2 /* Copyright 1998, 2011, 2013 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_NETINET_IN_H
20 # include <netinet/in.h>
25 #ifdef HAVE_ARPA_INET_H
26 # include <arpa/inet.h>
28 #ifdef HAVE_ARPA_NAMESER_H
29 # include <arpa/nameser.h>
33 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
34 # include <arpa/nameser_compat.h>
42 #include "ares_inet_net_pton.h"
44 #include "ares_platform.h"
45 #include "ares_nowarn.h"
46 #include "ares_private.h"
53 /* Arguments passed to ares_gethostbyname() */
56 ares_host_callback callback;
58 int sent_family; /* this family is what was is being used */
59 int want_family; /* this family is what is asked for in the API */
60 const char *remaining_lookups;
64 static void next_lookup(struct host_query *hquery, int status_code);
65 static void host_callback(void *arg, int status, int timeouts,
66 unsigned char *abuf, int alen);
67 static void end_hquery(struct host_query *hquery, int status,
68 struct hostent *host);
69 static int fake_hostent(const char *name, int family,
70 ares_host_callback callback, void *arg);
71 static int file_lookup(const char *name, int family, struct hostent **host);
72 static void sort_addresses(struct hostent *host,
73 const struct apattern *sortlist, int nsort);
74 static void sort6_addresses(struct hostent *host,
75 const struct apattern *sortlist, int nsort);
76 static int get_address_index(const struct in_addr *addr,
77 const struct apattern *sortlist, int nsort);
78 static int get6_address_index(const struct ares_in6_addr *addr,
79 const struct apattern *sortlist, int nsort);
81 void ares_gethostbyname(ares_channel channel, const char *name, int family,
82 ares_host_callback callback, void *arg)
84 struct host_query *hquery;
86 /* Right now we only know how to look up Internet addresses - and unspec
87 means try both basically. */
94 callback(arg, ARES_ENOTIMP, 0, NULL);
98 if (fake_hostent(name, family, callback, arg))
101 /* Allocate and fill in the host query structure. */
102 hquery = malloc(sizeof(struct host_query));
105 callback(arg, ARES_ENOMEM, 0, NULL);
108 hquery->channel = channel;
109 hquery->name = strdup(name);
110 hquery->want_family = family;
111 hquery->sent_family = -1; /* nothing is sent yet */
114 callback(arg, ARES_ENOMEM, 0, NULL);
117 hquery->callback = callback;
119 hquery->remaining_lookups = channel->lookups;
120 hquery->timeouts = 0;
122 /* Start performing lookups according to channel->lookups. */
123 next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */);
126 static void next_lookup(struct host_query *hquery, int status_code)
129 struct hostent *host;
130 int status = status_code;
132 for (p = hquery->remaining_lookups; *p; p++)
138 hquery->remaining_lookups = p + 1;
139 if ((hquery->want_family == AF_INET6) ||
140 (hquery->want_family == AF_UNSPEC)) {
141 /* if inet6 or unspec, start out with AAAA */
142 hquery->sent_family = AF_INET6;
143 ares_search(hquery->channel, hquery->name, C_IN, T_AAAA,
144 host_callback, hquery);
147 hquery->sent_family = AF_INET;
148 ares_search(hquery->channel, hquery->name, C_IN, T_A,
149 host_callback, hquery);
154 /* Host file lookup */
155 status = file_lookup(hquery->name, hquery->want_family, &host);
157 /* this status check below previously checked for !ARES_ENOTFOUND,
158 but we should not assume that this single error code is the one
159 that can occur, as that is in fact no longer the case */
160 if (status == ARES_SUCCESS)
162 end_hquery(hquery, status, host);
165 status = status_code; /* Use original status code */
169 end_hquery(hquery, status, NULL);
172 static void host_callback(void *arg, int status, int timeouts,
173 unsigned char *abuf, int alen)
175 struct host_query *hquery = (struct host_query *) arg;
176 ares_channel channel = hquery->channel;
177 struct hostent *host = NULL;
