2 /* Copyright 1998 by the Massachusetts Institute of Technology.
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.
17 #include "ares_setup.h"
19 #ifdef HAVE_SYS_SOCKET_H
20 # include <sys/socket.h>
22 #ifdef HAVE_NETINET_IN_H
23 # include <netinet/in.h>
28 #ifdef HAVE_ARPA_INET_H
29 # include <arpa/inet.h>
31 #ifdef HAVE_ARPA_NAMESER_H
32 # include <arpa/nameser.h>
36 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
37 # include <arpa/nameser_compat.h>
49 #include "inet_net_pton.h"
51 #include "ares_platform.h"
52 #include "ares_private.h"
59 /* Arguments passed to ares_gethostbyname() */
62 ares_host_callback callback;
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;
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);
87 void ares_gethostbyname(ares_channel channel, const char *name, int family,
88 ares_host_callback callback, void *arg)
90 struct host_query *hquery;
92 /* Right now we only know how to look up Internet addresses - and unspec
93 means try both basically. */
100 callback(arg, ARES_ENOTIMP, 0, NULL);
104 if (fake_hostent(name, family, callback, arg))
107 /* Allocate and fill in the host query structure. */
108 hquery = malloc(sizeof(struct host_query));
111 callback(arg, ARES_ENOMEM, 0, NULL);
114 hquery->channel = channel;
115 hquery->name = strdup(name);
116 hquery->want_family = family;
117 hquery->sent_family = -1; /* nothing is sent yet */
120 callback(arg, ARES_ENOMEM, 0, NULL);
123 hquery->callback = callback;
125 hquery->remaining_lookups = channel->lookups;
126 hquery->timeouts = 0;
128 /* Start performing lookups according to channel->lookups. */
129 next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */);
132 static void next_lookup(struct host_query *hquery, int status_code)
135 struct hostent *host;
136 int status = status_code;
138 for (p = hquery->remaining_lookups; *p; p++)
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);
153 hquery->sent_family = AF_INET;
154 ares_search(hquery->channel, hquery->name, C_IN, T_A,
155 host_callback, hquery);
160 /* Host file lookup */
161 status = file_lookup(hquery->name, hquery->want_family, &host);
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)
168 end_hquery(hquery, status, host);
171 status = status_code; /* Use original status code */
175 end_hquery(hquery, status, NULL);
178 static void host_callback(void *arg, int status, int timeouts,
179 unsigned char *abuf, int alen)
181 struct host_query *hquery = (struct host_query *) arg;
182 ares_channel channel = hquery->channel;
183 struct hostent *host = NULL;
185 hquery->timeouts += timeouts;
186 if (status == ARES_SUCCESS)
188 if (hquery->sent_family == AF_INET)
190 status = ares_parse_a_reply(abuf, alen, &host, NULL, NULL);
191 if (host && channel->nsort)
192 sort_addresses(host, channel->sortlist, channel->nsort);
194 else if (hquery->sent_family == AF_INET6)
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);
207 if (host && channel->nsort)
208 sort6_addresses(host, channel->sortlist, channel->nsort);
210 end_hquery(hquery, status, host);
212 else if ((status == ARES_ENODATA || status == ARES_EBADRESP ||
213 status == ARES_ETIMEOUT) && (hquery->sent_family == AF_INET6 &&
214 hquery->want_family == AF_UNSPEC))
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,
221 else if (status == ARES_EDESTRUCTION)
222 end_hquery(hquery, status, NULL);
224 next_lookup(hquery, status);
227 static void end_hquery(struct host_query *hquery, int status,
228 struct hostent *host)
230 hquery->callback(hquery->arg, status, hquery->timeouts, host);
232 ares_free_hostent(host);
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.
240 static int fake_hostent(const char *name, int family,
241 ares_host_callback callback, void *arg)
243 struct hostent hostent;
244 char *aliases[1] = { NULL };
248 struct ares_in6_addr in6;
250 if (family == AF_INET || family == AF_INET6)
252 /* It only looks like an IP address if it's all numbers and dots. */
253 int numdots = 0, valid = 1;
255 for (p = name; *p; p++)
257 if (!ISDIGIT(*p) && *p != '.') {
260 } else if (*p == '.') {
265 /* if we don't have 3 dots, it is illegal
266 * (although inet_addr doesn't think so).
