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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
dd0bc0f1 LP |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2016 Lennart Poettering | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
21 | #include "fd-util.h" | |
22 | #include "fileio.h" | |
23 | #include "hostname-util.h" | |
24 | #include "resolved-etc-hosts.h" | |
25 | #include "resolved-dns-synthesize.h" | |
26 | #include "string-util.h" | |
27 | #include "strv.h" | |
28 | #include "time-util.h" | |
29 | ||
30 | /* Recheck /etc/hosts at most once every 2s */ | |
31 | #define ETC_HOSTS_RECHECK_USEC (2*USEC_PER_SEC) | |
32 | ||
33 | typedef struct EtcHostsItem { | |
34 | int family; | |
35 | union in_addr_union address; | |
36 | ||
37 | char **names; | |
38 | } EtcHostsItem; | |
39 | ||
40 | typedef struct EtcHostsItemByName { | |
41 | char *name; | |
42 | ||
43 | EtcHostsItem **items; | |
44 | size_t n_items, n_allocated; | |
45 | } EtcHostsItemByName; | |
46 | ||
47 | void manager_etc_hosts_flush(Manager *m) { | |
48 | EtcHostsItem *item; | |
49 | EtcHostsItemByName *bn; | |
50 | ||
51 | while ((item = set_steal_first(m->etc_hosts_by_address))) { | |
52 | strv_free(item->names); | |
53 | free(item); | |
54 | } | |
55 | ||
56 | while ((bn = hashmap_steal_first(m->etc_hosts_by_name))) { | |
57 | free(bn->name); | |
58 | free(bn->items); | |
59 | free(bn); | |
60 | } | |
61 | ||
62 | m->etc_hosts_by_address = set_free(m->etc_hosts_by_address); | |
63 | m->etc_hosts_by_name = hashmap_free(m->etc_hosts_by_name); | |
64 | ||
65 | m->etc_hosts_mtime = USEC_INFINITY; | |
66 | } | |
67 | ||
68 | static void etc_hosts_item_hash_func(const void *p, struct siphash *state) { | |
69 | const EtcHostsItem *item = p; | |
70 | ||
71 | siphash24_compress(&item->family, sizeof(item->family), state); | |
72 | ||
73 | if (item->family == AF_INET) | |
74 | siphash24_compress(&item->address.in, sizeof(item->address.in), state); | |
75 | else if (item->family == AF_INET6) | |
76 | siphash24_compress(&item->address.in6, sizeof(item->address.in6), state); | |
77 | } | |
78 | ||
79 | static int etc_hosts_item_compare_func(const void *a, const void *b) { | |
80 | const EtcHostsItem *x = a, *y = b; | |
81 | ||
ec76e139 | 82 | if (x->family != y->family) |
dd0bc0f1 LP |
83 | return x->family - y->family; |
84 | ||
85 | if (x->family == AF_INET) | |
86 | return memcmp(&x->address.in.s_addr, &y->address.in.s_addr, sizeof(struct in_addr)); | |
87 | ||
88 | if (x->family == AF_INET6) | |
89 | return memcmp(&x->address.in6.s6_addr, &y->address.in6.s6_addr, sizeof(struct in6_addr)); | |
90 | ||
91 | return trivial_compare_func(a, b); | |
92 | } | |
93 | ||
94 | static const struct hash_ops etc_hosts_item_ops = { | |
95 | .hash = etc_hosts_item_hash_func, | |
96 | .compare = etc_hosts_item_compare_func, | |
97 | }; | |
98 | ||
99 | static int add_item(Manager *m, int family, const union in_addr_union *address, char **names) { | |
100 | ||
101 | EtcHostsItem key = { | |
102 | .family = family, | |
103 | .address = *address, | |
104 | }; | |
105 | EtcHostsItem *item; | |
106 | char **n; | |
107 | int r; | |
108 | ||
109 | assert(m); | |
110 | assert(address); | |
111 | ||
112 | r = in_addr_is_null(family, address); | |
113 | if (r < 0) | |
114 | return r; | |
115 | if (r > 0) | |
