGALRM processing is modified only if 27 * needed to deal with TCP connections. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include "namespace.h" 34 #include <stdio.h> 35 #include <syslog.h> 36 #include <string.h> 37 #include <stdlib.h> 38 #include <unistd.h> 39 #include <netdb.h> 40 #include <sys/signal.h> 41 #include <sys/errno.h> 42 #include <sys/socket.h> 43 #include <netinet/in.h> 44 #include <arpa/inet.h> 45 #include <rpc/rpc.h> 46 #include <rpc/rpc_com.h> 47 #include <rpc/rpcb_prot.h> 48 #undef NIS 49 #include <rpcsvc/nis.h> 50 #include "un-namespace.h" 51 52 extern int _rpc_dtablesize( void ); 53 54 #ifdef TESTING 55 #define msg(x) printf("ERROR: %s\n", x) 56 /* #define msg(x) syslog(LOG_ERR, "%s", x) */ 57 #else 58 #define msg(x) 59 #endif 60 61 static int saw_alarm = 0; 62 63 static void 64 alarm_hndler(s) 65 int s; 66 { 67 saw_alarm = 1; 68 return; 69 } 70 71 /* 72 * The internet time server defines the epoch to be Jan 1, 1900 73 * whereas UNIX defines it to be Jan 1, 1970. To adjust the result 74 * from internet time-service time, into UNIX time we subtract the 75 * following offset : 76 */ 77 #define NYEARS (1970 - 1900) 78 #define TOFFSET ((u_long)60*60*24*(365*NYEARS + (NYEARS/4))) 79 80 81 /* 82 * Stolen from rpc.nisd: 83 * Turn a 'universal address' into a struct sockaddr_in. 84 * Bletch. 85 */ 86 static int uaddr_to_sockaddr(uaddr, sin) 87 #ifdef foo 88 endpoint *endpt; 89 #endif 90 char *uaddr; 91 struct sockaddr_in *sin; 92 { 93 unsigned char p_bytes[2]; 94 int i; 95 unsigned long a[6]; 96 97 i = sscanf(uaddr, "%lu.%lu.%lu.%lu.%lu.%lu", &a[0], &a[1], &a[2], 98 &a[3], &a[4], &a[5]); 99 100 if (i < 6) 101 return(1); 102 103 for (i = 0; i < 4; i++) 104 sin->sin_addr.s_addr |= (a[i] & 0x000000FF) << (8 * i); 105 106 p_bytes[0] = (unsigned char)a[4] & 0x000000FF; 107 p_bytes[1] = (unsigned char)a[5] & 0x000000FF; 108 109 sin->sin_family = AF_INET; /* always */ 110 bcopy((char *)&p_bytes, (char *)&sin->sin_port, 2); 111 112 return (0); 113 } 114 115 /* 116 * free_eps() 117 * 118 * Free the strings that were strduped into the eps structure. 119 */ 120 static void 121 free_eps(eps, num) 122 endpoint eps[]; 123 int num; 124 { 125 int i; 126 127 for (i = 0; i < num; i++) { 128 free(eps[i].uaddr); 129 free(eps[i].proto); 130 free(eps[i].family); 131 } 132 return; 133 } 134 135 /* 136 * get_server() 137 * 138 * This function constructs a nis_server structure description for the 139 * indicated hostname. 140 * 141 * NOTE: There is a chance we may end up recursing here due to the 142 * fact that gethostbyname() could do an NIS search. Ideally, the 143 * NIS+ server will call __rpc_get_time_offset() with the nis_server 144 * structure already populated. 