1 /* 2 * auth_time.c 3 * 4 * This module contains the private function __rpc_get_time_offset() 5 * which will return the difference in seconds between the local system's 6 * notion of time and a remote server's notion of time. This must be 7 * possible without calling any functions that may invoke the name 8 * service. (netdir_getbyxxx, getXbyY, etc). The function is used in the 9 * synchronize call of the authdes code to synchronize clocks between 10 * NIS+ clients and their servers. 11 * 12 * Note to minimize the amount of duplicate code, portions of the 13 * synchronize() function were folded into this code, and the synchronize 14 * call becomes simply a wrapper around this function. Further, if this 15 * function is called with a timehost it *DOES* recurse to the name 16 * server so don't use it in that mode if you are doing name service code. 17 * 18 * Copyright (c) 1992 Sun Microsystems Inc. 19 * All rights reserved. 20 * 21 * Side effects : 22 * When called a client handle to a RPCBIND process is created 23 * and destroyed. Two strings "netid" and "uaddr" are malloc'd 24 * and returned. The SIGALRM processing is modified only if 25 * needed to deal with TCP connections. 26 * 27 * @(#)auth_time.c 1.4 92/11/10 SMI 28 * $FreeBSD: src/lib/libc/rpc/auth_time.c,v 1.12 2007/09/20 22:35:24 matteo Exp $ 29 */ 30 31 #include "namespace.h" 32 #include <stdio.h> 33 #include <syslog.h> 34 #include <string.h> 35 #include <stdlib.h> 36 #include <unistd.h> 37 #include <netdb.h> 38 #include <sys/signal.h> 39 #include <sys/errno.h> 40 #include <sys/socket.h> 41 #include <netinet/in.h> 42 #include <arpa/inet.h> 43 #include <rpc/rpc.h> 44 #include <rpc/rpc_com.h> 45 #include <rpc/rpcb_prot.h> 46 #undef NIS 47 #include <rpcsvc/nis.h> 48 #include "un-namespace.h" 49 50 int __rpc_get_time_offset(struct timeval *, nis_server *, char *, char **, 51 struct sockaddr_in *); 52 53 extern int _rpc_dtablesize(void); 54 55 #ifdef TESTING 56 #define msg(x) printf("ERROR: %s\n", x) 57 /* #define msg(x) syslog(LOG_ERR, "%s", x) */ 58 #else 59 #define msg(x) 60 #endif 61 62 static int saw_alarm = 0; 63 64 static void 65 alarm_hndler(int s __unused) 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 87 uaddr_to_sockaddr(char *uaddr, struct sockaddr_in *sin) 88 { 89 unsigned char p_bytes[2]; 90 int i; 91 unsigned long a[6]; 92 93 i = sscanf(uaddr, "%lu.%lu.%lu.%lu.%lu.%lu", &a[0], &a[1], &a[2], 94 &a[3], &a[4], &a[5]); 95 96 if (i < 6) 97 return(1); 98 99 for (i = 0; i < 4; i++) 100 sin->sin_addr.s_addr |= (a[i] & 0x000000FF) << (8 * i); 101 102 p_bytes[0] = (unsigned char)a[4] & 0x000000FF; 103 p_bytes[1] = (unsigned char)a[5] & 0x000000FF; 104 105 sin->sin_family = AF_INET; /* always */ 106 bcopy((char *)&p_bytes, (char *)&sin->sin_port, 2); 107 108 return (0); 109 } 110 111 /* 112 * free_eps() 113 * 114 * Free the strings that were strduped into the eps structure. 115 */ 116 static void 117 free_eps(endpoint eps[], int num) 118 { 119 int i; 120 121 for (i = 0; i < num; i++) { 122 free(eps[i].uaddr); 123 free(eps[i].proto); 124 free(eps[i].family); 125 } 126 return; 127 } 128 129 /* 130 * get_server() 131 * 132 * This function constructs a nis_server structure description for the 133 * indicated hostname. 