summaryrefslogtreecommitdiff
path: root/src/resolve/resolved-dns-dnssec.c
blob: 2202daafc0eb3f01f310c59988dcd47475741cfc (plain)
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2015 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <gcrypt.h>

#include "alloc-util.h"
#include "dns-domain.h"
#include "hexdecoct.h"
#include "resolved-dns-dnssec.h"
#include "resolved-dns-packet.h"
#include "string-table.h"

/* Open question:
 *
 * How does the DNSSEC canonical form of a hostname with a label
 * containing a dot look like, the way DNS-SD does it?
 *
 * TODO:
 *
 *   - wildcard zones compatibility (NSEC/NSEC3 wildcard check is missing)
 *   - multi-label zone compatibility
 *   - cname/dname compatibility
 *   - nxdomain on qname
 *   - bus calls to override DNSEC setting per interface
 *   - log all DNSSEC downgrades
 *   - enable by default
 *
 *   - RFC 4035, Section 5.3.4 (When receiving a positive wildcard reply, use NSEC to ensure it actually really applies)
 *   - RFC 6840, Section 4.1 (ensure we don't get fed a glue NSEC from the parent zone)
 *   - RFC 6840, Section 4.3 (check for CNAME on NSEC too)
 * */

#define VERIFY_RRS_MAX 256
#define MAX_KEY_SIZE (32*1024)

/* Permit a maximum clock skew of 1h 10min. This should be enough to deal with DST confusion */
#define SKEW_MAX (1*USEC_PER_HOUR + 10*USEC_PER_MINUTE)

/* Maximum number of NSEC3 iterations we'll do. RFC5155 says 2500 shall be the maximum useful value */
#define NSEC3_ITERATIONS_MAX 2500

/*
 * The DNSSEC Chain of trust:
 *
 *            Normal RRs are protected via RRSIG RRs in combination with DNSKEY RRs, all in the same zone
 *            DNSKEY RRs are either protected like normal RRs, or via a DS from a zone "higher" up the tree
 *            DS RRs are protected like normal RRs
 *
 * Example chain:
 *            Normal RR → RRSIG/DNSKEY+ → DS → RRSIG/DNSKEY+ → DS → ... → DS → RRSIG/DNSKEY+ → DS
 */

static void initialize_libgcrypt(void) {
        const char *p;

        if (gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P))
                return;

        p = gcry_check_version("1.4.5");
        assert(p);

        gcry_control(GCRYCTL_DISABLE_SECMEM);
        gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
}

uint16_t dnssec_keytag(DnsResourceRecord *dnskey, bool mask_revoke) {
        const uint8_t *p;
        uint32_t sum, f;
        size_t i;

        /* The algorithm from RFC 4034, Appendix B. */

        assert(dnskey);
        assert(dnskey->key->type == DNS_TYPE_DNSKEY);

        f = (uint32_t) dnskey->dnskey.flags;

        if (mask_revoke)
                f &= ~DNSKEY_FLAG_REVOKE;

        sum = f + ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);

        p = dnskey->dnskey.key;

        for (i = 0; i < dnskey->dnskey.key_size; i++)
                sum += (i & 1) == 0 ? (uint32_t) p[i] << 8 : (uint32_t) p[i];

        sum += (sum >> 16) & UINT32_C(0xFFFF);

        return sum & UINT32_C(0xFFFF);
}

static int rr_compare(const void *a, const void *b) {
        DnsResourceRecord **x = (DnsResourceRecord**) a, **y = (DnsResourceRecord**) b;
        size_t m;
        int r;

        /* Let's order the RRs according to RFC 4034, Section 6.3 */

        assert(x);
        assert(*x);
        assert((*x)->wire_format);
        assert(y);
        assert(*y);
        assert((*y)->wire_format);

        m = MIN(DNS_RESOURCE_RECORD_RDATA_SIZE(*x), DNS_RESOURCE_RECORD_RDATA_SIZE(*y));

        r = memcmp(DNS_RESOURCE_RECORD_RDATA(*x), DNS_RESOURCE_RECORD_RDATA(*y), m);
        if (r != 0)
                return r;

        if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) < DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
                return -1;
        else if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) > DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
                return 1;

        return 0;
}

static int dnssec_rsa_verify_raw(
                const char *hash_algorithm,
                const void *signature, size_t signature_size,
                const void *data, size_t data_size,
                const void *exponent, size_t exponent_size,
                const void *modulus, size_t modulus_size) {

        gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;
        gcry_mpi_t n = NULL, e = NULL, s = NULL;
        gcry_error_t ge;
        int r;

        assert(hash_algorithm);

        ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature, signature_size, NULL);
        if (ge != 0) {
                r = -EIO;
                goto finish;
        }

        ge = gcry_mpi_scan(&e, GCRYMPI_FMT_USG, exponent, exponent_size, NULL);
        if (ge != 0) {
                r = -EIO;
                goto finish;
        }

        ge = gcry_mpi_scan(&n, GCRYMPI_FMT_USG, modulus, modulus_size, NULL);
        if (ge != 0) {
                r = -EIO;
                goto finish;
        }

        ge = gcry_sexp_build(&signature_sexp,
                             NULL,
                             "(sig-val (rsa (s %m)))",
                             s);

        if (ge != 0) {
                r = -EIO;
                goto finish;
        }

        ge = gcry_sexp_build(&data_sexp,
                             NULL,
                             "(data (flags pkcs1) (hash %s %b))",
                             hash_algorithm,
                             (int) data_size,
                             data);
        if (ge != 0) {
                r = -EIO;
                goto finish;
        }

        ge = gcry_sexp_build(&public_key_sexp,
                             NULL,
                             "(public-key (rsa (n %m) (e %m)))",
                             n,
                             e);
        if (ge != 0) {
                r = -EIO;
                goto finish;
        }

        ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);
        if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)
                r = 0;
        else if (ge != 0) {
                log_debug("RSA signature check failed: %s", gpg_strerror(ge));
                r = -EIO;
        } else
                r = 1;

finish:
        if (e)
                gcry_mpi_release(e);
        if (n)
                gcry_mpi_release(n);
        if (s)
                gcry_mpi_release(s);

        if (public_key_sexp)
                gcry_sexp_release(public_key_sexp);
        if (signature_sexp)
                gcry_sexp_release(signature_sexp);
        if (data_sexp)
                gcry_sexp_release(data_sexp);

        return r;
}

static int dnssec_rsa_verify(
                const char *hash_algorithm,
                const void *hash, size_t hash_size,
                DnsResourceRecord *rrsig,
                DnsResourceRecord *dnskey) {

        size_t exponent_size, modulus_size;
        void *exponent, *modulus;

        assert(hash_algorithm);
        assert(hash);
        assert(hash_size > 0);
        assert(rrsig);
        assert(dnskey);

        if (*(uint8_t*) dnskey->dnskey.key == 0) {
                /* exponent is > 255 bytes long */

                exponent = (uint8_t*) dnskey->dnskey.key + 3;
                exponent_size =
                        ((size_t) (((uint8_t*) dnskey->dnskey.key)[1]) << 8) |
                        ((size_t) ((uint8_t*) dnskey->dnskey.key)[2]);

                if (exponent_size < 256)
                        return -EINVAL;

                if (3 + exponent_size >= dnskey->dnskey.key_size)
                        return -EINVAL;

                modulus = (uint8_t*) dnskey->dnskey.key + 3 + exponent_size;
                modulus_size = dnskey->dnskey.key_size - 3 - exponent_size;

