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 33 #ifndef lint 34 static const char rcsid[] = 35 "$FreeBSD$"; 36 #endif /* not lint */ 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 len,i; 74 struct in_addr addr; 75 76 if (hp == NULL) 77 return(NULL); 78 79 len = 16 + strlen(hp->h_name); 80 for (i = 0; hp->h_aliases[i]; i++) 81 len += strlen(hp->h_aliases[i]) + 1; 82 len++; 83 84 if (len > sizeof(result)) 85 return(NULL); 86 87 bzero(result, sizeof(result)); 88 89 bcopy(hp->h_addr, &addr, sizeof(struct in_addr)); 90 snprintf(result, sizeof(result), "%s %s", inet_ntoa(addr), hp->h_name); 91 92 for (i = 0; hp->h_aliases[i]; i++) { 93 strcat(result, " "); 94 strcat(result, hp->h_aliases[i]); 95 } 96 97 return ((char *)&result); 98 } 99 100 #define MAXPACKET 1024 101 #define DEF_TTL 50 102 103 #define BY_DNS_ID 1 104 #define BY_RPC_XID 2 105 106 extern struct hostent *__dns_getanswer(char *, int, char *, int); 107 108 static TAILQ_HEAD(dns_qhead, circleq_dnsentry) qhead; 109 110 struct circleq_dnsentry { 111 SVCXPRT *xprt; 112 unsigned long xid; 113 struct sockaddr_in client_addr; 114 unsigned long ypvers; 115 unsigned long id; 116 unsigned long ttl; 117 unsigned long type; 118 unsigned short prot_type; 119 char **domain; 120 char *name; 121 struct in_addr addr; 122 TAILQ_ENTRY(circleq_dnsentry) links; 123 }; 124 125 static int pending = 0; 126 127 int 128 yp_init_resolver(void) 129 { 130 TAILQ_INIT(&qhead); 131 if (!(_res.options & RES_INIT) && res_init() == -1) { 132 yp_error("res_init failed"); 133 return(1); 134 } 135 if ((resfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { 136 yp_error("couldn't create socket"); 137 return(1); 138 } 139 if (fcntl(resfd, F_SETFL, O_NONBLOCK) == -1) { 140 yp_error("couldn't make resolver socket non-blocking"); 141 return(1); 142 } 143 return(0); 144 } 145 146 static struct 147 circleq_dnsentry *yp_malloc_dnsent(void) 148 { 149 register struct circleq_dnsentry *q; 150 151 q = (struct circleq_dnsentry *)malloc(sizeof(struct circleq_dnsentry)); 152 153 if (q == NULL) { 154 yp_error("failed to malloc() circleq dns entry"); 155 return(NULL); 156 } 157 158 return(q); 159 } 160 161 /* 162 * Transmit a query. 163 */ 164 static unsigned long 165 yp_send_dns_query(char *name, int type) 166 { 167 char buf[MAXPACKET]; 168 int n; 169 HEADER *hptr; 170 int ns; 171 int rval; 172 unsigned long id; 173 174 bzero(buf, sizeof(buf)); 175 176 n = res_mkquery(QUERY,name,C_IN,type,NULL,0,NULL,buf,sizeof(buf)); 177 178 if (n <= 0) { 179 yp_error("res_mkquery failed"); 180 return(0); 181 } 182 183 hptr = (HEADER *)&buf; 184 id = ntohs(hptr->id); 185 186 for (ns = 0; ns < _res.nscount; ns++) { 187 rval = sendto(resfd, buf, n, 0, 188 (struct sockaddr *)&_res.nsaddr_list[ns], 189 sizeof(struct sockaddr)); 190 if (rval == -1) { 191 yp_error("sendto failed"); 192 return(0); 193 } 194 } 195 196 return(id); 197 } 198 199 static struct circleq_dnsentry * 200 yp_find_dnsqent(unsigned long id, int type) 201 { 202 register struct circleq_dnsentry *q; 203 204 TAILQ_FOREACH(q, &qhead, links) { 205 switch (type) { 206 case BY_RPC_XID: 207 if (id == q->xid) 208 return(q); 209 break; 210 case BY_DNS_ID: 211 default: 212 if (id == q->id) 213 return(q); 214 break; 215 } 216 } 217 return (NULL); 218 } 219 220 static void 221 yp_send_dns_reply(struct circleq_dnsentry *q, char *buf) 222 { 223 ypresponse result_v1; 224 ypresp_val result_v2; 225 unsigned long xid; 226 struct sockaddr_in client_addr; 227 xdrproc_t xdrfunc; 228 char *result; 229 230 /* 231 * Set up correct reply struct and 232 * XDR filter depending on ypvers. 