contrib/bind-9.2.4rc7/lib/bind/irs/hesiod.c

   1 #if defined(LIBC_SCCS) && !defined(lint)
   2 static const char rcsid[] = "$Id: hesiod.c,v 1.1.2.4 2004/05/17 07:46:43 marka Exp $";
   3 #endif
   4
   5 /*
   6  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   7  * Copyright (c) 1996,1999 by Internet Software Consortium.
   8  *
   9  * Permission to use, copy, modify, and distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  19  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  */
  21
  22 /*
  23  * This file is primarily maintained by <tytso@mit.edu> and <ghudson@mit.edu>.
  24  */
  25
  26 /*
  27  * hesiod.c --- the core portion of the hesiod resolver.
  28  *
  29  * This file is derived from the hesiod library from Project Athena;
  30  * It has been extensively rewritten by Theodore Ts'o to have a more
  31  * thread-safe interface.
  32  */
  33
  34 /* Imports */
  35
  36 #include "port_before.h"
  37
  38 #include <sys/types.h>
  39 #include <netinet/in.h>
  40 #include <arpa/nameser.h>
  41
  42 #include <errno.h>
  43 #include <netdb.h>
  44 #include <resolv.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include "port_after.h"
  50
  51 #include "pathnames.h"
  52 #include "hesiod.h"
  53 #include "hesiod_p.h"
  54
  55 /* Forward */
  56
  57 int             hesiod_init(void **context);
  58 void            hesiod_end(void *context);
  59 char *          hesiod_to_bind(void *context, const char *name,
  60                                const char *type);
  61 char **         hesiod_resolve(void *context, const char *name,
  62                                const char *type);
  63 void            hesiod_free_list(void *context, char **list);
  64
  65 static int      parse_config_file(struct hesiod_p *ctx, const char *filename);
  66 static char **  get_txt_records(struct hesiod_p *ctx, int class,
  67                                 const char *name);
  68 static int      init(struct hesiod_p *ctx);
  69
  70 /* Public */
  71
  72 /*
  73  * This function is called to initialize a hesiod_p.
  74  */
  75 int
  76 hesiod_init(void **context) {
  77         struct hesiod_p *ctx;
  78         char *cp;
  79
  80         ctx = malloc(sizeof(struct hesiod_p));
  81         if (ctx == 0) {
  82                 errno = ENOMEM;
  83                 return (-1);
  84         }
  85
  86         ctx->LHS = NULL;
  87         ctx->RHS = NULL;
  88         ctx->res = NULL;
  89
  90         if (parse_config_file(ctx, _PATH_HESIOD_CONF) < 0) {
  91 #ifdef DEF_RHS
  92                 /*
  93                  * Use compiled in defaults.
  94                  */
  95                 ctx->LHS = malloc(strlen(DEF_LHS) + 1);
  96                 ctx->RHS = malloc(strlen(DEF_RHS) + 1);
  97                 if (ctx->LHS == NULL || ctx->RHS == NULL) {
  98                         errno = ENOMEM;
  99                         goto cleanup;
 100                 }
 101                 strcpy(ctx->LHS, DEF_LHS);      /* (checked) */
 102                 strcpy(ctx->RHS, DEF_RHS);      /* (checked) */
 103 #else
 104                 goto cleanup;
 105 #endif
 106         }
 107         /*
 108          * The default RHS can be overridden by an environment
 109          * variable.
 110          */
 111         if ((cp = getenv("HES_DOMAIN")) != NULL) {
 112                 size_t RHSlen = strlen(cp) + 2;
 113                 if (ctx->RHS)
 114                         free(ctx->RHS);
 115                 ctx->RHS = malloc(RHSlen);
 116                 if (!ctx->RHS) {
 117                         errno = ENOMEM;
 118                         goto cleanup;
 119                 }
 120                 if (cp[0] == '.') {
 121                         strcpy(ctx->RHS, cp);   /* (checked) */
 122                 } else {
 123                         strcpy(ctx->RHS, ".");  /* (checked) */
 124                         strcat(ctx->RHS, cp);   /* (checked) */
 125                 }
 126         }
 127
 128         /*
 129          * If there is no default hesiod realm set, we return an
 130          * error.
