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