145 */ 146 static nis_server * 147 get_server(sin, host, srv, eps, maxep) 148 struct sockaddr_in *sin; 149 char *host; /* name of the time host */ 150 nis_server *srv; /* nis_server struct to use. */ 151 endpoint eps[]; /* array of endpoints */ 152 int maxep; /* max array size */ 153 { 154 char hname[256]; 155 int num_ep = 0, i; 156 struct hostent *he; 157 struct hostent dummy; 158 char *ptr[2]; 159 endpoint *ep; 160 161 if (host == NULL && sin == NULL) 162 return (NULL); 163 164 if (sin == NULL) { 165 he = gethostbyname(host); 166 if (he == NULL) 167 return(NULL); 168 } else { 169 he = &dummy; 170 ptr[0] = (char *)&sin->sin_addr.s_addr; 171 ptr[1] = NULL; 172 dummy.h_addr_list = ptr; 173 } 174 175 /* 176 * This is lame. We go around once for TCP, then again 177 * for UDP. 178 */ 179 for (i = 0, ep = eps; (he->h_addr_list[i] != NULL) && (num_ep < maxep); 180 i++, ep++, num_ep++) { 181 struct in_addr *a; 182 183 a = (struct in_addr *)he->h_addr_list[i]; 184 snprintf(hname, sizeof(hname), "%s.0.111", inet_ntoa(*a)); 185 ep->uaddr = strdup(hname); 186 ep->family = strdup("inet"); 187 ep->proto = strdup("tcp"); 188 if (ep->uaddr == NULL || ep->family == NULL || ep->proto == NULL) { 189 free_eps(eps, num_ep + 1); 190 return (NULL); 191 } 192 } 193 194 for (i = 0; (he->h_addr_list[i] != NULL) && (num_ep < maxep); 195 i++, ep++, num_ep++) { 196 struct in_addr *a; 197 198 a = (struct in_addr *)he->h_addr_list[i]; 199 snprintf(hname, sizeof(hname), "%s.0.111", inet_ntoa(*a)); 200 ep->uaddr = strdup(hname); 201 ep->family = strdup("inet"); 202 ep->proto = strdup("udp"); 203 if (ep->uaddr == NULL || ep->family == NULL || ep->proto == NULL) { 204 free_eps(eps, num_ep + 1); 205 return (NULL); 206 } 207 } 208 209 srv->name = (nis_name) host; 210 srv->ep.ep_len = num_ep; 211 srv->ep.ep_val = eps; 212 srv->key_type = NIS_PK_NONE; 213 srv->pkey.n_bytes = NULL; 214 srv->pkey.n_len = 0; 215 return (srv); 216 } 217 218 /* 219 * __rpc_get_time_offset() 220 * 221 * This function uses a nis_server structure to contact the a remote 222 * machine (as named in that structure) and returns the offset in time 223 * between that machine and this one. This offset is returned in seconds 224 * and may be positive or negative. 225 * 226 * The first time through, a lot of fiddling is done with the netconfig 227 * stuff to find a suitable transport. The function is very aggressive 228 * about choosing UDP or at worst TCP if it can. This is because 229 * those transports support both the RCPBIND call and the internet 230 * time service. 231 * 232 * Once through, *uaddr is set to the universal address of 233 * the machine and *netid is set to the local netid for the transport 234 * that uaddr goes with. On the second call, the netconfig stuff 235 * is skipped and the uaddr/netid pair are used to fetch the netconfig 236 * structure and to then contact the machine for the time. 237 * 238 * td = "server" - "client" 239 */ 240 int 241 __rpc_get_time_offset(td, srv, thost, uaddr, netid) 242 struct timeval *td; /* Time difference */ 243 nis_server *srv; /* NIS Server description */ 244 char *thost; /* if no server, this is the timehost */ 245 char **uaddr; /* known universal address */ 246 struct sockaddr_in *netid; /* known network identifier */ 247 { 248 CLIENT *clnt; /* Client handle */ 249 endpoint *ep, /* useful endpoints */ 250 *useep = NULL; /* endpoint of xp */ 251 char *useua = NULL; /* uaddr of selected xp */ 252 int epl, i; /* counters */ 253 enum clnt_stat status; /* result of clnt_call */ 254 u_long thetime, delta; 255 int needfree = 0; 256 struct timeval tv; 257 int time_valid; 258 int udp_ep = -1, tcp_ep = -1; 259 int a1, a2, a3, a4; 260 char ut[64], ipuaddr[64]; 261 endpoint teps[32]; 262 nis_server tsrv; 263 void (*oldsig)() = NULL; /* old alarm handler */ 264 struct sockaddr_in sin; 265 socklen_t len; 266 int s = RPC_ANYSOCK; 267 int type = 0; 268 269 td->tv_sec = 0; 270 td->tv_usec = 0; 271 272 /* 273 * First check to see if we need to find and address for this 274 * server. 