-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathDnsProxyListener.cpp
1345 lines (1156 loc) · 50.6 KB
/
DnsProxyListener.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "DnsProxyListener.h"
#include <arpa/inet.h>
#include <dirent.h>
#include <errno.h>
#include <linux/if.h>
#include <math.h>
#include <net/if.h>
#include <netdb.h>
#include <netinet/in.h>
#include <resolv.h> // b64_pton()
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#define LOG_TAG "resolv"
#include <algorithm>
#include <vector>
#include <android/multinetwork.h> // ResNsendFlags
#include <cutils/misc.h> // FIRST_APPLICATION_UID
#include <cutils/multiuser.h>
#include <netdutils/InternetAddresses.h>
#include <netdutils/ResponseCode.h>
#include <netdutils/Stopwatch.h>
#include <netdutils/ThreadUtil.h>
#include <private/android_filesystem_config.h> // AID_SYSTEM
#include <statslog_resolv.h>
#include <sysutils/SocketClient.h>
#include "DnsResolver.h"
#include "Experiments.h"
#include "NetdPermissions.h"
#include "OperationLimiter.h"
#include "PrivateDnsConfiguration.h"
#include "ResolverEventReporter.h"
#include "dnsproxyd_protocol/DnsProxydProtocol.h" // NETID_USE_LOCAL_NAMESERVERS
#include "getaddrinfo.h"
#include "gethnamaddr.h"
#include "res_send.h"
#include "resolv_cache.h"
#include "resolv_private.h"
#include "stats.h" // RCODE_TIMEOUT
#include "stats.pb.h"
using aidl::android::net::metrics::INetdEventListener;
using aidl::android::net::resolv::aidl::DnsHealthEventParcel;
using aidl::android::net::resolv::aidl::IDnsResolverUnsolicitedEventListener;
using std::span;
namespace android {
using netdutils::ResponseCode;
using netdutils::Stopwatch;
namespace net {
namespace {
// Limits the number of outstanding DNS queries by client UID.
constexpr int MAX_QUERIES_PER_UID = 256;
android::netdutils::OperationLimiter<uid_t> queryLimiter(MAX_QUERIES_PER_UID);
void logArguments(int argc, char** argv) {
if (!WOULD_LOG(VERBOSE)) return;
for (int i = 0; i < argc; i++) {
LOG(VERBOSE) << __func__ << ": argv[" << i << "]=" << (argv[i] ? argv[i] : "null");
}
}
bool checkAndClearUseLocalNameserversFlag(unsigned* netid) {
if (netid == nullptr || ((*netid) & NETID_USE_LOCAL_NAMESERVERS) == 0) {
return false;
}
*netid = (*netid) & ~NETID_USE_LOCAL_NAMESERVERS;
return true;
}
constexpr bool requestingUseLocalNameservers(unsigned flags) {
return (flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS) != 0;
}
bool queryingViaTls(unsigned dns_netid) {
const auto privateDnsStatus = PrivateDnsConfiguration::getInstance().getStatus(dns_netid);
switch (privateDnsStatus.mode) {
case PrivateDnsMode::OPPORTUNISTIC:
return !privateDnsStatus.validatedServers().empty();
case PrivateDnsMode::STRICT:
return true;
default:
return false;
}
}
bool hasPermissionToBypassPrivateDns(uid_t uid) {
static_assert(AID_SYSTEM >= 0 && AID_SYSTEM < FIRST_APPLICATION_UID,
"Calls from AID_SYSTEM must not result in a permission check to avoid deadlock.");
if (uid >= 0 && uid < FIRST_APPLICATION_UID) {
return true;
}
for (const char* const permission :
{PERM_CONNECTIVITY_USE_RESTRICTED_NETWORKS, PERM_NETWORK_BYPASS_PRIVATE_DNS,
PERM_MAINLINE_NETWORK_STACK}) {
if (gResNetdCallbacks.check_calling_permission(permission)) {
return true;
}
}
return false;
}
void maybeFixupNetContext(android_net_context* ctx, pid_t pid) {
if (requestingUseLocalNameservers(ctx->flags) && !hasPermissionToBypassPrivateDns(ctx->uid)) {
// Not permitted; clear the flag.
ctx->flags &= ~NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
if (!requestingUseLocalNameservers(ctx->flags)) {
// If we're not explicitly bypassing DNS-over-TLS servers, check whether
// DNS-over-TLS is in use as an indicator for when to use more modern
// DNS resolution mechanics.
