1 /* $OpenBSD: gethostnamadr_async.c,v 1.47 2023/11/14 08:27:33 florian Exp $ */ 2 /* 3 * Copyright (c) 2012 Eric Faurot <eric@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/types.h> 19 #include <sys/socket.h> 20 #include <netinet/in.h> 21 #include <arpa/inet.h> 22 #include <arpa/nameser.h> 23 #include <netdb.h> 24 25 #include <asr.h> 26 #include <ctype.h> 27 #include <errno.h> 28 #include <resolv.h> /* for res_hnok */ 29 #include <stdlib.h> 30 #include <string.h> 31 #include <unistd.h> 32 #include <limits.h> 33 34 #include "asr_private.h" 35 36 #define MAXALIASES 35 37 #define MAXADDRS 35 38 39 struct hostent_ext { 40 struct hostent h; 41 char *aliases[MAXALIASES + 1]; 42 char *addrs[MAXADDRS + 1]; 43 char *end; 44 char *pos; 45 }; 46 47 struct netent_ext { 48 struct netent n; 49 char *aliases[MAXALIASES + 1]; 50 char *end; 51 char *pos; 52 }; 53 54 static int gethostnamadr_async_run(struct asr_query *, struct asr_result *); 55 static struct hostent_ext *hostent_alloc(int); 56 static int hostent_set_cname(struct hostent_ext *, const char *, int); 57 static int hostent_add_alias(struct hostent_ext *, const char *, int); 58 static int hostent_add_addr(struct hostent_ext *, const void *, size_t); 59 static struct hostent_ext *hostent_from_addr(int, const char *, const char *); 60 static struct hostent_ext *hostent_file_match(FILE *, int, int, const char *, 61 int); 62 static struct hostent_ext *hostent_from_packet(int, int, char *, size_t); 63 static void netent_from_hostent(struct asr_result *ar); 64 65 struct asr_query * 66 gethostbyname_async(const char *name, void *asr) 67 { 68 return gethostbyname2_async(name, AF_INET, asr); 69 } 70 DEF_WEAK(gethostbyname_async); 71 72 struct asr_query * 73 gethostbyname2_async(const char *name, int af, void *asr) 74 { 75 struct asr_ctx *ac; 76 struct asr_query *as; 77 78 /* the original segfaults */ 79 if (name == NULL) { 80 errno = EINVAL; 81 return (NULL); 82 } 83 84 ac = _asr_use_resolver(asr); 85 if ((as = _asr_async_new(ac, ASR_GETHOSTBYNAME)) == NULL) 86 goto abort; /* errno set */ 87 as->as_run = gethostnamadr_async_run; 88 89 as->as.hostnamadr.family = af; 90 if (af == AF_INET) 91 as->as.hostnamadr.addrlen = INADDRSZ; 92 else if (af == AF_INET6) 93 as->as.hostnamadr.addrlen = IN6ADDRSZ; 94 as->as.hostnamadr.name = strdup(name); 95 if (as->as.hostnamadr.name == NULL) 96 goto abort; /* errno set */ 97 98 _asr_ctx_unref(ac); 99 return (as); 100 101 abort: 102 if (as) 103 _asr_async_free(as); 104 _asr_ctx_unref(ac); 105 return (NULL); 106 } 107 DEF_WEAK(gethostbyname2_async); 108 109 struct asr_query * 110 gethostbyaddr_async(const void *addr, socklen_t len, int af, void *asr) 111 { 112 struct asr_ctx *ac; 113 struct asr_query *as; 114 115 ac = _asr_use_resolver(asr); 116 as = _gethostbyaddr_async_ctx(addr, len, af, ac); 117 _asr_ctx_unref(ac); 118 119 return (as); 120 } 121 DEF_WEAK(gethostbyaddr_async); 122 123 struct asr_query * 124 _gethostbyaddr_async_ctx(const void *addr, socklen_t len, int af, 125 struct asr_ctx *ac) 126 { 127 struct asr_query *as; 128 129 if ((as = _asr_async_new(ac, ASR_GETHOSTBYADDR)) == NULL) 130 goto abort; /* errno set */ 131 as->as_run = gethostnamadr_async_run; 132 133 as->as.hostnamadr.family = af; 134 as->as.hostnamadr.addrlen = len; 135 if (len > 0) 136 memmove(as->as.hostnamadr.addr, addr, (len > 16) ? 