179 hquery->timeouts += timeouts;
180 if (status == ARES_SUCCESS)
182 if (hquery->sent_family == AF_INET)
184 status = ares_parse_a_reply(abuf, alen, &host, NULL, NULL);
185 if (host && channel->nsort)
186 sort_addresses(host, channel->sortlist, channel->nsort);
188 else if (hquery->sent_family == AF_INET6)
190 status = ares_parse_aaaa_reply(abuf, alen, &host, NULL, NULL);
191 if ((status == ARES_ENODATA || status == ARES_EBADRESP) &&
192 hquery->want_family == AF_UNSPEC) {
193 /* The query returned something but either there were no AAAA
194 records (e.g. just CNAME) or the response was malformed. Try
195 looking up A instead. */
196 hquery->sent_family = AF_INET;
197 ares_search(hquery->channel, hquery->name, C_IN, T_A,
198 host_callback, hquery);
201 if (host && channel->nsort)
202 sort6_addresses(host, channel->sortlist, channel->nsort);
204 end_hquery(hquery, status, host);
206 else if ((status == ARES_ENODATA || status == ARES_EBADRESP ||
207 status == ARES_ETIMEOUT) && (hquery->sent_family == AF_INET6 &&
208 hquery->want_family == AF_UNSPEC))
210 /* The AAAA query yielded no useful result. Now look up an A instead. */
211 hquery->sent_family = AF_INET;
212 ares_search(hquery->channel, hquery->name, C_IN, T_A, host_callback,
215 else if (status == ARES_EDESTRUCTION)
216 end_hquery(hquery, status, NULL);
218 next_lookup(hquery, status);
221 static void end_hquery(struct host_query *hquery, int status,
222 struct hostent *host)
224 hquery->callback(hquery->arg, status, hquery->timeouts, host);
226 ares_free_hostent(host);
231 /* If the name looks like an IP address, fake up a host entry, end the
232 * query immediately, and return true. Otherwise return false.
234 static int fake_hostent(const char *name, int family,
235 ares_host_callback callback, void *arg)
237 struct hostent hostent;
238 char *aliases[1] = { NULL };
242 struct ares_in6_addr in6;
244 if (family == AF_INET || family == AF_INET6)
246 /* It only looks like an IP address if it's all numbers and dots. */
247 int numdots = 0, valid = 1;
249 for (p = name; *p; p++)
251 if (!ISDIGIT(*p) && *p != '.') {
254 } else if (*p == '.') {
259 /* if we don't have 3 dots, it is illegal
260 * (although inet_addr doesn't think so).
262 if (numdots != 3 || !valid)
265 result = ((in.s_addr = inet_addr(name)) == INADDR_NONE ? 0 : 1);
270 if (family == AF_INET6)
271 result = (ares_inet_pton(AF_INET6, name, &in6) < 1 ? 0 : 1);
276 if (family == AF_INET)
278 hostent.h_length = (int)sizeof(struct in_addr);
279 addrs[0] = (char *)∈
281 else if (family == AF_INET6)
283 hostent.h_length = (int)sizeof(struct ares_in6_addr);
284 addrs[0] = (char *)&in6;
286 /* Duplicate the name, to avoid a constness violation. */
287 hostent.h_name = strdup(name);
290 callback(arg, ARES_ENOMEM, 0, NULL);
294 /* Fill in the rest of the host structure and terminate the query. */
296 hostent.h_aliases = aliases;
297 hostent.h_addrtype = aresx_sitoss(family);
298 hostent.h_addr_list = addrs;
299 callback(arg, ARES_SUCCESS, 0, &hostent);
301 free((char *)(hostent.h_name));
305 /* This is an API method */
306 int ares_gethostbyname_file(ares_channel channel, const char *name,
307 int family, struct hostent **host)
311 /* We only take the channel to ensure that ares_init() been called. */
314 /* Anything will do, really. This seems fine, and is consistent with
315 other error cases. */
317 return ARES_ENOTFOUND;
320 /* Just chain to the internal implementation we use here; it's exactly
323 result = file_lookup(name, family, host);
324 if(result != ARES_SUCCESS)
326 /* We guarantee a NULL hostent on failure. */
332 static int file_lookup(const char *name, int family, struct hostent **host)
340 char PATH_HOSTS[MAX_PATH];
341 win_platform platform;
343 PATH_HOSTS[0] = '\0';
345 platform = ares__getplatform();
347 if (platform == WIN_NT) {