268 if (numdots != 3 || !valid)
271 result = ((in.s_addr = inet_addr(name)) == INADDR_NONE ? 0 : 1);
276 if (family == AF_INET6)
277 result = (ares_inet_pton(AF_INET6, name, &in6) < 1 ? 0 : 1);
282 if (family == AF_INET)
284 hostent.h_length = (int)sizeof(struct in_addr);
285 addrs[0] = (char *)∈
287 else if (family == AF_INET6)
289 hostent.h_length = (int)sizeof(struct ares_in6_addr);
290 addrs[0] = (char *)&in6;
292 /* Duplicate the name, to avoid a constness violation. */
293 hostent.h_name = strdup(name);
296 callback(arg, ARES_ENOMEM, 0, NULL);
300 /* Fill in the rest of the host structure and terminate the query. */
302 hostent.h_aliases = aliases;
303 hostent.h_addrtype = family;
304 hostent.h_addr_list = addrs;
305 callback(arg, ARES_SUCCESS, 0, &hostent);
307 free((char *)(hostent.h_name));
311 /* This is an API method */
312 int ares_gethostbyname_file(ares_channel channel, const char *name,
313 int family, struct hostent **host)
317 /* We only take the channel to ensure that ares_init() been called. */
320 /* Anything will do, really. This seems fine, and is consistent with
321 other error cases. */
323 return ARES_ENOTFOUND;
326 /* Just chain to the internal implementation we use here; it's exactly
329 result = file_lookup(name, family, host);
330 if(result != ARES_SUCCESS)
332 /* We guarantee a NULL hostent on failure. */
338 static int file_lookup(const char *name, int family, struct hostent **host)
346 char PATH_HOSTS[MAX_PATH];
347 win_platform platform;
349 PATH_HOSTS[0] = '\0';
351 platform = ares__getplatform();
353 if (platform == WIN_NT) {
357 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ,
358 &hkeyHosts) == ERROR_SUCCESS)
360 DWORD dwLength = MAX_PATH;
361 RegQueryValueEx(hkeyHosts, DATABASEPATH, NULL, NULL, (LPBYTE)tmp,
363 ExpandEnvironmentStrings(tmp, PATH_HOSTS, MAX_PATH);
364 RegCloseKey(hkeyHosts);
367 else if (platform == WIN_9X)
368 GetWindowsDirectory(PATH_HOSTS, MAX_PATH);
370 return ARES_ENOTFOUND;
372 strcat(PATH_HOSTS, WIN_PATH_HOSTS);
374 #elif defined(WATT32)
375 extern const char *_w32_GetHostsFile (void);
376 const char *PATH_HOSTS = _w32_GetHostsFile();
379 return ARES_ENOTFOUND;
382 fp = fopen(PATH_HOSTS, "r");
390 return ARES_ENOTFOUND;
392 DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n",
393 error, strerror(error)));
394 DEBUGF(fprintf(stderr, "Error opening file: %s\n",
400 while ((status = ares__get_hostent(fp, family, host)) == ARES_SUCCESS)
402 if (strcasecmp((*host)->h_name, name) == 0)
404 for (alias = (*host)->h_aliases; *alias; alias++)
406 if (strcasecmp(*alias, name) == 0)
411 ares_free_hostent(*host);
414 if (status == ARES_EOF)
415 status = ARES_ENOTFOUND;
416 if (status != ARES_SUCCESS)
421 static void sort_addresses(struct hostent *host,
422 const struct apattern *sortlist, int nsort)
424 struct in_addr a1, a2;
425 int i1, i2, ind1, ind2;
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.
432 for (i1 = 0; host->h_addr_list[i1]; i1++)
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--)
438 memcpy(&a2, host->h_addr_list[i2], sizeof(struct in_addr));
439 ind2 = get_address_index(&a2, sortlist, nsort);
442 memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct in_addr));
444 memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct in_addr));
448 /* Find the first entry in sortlist which matches addr. Return nsort
449 * if none of them match.
451 static int get_address_index(const struct in_addr *addr,
452 const struct apattern *sortlist,
457 for (i = 0; i < nsort; i++)
459 if (sortlist[i].family != AF_INET)
461 if (sortlist[i].type == PATTERN_MASK)
463 if ((addr->s_addr & sortlist[i].mask.addr4.s_addr)
464 == sortlist[i].addrV4.s_addr)
469 if (!ares_bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr,
470 sortlist[i].mask.bits))
477 static void sort6_addresses(struct hostent *host,
478 const struct apattern *sortlist, int nsort)
480 struct ares_in6_addr a1, a2;
481 int i1, i2, ind1, ind2;
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.
488 for (i1 = 0; host->h_addr_list[i1]; i1++)
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--)
494 memcpy(&a2, host->h_addr_list[i2], sizeof(struct ares_in6_addr));
495 ind2 = get6_address_index(&a2, sortlist, nsort);
498 memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct ares_in6_addr));
500 memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct ares_in6_addr));
504 /* Find the first entry in sortlist which matches addr. Return nsort
505 * if none of them match.
507 static int get6_address_index(const struct ares_in6_addr *addr,
508 const struct apattern *sortlist,
513 for (i = 0; i < nsort; i++)
515 if (sortlist[i].family != AF_INET6)
517 if (!ares_bitncmp(addr,
519 sortlist[i].mask.bits))