        } else {
                /* exponent is <= 255 bytes long */

                exponent = (uint8_t*) dnskey->dnskey.key + 1;
                exponent_size = (size_t) ((uint8_t*) dnskey->dnskey.key)[0];

                if (exponent_size <= 0)
                        return -EINVAL;

                if (1 + exponent_size >= dnskey->dnskey.key_size)
                        return -EINVAL;

                modulus = (uint8_t*) dnskey->dnskey.key + 1 + exponent_size;
                modulus_size = dnskey->dnskey.key_size - 1 - exponent_size;
        }

        return dnssec_rsa_verify_raw(
                        hash_algorithm,
                        rrsig->rrsig.signature, rrsig->rrsig.signature_size,
                        hash, hash_size,
                        exponent, exponent_size,
                        modulus, modulus_size);
}

static int dnssec_ecdsa_verify_raw(
                const char *hash_algorithm,
                const char *curve,
                const void *signature_r, size_t signature_r_size,
                const void *signature_s, size_t signature_s_size,
                const void *data, size_t data_size,
                const void *key, size_t key_size) {

        gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;
        gcry_mpi_t q = NULL, r = NULL, s = NULL;
        gcry_error_t ge;
        int k;

        assert(hash_algorithm);

        ge = gcry_mpi_scan(&r, GCRYMPI_FMT_USG, signature_r, signature_r_size, NULL);
        if (ge != 0) {
                k = -EIO;
                goto finish;
        }

        ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature_s, signature_s_size, NULL);
        if (ge != 0) {
                k = -EIO;
                goto finish;
        }

        ge = gcry_mpi_scan(&q, GCRYMPI_FMT_USG, key, key_size, NULL);
        if (ge != 0) {
                k = -EIO;
                goto finish;
        }

        ge = gcry_sexp_build(&signature_sexp,
                             NULL,
                             "(sig-val (ecdsa (r %m) (s %m)))",
                             r,
                             s);
        if (ge != 0) {
                k = -EIO;
                goto finish;
        }

        ge = gcry_sexp_build(&data_sexp,
                             NULL,
                             "(data (flags rfc6979) (hash %s %b))",
                             hash_algorithm,
                             (int) data_size,
                             data);
        if (ge != 0) {
                k = -EIO;
                goto finish;
        }

        ge = gcry_sexp_build(&public_key_sexp,
                             NULL,
                             "(public-key (ecc (curve %s) (q %m)))",
                             curve,
                             q);
        if (ge != 0) {
                k = -EIO;
                goto finish;
        }

        ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);
        if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)
                k = 0;
        else if (ge != 0) {
                log_debug("ECDSA signature check failed: %s", gpg_strerror(ge));
                k = -EIO;
        } else
                k = 1;
finish:
        if (r)
                gcry_mpi_release(r);
        if (s)
                gcry_mpi_release(s);
        if (q)
                gcry_mpi_release(q);

        if (public_key_sexp)
                gcry_sexp_release(public_key_sexp);
        if (signature_sexp)
                gcry_sexp_release(signature_sexp);
        if (data_sexp)
                gcry_sexp_release(data_sexp);

        return k;
}

static int dnssec_ecdsa_verify(
                const char *hash_algorithm,
                int algorithm,
                const void *hash, size_t hash_size,
                DnsResourceRecord *rrsig,
                DnsResourceRecord *dnskey) {

        const char *curve;
        size_t key_size;
        uint8_t *q;

        assert(hash);
        assert(hash_size);
        assert(rrsig);
        assert(dnskey);

        if (algorithm == DNSSEC_ALGORITHM_ECDSAP256SHA256) {
                key_size = 32;
                curve = "NIST P-256";
        } else if (algorithm == DNSSEC_ALGORITHM_ECDSAP384SHA384) {
                key_size = 48;
                curve = "NIST P-384";
        } else
                return -EOPNOTSUPP;

        if (dnskey->dnskey.key_size != key_size * 2)
                return -EINVAL;

        if (rrsig->rrsig.signature_size != key_size * 2)
                return -EINVAL;

        q = alloca(key_size*2 + 1);
        q[0] = 0x04; /* Prepend 0x04 to indicate an uncompressed key */
        memcpy(q+1, dnskey->dnskey.key, key_size*2);

        return dnssec_ecdsa_verify_raw(
                        hash_algorithm,
                        curve,
                        rrsig->rrsig.signature, key_size,
                        (uint8_t*) rrsig->rrsig.signature + key_size, key_size,
                        hash, hash_size,
                        q, key_size*2+1);
}

static void md_add_uint8(gcry_md_hd_t md, uint8_t v) {
        gcry_md_write(md, &v, sizeof(v));
}

static void md_add_uint16(gcry_md_hd_t md, uint16_t v) {
        v = htobe16(v);
        gcry_md_write(md, &v, sizeof(v));
}

static void md_add_uint32(gcry_md_hd_t md, uint32_t v) {
        v = htobe32(v);
        gcry_md_write(md, &v, sizeof(v));
}

static int dnssec_rrsig_prepare(DnsResourceRecord *rrsig) {
        int n_key_labels, n_signer_labels;
        const char *name;
        int r;

        /* Checks whether the specified RRSIG RR is somewhat valid, and initializes the .n_skip_labels_source and
         * .n_skip_labels_signer fields so that we can use them later on. */

        assert(rrsig);
        assert(rrsig->key->type == DNS_TYPE_RRSIG);

        /* Check if this RRSIG RR is already prepared */
        if (rrsig->n_skip_labels_source != (unsigned) -1)
                return 0;

        if (rrsig->rrsig.inception > rrsig->rrsig.expiration)
                return -EINVAL;

        name = DNS_RESOURCE_KEY_NAME(rrsig->key);

        n_key_labels = dns_name_count_labels(name);
        if (n_key_labels < 0)
                return n_key_labels;
        if (rrsig->rrsig.labels > n_key_labels)
                return -EINVAL;

        n_signer_labels = dns_name_count_labels(rrsig->rrsig.signer);
        if (n_signer_labels < 0)
                return n_signer_labels;
        if (n_signer_labels > rrsig->rrsig.labels)
                return -EINVAL;

        r = dns_name_skip(name, n_key_labels - n_signer_labels, &name);
        if (r < 0)
                return r;
        if (r == 0)
                return -EINVAL;

        /* Check if the signer is really a suffix of us */
        r = dns_name_equal(name, rrsig->rrsig.signer);
        if (r < 0)
                return r;
        if (r == 0)
                return -EINVAL;

        rrsig->n_skip_labels_source = n_key_labels - rrsig->rrsig.labels;
        rrsig->n_skip_labels_signer = n_key_labels - n_signer_labels;

        return 0;
}

static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {
        usec_t expiration, inception, skew;

        assert(rrsig);
        assert(rrsig->key->type == DNS_TYPE_RRSIG);

        if (realtime == USEC_INFINITY)
                realtime = now(CLOCK_REALTIME);

        expiration = rrsig->rrsig.expiration * USEC_PER_SEC;
        inception = rrsig->rrsig.inception * USEC_PER_SEC;

