dnsinfo/dnsinfo_flatfile.c

   1 /*
   2  * Copyright (c) 2009, 2011, 2012, 2014, 2015 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <dirent.h>
  25 #include <fcntl.h>
  26 #include <libgen.h>
  27 #include <netdb.h>
  28 #include <resolv.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <net/if.h>
  33 #include <sys/dir.h>
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <unistd.h>
  37
  38 #include "dnsinfo.h"
  39 #include "dnsinfo_private.h"
  40 #include "dnsinfo_create.h"
  41
  42 static uint32_t _dnsinfo_flatfile_flags;
  43
  44 enum {
  45         TOKEN_DOMAIN,
  46         TOKEN_FLAGS,
  47         TOKEN_INTERFACE,
  48         TOKEN_NAMESERVER,
  49         TOKEN_OPTIONS,
  50         TOKEN_PORT,
  51         TOKEN_SEARCH,
  52         TOKEN_SEARCH_ORDER,
  53         TOKEN_SORTLIST,
  54         TOKEN_TIMEOUT,
  55         TOKEN_MAX
  56 };
  57
  58 /*
  59  * tokens
  60  * The supported configuration token strings and enumerated values.
  61  */
  62 static const struct {
  63         const char      *name;
  64         int             token;
  65         int             max_count;
  66 } tokens [] = {
  67         { "domain",             TOKEN_DOMAIN,           1       },
  68         { "flags",              TOKEN_FLAGS,            1       },
  69         { "interface",          TOKEN_INTERFACE,        1       },
  70         { "nameserver",         TOKEN_NAMESERVER,       MAXNS   },
  71         { "options",            TOKEN_OPTIONS,          1       },
  72         { "port",               TOKEN_PORT,             1       },
  73         { "search",             TOKEN_SEARCH,           1       },
  74         { "search_order",       TOKEN_SEARCH_ORDER,     1       },
  75         { "sortlist",           TOKEN_SORTLIST,         1       },
  76         { "timeout",            TOKEN_TIMEOUT,          1       },
  77 };
  78
  79
  80 /*
  81  * _dnsinfo_parse_address
  82  *
  83  * Parse IP address
  84  */
  85 static struct sockaddr *
  86 _dnsinfo_parse_address(char *nameserver)
  87 {
  88         struct addrinfo *ai;
  89         struct addrinfo hints;
  90         int             res;
  91         struct sockaddr *sa     = NULL;
  92
  93         memset(&hints, 0, sizeof(hints));
  94         hints.ai_flags = AI_NUMERICHOST;
  95
  96         res = getaddrinfo(nameserver, NULL, &hints, &ai);
  97         if (res == 0) {
  98                 if ((ai->ai_family == AF_INET) || (ai->ai_family == AF_INET6)) {
  99                         sa = malloc(ai->ai_addrlen);
 100                         memcpy(sa, ai->ai_addr, ai->ai_addrlen);
 101                 }
 102                 freeaddrinfo(ai);
 103         }
 104
 105         return sa;
 106 }
 107
 108
 109 /*
 110  * _dnsinfo_parse_nameserver
 111  *
 112  * Parse arguments to the nameserver token. This is essentially a getaddrinfo(3)
 113  * with AI_NUMERICHOST. However, if the conversion fails, check if the address
 114  * contains an optional trailing '.' followed by a numeric port number.  If found,
 115  * remove the port number and retry the conversion (e.g. 127.0.0.1.55 or ::1.55).
