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 __FBSDID("$FreeBSD$"); 37 38 /* 39 * Do standard and reverse DNS lookups using the resolver library. 40 * Take care of all the dirty work here so the main program only has to 41 * pass us a pointer to an array of characters. 42 * 43 * We have to use direct resolver calls here otherwise the YP server 44 * could end up looping by calling itself over and over again until 45 * it disappeared up its own belly button. 46 */ 47 48 #include <sys/param.h> 49 #include <sys/socket.h> 50 #include <sys/time.h> 51 #include <sys/fcntl.h> 52 #include <sys/queue.h> 53 #include <netinet/in.h> 54 #include <arpa/inet.h> 55 #include <arpa/nameser.h> 56 57 #include <ctype.h> 58 #include <errno.h> 59 #include <netdb.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <resolv.h> 64 #include <unistd.h> 65 66 #include <rpcsvc/yp.h> 67 #include "yp_extern.h" 68 69 static char * 70 parse(struct hostent *hp) 71 { 72 static char result[MAXHOSTNAMELEN * 2]; 73 int i; 74 size_t len; 75 char addr[46]; 76 77 if (hp == NULL) 78 return(NULL); 79 80 if (inet_ntop(hp->h_addrtype, hp->h_addr, addr, sizeof(addr)) == NULL) 81 return(NULL); 82 83 len = strlen(addr) + 1 + strlen(hp->h_name); 84 for (i = 0; hp->h_aliases[i]; i++) 85 len += strlen(hp->h_aliases[i]) + 1; 86 len++; 87 88 if (len > sizeof(result)) 89 return(NULL); 90 91 bzero(result, sizeof(result)); 92 snprintf(result, sizeof(result), "%s %s", addr, hp->h_name); 93 for (i = 0; hp->h_aliases[i]; i++) { 94 strcat(result, " "); 95 strcat(result, hp->h_aliases[i]); 96 } 97 98 return ((char *)&result); 99 } 100 101 #define MAXPACKET (64*1024) 102 #define DEF_TTL 50 103 104 #define BY_DNS_ID 1 105 #define BY_RPC_XID 2 106 107 extern struct hostent *__dns_getanswer(char *, int, char *, int); 108 109 static TAILQ_HEAD(dns_qhead, circleq_dnsentry) qhead; 110 111 struct circleq_dnsentry { 112 SVCXPRT *xprt; 113 unsigned long xid; 114 struct sockaddr_in client_addr; 115 unsigned long ypvers; 116 unsigned long id; 117 unsigned long ttl; 118 unsigned long type; 119 unsigned short prot_type; 120 char **domain; 121 char *name; 122 int addrtype; 123 int addrlen; 124 uint32_t addr[4]; /* IPv4 or IPv6 */ 125 TAILQ_ENTRY(circleq_dnsentry) links; 126 }; 127 128 static int pending = 0; 129 130 int 131 yp_init_resolver(void) 132 { 133 TAILQ_INIT(&qhead); 134 if (!(_res.options & RES_INIT) && res_init() == -1) { 135 yp_error("res_init failed"); 136 return(1); 137 } 138 if ((resfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 139 yp_error("couldn't create socket"); 140 return(1); 141 } 142 if (fcntl(resfd, F_SETFL, O_NONBLOCK) == -1) { 143 yp_error("couldn't make resolver socket non-blocking"); 144 return(1); 145 } 146 return(0); 147 } 148 149 static struct 150 circleq_dnsentry *yp_malloc_dnsent(void) 151 { 152 register struct circleq_dnsentry *q; 153 154 q = malloc(sizeof(struct circleq_dnsentry)); 155 156 if (q == NULL) { 157 yp_error("failed to malloc() circleq dns entry"); 158 return(NULL); 159 } 160 161 return(q); 162 } 163 164 /* 165 * Transmit a query. 