        /* Consider inverted validity intervals as expired */
        if (inception > expiration)
                return true;

        /* Permit a certain amount of clock skew of 10% of the valid
         * time range. This takes inspiration from unbound's
         * resolver. */
        skew = (expiration - inception) / 10;
        if (skew > SKEW_MAX)
                skew = SKEW_MAX;

        if (inception < skew)
                inception = 0;
        else
                inception -= skew;

        if (expiration + skew < expiration)
                expiration = USEC_INFINITY;
        else
                expiration += skew;

        return realtime < inception || realtime > expiration;
}

static int algorithm_to_gcrypt_md(uint8_t algorithm) {

        /* Translates a DNSSEC signature algorithm into a gcrypt
         * digest identifier.
         *
         * Note that we implement all algorithms listed as "Must
         * implement" and "Recommended to Implement" in RFC6944. We
         * don't implement any algorithms that are listed as
         * "Optional" or "Must Not Implement". Specifically, we do not
         * implement RSAMD5, DSASHA1, DH, DSA-NSEC3-SHA1, and
         * GOST-ECC. */

        switch (algorithm) {

        case DNSSEC_ALGORITHM_RSASHA1:
        case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
                return GCRY_MD_SHA1;

        case DNSSEC_ALGORITHM_RSASHA256:
        case DNSSEC_ALGORITHM_ECDSAP256SHA256:
                return GCRY_MD_SHA256;

        case DNSSEC_ALGORITHM_ECDSAP384SHA384:
                return GCRY_MD_SHA384;

        case DNSSEC_ALGORITHM_RSASHA512:
                return GCRY_MD_SHA512;

        default:
                return -EOPNOTSUPP;
        }
}

static void dnssec_fix_rrset_ttl(
                DnsResourceRecord *list[],
                unsigned n,
                DnsResourceRecord *rrsig,
                usec_t realtime) {

        unsigned k;

        assert(list);
        assert(n > 0);
        assert(rrsig);

        for (k = 0; k < n; k++) {
                DnsResourceRecord *rr = list[k];

                /* Pick the TTL as the minimum of the RR's TTL, the
                 * RR's original TTL according to the RRSIG and the
                 * RRSIG's own TTL, see RFC 4035, Section 5.3.3 */
                rr->ttl = MIN3(rr->ttl, rrsig->rrsig.original_ttl, rrsig->ttl);
                rr->expiry = rrsig->rrsig.expiration * USEC_PER_SEC;

                /* Copy over information about the signer and wildcard source of synthesis */
                rr->n_skip_labels_source = rrsig->n_skip_labels_source;
                rr->n_skip_labels_signer = rrsig->n_skip_labels_signer;
        }

        rrsig->expiry = rrsig->rrsig.expiration * USEC_PER_SEC;
}

int dnssec_verify_rrset(
                DnsAnswer *a,
                const DnsResourceKey *key,
                DnsResourceRecord *rrsig,
                DnsResourceRecord *dnskey,
                usec_t realtime,
                DnssecResult *result) {

        uint8_t wire_format_name[DNS_WIRE_FOMAT_HOSTNAME_MAX];
        DnsResourceRecord **list, *rr;
        const char *source, *name;
        gcry_md_hd_t md = NULL;
        int r, md_algorithm;
        size_t k, n = 0;
        size_t hash_size;
        void *hash;
        bool wildcard;

        assert(key);
        assert(rrsig);
        assert(dnskey);
        assert(result);
        assert(rrsig->key->type == DNS_TYPE_RRSIG);
        assert(dnskey->key->type == DNS_TYPE_DNSKEY);

        /* Verifies the the RRSet matching the specified "key" in "a",
         * using the signature "rrsig" and the key "dnskey". It's
         * assumed the RRSIG and DNSKEY match. */

        md_algorithm = algorithm_to_gcrypt_md(rrsig->rrsig.algorithm);
        if (md_algorithm == -EOPNOTSUPP) {
                *result = DNSSEC_UNSUPPORTED_ALGORITHM;
                return 0;
        }
        if (md_algorithm < 0)
                return md_algorithm;

        r = dnssec_rrsig_prepare(rrsig);
        if (r == -EINVAL) {
                *result = DNSSEC_INVALID;
                return r;
        }
        if (r < 0)
                return r;

        r = dnssec_rrsig_expired(rrsig, realtime);
        if (r < 0)
                return r;
        if (r > 0) {
                *result = DNSSEC_SIGNATURE_EXPIRED;
                return 0;
        }

        name = DNS_RESOURCE_KEY_NAME(key);

        /* Some keys may only appear signed in the zone apex, and are invalid anywhere else. (SOA, NS...) */
        if (dns_type_apex_only(rrsig->rrsig.type_covered)) {
                r = dns_name_equal(rrsig->rrsig.signer, name);
                if (r < 0)
                        return r;
                if (r == 0) {
                        *result = DNSSEC_INVALID;
                        return 0;
                }
        }

        /* OTOH DS RRs may not appear in the zone apex, but are valid everywhere else. */
        if (rrsig->rrsig.type_covered == DNS_TYPE_DS) {
                r = dns_name_equal(rrsig->rrsig.signer, name);
                if (r < 0)
                        return r;
                if (r > 0) {
                        *result = DNSSEC_INVALID;
                        return 0;
                }
        }

        /* Determine the "Source of Synthesis" and whether this is a wildcard RRSIG */
        r = dns_name_suffix(name, rrsig->rrsig.labels, &source);
        if (r < 0)
                return r;
        if (r > 0 && !dns_type_may_wildcard(rrsig->rrsig.type_covered)) {
                /* We refuse to validate NSEC3 or SOA RRs that are synthesized from wildcards */
                *result = DNSSEC_INVALID;
                return 0;
        }
        if (r == 1) {
                /* If we stripped a single label, then let's see if that maybe was "*". If so, we are not really
                 * synthesized from a wildcard, we are the wildcard itself. Treat that like a normal name. */
                r = dns_name_startswith(name, "*");
                if (r < 0)
                        return r;
                if (r > 0)
                        source = name;

                wildcard = r == 0;
        } else
                wildcard = r > 0;

        /* Collect all relevant RRs in a single array, so that we can look at the RRset */
        list = newa(DnsResourceRecord *, dns_answer_size(a));

        DNS_ANSWER_FOREACH(rr, a) {
                r = dns_resource_key_equal(key, rr->key);
                if (r < 0)
                        return r;
                if (r == 0)
                        continue;

                /* We need the wire format for ordering, and digest calculation */
                r = dns_resource_record_to_wire_format(rr, true);
                if (r < 0)
                        return r;

                list[n++] = rr;

                if (n > VERIFY_RRS_MAX)
                        return -E2BIG;
        }

        if (n <= 0)
                return -ENODATA;

        /* Bring the RRs into canonical order */
        qsort_safe(list, n, sizeof(DnsResourceRecord*), rr_compare);

