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b30bf55d 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 "resolved-dns-stub.h" | |
22 | #include "socket-util.h" | |
23 | ||
24 | /* The MTU of the loopback device is 64K on Linux, advertise that as maximum datagram size, but subtract the Ethernet, | |
25 | * IP and UDP header sizes */ | |
26 | #define ADVERTISE_DATAGRAM_SIZE_MAX (65536U-14U-20U-8U) | |
27 | ||
424e490b ZJS |
28 | static int manager_dns_stub_udp_fd(Manager *m); |
29 | static int manager_dns_stub_tcp_fd(Manager *m); | |
30 | ||
b30bf55d | 31 | static int dns_stub_make_reply_packet( |
e8d23f92 | 32 | DnsPacket **p, |
51027656 | 33 | size_t max_size, |
b30bf55d | 34 | DnsQuestion *q, |
51027656 LP |
35 | DnsAnswer *answer, |
36 | bool *ret_truncated) { | |
b30bf55d | 37 | |
51027656 | 38 | bool truncated = false; |
b30bf55d LP |
39 | DnsResourceRecord *rr; |
40 | unsigned c = 0; | |
41 | int r; | |
42 | ||
e8d23f92 LP |
43 | assert(p); |
44 | ||
b30bf55d LP |
45 | /* Note that we don't bother with any additional RRs, as this is stub is for local lookups only, and hence |
46 | * roundtrips aren't expensive. */ | |
47 | ||
e8d23f92 | 48 | if (!*p) { |
51027656 | 49 | r = dns_packet_new(p, DNS_PROTOCOL_DNS, 0, max_size); |
e8d23f92 LP |
50 | if (r < 0) |
51 | return r; | |
b30bf55d | 52 | |
e8d23f92 LP |
53 | r = dns_packet_append_question(*p, q); |
54 | if (r < 0) | |
55 | return r; | |
b30bf55d | 56 | |
e8d23f92 LP |
57 | DNS_PACKET_HEADER(*p)->qdcount = htobe16(dns_question_size(q)); |
58 | } | |
b30bf55d LP |
59 | |
60 | DNS_ANSWER_FOREACH(rr, answer) { | |
e8d23f92 | 61 | |
b30bf55d LP |
62 | r = dns_question_matches_rr(q, rr, NULL); |
63 | if (r < 0) | |
64 | return r; | |
65 | if (r > 0) | |
66 | goto add; | |
67 | ||
68 | r = dns_question_matches_cname_or_dname(q, rr, NULL); | |
69 | if (r < 0) | |
70 | return r; | |
71 | if (r > 0) | |
72 | goto add; | |
73 | ||
74 | continue; | |
75 | add: | |
01c901e2 | 76 | r = dns_packet_append_rr(*p, rr, 0, NULL, NULL); |
51027656 LP |
77 | if (r == -EMSGSIZE) { |
78 | truncated = true; | |
79 | break; | |
80 | } | |
b30bf55d LP |
81 | if (r < 0) |
82 | return r; | |
83 | ||
84 | c++; | |
85 | } | |
e8d23f92 | 86 | |
51027656 LP |
87 | if (ret_truncated) |
88 | *ret_truncated = truncated; | |
89 | else if (truncated) | |
90 | return -EMSGSIZE; | |
91 | ||
e8d23f92 LP |
92 | DNS_PACKET_HEADER(*p)->ancount = htobe16(be16toh(DNS_PACKET_HEADER(*p)->ancount) + c); |
93 | ||
94 | return 0; | |
95 | } | |
96 | ||
97 | static int dns_stub_finish_reply_packet( | |
98 | DnsPacket *p, | |
99 | uint16_t id, | |
100 | int rcode, | |
51027656 | 101 | bool tc, /* set the Truncated bit? */ |
e8d23f92 LP |
102 | bool add_opt, /* add an OPT RR to this packet? */ |
103 | bool edns0_do, /* set the EDNS0 DNSSEC OK bit? */ | |
104 | bool ad) { /* set the DNSSEC authenticated data bit? */ | |
105 | ||
106 | int r; | |
107 | ||
108 | assert(p); | |
109 | ||
941dd294 LP |
110 | if (!add_opt) { |
111 | /* If the client can't to EDNS0, don't do DO either */ | |
112 | edns0_do = false; | |
113 | ||
