1 /* $NetBSD: dns.h,v 1.5 2022/10/08 16:12:45 christos Exp $ */ 2 3 #ifndef _DNS_H_INCLUDED_ 4 #define _DNS_H_INCLUDED_ 5 6 /*++ 7 /* NAME 8 /* dns 3h 9 /* SUMMARY 10 /* domain name service lookup 11 /* SYNOPSIS 12 /* #include <dns.h> 13 /* DESCRIPTION 14 /* .nf 15 16 /* 17 * System library. 18 */ 19 #include <netinet/in.h> 20 #include <arpa/nameser.h> 21 #ifdef RESOLVE_H_NEEDS_STDIO_H 22 #include <stdio.h> 23 #endif 24 #ifdef RESOLVE_H_NEEDS_NAMESER8_COMPAT_H 25 #include <nameser8_compat.h> 26 #endif 27 #ifdef RESOLVE_H_NEEDS_ARPA_NAMESER_COMPAT_H 28 #include <arpa/nameser_compat.h> 29 #endif 30 #include <resolv.h> 31 32 /* 33 * Name server compatibility. These undocumented macros appear in the file 34 * <arpa/nameser.h>, but since they are undocumented we should not count on 35 * their presence, and so they are included here just in case. 36 */ 37 #ifndef GETSHORT 38 39 #define GETSHORT(s, cp) { \ 40 unsigned char *t_cp = (u_char *)(cp); \ 41 (s) = ((unsigned)t_cp[0] << 8) \ 42 | ((unsigned)t_cp[1]) \ 43 ; \ 44 (cp) += 2; \ 45 } 46 47 #define GETLONG(l, cp) { \ 48 unsigned char *t_cp = (u_char *)(cp); \ 49 (l) = ((unsigned)t_cp[0] << 24) \ 50 | ((unsigned)t_cp[1] << 16) \ 51 | ((unsigned)t_cp[2] << 8) \ 52 | ((unsigned)t_cp[3]) \ 53 ; \ 54 (cp) += 4; \ 55 } 56 57 #endif 58 59 /* 60 * Provide API compatibility for systems without res_nxxx() API. Also 61 * require calling dns_get_h_errno() instead of directly accessing the 62 * global h_errno variable. We should not count on that being updated. 63 */ 64 #if !defined(NO_RES_NCALLS) && defined(__RES) && (__RES >= 19991006) 65 #define USE_RES_NCALLS 66 #undef h_errno 67 #define h_errno use_dns_get_h_errno_instead_of_h_errno 68 #endif 69 70 /* 71 * Disable DNSSEC at compile-time even if RES_USE_DNSSEC is available 72 */ 73 #ifdef NO_DNSSEC 74 #undef RES_USE_DNSSEC 75 #undef RES_TRUSTAD 76 #endif 77 78 /* 79 * Compatibility with systems that lack RES_USE_DNSSEC and RES_USE_EDNS0 80 */ 81 #ifndef RES_USE_DNSSEC 82 #define RES_USE_DNSSEC 0 83 #endif 84 #ifndef RES_USE_EDNS0 85 #define RES_USE_EDNS0 0 86 #endif 87 #ifndef RES_TRUSTAD 88 #define RES_TRUSTAD 0 89 #endif 90 91 /*- 92 * TLSA: https://tools.ietf.org/html/rfc6698#section-7.1 93 * RRSIG: http://tools.ietf.org/html/rfc4034#section-3 94 * 95 * We don't request RRSIG, but we get it "for free" when we send the DO-bit. 96 */ 97 #ifndef T_TLSA 98 #define T_TLSA 52 99 #endif 100 #ifndef T_RRSIG 101 #define T_RRSIG 46 /* Avoid unknown RR in logs */ 102 #endif 103 #ifndef T_DNAME 104 #define T_DNAME 39 /* [RFC6672] */ 105 #endif 106 107 /* 108 * https://tools.ietf.org/html/rfc6698#section-7.2 109 */ 110 #define DNS_TLSA_USAGE_CA_CONSTRAINT 0 111 #define DNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT 1 112 #define DNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION 2 113 #define DNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE 3 114 115 /* 116 * https://tools.ietf.org/html/rfc6698#section-7.3 117 */ 118 #define DNS_TLSA_SELECTOR_FULL_CERTIFICATE 0 119 #define DNS_TLSA_SELECTOR_SUBJECTPUBLICKEYINFO 1 120 121 /* 122 * https://tools.ietf.org/html/rfc6698#section-7.4 123 */ 124 #define DNS_TLSA_MATCHING_TYPE_NO_HASH_USED 0 125 #define DNS_TLSA_MATCHING_TYPE_SHA256 1 126 #define DNS_TLSA_MATCHING_TYPE_SHA512 2 127 128 /* 129 * SunOS 4 needs this. 130 */ 131 #ifndef T_TXT 132 #define T_TXT 16 133 #endif 134 135 /* 136 * Utility library. 