1 /* $OpenBSD: gethostnamadr_async.c,v 1.44 2018/04/28 15:16:49 schwarze 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 async_set_state(as, ASR_STATE_NEXT_DB); 208 break; 209 210 case ASR_STATE_NEXT_DB: 211 212 if (_asr_iter_db(as) == -1) { 213 async_set_state(as, ASR_STATE_NOT_FOUND); 214 break; 215 } 216 217 switch (AS_DB(as)) { 218 219 case ASR_DB_DNS: 220 221 /* Create a subquery to do the DNS lookup */ 222 223 if (as->as_type == ASR_GETHOSTBYNAME) { 224 type = (as->as.hostnamadr.family == AF_INET) ? 225 T_A : T_AAAA; 226 as->as_subq = _res_search_async_ctx( 227 as->as.hostnamadr.name, 228 C_IN, type, as->as_ctx); 229 } else { 230 _asr_addr_as_fqdn(as->as.hostnamadr.addr, 231 as->as.hostnamadr.family, 232 name, sizeof(name)); 233 as->as_subq = _res_query_async_ctx( 234 name, C_IN, T_PTR, as->as_ctx); 235 } 236 237 if (as->as_subq == NULL) { 238 ar->ar_errno = errno; 239 ar->ar_h_errno = NETDB_INTERNAL; 240 async_set_state(as, ASR_STATE_HALT); 241 break; 242 } 243 244 async_set_state(as, ASR_STATE_SUBQUERY); 245 break; 246 247 case ASR_DB_FILE: 248 249 /* Try to find a match in the host file */ 250 251 if ((f = fopen(_PATH_HOSTS, "re")) == NULL) 252 break; 253 254 if (as->as_type == ASR_GETHOSTBYNAME) 255 data = as->as.hostnamadr.name; 256 else 257 data = as->as.hostnamadr.addr; 258 259 h = hostent_file_match(f, as->as_type, 260 as->as.hostnamadr.family, data, 261 as->as.hostnamadr.addrlen); 262 saved_errno = errno; 263 fclose(f); 264 errno = saved_errno; 265 266 if (h == NULL) { 267 if (errno) { 268 ar->ar_errno = errno; 269 ar->ar_h_errno = NETDB_INTERNAL; 270 async_set_state(as, ASR_STATE_HALT); 271 } 272 /* otherwise not found */ 273 break; 274 } 275 ar->ar_hostent = &h->h; 276 ar->ar_h_errno = NETDB_SUCCESS; 277 async_set_state(as, ASR_STATE_HALT); 278 break; 279 } 280 break; 281 282 case ASR_STATE_SUBQUERY: 283 284 /* Run the DNS subquery. */ 285 286 if ((r = asr_run(as->as_subq, ar)) == ASYNC_COND) 287 return (ASYNC_COND); 288 289 /* Done. */ 290 as->as_subq = NULL; 291 292 if (ar->ar_datalen == -1) { 293 async_set_state(as, ASR_STATE_NEXT_DB); 294 break; 295 } 296 297 /* If we got a packet but no anwser, use the next DB. */ 298 if (ar->ar_count == 0) { 299 free(ar->ar_data); 300 as->as.hostnamadr.subq_h_errno = ar->ar_h_errno; 301 async_set_state(as, ASR_STATE_NEXT_DB); 302 break; 303 } 304 305 /* Read the hostent from the packet. */ 306 307 h = hostent_from_packet(as->as_type, 308 as->as.hostnamadr.family, ar->ar_data, ar->ar_datalen); 309 free(ar->ar_data); 310 if (h == NULL) { 311 ar->ar_errno = errno; 312 ar->ar_h_errno = NETDB_INTERNAL; 313 async_set_state(as, ASR_STATE_HALT); 314 break; 315 } 316 317 if (as->as_type == ASR_GETHOSTBYADDR) { 318 if (hostent_add_addr(h, as->as.hostnamadr.addr, 319 as->as.hostnamadr.addrlen) == -1) { 320 free(h); 321 ar->ar_errno = errno; 322 ar->ar_h_errno = NETDB_INTERNAL; 323 async_set_state(as, ASR_STATE_HALT); 324 break; 325 } 326 } 327 328 /* 329 * No valid hostname or address found in the dns packet. 330 * Ignore it. 331 */ 332 if ((as->as_type == ASR_GETHOSTBYNAME && 333 h->h.h_addr_list[0] == NULL) || 334 h->h.h_name == NULL) { 335 free(h); 336 async_set_state(as, ASR_STATE_NEXT_DB); 337 break; 338 } 339 340 ar->ar_hostent = &h->h; 341 ar->ar_h_errno = NETDB_SUCCESS; 342 async_set_state(as, ASR_STATE_HALT); 343 break; 344 345 case ASR_STATE_NOT_FOUND: 346 ar->ar_errno = 0; 347 if (as->as.hostnamadr.subq_h_errno) 348 ar->ar_h_errno = as->as.hostnamadr.subq_h_errno; 349 else 350 ar->ar_h_errno = HOST_NOT_FOUND; 351 async_set_state(as, ASR_STATE_HALT); 352 break; 353 354 case ASR_STATE_HALT: 355 if (ar->ar_h_errno == NETDB_SUCCESS && 356 as->as_flags & ASYNC_GETNET) 357 netent_from_hostent(ar); 358 if (ar->ar_h_errno) { 359 ar->ar_hostent = NULL; 360 ar->ar_netent = NULL; 361 } else 362 ar->ar_errno = 0; 363 return (ASYNC_DONE); 364 365 default: 366 ar->ar_errno = EOPNOTSUPP; 367 ar->ar_h_errno = NETDB_INTERNAL; 368 ar->ar_gai_errno = EAI_SYSTEM; 369 async_set_state(as, ASR_STATE_HALT); 370 break; 371 } 372 goto next; 373 } 374 375 /* 376 * Create a hostent from a numeric address string. 