16 : len); 137 138 return (as); 139 140 abort: 141 if (as) 142 _asr_async_free(as); 143 return (NULL); 144 } 145 146 static int 147 gethostnamadr_async_run(struct asr_query *as, struct asr_result *ar) 148 { 149 struct hostent_ext *h; 150 int r, type, saved_errno; 151 FILE *f; 152 char name[MAXDNAME], *data, addr[16], *c; 153 154 next: 155 switch (as->as_state) { 156 157 case ASR_STATE_INIT: 158 159 if (as->as.hostnamadr.family != AF_INET && 160 as->as.hostnamadr.family != AF_INET6) { 161 ar->ar_h_errno = NETDB_INTERNAL; 162 ar->ar_errno = EAFNOSUPPORT; 163 async_set_state(as, ASR_STATE_HALT); 164 break; 165 } 166 167 if ((as->as.hostnamadr.family == AF_INET && 168 as->as.hostnamadr.addrlen != INADDRSZ) || 169 (as->as.hostnamadr.family == AF_INET6 && 170 as->as.hostnamadr.addrlen != IN6ADDRSZ)) { 171 ar->ar_h_errno = NETDB_INTERNAL; 172 ar->ar_errno = EINVAL; 173 async_set_state(as, ASR_STATE_HALT); 174 break; 175 } 176 177 if (as->as_type == ASR_GETHOSTBYNAME) { 178 179 if (as->as.hostnamadr.name[0] == '\0') { 180 ar->ar_h_errno = NO_DATA; 181 async_set_state(as, ASR_STATE_HALT); 182 break; 183 } 184 185 /* Name might be an IP address string */ 186 for (c = as->as.hostnamadr.name; *c; c++) 187 if (!isdigit((unsigned char)*c) && 188 *c != '.' && *c != ':') 189 break; 190 if (*c == 0 && 191 inet_pton(as->as.hostnamadr.family, 192 as->as.hostnamadr.name, addr) == 1) { 193 h = hostent_from_addr(as->as.hostnamadr.family, 194 as->as.hostnamadr.name, addr); 195 if (h == NULL) { 196 ar->ar_errno = errno; 197 ar->ar_h_errno = NETDB_INTERNAL; 198 } 199 else { 200 ar->ar_hostent = &h->h; 201 ar->ar_h_errno = NETDB_SUCCESS; 202 } 203 async_set_state(as, ASR_STATE_HALT); 204 break; 205 } 206 207 if (!hnok_lenient(as->as.hostnamadr.name)) { 208 ar->ar_gai_errno = EAI_FAIL; 209 async_set_state(as, ASR_STATE_HALT); 210 break; 211 } 212 } 213 async_set_state(as, ASR_STATE_NEXT_DB); 214 break; 215 216 case ASR_STATE_NEXT_DB: 217 218 if (_asr_iter_db(as) == -1) { 219 async_set_state(as, ASR_STATE_NOT_FOUND); 220 break; 221 } 222 223 switch (AS_DB(as)) { 224 225 case ASR_DB_DNS: 226 227 /* Create a subquery to do the DNS lookup */ 228 229 if (as->as_type == ASR_GETHOSTBYNAME) { 230 type = (as->as.hostnamadr.family == AF_INET) ? 231 T_A : T_AAAA; 232 as->as_subq = _res_search_async_ctx( 233 as->as.hostnamadr.name, 234 C_IN, type, as->as_ctx); 235 } else { 236 _asr_addr_as_fqdn(as->as.hostnamadr.addr, 237 as->as.hostnamadr.family, 238 name, sizeof(name)); 239 as->as_subq = _res_query_async_ctx( 240 name, C_IN, T_PTR, as->as_ctx); 241 } 242 243 if (as->as_subq == NULL) { 244 ar->ar_errno = errno; 245 ar->ar_h_errno = NETDB_INTERNAL; 246 async_set_state(as, ASR_STATE_HALT); 247 break; 248 } 249 250 async_set_state(as, ASR_STATE_SUBQUERY); 251 break; 252 253 case ASR_DB_FILE: 254 255 /* Try to find a match in the host file */ 256 257 if ((f = fopen(_PATH_HOSTS, "re")) == NULL) 258 break; 259 260 if (as->as_type == ASR_GETHOSTBYNAME) 261 data = as->as.hostnamadr.name; 262 else 263 data = as->as.hostnamadr.addr; 264 265 h = hostent_file_match(f, as->as_type, 