        /* OK, the RRs are now in canonical order. Let's calculate the digest */
        initialize_libgcrypt();

        hash_size = gcry_md_get_algo_dlen(md_algorithm);
        assert(hash_size > 0);

        gcry_md_open(&md, md_algorithm, 0);
        if (!md)
                return -EIO;

        md_add_uint16(md, rrsig->rrsig.type_covered);
        md_add_uint8(md, rrsig->rrsig.algorithm);
        md_add_uint8(md, rrsig->rrsig.labels);
        md_add_uint32(md, rrsig->rrsig.original_ttl);
        md_add_uint32(md, rrsig->rrsig.expiration);
        md_add_uint32(md, rrsig->rrsig.inception);
        md_add_uint16(md, rrsig->rrsig.key_tag);

        r = dns_name_to_wire_format(rrsig->rrsig.signer, wire_format_name, sizeof(wire_format_name), true);
        if (r < 0)
                goto finish;
        gcry_md_write(md, wire_format_name, r);

        /* Convert the source of synthesis into wire format */
        r = dns_name_to_wire_format(source, wire_format_name, sizeof(wire_format_name), true);
        if (r < 0)
                goto finish;

        for (k = 0; k < n; k++) {
                size_t l;

                rr = list[k];

                /* Hash the source of synthesis. If this is a wildcard, then prefix it with the *. label */
                if (wildcard)
                        gcry_md_write(md, (uint8_t[]) { 1, '*'}, 2);
                gcry_md_write(md, wire_format_name, r);

                md_add_uint16(md, rr->key->type);
                md_add_uint16(md, rr->key->class);
                md_add_uint32(md, rrsig->rrsig.original_ttl);

                l = DNS_RESOURCE_RECORD_RDATA_SIZE(rr);
                assert(l <= 0xFFFF);

                md_add_uint16(md, (uint16_t) l);
                gcry_md_write(md, DNS_RESOURCE_RECORD_RDATA(rr), l);
        }

        hash = gcry_md_read(md, 0);
        if (!hash) {
                r = -EIO;
                goto finish;
        }

        switch (rrsig->rrsig.algorithm) {

        case DNSSEC_ALGORITHM_RSASHA1:
        case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
        case DNSSEC_ALGORITHM_RSASHA256:
        case DNSSEC_ALGORITHM_RSASHA512:
                r = dnssec_rsa_verify(
                                gcry_md_algo_name(md_algorithm),
                                hash, hash_size,
                                rrsig,
                                dnskey);
                break;

        case DNSSEC_ALGORITHM_ECDSAP256SHA256:
        case DNSSEC_ALGORITHM_ECDSAP384SHA384:
                r = dnssec_ecdsa_verify(
                                gcry_md_algo_name(md_algorithm),
                                rrsig->rrsig.algorithm,
                                hash, hash_size,
                                rrsig,
                                dnskey);
                break;
        }

        if (r < 0)
                goto finish;

        /* Now, fix the ttl, expiry, and remember the synthesizing source and the signer */
        if (r > 0)
                dnssec_fix_rrset_ttl(list, n, rrsig, realtime);

        if (r == 0)
                *result = DNSSEC_INVALID;
        else if (wildcard)
                *result = DNSSEC_VALIDATED_WILDCARD;
        else
                *result = DNSSEC_VALIDATED;

        r = 0;

finish:
        gcry_md_close(md);
        return r;
}

int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, bool revoked_ok) {

        assert(rrsig);
        assert(dnskey);

        /* Checks if the specified DNSKEY RR matches the key used for
         * the signature in the specified RRSIG RR */

        if (rrsig->key->type != DNS_TYPE_RRSIG)
                return -EINVAL;

        if (dnskey->key->type != DNS_TYPE_DNSKEY)
                return 0;
        if (dnskey->key->class != rrsig->key->class)
                return 0;
        if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
                return 0;
        if (!revoked_ok && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))
                return 0;
        if (dnskey->dnskey.protocol != 3)
                return 0;
        if (dnskey->dnskey.algorithm != rrsig->rrsig.algorithm)
                return 0;

        if (dnssec_keytag(dnskey, false) != rrsig->rrsig.key_tag)
                return 0;

        return dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), rrsig->rrsig.signer);
}

int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) {
        assert(key);
        assert(rrsig);

        /* Checks if the specified RRSIG RR protects the RRSet of the specified RR key. */

        if (rrsig->key->type != DNS_TYPE_RRSIG)
                return 0;
        if (rrsig->key->class != key->class)
                return 0;
        if (rrsig->rrsig.type_covered != key->type)
                return 0;

        return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key));
}

int dnssec_verify_rrset_search(
                DnsAnswer *a,
                const DnsResourceKey *key,
                DnsAnswer *validated_dnskeys,
                usec_t realtime,
                DnssecResult *result,
                DnsResourceRecord **ret_rrsig) {

        bool found_rrsig = false, found_invalid = false, found_expired_rrsig = false, found_unsupported_algorithm = false;
        DnsResourceRecord *rrsig;
        int r;

        assert(key);
        assert(result);

        /* Verifies all RRs from "a" that match the key "key" against DNSKEYs in "validated_dnskeys" */

        if (!a || a->n_rrs <= 0)
                return -ENODATA;

        /* Iterate through each RRSIG RR. */
        DNS_ANSWER_FOREACH(rrsig, a) {
                DnsResourceRecord *dnskey;
                DnsAnswerFlags flags;

                /* Is this an RRSIG RR that applies to RRs matching our key? */
                r = dnssec_key_match_rrsig(key, rrsig);
                if (r < 0)
                        return r;
                if (r == 0)
                        continue;

                found_rrsig = true;

                /* Look for a matching key */
                DNS_ANSWER_FOREACH_FLAGS(dnskey, flags, validated_dnskeys) {
                        DnssecResult one_result;

                        if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
                                continue;

                        /* Is this a DNSKEY RR that matches they key of our RRSIG? */
                        r = dnssec_rrsig_match_dnskey(rrsig, dnskey, false);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                continue;

                        /* Take the time here, if it isn't set yet, so
                         * that we do all validations with the same
                         * time. */
                        if (realtime == USEC_INFINITY)
                                realtime = now(CLOCK_REALTIME);

                        /* Yay, we found a matching RRSIG with a matching
                         * DNSKEY, awesome. Now let's verify all entries of
                         * the RRSet against the RRSIG and DNSKEY
                         * combination. */

                        r = dnssec_verify_rrset(a, key, rrsig, dnskey, realtime, &one_result);
                        if (r < 0)
                                return r;

                        switch (one_result) {

                        case DNSSEC_VALIDATED:
                        case DNSSEC_VALIDATED_WILDCARD:
                                /* Yay, the RR has been validated,
                                 * return immediately, but fix up the expiry */
                                if (ret_rrsig)
                                        *ret_rrsig = rrsig;

                                *result = one_result;
                                return 0;

                        case DNSSEC_INVALID:
                                /* If the signature is invalid, let's try another
                                   key and/or signature. After all they
                                   key_tags and stuff are not unique, and
                                   might be shared by multiple keys. */
                                found_invalid = true;
                                continue;

                        case DNSSEC_UNSUPPORTED_ALGORITHM:
                                /* If the key algorithm is
                                   unsupported, try another
                                   RRSIG/DNSKEY pair, but remember we
                                   encountered this, so that we can
                                   return a proper error when we
                                   encounter nothing better. */
                                found_unsupported_algorithm = true;
                                continue;

                        case DNSSEC_SIGNATURE_EXPIRED:
                                /* If the signature is expired, try
                                   another one, but remember it, so
                                   that we can return this */
                                found_expired_rrsig = true;
                                continue;