116 | /* This is an 0.0.0.0 or :: item, which we assume means that we shall map the specified hostname to | |
117 | * nothing. */ | |
118 | item = NULL; | |
119 | else { | |
120 | /* If this is a normal address, then, simply add entry mapping it to the specified names */ | |
121 | ||
122 | item = set_get(m->etc_hosts_by_address, &key); | |
123 | if (item) { | |
124 | r = strv_extend_strv(&item->names, names, true); | |
125 | if (r < 0) | |
126 | return log_oom(); | |
127 | } else { | |
128 | ||
129 | r = set_ensure_allocated(&m->etc_hosts_by_address, &etc_hosts_item_ops); | |
130 | if (r < 0) | |
131 | return log_oom(); | |
132 | ||
133 | item = new0(EtcHostsItem, 1); | |
134 | if (!item) | |
135 | return log_oom(); | |
136 | ||
137 | item->family = family; | |
138 | item->address = *address; | |
139 | item->names = names; | |
140 | ||
141 | r = set_put(m->etc_hosts_by_address, item); | |
142 | if (r < 0) { | |
143 | free(item); | |
144 | return log_oom(); | |
145 | } | |
146 | } | |
147 | } | |
148 | ||
149 | STRV_FOREACH(n, names) { | |
150 | EtcHostsItemByName *bn; | |
151 | ||
152 | bn = hashmap_get(m->etc_hosts_by_name, *n); | |
153 | if (!bn) { | |
154 | r = hashmap_ensure_allocated(&m->etc_hosts_by_name, &dns_name_hash_ops); | |
155 | if (r < 0) | |
156 | return log_oom(); | |
157 | ||
158 | bn = new0(EtcHostsItemByName, 1); | |
159 | if (!bn) | |
160 | return log_oom(); | |
161 | ||
162 | bn->name = strdup(*n); | |
163 | if (!bn->name) { | |
164 | free(bn); | |
165 | return log_oom(); | |
166 | } | |
167 | ||
168 | r = hashmap_put(m->etc_hosts_by_name, bn->name, bn); | |
169 | if (r < 0) { | |
170 | free(bn->name); | |
171 | free(bn); | |
172 | return log_oom(); | |
173 | } | |
174 | } | |
175 | ||
176 | if (item) { | |
177 | if (!GREEDY_REALLOC(bn->items, bn->n_allocated, bn->n_items+1)) | |
178 | return log_oom(); | |
179 | ||
180 | bn->items[bn->n_items++] = item; | |
181 | } | |
182 | } | |
183 | ||
184 | return 0; | |
185 | } | |
186 | ||
187 | static int parse_line(Manager *m, unsigned nr, const char *line) { | |
188 | _cleanup_free_ char *address = NULL; | |
189 | _cleanup_strv_free_ char **names = NULL; | |
190 | union in_addr_union in; | |
191 | bool suppressed = false; | |
192 | int family, r; | |
193 | ||
194 | assert(m); | |
195 | assert(line); | |
196 | ||
197 | r = extract_first_word(&line, &address, NULL, EXTRACT_RELAX); | |
198 | if (r < 0) | |
199 | return log_error_errno(r, "Couldn't extract address, in line /etc/hosts:%u.", nr); | |
200 | if (r == 0) { | |
201 | log_error("Premature end of line, in line /etc/hosts:%u.", nr); | |
202 | return -EINVAL; | |
203 | } | |
204 | ||
205 | r = in_addr_from_string_auto(address, &family, &in); | |
206 | if (r < 0) | |
207 | return log_error_errno(r, "Address '%s' is invalid, in line /etc/hosts:%u.", address, nr); | |
208 | ||
209 | for (;;) { | |
210 | _cleanup_free_ char *name = NULL; | |
211 | ||
212 | r = extract_first_word(&line, &name, NULL, EXTRACT_RELAX); | |
213 | if (r < 0) | |
214 | return log_error_errno(r, "Couldn't extract host name, in line /etc/hosts:%u.", nr); | |
215 | if (r == 0) | |
216 | break; | |
217 | ||
218 | r = dns_name_is_valid(name); | |
219 | if (r <= 0) | |
220 | return log_error_errno(r, "Hostname %s is not valid, ignoring, in line /etc/hosts:%u.", name, nr); | |
221 | ||
222 | if (is_localhost(name)) { | |