233 */ 234 switch (q->ypvers) { 235 case YPVERS: 236 bzero((char *)&result_v2, sizeof(result_v2)); 237 238 if (buf == NULL) 239 result_v2.stat = YP_NOKEY; 240 else { 241 result_v2.val.valdat_len = strlen(buf); 242 result_v2.val.valdat_val = buf; 243 result_v2.stat = YP_TRUE; 244 } 245 result = (char *)&result_v2; 246 xdrfunc = (xdrproc_t)xdr_ypresp_val; 247 break; 248 case YPOLDVERS: 249 /* 250 * The odds are we will _never_ execute this 251 * particular code, but we include it anyway 252 * for the sake of completeness. 253 */ 254 bzero((char *)&result_v1, sizeof(result_v1)); 255 result_v1.yp_resptype = YPRESP_VAL; 256 257 #define YPVAL ypresponse_u.yp_resp_valtype 258 if (buf == NULL) 259 result_v1.YPVAL.stat = YP_NOKEY; 260 else { 261 result_v1.YPVAL.val.valdat_len = strlen(buf); 262 result_v1.YPVAL.val.valdat_val = buf; 263 result_v1.YPVAL.stat = YP_TRUE; 264 } 265 result = (char *)&result_v1; 266 xdrfunc = (xdrproc_t)xdr_ypresponse; 267 break; 268 default: 269 yp_error("bad YP program version (%lu)!", q->ypvers); 270 return; 271 break; 272 } 273 274 if (debug) 275 yp_error("sending dns reply to %s (%lu)", 276 inet_ntoa(q->client_addr.sin_addr), q->id); 277 /* 278 * XXX This is disgusting. There's basically one transport 279 * handle for UDP, but we're holding off on replying to a 280 * client until we're ready, by which time we may have received 281 * several other queries from other clients with different 282 * transaction IDs. So to make the delayed response thing work, 283 * we have to save the transaction ID and client address of 284 * each request, then jam them into the transport handle when 285 * we're ready to send a reply. Then after we've send the reply, 286 * we put the old transaction ID and remote address back the 287 * way we found 'em. This is _INCREDIBLY_ non-portable; it's 288 * not even supported by the RPC library. 289 */ 290 /* 291 * XXX Don't frob the transaction ID for TCP handles. 292 */ 293 if (q->prot_type == SOCK_DGRAM) 294 xid = svcudp_set_xid(q->xprt, q->xid); 295 client_addr = q->xprt->xp_raddr; 296 q->xprt->xp_raddr = q->client_addr; 297 298 if (!svc_sendreply(q->xprt, xdrfunc, result)) 299 yp_error("svc_sendreply failed"); 300 301 /* 302 * Now that we sent the reply, 303 * put the handle back the way it was. 304 */ 305 if (q->prot_type == SOCK_DGRAM) 306 svcudp_set_xid(q->xprt, xid); 307 q->xprt->xp_raddr = client_addr; 308 309 return; 310 } 311 312 /* 313 * Decrement TTL on all queue entries, possibly nuking 314 * any that have been around too long without being serviced. 315 */ 316 void 317 yp_prune_dnsq(void) 318 { 319 register struct circleq_dnsentry *q, *n; 320 321 q = TAILQ_FIRST(&qhead); 322 while (q != NULL) { 323 q->ttl--; 324 n = TAILQ_NEXT(q, links); 325 if (!q->ttl) { 326 TAILQ_REMOVE(&qhead, q, links); 327 free(q->name); 328 free(q); 329 pending--; 330 } 331 q = n; 332 } 333 334 if (pending < 0) 335 pending = 0; 336 337 return; 338 } 339 340 /* 341 * Data is pending on the DNS socket; check for valid replies 342 * to our queries and dispatch them to waiting clients. 343 */ 344 void 345 yp_run_dnsq(void) 346 { 347 register struct circleq_dnsentry *q; 348 char buf[sizeof(HEADER) + MAXPACKET]; 349 char retrybuf[MAXHOSTNAMELEN]; 350 struct sockaddr_in sin; 351 int rval; 352 int len; 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 /* 390 * If the lookup failed, try appending one of the domains 391 * from resolv.conf. If we have no domains to test, the 392 * query has failed. 393 */ 394 if (hent == NULL) { 395 if ((h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) 396 && q->domain && *q->domain) { 397 snprintf(retrybuf, sizeof(retrybuf), "%s.