if (queryingViaTls(ctx->dns_netid)) {
ctx->flags |= NET_CONTEXT_FLAG_USE_DNS_OVER_TLS | NET_CONTEXT_FLAG_USE_EDNS;
}
}
ctx->pid = pid;
}
void addIpAddrWithinLimit(std::vector<std::string>* ip_addrs, const sockaddr* addr,
socklen_t addrlen);
int extractResNsendAnswers(std::span<const uint8_t> answer, int ipType,
std::vector<std::string>* ip_addrs) {
int total_ip_addr_count = 0;
ns_msg handle;
if (ns_initparse(answer.data(), answer.size(), &handle) < 0) {
return 0;
}
int ancount = ns_msg_count(handle, ns_s_an);
ns_rr rr;
for (int i = 0; i < ancount; i++) {
if (ns_parserr(&handle, ns_s_an, i, &rr) < 0) {
continue;
}
const uint8_t* rdata = ns_rr_rdata(rr);
if (ipType == ns_t_a) {
sockaddr_in sin = {.sin_family = AF_INET};
memcpy(&sin.sin_addr, rdata, sizeof(sin.sin_addr));
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin, sizeof(sin));
total_ip_addr_count++;
} else if (ipType == ns_t_aaaa) {
sockaddr_in6 sin6 = {.sin6_family = AF_INET6};
memcpy(&sin6.sin6_addr, rdata, sizeof(sin6.sin6_addr));
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin6, sizeof(sin6));
total_ip_addr_count++;
}
}
return total_ip_addr_count;
}
int extractGetAddrInfoAnswers(const addrinfo* result, std::vector<std::string>* ip_addrs) {
int total_ip_addr_count = 0;
if (result == nullptr) {
return 0;
}
for (const addrinfo* ai = result; ai; ai = ai->ai_next) {
sockaddr* ai_addr = ai->ai_addr;
if (ai_addr) {
addIpAddrWithinLimit(ip_addrs, ai_addr, ai->ai_addrlen);
total_ip_addr_count++;
}
}
return total_ip_addr_count;
}
int extractGetHostByNameAnswers(const hostent* hp, std::vector<std::string>* ip_addrs) {
int total_ip_addr_count = 0;
if (hp == nullptr) {
return 0;
}
if (hp->h_addrtype == AF_INET) {
in_addr** list = (in_addr**)hp->h_addr_list;
for (int i = 0; list[i] != nullptr; i++) {
sockaddr_in sin = {.sin_family = AF_INET, .sin_addr = *list[i]};
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin, sizeof(sin));
total_ip_addr_count++;
}
} else if (hp->h_addrtype == AF_INET6) {
in6_addr** list = (in6_addr**)hp->h_addr_list;
for (int i = 0; list[i] != nullptr; i++) {
sockaddr_in6 sin6 = {.sin6_family = AF_INET6, .sin6_addr = *list[i]};
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin6, sizeof(sin6));
total_ip_addr_count++;
}
}
return total_ip_addr_count;
}
int rcodeToAiError(int rcode) {
switch (rcode) {
case NOERROR:
return 0;
case RCODE_TIMEOUT:
return NETD_RESOLV_TIMEOUT;
default:
return EAI_NODATA;
}
}
int resNSendToAiError(int err, int rcode) {
if (err > 0) {
return rcodeToAiError(rcode);
}
if (err == -ETIMEDOUT) {
return NETD_RESOLV_TIMEOUT;
}
return EAI_SYSTEM;
}
template <typename IntegralType>
bool simpleStrtoul(const char* input, IntegralType* output, int base = 10) {
char* endPtr;
errno = 0;
auto result = strtoul(input, &endPtr, base);
// Check the length in order to ensure there is no "-" sign
if (!*input || *endPtr || (endPtr - input) != static_cast<ptrdiff_t>(strlen(input)) ||
(errno == ERANGE && (result == ULONG_MAX))) {
return false;
}
*output = result;
return true;
}
bool setQueryId(span<uint8_t> msg, uint16_t query_id) {
if ((size_t)msg.size() < sizeof(HEADER)) {
errno = EINVAL;
return false;
}
auto hp = reinterpret_cast<HEADER*>(msg.data());
hp->id = htons(query_id);
return true;
}
bool parseQuery(span<const uint8_t> msg, uint16_t* query_id, int* rr_type, std::string* rr_name) {
ns_msg handle;
ns_rr rr;
if (ns_initparse(msg.data(), msg.size(), &handle) < 0 ||
ns_parserr(&handle, ns_s_qd, 0, &rr) < 0) {
return false;
}
*query_id = ns_msg_id(handle);
*rr_name = ns_rr_name(rr);
*rr_type = ns_rr_type(rr);
return true;
}
// Note: Even if it returns PDM_OFF, it doesn't mean there's no DoT stats in the message
// because Private DNS mode can change at any time.
PrivateDnsModes getPrivateDnsModeForMetrics(uint32_t netId) {
switch (PrivateDnsConfiguration::getInstance().getStatus(netId).mode) {
case PrivateDnsMode::OFF:
// It can also be due to netId not found.
return PrivateDnsModes::PDM_OFF;
case PrivateDnsMode::OPPORTUNISTIC:
return PrivateDnsModes::PDM_OPPORTUNISTIC;
case PrivateDnsMode::STRICT:
return PrivateDnsModes::PDM_STRICT;
default:
return PrivateDnsModes::PDM_UNKNOWN;
}
}
void initDnsEvent(NetworkDnsEventReported* event, const android_net_context& netContext) {
// The value 0 has the special meaning of unset/unknown in Statsd atoms. So, we set both
// flags to -1 as default value.
