Gilad Arnold | 968bf19 | 2015-07-17 00:23:30 -0700 | [diff] [blame] | 1 | |
| 2 | /* Copyright 1998 by the Massachusetts Institute of Technology. |
| 3 | * |
| 4 | * Permission to use, copy, modify, and distribute this |
| 5 | * software and its documentation for any purpose and without |
| 6 | * fee is hereby granted, provided that the above copyright |
| 7 | * notice appear in all copies and that both that copyright |
| 8 | * notice and this permission notice appear in supporting |
| 9 | * documentation, and that the name of M.I.T. not be used in |
| 10 | * advertising or publicity pertaining to distribution of the |
| 11 | * software without specific, written prior permission. |
| 12 | * M.I.T. makes no representations about the suitability of |
| 13 | * this software for any purpose. It is provided "as is" |
| 14 | * without express or implied warranty. |
| 15 | */ |
| 16 | |
| 17 | #include "ares_setup.h" |
| 18 | |
| 19 | #ifdef HAVE_SYS_SOCKET_H |
| 20 | # include <sys/socket.h> |
| 21 | #endif |
| 22 | #ifdef HAVE_NETINET_IN_H |
| 23 | # include <netinet/in.h> |
| 24 | #endif |
| 25 | #ifdef HAVE_NETDB_H |
| 26 | # include <netdb.h> |
| 27 | #endif |
| 28 | #ifdef HAVE_ARPA_INET_H |
| 29 | # include <arpa/inet.h> |
| 30 | #endif |
| 31 | #ifdef HAVE_ARPA_NAMESER_H |
| 32 | # include <arpa/nameser.h> |
| 33 | #else |
| 34 | # include "nameser.h" |
| 35 | #endif |
| 36 | #ifdef HAVE_ARPA_NAMESER_COMPAT_H |
| 37 | # include <arpa/nameser_compat.h> |
| 38 | #endif |
| 39 | |
| 40 | #include <stdio.h> |
| 41 | #include <stdlib.h> |
| 42 | #include <string.h> |
| 43 | #include <ctype.h> |
| 44 | #ifdef HAVE_STRINGS_H |
| 45 | #include <strings.h> |
| 46 | #endif |
| 47 | |
| 48 | #include "ares.h" |
| 49 | #include "inet_net_pton.h" |
| 50 | #include "bitncmp.h" |
| 51 | #include "ares_platform.h" |
| 52 | #include "ares_private.h" |
| 53 | |
| 54 | #ifdef WATT32 |
| 55 | #undef WIN32 |
| 56 | #endif |
| 57 | |
| 58 | struct host_query { |
| 59 | /* Arguments passed to ares_gethostbyname() */ |
| 60 | ares_channel channel; |
| 61 | char *name; |
| 62 | ares_host_callback callback; |
| 63 | void *arg; |
| 64 | int sent_family; /* this family is what was is being used */ |
| 65 | int want_family; /* this family is what is asked for in the API */ |
| 66 | const char *remaining_lookups; |
| 67 | int timeouts; |
| 68 | }; |
| 69 | |
| 70 | static void next_lookup(struct host_query *hquery, int status_code); |
| 71 | static void host_callback(void *arg, int status, int timeouts, |
| 72 | unsigned char *abuf, int alen); |
| 73 | static void end_hquery(struct host_query *hquery, int status, |
| 74 | struct hostent *host); |
| 75 | static int fake_hostent(const char *name, int family, |
| 76 | ares_host_callback callback, void *arg); |
| 77 | static int file_lookup(const char *name, int family, struct hostent **host); |
| 78 | static void sort_addresses(struct hostent *host, |
| 79 | const struct apattern *sortlist, int nsort); |
| 80 | static void sort6_addresses(struct hostent *host, |
| 81 | const struct apattern *sortlist, int nsort); |
| 82 | static int get_address_index(const struct in_addr *addr, |
| 83 | const struct apattern *sortlist, int nsort); |
| 84 | static int get6_address_index(const struct ares_in6_addr *addr, |
| 85 | const struct apattern *sortlist, int nsort); |
| 86 | |
| 87 | void ares_gethostbyname(ares_channel channel, const char *name, int family, |
| 88 | ares_host_callback callback, void *arg) |
| 89 | { |
| 90 | struct host_query *hquery; |
| 91 | |
| 92 | /* Right now we only know how to look up Internet addresses - and unspec |