266 as->as.hostnamadr.family, data, 267 as->as.hostnamadr.addrlen); 268 saved_errno = errno; 269 fclose(f); 270 errno = saved_errno; 271 272 if (h == NULL) { 273 if (errno) { 274 ar->ar_errno = errno; 275 ar->ar_h_errno = NETDB_INTERNAL; 276 async_set_state(as, ASR_STATE_HALT); 277 } 278 /* otherwise not found */ 279 break; 280 } 281 ar->ar_hostent = &h->h; 282 ar->ar_h_errno = NETDB_SUCCESS; 283 async_set_state(as, ASR_STATE_HALT); 284 break; 285 } 286 break; 287 288 case ASR_STATE_SUBQUERY: 289 290 /* Run the DNS subquery. */ 291 292 if ((r = asr_run(as->as_subq, ar)) == ASYNC_COND) 293 return (ASYNC_COND); 294 295 /* Done. */ 296 as->as_subq = NULL; 297 298 /* 299 * We either got no packet or a packet without an answer. 300 * Saveguard the h_errno and use the next DB. 301 */ 302 if (ar->ar_count == 0) { 303 free(ar->ar_data); 304 as->as.hostnamadr.subq_h_errno = ar->ar_h_errno; 305 async_set_state(as, ASR_STATE_NEXT_DB); 306 break; 307 } 308 309 /* Read the hostent from the packet. */ 310 311 h = hostent_from_packet(as->as_type, 312 as->as.hostnamadr.family, ar->ar_data, ar->ar_datalen); 313 free(ar->ar_data); 314 if (h == NULL) { 315 ar->ar_errno = errno; 316 ar->ar_h_errno = NETDB_INTERNAL; 317 async_set_state(as, ASR_STATE_HALT); 318 break; 319 } 320 321 if (as->as_type == ASR_GETHOSTBYADDR) { 322 if (hostent_add_addr(h, as->as.hostnamadr.addr, 323 as->as.hostnamadr.addrlen) == -1) { 324 free(h); 325 ar->ar_errno = errno; 326 ar->ar_h_errno = NETDB_INTERNAL; 327 async_set_state(as, ASR_STATE_HALT); 328 break; 329 } 330 } 331 332 /* 333 * No valid hostname or address found in the dns packet. 334 * Ignore it. 335 */ 336 if ((as->as_type == ASR_GETHOSTBYNAME && 337 h->h.h_addr_list[0] == NULL) || 338 h->h.h_name == NULL) { 339 free(h); 340 async_set_state(as, ASR_STATE_NEXT_DB); 341 break; 342 } 343 344 ar->ar_hostent = &h->h; 345 ar->ar_h_errno = NETDB_SUCCESS; 346 async_set_state(as, ASR_STATE_HALT); 347 break; 348 349 case ASR_STATE_NOT_FOUND: 350 ar->ar_errno = 0; 351 if (as->as.hostnamadr.subq_h_errno) 352 ar->ar_h_errno = as->as.hostnamadr.subq_h_errno; 353 else 354 ar->ar_h_errno = HOST_NOT_FOUND; 355 async_set_state(as, ASR_STATE_HALT); 356 break; 357 358 case ASR_STATE_HALT: 359 if (ar->ar_h_errno == NETDB_SUCCESS && 360 as->as_flags & ASYNC_GETNET) 361 netent_from_hostent(ar); 362 if (ar->ar_h_errno) { 363 ar->ar_hostent = NULL; 364 ar->ar_netent = NULL; 365 } else 366 ar->ar_errno = 0; 367 return (ASYNC_DONE); 368 369 default: 370 ar->ar_errno = EOPNOTSUPP; 371 ar->ar_h_errno = NETDB_INTERNAL; 372 ar->ar_gai_errno = EAI_SYSTEM; 373 async_set_state(as, ASR_STATE_HALT); 374 break; 375 } 376 goto next; 377 } 378 379 /* 380 * Create a hostent from a numeric address string. 