166 */ 167 static unsigned long 168 yp_send_dns_query(char *name, int type) 169 { 170 char buf[MAXPACKET]; 171 int n; 172 HEADER *hptr; 173 int ns; 174 int rval; 175 unsigned long id; 176 177 bzero(buf, sizeof(buf)); 178 179 n = res_mkquery(QUERY,name,C_IN,type,NULL,0,NULL,buf,sizeof(buf)); 180 181 if (n <= 0) { 182 yp_error("res_mkquery failed for %s type %d", name, type); 183 return(0); 184 } 185 186 hptr = (HEADER *)&buf; 187 id = ntohs(hptr->id); 188 189 for (ns = 0; ns < _res.nscount; ns++) { 190 rval = sendto(resfd, buf, n, 0, 191 (struct sockaddr *)&_res.nsaddr_list[ns], 192 sizeof(struct sockaddr)); 193 if (rval == -1) { 194 yp_error("sendto failed"); 195 return(0); 196 } 197 } 198 199 return(id); 200 } 201 202 static struct circleq_dnsentry * 203 yp_find_dnsqent(unsigned long id, int type) 204 { 205 register struct circleq_dnsentry *q; 206 207 TAILQ_FOREACH(q, &qhead, links) { 208 switch (type) { 209 case BY_RPC_XID: 210 if (id == q->xid) 211 return(q); 212 break; 213 case BY_DNS_ID: 214 default: 215 if (id == q->id) 216 return(q); 217 break; 218 } 219 } 220 return (NULL); 221 } 222 223 static void 224 yp_send_dns_reply(struct circleq_dnsentry *q, char *buf) 225 { 226 ypresponse result_v1; 227 ypresp_val result_v2; 228 unsigned long xid; 229 struct sockaddr_in client_addr; 230 xdrproc_t xdrfunc; 231 char *result; 232 233 /* 234 * Set up correct reply struct and 235 * XDR filter depending on ypvers. 236 */ 237 switch (q->ypvers) { 238 case YPVERS: 239 bzero((char *)&result_v2, sizeof(result_v2)); 240 241 if (buf == NULL) 242 result_v2.stat = YP_NOKEY; 243 else { 244 result_v2.val.valdat_len = strlen(buf); 245 result_v2.val.valdat_val = buf; 246 result_v2.stat = YP_TRUE; 247 } 248 result = (char *)&result_v2; 249 xdrfunc = (xdrproc_t)xdr_ypresp_val; 250 break; 251 case YPOLDVERS: 252 /* 253 * The odds are we will _never_ execute this 254 * particular code, but we include it anyway 255 * for the sake of completeness. 256 */ 257 bzero((char *)&result_v1, sizeof(result_v1)); 258 result_v1.yp_resptype = YPRESP_VAL; 259 260 #define YPVAL ypresponse_u.yp_resp_valtype 261 if (buf == NULL) 262 result_v1.YPVAL.stat = YP_NOKEY; 263 else { 264 result_v1.YPVAL.val.valdat_len = strlen(buf); 265 result_v1.YPVAL.val.valdat_val = buf; 266 result_v1.YPVAL.stat = YP_TRUE; 267 } 268 result = (char *)&result_v1; 269 xdrfunc = (xdrproc_t)xdr_ypresponse; 270 break; 271 default: 272 yp_error("bad YP program version (%lu)!", q->ypvers); 273 return; 274 break; 275 } 276 277 if (debug) 278 yp_error("sending dns reply to %s (%lu)", 279 inet_ntoa(q->client_addr.sin_addr), q->id); 280 /* 281 * XXX This is disgusting. There's basically one transport 282 * handle for UDP, but we're holding off on replying to a 283 * client until we're ready, by which time we may have received 284 * several other queries from other clients with different 285 * transaction IDs. So to make the delayed response thing work, 286 * we have to save the transaction ID and client address of 287 * each request, then jam them into the transport handle when 288 * we're ready to send a reply. Then after we've send the reply, 289 * we put the old transaction ID and remote address back the 290 * way we found 'em. This is _INCREDIBLY_ non-portable; it's 291 * not even supported by the RPC library. 292 */ 293 /* 294 * XXX Don't frob the transaction ID for TCP handles. 