275 */ 276 if (*uaddr == NULL) { 277 if ((srv != NULL) && (thost != NULL)) { 278 msg("both timehost and srv pointer used!"); 279 return (0); 280 } 281 if (! srv) { 282 srv = get_server(netid, thost, &tsrv, teps, 32); 283 if (srv == NULL) { 284 msg("unable to contruct server data."); 285 return (0); 286 } 287 needfree = 1; /* need to free data in endpoints */ 288 } 289 290 ep = srv->ep.ep_val; 291 epl = srv->ep.ep_len; 292 293 /* Identify the TCP and UDP endpoints */ 294 for (i = 0; 295 (i < epl) && ((udp_ep == -1) || (tcp_ep == -1)); i++) { 296 if (strcasecmp(ep[i].proto, "udp") == 0) 297 udp_ep = i; 298 if (strcasecmp(ep[i].proto, "tcp") == 0) 299 tcp_ep = i; 300 } 301 302 /* Check to see if it is UDP or TCP */ 303 if (tcp_ep > -1) { 304 useep = &ep[tcp_ep]; 305 useua = ep[tcp_ep].uaddr; 306 type = SOCK_STREAM; 307 } else if (udp_ep > -1) { 308 useep = &ep[udp_ep]; 309 useua = ep[udp_ep].uaddr; 310 type = SOCK_DGRAM; 311 } 312 313 if (useep == NULL) { 314 msg("no acceptable transport endpoints."); 315 if (needfree) 316 free_eps(teps, tsrv.ep.ep_len); 317 return (0); 318 } 319 } 320 321 /* 322 * Create a sockaddr from the uaddr. 323 */ 324 if (*uaddr != NULL) 325 useua = *uaddr; 326 327 /* Fixup test for NIS+ */ 328 sscanf(useua, "%d.%d.%d.%d.", &a1, &a2, &a3, &a4); 329 sprintf(ipuaddr, "%d.%d.%d.%d.0.111", a1, a2, a3, a4); 330 useua = &ipuaddr[0]; 331 332 bzero((char *)&sin, sizeof(sin)); 333 if (uaddr_to_sockaddr(useua, &sin)) { 334 msg("unable to translate uaddr to sockaddr."); 335 if (needfree) 336 free_eps(teps, tsrv.ep.ep_len); 337 return (0); 338 } 339 340 /* 341 * Create the client handle to rpcbind. Note we always try 342 * version 3 since that is the earliest version that supports 343 * the RPCB_GETTIME call. Also it is the version that comes 344 * standard with SVR4. Since most everyone supports TCP/IP 345 * we could consider trying the rtime call first. 346 */ 347 clnt = clnttcp_create(&sin, RPCBPROG, RPCBVERS, &s, 0, 0); 348 if (clnt == NULL) { 349 msg("unable to create client handle to rpcbind."); 350 if (needfree) 351 free_eps(teps, tsrv.ep.ep_len); 352 return (0); 353 } 354 355 tv.tv_sec = 5; 356 tv.tv_usec = 0; 357 time_valid = 0; 358 status = clnt_call(clnt, RPCBPROC_GETTIME, (xdrproc_t)xdr_void, NULL, 359 (xdrproc_t)xdr_u_long, &thetime, tv); 360 /* 361 * The only error we check for is anything but success. In 362 * fact we could have seen PROGMISMATCH if talking to a 4.1 363 * machine (pmap v2) or TIMEDOUT if the net was busy. 364 */ 365 if (status == RPC_SUCCESS) 366 time_valid = 1; 367 else { 368 int save; 369 370 /* Blow away possible stale CLNT handle. */ 371 if (clnt != NULL) { 372 clnt_destroy(clnt); 373 clnt = NULL; 374 } 375 376 /* 377 * Convert PMAP address into timeservice address 378 * We take advantage of the fact that we "know" what 379 * the universal address looks like for inet transports. 