| 93 | means try both basically. */ |
| 94 | switch (family) { |
| 95 | case AF_INET: |
| 96 | case AF_INET6: |
| 97 | case AF_UNSPEC: |
| 98 | break; |
| 99 | default: |
| 100 | callback(arg, ARES_ENOTIMP, 0, NULL); |
| 101 | return; |
| 102 | } |
| 103 | |
| 104 | if (fake_hostent(name, family, callback, arg)) |
| 105 | return; |
| 106 | |
| 107 | /* Allocate and fill in the host query structure. */ |
| 108 | hquery = malloc(sizeof(struct host_query)); |
| 109 | if (!hquery) |
| 110 | { |
| 111 | callback(arg, ARES_ENOMEM, 0, NULL); |
| 112 | return; |
| 113 | } |
| 114 | hquery->channel = channel; |
| 115 | hquery->name = strdup(name); |
| 116 | hquery->want_family = family; |
| 117 | hquery->sent_family = -1; /* nothing is sent yet */ |
| 118 | if (!hquery->name) { |
| 119 | free(hquery); |
| 120 | callback(arg, ARES_ENOMEM, 0, NULL); |
| 121 | return; |
| 122 | } |
| 123 | hquery->callback = callback; |
| 124 | hquery->arg = arg; |
| 125 | hquery->remaining_lookups = channel->lookups; |
| 126 | hquery->timeouts = 0; |
| 127 | |
| 128 | /* Start performing lookups according to channel->lookups. */ |
| 129 | next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */); |
| 130 | } |
| 131 | |
| 132 | static void next_lookup(struct host_query *hquery, int status_code) |
| 133 | { |
| 134 | const char *p; |
| 135 | struct hostent *host; |
| 136 | int status = status_code; |
| 137 | |
| 138 | for (p = hquery->remaining_lookups; *p; p++) |
| 139 | { |
| 140 | switch (*p) |
| 141 | { |
| 142 | case 'b': |
| 143 | /* DNS lookup */ |
| 144 | hquery->remaining_lookups = p + 1; |
| 145 | if ((hquery->want_family == AF_INET6) || |
| 146 | (hquery->want_family == AF_UNSPEC)) { |
| 147 | /* if inet6 or unspec, start out with AAAA */ |
| 148 | hquery->sent_family = AF_INET6; |
| 149 | ares_search(hquery->channel, hquery->name, C_IN, T_AAAA, |
| 150 | host_callback, hquery); |
| 151 | } |
| 152 | else { |
| 153 | hquery->sent_family = AF_INET; |
| 154 | ares_search(hquery->channel, hquery->name, C_IN, T_A, |
| 155 | host_callback, hquery); |
| 156 | } |
| 157 | return; |
| 158 | |
| 159 | case 'f': |
| 160 | /* Host file lookup */ |
| 161 | status = file_lookup(hquery->name, hquery->want_family, &host); |
| 162 | |
| 163 | /* this status check below previously checked for !ARES_ENOTFOUND, |
| 164 | but we should not assume that this single error code is the one |
| 165 | that can occur, as that is in fact no longer the case */ |
| 166 | if (status == ARES_SUCCESS) |
| 167 | { |
| 168 | end_hquery(hquery, status, host); |
| 169 | return; |
| 170 | } |
| 171 | status = status_code; /* Use original status code */ |
| 172 | break; |
| 173 | } |
| 174 | } |
| 175 | end_hquery(hquery, status, NULL); |
| 176 | } |
| 177 | |
| 178 | static void host_callback(void *arg, int status, int timeouts, |
| 179 | unsigned char *abuf, int alen) |
| 180 | { |
| 181 | struct host_query *hquery = (struct host_query *) arg; |
| 182 | ares_channel channel = hquery->channel; |
| 183 | struct hostent *host = NULL; |
| 184 | |
| 185 | hquery->timeouts += timeouts; |
| 186 | if (status == ARES_SUCCESS) |
| 187 | { |
| 188 | if (hquery->sent_family == AF_INET) |
| 189 | { |
| 190 | status = ares_parse_a_reply(abuf, alen, &host, NULL, NULL); |
| 191 | if (host && channel->nsort) |
| 192 | sort_addresses(host, channel->sortlist, channel->nsort); |
| 193 | } |
| 194 | else if (hquery->sent_family == AF_INET6) |
| 195 | { |
| 196 | status = ares_parse_aaaa_reply(abuf, alen, &host, NULL, NULL); |
| 197 | if ((status == ARES_ENODATA || status == ARES_EBADRESP) && |
| 198 | hquery->want_family == AF_UNSPEC) { |