 116  */
 117 static struct sockaddr *
 118 _dnsinfo_parse_nameserver(char *token)
 119 {
 120         char            *dot;
 121         long            number;
 122         struct sockaddr *sa;
 123
 124         sa = _dnsinfo_parse_address(token);
 125         if (sa != NULL) {
 126                 return sa;
 127         }
 128
 129         // if we could not parse address, attempt to remove
 130         // an optional trailing port number
 131         dot = strrchr(token, '.');
 132         if (dot == NULL) {
 133                 return NULL;
 134         }
 135
 136         number = strtol(dot + 1, NULL, 10);
 137         if ((number < 0) || (number > UINT16_MAX)) {
 138                 return NULL;
 139         }
 140
 141         *dot = '\0';
 142         sa = _dnsinfo_parse_address(token);
 143         if (sa != NULL) {
 144                 in_port_t       port    = htons(number);
 145
 146                 switch (sa->sa_family) {
 147                         case AF_INET :
 148                                 /* ALIGN: cast ok, sockaddr was malloc'd */
 149                                 ((struct sockaddr_in *)(void *)sa)->sin_port = port;
 150                                 break;
 151                         case AF_INET6 :
 152                                 /* ALIGN: cast ok, sockaddr was malloc'd */
 153                                 ((struct sockaddr_in6 *)(void *)sa)->sin6_port = port;
 154                                 break;
 155                 }
 156         }
 157
 158         return sa;
 159 }
 160
 161
 162 /*
 163  * _dnsinfo_parse_sortaddr
 164  *
 165  * Parse arguments to the sortlist token.
 166  */
 167 static dns_sortaddr_t *
 168 _dnsinfo_parse_sortaddr(char *token)
 169 {
 170         struct in_addr          addr;
 171         struct in_addr          mask;
 172         struct sockaddr         *sa;
 173         char                    *slash;
 174         dns_sortaddr_t          *sortaddr       = NULL;
 175
 176         slash = strchr(token, '/');
 177         if (slash != NULL) {
 178                 *slash = '\0';
 179         }
 180
 181         sa = _dnsinfo_parse_address(token);
 182         if (sa == NULL) {
 183                 // if we could not parse the address
 184                 goto done;
 185         } else if (sa->sa_family != AF_INET) {
 186                 // if not AF_INET
 187                 goto done;
 188         } else {
 189                 /* ALIGN: cast ok, sockaddr was malloc'd */
 190                 addr = ((struct sockaddr_in *)(void *)sa)->sin_addr;
 191                 free(sa);
 192                 sa = NULL;
 193         }
 194
 195         if (slash != NULL) {
 196                 sa = _dnsinfo_parse_address(slash + 1);
 197                 if (sa == NULL) {
 198                         // if we could not parse the provided mask
 199                         goto done;
 200                 } else if (sa->sa_family != AF_INET) {
 201                         // if mask not AF_INET
 202                         goto done;
 203                 } else {
 204                         /* ALIGN: cast ok, sockaddr was malloc'd */
 205                         mask = ((struct sockaddr_in *)(void *)sa)->sin_addr;
 206                         free(sa);
 207                         sa = NULL;
 208                 }
 209         } else {
 210                 in_addr_t       a;
 211                 in_addr_t       m;
 212
 213                 a = ntohl(addr.s_addr);
 214                 if (IN_CLASSA(a)) {
 215                         m = IN_CLASSA_NET;
 216                 } else if (IN_CLASSB(a)) {
 217                         m = IN_CLASSB_NET;
 218                 } else if (IN_CLASSC(a)) {
 219                         m = IN_CLASSC_NET;
 220                 } else {
 221                         goto done;
 222                 }
 223
 224                 mask.s_addr = htonl(m);
 225         }
 226
 227         sortaddr = malloc(sizeof(*sortaddr));
 228         sortaddr->address = addr;
 229         sortaddr->mask    = mask;
 230
 231     done :
 232
 233         if (sa != NULL) free(sa);
 234         return sortaddr;
 235 }
 236
 237
 238 /*
 239  * _dnsinfo_flatfile_set_flags
 240  *
 241  * Set the default resolver flags.