 131          */
 132         if (!ctx->RHS) {
 133                 errno = ENOEXEC;
 134                 goto cleanup;
 135         }
 136
 137 #if 0
 138         if (res_ninit(ctx->res) < 0)
 139                 goto cleanup;
 140 #endif
 141
 142         *context = ctx;
 143         return (0);
 144
 145  cleanup:
 146         hesiod_end(ctx);
 147         return (-1);
 148 }
 149
 150 /*
 151  * This function deallocates the hesiod_p
 152  */
 153 void
 154 hesiod_end(void *context) {
 155         struct hesiod_p *ctx = (struct hesiod_p *) context;
 156         int save_errno = errno;
 157
 158         if (ctx->res)
 159                 res_nclose(ctx->res);
 160         if (ctx->RHS)
 161                 free(ctx->RHS);
 162         if (ctx->LHS)
 163                 free(ctx->LHS);
 164         if (ctx->res && ctx->free_res)
 165                 (*ctx->free_res)(ctx->res);
 166         free(ctx);
 167         errno = save_errno;
 168 }
 169
 170 /*
 171  * This function takes a hesiod (name, type) and returns a DNS
 172  * name which is to be resolved.
 173  */
 174 char *
 175 hesiod_to_bind(void *context, const char *name, const char *type) {
 176         struct hesiod_p *ctx = (struct hesiod_p *) context;
 177         char *bindname;
 178         char **rhs_list = NULL;
 179         const char *RHS, *cp;
 180
 181         /* Decide what our RHS is, and set cp to the end of the actual name. */
 182         if ((cp = strchr(name, '@')) != NULL) {
 183                 if (strchr(cp + 1, '.'))
 184                         RHS = cp + 1;
 185                 else if ((rhs_list = hesiod_resolve(context, cp + 1,
 186                     "rhs-extension")) != NULL)
 187                         RHS = *rhs_list;
 188                 else {
 189                         errno = ENOENT;
 190                         return (NULL);
 191                 }
 192         } else {
 193                 RHS = ctx->RHS;
 194                 cp = name + strlen(name);
 195         }
 196
 197         /*
 198          * Allocate the space we need, including up to three periods and
 199          * the terminating NUL.
 200          */
 201         if ((bindname = malloc((cp - name) + strlen(type) + strlen(RHS) +
 202             (ctx->LHS ? strlen(ctx->LHS) : 0) + 4)) == NULL) {
 203                 errno = ENOMEM;
 204                 if (rhs_list)
 205                         hesiod_free_list(context, rhs_list);
 206                 return NULL;
 207         }
 208
 209         /* Now put together the DNS name. */
 210         memcpy(bindname, name, cp - name);
 211         bindname[cp - name] = '\0';
 212         strcat(bindname, ".");
 213         strcat(bindname, type);
 214         if (ctx->LHS) {
 215                 if (ctx->LHS[0] != '.')
 216                         strcat(bindname, ".");
 217                 strcat(bindname, ctx->LHS);
 218         }
 219         if (RHS[0] != '.')
 220                 strcat(bindname, ".");
 221         strcat(bindname, RHS);
 222
 223         if (rhs_list)
 224                 hesiod_free_list(context, rhs_list);
 225
 226         return (bindname);
 227 }
 228
 229 /*
 230  * This is the core function.  Given a hesiod (name, type), it
 231  * returns an array of strings returned by the resolver.
 232  */
 233 char **
 234 hesiod_resolve(void *context, const char *name, const char *type) {
 235         struct hesiod_p *ctx = (struct hesiod_p *) context;
 236         char *bindname = hesiod_to_bind(context, name, type);
 237         char **retvec;
 238
 239         if (bindname == NULL)
 240                 return (NULL);
 241         if (init(ctx) == -1) {
 242                 free(bindname);
 243                 return (NULL);
 244         }
 245
 246         if ((retvec = get_txt_records(ctx, C_IN, bindname))) {
 247                 free(bindname);
 248                 return (retvec);
 249         }
 250
 251         if (errno != ENOENT)
 252                 return (NULL);
 253
 254         retvec = get_txt_records(ctx, C_HS, bindname);
 255         free(bindname);
 256         return (retvec);
 257 }
 258
 259 void
 260 hesiod_free_list(void *context, char **list) {
 261         char **p;
 262
 263         UNUSED(context);
 264
 265         for (p = list; *p; p++)
 266                 free(*p);
 267         free(list);
 268 }
 269
 270 /*
 271  * This function parses the /etc/hesiod.conf file
 272  */
 273 static int
 274 parse_config_file(struct hesiod_p *ctx, const char *filename) {
 275         char *key, *data, *cp, **cpp;
 276         char buf[MAXDNAME+7];
 277         FILE *fp;
 278
 279         /*
 280          * Clear the existing configuration variable, just in case
 281          * they're set.