| 199 | /* The query returned something but either there were no AAAA |
| 200 | records (e.g. just CNAME) or the response was malformed. Try |
| 201 | looking up A instead. */ |
| 202 | hquery->sent_family = AF_INET; |
| 203 | ares_search(hquery->channel, hquery->name, C_IN, T_A, |
| 204 | host_callback, hquery); |
| 205 | return; |
| 206 | } |
| 207 | if (host && channel->nsort) |
| 208 | sort6_addresses(host, channel->sortlist, channel->nsort); |
| 209 | } |
| 210 | end_hquery(hquery, status, host); |
| 211 | } |
| 212 | else if ((status == ARES_ENODATA || status == ARES_EBADRESP || |
| 213 | status == ARES_ETIMEOUT) && (hquery->sent_family == AF_INET6 && |
| 214 | hquery->want_family == AF_UNSPEC)) |
| 215 | { |
| 216 | /* The AAAA query yielded no useful result. Now look up an A instead. */ |
| 217 | hquery->sent_family = AF_INET; |
| 218 | ares_search(hquery->channel, hquery->name, C_IN, T_A, host_callback, |
| 219 | hquery); |
| 220 | } |
| 221 | else if (status == ARES_EDESTRUCTION) |
| 222 | end_hquery(hquery, status, NULL); |
| 223 | else |
| 224 | next_lookup(hquery, status); |
| 225 | } |
| 226 | |
| 227 | static void end_hquery(struct host_query *hquery, int status, |
| 228 | struct hostent *host) |
| 229 | { |
| 230 | hquery->callback(hquery->arg, status, hquery->timeouts, host); |
| 231 | if (host) |
| 232 | ares_free_hostent(host); |
| 233 | free(hquery->name); |
| 234 | free(hquery); |
| 235 | } |
| 236 | |
| 237 | /* If the name looks like an IP address, fake up a host entry, end the |
| 238 | * query immediately, and return true. Otherwise return false. |
| 239 | */ |
| 240 | static int fake_hostent(const char *name, int family, |
| 241 | ares_host_callback callback, void *arg) |
| 242 | { |
| 243 | struct hostent hostent; |
| 244 | char *aliases[1] = { NULL }; |
| 245 | char *addrs[2]; |
| 246 | int result = 0; |
| 247 | struct in_addr in; |
| 248 | struct ares_in6_addr in6; |
| 249 | |
| 250 | if (family == AF_INET || family == AF_INET6) |
| 251 | { |
| 252 | /* It only looks like an IP address if it's all numbers and dots. */ |
| 253 | int numdots = 0, valid = 1; |
| 254 | const char *p; |
| 255 | for (p = name; *p; p++) |
| 256 | { |
| 257 | if (!ISDIGIT(*p) && *p != '.') { |
| 258 | valid = 0; |
| 259 | break; |
| 260 | } else if (*p == '.') { |
| 261 | numdots++; |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | /* if we don't have 3 dots, it is illegal |
| 266 | * (although inet_addr doesn't think so). |
| 267 | */ |
| 268 | if (numdots != 3 || !valid) |
| 269 | result = 0; |
| 270 | else |
| 271 | result = ((in.s_addr = inet_addr(name)) == INADDR_NONE ? 0 : 1); |
| 272 | |
| 273 | if (result) |
| 274 | family = AF_INET; |
| 275 | } |
| 276 | if (family == AF_INET6) |
| 277 | result = (ares_inet_pton(AF_INET6, name, &in6) < 1 ? 0 : 1); |
| 278 | |
| 279 | if (!result) |
| 280 | return 0; |
| 281 | |
| 282 | if (family == AF_INET) |
| 283 | { |
| 284 | hostent.h_length = (int)sizeof(struct in_addr); |
| 285 | addrs[0] = (char *)∈ |
| 286 | } |
| 287 | else if (family == AF_INET6) |
| 288 | { |
| 289 | hostent.h_length = (int)sizeof(struct ares_in6_addr); |
| 290 | addrs[0] = (char *)&in6; |
| 291 | } |
| 292 | /* Duplicate the name, to avoid a constness violation. */ |
| 293 | hostent.h_name = strdup(name); |
| 294 | if (!hostent.h_name) |
| 295 | { |
| 296 | callback(arg, ARES_ENOMEM, 0, NULL); |
| 297 | return 1; |
| 298 | } |
| 299 | |
| 300 | /* Fill in the rest of the host structure and terminate the query. */ |
| 301 | addrs[1] = NULL; |
| 302 | hostent.h_aliases = aliases; |
