1 /* 2 * Copyright (c) 1995, 1996 3 * Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Bill Paul. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * $FreeBSD: src/usr.sbin/ypserv/yp_dnslookup.c,v 1.27 2005/05/20 13:04:10 charnier Exp $ 33 * $DragonFly: src/usr.sbin/ypserv/yp_dnslookup.c,v 1.4 2005/11/24 22:23:02 swildner Exp $ 34 */ 35 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 * 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 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 circleq_dnsentry * 148 yp_malloc_dnsent(void) 149 { 150 struct circleq_dnsentry *q; 151 152 q = (struct circleq_dnsentry *)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 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 * 201 yp_find_dnsqent(unsigned long id, int type) 202 { 203 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 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 return; 311 } 312 313 /* 314 * Decrement TTL on all queue entries, possibly nuking 315 * any that have been around too long without being serviced. 316 */ 317 void 318 yp_prune_dnsq(void) 319 { 320 struct circleq_dnsentry *q, *n; 321 322 q = TAILQ_FIRST(&qhead); 323 while (q != NULL) { 324 q->ttl--; 325 n = TAILQ_NEXT(q, links); 326 if (!q->ttl) { 327 TAILQ_REMOVE(&qhead, q, links); 328 free(q->name); 329 free(q); 330 pending--; 331 } 332 q = n; 333 } 334 335 if (pending < 0) 336 pending = 0; 337 338 return; 339 } 340 341 /* 342 * Data is pending on the DNS socket; check for valid replies 343 * to our queries and dispatch them to waiting clients. 344 */ 345 void 346 yp_run_dnsq(void) 347 { 348 struct circleq_dnsentry *q; 349 char buf[sizeof(HEADER) + MAXPACKET]; 350 struct sockaddr_in sin; 351 socklen_t len; 352 int rval; 353 HEADER *hptr; 354 struct hostent *hent; 355 356 if (debug) 357 yp_error("running dns queue"); 358 359 bzero(buf, sizeof(buf)); 360 361 len = sizeof(struct sockaddr_in); 362 rval = recvfrom(resfd, buf, sizeof(buf), 0, 363 (struct sockaddr *)&sin, &len); 364 365 if (rval == -1) { 366 yp_error("recvfrom failed: %s", strerror(errno)); 367 return; 368 } 369 370 /* 371 * We may have data left in the socket that represents 372 * replies to earlier queries that we don't care about 373 * anymore. If there are no lookups pending or the packet 374 * ID doesn't match any of the queue IDs, just drop it 375 * on the floor. 376 */ 377 hptr = (HEADER *)&buf; 378 if (!pending || 379 (q = yp_find_dnsqent(ntohs(hptr->id), BY_DNS_ID)) == NULL) { 380 /* ignore */ 381 return; 382 } 383 384 if (debug) 385 yp_error("got dns reply from %s", inet_ntoa(sin.sin_addr)); 386 387 hent = __dns_getanswer(buf, rval, q->name, q->type); 388 389 if (hent != NULL) { 390 if (q->type == T_PTR) { 391 hent->h_addr = (char *)q->addr; 392 hent->h_addrtype = q->addrtype; 393 hent->h_length = q->addrlen; 394 } 395 } 396 397 /* Got an answer ready for a client -- send it off. */ 398 yp_send_dns_reply(q, parse(hent)); 399 pending--; 400 TAILQ_REMOVE(&qhead, q, links); 401 free(q->name); 402 free(q); 403 404 /* Decrement TTLs on other entries while we're here. */ 405 yp_prune_dnsq(); 406 407 return; 408 } 409 410 /* 411 * Queue and transmit an asynchronous DNS hostname lookup. 