usr/src/lib/libresolv2/common/irs/hesiod.c

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