| 303 | hostent.h_addrtype = family; |
| 304 | hostent.h_addr_list = addrs; |
| 305 | callback(arg, ARES_SUCCESS, 0, &hostent); |
| 306 | |
| 307 | free((char *)(hostent.h_name)); |
| 308 | return 1; |
| 309 | } |
| 310 | |
| 311 | /* This is an API method */ |
| 312 | int ares_gethostbyname_file(ares_channel channel, const char *name, |
| 313 | int family, struct hostent **host) |
| 314 | { |
| 315 | int result; |
| 316 | |
| 317 | /* We only take the channel to ensure that ares_init() been called. */ |
| 318 | if(channel == NULL) |
| 319 | { |
| 320 | /* Anything will do, really. This seems fine, and is consistent with |
| 321 | other error cases. */ |
| 322 | *host = NULL; |
| 323 | return ARES_ENOTFOUND; |
| 324 | } |
| 325 | |
| 326 | /* Just chain to the internal implementation we use here; it's exactly |
| 327 | * what we want. |
| 328 | */ |
| 329 | result = file_lookup(name, family, host); |
| 330 | if(result != ARES_SUCCESS) |
| 331 | { |
| 332 | /* We guarantee a NULL hostent on failure. */ |
| 333 | *host = NULL; |
| 334 | } |
| 335 | return result; |
| 336 | } |
| 337 | |
| 338 | static int file_lookup(const char *name, int family, struct hostent **host) |
| 339 | { |
| 340 | FILE *fp; |
| 341 | char **alias; |
| 342 | int status; |
| 343 | int error; |
| 344 | |
| 345 | #ifdef WIN32 |
| 346 | char PATH_HOSTS[MAX_PATH]; |
| 347 | win_platform platform; |
| 348 | |
| 349 | PATH_HOSTS[0] = '\0'; |
| 350 | |
| 351 | platform = ares__getplatform(); |
| 352 | |
| 353 | if (platform == WIN_NT) { |
| 354 | char tmp[MAX_PATH]; |
| 355 | HKEY hkeyHosts; |
| 356 | |
| 357 | if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ, |
| 358 | &hkeyHosts) == ERROR_SUCCESS) |
| 359 | { |
| 360 | DWORD dwLength = MAX_PATH; |
| 361 | RegQueryValueEx(hkeyHosts, DATABASEPATH, NULL, NULL, (LPBYTE)tmp, |
| 362 | &dwLength); |
| 363 | ExpandEnvironmentStrings(tmp, PATH_HOSTS, MAX_PATH); |
| 364 | RegCloseKey(hkeyHosts); |
| 365 | } |
| 366 | } |
| 367 | else if (platform == WIN_9X) |
| 368 | GetWindowsDirectory(PATH_HOSTS, MAX_PATH); |
| 369 | else |
| 370 | return ARES_ENOTFOUND; |
| 371 | |
| 372 | strcat(PATH_HOSTS, WIN_PATH_HOSTS); |
| 373 | |
| 374 | #elif defined(WATT32) |
| 375 | extern const char *_w32_GetHostsFile (void); |
| 376 | const char *PATH_HOSTS = _w32_GetHostsFile(); |
| 377 | |
| 378 | if (!PATH_HOSTS) |
| 379 | return ARES_ENOTFOUND; |
| 380 | #endif |
| 381 | |
| 382 | fp = fopen(PATH_HOSTS, "r"); |
| 383 | if (!fp) |
| 384 | { |
| 385 | error = ERRNO; |
| 386 | switch(error) |
| 387 | { |
| 388 | case ENOENT: |
| 389 | case ESRCH: |
| 390 | return ARES_ENOTFOUND; |
| 391 | default: |
| 392 | DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n", |
| 393 | error, strerror(error))); |
| 394 | DEBUGF(fprintf(stderr, "Error opening file: %s\n", |
| 395 | PATH_HOSTS)); |
| 396 | *host = NULL; |
| 397 | return ARES_EFILE; |
| 398 | } |
| 399 | } |
| 400 | while ((status = ares__get_hostent(fp, family, host)) == ARES_SUCCESS) |
| 401 | { |
| 402 | if (strcasecmp((*host)->h_name, name) == 0) |
| 403 | break; |
| 404 | for (alias = (*host)->h_aliases; *alias; alias++) |
| 405 | { |
| 406 | if (strcasecmp(*alias, name) == 0) |
| 407 | break; |
| 408 | } |
| 409 | if (*alias) |
| 410 | break; |
| 411 | ares_free_hostent(*host); |
| 412 | } |
| 413 | fclose(fp); |
| 414 | if (status == ARES_EOF) |
| 415 | status = ARES_ENOTFOUND; |
| 416 | if (status != ARES_SUCCESS) |
| 417 | *host = NULL; |
| 418 | return status; |
| 419 | } |
| 420 | |
| 421 | static void sort_addresses(struct hostent *host, |
| 422 | const struct apattern *sortlist, int nsort) |
| 423 | { |