134 * 135 * NOTE: There is a chance we may end up recursing here due to the 136 * fact that gethostbyname() could do an NIS search. Ideally, the 137 * NIS+ server will call __rpc_get_time_offset() with the nis_server 138 * structure already populated. 139 */ 140 static nis_server * 141 get_server(struct sockaddr_in *sin, 142 char *host, /* name of the time host */ 143 nis_server *srv, /* nis_server struct to use. */ 144 endpoint eps[], /* array of endpoints */ 145 int maxep) /* max array size */ 146 { 147 char hname[256]; 148 int num_ep = 0, i; 149 struct hostent *he; 150 struct hostent dummy; 151 char *ptr[2]; 152 endpoint *ep; 153 154 if (host == NULL && sin == NULL) 155 return (NULL); 156 157 if (sin == NULL) { 158 he = gethostbyname(host); 159 if (he == NULL) 160 return(NULL); 161 } else { 162 he = &dummy; 163 ptr[0] = (char *)&sin->sin_addr.s_addr; 164 ptr[1] = NULL; 165 dummy.h_addr_list = ptr; 166 } 167 168 /* 169 * This is lame. We go around once for TCP, then again 170 * for UDP. 171 */ 172 for (i = 0, ep = eps; (he->h_addr_list[i] != NULL) && (num_ep < maxep); 173 i++, ep++, num_ep++) { 174 struct in_addr *a; 175 176 a = (struct in_addr *)he->h_addr_list[i]; 177 snprintf(hname, sizeof(hname), "%s.0.111", inet_ntoa(*a)); 178 ep->uaddr = strdup(hname); 179 ep->family = strdup("inet"); 180 ep->proto = strdup("tcp"); 181 if (ep->uaddr == NULL || ep->family == NULL || ep->proto == NULL) { 182 free_eps(eps, num_ep + 1); 183 return (NULL); 184 } 185 } 186 187 for (i = 0; (he->h_addr_list[i] != NULL) && (num_ep < maxep); 188 i++, ep++, num_ep++) { 189 struct in_addr *a; 190 191 a = (struct in_addr *)he->h_addr_list[i]; 192 snprintf(hname, sizeof(hname), "%s.0.111", inet_ntoa(*a)); 193 ep->uaddr = strdup(hname); 194 ep->family = strdup("inet"); 195 ep->proto = strdup("udp"); 196 if (ep->uaddr == NULL || ep->family == NULL || ep->proto == NULL) { 197 free_eps(eps, num_ep + 1); 198 return (NULL); 199 } 200 } 201 202 srv->name = (nis_name) host; 203 srv->ep.ep_len = num_ep; 204 srv->ep.ep_val = eps; 205 srv->key_type = NIS_PK_NONE; 206 srv->pkey.n_bytes = NULL; 207 srv->pkey.n_len = 0; 208 return (srv); 209 } 210 211 /* 212 * __rpc_get_time_offset() 213 * 214 * This function uses a nis_server structure to contact the a remote 215 * machine (as named in that structure) and returns the offset in time 216 * between that machine and this one. This offset is returned in seconds 217 * and may be positive or negative. 218 * 219 * The first time through, a lot of fiddling is done with the netconfig 220 * stuff to find a suitable transport. The function is very aggressive 221 * about choosing UDP or at worst TCP if it can. This is because 222 * those transports support both the RCPBIND call and the internet 223 * time service. 224 * 225 * Once through, *uaddr is set to the universal address of 226 * the machine and *netid is set to the local netid for the transport 227 * that uaddr goes with. On the second call, the netconfig stuff 228 * is skipped and the uaddr/netid pair are used to fetch the netconfig 229 * structure and to then contact the machine for the time. 230 * 231 * td = "server" - "client" 232 */ 233 int 234 __rpc_get_time_offset(struct timeval *td, /* Time difference */ 235 nis_server *srv, /* NIS Server description */ 236 char *thost, /* if no server, this is the timehost */ 237 char **uaddr, /* known universal address */ 238 struct sockaddr_in *netid)/* known network identifier */ 239 { 240 