dnsinfo/dnsinfo_flatfile.c

   1 /*
   2  * Copyright (c) 2009, 2011, 2012, 2014, 2015, 2017-2019 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 #ifdef  MAIN
  39 #define my_log(__level, __format, ...)  SCPrint(TRUE, stdout, CFSTR(__format "\n"), ## __VA_ARGS__)
  40 #endif  // MAIN
  41
  42 #include "dnsinfo.h"
  43 #include "dnsinfo_private.h"
  44 #include "dnsinfo_create.h"
  45
  46 static uint32_t _dnsinfo_flatfile_flags;
  47
  48 enum {
  49         TOKEN_DOMAIN,
  50         TOKEN_FLAGS,
  51         TOKEN_INTERFACE,
  52         TOKEN_NAMESERVER,
  53         TOKEN_OPTIONS,
  54         TOKEN_PORT,
  55         TOKEN_SEARCH,
  56         TOKEN_SEARCH_ORDER,
  57         TOKEN_SORTLIST,
  58         TOKEN_TIMEOUT,
  59         TOKEN_MAX
  60 };
  61
  62 /*
  63  * tokens
  64  * The supported configuration token strings and enumerated values.
  65  */
  66 static const struct {
  67         const char      *name;
  68         int             token;
  69         int             max_count;
  70 } tokens [] = {
  71         { "domain",             TOKEN_DOMAIN,           1       },
  72         { "flags",              TOKEN_FLAGS,            1       },
  73         { "interface",          TOKEN_INTERFACE,        1       },
  74         { "nameserver",         TOKEN_NAMESERVER,       MAXNS   },
  75         { "options",            TOKEN_OPTIONS,          1       },
  76         { "port",               TOKEN_PORT,             1       },
  77         { "search",             TOKEN_SEARCH,           1       },
  78         { "search_order",       TOKEN_SEARCH_ORDER,     1       },
  79         { "sortlist",           TOKEN_SORTLIST,         1       },
  80         { "timeout",            TOKEN_TIMEOUT,          1       },
  81 };
  82
  83
  84 /*
  85  * _dnsinfo_parse_address
  86  *
  87  * Parse IP address
  88  */
  89 static struct sockaddr *
  90 _dnsinfo_parse_address(char *nameserver)
  91 {
  92         struct addrinfo *ai;
  93         struct addrinfo hints;
  94         int             res;
  95         struct sockaddr *sa     = NULL;
  96
  97         memset(&hints, 0, sizeof(hints));
  98         hints.ai_flags = AI_NUMERICHOST;
  99
 100         res = getaddrinfo(nameserver, NULL, &hints, &ai);
 101         if (res == 0) {
 102                 if ((ai->ai_family == AF_INET) || (ai->ai_family == AF_INET6)) {
 103                         sa = malloc(ai->ai_addrlen);
 104                         memcpy(sa, ai->ai_addr, ai->ai_addrlen);
 105                 }
 106                 freeaddrinfo(ai);
 107         }
 108
 109         return sa;
 110 }
 111
 112
 113 /*
 114  * _dnsinfo_parse_nameserver
 115  *
 116  * Parse arguments to the nameserver token. This is essentially a getaddrinfo(3)
 117  * with AI_NUMERICHOST. However, if the conversion fails, check if the address
 118  * contains an optional trailing '.' followed by a numeric port number.  If found,
 119  * remove the port number and retry the conversion (e.g. 127.0.0.1.55 or ::1.55).