// 1. The hints flag is only used in resolv_getaddrinfo. When user set it to -1 in
// resolv_getaddrinfo, the flag will cause validation (validateHints) failure in
// getaddrinfo, so it will not do DNS query and will upload DNS stats log with
// return_code = RC_EAI_BADFLAGS.
// 2. The res_nsend flags are only used in resolv_res_nsend. When user set it to -1 in
// resolv_res_nsend,res_nsend will do nothing special by the setting.
event->set_hints_ai_flags(-1);
event->set_res_nsend_flags(-1);
event->set_private_dns_modes(getPrivateDnsModeForMetrics(netContext.dns_netid));
}
// Return 0 if the event should not be logged.
// Otherwise, return subsampling_denom
uint32_t getDnsEventSubsamplingRate(int netid, int returnCode, bool isMdns) {
uint32_t subsampling_denom = resolv_cache_get_subsampling_denom(netid, returnCode, isMdns);
if (subsampling_denom == 0) return 0;
// Sample the event with a chance of 1 / denom.
return (arc4random_uniform(subsampling_denom) == 0) ? subsampling_denom : 0;
}
void maybeLogQuery(int eventType, const android_net_context& netContext,
const NetworkDnsEventReported& event, const std::string& query_name,
const std::vector<std::string>& ip_addrs) {
// Skip reverse queries.
if (eventType == INetdEventListener::EVENT_GETHOSTBYADDR) return;
for (const auto& query : event.dns_query_events().dns_query_event()) {
// Log it when the cache misses.
if (query.cache_hit() != CS_FOUND) {
const int timeTakenMs = event.latency_micros() / 1000;
DnsQueryLog::Record record(netContext.dns_netid, netContext.uid, netContext.pid,
query_name, ip_addrs, timeTakenMs);
gDnsResolv->dnsQueryLog().push(std::move(record));
return;
}
}
}
void reportDnsEvent(int eventType, const android_net_context& netContext, int latencyUs,
int returnCode, NetworkDnsEventReported& event, const std::string& query_name,
const std::vector<std::string>& ip_addrs = {}, int total_ip_addr_count = 0) {
uint32_t rate =
(query_name.ends_with(".local") && is_mdns_supported_network(netContext.dns_netid) &&
android::net::Experiments::getInstance()->getFlag("mdns_resolution", 1))
? getDnsEventSubsamplingRate(netContext.dns_netid, returnCode, true)
: getDnsEventSubsamplingRate(netContext.dns_netid, returnCode, false);
if (rate) {
const std::string& dnsQueryStats = event.dns_query_events().SerializeAsString();
stats::BytesField dnsQueryBytesField{dnsQueryStats.c_str(), dnsQueryStats.size()};
event.set_return_code(static_cast<ReturnCode>(returnCode));
event.set_network_type(resolv_get_network_types_for_net(netContext.dns_netid));
android::net::stats::stats_write(android::net::stats::NETWORK_DNS_EVENT_REPORTED,
event.event_type(), event.return_code(),
event.latency_micros(), event.hints_ai_flags(),
event.res_nsend_flags(), event.network_type(),
event.private_dns_modes(), dnsQueryBytesField, rate);
}
maybeLogQuery(eventType, netContext, event, query_name, ip_addrs);
const auto& listeners = ResolverEventReporter::getInstance().getListeners();
if (listeners.empty()) {
LOG(ERROR) << __func__
<< ": DNS event not sent since no INetdEventListener receiver is available.";
}
const int latencyMs = latencyUs / 1000;
for (const auto& it : listeners) {
it->onDnsEvent(netContext.dns_netid, eventType, returnCode, latencyMs, query_name, ip_addrs,
total_ip_addr_count, netContext.uid);
}
const auto& unsolEventListeners = ResolverEventReporter::getInstance().getUnsolEventListeners();
if (returnCode == NETD_RESOLV_TIMEOUT) {
const DnsHealthEventParcel dnsHealthEvent = {
.netId = static_cast<int32_t>(netContext.dns_netid),
.healthResult = IDnsResolverUnsolicitedEventListener::DNS_HEALTH_RESULT_TIMEOUT,
};
for (const auto& it : unsolEventListeners) {
it->onDnsHealthEvent(dnsHealthEvent);
}
} else if (returnCode == NOERROR) {
DnsHealthEventParcel dnsHealthEvent = {
.netId = static_cast<int32_t>(netContext.dns_netid),
.healthResult = IDnsResolverUnsolicitedEventListener::DNS_HEALTH_RESULT_OK,
};
for (const auto& query : event.dns_query_events().dns_query_event()) {
if (query.cache_hit() != CS_FOUND && query.rcode() == NS_R_NO_ERROR) {
dnsHealthEvent.successRttMicros.push_back(query.latency_micros());
}
}
if (!dnsHealthEvent.successRttMicros.empty()) {
for (const auto& it : unsolEventListeners) {
it->onDnsHealthEvent(dnsHealthEvent);
}
}
}
}
bool onlyIPv4Answers(const addrinfo* res) {
// Null addrinfo pointer isn't checked because the caller doesn't pass null pointer.