137 */ 138 #include <vstring.h> 139 #include <sock_addr.h> 140 #include <myaddrinfo.h> 141 142 /* 143 * Structure for fixed resource record data. 144 */ 145 typedef struct DNS_FIXED { 146 unsigned short type; /* T_A, T_CNAME, etc. */ 147 unsigned short class; /* C_IN, etc. */ 148 unsigned int ttl; /* always */ 149 unsigned length; /* record length */ 150 } DNS_FIXED; 151 152 /* 153 * Structure of a DNS resource record after expansion. The components are 154 * named after the things one can expect to find in a DNS resource record. 155 */ 156 typedef struct DNS_RR { 157 char *qname; /* query name, mystrdup()ed */ 158 char *rname; /* reply name, mystrdup()ed */ 159 unsigned short type; /* T_A, T_CNAME, etc. */ 160 unsigned short class; /* C_IN, etc. */ 161 unsigned int ttl; /* always */ 162 unsigned int dnssec_valid; /* DNSSEC validated */ 163 unsigned short pref; /* T_MX only */ 164 struct DNS_RR *next; /* linkage */ 165 size_t data_len; /* actual data size */ 166 char data[1]; /* actually a bunch of data */ 167 } DNS_RR; 168 169 /* 170 * dns_strerror.c 171 */ 172 extern const char *dns_strerror(unsigned); 173 174 /* 175 * dns_strtype.c 176 */ 177 extern const char *dns_strtype(unsigned); 178 extern unsigned dns_type(const char *); 179 180 /* 181 * dns_strrecord.c 182 */ 183 extern char *dns_strrecord(VSTRING *, DNS_RR *); 184 185 /* 186 * dns_rr.c 187 */ 188 extern DNS_RR *dns_rr_create(const char *, const char *, 189 ushort, ushort, 190 unsigned, unsigned, 191 const char *, size_t); 192 extern void dns_rr_free(DNS_RR *); 193 extern DNS_RR *dns_rr_copy(DNS_RR *); 194 extern DNS_RR *dns_rr_append(DNS_RR *, DNS_RR *); 195 extern DNS_RR *dns_rr_sort(DNS_RR *, int (*) (DNS_RR *, DNS_RR *)); 196 extern int dns_rr_compare_pref_ipv6(DNS_RR *, DNS_RR *); 197 extern int dns_rr_compare_pref_ipv4(DNS_RR *, DNS_RR *); 198 extern int dns_rr_compare_pref_any(DNS_RR *, DNS_RR *); 199 extern int dns_rr_compare_pref(DNS_RR *, DNS_RR *); 200 extern DNS_RR *dns_rr_shuffle(DNS_RR *); 201 extern DNS_RR *dns_rr_remove(DNS_RR *, DNS_RR *); 202 203 /* 204 * dns_rr_to_pa.c 205 */ 206 extern const char *dns_rr_to_pa(DNS_RR *, MAI_HOSTADDR_STR *); 207 208 /* 209 * dns_sa_to_rr.c 210 */ 211 extern DNS_RR *dns_sa_to_rr(const char *, unsigned, struct sockaddr *); 212 213 /* 214 * dns_rr_to_sa.c 215 */ 216 extern int dns_rr_to_sa(DNS_RR *, unsigned, struct sockaddr *, SOCKADDR_SIZE *); 217 218 /* 219 * dns_rr_eq_sa.c 220 */ 221 extern int dns_rr_eq_sa(DNS_RR *, struct sockaddr *); 222 223 #ifdef HAS_IPV6 224 #define DNS_RR_EQ_SA(rr, sa) \ 225 ((SOCK_ADDR_IN_FAMILY(sa) == AF_INET && (rr)->type == T_A \ 226 && SOCK_ADDR_IN_ADDR(sa).s_addr == IN_ADDR((rr)->data).s_addr) \ 227 || (SOCK_ADDR_IN_FAMILY(sa) == AF_INET6 && (rr)->type == T_AAAA \ 228 && memcmp((char *) &(SOCK_ADDR_IN6_ADDR(sa)), \ 229 (rr)->data, (rr)->data_len) == 0)) 230 #else 231 #define DNS_RR_EQ_SA(rr, sa) \ 232 (SOCK_ADDR_IN_FAMILY(sa) == AF_INET && (rr)->type == T_A \ 233 && SOCK_ADDR_IN_ADDR(sa).s_addr == IN_ADDR((rr)->data).s_addr) 234 #endif 235 236 /* 237 * dns_lookup.c 238 */ 239 extern int dns_lookup_x(const char *, unsigned, unsigned, DNS_RR **, 240 VSTRING *, VSTRING *, int *, unsigned); 241 extern int dns_lookup_rl(const char *, unsigned, DNS_RR **, VSTRING *, 242 VSTRING *, int *, int,...); 243 extern int dns_lookup_rv(const char *, unsigned, DNS_RR **, VSTRING *, 244 VSTRING *, int *, int, unsigned *); 245 extern int dns_get_h_errno(void); 246 247 #define dns_lookup(name, type, rflags, list, fqdn, why) \ 248 dns_lookup_x((name), (type), (rflags), (list), (fqdn), (why), (int *) 0, \ 249 (unsigned) 0) 250 #define dns_lookup_r(name, type, rflags, list, fqdn, why, rcode) \ 251 dns_lookup_x((name), (type), (rflags), (list), (fqdn), (why), (rcode), \ 252 (unsigned) 0) 253 #define dns_lookup_l(name, rflags, list, fqdn, why, lflags, ...) \ 254 dns_lookup_rl((name), (rflags), (list), (fqdn), (why), (int *) 0, \ 255 (lflags), __VA_ARGS__) 256 #define dns_lookup_v(name, rflags, list, fqdn, why, lflags, ltype) \ 257 dns_lookup_rv((name), (rflags), (list), (fqdn), (why), (int *) 0, \ 258 (lflags), (ltype)) 259 260 /* 261 * The dns_lookup() rflag that requests DNSSEC validation. 