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
alarm_hndler(int s __unused)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
uaddr_to_sockaddr(char * uaddr,struct sockaddr_in * sin)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
free_eps(endpoint eps[],int num)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 *
get_server(struct sockaddr_in * sin,char * host,nis_server * srv,endpoint eps[],int maxep)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
__rpc_get_time_offset(struct timeval * td,nis_server * srv,char * thost,char ** uaddr,struct sockaddr_in * netid)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