 282          */
 283         if (ctx->RHS)
 284                 free(ctx->RHS);
 285         if (ctx->LHS)
 286                 free(ctx->LHS);
 287         ctx->RHS = ctx->LHS = 0;
 288
 289         /*
 290          * Now open and parse the file...
 291          */
 292         if (!(fp = fopen(filename, "r")))
 293                 return (-1);
 294
 295         while (fgets(buf, sizeof(buf), fp) != NULL) {
 296                 cp = buf;
 297                 if (*cp == '#' || *cp == '\n' || *cp == '\r')
 298                         continue;
 299                 while(*cp == ' ' || *cp == '\t')
 300                         cp++;
 301                 key = cp;
 302                 while(*cp != ' ' && *cp != '\t' && *cp != '=')
 303                         cp++;
 304                 *cp++ = '\0';
 305
 306                 while(*cp == ' ' || *cp == '\t' || *cp == '=')
 307                         cp++;
 308                 data = cp;
 309                 while(*cp != ' ' && *cp != '\n' && *cp != '\r')
 310                         cp++;
 311                 *cp++ = '\0';
 312
 313                 if (strcmp(key, "lhs") == 0)
 314                         cpp = &ctx->LHS;
 315                 else if (strcmp(key, "rhs") == 0)
 316                         cpp = &ctx->RHS;
 317                 else
 318                         continue;
 319
 320                 *cpp = malloc(strlen(data) + 1);
 321                 if (!*cpp) {
 322                         errno = ENOMEM;
 323                         goto cleanup;
 324                 }
 325                 strcpy(*cpp, data);
 326         }
 327         fclose(fp);
 328         return (0);
 329
 330  cleanup:
 331         fclose(fp);
 332         if (ctx->RHS)
 333                 free(ctx->RHS);
 334         if (ctx->LHS)
 335                 free(ctx->LHS);
 336         ctx->RHS = ctx->LHS = 0;
 337         return (-1);
 338 }
 339
 340 /*
 341  * Given a DNS class and a DNS name, do a lookup for TXT records, and
 342  * return a list of them.
 343  */
 344 static char **
 345 get_txt_records(struct hesiod_p *ctx, int class, const char *name) {
 346         struct {
 347                 int type;               /* RR type */
 348                 int class;              /* RR class */
 349                 int dlen;               /* len of data section */
 350                 u_char *data;           /* pointer to data */
 351         } rr;
 352         HEADER *hp;
 353         u_char qbuf[MAX_HESRESP], abuf[MAX_HESRESP];
 354         u_char *cp, *erdata, *eom;
 355         char *dst, *edst, **list;
 356         int ancount, qdcount;
 357         int i, j, n, skip;
 358
 359         /*
 360          * Construct the query and send it.
 361          */
 362         n = res_nmkquery(ctx->res, QUERY, name, class, T_TXT, NULL, 0,
 363                          NULL, qbuf, MAX_HESRESP);
 364         if (n < 0) {
 365                 errno = EMSGSIZE;
 366                 return (NULL);
 367         }
 368         n = res_nsend(ctx->res, qbuf, n, abuf, MAX_HESRESP);
 369         if (n < 0) {
 370                 errno = ECONNREFUSED;
 371                 return (NULL);
 372         }
 373         if (n < HFIXEDSZ) {
 374                 errno = EMSGSIZE;
 375                 return (NULL);
 376         }
 377
 378         /*
 379          * OK, parse the result.