114 | /* If the client didn't do EDNS, clamp the rcode to 4 bit */ | |
115 | if (rcode > 0xF) | |
116 | rcode = DNS_RCODE_SERVFAIL; | |
117 | } | |
118 | ||
119 | /* Don't set the AD bit unless DO is on, too */ | |
120 | if (!edns0_do) | |
121 | ad = false; | |
e8d23f92 LP |
122 | |
123 | DNS_PACKET_HEADER(p)->id = id; | |
124 | ||
125 | DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( | |
51027656 LP |
126 | 1 /* qr */, |
127 | 0 /* opcode */, | |
128 | 0 /* aa */, | |
129 | tc /* tc */, | |
130 | 1 /* rd */, | |
131 | 1 /* ra */, | |
e8d23f92 | 132 | ad /* ad */, |
51027656 | 133 | 0 /* cd */, |
e8d23f92 | 134 | rcode)); |
b30bf55d LP |
135 | |
136 | if (add_opt) { | |
137 | r = dns_packet_append_opt(p, ADVERTISE_DATAGRAM_SIZE_MAX, edns0_do, rcode, NULL); | |
138 | if (r < 0) | |
139 | return r; | |
140 | } | |
141 | ||
b30bf55d LP |
142 | return 0; |
143 | } | |
144 | ||
145 | static void dns_stub_detach_stream(DnsStream *s) { | |
146 | assert(s); | |
147 | ||
148 | s->complete = NULL; | |
149 | s->on_packet = NULL; | |
150 | s->query = NULL; | |
151 | } | |
152 | ||
153 | static int dns_stub_send(Manager *m, DnsStream *s, DnsPacket *p, DnsPacket *reply) { | |
154 | int r; | |
155 | ||
156 | assert(m); | |
157 | assert(p); | |
158 | assert(reply); | |
159 | ||
160 | if (s) | |
161 | r = dns_stream_write_packet(s, reply); | |
162 | else { | |
163 | int fd; | |
164 | ||
b30bf55d LP |
165 | fd = manager_dns_stub_udp_fd(m); |
166 | if (fd < 0) | |
167 | return log_debug_errno(fd, "Failed to get reply socket: %m"); | |
168 | ||
169 | /* Note that it is essential here that we explicitly choose the source IP address for this packet. This | |
170 | * is because otherwise the kernel will choose it automatically based on the routing table and will | |
171 | * thus pick 127.0.0.1 rather than 127.0.0.53. */ | |
172 | ||
173 | r = manager_send(m, fd, LOOPBACK_IFINDEX, p->family, &p->sender, p->sender_port, &p->destination, reply); | |
174 | } | |
175 | if (r < 0) | |
176 | return log_debug_errno(r, "Failed to send reply packet: %m"); | |
177 | ||
178 | return 0; | |
179 | } | |
180 | ||
2b2d98c1 | 181 | static int dns_stub_send_failure(Manager *m, DnsStream *s, DnsPacket *p, int rcode, bool authenticated) { |
b30bf55d LP |
182 | _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; |
183 | int r; | |
184 | ||
185 | assert(m); | |
186 | assert(p); | |
187 | ||
51027656 | 188 | r = dns_stub_make_reply_packet(&reply, DNS_PACKET_PAYLOAD_SIZE_MAX(p), p->question, NULL, NULL); |
e8d23f92 LP |
189 | if (r < 0) |
190 | return log_debug_errno(r, "Failed to make failure packet: %m"); | |
191 | ||
51027656 | 192 | r = dns_stub_finish_reply_packet(reply, DNS_PACKET_ID(p), rcode, false, !!p->opt, DNS_PACKET_DO(p), authenticated); |
b30bf55d LP |
193 | if (r < 0) |
194 | return log_debug_errno(r, "Failed to build failure packet: %m"); | |
195 | ||
196 | return dns_stub_send(m, s, p, reply); | |
197 | } | |
198 | ||
199 | static void dns_stub_query_complete(DnsQuery *q) { | |
200 | int r; | |
201 | ||
202 | assert(q); | |
203 | assert(q->request_dns_packet); | |
204 | ||