380 * 381 * We also know that the internet timeservice is always 382 * listening on port 37. 383 */ 384 sscanf(useua, "%d.%d.%d.%d.", &a1, &a2, &a3, &a4); 385 sprintf(ut, "%d.%d.%d.%d.0.37", a1, a2, a3, a4); 386 387 if (uaddr_to_sockaddr(ut, &sin)) { 388 msg("cannot convert timeservice uaddr to sockaddr."); 389 goto error; 390 } 391 392 s = _socket(AF_INET, type, 0); 393 if (s == -1) { 394 msg("unable to open fd to network."); 395 goto error; 396 } 397 398 /* 399 * Now depending on whether or not we're talking to 400 * UDP we set a timeout or not. 401 */ 402 if (type == SOCK_DGRAM) { 403 struct timeval timeout = { 20, 0 }; 404 struct sockaddr_in from; 405 fd_set readfds; 406 int res; 407 408 if (_sendto(s, &thetime, sizeof(thetime), 0, 409 (struct sockaddr *)&sin, sizeof(sin)) == -1) { 410 msg("udp : sendto failed."); 411 goto error; 412 } 413 do { 414 FD_ZERO(&readfds); 415 FD_SET(s, &readfds); 416 res = _select(_rpc_dtablesize(), &readfds, 417 (fd_set *)NULL, (fd_set *)NULL, &timeout); 418 } while (res < 0 && errno == EINTR); 419 if (res <= 0) 420 goto error; 421 len = sizeof(from); 422 res = _recvfrom(s, (char *)&thetime, sizeof(thetime), 0, 423 (struct sockaddr *)&from, &len); 424 if (res == -1) { 425 msg("recvfrom failed on udp transport."); 426 goto error; 427 } 428 time_valid = 1; 429 } else { 430 int res; 431 432 oldsig = (void (*)())signal(SIGALRM, alarm_hndler); 433 saw_alarm = 0; /* global tracking the alarm */ 434 alarm(20); /* only wait 20 seconds */ 435 res = _connect(s, (struct sockaddr *)&sin, sizeof(sin)); 436 if (res == -1) { 437 msg("failed to connect to tcp endpoint."); 438 goto error; 439 } 440 if (saw_alarm) { 441 msg("alarm caught it, must be unreachable."); 442 goto error; 443 } 444 res = _read(s, (char *)&thetime, sizeof(thetime)); 445 if (res != sizeof(thetime)) { 446 if (saw_alarm) 447 msg("timed out TCP call."); 448 else 449 msg("wrong size of results returned"); 450 451 goto error; 452 } 453 time_valid = 1; 454 } 455 save = errno; 456 (void)_close(s); 457 errno = save; 458 s = RPC_ANYSOCK; 459 460 if (time_valid) { 461 thetime = ntohl(thetime); 462 thetime = thetime - TOFFSET; /* adjust to UNIX time */ 463 } else 464 thetime = 0; 465 } 466 467 gettimeofday(&tv, 0); 468 469 error: 470 /* 471 * clean up our allocated data structures. 472 */ 473 474 if (s != RPC_ANYSOCK) 475 (void)_close(s); 476 477 if (clnt != NULL) 478 clnt_destroy(clnt); 479 480 alarm(0); /* reset that alarm if its outstanding */ 481 if (oldsig) { 482 signal(SIGALRM, oldsig); 483 } 484 485 /* 486 * note, don't free uaddr strings until after we've made a 487 * copy of them. 488 */ 489 if (time_valid) { 490 if (*uaddr == NULL) 491 *uaddr = strdup(useua); 492 493 /* Round to the nearest second */ 494 tv.tv_sec += (tv.tv_sec > 500000) ? 1 : 0; 495 delta = (thetime > tv.tv_sec) ? thetime - tv.tv_sec : 496 tv.tv_sec - thetime; 497 td->tv_sec = (thetime < tv.tv_sec) ? - delta : delta; 498 td->tv_usec = 0; 499 } else { 500 msg("unable to get the server's time."); 501 } 502 503 if (needfree) 504 free_eps(teps, tsrv.ep.ep_len); 505 506 return (time_valid); 507 } 508