                        default:
                                assert_not_reached("Unexpected DNSSEC validation result");
                        }
                }
        }

        if (found_expired_rrsig)
                *result = DNSSEC_SIGNATURE_EXPIRED;
        else if (found_unsupported_algorithm)
                *result = DNSSEC_UNSUPPORTED_ALGORITHM;
        else if (found_invalid)
                *result = DNSSEC_INVALID;
        else if (found_rrsig)
                *result = DNSSEC_MISSING_KEY;
        else
                *result = DNSSEC_NO_SIGNATURE;

        if (ret_rrsig)
                *ret_rrsig = NULL;

        return 0;
}

int dnssec_has_rrsig(DnsAnswer *a, const DnsResourceKey *key) {
        DnsResourceRecord *rr;
        int r;

        /* Checks whether there's at least one RRSIG in 'a' that proctects RRs of the specified key */

        DNS_ANSWER_FOREACH(rr, a) {
                r = dnssec_key_match_rrsig(key, rr);
                if (r < 0)
                        return r;
                if (r > 0)
                        return 1;
        }

        return 0;
}

int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) {
        size_t c = 0;
        int r;

        /* Converts the specified hostname into DNSSEC canonicalized
         * form. */

        if (buffer_max < 2)
                return -ENOBUFS;

        for (;;) {
                r = dns_label_unescape(&n, buffer, buffer_max);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;
                if (r > 0) {
                        int k;

                        /* DNSSEC validation is always done on the ASCII version of the label */
                        k = dns_label_apply_idna(buffer, r, buffer, buffer_max);
                        if (k < 0)
                                return k;
                        if (k > 0)
                                r = k;
                }

                if (buffer_max < (size_t) r + 2)
                        return -ENOBUFS;

                /* The DNSSEC canonical form is not clear on what to
                 * do with dots appearing in labels, the way DNS-SD
                 * does it. Refuse it for now. */

                if (memchr(buffer, '.', r))
                        return -EINVAL;

                ascii_strlower_n(buffer, (size_t) r);
                buffer[r] = '.';

                buffer += r + 1;
                c += r + 1;

                buffer_max -= r + 1;
        }

        if (c <= 0) {
                /* Not even a single label: this is the root domain name */

                assert(buffer_max > 2);
                buffer[0] = '.';
                buffer[1] = 0;

                return 1;
        }

        return (int) c;
}

static int digest_to_gcrypt_md(uint8_t algorithm) {

        /* Translates a DNSSEC digest algorithm into a gcrypt digest identifier */

        switch (algorithm) {

        case DNSSEC_DIGEST_SHA1:
                return GCRY_MD_SHA1;

        case DNSSEC_DIGEST_SHA256:
                return GCRY_MD_SHA256;

        case DNSSEC_DIGEST_SHA384:
                return GCRY_MD_SHA384;

        default:
                return -EOPNOTSUPP;
        }
}

int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) {
        char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX];
        gcry_md_hd_t md = NULL;
        size_t hash_size;
        int md_algorithm, r;
        void *result;

        assert(dnskey);
        assert(ds);

        /* Implements DNSKEY verification by a DS, according to RFC 4035, section 5.2 */

        if (dnskey->key->type != DNS_TYPE_DNSKEY)
                return -EINVAL;
        if (ds->key->type != DNS_TYPE_DS)
                return -EINVAL;
        if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
                return -EKEYREJECTED;
        if (!mask_revoke && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))
                return -EKEYREJECTED;
        if (dnskey->dnskey.protocol != 3)
                return -EKEYREJECTED;

        if (dnskey->dnskey.algorithm != ds->ds.algorithm)
                return 0;
        if (dnssec_keytag(dnskey, mask_revoke) != ds->ds.key_tag)
                return 0;

        initialize_libgcrypt();

        md_algorithm = digest_to_gcrypt_md(ds->ds.digest_type);
        if (md_algorithm < 0)
                return md_algorithm;

        hash_size = gcry_md_get_algo_dlen(md_algorithm);
        assert(hash_size > 0);

        if (ds->ds.digest_size != hash_size)
                return 0;

        r = dnssec_canonicalize(DNS_RESOURCE_KEY_NAME(dnskey->key), owner_name, sizeof(owner_name));
        if (r < 0)
                return r;

        gcry_md_open(&md, md_algorithm, 0);
        if (!md)
                return -EIO;

        gcry_md_write(md, owner_name, r);
        if (mask_revoke)
                md_add_uint16(md, dnskey->dnskey.flags & ~DNSKEY_FLAG_REVOKE);
        else
                md_add_uint16(md, dnskey->dnskey.flags);
        md_add_uint8(md, dnskey->dnskey.protocol);
        md_add_uint8(md, dnskey->dnskey.algorithm);
        gcry_md_write(md, dnskey->dnskey.key, dnskey->dnskey.key_size);

        result = gcry_md_read(md, 0);
        if (!result) {
                r = -EIO;
                goto finish;
        }

        r = memcmp(result, ds->ds.digest, ds->ds.digest_size) != 0;

finish:
        gcry_md_close(md);
        return r;
}

int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) {
        DnsResourceRecord *ds;
        DnsAnswerFlags flags;
        int r;

        assert(dnskey);

        if (dnskey->key->type != DNS_TYPE_DNSKEY)
                return 0;

        DNS_ANSWER_FOREACH_FLAGS(ds, flags, validated_ds) {

                if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
                        continue;

                if (ds->key->type != DNS_TYPE_DS)
                        continue;
                if (ds->key->class != dnskey->key->class)
                        continue;

                r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), DNS_RESOURCE_KEY_NAME(ds->key));
                if (r < 0)
                        return r;
                if (r == 0)
                        continue;

                r = dnssec_verify_dnskey(dnskey, ds, false);
                if (IN_SET(r, -EKEYREJECTED, -EOPNOTSUPP))
                        return 0; /* The DNSKEY is revoked or otherwise invalid, or we don't support the digest algorithm */
                if (r < 0)
                        return r;
                if (r > 0)
                        return 1;
        }

        return 0;
}

static int nsec3_hash_to_gcrypt_md(uint8_t algorithm) {

        /* Translates a DNSSEC NSEC3 hash algorithm into a gcrypt digest identifier */

        switch (algorithm) {

        case NSEC3_ALGORITHM_SHA1:
                return GCRY_MD_SHA1;

        default:
                return -EOPNOTSUPP;
        }
}

int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {
        uint8_t wire_format[DNS_WIRE_FOMAT_HOSTNAME_MAX];
        gcry_md_hd_t md = NULL;
        size_t hash_size;
        int algorithm;
        void *result;
        unsigned k;
        int r;

        assert(nsec3);
        assert(name);
        assert(ret);

        if (nsec3->key->type != DNS_TYPE_NSEC3)
                return -EINVAL;

        if (nsec3->nsec3.iterations > NSEC3_ITERATIONS_MAX) {
                log_debug("Ignoring NSEC3 RR %s with excessive number of iterations.", dns_resource_record_to_string(nsec3));
                return -EOPNOTSUPP;
        }

        algorithm = nsec3_hash_to_gcrypt_md(nsec3->nsec3.algorithm);
        if (algorithm < 0)
                return algorithm;

        initialize_libgcrypt();

        hash_size = gcry_md_get_algo_dlen(algorithm);
        assert(hash_size > 0);