for (const addrinfo* ai = res; ai; ai = ai->ai_next)
if (ai->ai_family != AF_INET) return false;
return true;
}
bool isSpecialUseIPv4Address(const struct in_addr& ia) {
const uint32_t addr = ntohl(ia.s_addr);
// Only check necessary IP ranges in RFC 5735 section 4
return ((addr & 0xff000000) == 0x00000000) || // "This" Network
((addr & 0xff000000) == 0x7f000000) || // Loopback
((addr & 0xffff0000) == 0xa9fe0000) || // Link Local
((addr & 0xf0000000) == 0xe0000000) || // Multicast
(addr == INADDR_BROADCAST); // Limited Broadcast
}
bool isSpecialUseIPv4Address(const struct sockaddr* sa) {
if (sa->sa_family != AF_INET) return false;
return isSpecialUseIPv4Address(((struct sockaddr_in*)sa)->sin_addr);
}
bool onlyNonSpecialUseIPv4Addresses(struct hostent* hp) {
// Null hostent pointer isn't checked because the caller doesn't pass null pointer.
if (hp->h_addrtype != AF_INET) return false;
for (int i = 0; hp->h_addr_list[i] != nullptr; i++)
if (isSpecialUseIPv4Address(*(struct in_addr*)hp->h_addr_list[i])) return false;
return true;
}
bool onlyNonSpecialUseIPv4Addresses(const addrinfo* res) {
// Null addrinfo pointer isn't checked because the caller doesn't pass null pointer.
for (const addrinfo* ai = res; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET) return false;
if (isSpecialUseIPv4Address(ai->ai_addr)) return false;
}
return true;
}
void logDnsQueryResult(const struct hostent* hp) {
if (!WOULD_LOG(DEBUG)) return;
if (hp == nullptr) return;
LOG(DEBUG) << __func__ << ": DNS records:";
for (int i = 0; hp->h_addr_list[i] != nullptr; i++) {
char ip_addr[INET6_ADDRSTRLEN];
if (inet_ntop(hp->h_addrtype, hp->h_addr_list[i], ip_addr, sizeof(ip_addr)) != nullptr) {
LOG(DEBUG) << __func__ << ": [" << i << "] " << hp->h_addrtype;
} else {
PLOG(DEBUG) << __func__ << ": [" << i << "] numeric hostname translation fail";
}
}
}
void logDnsQueryResult(const addrinfo* res) {
if (!WOULD_LOG(DEBUG)) return;
if (res == nullptr) return;
int i;
const addrinfo* ai;
LOG(DEBUG) << __func__ << ": DNS records:";
for (ai = res, i = 0; ai; ai = ai->ai_next, i++) {
if ((ai->ai_family != AF_INET) && (ai->ai_family != AF_INET6)) continue;
char ip_addr[INET6_ADDRSTRLEN];
int ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, ip_addr, sizeof(ip_addr), nullptr, 0,
NI_NUMERICHOST);
if (!ret) {
LOG(DEBUG) << __func__ << ": [" << i << "] " << ai->ai_flags << " " << ai->ai_family
<< " " << ai->ai_socktype << " " << ai->ai_protocol;
} else {
LOG(DEBUG) << __func__ << ": [" << i << "] numeric hostname translation fail " << ret;
}
}
}
bool isValidNat64Prefix(const netdutils::IPPrefix prefix) {
if (prefix.family() != AF_INET6) {
LOG(ERROR) << __func__ << ": Only IPv6 NAT64 prefixes are supported " << prefix.family();
return false;
}
if (prefix.length() != 96) {
LOG(ERROR) << __func__ << ": Only /96 NAT64 prefixes are supported " << prefix.length();
return false;
}
return true;
}
bool synthesizeNat64PrefixWithARecord(const netdutils::IPPrefix& prefix, struct hostent* hp) {
if (hp == nullptr) return false;
if (!onlyNonSpecialUseIPv4Addresses(hp)) return false;
if (!isValidNat64Prefix(prefix)) return false;
struct sockaddr_storage ss = netdutils::IPSockAddr(prefix.ip());
struct sockaddr_in6* v6prefix = (struct sockaddr_in6*)&ss;
for (int i = 0; hp->h_addr_list[i] != nullptr; i++) {
struct in_addr iaOriginal = *(struct in_addr*)hp->h_addr_list[i];
struct in6_addr* ia6 = (struct in6_addr*)hp->h_addr_list[i];
memset(ia6, 0, sizeof(struct in6_addr));
// Synthesize /96 NAT64 prefix in place. The space has reserved by getanswer() and
// _hf_gethtbyname2() in system/netd/resolv/gethnamaddr.cpp and
// system/netd/resolv/sethostent.cpp.