205 | switch (q->state) { | |
206 | ||
51027656 LP |
207 | case DNS_TRANSACTION_SUCCESS: { |
208 | bool truncated; | |
e8d23f92 | 209 | |
51027656 | 210 | r = dns_stub_make_reply_packet(&q->reply_dns_packet, DNS_PACKET_PAYLOAD_SIZE_MAX(q->request_dns_packet), q->question_idna, q->answer, &truncated); |
e8d23f92 LP |
211 | if (r < 0) { |
212 | log_debug_errno(r, "Failed to build reply packet: %m"); | |
213 | break; | |
214 | } | |
b30bf55d | 215 | |
e8d23f92 LP |
216 | r = dns_query_process_cname(q); |
217 | if (r == -ELOOP) { | |
2b2d98c1 | 218 | (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL, false); |
e8d23f92 LP |
219 | break; |
220 | } | |
221 | if (r < 0) { | |
222 | log_debug_errno(r, "Failed to process CNAME: %m"); | |
223 | break; | |
224 | } | |
225 | if (r == DNS_QUERY_RESTARTED) | |
226 | return; | |
227 | ||
228 | r = dns_stub_finish_reply_packet( | |
229 | q->reply_dns_packet, | |
b30bf55d LP |
230 | DNS_PACKET_ID(q->request_dns_packet), |
231 | q->answer_rcode, | |
51027656 | 232 | truncated, |
b30bf55d LP |
233 | !!q->request_dns_packet->opt, |
234 | DNS_PACKET_DO(q->request_dns_packet), | |
941dd294 | 235 | dns_query_fully_authenticated(q)); |
b30bf55d | 236 | if (r < 0) { |
e8d23f92 | 237 | log_debug_errno(r, "Failed to finish reply packet: %m"); |
b30bf55d LP |
238 | break; |
239 | } | |
240 | ||
e8d23f92 | 241 | (void) dns_stub_send(q->manager, q->request_dns_stream, q->request_dns_packet, q->reply_dns_packet); |
b30bf55d | 242 | break; |
51027656 | 243 | } |
b30bf55d LP |
244 | |
245 | case DNS_TRANSACTION_RCODE_FAILURE: | |
2b2d98c1 | 246 | (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, q->answer_rcode, dns_query_fully_authenticated(q)); |
b30bf55d LP |
247 | break; |
248 | ||
249 | case DNS_TRANSACTION_NOT_FOUND: | |
2b2d98c1 | 250 | (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_NXDOMAIN, dns_query_fully_authenticated(q)); |
b30bf55d LP |
251 | break; |
252 | ||
253 | case DNS_TRANSACTION_TIMEOUT: | |
254 | case DNS_TRANSACTION_ATTEMPTS_MAX_REACHED: | |
255 | /* Propagate a timeout as a no packet, i.e. that the client also gets a timeout */ | |
256 | break; | |
257 | ||
258 | case DNS_TRANSACTION_NO_SERVERS: | |
259 | case DNS_TRANSACTION_INVALID_REPLY: | |
260 | case DNS_TRANSACTION_ERRNO: | |
261 | case DNS_TRANSACTION_ABORTED: | |
262 | case DNS_TRANSACTION_DNSSEC_FAILED: | |
263 | case DNS_TRANSACTION_NO_TRUST_ANCHOR: | |
264 | case DNS_TRANSACTION_RR_TYPE_UNSUPPORTED: | |
265 | case DNS_TRANSACTION_NETWORK_DOWN: | |
2b2d98c1 | 266 | (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL, false); |
b30bf55d LP |
267 | break; |
268 | ||
269 | case DNS_TRANSACTION_NULL: | |
270 | case DNS_TRANSACTION_PENDING: | |
271 | case DNS_TRANSACTION_VALIDATING: | |
272 | default: | |
273 | assert_not_reached("Impossible state"); | |
274 | } | |
275 | ||
276 | /* If there's a packet to write set, let's leave the stream around */ | |
277 | if (q->request_dns_stream && DNS_STREAM_QUEUED(q->request_dns_stream)) { | |
278 | ||
279 | /* Detach the stream from our query (make it an orphan), but do not drop the reference to it. The | |