377 */ 378 static struct hostent_ext * 379 hostent_from_addr(int family, const char *name, const char *addr) 380 { 381 struct hostent_ext *h; 382 383 if ((h = hostent_alloc(family)) == NULL) 384 return (NULL); 385 if (hostent_set_cname(h, name, 0) == -1) 386 goto fail; 387 if (hostent_add_addr(h, addr, h->h.h_length) == -1) 388 goto fail; 389 return (h); 390 fail: 391 free(h); 392 return (NULL); 393 } 394 395 /* 396 * Lookup the first matching entry in the hostfile, either by address or by 397 * name depending on reqtype, and build a hostent from the line. 398 */ 399 static struct hostent_ext * 400 hostent_file_match(FILE *f, int reqtype, int family, const char *data, 401 int datalen) 402 { 403 char *tokens[MAXTOKEN], addr[16], buf[BUFSIZ + 1]; 404 struct hostent_ext *h; 405 int n, i; 406 407 for (;;) { 408 n = _asr_parse_namedb_line(f, tokens, MAXTOKEN, buf, sizeof(buf)); 409 if (n == -1) { 410 errno = 0; /* ignore errors reading the file */ 411 return (NULL); 412 } 413 414 /* there must be an address and at least one name */ 415 if (n < 2) 416 continue; 417 418 if (reqtype == ASR_GETHOSTBYNAME) { 419 for (i = 1; i < n; i++) { 420 if (strcasecmp(data, tokens[i])) 421 continue; 422 if (inet_pton(family, tokens[0], addr) == 1) 423 goto found; 424 } 425 } else { 426 if (inet_pton(family, tokens[0], addr) == 1 && 427 memcmp(addr, data, datalen) == 0) 428 goto found; 429 } 430 } 431 432 found: 433 if ((h = hostent_alloc(family)) == NULL) 434 return (NULL); 435 if (hostent_set_cname(h, tokens[1], 0) == -1) 436 goto fail; 437 for (i = 2; i < n; i ++) 438 if (hostent_add_alias(h, tokens[i], 0) == -1) 439 goto fail; 440 if (hostent_add_addr(h, addr, h->h.h_length) == -1) 441 goto fail; 442 return (h); 443 fail: 444 free(h); 445 return (NULL); 446 } 447 448 /* 449 * Fill the hostent from the given DNS packet. 450 */ 451 static struct hostent_ext * 452 hostent_from_packet(int reqtype, int family, char *pkt, size_t pktlen) 453 { 454 struct hostent_ext *h; 455 struct asr_unpack p; 456 struct asr_dns_header hdr; 457 struct asr_dns_query q; 458 struct asr_dns_rr rr; 459 char dname[MAXDNAME]; 460 461 if ((h = hostent_alloc(family)) == NULL) 462 return (NULL); 463 464 _asr_unpack_init(&p, pkt, pktlen); 465 _asr_unpack_header(&p, &hdr); 466 for (; hdr.qdcount; hdr.qdcount--) 467 _asr_unpack_query(&p, &q); 468 strlcpy(dname, q.q_dname, sizeof(dname)); 469 470 for (; hdr.ancount; hdr.ancount--) { 471 _asr_unpack_rr(&p, &rr); 472 if (rr.rr_class != C_IN) 473 continue; 474 switch (rr.rr_type) { 475 476 case T_CNAME: 477 if (reqtype == ASR_GETHOSTBYNAME) { 478 if (hostent_add_alias(h, rr.rr_dname, 1) == -1) 479 goto fail; 480 } else { 481 if (strcasecmp(rr.rr_dname, dname) == 0) 482 strlcpy(dname, rr.rr.cname.cname, 483 sizeof(dname)); 484 } 485 break; 486 487 case T_PTR: 488 if (reqtype != ASR_GETHOSTBYADDR) 489 break; 490 if (strcasecmp(rr.rr_dname, dname) != 0) 491 continue; 492 if (hostent_set_cname(h, rr.rr.ptr.ptrname, 1) == -1) 493 hostent_add_alias(h, rr.rr.ptr.ptrname, 1); 494 break; 495 496 case T_A: 497 if (reqtype != ASR_GETHOSTBYNAME) 498 break; 499 if (family != AF_INET) 500 break; 501 if (hostent_set_cname(h, rr.rr_dname, 1) == -1) 502 ; 503 if (hostent_add_addr(h, &rr.rr.in_a.addr, 