*ia6 = v6prefix->sin6_addr;
ia6->s6_addr32[3] = iaOriginal.s_addr;
if (WOULD_LOG(VERBOSE)) {
char buf[INET6_ADDRSTRLEN]; // big enough for either IPv4 or IPv6
inet_ntop(AF_INET, &iaOriginal.s_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS A record: " << buf;
inet_ntop(AF_INET6, &v6prefix->sin6_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": NAT64 prefix: " << buf;
inet_ntop(AF_INET6, ia6, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS64 Synthesized AAAA record: " << buf;
}
}
hp->h_addrtype = AF_INET6;
hp->h_length = sizeof(in6_addr);
logDnsQueryResult(hp);
return true;
}
bool synthesizeNat64PrefixWithARecord(const netdutils::IPPrefix& prefix, addrinfo* result) {
if (result == nullptr) return false;
if (!onlyNonSpecialUseIPv4Addresses(result)) return false;
if (!isValidNat64Prefix(prefix)) return false;
struct sockaddr_storage ss = netdutils::IPSockAddr(prefix.ip());
struct sockaddr_in6* v6prefix = (struct sockaddr_in6*)&ss;
for (addrinfo* ai = result; ai; ai = ai->ai_next) {
struct sockaddr_in sinOriginal = *(struct sockaddr_in*)ai->ai_addr;
struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ai->ai_addr;
memset(sin6, 0, sizeof(sockaddr_in6));
// Synthesize /96 NAT64 prefix in place. The space has reserved by get_ai() in
// system/netd/resolv/getaddrinfo.cpp.
sin6->sin6_addr = v6prefix->sin6_addr;
sin6->sin6_addr.s6_addr32[3] = sinOriginal.sin_addr.s_addr;
sin6->sin6_family = AF_INET6;
sin6->sin6_port = sinOriginal.sin_port;
ai->ai_addrlen = sizeof(struct sockaddr_in6);
ai->ai_family = AF_INET6;
if (WOULD_LOG(VERBOSE)) {
char buf[INET6_ADDRSTRLEN]; // big enough for either IPv4 or IPv6
inet_ntop(AF_INET, &sinOriginal.sin_addr.s_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS A record: " << buf;
inet_ntop(AF_INET6, &v6prefix->sin6_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": NAT64 prefix: " << buf;
inet_ntop(AF_INET6, &sin6->sin6_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS64 Synthesized AAAA record: " << buf;
}
}
logDnsQueryResult(result);
return true;
}
bool getDns64Prefix(unsigned netId, netdutils::IPPrefix* prefix) {
return !gDnsResolv->resolverCtrl.getPrefix64(netId, prefix);
}
std::string makeThreadName(unsigned netId, uint32_t uid) {
// The maximum of netId and app_id are 5-digit numbers.
return fmt::format("Dns_{}_{}", netId, multiuser_get_app_id(uid));
}
} // namespace
DnsProxyListener::DnsProxyListener() : FrameworkListener(SOCKET_NAME) {
registerCmd(new GetAddrInfoCmd());
registerCmd(new GetHostByAddrCmd());
registerCmd(new GetHostByNameCmd());
registerCmd(new ResNSendCommand());
registerCmd(new GetDnsNetIdCommand());
}
void DnsProxyListener::Handler::spawn() {
const int rval = netdutils::threadLaunch(this);
if (rval == 0) {
return;
}
char* msg = nullptr;
asprintf(&msg, "%s (%d)", strerror(-rval), -rval);
mClient->sendMsg(ResponseCode::OperationFailed, msg, false);
free(msg);
delete this;
}
DnsProxyListener::GetAddrInfoHandler::GetAddrInfoHandler(SocketClient* c, std::string host,
std::string service,
std::unique_ptr<addrinfo> hints,
const android_net_context& netcontext)
: Handler(c),
mHost(move(host)),
mService(move(service)),
mHints(move(hints)),
mNetContext(netcontext) {}
static bool evaluate_domain_name(const android_net_context& netcontext, const char* host) {
if (!gResNetdCallbacks.evaluate_domain_name) return true;
return gResNetdCallbacks.evaluate_domain_name(netcontext, host);
}
static bool sendBE32(SocketClient* c, uint32_t data) {
uint32_t be_data = htonl(data);
return c->sendData(&be_data, sizeof(be_data)) == 0;
}
// Sends 4 bytes of big-endian length, followed by the data.