262 */ 263 #define DNS_WANT_DNSSEC_VALIDATION(rflags) ((rflags) & RES_USE_DNSSEC) 264 265 /* 266 * lflags. 267 */ 268 #define DNS_REQ_FLAG_STOP_OK (1<<0) 269 #define DNS_REQ_FLAG_STOP_INVAL (1<<1) 270 #define DNS_REQ_FLAG_STOP_NULLMX (1<<2) 271 #define DNS_REQ_FLAG_STOP_MX_POLICY (1<<3) 272 #define DNS_REQ_FLAG_NCACHE_TTL (1<<4) 273 #define DNS_REQ_FLAG_NONE (0) 274 275 /* 276 * Status codes. Failures must have negative codes so they will not collide 277 * with valid counts of answer records etc. 278 * 279 * When a function queries multiple record types for one name, it issues one 280 * query for each query record type. Each query returns a (status, rcode, 281 * text). Only one of these (status, rcode, text) will be returned to the 282 * caller. The selection is based on the status code precedence. 283 * 284 * - Return DNS_OK (and the corresponding rcode) as long as any query returned 285 * DNS_OK. If this is changed, then code needs to be added to prevent memory 286 * leaks. 287 * 288 * - Return DNS_RETRY (and the corresponding rcode and text) instead of any 289 * hard negative result. 290 * 291 * - Return DNS_NOTFOUND (and the corresponding rcode and text) only when all 292 * queries returned DNS_NOTFOUND. 293 * 294 * DNS_POLICY ranks higher than DNS_RETRY because there was a DNS_OK result, 295 * but the reply filter dropped it. This is a very soft error. 296 * 297 * Below is the precedence order. The order between DNS_RETRY and DNS_NOTFOUND 298 * is arbitrary. 299 */ 300 #define DNS_RECURSE (-7) /* internal only: recursion needed */ 301 #define DNS_NOTFOUND (-6) /* query ok, data not found */ 302 #define DNS_NULLMX (-5) /* query ok, service unavailable */ 303 #define DNS_FAIL (-4) /* query failed, don't retry */ 304 #define DNS_INVAL (-3) /* query ok, malformed reply */ 305 #define DNS_RETRY (-2) /* query failed, try again */ 306 #define DNS_POLICY (-1) /* query ok, all records dropped */ 307 #define DNS_OK 0 /* query succeeded */ 308 309 /* 310 * How long can a DNS name or single text value be? 311 */ 312 #define DNS_NAME_LEN 1024 313 314 /* 315 * dns_rr_filter.c. 316 */ 317 extern void dns_rr_filter_compile(const char *, const char *); 318 319 #ifdef LIBDNS_INTERNAL 320 #include <maps.h> 321 extern MAPS *dns_rr_filter_maps; 322 extern int dns_rr_filter_execute(DNS_RR **); 323 324 #endif 325 326 /* 327 * dns_str_resflags.c 328 */ 329 const char *dns_str_resflags(unsigned long); 330 331 /* 332 * dns_sec.c. 333 */ 334 #define DNS_SEC_FLAG_AVAILABLE (1<<0) /* got some DNSSEC validated reply */ 335 #define DNS_SEC_FLAG_DONT_PROBE (1<<1) /* probe already sent, or disabled */ 336 337 #define DNS_SEC_STATS_SET(flags) (dns_sec_stats |= (flags)) 338 #define DNS_SEC_STATS_TEST(flags) (dns_sec_stats & (flags)) 339 340 extern int dns_sec_stats; /* See DNS_SEC_FLAG_XXX above */ 341 extern void dns_sec_probe(int); 342 343 /* LICENSE 344 /* .ad 345 /* .fi 346 /* The Secure Mailer license must be distributed with this software. 347 /* AUTHOR(S) 348 /* Wietse Venema 349 /* IBM T.J. Watson Research 350 /* P.O. Box 704 351 /* Yorktown Heights, NY 10598, USA 352 /* 353 /* Wietse Venema 354 /* Google, Inc. 355 /* 111 8th Avenue 356 /* New York, NY 10011, USA 357 /*--*/ 358 359 #endif 360