 380          */
 381         hp = (HEADER *) abuf;
 382         ancount = ntohs(hp->ancount);
 383         qdcount = ntohs(hp->qdcount);
 384         cp = abuf + sizeof(HEADER);
 385         eom = abuf + n;
 386
 387         /* Skip query, trying to get to the answer section which follows. */
 388         for (i = 0; i < qdcount; i++) {
 389                 skip = dn_skipname(cp, eom);
 390                 if (skip < 0 || cp + skip + QFIXEDSZ > eom) {
 391                         errno = EMSGSIZE;
 392                         return (NULL);
 393                 }
 394                 cp += skip + QFIXEDSZ;
 395         }
 396
 397         list = malloc((ancount + 1) * sizeof(char *));
 398         if (!list) {
 399                 errno = ENOMEM;
 400                 return (NULL);
 401         }
 402         j = 0;
 403         for (i = 0; i < ancount; i++) {
 404                 skip = dn_skipname(cp, eom);
 405                 if (skip < 0) {
 406                         errno = EMSGSIZE;
 407                         goto cleanup;
 408                 }
 409                 cp += skip;
 410                 if (cp + 3 * INT16SZ + INT32SZ > eom) {
 411                         errno = EMSGSIZE;
 412                         goto cleanup;
 413                 }
 414                 rr.type = ns_get16(cp);
 415                 cp += INT16SZ;
 416                 rr.class = ns_get16(cp);
 417                 cp += INT16SZ + INT32SZ;        /* skip the ttl, too */
 418                 rr.dlen = ns_get16(cp);
 419                 cp += INT16SZ;
 420                 if (cp + rr.dlen > eom) {
 421                         errno = EMSGSIZE;
 422                         goto cleanup;
 423                 }
 424                 rr.data = cp;
 425                 cp += rr.dlen;
 426                 if (rr.class != class || rr.type != T_TXT)
 427                         continue;
 428                 if (!(list[j] = malloc(rr.dlen)))
 429                         goto cleanup;
 430                 dst = list[j++];
 431                 edst = dst + rr.dlen;
 432                 erdata = rr.data + rr.dlen;
 433                 cp = rr.data;
 434                 while (cp < erdata) {
 435                         n = (unsigned char) *cp++;
 436                         if (cp + n > eom || dst + n > edst) {
 437                                 errno = EMSGSIZE;
 438                                 goto cleanup;
 439                         }
 440                         memcpy(dst, cp, n);
 441                         cp += n;
 442                         dst += n;
 443                 }
 444                 if (cp != erdata) {
 445                         errno = EMSGSIZE;
 446                         goto cleanup;
 447                 }
 448                 *dst = '\0';
 449         }
 450         list[j] = NULL;
 451         if (j == 0) {
 452                 errno = ENOENT;
 453                 goto cleanup;
 454         }
 455         return (list);
 456
 457  cleanup:
 458         for (i = 0; i < j; i++)
 459                 free(list[i]);
 460         free(list);
 461         return (NULL);
 462 }
 463
 464 struct __res_state *
 465 __hesiod_res_get(void *context) {
 466         struct hesiod_p *ctx = context;
 467
 468         if (!ctx->res) {
 469                 struct __res_state *res;
 470                 res = (struct __res_state *)malloc(sizeof *res);
 471                 if (res == NULL) {
 472                         errno = ENOMEM;
 473                         return (NULL);
 474                 }
 475                 memset(res, 0, sizeof *res);
 476                 __hesiod_res_set(ctx, res, free);
 477         }
 478
 479         return (ctx->res);
 480 }
 481
 482 void
 483 __hesiod_res_set(void *context, struct __res_state *res,
 484                  void (*free_res)(void *)) {
 485         struct hesiod_p *ctx = context;
 486
 487         if (ctx->res && ctx->free_res) {
 488                 res_nclose(ctx->res);
 489                 (*ctx->free_res)(ctx->res);
 490         }
 491
 492         ctx->res = res;
 493         ctx->free_res = free_res;
 494 }
 495
 496 static int
 497 init(struct hesiod_p *ctx) {
 498
 499         if (!ctx->res && !__hesiod_res_get(ctx))
 500                 return (-1);
 501
 502         if (((ctx->res->options & RES_INIT) == 0U) &&
 503             (res_ninit(ctx->res) == -1))
 504                 return (-1);
 505
 506         return (0);
 507 }