| 424 | struct in_addr a1, a2; |
| 425 | int i1, i2, ind1, ind2; |
| 426 | |
| 427 | /* This is a simple insertion sort, not optimized at all. i1 walks |
| 428 | * through the address list, with the loop invariant that everything |
| 429 | * to the left of i1 is sorted. In the loop body, the value at i1 is moved |
| 430 | * back through the list (via i2) until it is in sorted order. |
| 431 | */ |
| 432 | for (i1 = 0; host->h_addr_list[i1]; i1++) |
| 433 | { |
| 434 | memcpy(&a1, host->h_addr_list[i1], sizeof(struct in_addr)); |
| 435 | ind1 = get_address_index(&a1, sortlist, nsort); |
| 436 | for (i2 = i1 - 1; i2 >= 0; i2--) |
| 437 | { |
| 438 | memcpy(&a2, host->h_addr_list[i2], sizeof(struct in_addr)); |
| 439 | ind2 = get_address_index(&a2, sortlist, nsort); |
| 440 | if (ind2 <= ind1) |
| 441 | break; |
| 442 | memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct in_addr)); |
| 443 | } |
| 444 | memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct in_addr)); |
| 445 | } |
| 446 | } |
| 447 | |
| 448 | /* Find the first entry in sortlist which matches addr. Return nsort |
| 449 | * if none of them match. |
| 450 | */ |
| 451 | static int get_address_index(const struct in_addr *addr, |
| 452 | const struct apattern *sortlist, |
| 453 | int nsort) |
| 454 | { |
| 455 | int i; |
| 456 | |
| 457 | for (i = 0; i < nsort; i++) |
| 458 | { |
| 459 | if (sortlist[i].family != AF_INET) |
| 460 | continue; |
| 461 | if (sortlist[i].type == PATTERN_MASK) |
| 462 | { |
| 463 | if ((addr->s_addr & sortlist[i].mask.addr4.s_addr) |
| 464 | == sortlist[i].addrV4.s_addr) |
| 465 | break; |
| 466 | } |
| 467 | else |
| 468 | { |
| 469 | if (!ares_bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr, |
| 470 | sortlist[i].mask.bits)) |
| 471 | break; |
| 472 | } |
| 473 | } |
| 474 | return i; |
| 475 | } |
| 476 | |
| 477 | static void sort6_addresses(struct hostent *host, |
| 478 | const struct apattern *sortlist, int nsort) |
| 479 | { |
| 480 | struct ares_in6_addr a1, a2; |
| 481 | int i1, i2, ind1, ind2; |
| 482 | |
| 483 | /* This is a simple insertion sort, not optimized at all. i1 walks |
| 484 | * through the address list, with the loop invariant that everything |
| 485 | * to the left of i1 is sorted. In the loop body, the value at i1 is moved |
| 486 | * back through the list (via i2) until it is in sorted order. |
| 487 | */ |
| 488 | for (i1 = 0; host->h_addr_list[i1]; i1++) |
| 489 | { |
| 490 | memcpy(&a1, host->h_addr_list[i1], sizeof(struct ares_in6_addr)); |
| 491 | ind1 = get6_address_index(&a1, sortlist, nsort); |
| 492 | for (i2 = i1 - 1; i2 >= 0; i2--) |
| 493 | { |
| 494 | memcpy(&a2, host->h_addr_list[i2], sizeof(struct ares_in6_addr)); |
| 495 | ind2 = get6_address_index(&a2, sortlist, nsort); |
| 496 | if (ind2 <= ind1) |
| 497 | break; |
| 498 | memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct ares_in6_addr)); |
| 499 | } |
| 500 | memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct ares_in6_addr)); |
| 501 | } |
| 502 | } |
| 503 | |
| 504 | /* Find the first entry in sortlist which matches addr. Return nsort |
| 505 | * if none of them match. |
| 506 | */ |
| 507 | static int get6_address_index(const struct ares_in6_addr *addr, |
| 508 | const struct apattern *sortlist, |
| 509 | int nsort) |
| 510 | { |
| 511 | int i; |
| 512 | |
| 513 | for (i = 0; i < nsort; i++) |
| 514 | { |
| 515 | if (sortlist[i].family != AF_INET6) |
| 516 | continue; |
| 517 | if (!ares_bitncmp(addr, |
| 518 | &sortlist[i].addrV6, |
| 519 | sortlist[i].mask.bits)) |
| 520 | break; |
| 521 | } |
| 522 | return i; |
| 523 | } |