1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1995, 1996
5 * Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by Bill Paul.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36 /*
37 * Do standard and reverse DNS lookups using the resolver library.
38 * Take care of all the dirty work here so the main program only has to
39 * pass us a pointer to an array of characters.
40 *
41 * We have to use direct resolver calls here otherwise the YP server
42 * could end up looping by calling itself over and over again until
43 * it disappeared up its own belly button.
44 */
45
46 #include <sys/param.h>
47 #include <sys/socket.h>
48 #include <sys/time.h>
49 #include <sys/fcntl.h>
50 #include <sys/queue.h>
51 #include <netinet/in.h>
52 #include <arpa/inet.h>
53 #include <arpa/nameser.h>
54
55 #include <ctype.h>
56 #include <errno.h>
57 #include <netdb.h>
58 #include <stdio.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <resolv.h>
62 #include <unistd.h>
63
64 #include <rpcsvc/yp.h>
65 #include "yp_extern.h"
66
67 static char *
parse(struct hostent * hp)68 parse(struct hostent *hp)
69 {
70 static char result[MAXHOSTNAMELEN * 2];
71 int i;
72 size_t len;
73 char addr[46];
74
75 if (hp == NULL)
76 return(NULL);
77
78 if (inet_ntop(hp->h_addrtype, hp->h_addr, addr, sizeof(addr)) == NULL)
79 return(NULL);
80
81 len = strlen(addr) + 1 + strlen(hp->h_name);
82 for (i = 0; hp->h_aliases[i]; i++)
83 len += strlen(hp->h_aliases[i]) + 1;
84 len++;
85
86 if (len > sizeof(result))
87 return(NULL);
88
89 bzero(result, sizeof(result));
90 snprintf(result, sizeof(result), "%s %s", addr, hp->h_name);
91 for (i = 0; hp->h_aliases[i]; i++) {
92 strcat(result, " ");
93 strcat(result, hp->h_aliases[i]);
94 }
95
96 return ((char *)&result);
97 }
98
99 #define MAXPACKET (64*1024)
100 #define DEF_TTL 50
101
102 #define BY_DNS_ID 1
103 #define BY_RPC_XID 2
104
105 extern struct hostent *__dns_getanswer(char *, int, char *, int);
106
107 static TAILQ_HEAD(dns_qhead, circleq_dnsentry) qhead;
108
109 struct circleq_dnsentry {
110 SVCXPRT *xprt;
111 unsigned long xid;
112 struct sockaddr_in client_addr;
113 unsigned long ypvers;
114 unsigned long id;
115 unsigned long ttl;
116 unsigned long type;
117 unsigned short prot_type;
118 char **domain;
119 char *name;
120 int addrtype;
121 int addrlen;
122 uint32_t addr[4]; /* IPv4 or IPv6 */
123 TAILQ_ENTRY(circleq_dnsentry) links;
124 };
125
126 static int pending = 0;
127
128 int
yp_init_resolver(void)129 yp_init_resolver(void)
130 {
131 TAILQ_INIT(&qhead);
132 if (!(_res.options & RES_INIT) && res_init() == -1) {
133 yp_error("res_init failed");
134 return(1);
135 }
136 if ((resfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
137 yp_error("couldn't create socket");
138 return(1);
139 }
140 if (fcntl(resfd, F_SETFL, O_NONBLOCK) == -1) {
141 yp_error("couldn't make resolver socket non-blocking");
142 return(1);
143 }
144 return(0);
145 }
146
147 static struct
yp_malloc_dnsent(void)148 circleq_dnsentry *yp_malloc_dnsent(void)
149 {
150 register struct circleq_dnsentry *q;
151
152 q = malloc(sizeof(struct circleq_dnsentry));
153
154 if (q == NULL) {
155 yp_error("failed to malloc() circleq dns entry");
156 return(NULL);
157 }
158
159 return(q);
160 }
161
162 /*
163 * Transmit a query.