        if (nsec3->nsec3.next_hashed_name_size != hash_size)
                return -EINVAL;

        r = dns_name_to_wire_format(name, wire_format, sizeof(wire_format), true);
        if (r < 0)
                return r;

        gcry_md_open(&md, algorithm, 0);
        if (!md)
                return -EIO;

        gcry_md_write(md, wire_format, r);
        gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);

        result = gcry_md_read(md, 0);
        if (!result) {
                r = -EIO;
                goto finish;
        }

        for (k = 0; k < nsec3->nsec3.iterations; k++) {
                uint8_t tmp[hash_size];
                memcpy(tmp, result, hash_size);

                gcry_md_reset(md);
                gcry_md_write(md, tmp, hash_size);
                gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);

                result = gcry_md_read(md, 0);
                if (!result) {
                        r = -EIO;
                        goto finish;
                }
        }

        memcpy(ret, result, hash_size);
        r = (int) hash_size;

finish:
        gcry_md_close(md);
        return r;
}

static int nsec3_is_good(DnsResourceRecord *rr, DnsResourceRecord *nsec3) {
        const char *a, *b;
        int r;

        assert(rr);

        if (rr->key->type != DNS_TYPE_NSEC3)
                return 0;

        /* RFC  5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */
        if (!IN_SET(rr->nsec3.flags, 0, 1))
                return 0;

        /* Ignore NSEC3 RRs whose algorithm we don't know */
        if (nsec3_hash_to_gcrypt_md(rr->nsec3.algorithm) < 0)
                return 0;
        /* Ignore NSEC3 RRs with an excessive number of required iterations */
        if (rr->nsec3.iterations > NSEC3_ITERATIONS_MAX)
                return 0;

        /* Ignore NSEC3 RRs generated from wildcards */
        if (rr->n_skip_labels_source != 0)
                return 0;
        /* Ignore NSEC3 RRs that are located anywhere else than one label below the zone */
        if (rr->n_skip_labels_signer != 1)
                return 0;

        if (!nsec3)
                return 1;

        /* If a second NSEC3 RR is specified, also check if they are from the same zone. */

        if (nsec3 == rr) /* Shortcut */
                return 1;

        if (rr->key->class != nsec3->key->class)
                return 0;
        if (rr->nsec3.algorithm != nsec3->nsec3.algorithm)
                return 0;
        if (rr->nsec3.iterations != nsec3->nsec3.iterations)
                return 0;
        if (rr->nsec3.salt_size != nsec3->nsec3.salt_size)
                return 0;
        if (memcmp(rr->nsec3.salt, nsec3->nsec3.salt, rr->nsec3.salt_size) != 0)
                return 0;

        a = DNS_RESOURCE_KEY_NAME(rr->key);
        r = dns_name_parent(&a); /* strip off hash */
        if (r < 0)
                return r;
        if (r == 0)
                return 0;

        b = DNS_RESOURCE_KEY_NAME(nsec3->key);
        r = dns_name_parent(&b); /* strip off hash */
        if (r < 0)
                return r;
        if (r == 0)
                return 0;

        /* Make sure both have the same parent */
        return dns_name_equal(a, b);
}

static int nsec3_hashed_domain_format(const uint8_t *hashed, size_t hashed_size, const char *zone, char **ret) {
        _cleanup_free_ char *l = NULL;
        char *j;

        assert(hashed);
        assert(hashed_size > 0);
        assert(zone);
        assert(ret);

        l = base32hexmem(hashed, hashed_size, false);
        if (!l)
                return -ENOMEM;

        j = strjoin(l, ".", zone, NULL);
        if (!j)
                return -ENOMEM;

        *ret = j;
        return (int) hashed_size;
}

static int nsec3_hashed_domain_make(DnsResourceRecord *nsec3, const char *domain, const char *zone, char **ret) {
        uint8_t hashed[DNSSEC_HASH_SIZE_MAX];
        int hashed_size;

        assert(nsec3);
        assert(domain);
        assert(zone);
        assert(ret);

        hashed_size = dnssec_nsec3_hash(nsec3, domain, hashed);
        if (hashed_size < 0)
                return hashed_size;

        return nsec3_hashed_domain_format(hashed, (size_t) hashed_size, zone, ret);
}

/* See RFC 5155, Section 8
 * First try to find a NSEC3 record that matches our query precisely, if that fails, find the closest
 * enclosure. Secondly, find a proof that there is no closer enclosure and either a proof that there
 * is no wildcard domain as a direct descendant of the closest enclosure, or find an NSEC3 record that
 * matches the wildcard domain.
 *
 * Based on this we can prove either the existence of the record in @key, or NXDOMAIN or NODATA, or
 * that there is no proof either way. The latter is the case if a the proof of non-existence of a given
 * name uses an NSEC3 record with the opt-out bit set. Lastly, if we are given insufficient NSEC3 records
 * to conclude anything we indicate this by returning NO_RR. */
static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
        _cleanup_free_ char *next_closer_domain = NULL, *wildcard_domain = NULL;
        const char *zone, *p, *pp = NULL, *wildcard;
        DnsResourceRecord *rr, *enclosure_rr, *zone_rr, *wildcard_rr = NULL;
        DnsAnswerFlags flags;
        int hashed_size, r;
        bool a, no_closer = false, no_wildcard = false, optout = false;

        assert(key);
        assert(result);

        /* First step, find the zone name and the NSEC3 parameters of the zone.
         * it is sufficient to look for the longest common suffix we find with
         * any NSEC3 RR in the response. Any NSEC3 record will do as all NSEC3
         * records from a given zone in a response must use the same
         * parameters. */
        zone = DNS_RESOURCE_KEY_NAME(key);
        for (;;) {
                DNS_ANSWER_FOREACH_FLAGS(zone_rr, flags, answer) {
                        r = nsec3_is_good(zone_rr, NULL);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                continue;

                        r = dns_name_equal_skip(DNS_RESOURCE_KEY_NAME(zone_rr->key), 1, zone);
                        if (r < 0)
                                return r;
                        if (r > 0)
                                goto found_zone;
                }

                /* Strip one label from the front */
                r = dns_name_parent(&zone);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;
        }

        *result = DNSSEC_NSEC_NO_RR;
        return 0;

found_zone:
        /* Second step, find the closest encloser NSEC3 RR in 'answer' that matches 'key' */
        p = DNS_RESOURCE_KEY_NAME(key);
        for (;;) {
                _cleanup_free_ char *hashed_domain = NULL;

                hashed_size = nsec3_hashed_domain_make(zone_rr, p, zone, &hashed_domain);
                if (hashed_size == -EOPNOTSUPP) {
                        *result = DNSSEC_NSEC_UNSUPPORTED_ALGORITHM;
                        return 0;
                }
                if (hashed_size < 0)
                        return hashed_size;

                DNS_ANSWER_FOREACH_FLAGS(enclosure_rr, flags, answer) {

                        r = nsec3_is_good(enclosure_rr, zone_rr);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                continue;

                        if (enclosure_rr->nsec3.next_hashed_name_size != (size_t) hashed_size)
                                continue;

                        r = dns_name_equal(DNS_RESOURCE_KEY_NAME(enclosure_rr->key), hashed_domain);
                        if (r < 0)
                                return r;
                        if (r > 0) {
                                a = flags & DNS_ANSWER_AUTHENTICATED;
                                goto found_closest_encloser;
                        }
                }

