dnsinfo/dnsinfo_flatfile.c

   1 /*
   2  * Copyright (c) 2009, 2011, 2012, 2014, 2015, 2017-2020 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 #include <SystemConfiguration/SCPrivate.h>      // for SC_log
  38
  39 #ifdef  SC_LOG_HANDLE
  40 #include <os/log.h>
  41 os_log_t        SC_LOG_HANDLE(void);
  42 #endif  //SC_LOG_HANDLE
  43
  44 #include "dnsinfo.h"
  45 #include "dnsinfo_private.h"
  46 #include "dnsinfo_create.h"
  47
  48 static uint32_t _dnsinfo_flatfile_flags;
  49
  50 enum {
  51         TOKEN_DOMAIN,
  52         TOKEN_FLAGS,
  53         TOKEN_INTERFACE,
  54         TOKEN_NAMESERVER,
  55         TOKEN_OPTIONS,
  56         TOKEN_PORT,
  57         TOKEN_SEARCH,
  58         TOKEN_SEARCH_ORDER,
  59         TOKEN_SORTLIST,
  60         TOKEN_TIMEOUT,
  61         TOKEN_MAX
  62 };
  63
  64 /*
  65  * tokens
  66  * The supported configuration token strings and enumerated values.
  67  */
  68 static const struct {
  69         const char      *name;
  70         int             token;
  71         int             max_count;
  72 } tokens [] = {
  73         { "domain",             TOKEN_DOMAIN,           1       },
  74         { "flags",              TOKEN_FLAGS,            1       },
  75         { "interface",          TOKEN_INTERFACE,        1       },
  76         { "nameserver",         TOKEN_NAMESERVER,       MAXNS   },
  77         { "options",            TOKEN_OPTIONS,          1       },
  78         { "port",               TOKEN_PORT,             1       },
  79         { "search",             TOKEN_SEARCH,           1       },
  80         { "search_order",       TOKEN_SEARCH_ORDER,     1       },
  81         { "sortlist",           TOKEN_SORTLIST,         1       },
  82         { "timeout",            TOKEN_TIMEOUT,          1       },
  83 };
  84
  85
  86 /*
  87  * _dnsinfo_parse_address
  88  *
  89  * Parse IP address
  90  */
  91 static struct sockaddr *
  92 _dnsinfo_parse_address(char *nameserver)
  93 {
  94         struct addrinfo *ai;
  95         struct addrinfo hints;
  96         int             res;
  97         struct sockaddr *sa     = NULL;
  98
  99         memset(&hints, 0, sizeof(hints));
 100         hints.ai_flags = AI_NUMERICHOST;
 101
 102         res = getaddrinfo(nameserver, NULL, &hints, &ai);
 103         if (res == 0) {
 104                 if ((ai->ai_family == AF_INET) || (ai->ai_family == AF_INET6)) {
 105                         sa = malloc(ai->ai_addrlen);
 106                         memcpy(sa, ai->ai_addr, ai->ai_addrlen);
 107                 }
 108                 freeaddrinfo(ai);
 109         }
 110
 111         return sa;
 112 }
 113
 114
 115 /*
 116  * _dnsinfo_parse_nameserver
 117  *
 118  * Parse arguments to the nameserver token. This is essentially a getaddrinfo(3)
 119  * with AI_NUMERICHOST. However, if the conversion fails, check if the address
 120  * contains an optional trailing '.' followed by a numeric port number.  If found,
 121  * remove the port number and retry the conversion (e.g. 127.0.0.1.55 or ::1.55).