280 | * default completion action of the stream will drop the reference. */ | |
281 | ||
282 | dns_stub_detach_stream(q->request_dns_stream); | |
283 | q->request_dns_stream = NULL; | |
284 | } | |
285 | ||
286 | dns_query_free(q); | |
287 | } | |
288 | ||
289 | static int dns_stub_stream_complete(DnsStream *s, int error) { | |
290 | assert(s); | |
291 | ||
292 | log_debug_errno(error, "DNS TCP connection terminated, destroying query: %m"); | |
293 | ||
294 | assert(s->query); | |
295 | dns_query_free(s->query); | |
296 | ||
297 | return 0; | |
298 | } | |
299 | ||
300 | static void dns_stub_process_query(Manager *m, DnsStream *s, DnsPacket *p) { | |
301 | DnsQuery *q = NULL; | |
302 | int r; | |
303 | ||
304 | assert(m); | |
305 | assert(p); | |
306 | assert(p->protocol == DNS_PROTOCOL_DNS); | |
307 | ||
308 | /* Takes ownership of the *s stream object */ | |
309 | ||
310 | if (in_addr_is_localhost(p->family, &p->sender) <= 0 || | |
311 | in_addr_is_localhost(p->family, &p->destination) <= 0) { | |
312 | log_error("Got packet on unexpected IP range, refusing."); | |
2b2d98c1 | 313 | dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL, false); |
b30bf55d LP |
314 | goto fail; |
315 | } | |
316 | ||
317 | r = dns_packet_extract(p); | |
318 | if (r < 0) { | |
319 | log_debug_errno(r, "Failed to extract resources from incoming packet, ignoring packet: %m"); | |
2b2d98c1 | 320 | dns_stub_send_failure(m, s, p, DNS_RCODE_FORMERR, false); |
b30bf55d LP |
321 | goto fail; |
322 | } | |
323 | ||
324 | if (!DNS_PACKET_VERSION_SUPPORTED(p)) { | |
325 | log_debug("Got EDNS OPT field with unsupported version number."); | |
2b2d98c1 | 326 | dns_stub_send_failure(m, s, p, DNS_RCODE_BADVERS, false); |
b30bf55d LP |
327 | goto fail; |
328 | } | |
329 | ||
330 | if (dns_type_is_obsolete(p->question->keys[0]->type)) { | |
331 | log_debug("Got message with obsolete key type, refusing."); | |
2b2d98c1 | 332 | dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP, false); |
b30bf55d LP |
333 | goto fail; |
334 | } | |
335 | ||
336 | if (dns_type_is_zone_transer(p->question->keys[0]->type)) { | |
337 | log_debug("Got request for zone transfer, refusing."); | |
2b2d98c1 | 338 | dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP, false); |
b30bf55d LP |
339 | goto fail; |
340 | } | |
341 | ||
342 | if (!DNS_PACKET_RD(p)) { | |
343 | /* If the "rd" bit is off (i.e. recursion was not requested), then refuse operation */ | |
344 | log_debug("Got request with recursion disabled, refusing."); | |
2b2d98c1 | 345 | dns_stub_send_failure(m, s, p, DNS_RCODE_REFUSED, false); |
b30bf55d LP |
346 | goto fail; |
347 | } | |
348 | ||
349 | if (DNS_PACKET_DO(p) && DNS_PACKET_CD(p)) { | |
350 | log_debug("Got request with DNSSEC CD bit set, refusing."); | |
2b2d98c1 | 351 | dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP, false); |
b30bf55d LP |
352 | goto fail; |
353 | } | |
354 | ||
e8d23f92 | 355 | r = dns_query_new(m, &q, p->question, p->question, 0, SD_RESOLVED_PROTOCOLS_ALL|SD_RESOLVED_NO_SEARCH); |
b30bf55d LP |
356 | if (r < 0) { |