164 */
165 static unsigned long
yp_send_dns_query(char * name,int type)166 yp_send_dns_query(char *name, int type)
167 {
168 char buf[MAXPACKET];
169 int n;
170 HEADER *hptr;
171 int ns;
172 int rval;
173 unsigned long id;
174
175 bzero(buf, sizeof(buf));
176
177 n = res_mkquery(QUERY,name,C_IN,type,NULL,0,NULL,buf,sizeof(buf));
178
179 if (n <= 0) {
180 yp_error("res_mkquery failed for %s type %d", name, type);
181 return(0);
182 }
183
184 hptr = (HEADER *)&buf;
185 id = ntohs(hptr->id);
186
187 for (ns = 0; ns < _res.nscount; ns++) {
188 rval = sendto(resfd, buf, n, 0,
189 (struct sockaddr *)&_res.nsaddr_list[ns],
190 sizeof(struct sockaddr));
191 if (rval == -1) {
192 yp_error("sendto failed");
193 return(0);
194 }
195 }
196
197 return(id);
198 }
199
200 static struct circleq_dnsentry *
yp_find_dnsqent(unsigned long id,int type)201 yp_find_dnsqent(unsigned long id, int type)
202 {
203 register struct circleq_dnsentry *q;
204
205 TAILQ_FOREACH(q, &qhead, links) {
206 switch (type) {
207 case BY_RPC_XID:
208 if (id == q->xid)
209 return(q);
210 break;
211 case BY_DNS_ID:
212 default:
213 if (id == q->id)
214 return(q);
215 break;
216 }
217 }
218 return (NULL);
219 }
220
221 static void
yp_send_dns_reply(struct circleq_dnsentry * q,char * buf)222 yp_send_dns_reply(struct circleq_dnsentry *q, char *buf)
223 {
224 ypresponse result_v1;
225 ypresp_val result_v2;
226 unsigned long xid;
227 struct sockaddr_in client_addr;
228 xdrproc_t xdrfunc;
229 char *result;
230
231 /*
232 * Set up correct reply struct and
233 * XDR filter depending on ypvers.
234 */
235 switch (q->ypvers) {
236 case YPVERS:
237 bzero((char *)&result_v2, sizeof(result_v2));
238
239 if (buf == NULL)
240 result_v2.stat = YP_NOKEY;
241 else {
242 result_v2.val.valdat_len = strlen(buf);
243 result_v2.val.valdat_val = buf;
244 result_v2.stat = YP_TRUE;
245 }
246 result = (char *)&result_v2;
247 xdrfunc = (xdrproc_t)xdr_ypresp_val;
248 break;
249 case YPOLDVERS:
250 /*
251 * The odds are we will _never_ execute this
252 * particular code, but we include it anyway
253 * for the sake of completeness.
254 */
255 bzero((char *)&result_v1, sizeof(result_v1));
256 result_v1.yp_resptype = YPRESP_VAL;
257
258 #define YPVAL ypresponse_u.yp_resp_valtype
259 if (buf == NULL)
260 result_v1.YPVAL.stat = YP_NOKEY;
261 else {
262 result_v1.YPVAL.val.valdat_len = strlen(buf);
263 result_v1.YPVAL.val.valdat_val = buf;
264 result_v1.YPVAL.stat = YP_TRUE;
265 }
266 result = (char *)&result_v1;
267 xdrfunc = (xdrproc_t)xdr_ypresponse;
268 break;
269 default:
270 yp_error("bad YP program version (%lu)!", q->ypvers);
271 return;
272 break;
273 }
274
275 if (debug)
276 yp_error("sending dns reply to %s (%lu)",
277 inet_ntoa(q->client_addr.sin_addr), q->id);
278 /*
279 * XXX This is disgusting. There's basically one transport
280 * handle for UDP, but we're holding off on replying to a
281 * client until we're ready, by which time we may have received
282 * several other queries from other clients with different
283 * transaction IDs. So to make the delayed response thing work,
284 * we have to save the transaction ID and client address of
285 * each request, then jam them into the transport handle when
286 * we're ready to send a reply. Then after we've send the reply,
287 * we put the old transaction ID and remote address back the
288 * way we found 'em. This is _INCREDIBLY_ non-portable; it's
289 * not even supported by the RPC library.
290 */
291 /*
292 * XXX Don't frob the transaction ID for TCP handles.