CLIENT *clnt; /* Client handle */ 241 endpoint *ep, /* useful endpoints */ 242 *useep = NULL; /* endpoint of xp */ 243 char *useua = NULL; /* uaddr of selected xp */ 244 int epl, i; /* counters */ 245 enum clnt_stat status; /* result of clnt_call */ 246 u_long thetime, delta; 247 int needfree = 0; 248 struct timeval tv; 249 int time_valid; 250 int udp_ep = -1, tcp_ep = -1; 251 int a1, a2, a3, a4; 252 char ut[64], ipuaddr[64]; 253 endpoint teps[32]; 254 nis_server tsrv; 255 sig_t oldsig = NULL; /* old alarm handler */ 256 struct sockaddr_in sin; 257 socklen_t len; 258 int s = RPC_ANYSOCK; 259 int type = 0; 260 261 td->tv_sec = 0; 262 td->tv_usec = 0; 263 264 /* 265 * First check to see if we need to find and address for this 266 * server. 267 */ 268 if (*uaddr == NULL) { 269 if ((srv != NULL) && (thost != NULL)) { 270 msg("both timehost and srv pointer used!"); 271 return (0); 272 } 273 if (! srv) { 274 srv = get_server(netid, thost, &tsrv, teps, 32); 275 if (srv == NULL) { 276 msg("unable to contruct server data."); 277 return (0); 278 } 279 needfree = 1; /* need to free data in endpoints */ 280 } 281 282 ep = srv->ep.ep_val; 283 epl = srv->ep.ep_len; 284 285 /* Identify the TCP and UDP endpoints */ 286 for (i = 0; 287 (i < epl) && ((udp_ep == -1) || (tcp_ep == -1)); i++) { 288 if (strcasecmp(ep[i].proto, "udp") == 0) 289 udp_ep = i; 290 if (strcasecmp(ep[i].proto, "tcp") == 0) 291 tcp_ep = i; 292 } 293 294 /* Check to see if it is UDP or TCP */ 295 if (tcp_ep > -1) { 296 useep = &ep[tcp_ep]; 297 useua = ep[tcp_ep].uaddr; 298 type = SOCK_STREAM; 299 } else if (udp_ep > -1) { 300 useep = &ep[udp_ep]; 301 useua = ep[udp_ep].uaddr; 302 type = SOCK_DGRAM; 303 } 304 305 if (useep == NULL) { 306 msg("no acceptable transport endpoints."); 307 if (needfree) 308 free_eps(teps, tsrv.ep.ep_len); 309 return (0); 310 } 311 } 312 313 /* 314 * Create a sockaddr from the uaddr. 315 */ 316 if (*uaddr != NULL) 317 useua = *uaddr; 318 319 /* Fixup test for NIS+ */ 320 sscanf(useua, "%d.%d.%d.%d.", &a1, &a2, &a3, &a4); 321 sprintf(ipuaddr, "%d.%d.%d.%d.0.111", a1, a2, a3, a4); 322 useua = &ipuaddr[0]; 323 324 bzero((char *)&sin, sizeof(sin)); 325 if (uaddr_to_sockaddr(useua, &sin)) { 326 msg("unable to translate uaddr to sockaddr."); 327 if (needfree) 328 free_eps(teps, tsrv.ep.ep_len); 329 return (0); 330 } 331 332 /* 333 * Create the client handle to rpcbind. Note we always try 334 * version 3 since that is the earliest version that supports 335 * the RPCB_GETTIME call. Also it is the version that comes 336 * standard with SVR4. Since most everyone supports TCP/IP 337 * we could consider trying the rtime call first. 338 */ 339 clnt = clnttcp_create(&sin, RPCBPROG, RPCBVERS, &s, 0, 0); 340 if (clnt == NULL) { 341 msg("unable to create client handle to rpcbind."); 342 if (needfree) 343 free_eps(teps, tsrv.ep.ep_len); 344 return (0); 345 } 346 347 tv.tv_sec = 5; 348 tv.tv_usec = 0; 349 time_valid = 0; 350 status = clnt_call(clnt, RPCBPROC_GETTIME, (xdrproc_t)xdr_void, NULL, 351 (xdrproc_t)xdr_u_long, &thetime, tv); 352 /* 353 * The only error we check for is anything but success. In 354 * fact we could have seen PROGMISMATCH if talking to a 4.1 355 * machine (pmap v2) or TIMEDOUT if the net was busy. 356 */ 357 if (status == RPC_SUCCESS) 358 time_valid = 1; 359 else { 360 int save; 361 362 /* Blow away possible stale CLNT handle. */ 363 if (clnt != NULL) { 364 clnt_destroy(clnt); 365 clnt = NULL; 366 } 367 368 /* 369 * Convert PMAP address into timeservice address 370 * We take advantage of the fact that we "know" what 371 * the universal address looks like for inet transports. 