                /* We didn't find the closest encloser with this name,
                 * but let's remember this domain name, it might be
                 * the next closer name */

                pp = p;

                /* Strip one label from the front */
                r = dns_name_parent(&p);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;
        }

        *result = DNSSEC_NSEC_NO_RR;
        return 0;

found_closest_encloser:
        /* We found a closest encloser in 'p'; next closer is 'pp' */

        /* Ensure this is not a DNAME domain, see RFC5155, section 8.3. */
        if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_DNAME))
                return -EBADMSG;

        /* Ensure that this data is from the delegated domain
         * (i.e. originates from the "lower" DNS server), and isn't
         * just glue records (i.e. doesn't originate from the "upper"
         * DNS server). */
        if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_NS) &&
            !bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_SOA))
                return -EBADMSG;

        if (!pp) {
                /* No next closer NSEC3 RR. That means there's a direct NSEC3 RR for our key. */
                if (bitmap_isset(enclosure_rr->nsec3.types, key->type))
                        *result = DNSSEC_NSEC_FOUND;
                else if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_CNAME))
                        *result = DNSSEC_NSEC_CNAME;
                else
                        *result = DNSSEC_NSEC_NODATA;

                if (authenticated)
                        *authenticated = a;
                if (ttl)
                        *ttl = enclosure_rr->ttl;

                return 0;
        }

        /* Prove that there is no next closer and whether or not there is a wildcard domain. */

        wildcard = strjoina("*.", p);
        r = nsec3_hashed_domain_make(enclosure_rr, wildcard, zone, &wildcard_domain);
        if (r < 0)
                return r;
        if (r != hashed_size)
                return -EBADMSG;

        r = nsec3_hashed_domain_make(enclosure_rr, pp, zone, &next_closer_domain);
        if (r < 0)
                return r;
        if (r != hashed_size)
                return -EBADMSG;

        DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
                _cleanup_free_ char *next_hashed_domain = NULL;

                r = nsec3_is_good(rr, zone_rr);
                if (r < 0)
                        return r;
                if (r == 0)
                        continue;

                r = nsec3_hashed_domain_format(rr->nsec3.next_hashed_name, rr->nsec3.next_hashed_name_size, zone, &next_hashed_domain);
                if (r < 0)
                        return r;

                r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), next_closer_domain, next_hashed_domain);
                if (r < 0)
                        return r;
                if (r > 0) {
                        if (rr->nsec3.flags & 1)
                                optout = true;

                        a = a && (flags & DNS_ANSWER_AUTHENTICATED);

                        no_closer = true;
                }

                r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), wildcard_domain);
                if (r < 0)
                        return r;
                if (r > 0) {
                        a = a && (flags & DNS_ANSWER_AUTHENTICATED);

                        wildcard_rr = rr;
                }

                r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), wildcard_domain, next_hashed_domain);
                if (r < 0)
                        return r;
                if (r > 0) {
                        if (rr->nsec3.flags & 1)
                                /* This only makes sense if we have a wildcard delegation, which is
                                 * very unlikely, see RFC 4592, Section 4.2, but we cannot rely on
                                 * this not happening, so hence cannot simply conclude NXDOMAIN as
                                 * we would wish */
                                optout = true;

                        a = a && (flags & DNS_ANSWER_AUTHENTICATED);

                        no_wildcard = true;
                }
        }

        if (wildcard_rr && no_wildcard)
                return -EBADMSG;

        if (!no_closer) {
                *result = DNSSEC_NSEC_NO_RR;
                return 0;
        }

        if (wildcard_rr) {
                /* A wildcard exists that matches our query. */
                if (optout)
                        /* This is not specified in any RFC to the best of my knowledge, but
                         * if the next closer enclosure is covered by an opt-out NSEC3 RR
                         * it means that we cannot prove that the source of synthesis is
                         * correct, as there may be a closer match. */
                        *result = DNSSEC_NSEC_OPTOUT;
                else if (bitmap_isset(wildcard_rr->nsec3.types, key->type))
                        *result = DNSSEC_NSEC_FOUND;
                else if (bitmap_isset(wildcard_rr->nsec3.types, DNS_TYPE_CNAME))
                        *result = DNSSEC_NSEC_CNAME;
                else
                        *result = DNSSEC_NSEC_NODATA;
        } else {
                if (optout)
                        /* The RFC only specifies that we have to care for optout for NODATA for
                         * DS records. However, children of an insecure opt-out delegation should
                         * also be considered opt-out, rather than verified NXDOMAIN.
                         * Note that we do not require a proof of wildcard non-existence if the
                         * next closer domain is covered by an opt-out, as that would not provide
                         * any additional information. */
                        *result = DNSSEC_NSEC_OPTOUT;
                else if (no_wildcard)
                        *result = DNSSEC_NSEC_NXDOMAIN;
                else {
                        *result = DNSSEC_NSEC_NO_RR;

                        return 0;
                }
        }

        if (authenticated)
                *authenticated = a;

        if (ttl)
                *ttl = enclosure_rr->ttl;

        return 0;
}

int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
        DnsResourceRecord *rr;
        bool have_nsec3 = false;
        DnsAnswerFlags flags;
        int r;

        assert(key);
        assert(result);

        /* Look for any NSEC/NSEC3 RRs that say something about the specified key. */

        DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {

                if (rr->key->class != key->class)
                        continue;

                switch (rr->key->type) {

                case DNS_TYPE_NSEC:

                        r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), DNS_RESOURCE_KEY_NAME(key));
                        if (r < 0)
                                return r;
                        if (r > 0) {
                                if (key->type == DNS_TYPE_DS) {
                                        /* If we look for a DS RR and the server sent us the NSEC RR of the child zone
                                         * we have a problem. For DS RRs we want the NSEC RR from the parent */
                                        if (bitmap_isset(rr->nsec.types, DNS_TYPE_SOA))
                                                continue;
                                } else {
                                        /* For all RR types, ensure that if NS is set SOA is set too, so that we know
                                         * we got the child's NSEC. */
                                        if (bitmap_isset(rr->nsec.types, DNS_TYPE_NS) &&
                                            !bitmap_isset(rr->nsec.types, DNS_TYPE_SOA))
                                                continue;
                                }

                                if (bitmap_isset(rr->nsec.types, key->type))
                                        *result = DNSSEC_NSEC_FOUND;
                                else if (bitmap_isset(rr->nsec.types, DNS_TYPE_CNAME))
                                        *result = DNSSEC_NSEC_CNAME;
                                else
                                        *result = DNSSEC_NSEC_NODATA;

                                if (authenticated)
                                        *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
                                if (ttl)
                                        *ttl = rr->ttl;

                                return 0;
                        }

                        r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), DNS_RESOURCE_KEY_NAME(key), rr->nsec.next_domain_name);
                        if (r < 0)
                                return r;
                        if (r > 0) {
                                *result = DNSSEC_NSEC_NXDOMAIN;

                                if (authenticated)
                                        *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
                                if (ttl)
                                        *ttl = rr->ttl;

                                return 0;
                        }
                        break;

                case DNS_TYPE_NSEC3:
                        have_nsec3 = true;
                        break;
                }
        }

