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839a4a20 LP |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2014 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 "alloc-util.h" | |
21 | #include "hostname-util.h" | |
22 | #include "local-addresses.h" | |
23 | #include "resolved-dns-synthesize.h" | |
24 | ||
dd0bc0f1 | 25 | int dns_synthesize_ifindex(int ifindex) { |
839a4a20 LP |
26 | |
27 | /* When the caller asked for resolving on a specific | |
28 | * interface, we synthesize the answer for that | |
29 | * interface. However, if nothing specific was claimed and we | |
30 | * only return localhost RRs, we synthesize the answer for | |
31 | * localhost. */ | |
32 | ||
33 | if (ifindex > 0) | |
34 | return ifindex; | |
35 | ||
36 | return LOOPBACK_IFINDEX; | |
37 | } | |
38 | ||
dd0bc0f1 | 39 | int dns_synthesize_family(uint64_t flags) { |
839a4a20 LP |
40 | |
41 | /* Picks an address family depending on set flags. This is | |
42 | * purely for synthesized answers, where the family we return | |
43 | * for the reply should match what was requested in the | |
44 | * question, even though we are synthesizing the answer | |
45 | * here. */ | |
46 | ||
47 | if (!(flags & SD_RESOLVED_DNS)) { | |
48 | if (flags & (SD_RESOLVED_LLMNR_IPV4|SD_RESOLVED_MDNS_IPV4)) | |
49 | return AF_INET; | |
50 | if (flags & (SD_RESOLVED_LLMNR_IPV6|SD_RESOLVED_MDNS_IPV6)) | |
51 | return AF_INET6; | |
52 | } | |
53 | ||
54 | return AF_UNSPEC; | |
55 | } | |
56 | ||
dd0bc0f1 | 57 | DnsProtocol dns_synthesize_protocol(uint64_t flags) { |
839a4a20 | 58 | |
dd0bc0f1 | 59 | /* Similar as dns_synthesize_family() but does this for the |
839a4a20 LP |
60 | * protocol. If resolving via DNS was requested, we claim it |
61 | * was DNS. Similar, if nothing specific was | |
62 | * requested. However, if only resolving via LLMNR was | |
63 | * requested we return that. */ | |
64 | ||
65 | if (flags & SD_RESOLVED_DNS) | |
66 | return DNS_PROTOCOL_DNS; | |
67 | if (flags & SD_RESOLVED_LLMNR) | |
68 | return DNS_PROTOCOL_LLMNR; | |
69 | if (flags & SD_RESOLVED_MDNS) | |
70 | return DNS_PROTOCOL_MDNS; | |
71 | ||
72 | return DNS_PROTOCOL_DNS; | |
73 | } | |
74 | ||
75 | static int synthesize_localhost_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) { | |
76 | int r; | |
77 | ||
78 | assert(m); | |
79 | assert(key); | |
80 | assert(answer); | |
81 | ||
82 | r = dns_answer_reserve(answer, 2); | |
83 | if (r < 0) | |
84 | return r; | |
85 | ||
86 | if (IN_SET(key->type, DNS_TYPE_A, DNS_TYPE_ANY)) { | |
87 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
88 | ||
1c02e7ba | 89 | rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, dns_resource_key_name(key)); |
839a4a20 LP |
90 | if (!rr) |
91 | return -ENOMEM; | |
92 | ||
93 | rr->a.in_addr.s_addr = htobe32(INADDR_LOOPBACK); | |
94 | ||
dd0bc0f1 | 95 | r = dns_answer_add(*answer, rr, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED); |
839a4a20 LP |
96 | if (r < 0) |
97 | return r; | |
98 | } | |
99 | ||
100 | if (IN_SET(key->type, DNS_TYPE_AAAA, DNS_TYPE_ANY)) { | |
101 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
102 | ||
1c02e7ba | 103 | rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_AAAA, dns_resource_key_name(key)); |
839a4a20 LP |
104 | if (!rr) |
105 | return -ENOMEM; | |
106 | ||
107 | rr->aaaa.in6_addr = in6addr_loopback; | |
108 | ||