// Returns true on success.
static bool sendLenAndData(SocketClient* c, const int len, const void* data) {
return sendBE32(c, len) && (len == 0 || c->sendData(data, len) == 0);
}
// Returns true on success
static bool sendhostent(SocketClient* c, hostent* hp) {
bool success = true;
int i;
if (hp->h_name != nullptr) {
success &= sendLenAndData(c, strlen(hp->h_name) + 1, hp->h_name);
} else {
success &= sendLenAndData(c, 0, "") == 0;
}
for (i = 0; hp->h_aliases[i] != nullptr; i++) {
success &= sendLenAndData(c, strlen(hp->h_aliases[i]) + 1, hp->h_aliases[i]);
}
success &= sendLenAndData(c, 0, ""); // null to indicate we're done
uint32_t buf = htonl(hp->h_addrtype);
success &= c->sendData(&buf, sizeof(buf)) == 0;
buf = htonl(hp->h_length);
success &= c->sendData(&buf, sizeof(buf)) == 0;
for (i = 0; hp->h_addr_list[i] != nullptr; i++) {
success &= sendLenAndData(c, 16, hp->h_addr_list[i]);
}
success &= sendLenAndData(c, 0, ""); // null to indicate we're done
return success;
}
static bool sendaddrinfo(SocketClient* c, addrinfo* ai) {
// struct addrinfo {
// int ai_flags; /* AI_PASSIVE, AI_CANONNAME, AI_NUMERICHOST */
// int ai_family; /* PF_xxx */
// int ai_socktype; /* SOCK_xxx */
// int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
// socklen_t ai_addrlen; /* length of ai_addr */
// char *ai_canonname; /* canonical name for hostname */
// struct sockaddr *ai_addr; /* binary address */
// struct addrinfo *ai_next; /* next structure in linked list */
// };
// Write the struct piece by piece because we might be a 64-bit netd
// talking to a 32-bit process.
bool success = sendBE32(c, ai->ai_flags) && sendBE32(c, ai->ai_family) &&
sendBE32(c, ai->ai_socktype) && sendBE32(c, ai->ai_protocol);
if (!success) {
return false;
}
// ai_addrlen and ai_addr.
if (!sendLenAndData(c, ai->ai_addrlen, ai->ai_addr)) {
return false;
}
// strlen(ai_canonname) and ai_canonname.
if (!sendLenAndData(c, ai->ai_canonname ? strlen(ai->ai_canonname) + 1 : 0, ai->ai_canonname)) {
return false;
}
return true;
}
void DnsProxyListener::GetAddrInfoHandler::doDns64Synthesis(int32_t* rv, addrinfo** res,
NetworkDnsEventReported* event) {
const bool ipv6WantedButNoData = (mHints && mHints->ai_family == AF_INET6 && *rv == EAI_NODATA);
const bool unspecWantedButNoIPv6 =
((!mHints || mHints->ai_family == AF_UNSPEC) && *rv == 0 && onlyIPv4Answers(*res));
if (!ipv6WantedButNoData && !unspecWantedButNoIPv6) {
return;
}
netdutils::IPPrefix prefix{};
if (!getDns64Prefix(mNetContext.dns_netid, &prefix)) {
return;
}
if (ipv6WantedButNoData) {
// If caller wants IPv6 answers but no data, try to query IPv4 answers for synthesis
const uid_t uid = mClient->getUid();
if (queryLimiter.start(uid)) {
const char* host = mHost.starts_with('^') ? nullptr : mHost.c_str();
const char* service = mService.starts_with('^') ? nullptr : mService.c_str();
mHints->ai_family = AF_INET;
// Don't need to do freeaddrinfo(res) before starting new DNS lookup because previous
// DNS lookup is failed with error EAI_NODATA.
*rv = resolv_getaddrinfo(host, service, mHints.get(), &mNetContext, res, event);
queryLimiter.finish(uid);
if (*rv) {
*rv = EAI_NODATA; // return original error code
return;
}
} else {
LOG(ERROR) << __func__ << ": from UID " << uid << ", max concurrent queries reached";
return;
}
}
if (!synthesizeNat64PrefixWithARecord(prefix, *res)) {
if (ipv6WantedButNoData) {
// If caller wants IPv6 answers but no data and failed to synthesize IPv6 answers,
// don't return the IPv4 answers.
*rv = EAI_NODATA; // return original error code
if (*res) {
freeaddrinfo(*res);
*res = nullptr;
}
}
}
}
void DnsProxyListener::GetAddrInfoHandler::run() {
LOG(DEBUG) << "GetAddrInfoHandler::run: {" << mNetContext.app_netid << " "
<< mNetContext.app_mark << " " << mNetContext.dns_netid << " "
<< mNetContext.dns_mark << " " << mNetContext.uid << " " << mNetContext.flags << "}";
addrinfo* result = nullptr;
Stopwatch s;
maybeFixupNetContext(&mNetContext, mClient->getPid());
const uid_t uid = mClient->getUid();
int32_t rv = 0;
NetworkDnsEventReported event;
initDnsEvent(&event, mNetContext);
if (queryLimiter.start(uid)) {
const char* host = mHost.starts_with('^') ? nullptr : mHost.c_str();
const char* service = mService.starts_with('^') ? nullptr : mService.c_str();
if (evaluate_domain_name(mNetContext, host)) {
rv = resolv_getaddrinfo(host, service, mHints.get(), &mNetContext, &result, &event);
} else {
rv = EAI_SYSTEM;
}
queryLimiter.finish(uid);
} else {
// Note that this error code is currently not passed down to the client.