        /* OK, this was not sufficient. Let's see if NSEC3 can help. */
        if (have_nsec3)
                return dnssec_test_nsec3(answer, key, result, authenticated, ttl);

        /* No approproate NSEC RR found, report this. */
        *result = DNSSEC_NSEC_NO_RR;
        return 0;
}

int dnssec_nsec_test_enclosed(DnsAnswer *answer, uint16_t type, const char *name, const char *zone, bool *authenticated) {
        DnsResourceRecord *rr;
        DnsAnswerFlags flags;
        int r;

        assert(name);
        assert(zone);

        /* Checks whether there's an NSEC/NSEC3 that proves that the specified 'name' is non-existing in the specified
         * 'zone'. The 'zone' must be a suffix of the 'name'. */

        DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
                bool found = false;

                if (rr->key->type != type && type != DNS_TYPE_ANY)
                        continue;

                switch (rr->key->type) {

                case DNS_TYPE_NSEC:

                        /* We only care for NSEC RRs from the indicated zone */
                        r = dns_resource_record_is_signer(rr, zone);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                continue;

                        r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), name, rr->nsec.next_domain_name);
                        if (r < 0)
                                return r;

                        found = r > 0;
                        break;

                case DNS_TYPE_NSEC3: {
                        _cleanup_free_ char *hashed_domain = NULL, *next_hashed_domain = NULL;

                        /* We only care for NSEC3 RRs from the indicated zone */
                        r = dns_resource_record_is_signer(rr, zone);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                continue;

                        r = nsec3_is_good(rr, NULL);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                break;

                        /* Format the domain we are testing with the NSEC3 RR's hash function */
                        r = nsec3_hashed_domain_make(
                                        rr,
                                        name,
                                        zone,
                                        &hashed_domain);
                        if (r < 0)
                                return r;
                        if ((size_t) r != rr->nsec3.next_hashed_name_size)
                                break;

                        /* Format the NSEC3's next hashed name as proper domain name */
                        r = nsec3_hashed_domain_format(
                                        rr->nsec3.next_hashed_name,
                                        rr->nsec3.next_hashed_name_size,
                                        zone,
                                        &next_hashed_domain);
                        if (r < 0)
                                return r;

                        r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), hashed_domain, next_hashed_domain);
                        if (r < 0)
                                return r;

                        found = r > 0;
                        break;
                }

                default:
                        continue;
                }

                if (found) {
                        if (authenticated)
                                *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
                        return 1;
                }
        }

        return 0;
}

static int dnssec_test_positive_wildcard_nsec3(
                DnsAnswer *answer,
                const char *name,
                const char *source,
                const char *zone,
                bool *authenticated) {

        const char *next_closer = NULL;
        int r;

        /* Run a positive NSEC3 wildcard proof. Specifically:
         *
         * A proof that the the "next closer" of the generating wildcard does not exist.
         *
         * Note a key difference between the NSEC3 and NSEC versions of the proof. NSEC RRs don't have to exist for
         * empty non-transients. NSEC3 RRs however have to. This means it's sufficient to check if the next closer name
         * exists for the NSEC3 RR and we are done.
         *
         * To prove that a.b.c.d.e.f is rightfully synthesized from a wildcard *.d.e.f all we have to check is that
         * c.d.e.f does not exist. */

        for (;;) {
                next_closer = name;
                r = dns_name_parent(&name);
                if (r < 0)
                        return r;
                if (r == 0)
                        return 0;

                r = dns_name_equal(name, source);
                if (r < 0)
                        return r;
                if (r > 0)
                        break;
        }

        return dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC3, next_closer, zone, authenticated);
}

static int dnssec_test_positive_wildcard_nsec(
                DnsAnswer *answer,
                const char *name,
                const char *source,
                const char *zone,
                bool *_authenticated) {

        bool authenticated = true;
        int r;

        /* Run a positive NSEC wildcard proof. Specifically:
         *
         * A proof that there's neither a wildcard name nor a non-wildcard name that is a suffix of the name "name" and
         * a prefix of the synthesizing source "source" in the zone "zone".
         *
         * See RFC 5155, Section 8.8 and RFC 4035, Section 5.3.4
         *
         * Note that if we want to prove that a.b.c.d.e.f is rightfully synthesized from a wildcard *.d.e.f, then we
         * have to prove that none of the following exist:
         *
         *      1) a.b.c.d.e.f
         *      2) *.b.c.d.e.f
         *      3)   b.c.d.e.f
         *      4)   *.c.d.e.f
         *      5)     c.d.e.f
         *
         */

        for (;;) {
                _cleanup_free_ char *wc = NULL;
                bool a = false;

                /* Check if there's an NSEC or NSEC3 RR that proves that the mame we determined is really non-existing,
                 * i.e between the owner name and the next name of an NSEC RR. */
                r = dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC, name, zone, &a);
                if (r <= 0)
                        return r;

                authenticated = authenticated && a;

                /* Strip one label off */
                r = dns_name_parent(&name);
                if (r <= 0)
                        return r;

                /* Did we reach the source of synthesis? */
                r = dns_name_equal(name, source);
                if (r < 0)
                        return r;
                if (r > 0) {
                        /* Successful exit */
                        *_authenticated = authenticated;
                        return 1;
                }

                /* Safety check, that the source of synthesis is still our suffix */
                r = dns_name_endswith(name, source);
                if (r < 0)
                        return r;
                if (r == 0)
                        return -EBADMSG;

                /* Replace the label we stripped off with an asterisk */
                wc = strappend("*.", name);
                if (!wc)
                        return -ENOMEM;

                /* And check if the proof holds for the asterisk name, too */
                r = dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC, wc, zone, &a);
                if (r <= 0)
                        return r;

                authenticated = authenticated && a;
                /* In the next iteration we'll check the non-asterisk-prefixed version */
        }
}

int dnssec_test_positive_wildcard(
                DnsAnswer *answer,
                const char *name,
                const char *source,
                const char *zone,
                bool *authenticated) {

        int r;

        assert(name);
        assert(source);
        assert(zone);
        assert(authenticated);

        r = dns_answer_contains_zone_nsec3(answer, zone);
        if (r < 0)
                return r;
        if (r > 0)
                return dnssec_test_positive_wildcard_nsec3(answer, name, source, zone, authenticated);
        else
                return dnssec_test_positive_wildcard_nsec(answer, name, source, zone, authenticated);
}

static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = {
        [DNSSEC_VALIDATED] = "validated",
        [DNSSEC_VALIDATED_WILDCARD] = "validated-wildcard",
        [DNSSEC_INVALID] = "invalid",
        [DNSSEC_SIGNATURE_EXPIRED] = "signature-expired",
        [DNSSEC_UNSUPPORTED_ALGORITHM] = "unsupported-algorithm",
        [DNSSEC_NO_SIGNATURE] = "no-signature",
        [DNSSEC_MISSING_KEY] = "missing-key",
        [DNSSEC_UNSIGNED] = "unsigned",
        [DNSSEC_FAILED_AUXILIARY] = "failed-auxiliary",
        [DNSSEC_NSEC_MISMATCH] = "nsec-mismatch",
        [DNSSEC_INCOMPATIBLE_SERVER] = "incompatible-server",
};
DEFINE_STRING_TABLE_LOOKUP(dnssec_result, DnssecResult);