4) == -1) 504 goto fail; 505 break; 506 507 case T_AAAA: 508 if (reqtype != ASR_GETHOSTBYNAME) 509 break; 510 if (family != AF_INET6) 511 break; 512 if (hostent_set_cname(h, rr.rr_dname, 1) == -1) 513 ; 514 if (hostent_add_addr(h, &rr.rr.in_aaaa.addr6, 16) == -1) 515 goto fail; 516 break; 517 } 518 } 519 520 return (h); 521 fail: 522 free(h); 523 return (NULL); 524 } 525 526 static struct hostent_ext * 527 hostent_alloc(int family) 528 { 529 struct hostent_ext *h; 530 size_t alloc; 531 532 alloc = sizeof(*h) + 1024; 533 if ((h = calloc(1, alloc)) == NULL) 534 return (NULL); 535 536 h->h.h_addrtype = family; 537 h->h.h_length = (family == AF_INET) ? 4 : 16; 538 h->h.h_aliases = h->aliases; 539 h->h.h_addr_list = h->addrs; 540 h->pos = (char *)(h) + sizeof(*h); 541 h->end = h->pos + 1024; 542 543 return (h); 544 } 545 546 static int 547 hostent_set_cname(struct hostent_ext *h, const char *name, int isdname) 548 { 549 char buf[MAXDNAME]; 550 size_t n; 551 552 if (h->h.h_name) 553 return (-1); 554 555 if (isdname) { 556 _asr_strdname(name, buf, sizeof buf); 557 buf[strlen(buf) - 1] = '\0'; 558 if (!res_hnok(buf)) 559 return (-1); 560 name = buf; 561 } 562 563 n = strlen(name) + 1; 564 if (h->pos + n >= h->end) 565 return (-1); 566 567 h->h.h_name = h->pos; 568 memmove(h->pos, name, n); 569 h->pos += n; 570 return (0); 571 } 572 573 static int 574 hostent_add_alias(struct hostent_ext *h, const char *name, int isdname) 575 { 576 char buf[MAXDNAME]; 577 size_t i, n; 578 579 for (i = 0; i < MAXALIASES; i++) 580 if (h->aliases[i] == NULL) 581 break; 582 if (i == MAXALIASES) 583 return (0); 584 585 if (isdname) { 586 _asr_strdname(name, buf, sizeof buf); 587 buf[strlen(buf)-1] = '\0'; 588 if (!res_hnok(buf)) 589 return (-1); 590 name = buf; 591 } 592 593 n = strlen(name) + 1; 594 if (h->pos + n >= h->end) 595 return (0); 596 597 h->aliases[i] = h->pos; 598 memmove(h->pos, name, n); 599 h->pos += n; 600 return (0); 601 } 602 603 static int 604 hostent_add_addr(struct hostent_ext *h, const void *addr, size_t size) 605 { 606 int i; 607 608 for (i = 0; i < MAXADDRS; i++) 609 if (h->addrs[i] == NULL) 610 break; 611 if (i == MAXADDRS) 612 return (0); 613 614 if (h->pos + size >= h->end) 615 return (0); 616 617 h->addrs[i] = h->pos; 618 memmove(h->pos, addr, size); 619 h->pos += size; 620 return (0); 621 } 622 623 static void 624 netent_from_hostent(struct asr_result *ar) 625 { 626 struct in_addr *addr; 627 struct netent_ext *n; 628 struct hostent_ext *h; 629 char **na, **ha; 630 size_t sz; 631 632 /* Allocate and initialize the output. */ 633 if ((n = calloc(1, sizeof(*n) + 1024)) == NULL) { 634 ar->ar_h_errno = NETDB_INTERNAL; 635 ar->ar_errno = errno; 636 goto out; 637 } 638 n->pos = (char *)(n) + sizeof(*n); 639 n->end = n->pos + 1024; 640 n->n.n_name = n->pos; 641 n->n.n_aliases = n->aliases; 642 643 /* Copy the fixed-size data. */ 644 h = (struct hostent_ext *)ar->ar_hostent; 645 addr = (struct in_addr *)h->h.h_addr; 646 n->n.n_net = ntohl(addr->s_addr); 647 n->n.n_addrtype = h->h.h_addrtype; 648 649 /* Copy the network name. */ 650 sz = strlen(h->h.h_name) + 1; 651 memcpy(n->pos, h->h.h_name, sz); 652 n->pos += sz; 653 654 /* 655 * Copy the aliases. 656 * No overflow check is needed because we are merely copying 657 * a part of the data from a structure of the same size. 658 */ 659 na = n->aliases; 660 for (ha = h->aliases; *ha != NULL; ha++) { 661 sz = strlen(*ha) + 1; 662 memcpy(n->pos, *ha, sz); 663 *na++ = n->pos; 664 n->pos += sz; 665 } 666 *na = NULL; 667 668 /* Handle the return values. */ 669 ar->ar_netent = &n->n; 670 out: 671 free(ar->ar_hostent); 672 ar->ar_hostent = NULL; 673 } 674