223 | /* Suppress the "localhost" line that is often seen */ | |
224 | suppressed = true; | |
225 | continue; | |
226 | } | |
227 | ||
228 | r = strv_push(&names, name); | |
229 | if (r < 0) | |
230 | return log_oom(); | |
231 | ||
232 | name = NULL; | |
233 | } | |
234 | ||
235 | if (strv_isempty(names)) { | |
236 | ||
237 | if (suppressed) | |
238 | return 0; | |
239 | ||
240 | log_error("Line is missing any host names, in line /etc/hosts:%u.", nr); | |
241 | return -EINVAL; | |
242 | } | |
243 | ||
244 | /* Takes possession of the names strv */ | |
245 | r = add_item(m, family, &in, names); | |
246 | if (r < 0) | |
247 | return r; | |
248 | ||
249 | names = NULL; | |
250 | return r; | |
251 | } | |
252 | ||
253 | int manager_etc_hosts_read(Manager *m) { | |
254 | _cleanup_fclose_ FILE *f = NULL; | |
255 | char line[LINE_MAX]; | |
256 | struct stat st; | |
257 | usec_t ts; | |
258 | unsigned nr = 0; | |
259 | int r; | |
260 | ||
261 | assert_se(sd_event_now(m->event, clock_boottime_or_monotonic(), &ts) >= 0); | |
262 | ||
263 | /* See if we checked /etc/hosts recently already */ | |
264 | if (m->etc_hosts_last != USEC_INFINITY && m->etc_hosts_last + ETC_HOSTS_RECHECK_USEC > ts) | |
265 | return 0; | |
266 | ||
267 | m->etc_hosts_last = ts; | |
268 | ||
269 | if (m->etc_hosts_mtime != USEC_INFINITY) { | |
270 | if (stat("/etc/hosts", &st) < 0) { | |
271 | if (errno == ENOENT) { | |
272 | r = 0; | |
273 | goto clear; | |
274 | } | |
275 | ||
276 | return log_error_errno(errno, "Failed to stat /etc/hosts: %m"); | |
277 | } | |
278 | ||
279 | /* Did the mtime change? If not, there's no point in re-reading the file. */ | |
280 | if (timespec_load(&st.st_mtim) == m->etc_hosts_mtime) | |
281 | return 0; | |
282 | } | |
283 | ||
284 | f = fopen("/etc/hosts", "re"); | |
285 | if (!f) { | |
286 | if (errno == ENOENT) { | |
287 | r = 0; | |
288 | goto clear; | |
289 | } | |
290 | ||
291 | return log_error_errno(errno, "Failed to open /etc/hosts: %m"); | |
292 | } | |
293 | ||
294 | /* Take the timestamp at the beginning of processing, so that any changes made later are read on the next | |
295 | * invocation */ | |
296 | r = fstat(fileno(f), &st); | |
297 | if (r < 0) | |
298 | return log_error_errno(errno, "Failed to fstat() /etc/hosts: %m"); | |
299 | ||
300 | manager_etc_hosts_flush(m); | |
301 | ||
302 | FOREACH_LINE(line, f, return log_error_errno(errno, "Failed to read /etc/hosts: %m")) { | |
303 | char *l; | |
304 | ||
313cefa1 | 305 | nr++; |
dd0bc0f1 LP |
306 | |
307 | l = strstrip(line); | |
308 | if (isempty(l)) | |
309 | continue; | |
310 | if (l[0] == '#') | |
311 | continue; | |
312 | ||
313 | r = parse_line(m, nr, l); | |
314 | if (r == -ENOMEM) /* On OOM we abandon the half-built-up structure. All other errors we ignore and proceed */ | |
315 | goto clear; | |
316 | } | |
317 | ||
318 | m->etc_hosts_mtime = timespec_load(&st.st_mtim); | |
319 | m->etc_hosts_last = ts; | |
320 | ||
321 | return 1; | |
322 | ||
323 | clear: | |
324 | manager_etc_hosts_flush(m); | |
325 | return r; | |
326 | } | |
327 | ||
328 | int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) { | |
329 | bool found_a = false, found_aaaa = false; | |
330 | EtcHostsItemByName *bn; | |
331 | EtcHostsItem k = {}; | |
332 | DnsResourceKey *t; | |
333 | const char *name; | |
334 | unsigned i; | |
335 | int r; | |
336 | ||
337 | assert(m); | |