 242  */
 243 __private_extern__
 244 void
 245 _dnsinfo_flatfile_set_flags(uint32_t flags)
 246 {
 247         _dnsinfo_flatfile_flags = flags;
 248         return;
 249 }
 250
 251
 252 static void
 253 _dnsinfo_flatfile_update_flags(dns_create_resolver_t *_resolver)
 254 {
 255         uint32_t                new_flags;
 256         uint32_t                old_flags;
 257         _dns_resolver_buf_t     *resolver       = (_dns_resolver_buf_t *)*_resolver;
 258
 259         old_flags = ntohl(resolver->resolver.flags);
 260         new_flags = old_flags | _dnsinfo_flatfile_flags;
 261         _dns_resolver_set_flags(_resolver, new_flags);
 262         return;
 263 }
 264
 265
 266 /*
 267  * _dnsinfo_flatfile_create_resolver
 268  *
 269  * Create a new dns resolver configuration from the configuration file at the
 270  * specified path. (e.g. /etc/resolv.conf or /etc/resolver/apple.com)
 271  */
 272 static dns_create_resolver_t
 273 _dnsinfo_flatfile_create_resolver(const char *dir, const char *path)
 274 {
 275         char                    *buf;
 276         uint32_t                config_flags            = 0;
 277         FILE                    *f;
 278         char                    filename[FILENAME_MAX];
 279         size_t                  len                     = 0;
 280         char                    *line                   = NULL;
 281         dns_create_resolver_t   res                     = NULL;
 282         const char              *sep                    = " \t";
 283         int                     token_count[TOKEN_MAX]  = { 0 };
 284
 285         filename[0] = 0;
 286         if (dir != NULL) {
 287                 strlcpy(filename, dir, sizeof(filename));
 288                 strlcat(filename, "/", sizeof(filename));
 289         }
 290         strlcat(filename, path, sizeof(filename));
 291
 292         f = fopen(filename, "r");
 293         if (f == NULL) return NULL;
 294
 295         while ((buf = fgetln(f, &len)) != NULL) {
 296                 int     i;
 297                 char    *lineptr;
 298                 int     max_count;
 299                 int     token;
 300                 char    *word;
 301
 302                 if (len == 0) continue;
 303                 if (buf[len-1] == '\n') buf[len-1] = '\0';
 304
 305                 line = reallocf(line, len+1);
 306                 if (line == NULL) continue;
 307
 308                 strncpy(line, buf, len);
 309                 line[len] = '\0';
 310
 311                 // parse the first word of the line (the config token)
 312                 lineptr = line;
 313                 word = strsep(&lineptr, sep);
 314                 if (word == NULL) {
 315                         // if empty line
 316                         continue;
 317                 }
 318                 if (word[0] == ';' || word[0] == '#') {
 319                         // if comment
 320                         continue;
 321                 }
 322
 323                 // translate config token to enumerated value
 324                 token = -1;
 325                 for (i = 0; i < sizeof(tokens) / sizeof(tokens[0]); i++) {
 326                         if (strcasecmp(word, tokens[i].name) == 0) {
 327                                 token     = tokens[i].token;
 328                                 max_count = tokens[i].max_count;
 329                                 break;
 330                         }
 331                 }
 332                 if (token == -1) {
 333                         // if not a recognized token
 334                         continue;
 335                 }
 336
 337                 // parse the next word of the line (the config option)
 338                 word = strsep(&lineptr, sep);
 339                 if (word == NULL) {
 340                         // if no option
 341                         continue;
 342                 }
 343                 if (++token_count[token] > max_count) {
 344                         // if too many options
 345                         continue;
 346                 }
 347
 348                 // create resolver
 349                 if (res == NULL) {
 350                         res = _dns_resolver_create();
 351                         if (res == NULL) {
 352                                 // if we could not create a resolver
 353                                 goto done;
 354                         }
 355                 }
 356
 357                 switch (token) {
 358                         case TOKEN_DOMAIN: {
 359                                 size_t  len;
 360
 361                                 len = strlen(word);
 362                                 while ((len > 0) && (word[len - 1] == '.')) {
 363                                         // trim trailing '.'
