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