293 */
294 if (q->prot_type == SOCK_DGRAM)
295 xid = svcudp_set_xid(q->xprt, q->xid);
296 client_addr = q->xprt->xp_raddr;
297 q->xprt->xp_raddr = q->client_addr;
298
299 if (!svc_sendreply(q->xprt, xdrfunc, result))
300 yp_error("svc_sendreply failed");
301
302 /*
303 * Now that we sent the reply,
304 * put the handle back the way it was.
305 */
306 if (q->prot_type == SOCK_DGRAM)
307 svcudp_set_xid(q->xprt, xid);
308 q->xprt->xp_raddr = client_addr;
309 }
310
311 /*
312 * Decrement TTL on all queue entries, possibly nuking
313 * any that have been around too long without being serviced.
314 */
315 void
yp_prune_dnsq(void)316 yp_prune_dnsq(void)
317 {
318 register struct circleq_dnsentry *q, *n;
319
320 q = TAILQ_FIRST(&qhead);
321 while (q != NULL) {
322 q->ttl--;
323 n = TAILQ_NEXT(q, links);
324 if (!q->ttl) {
325 TAILQ_REMOVE(&qhead, q, links);
326 free(q->name);
327 free(q);
328 pending--;
329 }
330 q = n;
331 }
332
333 if (pending < 0)
334 pending = 0;
335 }
336
337 /*
338 * Data is pending on the DNS socket; check for valid replies
339 * to our queries and dispatch them to waiting clients.
340 */
341 void
yp_run_dnsq(void)342 yp_run_dnsq(void)
343 {
344 register struct circleq_dnsentry *q;
345 char buf[sizeof(HEADER) + MAXPACKET];
346 struct sockaddr_in sin;
347 socklen_t len;
348 int rval;
349 HEADER *hptr;
350 struct hostent *hent;
351
352 if (debug)
353 yp_error("running dns queue");
354
355 bzero(buf, sizeof(buf));
356
357 len = sizeof(struct sockaddr_in);
358 rval = recvfrom(resfd, buf, sizeof(buf), 0,
359 (struct sockaddr *)&sin, &len);
360
361 if (rval == -1) {
362 yp_error("recvfrom failed: %s", strerror(errno));
363 return;
364 }
365
366 /*
367 * We may have data left in the socket that represents
368 * replies to earlier queries that we don't care about
369 * anymore. If there are no lookups pending or the packet
370 * ID doesn't match any of the queue IDs, just drop it
371 * on the floor.
372 */
373 hptr = (HEADER *)&buf;
374 if (!pending ||
375 (q = yp_find_dnsqent(ntohs(hptr->id), BY_DNS_ID)) == NULL) {
376 /* ignore */
377 return;
378 }
379
380 if (debug)
381 yp_error("got dns reply from %s", inet_ntoa(sin.sin_addr));
382
383 hent = __dns_getanswer(buf, rval, q->name, q->type);
384
385 if (hent != NULL) {
386 if (q->type == T_PTR) {
387 hent->h_addr = (char *)q->addr;
388 hent->h_addrtype = q->addrtype;
389 hent->h_length = q->addrlen;
390 }
391 }
392
393 /* Got an answer ready for a client -- send it off. */
394 yp_send_dns_reply(q, parse(hent));
395 pending--;
396 TAILQ_REMOVE(&qhead, q, links);
397 free(q->name);
398 free(q);
399
400 /* Decrement TTLs on other entries while we're here. */
401 yp_prune_dnsq();
402 }
403
404 /*
405 * Queue and transmit an asynchronous DNS hostname lookup.