295 */ 296 if (q->prot_type == SOCK_DGRAM) 297 xid = svcudp_set_xid(q->xprt, q->xid); 298 client_addr = q->xprt->xp_raddr; 299 q->xprt->xp_raddr = q->client_addr; 300 301 if (!svc_sendreply(q->xprt, xdrfunc, result)) 302 yp_error("svc_sendreply failed"); 303 304 /* 305 * Now that we sent the reply, 306 * put the handle back the way it was. 307 */ 308 if (q->prot_type == SOCK_DGRAM) 309 svcudp_set_xid(q->xprt, xid); 310 q->xprt->xp_raddr = client_addr; 311 312 return; 313 } 314 315 /* 316 * Decrement TTL on all queue entries, possibly nuking 317 * any that have been around too long without being serviced. 318 */ 319 void 320 yp_prune_dnsq(void) 321 { 322 register struct circleq_dnsentry *q, *n; 323 324 q = TAILQ_FIRST(&qhead); 325 while (q != NULL) { 326 q->ttl--; 327 n = TAILQ_NEXT(q, links); 328 if (!q->ttl) { 329 TAILQ_REMOVE(&qhead, q, links); 330 free(q->name); 331 free(q); 332 pending--; 333 } 334 q = n; 335 } 336 337 if (pending < 0) 338 pending = 0; 339 340 return; 341 } 342 343 /* 344 * Data is pending on the DNS socket; check for valid replies 345 * to our queries and dispatch them to waiting clients. 346 */ 347 void 348 yp_run_dnsq(void) 349 { 350 register struct circleq_dnsentry *q; 351 char buf[sizeof(HEADER) + MAXPACKET]; 352 struct sockaddr_in sin; 353 socklen_t len; 354 int rval; 355 HEADER *hptr; 356 struct hostent *hent; 357 358 if (debug) 359 yp_error("running dns queue"); 360 361 bzero(buf, sizeof(buf)); 362 363 len = sizeof(struct sockaddr_in); 364 rval = recvfrom(resfd, buf, sizeof(buf), 0, 365 (struct sockaddr *)&sin, &len); 366 367 if (rval == -1) { 368 yp_error("recvfrom failed: %s", strerror(errno)); 369 return; 370 } 371 372 /* 373 * We may have data left in the socket that represents 374 * replies to earlier queries that we don't care about 375 * anymore. If there are no lookups pending or the packet 376 * ID doesn't match any of the queue IDs, just drop it 377 * on the floor. 378 */ 379 hptr = (HEADER *)&buf; 380 if (!pending || 381 (q = yp_find_dnsqent(ntohs(hptr->id), BY_DNS_ID)) == NULL) { 382 /* ignore */ 383 return; 384 } 385 386 if (debug) 387 yp_error("got dns reply from %s", inet_ntoa(sin.sin_addr)); 388 389 hent = __dns_getanswer(buf, rval, q->name, q->type); 390 391 if (hent != NULL) { 392 if (q->type == T_PTR) { 393 hent->h_addr = (char *)q->addr; 394 hent->h_addrtype = q->addrtype; 395 hent->h_length = q->addrlen; 396 } 397 } 398 399 /* Got an answer ready for a client -- send it off. */ 400 yp_send_dns_reply(q, parse(hent)); 401 pending--; 402 TAILQ_REMOVE(&qhead, q, links); 403 free(q->name); 404 free(q); 405 406 /* Decrement TTLs on other entries while we're here. */ 407 yp_prune_dnsq(); 408 409 return; 410 } 411 412 /* 413 * Queue and transmit an asynchronous DNS hostname lookup. 