412 */ 413 ypstat 414 yp_async_lookup_name(struct svc_req *rqstp, char *name, int af) 415 { 416 struct circleq_dnsentry *q; 417 socklen_t len; 418 int type; 419 420 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */ 421 type = -1; 422 len = sizeof(type); 423 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET, 424 SO_TYPE, &type, &len) == -1) { 425 yp_error("getsockopt failed: %s", strerror(errno)); 426 return(YP_YPERR); 427 } 428 429 /* Avoid transmitting dupe requests. */ 430 if (type == SOCK_DGRAM && 431 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL) 432 return(YP_TRUE); 433 434 if ((q = yp_malloc_dnsent()) == NULL) 435 return(YP_YPERR); 436 437 q->type = (af == AF_INET) ? T_A : T_AAAA; 438 q->ttl = DEF_TTL; 439 q->xprt = rqstp->rq_xprt; 440 q->ypvers = rqstp->rq_vers; 441 q->prot_type = type; 442 if (q->prot_type == SOCK_DGRAM) 443 q->xid = svcudp_get_xid(q->xprt); 444 q->client_addr = q->xprt->xp_raddr; 445 q->domain = _res.dnsrch; 446 q->id = yp_send_dns_query(name, q->type); 447 448 if (q->id == 0) { 449 yp_error("DNS query failed"); 450 free(q); 451 return(YP_YPERR); 452 } 453 454 q->name = strdup(name); 455 TAILQ_INSERT_HEAD(&qhead, q, links); 456 pending++; 457 458 if (debug) 459 yp_error("queueing async DNS name lookup (%d)", q->id); 460 461 yp_prune_dnsq(); 462 return(YP_TRUE); 463 } 464 465 /* 466 * Queue and transmit an asynchronous DNS IP address lookup. 467 */ 468 ypstat 469 yp_async_lookup_addr(struct svc_req *rqstp, char *addr, int af) 470 { 471 struct circleq_dnsentry *q; 472 char buf[MAXHOSTNAMELEN], *qp; 473 uint32_t abuf[4]; /* IPv4 or IPv6 */ 474 u_char *uaddr = (u_char *)abuf; 475 socklen_t len; 476 int type, n; 477 478 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */ 479 type = -1; 480 len = sizeof(type); 481 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET, 482 SO_TYPE, &type, &len) == -1) { 483 yp_error("getsockopt failed: %s", strerror(errno)); 484 return(YP_YPERR); 485 } 486 487 /* Avoid transmitting dupe requests. */ 488 if (type == SOCK_DGRAM && 489 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL) 490 return(YP_TRUE); 491 492 if ((q = yp_malloc_dnsent()) == NULL) 493 return(YP_YPERR); 494 495 switch (af) { 496 case AF_INET: 497 if (inet_aton(addr, (struct in_addr *)uaddr) != 1) 498 return(YP_NOKEY); 499 snprintf(buf, sizeof(buf), "%u.%u.%u.%u.in-addr.arpa", 500 (uaddr[3] & 0xff), (uaddr[2] & 0xff), 501 (uaddr[1] & 0xff), (uaddr[0] & 0xff)); 502 len = INADDRSZ; 503 break; 504 case AF_INET6: 505 if (inet_pton(af, addr, uaddr) != 1) 506 return(YP_NOKEY); 507 qp = buf; 508 for (n = IN6ADDRSZ - 1; n >= 0; n--) { 509 qp += (size_t)sprintf(qp, "%x.%x.", uaddr[n] & 0xf, 510 (uaddr[n] >> 4) & 0xf); 511 } 512 strlcat(buf, "ip6.arpa", sizeof(buf)); 513 len = IN6ADDRSZ; 514 break; 515 default: 516 return(YP_YPERR); 517 } 518 519 if (debug) 520 yp_error("DNS address is: %s", buf); 521 522 q->type = T_PTR; 523 q->ttl = DEF_TTL; 524 q->xprt = rqstp->rq_xprt; 525 q->ypvers = rqstp->rq_vers; 526 q->domain = NULL; 527 q->prot_type = type; 528 if (q->prot_type == SOCK_DGRAM) 529 q->xid = svcudp_get_xid(q->xprt); 530 q->client_addr = q->xprt->xp_raddr; 531 q->id = yp_send_dns_query(buf, q->type); 532 533 if (q->id == 0) { 534 yp_error("DNS query failed"); 535 free(q); 536 return(YP_YPERR); 537 } 538 539 memcpy(q->addr, uaddr, len); 540 q->addrlen = len; 541 q->addrtype = af; 542 q->name = strdup(buf); 543 TAILQ_INSERT_HEAD(&qhead, q, links); 544 pending++; 545 546 if (debug) 547 yp_error("queueing async DNS address lookup (%d)", q->id); 548 549 yp_prune_dnsq(); 550 return(YP_TRUE); 551 } 552