1/*++ 2/* NAME 3/* dns_rr 3 4/* SUMMARY 5/* resource record memory and list management 6/* SYNOPSIS 7/* #include <dns.h> 8/* 9/* DNS_RR *dns_rr_create(qname, rname, type, class, ttl, preference, 10/* data, data_len) 11/* const char *qname; 12/* const char *rname; 13/* unsigned short type; 14/* unsigned short class; 15/* unsigned int ttl; 16/* unsigned preference; 17/* const char *data; 18/* size_t data_len; 19/* 20/* void dns_rr_free(list) 21/* DNS_RR *list; 22/* 23/* DNS_RR *dns_rr_copy(record) 24/* DNS_RR *record; 25/* 26/* DNS_RR *dns_rr_append(list, record) 27/* DNS_RR *list; 28/* DNS_RR *record; 29/* 30/* DNS_RR *dns_rr_sort(list, compar) 31/* DNS_RR *list 32/* int (*compar)(DNS_RR *, DNS_RR *); 33/* 34/* int dns_rr_compare_pref_ipv6(DNS_RR *a, DNS_RR *b) 35/* DNS_RR *list 36/* DNS_RR *list 37/* 38/* int dns_rr_compare_pref_ipv4(DNS_RR *a, DNS_RR *b) 39/* DNS_RR *list 40/* DNS_RR *list 41/* 42/* int dns_rr_compare_pref_any(DNS_RR *a, DNS_RR *b) 43/* DNS_RR *list 44/* DNS_RR *list 45/* 46/* DNS_RR *dns_rr_shuffle(list) 47/* DNS_RR *list; 48/* 49/* DNS_RR *dns_rr_remove(list, record) 50/* DNS_RR *list; 51/* DNS_RR *record; 52/* DESCRIPTION 53/* The routines in this module maintain memory for DNS resource record 54/* information, and maintain lists of DNS resource records. 55/* 56/* dns_rr_create() creates and initializes one resource record. 57/* The \fIqname\fR field specifies the query name. 58/* The \fIrname\fR field specifies the reply name. 59/* \fIpreference\fR is used for MX records; \fIdata\fR is a null 60/* pointer or specifies optional resource-specific data; 61/* \fIdata_len\fR is the amount of resource-specific data. 62/* 63/* dns_rr_free() releases the resource used by of zero or more 64/* resource records. 65/* 66/* dns_rr_copy() makes a copy of a resource record. 67/* 68/* dns_rr_append() appends a resource record to a (list of) resource 69/* record(s). 70/* A null input list is explicitly allowed. 71/* 72/* dns_rr_sort() sorts a list of resource records into ascending 73/* order according to a user-specified criterion. The result is the 74/* sorted list. 75/* 76/* dns_rr_compare_pref_XXX() are dns_rr_sort() helpers to sort 77/* records by their MX preference and by their address family. 78/* 79/* dns_rr_shuffle() randomly permutes a list of resource records. 80/* 81/* dns_rr_remove() removes the specified record from the specified list. 82/* The updated list is the result value. 83/* The record MUST be a list member. 84/* LICENSE 85/* .ad 86/* .fi 87/* The Secure Mailer license must be distributed with this software. 88/* AUTHOR(S) 89/* Wietse Venema 90/* IBM T.J. Watson Research 91/* P.O. Box 704 92/* Yorktown Heights, NY 10598, USA 93/*--*/ 94 95/* System library. */ 96 97#include <sys_defs.h> 98#include <string.h> 99#include <stdlib.h> 100 101/* Utility library. */ 102 103#include <msg.h> 104#include <mymalloc.h> 105#include <myrand.h> 106 107/* DNS library. */ 108 109#include "dns.h" 110 111/* dns_rr_create - fill in resource record structure */ 112 113DNS_RR *dns_rr_create(const char *qname, const char *rname, 114 ushort type, ushort class, 115 unsigned int ttl, unsigned pref, 116 const char *data, size_t data_len) 117{ 118 DNS_RR *rr; 119 120 rr = (DNS_RR *) mymalloc(sizeof(*rr) + data_len - 1); 121 rr->qname = mystrdup(qname); 122 rr->rname = mystrdup(rname); 123 rr->type = type; 124 rr->class = class; 125 rr->ttl = ttl; 126 rr->pref = pref; 127 if (data && data_len > 0) 128 memcpy(rr->data, data, data_len); 129 rr->data_len = data_len; 130 rr->next = 0; 131 return (rr); 132} 133 134/* dns_rr_free - destroy resource record structure */ 135 136void dns_rr_free(DNS_RR *rr) 137{ 138 if (rr) { 139 if (rr->next) 140 dns_rr_free(rr->next); 141 myfree(rr->qname); 142 myfree(rr->rname); 143 myfree((char *) rr); 144 } 145} 146 147/* dns_rr_copy - copy resource record */ 148 149DNS_RR *dns_rr_copy(DNS_RR *src) 150{ 151 ssize_t len = sizeof(*src) + src->data_len - 1; 152 DNS_RR *dst; 153 154 /* 155 * Combine struct assignment and data copy in one block copy operation. 