414 */ 415 ypstat 416 yp_async_lookup_name(struct svc_req *rqstp, char *name, int af) 417 { 418 register struct circleq_dnsentry *q; 419 socklen_t len; 420 int type; 421 422 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */ 423 type = -1; 424 len = sizeof(type); 425 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET, 426 SO_TYPE, &type, &len) == -1) { 427 yp_error("getsockopt failed: %s", strerror(errno)); 428 return(YP_YPERR); 429 } 430 431 /* Avoid transmitting dupe requests. */ 432 if (type == SOCK_DGRAM && 433 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL) 434 return(YP_TRUE); 435 436 if ((q = yp_malloc_dnsent()) == NULL) 437 return(YP_YPERR); 438 439 q->type = (af == AF_INET) ? T_A : T_AAAA; 440 q->ttl = DEF_TTL; 441 q->xprt = rqstp->rq_xprt; 442 q->ypvers = rqstp->rq_vers; 443 q->prot_type = type; 444 if (q->prot_type == SOCK_DGRAM) 445 q->xid = svcudp_get_xid(q->xprt); 446 q->client_addr = q->xprt->xp_raddr; 447 q->domain = _res.dnsrch; 448 q->id = yp_send_dns_query(name, q->type); 449 450 if (q->id == 0) { 451 yp_error("DNS query failed"); 452 free(q); 453 return(YP_YPERR); 454 } 455 456 q->name = strdup(name); 457 TAILQ_INSERT_HEAD(&qhead, q, links); 458 pending++; 459 460 if (debug) 461 yp_error("queueing async DNS name lookup (%lu)", q->id); 462 463 yp_prune_dnsq(); 464 return(YP_TRUE); 465 } 466 467 /* 468 * Queue and transmit an asynchronous DNS IP address lookup. 469 */ 470 ypstat 471 yp_async_lookup_addr(struct svc_req *rqstp, char *addr, int af) 472 { 473 register struct circleq_dnsentry *q; 474 char buf[MAXHOSTNAMELEN], *qp; 475 uint32_t abuf[4]; /* IPv4 or IPv6 */ 476 u_char *uaddr = (u_char *)abuf; 477 socklen_t len; 478 int type, n; 479 480 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */ 481 type = -1; 482 len = sizeof(type); 483 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET, 484 SO_TYPE, &type, &len) == -1) { 485 yp_error("getsockopt failed: %s", strerror(errno)); 486 return(YP_YPERR); 487 } 488 489 /* Avoid transmitting dupe requests. */ 490 if (type == SOCK_DGRAM && 491 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL) 492 return(YP_TRUE); 493 494 switch (af) { 495 case AF_INET: 496 if (inet_aton(addr, (struct in_addr *)uaddr) != 1) 497 return(YP_NOKEY); 498 snprintf(buf, sizeof(buf), "%u.%u.%u.%u.in-addr.arpa", 499 (uaddr[3] & 0xff), (uaddr[2] & 0xff), 500 (uaddr[1] & 0xff), (uaddr[0] & 0xff)); 501 len = INADDRSZ; 502 break; 503 case AF_INET6: 504 if (inet_pton(af, addr, uaddr) != 1) 505 return(YP_NOKEY); 506 qp = buf; 507 for (n = IN6ADDRSZ - 1; n >= 0; n--) { 508 qp += (size_t)sprintf(qp, "%x.%x.", uaddr[n] & 0xf, 509 (uaddr[n] >> 4) & 0xf); 510 } 511 strlcat(buf, "ip6.arpa", sizeof(buf)); 512 len = IN6ADDRSZ; 513 break; 514 default: 515 return(YP_YPERR); 516 } 517 518 if ((q = yp_malloc_dnsent()) == NULL) 519 return(YP_YPERR); 520 521 if (debug) 522 yp_error("DNS address is: %s", buf); 523 524 q->type = T_PTR; 525 q->ttl = DEF_TTL; 526 q->xprt = rqstp->rq_xprt; 527 q->ypvers = rqstp->rq_vers; 528 q->domain = NULL; 529 q->prot_type = type; 530 if (q->prot_type == SOCK_DGRAM) 531 q->xid = svcudp_get_xid(q->xprt); 532 q->client_addr = q->xprt->xp_raddr; 533 q->id = yp_send_dns_query(buf, q->type); 534 535 if (q->id == 0) { 536 yp_error("DNS query failed"); 537 free(q); 538 return(YP_YPERR); 539 } 540 541 memcpy(q->addr, uaddr, len); 542 q->addrlen = len; 543 q->addrtype = af; 544 q->name = strdup(buf); 545 TAILQ_INSERT_HEAD(&qhead, q, links); 546 pending++; 547 548 if (debug) 549 yp_error("queueing async DNS address lookup (%lu)", q->id); 550 551 yp_prune_dnsq(); 552 return(YP_TRUE); 553 } 554