 120  */
 121 static struct sockaddr *
 122 _dnsinfo_parse_nameserver(char *token)
 123 {
 124         char            *dot;
 125         long            number;
 126         struct sockaddr *sa;
 127
 128         sa = _dnsinfo_parse_address(token);
 129         if (sa != NULL) {
 130                 return sa;
 131         }
 132
 133         // if we could not parse address, attempt to remove
 134         // an optional trailing port number
 135         dot = strrchr(token, '.');
 136         if (dot == NULL) {
 137                 return NULL;
 138         }
 139
 140         number = strtol(dot + 1, NULL, 10);
 141         if ((number < 0) || (number > UINT16_MAX)) {
 142                 return NULL;
 143         }
 144
 145         *dot = '\0';
 146         sa = _dnsinfo_parse_address(token);
 147         if (sa != NULL) {
 148                 in_port_t       port    = htons(number);
 149
 150                 switch (sa->sa_family) {
 151                         case AF_INET :
 152                                 /* ALIGN: cast ok, sockaddr was malloc'd */
 153                                 ((struct sockaddr_in *)(void *)sa)->sin_port = port;
 154                                 break;
 155                         case AF_INET6 :
 156                                 /* ALIGN: cast ok, sockaddr was malloc'd */
 157                                 ((struct sockaddr_in6 *)(void *)sa)->sin6_port = port;
 158                                 break;
 159                 }
 160         }
 161
 162         return sa;
 163 }
 164
 165
 166 /*
 167  * _dnsinfo_parse_sortaddr
 168  *
 169  * Parse arguments to the sortlist token.
 170  */
 171 static dns_sortaddr_t *
 172 _dnsinfo_parse_sortaddr(char *token)
 173 {
 174         struct in_addr          addr;
 175         struct in_addr          mask;
 176         struct sockaddr         *sa;
 177         char                    *slash;
 178         dns_sortaddr_t          *sortaddr       = NULL;
 179
 180         slash = strchr(token, '/');
 181         if (slash != NULL) {
 182                 *slash = '\0';
 183         }
 184
 185         sa = _dnsinfo_parse_address(token);
 186         if (sa == NULL) {
 187                 // if we could not parse the address
 188                 goto done;
 189         } else if (sa->sa_family != AF_INET) {
 190                 // if not AF_INET
 191                 goto done;
 192         } else {
 193                 /* ALIGN: cast ok, sockaddr was malloc'd */
 194                 addr = ((struct sockaddr_in *)(void *)sa)->sin_addr;
 195                 free(sa);
 196                 sa = NULL;
 197         }
 198
 199         if (slash != NULL) {
 200                 sa = _dnsinfo_parse_address(slash + 1);
 201                 if (sa == NULL) {
 202                         // if we could not parse the provided mask
 203                         goto done;
 204                 } else if (sa->sa_family != AF_INET) {
 205                         // if mask not AF_INET
 206                         goto done;
 207                 } else {
 208                         /* ALIGN: cast ok, sockaddr was malloc'd */
 209                         mask = ((struct sockaddr_in *)(void *)sa)->sin_addr;
 210                         free(sa);
 211                         sa = NULL;
 212                 }
 213         } else {
 214                 in_addr_t       a;
 215                 in_addr_t       m;
 216
 217                 a = ntohl(addr.s_addr);
 218                 if (IN_CLASSA(a)) {
 219                         m = IN_CLASSA_NET;
 220                 } else if (IN_CLASSB(a)) {
 221                         m = IN_CLASSB_NET;
 222                 } else if (IN_CLASSC(a)) {
 223                         m = IN_CLASSC_NET;
 224                 } else {
 225                         goto done;
 226                 }
 227
 228                 mask.s_addr = htonl(m);
 229         }
 230
 231         sortaddr = malloc(sizeof(*sortaddr));
 232         sortaddr->address = addr;
 233         sortaddr->mask    = mask;
 234
 235     done :
 236
 237         if (sa != NULL) free(sa);
 238         return sortaddr;
 239 }
 240
 241
 242 /*
 243  * _dnsinfo_flatfile_set_flags
 244  *
 245  * Set the default resolver flags.