351 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ,
352 &hkeyHosts) == ERROR_SUCCESS)
354 DWORD dwLength = MAX_PATH;
355 RegQueryValueEx(hkeyHosts, DATABASEPATH, NULL, NULL, (LPBYTE)tmp,
357 ExpandEnvironmentStrings(tmp, PATH_HOSTS, MAX_PATH);
358 RegCloseKey(hkeyHosts);
361 else if (platform == WIN_9X)
362 GetWindowsDirectory(PATH_HOSTS, MAX_PATH);
364 return ARES_ENOTFOUND;
366 strcat(PATH_HOSTS, WIN_PATH_HOSTS);
368 #elif defined(WATT32)
369 extern const char *_w32_GetHostsFile (void);
370 const char *PATH_HOSTS = _w32_GetHostsFile();
373 return ARES_ENOTFOUND;
376 fp = fopen(PATH_HOSTS, "r");
384 return ARES_ENOTFOUND;
386 DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n",
387 error, strerror(error)));
388 DEBUGF(fprintf(stderr, "Error opening file: %s\n",
394 while ((status = ares__get_hostent(fp, family, host)) == ARES_SUCCESS)
396 if (strcasecmp((*host)->h_name, name) == 0)
398 for (alias = (*host)->h_aliases; *alias; alias++)
400 if (strcasecmp(*alias, name) == 0)
405 ares_free_hostent(*host);
408 if (status == ARES_EOF)
409 status = ARES_ENOTFOUND;
410 if (status != ARES_SUCCESS)
415 static void sort_addresses(struct hostent *host,
416 const struct apattern *sortlist, int nsort)
418 struct in_addr a1, a2;
419 int i1, i2, ind1, ind2;
421 /* This is a simple insertion sort, not optimized at all. i1 walks
422 * through the address list, with the loop invariant that everything
423 * to the left of i1 is sorted. In the loop body, the value at i1 is moved
424 * back through the list (via i2) until it is in sorted order.
426 for (i1 = 0; host->h_addr_list[i1]; i1++)
428 memcpy(&a1, host->h_addr_list[i1], sizeof(struct in_addr));
429 ind1 = get_address_index(&a1, sortlist, nsort);
430 for (i2 = i1 - 1; i2 >= 0; i2--)
432 memcpy(&a2, host->h_addr_list[i2], sizeof(struct in_addr));
433 ind2 = get_address_index(&a2, sortlist, nsort);
436 memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct in_addr));
438 memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct in_addr));
442 /* Find the first entry in sortlist which matches addr. Return nsort
443 * if none of them match.
445 static int get_address_index(const struct in_addr *addr,
446 const struct apattern *sortlist,
451 for (i = 0; i < nsort; i++)
453 if (sortlist[i].family != AF_INET)
455 if (sortlist[i].type == PATTERN_MASK)
457 if ((addr->s_addr & sortlist[i].mask.addr4.s_addr)
458 == sortlist[i].addrV4.s_addr)
463 if (!ares__bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr,
464 sortlist[i].mask.bits))
471 static void sort6_addresses(struct hostent *host,
472 const struct apattern *sortlist, int nsort)
474 struct ares_in6_addr a1, a2;
475 int i1, i2, ind1, ind2;
477 /* This is a simple insertion sort, not optimized at all. i1 walks
478 * through the address list, with the loop invariant that everything
479 * to the left of i1 is sorted. In the loop body, the value at i1 is moved
480 * back through the list (via i2) until it is in sorted order.
482 for (i1 = 0; host->h_addr_list[i1]; i1++)
484 memcpy(&a1, host->h_addr_list[i1], sizeof(struct ares_in6_addr));
485 ind1 = get6_address_index(&a1, sortlist, nsort);
486 for (i2 = i1 - 1; i2 >= 0; i2--)
488 memcpy(&a2, host->h_addr_list[i2], sizeof(struct ares_in6_addr));
489 ind2 = get6_address_index(&a2, sortlist, nsort);
492 memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct ares_in6_addr));
494 memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct ares_in6_addr));
498 /* Find the first entry in sortlist which matches addr. Return nsort
499 * if none of them match.
501 static int get6_address_index(const struct ares_in6_addr *addr,
502 const struct apattern *sortlist,
507 for (i = 0; i < nsort; i++)
509 if (sortlist[i].family != AF_INET6)
511 if (!ares__bitncmp(addr, &sortlist[i].addrV6, sortlist[i].mask.bits))