dd0bc0f1 | 109 | r = dns_answer_add(*answer, rr, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED); |
839a4a20 LP |
110 | if (r < 0) |
111 | return r; | |
112 | } | |
113 | ||
114 | return 0; | |
115 | } | |
116 | ||
117 | static int answer_add_ptr(DnsAnswer **answer, const char *from, const char *to, int ifindex, DnsAnswerFlags flags) { | |
118 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
119 | ||
120 | rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, from); | |
121 | if (!rr) | |
122 | return -ENOMEM; | |
123 | ||
124 | rr->ptr.name = strdup(to); | |
125 | if (!rr->ptr.name) | |
126 | return -ENOMEM; | |
127 | ||
128 | return dns_answer_add(*answer, rr, ifindex, flags); | |
129 | } | |
130 | ||
131 | static int synthesize_localhost_ptr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) { | |
132 | int r; | |
133 | ||
134 | assert(m); | |
135 | assert(key); | |
136 | assert(answer); | |
137 | ||
138 | if (IN_SET(key->type, DNS_TYPE_PTR, DNS_TYPE_ANY)) { | |
139 | r = dns_answer_reserve(answer, 1); | |
140 | if (r < 0) | |
141 | return r; | |
142 | ||
1c02e7ba | 143 | r = answer_add_ptr(answer, dns_resource_key_name(key), "localhost", dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED); |
839a4a20 LP |
144 | if (r < 0) |
145 | return r; | |
146 | } | |
147 | ||
148 | return 0; | |
149 | } | |
150 | ||
151 | static int answer_add_addresses_rr( | |
152 | DnsAnswer **answer, | |
153 | const char *name, | |
154 | struct local_address *addresses, | |
155 | unsigned n_addresses) { | |
156 | ||
157 | unsigned j; | |
158 | int r; | |
159 | ||
160 | assert(answer); | |
161 | assert(name); | |
162 | ||
163 | r = dns_answer_reserve(answer, n_addresses); | |
164 | if (r < 0) | |
165 | return r; | |
166 | ||
167 | for (j = 0; j < n_addresses; j++) { | |
168 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
169 | ||
170 | r = dns_resource_record_new_address(&rr, addresses[j].family, &addresses[j].address, name); | |
171 | if (r < 0) | |
172 | return r; | |
173 | ||
174 | r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED); | |
175 | if (r < 0) | |
176 | return r; | |
177 | } | |
178 | ||
179 | return 0; | |
180 | } | |
181 | ||
182 | static int answer_add_addresses_ptr( | |
183 | DnsAnswer **answer, | |
184 | const char *name, | |
185 | struct local_address *addresses, | |
186 | unsigned n_addresses, | |
187 | int af, const union in_addr_union *match) { | |
188 | ||
189 | unsigned j; | |
190 | int r; | |
191 | ||
192 | assert(answer); | |
193 | assert(name); | |
194 | ||
195 | for (j = 0; j < n_addresses; j++) { | |
196 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
197 | ||
198 | if (af != AF_UNSPEC) { | |
199 | ||
200 | if (addresses[j].family != af) | |
201 | continue; | |
202 | ||
203 | if (match && !in_addr_equal(af, match, &addresses[j].address)) | |
204 | continue; | |
205 | } | |
206 | ||
207 | r = dns_answer_reserve(answer, 1); | |
208 | if (r < 0) | |
209 | return r; | |
210 | ||
211 | r = dns_resource_record_new_reverse(&rr, addresses[j].family, &addresses[j].address, name); | |
212 | if (r < 0) | |
213 | return r; | |
214 | ||
215 | r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED); | |
216 | if (r < 0) | |
217 | return r; | |
218 | } | |
219 | ||
220 | return 0; | |
221 | } | |
222 | ||
223 | static int synthesize_system_hostname_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) { | |