 246  */
 247 __private_extern__
 248 void
 249 _dnsinfo_flatfile_set_flags(uint32_t flags)
 250 {
 251         _dnsinfo_flatfile_flags = flags;
 252         return;
 253 }
 254
 255
 256 static void
 257 _dnsinfo_flatfile_update_flags(dns_create_resolver_t *_resolver)
 258 {
 259         uint32_t                new_flags;
 260         uint32_t                old_flags;
 261         _dns_resolver_buf_t     *resolver       = (_dns_resolver_buf_t *)*_resolver;
 262
 263         old_flags = ntohl(resolver->resolver.flags);
 264         new_flags = old_flags | _dnsinfo_flatfile_flags;
 265         _dns_resolver_set_flags(_resolver, new_flags);
 266         return;
 267 }
 268
 269
 270 /*
 271  * _dnsinfo_flatfile_create_resolver
 272  *
 273  * Create a new dns resolver configuration from the configuration file at the
 274  * specified path. (e.g. /etc/resolv.conf or /etc/resolver/apple.com)
 275  */
 276 static dns_create_resolver_t
 277 _dnsinfo_flatfile_create_resolver(const char *dir, const char *path)
 278 {
 279         char                    *buf;
 280         uint32_t                config_flags            = 0;
 281         FILE                    *f;
 282         char                    filename[FILENAME_MAX];
 283         size_t                  len                     = 0;
 284         char                    *line                   = NULL;
 285         dns_create_resolver_t   res                     = NULL;
 286         const char              *sep                    = " \t";
 287         int                     token_count[TOKEN_MAX]  = { 0 };
 288
 289         filename[0] = 0;
 290         if (dir != NULL) {
 291                 strlcpy(filename, dir, sizeof(filename));
 292                 strlcat(filename, "/", sizeof(filename));
 293         }
 294         strlcat(filename, path, sizeof(filename));
 295
 296         f = fopen(filename, "r");
 297         if (f == NULL) return NULL;
 298
 299         while ((buf = fgetln(f, &len)) != NULL) {
 300                 char    *lineptr;
 301                 int     max_count;
 302                 int     token;
 303                 char    *word;
 304
 305                 if (len == 0) continue;
 306                 if (buf[len-1] == '\n') buf[len-1] = '\0';
 307
 308                 line = reallocf(line, len+1);
 309                 if (line == NULL) continue;
 310
 311                 strlcpy(line, buf, len+1);
 312
 313                 // parse the first word of the line (the config token)
 314                 lineptr = line;
 315                 word = strsep(&lineptr, sep);
 316                 if (word == NULL) {
 317                         // if empty line
 318                         continue;
 319                 }
 320                 if (word[0] == ';' || word[0] == '#') {
 321                         // if comment
 322                         continue;
 323                 }
 324
 325                 // translate config token to enumerated value
 326                 token = -1;
 327                 for (size_t i = 0; i < sizeof(tokens) / sizeof(tokens[0]); i++) {
 328                         if (strcasecmp(word, tokens[i].name) == 0) {
 329                                 token     = tokens[i].token;
 330                                 max_count = tokens[i].max_count;
 331                                 break;
 332                         }
 333                 }
 334                 if (token == -1) {
 335                         // if not a recognized token
 336                         continue;
 337                 }
 338
 339                 // parse the next word of the line (the config option)
 340                 word = strsep(&lineptr, sep);
 341                 if (word == NULL) {
 342                         // if no option
 343                         continue;
 344                 }
 345                 if (++token_count[token] > max_count) {
 346                         // if too many options
 347                         continue;
 348                 }
 349
 350                 // create resolver
 351                 if (res == NULL) {
 352                         res = _dns_resolver_create();
 353                         if (res == NULL) {
 354                                 // if we could not create a resolver
 355                                 goto done;
 356                         }
 357                 }
 358
 359                 switch (token) {
 360                         case TOKEN_DOMAIN: {
 361                                 size_t  len;
 362
 363                                 len = strlen(word);
 364                                 while ((len > 0) && (word[len - 1] == '.')) {
 365                                         // trim trailing '.'