// android_getaddrinfo_proxy() returns EAI_NODATA on any error.
rv = EAI_MEMORY;
LOG(ERROR) << "GetAddrInfoHandler::run: from UID " << uid
<< ", max concurrent queries reached";
}
doDns64Synthesis(&rv, &result, &event);
const int32_t latencyUs = saturate_cast<int32_t>(s.timeTakenUs());
event.set_latency_micros(latencyUs);
event.set_event_type(EVENT_GETADDRINFO);
event.set_hints_ai_flags((mHints ? mHints->ai_flags : 0));
bool success = true;
if (rv) {
// getaddrinfo failed
success = !mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, &rv, sizeof(rv));
} else {
success = !mClient->sendCode(ResponseCode::DnsProxyQueryResult);
addrinfo* ai = result;
while (ai && success) {
success = sendBE32(mClient, 1) && sendaddrinfo(mClient, ai);
ai = ai->ai_next;
}
success = success && sendBE32(mClient, 0);
}
if (!success) {
PLOG(WARNING) << "GetAddrInfoHandler::run: Error writing DNS result to client uid " << uid
<< " pid " << mClient->getPid();
}
std::vector<std::string> ip_addrs;
const int total_ip_addr_count = extractGetAddrInfoAnswers(result, &ip_addrs);
reportDnsEvent(INetdEventListener::EVENT_GETADDRINFO, mNetContext, latencyUs, rv, event, mHost,
ip_addrs, total_ip_addr_count);
freeaddrinfo(result);
}
std::string DnsProxyListener::GetAddrInfoHandler::threadName() {
return makeThreadName(mNetContext.dns_netid, mClient->getUid());
}
namespace {
void addIpAddrWithinLimit(std::vector<std::string>* ip_addrs, const sockaddr* addr,
socklen_t addrlen) {
// ipAddresses array is limited to first INetdEventListener::DNS_REPORTED_IP_ADDRESSES_LIMIT
// addresses for A and AAAA. Total count of addresses is provided, to be able to tell whether
// some addresses didn't get logged.
if (ip_addrs->size() < INetdEventListener::DNS_REPORTED_IP_ADDRESSES_LIMIT) {
char ip_addr[INET6_ADDRSTRLEN];
if (getnameinfo(addr, addrlen, ip_addr, sizeof(ip_addr), nullptr, 0, NI_NUMERICHOST) == 0) {
ip_addrs->push_back(std::string(ip_addr));
}
}
}
} // namespace
DnsProxyListener::GetAddrInfoCmd::GetAddrInfoCmd() : FrameworkCommand("getaddrinfo") {}
int DnsProxyListener::GetAddrInfoCmd::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
if (argc != 8) {
char* msg = nullptr;
asprintf(&msg, "Invalid number of arguments to getaddrinfo: %i", argc);
LOG(WARNING) << "GetAddrInfoCmd::runCommand: " << (msg ? msg : "null");
cli->sendMsg(ResponseCode::CommandParameterError, msg, false);
free(msg);
return -1;
}
const std::string name = argv[1];
const std::string service = argv[2];
int ai_flags = strtol(argv[3], nullptr, 10);
int ai_family = strtol(argv[4], nullptr, 10);
int ai_socktype = strtol(argv[5], nullptr, 10);
int ai_protocol = strtol(argv[6], nullptr, 10);
unsigned netId = strtoul(argv[7], nullptr, 10);
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
const uid_t uid = cli->getUid();
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.flags |= NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
std::unique_ptr<addrinfo> hints;
if (ai_flags != -1 || ai_family != -1 || ai_socktype != -1 || ai_protocol != -1) {
hints.reset((addrinfo*)calloc(1, sizeof(addrinfo)));
hints->ai_flags = ai_flags;
hints->ai_family = ai_family;
hints->ai_socktype = ai_socktype;
hints->ai_protocol = ai_protocol;
}
(new GetAddrInfoHandler(cli, name, service, move(hints), netcontext))->spawn();
return 0;
}
/*******************************************************
* ResNSendCommand *
*******************************************************/
DnsProxyListener::ResNSendCommand::ResNSendCommand() : FrameworkCommand("resnsend") {}
int DnsProxyListener::ResNSendCommand::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
const uid_t uid = cli->getUid();
if (argc != 4) {
LOG(WARNING) << "ResNSendCommand::runCommand: resnsend: from UID " << uid
<< ", invalid number of arguments to resnsend: " << argc;
sendBE32(cli, -EINVAL);
return -1;
}
unsigned netId;
if (!simpleStrtoul(argv[1], &netId)) {