224 | _cleanup_free_ struct local_address *addresses = NULL; | |
225 | int n = 0, af; | |
226 | ||
227 | assert(m); | |
228 | assert(key); | |
229 | assert(answer); | |
230 | ||
231 | af = dns_type_to_af(key->type); | |
232 | if (af >= 0) { | |
233 | n = local_addresses(m->rtnl, ifindex, af, &addresses); | |
234 | if (n < 0) | |
235 | return n; | |
236 | ||
237 | if (n == 0) { | |
238 | struct local_address buffer[2]; | |
239 | ||
240 | /* If we have no local addresses then use ::1 | |
241 | * and 127.0.0.2 as local ones. */ | |
242 | ||
243 | if (af == AF_INET || af == AF_UNSPEC) | |
244 | buffer[n++] = (struct local_address) { | |
245 | .family = AF_INET, | |
dd0bc0f1 | 246 | .ifindex = dns_synthesize_ifindex(ifindex), |
839a4a20 LP |
247 | .address.in.s_addr = htobe32(0x7F000002), |
248 | }; | |
249 | ||
250 | if (af == AF_INET6 || af == AF_UNSPEC) | |
251 | buffer[n++] = (struct local_address) { | |
252 | .family = AF_INET6, | |
dd0bc0f1 | 253 | .ifindex = dns_synthesize_ifindex(ifindex), |
839a4a20 LP |
254 | .address.in6 = in6addr_loopback, |
255 | }; | |
256 | ||
1c02e7ba | 257 | return answer_add_addresses_rr(answer, dns_resource_key_name(key), buffer, n); |
839a4a20 LP |
258 | } |
259 | } | |
260 | ||
1c02e7ba | 261 | return answer_add_addresses_rr(answer, dns_resource_key_name(key), addresses, n); |
839a4a20 LP |
262 | } |
263 | ||
264 | static int synthesize_system_hostname_ptr(Manager *m, int af, const union in_addr_union *address, int ifindex, DnsAnswer **answer) { | |
265 | _cleanup_free_ struct local_address *addresses = NULL; | |
266 | int n, r; | |
267 | ||
268 | assert(m); | |
269 | assert(address); | |
270 | assert(answer); | |
271 | ||
272 | if (af == AF_INET && address->in.s_addr == htobe32(0x7F000002)) { | |
273 | ||
274 | /* Always map the IPv4 address 127.0.0.2 to the local | |
275 | * hostname, in addition to "localhost": */ | |
276 | ||
277 | r = dns_answer_reserve(answer, 3); | |
278 | if (r < 0) | |
279 | return r; | |
280 | ||
dd0bc0f1 | 281 | r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", m->llmnr_hostname, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED); |
839a4a20 LP |
282 | if (r < 0) |
283 | return r; | |
284 | ||
dd0bc0f1 | 285 | r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", m->mdns_hostname, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED); |
839a4a20 LP |
286 | if (r < 0) |
287 | return r; | |
288 | ||
dd0bc0f1 | 289 | r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", "localhost", dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED); |
839a4a20 LP |
290 | if (r < 0) |
291 | return r; | |
292 | ||
293 | return 0; | |
294 | } | |
295 | ||
296 | n = local_addresses(m->rtnl, ifindex, af, &addresses); | |
297 | if (n < 0) | |
298 | return n; | |
299 | ||
300 | r = answer_add_addresses_ptr(answer, m->llmnr_hostname, addresses, n, af, address); | |
301 | if (r < 0) | |
302 | return r; | |
303 | ||
304 | return answer_add_addresses_ptr(answer, m->mdns_hostname, addresses, n, af, address); | |
305 | } | |
306 | ||
307 | static int synthesize_gateway_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) { | |
308 | _cleanup_free_ struct local_address *addresses = NULL; | |
309 | int n = 0, af; | |
310 | ||
311 | assert(m); | |
312 | assert(key); | |
313 | assert(answer); | |
314 | ||
315 | af = dns_type_to_af(key->type); | |
316 | if (af >= 0) { | |