357 | log_error_errno(r, "Failed to generate query object: %m"); | |
2b2d98c1 | 358 | dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL, false); |
b30bf55d LP |
359 | goto fail; |
360 | } | |
361 | ||
362 | /* Request that the TTL is corrected by the cached time for this lookup, so that we return vaguely useful TTLs */ | |
363 | q->clamp_ttl = true; | |
364 | ||
365 | q->request_dns_packet = dns_packet_ref(p); | |
366 | q->request_dns_stream = dns_stream_ref(s); /* make sure the stream stays around until we can send a reply through it */ | |
367 | q->complete = dns_stub_query_complete; | |
368 | ||
369 | if (s) { | |
370 | s->on_packet = NULL; | |
371 | s->complete = dns_stub_stream_complete; | |
372 | s->query = q; | |
373 | } | |
374 | ||
375 | r = dns_query_go(q); | |
376 | if (r < 0) { | |
377 | log_error_errno(r, "Failed to start query: %m"); | |
2b2d98c1 | 378 | dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL, false); |
b30bf55d LP |
379 | goto fail; |
380 | } | |
381 | ||
52e63427 | 382 | log_debug("Processing query..."); |
b30bf55d LP |
383 | return; |
384 | ||
385 | fail: | |
386 | if (s && DNS_STREAM_QUEUED(s)) | |
387 | dns_stub_detach_stream(s); | |
388 | ||
389 | dns_query_free(q); | |
390 | } | |
391 | ||
392 | static int on_dns_stub_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
393 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
394 | Manager *m = userdata; | |
395 | int r; | |
396 | ||
397 | r = manager_recv(m, fd, DNS_PROTOCOL_DNS, &p); | |
398 | if (r <= 0) | |
399 | return r; | |
400 | ||
401 | if (dns_packet_validate_query(p) > 0) { | |
402 | log_debug("Got DNS stub UDP query packet for id %u", DNS_PACKET_ID(p)); | |
403 | ||
404 | dns_stub_process_query(m, NULL, p); | |
405 | } else | |
406 | log_debug("Invalid DNS stub UDP packet, ignoring."); | |
407 | ||
408 | return 0; | |
409 | } | |
410 | ||
424e490b | 411 | static int manager_dns_stub_udp_fd(Manager *m) { |
b30bf55d | 412 | static const int one = 1; |
b30bf55d LP |
413 | union sockaddr_union sa = { |
414 | .in.sin_family = AF_INET, | |
415 | .in.sin_port = htobe16(53), | |
416 | .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB), | |
417 | }; | |
424e490b | 418 | _cleanup_close_ int fd = -1; |
b30bf55d LP |
419 | int r; |
420 | ||
421 | if (m->dns_stub_udp_fd >= 0) | |
422 | return m->dns_stub_udp_fd; | |
423 | ||
424e490b ZJS |
424 | fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
425 | if (fd < 0) | |
b30bf55d LP |
426 | return -errno; |
427 | ||
424e490b ZJS |
428 | if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0) |
429 | return -errno; | |
b30bf55d | 430 | |
424e490b ZJS |
431 | if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0) |
432 | return -errno; | |
b30bf55d | 433 | |
424e490b ZJS |
434 | if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0) |
435 | return -errno; | |
b30bf55d LP |
436 | |
437 | /* Make sure no traffic from outside the local host can leak to onto this socket */ | |
424e490b ZJS |
438 | if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0) |
439 | return -errno; | |
b30bf55d | 440 | |