338 | assert(q); | |
339 | assert(answer); | |
340 | ||
341 | r = manager_etc_hosts_read(m); | |
342 | if (r < 0) | |
343 | return r; | |
344 | ||
345 | name = dns_question_first_name(q); | |
346 | if (!name) | |
347 | return 0; | |
348 | ||
349 | r = dns_name_address(name, &k.family, &k.address); | |
350 | if (r > 0) { | |
351 | EtcHostsItem *item; | |
352 | DnsResourceKey *found_ptr = NULL; | |
353 | ||
354 | item = set_get(m->etc_hosts_by_address, &k); | |
355 | if (!item) | |
356 | return 0; | |
357 | ||
358 | /* We have an address in /etc/hosts that matches the queried name. Let's return successful. Actual data | |
359 | * we'll only return if the request was for PTR. */ | |
360 | ||
361 | DNS_QUESTION_FOREACH(t, q) { | |
362 | if (!IN_SET(t->type, DNS_TYPE_PTR, DNS_TYPE_ANY)) | |
363 | continue; | |
364 | if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY)) | |
365 | continue; | |
366 | ||
1c02e7ba | 367 | r = dns_name_equal(dns_resource_key_name(t), name); |
dd0bc0f1 LP |
368 | if (r < 0) |
369 | return r; | |
370 | if (r > 0) { | |
371 | found_ptr = t; | |
372 | break; | |
373 | } | |
374 | } | |
375 | ||
376 | if (found_ptr) { | |
377 | char **n; | |
378 | ||
379 | r = dns_answer_reserve(answer, strv_length(item->names)); | |
380 | if (r < 0) | |
381 | return r; | |
382 | ||
383 | STRV_FOREACH(n, item->names) { | |
384 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
385 | ||
386 | rr = dns_resource_record_new(found_ptr); | |
387 | if (!rr) | |
388 | return -ENOMEM; | |
389 | ||
390 | rr->ptr.name = strdup(*n); | |
391 | if (!rr->ptr.name) | |
392 | return -ENOMEM; | |
393 | ||
394 | r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED); | |
395 | if (r < 0) | |
396 | return r; | |
397 | } | |
398 | } | |
399 | ||
400 | return 1; | |
401 | } | |
402 | ||
403 | bn = hashmap_get(m->etc_hosts_by_name, name); | |
404 | if (!bn) | |
405 | return 0; | |
406 | ||
407 | r = dns_answer_reserve(answer, bn->n_items); | |
408 | if (r < 0) | |
409 | return r; | |
410 | ||
411 | DNS_QUESTION_FOREACH(t, q) { | |
412 | if (!IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_AAAA, DNS_TYPE_ANY)) | |
413 | continue; | |
414 | if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY)) | |
415 | continue; | |
416 | ||
1c02e7ba | 417 | r = dns_name_equal(dns_resource_key_name(t), name); |
dd0bc0f1 LP |
418 | if (r < 0) |
419 | return r; | |
420 | if (r == 0) | |
421 | continue; | |
422 | ||
423 | if (IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_ANY)) | |
424 | found_a = true; | |
425 | if (IN_SET(t->type, DNS_TYPE_AAAA, DNS_TYPE_ANY)) | |
426 | found_aaaa = true; | |
427 | ||
428 | if (found_a && found_aaaa) | |
429 | break; | |
430 | } | |
431 | ||
432 | for (i = 0; i < bn->n_items; i++) { | |
433 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
434 | ||
4050e04b MP |
435 | if ((!found_a && bn->items[i]->family == AF_INET) || |
436 | (!found_aaaa && bn->items[i]->family == AF_INET6)) | |
dd0bc0f1 LP |
437 | continue; |
438 | ||
439 | r = dns_resource_record_new_address(&rr, bn->items[i]->family, &bn->items[i]->address, bn->name); | |
440 | if (r < 0) | |
441 | return r; | |
442 | ||
443 | r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED); | |
444 | if (r < 0) | |
445 | return r; | |
446 | } | |
447 | ||
4050e04b | 448 | return found_a || found_aaaa; |
dd0bc0f1 | 449 | } |