 364                                         word[--len] = '\0';
 365                                 }
 366                                 if (len > 0) {
 367                                         _dns_resolver_set_domain(&res, word);
 368                                 }
 369                                 break;
 370                         }
 371
 372                         case TOKEN_FLAGS: {
 373                                 while (word != NULL) {
 374                                         if (word[0] != '\0') {
 375                                                 if (strcasecmp(word, "scoped") == 0) {
 376                                                         config_flags |= DNS_RESOLVER_FLAGS_SCOPED;
 377                                                 } else if (strcasecmp(word, "a") == 0) {
 378                                                         config_flags |= DNS_RESOLVER_FLAGS_REQUEST_A_RECORDS;
 379                                                 } else if (strcasecmp(word, "aaaa") == 0) {
 380                                                         config_flags |= DNS_RESOLVER_FLAGS_REQUEST_AAAA_RECORDS;
 381                                                 }
 382                                         }
 383                                         word = strsep(&lineptr, sep);
 384                                 }
 385                                 break;
 386                         }
 387
 388                         case TOKEN_INTERFACE: {
 389                                 unsigned int    if_index;
 390
 391                                 if_index = if_nametoindex(word);
 392                                 if (if_index > 0) {
 393                                         _dns_resolver_set_if_index(&res, if_index);
 394                                 }
 395                                 break;
 396                         }
 397
 398                         case TOKEN_NAMESERVER: {
 399                                 struct sockaddr *sa;
 400
 401                                 sa = _dnsinfo_parse_nameserver(word);
 402                                 if (sa != NULL) {
 403                                         _dns_resolver_add_nameserver(&res, sa);
 404                                         free(sa);
 405                                 }
 406                                 break;
 407                         }
 408
 409                         case TOKEN_OPTIONS: {
 410                                 char    *options        = NULL;
 411
 412                                 while (word != NULL) {
 413                                         if (word[0] != '\0') {
 414                                                 if (options == NULL) {
 415                                                         options = malloc(len+1);
 416                                                         if (options == NULL) break;
 417
 418                                                         strlcpy(options, word, len+1);
 419                                                 } else {
 420                                                         strlcat(options, " ", len+1);
 421                                                         strlcat(options, word, len+1);
 422                                                 }
 423                                         }
 424                                         word = strsep(&lineptr, sep);
 425                                 }
 426
 427                                 if (options != NULL) {
 428                                         _dns_resolver_set_options(&res, options);
 429                                         free(options);
 430                                 }
 431                                 break;
 432                         }
 433
 434                         case TOKEN_PORT: {
 435                                 long    number  = -1;
 436
 437                                 number = strtol(word, NULL, 0);
 438                                 if (number < 0 || number > UINT16_MAX) break;
 439                                 _dns_resolver_set_port(&res, number);
 440                                 break;
 441                         }
 442
 443                         case TOKEN_SEARCH: {
 444                                 int     n       = 0;
 445
 446                                 // multiple search domains are supported
 447                                 while ((word != NULL) && (n++ < MAXDNSRCH)) {
 448                                         size_t  len;
 449
 450                                         len = strlen(word);
 451                                         while ((len > 0) && (word[len - 1] == '.')) {
 452                                                 // trim trailing '.'