424e490b ZJS |
441 | if (bind(fd, &sa.sa, sizeof(sa.in)) < 0) |
442 | return -errno; | |
b30bf55d | 443 | |
424e490b | 444 | r = sd_event_add_io(m->event, &m->dns_stub_udp_event_source, fd, EPOLLIN, on_dns_stub_packet, m); |
b30bf55d | 445 | if (r < 0) |
424e490b | 446 | return r; |
b30bf55d LP |
447 | |
448 | (void) sd_event_source_set_description(m->dns_stub_udp_event_source, "dns-stub-udp"); | |
424e490b ZJS |
449 | m->dns_stub_udp_fd = fd; |
450 | fd = -1; | |
b30bf55d LP |
451 | |
452 | return m->dns_stub_udp_fd; | |
b30bf55d LP |
453 | } |
454 | ||
455 | static int on_dns_stub_stream_packet(DnsStream *s) { | |
456 | assert(s); | |
457 | assert(s->read_packet); | |
458 | ||
459 | if (dns_packet_validate_query(s->read_packet) > 0) { | |
460 | log_debug("Got DNS stub TCP query packet for id %u", DNS_PACKET_ID(s->read_packet)); | |
461 | ||
462 | dns_stub_process_query(s->manager, s, s->read_packet); | |
463 | } else | |
464 | log_debug("Invalid DNS stub TCP packet, ignoring."); | |
465 | ||
466 | /* Drop the reference to the stream. Either a query was created and added its own reference to the stream now, | |
467 | * or that didn't happen in which case we want to free the stream */ | |
468 | dns_stream_unref(s); | |
469 | ||
470 | return 0; | |
471 | } | |
472 | ||
473 | static int on_dns_stub_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
474 | DnsStream *stream; | |
475 | Manager *m = userdata; | |
476 | int cfd, r; | |
477 | ||
478 | cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC); | |
479 | if (cfd < 0) { | |
3742095b | 480 | if (IN_SET(errno, EAGAIN, EINTR)) |
b30bf55d LP |
481 | return 0; |
482 | ||
483 | return -errno; | |
484 | } | |
485 | ||
486 | r = dns_stream_new(m, &stream, DNS_PROTOCOL_DNS, cfd); | |
487 | if (r < 0) { | |
488 | safe_close(cfd); | |
489 | return r; | |
490 | } | |
491 | ||
492 | stream->on_packet = on_dns_stub_stream_packet; | |
493 | ||
494 | /* We let the reference to the stream dangling here, it will either be dropped by the default "complete" action | |
495 | * of the stream, or by our packet callback, or when the manager is shut down. */ | |
496 | ||
497 | return 0; | |
498 | } | |
499 | ||
424e490b | 500 | static int manager_dns_stub_tcp_fd(Manager *m) { |
b30bf55d | 501 | static const int one = 1; |
b30bf55d LP |
502 | union sockaddr_union sa = { |
503 | .in.sin_family = AF_INET, | |
504 | .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB), | |
505 | .in.sin_port = htobe16(53), | |
506 | }; | |
424e490b | 507 | _cleanup_close_ int fd = -1; |
b30bf55d LP |
508 | int r; |
509 | ||
510 | if (m->dns_stub_tcp_fd >= 0) | |
511 | return m->dns_stub_tcp_fd; | |
512 | ||
424e490b ZJS |
513 | fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
514 | if (fd < 0) | |
b30bf55d LP |
515 | return -errno; |
516 | ||
424e490b ZJS |
517 | if (setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof one) < 0) |
518 | return -errno; | |
b30bf55d | 519 | |
424e490b ZJS |
520 | if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0) |
521 | return -errno; | |
b30bf55d | 522 | |
424e490b ZJS |