156 */ 157 dst = (DNS_RR *) mymalloc(len); 158 memcpy((char *) dst, (char *) src, len); 159 dst->qname = mystrdup(src->qname); 160 dst->rname = mystrdup(src->rname); 161 dst->next = 0; 162 return (dst); 163} 164 165/* dns_rr_append - append resource record to list */ 166 167DNS_RR *dns_rr_append(DNS_RR *list, DNS_RR *rr) 168{ 169 if (list == 0) { 170 list = rr; 171 } else { 172 list->next = dns_rr_append(list->next, rr); 173 } 174 return (list); 175} 176 177/* dns_rr_compare_pref_ipv6 - compare records by preference, ipv6 preferred */ 178 179int dns_rr_compare_pref_ipv6(DNS_RR *a, DNS_RR *b) 180{ 181 if (a->pref != b->pref) 182 return (a->pref - b->pref); 183#ifdef HAS_IPV6 184 if (a->type == b->type) /* 200412 */ 185 return 0; 186 if (a->type == T_AAAA) 187 return (-1); 188 if (b->type == T_AAAA) 189 return (+1); 190#endif 191 return 0; 192} 193 194/* dns_rr_compare_pref_ipv4 - compare records by preference, ipv4 preferred */ 195 196int dns_rr_compare_pref_ipv4(DNS_RR *a, DNS_RR *b) 197{ 198 if (a->pref != b->pref) 199 return (a->pref - b->pref); 200#ifdef HAS_IPV6 201 if (a->type == b->type) 202 return 0; 203 if (a->type == T_AAAA) 204 return (+1); 205 if (b->type == T_AAAA) 206 return (-1); 207#endif 208 return 0; 209} 210 211/* dns_rr_compare_pref_any - compare records by preference, protocol-neutral */ 212 213int dns_rr_compare_pref_any(DNS_RR *a, DNS_RR *b) 214{ 215 if (a->pref != b->pref) 216 return (a->pref - b->pref); 217 return 0; 218} 219 220/* dns_rr_compare_pref - binary compatibility helper after name change */ 221 222int dns_rr_compare_pref(DNS_RR *a, DNS_RR *b) 223{ 224 return (dns_rr_compare_pref_ipv6(a, b)); 225} 226 227/* dns_rr_sort_callback - glue function */ 228 229static int (*dns_rr_sort_user) (DNS_RR *, DNS_RR *); 230 231static int dns_rr_sort_callback(const void *a, const void *b) 232{ 233 DNS_RR *aa = *(DNS_RR **) a; 234 DNS_RR *bb = *(DNS_RR **) b; 235 236 return (dns_rr_sort_user(aa, bb)); 237} 238 239/* dns_rr_sort - sort resource record list */ 240 241DNS_RR *dns_rr_sort(DNS_RR *list, int (*compar) (DNS_RR *, DNS_RR *)) 242{ 243 int (*saved_user) (DNS_RR *, DNS_RR *); 244 DNS_RR **rr_array; 245 DNS_RR *rr; 246 int len; 247 int i; 248 249 /* 250 * Save state and initialize. 251 */ 252 saved_user = dns_rr_sort_user; 253 dns_rr_sort_user = compar; 254 255 /* 256 * Build linear array with pointers to each list element. 257 */ 258 for (len = 0, rr = list; rr != 0; len++, rr = rr->next) 259 /* void */ ; 260 rr_array = (DNS_RR **) mymalloc(len * sizeof(*rr_array)); 261 for (len = 0, rr = list; rr != 0; len++, rr = rr->next) 262 rr_array[len] = rr; 263 264 /* 265 * Sort by user-specified criterion. 266 */ 267 qsort((char *) rr_array, len, sizeof(*rr_array), dns_rr_sort_callback); 268 269 /* 270 * Fix the links. 271 */ 272 for (i = 0; i < len - 1; i++) 273 rr_array[i]->next = rr_array[i + 1]; 274 rr_array[i]->next = 0; 275 list = rr_array[0]; 276 277 /* 278 * Cleanup. 279 */ 280 myfree((char *) rr_array); 281 dns_rr_sort_user = saved_user; 282 return (list); 283} 284 285/* dns_rr_shuffle - shuffle resource record list */ 286 287DNS_RR *dns_rr_shuffle(DNS_RR *list) 288{ 289 DNS_RR **rr_array; 290 DNS_RR *rr; 291 int len; 292 int i; 293 int r; 294 295 /* 296 * Build linear array with pointers to each list element. 297 */ 298 for (len = 0, rr = list; rr != 0; len++, rr = rr->next) 299 /* void */ ; 300 rr_array = (DNS_RR **) mymalloc(len * sizeof(*rr_array)); 301 for (len = 0, rr = list; rr != 0; len++, rr = rr->next) 302 rr_array[len] = rr; 303 304 /* 305 * Shuffle resource records. 306 */ 307 for (i = 0; i < len; i++) { 308 r = myrand() % len; 309 rr = rr_array[i]; 310 rr_array[i] = rr_array[r]; 311 rr_array[r] = rr; 312 } 313 314 /* 315 * Fix the links. 316 */ 317 for (i = 0; i < len - 1; i++) 318 rr_array[i]->next = rr_array[i + 1]; 319 rr_array[i]->next = 0; 320 list = rr_array[0]; 321 322 /* 323 * Cleanup. 324 */ 325 myfree((char *) rr_array); 326 return (list); 327} 328 329/* dns_rr_remove - remove record from list, return new list */ 330 331DNS_RR *dns_rr_remove(DNS_RR *list, DNS_RR *record) 332{ 333 if (list == 0) 334 msg_panic("dns_rr_remove: record not found"); 335 336 if (list == record) { 337 list = record->next; 338 record->next = 0; 339 dns_rr_free(record); 340 } else { 341 list->next = dns_rr_remove(list->next, record); 342 } 343 return (list); 344} 345