 366                                         word[--len] = '\0';
 367                                 }
 368                                 if (len > 0) {
 369                                         _dns_resolver_set_domain(&res, word);
 370                                 }
 371                                 break;
 372                         }
 373
 374                         case TOKEN_FLAGS: {
 375                                 while (word != NULL) {
 376                                         if (word[0] != '\0') {
 377                                                 if (strcasecmp(word, "scoped") == 0) {
 378                                                         config_flags |= DNS_RESOLVER_FLAGS_SCOPED;
 379                                                 } else if (strcasecmp(word, "a") == 0) {
 380                                                         config_flags |= DNS_RESOLVER_FLAGS_REQUEST_A_RECORDS;
 381                                                 } else if (strcasecmp(word, "aaaa") == 0) {
 382                                                         config_flags |= DNS_RESOLVER_FLAGS_REQUEST_AAAA_RECORDS;
 383                                                 }
 384                                         }
 385                                         word = strsep(&lineptr, sep);
 386                                 }
 387                                 break;
 388                         }
 389
 390                         case TOKEN_INTERFACE: {
 391                                 unsigned int    if_index;
 392
 393                                 if_index = if_nametoindex(word);
 394                                 if (if_index > 0) {
 395                                         _dns_resolver_set_if_index(&res, if_index, word);
 396                                 }
 397                                 break;
 398                         }
 399
 400                         case TOKEN_NAMESERVER: {
 401                                 struct sockaddr *sa;
 402
 403                                 sa = _dnsinfo_parse_nameserver(word);
 404                                 if (sa != NULL) {
 405                                         _dns_resolver_add_nameserver(&res, sa);
 406                                         free(sa);
 407                                 }
 408                                 break;
 409                         }
 410
 411                         case TOKEN_OPTIONS: {
 412                                 char    *options        = NULL;
 413
 414                                 while (word != NULL) {
 415                                         if (word[0] != '\0') {
 416                                                 if (options == NULL) {
 417                                                         options = malloc(len+1);
 418                                                         if (options == NULL) break;
 419
 420                                                         strlcpy(options, word, len+1);
 421                                                 } else {
 422                                                         strlcat(options, " ", len+1);
 423                                                         strlcat(options, word, len+1);
 424                                                 }
 425                                         }
 426                                         word = strsep(&lineptr, sep);
 427                                 }
 428
 429                                 if (options != NULL) {
 430                                         _dns_resolver_set_options(&res, options);
 431                                         free(options);
 432                                 }
 433                                 break;
 434                         }
 435
 436                         case TOKEN_PORT: {
 437                                 long    number  = -1;
 438
 439                                 number = strtol(word, NULL, 0);
 440                                 if (number < 0 || number > UINT16_MAX) break;
 441                                 _dns_resolver_set_port(&res, number);
 442                                 break;
 443                         }
 444
 445                         case TOKEN_SEARCH: {
 446                                 int     n       = 0;
 447
 448                                 // multiple search domains are supported
 449                                 while ((word != NULL) && (n++ < MAXDNSRCH)) {
 450                                         size_t  len;
 451
 452                                         len = strlen(word);
 453                                         while ((len > 0) && (word[len - 1] == '.')) {
 454                                                 // trim trailing '.'
 455                                                 word[--len] = '\0';
 456                                         }
 457                                         if (len > 0) {
 458                                                 _dns_resolver_add_search(&res, word);
 459                                         }
 460                                         word = strsep(&lineptr, sep);
 461                                 }
 462                                 break;
 463                         }
 464
 465                         case TOKEN_SEARCH_ORDER: {
 466                                 long    number  = -1;