LOG(WARNING) << "ResNSendCommand::runCommand: resnsend: from UID " << uid
<< ", invalid netId";
sendBE32(cli, -EINVAL);
return -1;
}
uint32_t flags;
if (!simpleStrtoul(argv[2], &flags)) {
LOG(WARNING) << "ResNSendCommand::runCommand: resnsend: from UID " << uid
<< ", invalid flags";
sendBE32(cli, -EINVAL);
return -1;
}
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.flags |= NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
(new ResNSendHandler(cli, argv[3], flags, netcontext))->spawn();
return 0;
}
DnsProxyListener::ResNSendHandler::ResNSendHandler(SocketClient* c, std::string msg, uint32_t flags,
const android_net_context& netcontext)
: Handler(c), mMsg(std::move(msg)), mFlags(flags), mNetContext(netcontext) {}
void DnsProxyListener::ResNSendHandler::run() {
LOG(DEBUG) << "ResNSendHandler::run: " << mFlags << " / {" << mNetContext.app_netid << " "
<< mNetContext.app_mark << " " << mNetContext.dns_netid << " "
<< mNetContext.dns_mark << " " << mNetContext.uid << " " << mNetContext.flags << "}";
Stopwatch s;
maybeFixupNetContext(&mNetContext, mClient->getPid());
// Decode
std::vector<uint8_t> msg(MAXPACKET, 0);
// Max length of mMsg is less than 1024 since the CMD_BUF_SIZE in FrameworkListener is 1024
int msgLen = b64_pton(mMsg.c_str(), msg.data(), MAXPACKET);
if (msgLen == -1) {
// Decode fail
sendBE32(mClient, -EILSEQ);
return;
}
const uid_t uid = mClient->getUid();
int rr_type = 0;
std::string rr_name;
uint16_t original_query_id = 0;
// TODO: Handle the case which is msg contains more than one query
if (!parseQuery({msg.data(), msgLen}, &original_query_id, &rr_type, &rr_name) ||
!setQueryId({msg.data(), msgLen}, arc4random_uniform(65536))) {
// If the query couldn't be parsed, block the request.
LOG(WARNING) << "ResNSendHandler::run: resnsend: from UID " << uid << ", invalid query";
sendBE32(mClient, -EINVAL);
return;
}
// Send DNS query
std::vector<uint8_t> ansBuf(MAXPACKET, 0);
int rcode = ns_r_noerror;
int ansLen = -1;
NetworkDnsEventReported event;
initDnsEvent(&event, mNetContext);
if (queryLimiter.start(uid)) {
if (evaluate_domain_name(mNetContext, rr_name.c_str())) {
ansLen = resolv_res_nsend(&mNetContext, {msg.data(), msgLen}, ansBuf, &rcode,
static_cast<ResNsendFlags>(mFlags), &event);
} else {
ansLen = -EAI_SYSTEM;
}
queryLimiter.finish(uid);
} else {
LOG(WARNING) << "ResNSendHandler::run: resnsend: from UID " << uid
<< ", max concurrent queries reached";
ansLen = -EBUSY;
}
const int32_t latencyUs = saturate_cast<int32_t>(s.timeTakenUs());
event.set_latency_micros(latencyUs);
event.set_event_type(EVENT_RES_NSEND);
event.set_res_nsend_flags(static_cast<ResNsendFlags>(mFlags));
// Fail, send -errno
if (ansLen < 0) {
if (!sendBE32(mClient, ansLen)) {
PLOG(WARNING) << "ResNSendHandler::run: resnsend: failed to send errno to uid " << uid
<< " pid " << mClient->getPid();
}
if (rr_type == ns_t_a || rr_type == ns_t_aaaa) {
reportDnsEvent(INetdEventListener::EVENT_RES_NSEND, mNetContext, latencyUs,
resNSendToAiError(ansLen, rcode), event, rr_name);
}
return;
}
// Send rcode
if (!sendBE32(mClient, rcode)) {
PLOG(WARNING) << "ResNSendHandler::run: resnsend: failed to send rcode to uid " << uid
<< " pid " << mClient->getPid();
return;
}
// Restore query id and send answer
if (!setQueryId({ansBuf.data(), ansLen}, original_query_id) ||
!sendLenAndData(mClient, ansLen, ansBuf.data())) {
PLOG(WARNING) << "ResNSendHandler::run: resnsend: failed to send answer to uid " << uid
<< " pid " << mClient->getPid();
return;
}
if (rr_type == ns_t_a || rr_type == ns_t_aaaa) {
std::vector<std::string> ip_addrs;
const int total_ip_addr_count =
extractResNsendAnswers({ansBuf.data(), ansLen}, rr_type, &ip_addrs);
reportDnsEvent(INetdEventListener::EVENT_RES_NSEND, mNetContext, latencyUs,
resNSendToAiError(ansLen, rcode), event, rr_name, ip_addrs,
total_ip_addr_count);
}
}
std::string DnsProxyListener::ResNSendHandler::threadName() {