381 */ 382 static struct hostent_ext * 383 hostent_from_addr(int family, const char *name, const char *addr) 384 { 385 struct hostent_ext *h; 386 387 if ((h = hostent_alloc(family)) == NULL) 388 return (NULL); 389 if (hostent_set_cname(h, name, 0) == -1) 390 goto fail; 391 if (hostent_add_addr(h, addr, h->h.h_length) == -1) 392 goto fail; 393 return (h); 394 fail: 395 free(h); 396 return (NULL); 397 } 398 399 /* 400 * Lookup the first matching entry in the hostfile, either by address or by 401 * name depending on reqtype, and build a hostent from the line. 402 */ 403 static struct hostent_ext * 404 hostent_file_match(FILE *f, int reqtype, int family, const char *data, 405 int datalen) 406 { 407 char *tokens[MAXTOKEN], addr[16], buf[BUFSIZ + 1]; 408 struct hostent_ext *h; 409 int n, i; 410 411 for (;;) { 412 n = _asr_parse_namedb_line(f, tokens, MAXTOKEN, buf, sizeof(buf)); 413 if (n == -1) { 414 errno = 0; /* ignore errors reading the file */ 415 return (NULL); 416 } 417 418 /* there must be an address and at least one name */ 419 if (n < 2) 420 continue; 421 422 if (reqtype == ASR_GETHOSTBYNAME) { 423 for (i = 1; i < n; i++) { 424 if (strcasecmp(data, tokens[i])) 425 continue; 426 if (inet_pton(family, tokens[0], addr) == 1) 427 goto found; 428 } 429 } else { 430 if (inet_pton(family, tokens[0], addr) == 1 && 431 memcmp(addr, data, datalen) == 0) 432 goto found; 433 } 434 } 435 436 found: 437 if ((h = hostent_alloc(family)) == NULL) 438 return (NULL); 439 if (hostent_set_cname(h, tokens[1], 0) == -1) 440 goto fail; 441 for (i = 2; i < n; i ++) 442 if (hostent_add_alias(h, tokens[i], 0) == -1) 443 goto fail; 444 if (hostent_add_addr(h, addr, h->h.h_length) == -1) 445 goto fail; 446 return (h); 447 fail: 448 free(h); 449 return (NULL); 450 } 451 452 /* 453 * Fill the hostent from the given DNS packet. 454 */ 455 static struct hostent_ext * 456 hostent_from_packet(int reqtype, int family, char *pkt, size_t pktlen) 457 { 458 struct hostent_ext *h; 459 struct asr_unpack p; 460 struct asr_dns_header hdr; 461 struct asr_dns_query q; 462 struct asr_dns_rr rr; 463 char dname[MAXDNAME]; 464 465 if ((h = hostent_alloc(family)) == NULL) 466 return (NULL); 467 468 _asr_unpack_init(&p, pkt, pktlen); 469 _asr_unpack_header(&p, &hdr); 470 for (; hdr.qdcount; hdr.qdcount--) 471 _asr_unpack_query(&p, &q); 472 strlcpy(dname, q.q_dname, sizeof(dname)); 473 474 for (; hdr.ancount; hdr.ancount--) { 475 _asr_unpack_rr(&p, &rr); 476 if (rr.rr_class != C_IN) 477 continue; 478 switch (rr.rr_type) { 479 480 case T_CNAME: 481 if (reqtype == ASR_GETHOSTBYNAME) { 482 if (hostent_add_alias(h, rr.rr_dname, 1) == -1) 483 goto fail; 484 } else { 485 if (strcasecmp(rr.rr_dname, dname) == 0) 486 strlcpy(dname, rr.rr.cname.cname, 487 sizeof(dname)); 488 } 489 break; 490 491 case T_PTR: 492 if (reqtype != ASR_GETHOSTBYADDR) 493 break; 494 if (strcasecmp(rr.rr_dname, dname) != 0) 495 continue; 496 if (hostent_set_cname(h, rr.rr.ptr.ptrname, 1) == -1) 497 hostent_add_alias(h, rr.rr.ptr.ptrname, 1); 498 break; 499 500 case T_A: 501 if (reqtype != ASR_GETHOSTBYNAME) 502 break; 503 if (family != AF_INET) 504 break; 505 if (hostent_set_cname(h, rr.rr_dname, 1) == -1) 506 ; 507 if (hostent_add_addr(h, &rr.rr.in_a.addr, 4) == -1) 508 goto fail; 509 break; 510 511 case T_AAAA: 512 if (reqtype != ASR_GETHOSTBYNAME) 513 break; 514 if (family != AF_INET6) 515 break; 516 if (hostent_set_cname(h, rr.rr_dname, 1) == -1) 517 ; 518 if (hostent_add_addr(h, &rr.rr.in_aaaa.addr6, 16) == -1) 519 goto fail; 520 break; 521 } 522 } 523 524 return (h); 525 fail: 526 free(h); 527 return (NULL); 528 } 529 530 static struct hostent_ext * 531 hostent_alloc(int family) 532 { 533 struct hostent_ext *h; 534 size_t alloc; 535 536 alloc = sizeof(*h) + 1024; 537 if ((h = calloc(1, alloc)) == NULL) 538 return (NULL); 539 540 h->h.h_addrtype = family; 541 h->h.h_length = (family == AF_INET) ? 