%s", 398 q->name, *q->domain); 399 if (debug) 400 yp_error("retrying with: %s", retrybuf); 401 q->id = yp_send_dns_query(retrybuf, q->type); 402 q->ttl = DEF_TTL; 403 q->domain++; 404 return; 405 } 406 } else { 407 if (q->type == T_PTR) { 408 hent->h_addr = (char *)&q->addr.s_addr; 409 hent->h_length = sizeof(struct in_addr); 410 } 411 } 412 413 /* Got an answer ready for a client -- send it off. */ 414 yp_send_dns_reply(q, parse(hent)); 415 pending--; 416 TAILQ_REMOVE(&qhead, q, links); 417 free(q->name); 418 free(q); 419 420 /* Decrement TTLs on other entries while we're here. */ 421 yp_prune_dnsq(); 422 423 return; 424 } 425 426 /* 427 * Queue and transmit an asynchronous DNS hostname lookup. 428 */ 429 ypstat 430 yp_async_lookup_name(struct svc_req *rqstp, char *name) 431 { 432 register struct circleq_dnsentry *q; 433 int type, len; 434 435 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */ 436 type = -1; len = sizeof(type); 437 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET, 438 SO_TYPE, &type, &len) == -1) { 439 yp_error("getsockopt failed: %s", strerror(errno)); 440 return(YP_YPERR); 441 } 442 443 /* Avoid transmitting dupe requests. */ 444 if (type == SOCK_DGRAM && 445 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL) 446 return(YP_TRUE); 447 448 if ((q = yp_malloc_dnsent()) == NULL) 449 return(YP_YPERR); 450 451 q->type = T_A; 452 q->ttl = DEF_TTL; 453 q->xprt = rqstp->rq_xprt; 454 q->ypvers = rqstp->rq_vers; 455 q->prot_type = type; 456 if (q->prot_type == SOCK_DGRAM) 457 q->xid = svcudp_get_xid(q->xprt); 458 q->client_addr = q->xprt->xp_raddr; 459 q->domain = _res.dnsrch; 460 q->id = yp_send_dns_query(name, q->type); 461 462 if (q->id == 0) { 463 yp_error("DNS query failed"); 464 free(q); 465 return(YP_YPERR); 466 } 467 468 q->name = strdup(name); 469 TAILQ_INSERT_HEAD(&qhead, q, links); 470 pending++; 471 472 if (debug) 473 yp_error("queueing async DNS name lookup (%d)", q->id); 474 475 yp_prune_dnsq(); 476 return(YP_TRUE); 477 } 478 479 /* 480 * Queue and transmit an asynchronous DNS IP address lookup. 481 */ 482 ypstat 483 yp_async_lookup_addr(struct svc_req *rqstp, char *addr) 484 { 485 register struct circleq_dnsentry *q; 486 char buf[MAXHOSTNAMELEN]; 487 int a, b, c, d; 488 int type, len; 489 490 /* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */ 491 type = -1; len = sizeof(type); 492 if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET, 493 SO_TYPE, &type, &len) == -1) { 494 yp_error("getsockopt failed: %s", strerror(errno)); 495 return(YP_YPERR); 496 } 497 498 /* Avoid transmitting dupe requests. */ 499 if (type == SOCK_DGRAM && 500 yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL) 501 return(YP_TRUE); 502 503 if ((q = yp_malloc_dnsent()) == NULL) 504 return(YP_YPERR); 505 506 if (sscanf(addr, "%d.%d.%d.%d", &a, &b, &c, &d) != 4) 507 return(YP_NOKEY); 508 509 snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", d, c, b, a); 510 511 if (debug) 512 yp_error("DNS address is: %s", buf); 513 514 q->type = T_PTR; 515 q->ttl = DEF_TTL; 516 q->xprt = rqstp->rq_xprt; 517 q->ypvers = rqstp->rq_vers; 518 q->domain = NULL; 519 q->prot_type = type; 520 if (q->prot_type == SOCK_DGRAM) 521 q->xid = svcudp_get_xid(q->xprt); 522 q->client_addr = q->xprt->xp_raddr; 523 q->id = yp_send_dns_query(buf, q->type); 524 525 if (q->id == 0) { 526 yp_error("DNS query failed"); 527 free(q); 528 return(YP_YPERR); 529 } 530 531 inet_aton(addr, &q->addr); 532 q->name = strdup(buf); 533 TAILQ_INSERT_HEAD(&qhead, q, links); 534 pending++; 535 536 if (debug) 537 yp_error("queueing async DNS address lookup (%d)", q->id); 538 539 yp_prune_dnsq(); 540 return(YP_TRUE); 541 } 542