372 * 373 * We also know that the internet timeservice is always 374 * listening on port 37. 375 */ 376 sscanf(useua, "%d.%d.%d.%d.", &a1, &a2, &a3, &a4); 377 sprintf(ut, "%d.%d.%d.%d.0.37", a1, a2, a3, a4); 378 379 if (uaddr_to_sockaddr(ut, &sin)) { 380 msg("cannot convert timeservice uaddr to sockaddr."); 381 goto error; 382 } 383 384 s = _socket(AF_INET, type, 0); 385 if (s == -1) { 386 msg("unable to open fd to network."); 387 goto error; 388 } 389 390 /* 391 * Now depending on whether or not we're talking to 392 * UDP we set a timeout or not. 393 */ 394 if (type == SOCK_DGRAM) { 395 struct timeval timeout = { 20, 0 }; 396 struct sockaddr_in from; 397 fd_set readfds; 398 int res; 399 400 if (_sendto(s, &thetime, sizeof(thetime), 0, 401 (struct sockaddr *)&sin, sizeof(sin)) == -1) { 402 msg("udp : sendto failed."); 403 goto error; 404 } 405 do { 406 FD_ZERO(&readfds); 407 FD_SET(s, &readfds); 408 res = _select(_rpc_dtablesize(), &readfds, 409 NULL, NULL, &timeout); 410 } while (res < 0 && errno == EINTR); 411 if (res <= 0) 412 goto error; 413 len = sizeof(from); 414 res = _recvfrom(s, (char *)&thetime, sizeof(thetime), 0, 415 (struct sockaddr *)&from, &len); 416 if (res == -1) { 417 msg("recvfrom failed on udp transport."); 418 goto error; 419 } 420 time_valid = 1; 421 } else { 422 int res; 423 424 oldsig = signal(SIGALRM, alarm_hndler); 425 saw_alarm = 0; /* global tracking the alarm */ 426 alarm(20); /* only wait 20 seconds */ 427 res = _connect(s, (struct sockaddr *)&sin, sizeof(sin)); 428 if (res == -1) { 429 msg("failed to connect to tcp endpoint."); 430 goto error; 431 } 432 if (saw_alarm) { 433 msg("alarm caught it, must be unreachable."); 434 goto error; 435 } 436 res = _read(s, (char *)&thetime, sizeof(thetime)); 437 if (res != sizeof(thetime)) { 438 if (saw_alarm) { 439 msg("timed out TCP call."); 440 } else { 441 msg("wrong size of results returned"); 442 } 443 444 goto error; 445 } 446 time_valid = 1; 447 } 448 save = errno; 449 _close(s); 450 errno = save; 451 s = RPC_ANYSOCK; 452 453 if (time_valid) { 454 thetime = ntohl(thetime); 455 thetime = thetime - TOFFSET; /* adjust to UNIX time */ 456 } else 457 thetime = 0; 458 } 459 460 gettimeofday(&tv, 0); 461 462 error: 463 /* 464 * clean up our allocated data structures. 465 */ 466 467 if (s != RPC_ANYSOCK) 468 _close(s); 469 470 if (clnt != NULL) 471 clnt_destroy(clnt); 472 473 alarm(0); /* reset that alarm if its outstanding */ 474 if (oldsig) { 475 signal(SIGALRM, oldsig); 476 } 477 478 /* 479 * note, don't free uaddr strings until after we've made a 480 * copy of them. 481 */ 482 if (time_valid) { 483 if (*uaddr == NULL) 484 *uaddr = strdup(useua); 485 486 /* Round to the nearest second */ 487 tv.tv_sec += (tv.tv_sec > 500000) ? 1 : 0; 488 delta = (thetime > tv.tv_sec) ? thetime - tv.tv_sec : 489 tv.tv_sec - thetime; 490 td->tv_sec = (thetime < tv.tv_sec) ? - delta : delta; 491 td->tv_usec = 0; 492 } else { 493 msg("unable to get the server's time."); 494 } 495 496 if (needfree) 497 free_eps(teps, tsrv.ep.ep_len); 498 499 return (time_valid); 500 } 501