4 : 16; 542 h->h.h_aliases = h->aliases; 543 h->h.h_addr_list = h->addrs; 544 h->pos = (char *)(h) + sizeof(*h); 545 h->end = h->pos + 1024; 546 547 return (h); 548 } 549 550 static int 551 hostent_set_cname(struct hostent_ext *h, const char *name, int isdname) 552 { 553 char buf[MAXDNAME]; 554 size_t n; 555 556 if (h->h.h_name) 557 return (-1); 558 559 if (isdname) { 560 _asr_strdname(name, buf, sizeof buf); 561 buf[strlen(buf) - 1] = '\0'; 562 if (!res_hnok(buf)) 563 return (-1); 564 name = buf; 565 } 566 567 n = strlen(name) + 1; 568 if (h->pos + n >= h->end) 569 return (-1); 570 571 h->h.h_name = h->pos; 572 memmove(h->pos, name, n); 573 h->pos += n; 574 return (0); 575 } 576 577 static int 578 hostent_add_alias(struct hostent_ext *h, const char *name, int isdname) 579 { 580 char buf[MAXDNAME]; 581 size_t i, n; 582 583 for (i = 0; i < MAXALIASES; i++) 584 if (h->aliases[i] == NULL) 585 break; 586 if (i == MAXALIASES) 587 return (0); 588 589 if (isdname) { 590 _asr_strdname(name, buf, sizeof buf); 591 buf[strlen(buf)-1] = '\0'; 592 if (!res_hnok(buf)) 593 return (-1); 594 name = buf; 595 } 596 597 n = strlen(name) + 1; 598 if (h->pos + n >= h->end) 599 return (0); 600 601 h->aliases[i] = h->pos; 602 memmove(h->pos, name, n); 603 h->pos += n; 604 return (0); 605 } 606 607 static int 608 hostent_add_addr(struct hostent_ext *h, const void *addr, size_t size) 609 { 610 int i; 611 612 for (i = 0; i < MAXADDRS; i++) 613 if (h->addrs[i] == NULL) 614 break; 615 if (i == MAXADDRS) 616 return (0); 617 618 if (h->pos + size >= h->end) 619 return (0); 620 621 h->addrs[i] = h->pos; 622 memmove(h->pos, addr, size); 623 h->pos += size; 624 return (0); 625 } 626 627 static void 628 netent_from_hostent(struct asr_result *ar) 629 { 630 struct in_addr *addr; 631 struct netent_ext *n; 632 struct hostent_ext *h; 633 char **na, **ha; 634 size_t sz; 635 636 /* Allocate and initialize the output. */ 637 if ((n = calloc(1, sizeof(*n) + 1024)) == NULL) { 638 ar->ar_h_errno = NETDB_INTERNAL; 639 ar->ar_errno = errno; 640 goto out; 641 } 642 n->pos = (char *)(n) + sizeof(*n); 643 n->end = n->pos + 1024; 644 n->n.n_name = n->pos; 645 n->n.n_aliases = n->aliases; 646 647 /* Copy the fixed-size data. */ 648 h = (struct hostent_ext *)ar->ar_hostent; 649 addr = (struct in_addr *)h->h.h_addr; 650 n->n.n_net = ntohl(addr->s_addr); 651 n->n.n_addrtype = h->h.h_addrtype; 652 653 /* Copy the network name. */ 654 sz = strlen(h->h.h_name) + 1; 655 memcpy(n->pos, h->h.h_name, sz); 656 n->pos += sz; 657 658 /* 659 * Copy the aliases. 660 * No overflow check is needed because we are merely copying 661 * a part of the data from a structure of the same size. 662 */ 663 na = n->aliases; 664 for (ha = h->aliases; *ha != NULL; ha++) { 665 sz = strlen(*ha) + 1; 666 memcpy(n->pos, *ha, sz); 667 *na++ = n->pos; 668 n->pos += sz; 669 } 670 *na = NULL; 671 672 /* Handle the return values. */ 673 ar->ar_netent = &n->n; 674 out: 675 free(ar->ar_hostent); 676 ar->ar_hostent = NULL; 677 } 678