 453                                                 word[--len] = '\0';
 454                                         }
 455                                         if (len > 0) {
 456                                                 _dns_resolver_add_search(&res, word);
 457                                         }
 458                                         word = strsep(&lineptr, sep);
 459                                 }
 460                                 break;
 461                         }
 462
 463                         case TOKEN_SEARCH_ORDER: {
 464                                 long    number  = -1;
 465
 466                                 number = strtol(word, NULL, 0);
 467                                 if (number < 0 || number > UINT32_MAX) break;
 468                                 _dns_resolver_set_order(&res, (uint32_t)number);
 469                                 break;
 470                         }
 471
 472                         case TOKEN_SORTLIST: {
 473                                 int     n       = 0;
 474
 475                                 while ((word != NULL) && (n++ < MAXRESOLVSORT)) {
 476                                         dns_sortaddr_t  *sortaddr;
 477
 478                                         sortaddr = _dnsinfo_parse_sortaddr(word);
 479                                         if (sortaddr == NULL) break;
 480                                         _dns_resolver_add_sortaddr(&res, sortaddr);
 481                                         free(sortaddr);
 482                                         word = strsep(&lineptr, sep);
 483                                 }
 484                                 break;
 485                         }
 486
 487                         case TOKEN_TIMEOUT: {
 488                                 long    number  = -1;
 489
 490                                 number = strtol(word, NULL, 0);
 491                                 if (number < 0 || number > UINT32_MAX) break;
 492                                 _dns_resolver_set_timeout(&res, (uint32_t)number);
 493                                 break;
 494                         }
 495                 }
 496         }
 497         if (line != NULL) free(line);
 498
 499         // set the domain to the basename of the path if not specified
 500         if ((res != NULL) && (token_count[TOKEN_DOMAIN] == 0)) {
 501                 const char      *domain;
 502
 503                 domain = strrchr(path, '/');
 504                 if (domain == NULL) {
 505                         domain = path;
 506                 } else {
 507                         domain = domain + 1;
 508                 }
 509                 _dns_resolver_set_domain(&res, domain);
 510         }
 511
 512         if (res != NULL) {
 513                 // config flags should overwrite any default flags
 514                 if (config_flags != 0) {
 515                         _dns_resolver_set_flags(&res, config_flags);
 516                 } else {
 517                         _dnsinfo_flatfile_update_flags(&res);
 518                 }
 519         }
 520
 521     done :
 522
 523         fclose(f);
 524         return res;
 525 }
 526
 527
 528 /*
 529  * _dnsinfo_flatfile_add_resolvers
 530  *
 531  * Parse the files in the resolver config directory (/etc/resolver) and add each
 532  * resolver to the dns config.
 533  */
 534 __private_extern__
 535 void
 536 _dnsinfo_flatfile_add_resolvers(dns_create_config_t *config)
 537 {
 538         struct dirent           *de;
 539         DIR                     *dp;
 540         dns_create_resolver_t   res;
 541
 542         dp = opendir(_PATH_RESOLVER_DIR);
 543         if (dp == NULL) {
 544                 return;
 545         }
 546
 547         while ((de = readdir(dp)) != NULL) {
 548                 if (strcmp(de->d_name, ".") == 0 ||
 549                     strcmp(de->d_name, "..") == 0) continue;
 550
 551                 res = _dnsinfo_flatfile_create_resolver(_PATH_RESOLVER_DIR, de->d_name);
 552                 if (res != NULL) {
 553                         _dns_configuration_add_resolver(config, res);
 554                         _dns_resolver_free(&res);
 555                 }
 556         }
 557
 558         closedir(dp);
 559         return;
 560 }
 561
 562
 563 #ifdef  MAIN
 564 #undef  MAIN
 565
 566 #include "dnsinfo_copy.c"
 567
 568 int
 569 main(int argc, char **argv)
 570 {
 571         uint8_t                 *buf;
 572         dns_config_t            *config;
 573         dns_create_config_t     create_config;
 574         _dns_config_buf_t       *config_buf;
 575         uint32_t                n_config;
 576         uint32_t                n_padding;
 577         dns_create_resolver_t   resolver;
 578
 579         resolver = _dnsinfo_flatfile_create_resolver(NULL, _PATH_RESCONF);
 580
 581         create_config = _dns_configuration_create();
 582         _dnsinfo_flatfile_add_resolvers(&create_config);
 583
 584         config_buf = (_dns_config_buf_t *)create_config;
 585         n_config  = sizeof(_dns_config_buf_t) + ntohl(config_buf->n_attribute);
 586         n_padding = ntohl(config_buf->n_padding);
 587         buf = malloc(n_config + n_padding);
 588         bcopy((void *)config_buf, buf, n_config);
 589         bzero(&buf[n_config], n_padding);
 590         config = _dns_configuration_expand_config((_dns_config_buf_t *)buf);
 591
 592         return 0;
 593 }
 594
 595 #endif