 467
 468                                 number = strtol(word, NULL, 0);
 469                                 if (number < 0 || number > (long)UINT32_MAX) break;
 470                                 _dns_resolver_set_order(&res, (uint32_t)number);
 471                                 break;
 472                         }
 473
 474                         case TOKEN_SORTLIST: {
 475                                 int     n       = 0;
 476
 477                                 while ((word != NULL) && (n++ < MAXRESOLVSORT)) {
 478                                         dns_sortaddr_t  *sortaddr;
 479
 480                                         sortaddr = _dnsinfo_parse_sortaddr(word);
 481                                         if (sortaddr == NULL) break;
 482                                         _dns_resolver_add_sortaddr(&res, sortaddr);
 483                                         free(sortaddr);
 484                                         word = strsep(&lineptr, sep);
 485                                 }
 486                                 break;
 487                         }
 488
 489                         case TOKEN_TIMEOUT: {
 490                                 long    number  = -1;
 491
 492                                 number = strtol(word, NULL, 0);
 493                                 if (number < 0 || number > (long)UINT32_MAX) break;
 494                                 _dns_resolver_set_timeout(&res, (uint32_t)number);
 495                                 break;
 496                         }
 497                 }
 498         }
 499
 500         // set the domain to the basename of the path if not specified
 501         if ((res != NULL) && (token_count[TOKEN_DOMAIN] == 0)) {
 502                 const char      *domain;
 503
 504                 domain = strrchr(path, '/');
 505                 if (domain == NULL) {
 506                         domain = path;
 507                 } else {
 508                         domain = domain + 1;
 509                 }
 510                 _dns_resolver_set_domain(&res, domain);
 511         }
 512
 513         if (res != NULL) {
 514                 // config flags should overwrite any default flags
 515                 if (config_flags != 0) {
 516                         _dns_resolver_set_flags(&res, config_flags);
 517                 } else {
 518                         _dnsinfo_flatfile_update_flags(&res);
 519                 }
 520         }
 521
 522     done :
 523
 524         if (line != NULL) free(line);
 525         fclose(f);
 526         return res;
 527 }
 528
 529
 530 /*
 531  * _dnsinfo_flatfile_add_resolvers
 532  *
 533  * Parse the files in the resolver config directory (/etc/resolver) and add each
 534  * resolver to the dns config.
 535  */
 536 __private_extern__
 537 void
 538 _dnsinfo_flatfile_add_resolvers(dns_create_config_t *config)
 539 {
 540         struct dirent           *de;
 541         DIR                     *dp;
 542         dns_create_resolver_t   res;
 543
 544         dp = opendir(_PATH_RESOLVER_DIR);
 545         if (dp == NULL) {
 546                 return;
 547         }
 548
 549         while ((de = readdir(dp)) != NULL) {
 550                 if (strcmp(de->d_name, ".") == 0 ||
 551                     strcmp(de->d_name, "..") == 0) continue;
 552
 553                 res = _dnsinfo_flatfile_create_resolver(_PATH_RESOLVER_DIR, de->d_name);
 554                 if (res != NULL) {
 555                         _dns_configuration_add_resolver(config, res);
 556                         _dns_resolver_free(&res);
 557                 }
 558         }
 559
 560         closedir(dp);
 561         return;
 562 }
 563
 564
 565 #ifdef  MAIN
 566 #undef  MAIN
 567
 568 #include "dnsinfo_logging.h"
 569 #include "dnsinfo_copy.c"
 570
 571 int
 572 main(int argc, char **argv)
 573 {
 574         dns_config_t            *dns_config     = NULL;
 575         _dns_config_buf_t       *dns_config_buf = NULL;
 576         dns_create_config_t     dns_create_config;
 577         dns_create_resolver_t   dns_create_resolver;
 578
 579         dns_create_resolver = _dnsinfo_flatfile_create_resolver(NULL, _PATH_RESCONF);
 580         _dns_resolver_free(&dns_create_resolver);
 581
 582         dns_create_config = _dns_configuration_create();
 583         if (dns_create_config != NULL) {
 584                 size_t          n;
 585
 586                 _dnsinfo_flatfile_add_resolvers(&dns_create_config);
 587
 588                 n = sizeof(_dns_config_buf_t);
 589                 n += ntohl(((_dns_config_buf_t *)dns_create_config)->n_attribute);
 590                 dns_config_buf = _dns_configuration_buffer_create((void *)dns_create_config, n);
 591                 _dns_configuration_free(&dns_create_config);
 592         }
 593
 594         if (dns_config_buf != NULL) {
 595                 dns_config = _dns_configuration_buffer_expand(dns_config_buf);
 596                 if (dns_config == NULL) {
 597                         // if we were unable to expand the configuration
 598                         _dns_configuration_buffer_free(&dns_config_buf);
 599                 }
 600         }
 601
 602         if (dns_config != NULL) {
 603                 _dns_configuration_log(dns_config, TRUE, NULL);
 604                 free(dns_config);
 605         }
 606
 607         return 0;
 608 }
 609
 610 #endif