406 */
407 ypstat
yp_async_lookup_name(struct svc_req * rqstp,char * name,int af)408 yp_async_lookup_name(struct svc_req *rqstp, char *name, int af)
409 {
410 register struct circleq_dnsentry *q;
411 socklen_t len;
412 int type;
413
414 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */
415 type = -1;
416 len = sizeof(type);
417 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET,
418 SO_TYPE, &type, &len) == -1) {
419 yp_error("getsockopt failed: %s", strerror(errno));
420 return(YP_YPERR);
421 }
422
423 /* Avoid transmitting dupe requests. */
424 if (type == SOCK_DGRAM &&
425 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL)
426 return(YP_TRUE);
427
428 if ((q = yp_malloc_dnsent()) == NULL)
429 return(YP_YPERR);
430
431 q->type = (af == AF_INET) ? T_A : T_AAAA;
432 q->ttl = DEF_TTL;
433 q->xprt = rqstp->rq_xprt;
434 q->ypvers = rqstp->rq_vers;
435 q->prot_type = type;
436 if (q->prot_type == SOCK_DGRAM)
437 q->xid = svcudp_get_xid(q->xprt);
438 q->client_addr = q->xprt->xp_raddr;
439 q->domain = _res.dnsrch;
440 q->id = yp_send_dns_query(name, q->type);
441
442 if (q->id == 0) {
443 yp_error("DNS query failed");
444 free(q);
445 return(YP_YPERR);
446 }
447
448 q->name = strdup(name);
449 TAILQ_INSERT_HEAD(&qhead, q, links);
450 pending++;
451
452 if (debug)
453 yp_error("queueing async DNS name lookup (%lu)", q->id);
454
455 yp_prune_dnsq();
456 return(YP_TRUE);
457 }
458
459 /*
460 * Queue and transmit an asynchronous DNS IP address lookup.
461 */
462 ypstat
yp_async_lookup_addr(struct svc_req * rqstp,char * addr,int af)463 yp_async_lookup_addr(struct svc_req *rqstp, char *addr, int af)
464 {
465 register struct circleq_dnsentry *q;
466 char buf[MAXHOSTNAMELEN], *qp;
467 uint32_t abuf[4]; /* IPv4 or IPv6 */
468 u_char *uaddr = (u_char *)abuf;
469 socklen_t len;
470 int type, n;
471
472 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */
473 type = -1;
474 len = sizeof(type);
475 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET,
476 SO_TYPE, &type, &len) == -1) {
477 yp_error("getsockopt failed: %s", strerror(errno));
478 return(YP_YPERR);
479 }
480
481 /* Avoid transmitting dupe requests. */
482 if (type == SOCK_DGRAM &&
483 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL)
484 return(YP_TRUE);
485
486 switch (af) {
487 case AF_INET:
488 if (inet_aton(addr, (struct in_addr *)uaddr) != 1)
489 return(YP_NOKEY);
490 snprintf(buf, sizeof(buf), "%u.%u.%u.%u.in-addr.arpa",
491 (uaddr[3] & 0xff), (uaddr[2] & 0xff),
492 (uaddr[1] & 0xff), (uaddr[0] & 0xff));
493 len = INADDRSZ;
494 break;
495 case AF_INET6:
496 if (inet_pton(af, addr, uaddr) != 1)
497 return(YP_NOKEY);
498 qp = buf;
499 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
500 qp += (size_t)sprintf(qp, "%x.%x.", uaddr[n] & 0xf,
501 (uaddr[n] >> 4) & 0xf);
502 }
503 strlcat(buf, "ip6.arpa", sizeof(buf));
504 len = IN6ADDRSZ;
505 break;
506 default:
507 return(YP_YPERR);
508 }
509
510 if ((q = yp_malloc_dnsent()) == NULL)
511 return(YP_YPERR);
512
513 if (debug)
514 yp_error("DNS address is: %s", buf);
515
516 q->type = T_PTR;
517 q->ttl = DEF_TTL;
518 q->xprt = rqstp->rq_xprt;
519 q->ypvers = rqstp->rq_vers;
520 q->domain = NULL;
521 q->prot_type = type;
522 if (q->prot_type == SOCK_DGRAM)
523 q->xid = svcudp_get_xid(q->xprt);
524 q->client_addr = q->xprt->xp_raddr;
525 q->id = yp_send_dns_query(buf, q->type);
526
527 if (q->id == 0) {
528 yp_error("DNS query failed");
529 free(q);
530 return(YP_YPERR);
531 }
532
533 memcpy(q->addr, uaddr, len);
534 q->addrlen = len;
535 q->addrtype = af;
536 q->name = strdup(buf);
537 TAILQ_INSERT_HEAD(&qhead, q, links);
538 pending++;
539
540 if (debug)
541 yp_error("queueing async DNS address lookup (%lu)", q->id);
542
543 yp_prune_dnsq();
544 return(YP_TRUE);
545 }
546