523 | if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0) |
524 | return -errno; | |
b30bf55d | 525 | |
424e490b ZJS |
526 | if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0) |
527 | return -errno; | |
b30bf55d LP |
528 | |
529 | /* Make sure no traffic from outside the local host can leak to onto this socket */ | |
424e490b ZJS |
530 | if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0) |
531 | return -errno; | |
b30bf55d | 532 | |
424e490b ZJS |
533 | if (bind(fd, &sa.sa, sizeof(sa.in)) < 0) |
534 | return -errno; | |
b30bf55d | 535 | |
424e490b ZJS |
536 | if (listen(fd, SOMAXCONN) < 0) |
537 | return -errno; | |
b30bf55d | 538 | |
424e490b | 539 | r = sd_event_add_io(m->event, &m->dns_stub_tcp_event_source, fd, EPOLLIN, on_dns_stub_stream, m); |
b30bf55d | 540 | if (r < 0) |
424e490b | 541 | return r; |
b30bf55d LP |
542 | |
543 | (void) sd_event_source_set_description(m->dns_stub_tcp_event_source, "dns-stub-tcp"); | |
424e490b ZJS |
544 | m->dns_stub_tcp_fd = fd; |
545 | fd = -1; | |
b30bf55d LP |
546 | |
547 | return m->dns_stub_tcp_fd; | |
b30bf55d LP |
548 | } |
549 | ||
550 | int manager_dns_stub_start(Manager *m) { | |
424e490b | 551 | const char *t = "UDP"; |
01b0669e | 552 | int r = 0; |
b30bf55d LP |
553 | |
554 | assert(m); | |
555 | ||
d5da7707 ZJS |
556 | if (m->dns_stub_listener_mode == DNS_STUB_LISTENER_NO) |
557 | log_debug("Not creating stub listener."); | |
558 | else | |
559 | log_debug("Creating stub listener using %s.", | |
560 | m->dns_stub_listener_mode == DNS_STUB_LISTENER_UDP ? "UDP" : | |
561 | m->dns_stub_listener_mode == DNS_STUB_LISTENER_TCP ? "TCP" : | |
562 | "UDP/TCP"); | |
563 | ||
424e490b | 564 | if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP)) |
1ae43295 | 565 | r = manager_dns_stub_udp_fd(m); |
b30bf55d | 566 | |
424e490b ZJS |
567 | if (r >= 0 && |
568 | IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_TCP)) { | |
569 | t = "TCP"; | |
1ae43295 | 570 | r = manager_dns_stub_tcp_fd(m); |
1ae43295 | 571 | } |
b30bf55d | 572 | |
0f4db364 ZJS |
573 | if (IN_SET(r, -EADDRINUSE, -EPERM)) { |
574 | if (r == -EADDRINUSE) | |
575 | log_warning_errno(r, | |
576 | "Another process is already listening on %s socket 127.0.0.53:53.\n" | |
577 | "Turning off local DNS stub support.", t); | |
578 | else | |
579 | log_warning_errno(r, | |
580 | "Failed to listen on %s socket 127.0.0.53:53: %m.\n" | |
581 | "Turning off local DNS stub support.", t); | |
424e490b ZJS |
582 | manager_dns_stub_stop(m); |
583 | } else if (r < 0) | |
584 | return log_error_errno(r, "Failed to listen on %s socket 127.0.0.53:53: %m", t); | |
b30bf55d LP |
585 | |
586 | return 0; | |
587 | } | |
588 | ||
589 | void manager_dns_stub_stop(Manager *m) { | |
590 | assert(m); | |
591 | ||
592 | m->dns_stub_udp_event_source = sd_event_source_unref(m->dns_stub_udp_event_source); | |
593 | m->dns_stub_tcp_event_source = sd_event_source_unref(m->dns_stub_tcp_event_source); | |
594 | ||
595 | m->dns_stub_udp_fd = safe_close(m->dns_stub_udp_fd); | |
596 | m->dns_stub_tcp_fd = safe_close(m->dns_stub_tcp_fd); | |
597 | } |