317 | n = local_gateways(m->rtnl, ifindex, af, &addresses); | |
318 | if (n < 0) | |
319 | return n; | |
320 | } | |
321 | ||
1c02e7ba | 322 | return answer_add_addresses_rr(answer, dns_resource_key_name(key), addresses, n); |
839a4a20 LP |
323 | } |
324 | ||
325 | static int synthesize_gateway_ptr(Manager *m, int af, const union in_addr_union *address, int ifindex, DnsAnswer **answer) { | |
326 | _cleanup_free_ struct local_address *addresses = NULL; | |
327 | int n; | |
328 | ||
329 | assert(m); | |
330 | assert(address); | |
331 | assert(answer); | |
332 | ||
333 | n = local_gateways(m->rtnl, ifindex, af, &addresses); | |
334 | if (n < 0) | |
335 | return n; | |
336 | ||
337 | return answer_add_addresses_ptr(answer, "gateway", addresses, n, af, address); | |
338 | } | |
339 | ||
340 | int dns_synthesize_answer( | |
341 | Manager *m, | |
342 | DnsQuestion *q, | |
343 | int ifindex, | |
dd0bc0f1 | 344 | DnsAnswer **ret) { |
839a4a20 LP |
345 | |
346 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; | |
347 | DnsResourceKey *key; | |
528e685e | 348 | bool found = false; |
839a4a20 LP |
349 | int r; |
350 | ||
351 | assert(m); | |
352 | assert(q); | |
353 | ||
354 | DNS_QUESTION_FOREACH(key, q) { | |
355 | union in_addr_union address; | |
356 | const char *name; | |
357 | int af; | |
358 | ||
359 | if (key->class != DNS_CLASS_IN && | |
360 | key->class != DNS_CLASS_ANY) | |
361 | continue; | |
362 | ||
1c02e7ba | 363 | name = dns_resource_key_name(key); |
839a4a20 LP |
364 | |
365 | if (is_localhost(name)) { | |
366 | ||
367 | r = synthesize_localhost_rr(m, key, ifindex, &answer); | |
368 | if (r < 0) | |
369 | return log_error_errno(r, "Failed to synthesize localhost RRs: %m"); | |
370 | ||
371 | } else if (manager_is_own_hostname(m, name)) { | |
372 | ||
373 | r = synthesize_system_hostname_rr(m, key, ifindex, &answer); | |
374 | if (r < 0) | |
375 | return log_error_errno(r, "Failed to synthesize system hostname RRs: %m"); | |
376 | ||
377 | } else if (is_gateway_hostname(name)) { | |
378 | ||
379 | r = synthesize_gateway_rr(m, key, ifindex, &answer); | |
380 | if (r < 0) | |
381 | return log_error_errno(r, "Failed to synthesize gateway RRs: %m"); | |
382 | ||
383 | } else if ((dns_name_endswith(name, "127.in-addr.arpa") > 0 && dns_name_equal(name, "2.0.0.127.in-addr.arpa") == 0) || | |
384 | dns_name_equal(name, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0) { | |
385 | ||
386 | r = synthesize_localhost_ptr(m, key, ifindex, &answer); | |
387 | if (r < 0) | |
388 | return log_error_errno(r, "Failed to synthesize localhost PTR RRs: %m"); | |
389 | ||
390 | } else if (dns_name_address(name, &af, &address) > 0) { | |
391 | ||
392 | r = synthesize_system_hostname_ptr(m, af, &address, ifindex, &answer); | |
393 | if (r < 0) | |
394 | return log_error_errno(r, "Failed to synthesize system hostname PTR RR: %m"); | |
395 | ||
396 | r = synthesize_gateway_ptr(m, af, &address, ifindex, &answer); | |
397 | if (r < 0) | |
398 | return log_error_errno(r, "Failed to synthesize gateway hostname PTR RR: %m"); | |
528e685e LP |
399 | } else |
400 | continue; | |
401 | ||
402 | found = true; | |
839a4a20 LP |
403 | } |
404 | ||
528e685e | 405 | r = found; |
839a4a20 LP |
406 | |
407 | if (ret) { | |
408 | *ret = answer; | |
409 | answer = NULL; | |
410 | } | |
411 | ||
839a4a20 LP |
412 | return r; |
413 | } |