 122  */
 123 static struct sockaddr *
 124 _dnsinfo_parse_nameserver(char *token)
 125 {
 126         char            *dot;
 127         long            number;
 128         struct sockaddr *sa;
 129
 130         sa = _dnsinfo_parse_address(token);
 131         if (sa != NULL) {
 132                 return sa;
 133         }
 134
 135         // if we could not parse address, attempt to remove
 136         // an optional trailing port number
 137         dot = strrchr(token, '.');
 138         if (dot == NULL) {
 139                 return NULL;
 140         }
 141
 142         number = strtol(dot + 1, NULL, 10);
 143         if ((number < 0) || (number > UINT16_MAX)) {
 144                 return NULL;
 145         }
 146
 147         *dot = '\0';
 148         sa = _dnsinfo_parse_address(token);
 149         if (sa != NULL) {
 150                 in_port_t       port    = htons(number);
 151
 152                 switch (sa->sa_family) {
 153                         case AF_INET :
 154                                 /* ALIGN: cast ok, sockaddr was malloc'd */
 155                                 ((struct sockaddr_in *)(void *)sa)->sin_port = port;
 156                                 break;
 157                         case AF_INET6 :
 158                                 /* ALIGN: cast ok, sockaddr was malloc'd */
 159                                 ((struct sockaddr_in6 *)(void *)sa)->sin6_port = port;
 160                                 break;
 161                 }
 162         }
 163
 164         return sa;
 165 }
 166
 167
 168 /*
 169  * _dnsinfo_parse_sortaddr
 170  *
 171  * Parse arguments to the sortlist token.
 172  */
 173 static dns_sortaddr_t *
 174 _dnsinfo_parse_sortaddr(char *token)
 175 {
 176         struct in_addr          addr;
 177         struct in_addr          mask;
 178         struct sockaddr         *sa;
 179         char                    *slash;
 180         dns_sortaddr_t          *sortaddr       = NULL;
 181
 182         slash = strchr(token, '/');
 183         if (slash != NULL) {
 184                 *slash = '\0';
 185         }
 186
 187         sa = _dnsinfo_parse_address(token);
 188         if (sa == NULL) {
 189                 // if we could not parse the address
 190                 goto done;
 191         } else if (sa->sa_family != AF_INET) {
 192                 // if not AF_INET
 193                 goto done;
 194         } else {
 195                 /* ALIGN: cast ok, sockaddr was malloc'd */
 196                 addr = ((struct sockaddr_in *)(void *)sa)->sin_addr;
 197                 free(sa);
 198                 sa = NULL;
 199         }
 200
 201         if (slash != NULL) {
 202                 sa = _dnsinfo_parse_address(slash + 1);
 203                 if (sa == NULL) {
 204                         // if we could not parse the provided mask
 205                         goto done;
 206                 } else if (sa->sa_family != AF_INET) {
 207                         // if mask not AF_INET
 208                         goto done;
 209                 } else {
 210                         /* ALIGN: cast ok, sockaddr was malloc'd */
 211                         mask = ((struct sockaddr_in *)(void *)sa)->sin_addr;
 212                         free(sa);
 213                         sa = NULL;
 214                 }
 215         } else {
 216                 in_addr_t       a;
 217                 in_addr_t       m;
 218
 219                 a = ntohl(addr.s_addr);
 220                 if (IN_CLASSA(a)) {
 221                         m = IN_CLASSA_NET;
 222                 } else if (IN_CLASSB(a)) {
 223                         m = IN_CLASSB_NET;
 224                 } else if (IN_CLASSC(a)) {
 225                         m = IN_CLASSC_NET;
 226                 } else {
 227                         goto done;
 228                 }
 229
 230                 mask.s_addr = htonl(m);
 231         }
 232
 233         sortaddr = malloc(sizeof(*sortaddr));
 234         sortaddr->address = addr;
 235         sortaddr->mask    = mask;
 236
 237     done :
 238
 239         if (sa != NULL) free(sa);
 240         return sortaddr;
 241 }
 242
 243
 244 /*
 245  * _dnsinfo_flatfile_set_flags
 246  *
 247  * Set the default resolver flags.
 248  */
 249 __private_extern__
 250 void
 251 _dnsinfo_flatfile_set_flags(uint32_t flags)
 252 {
 253         _dnsinfo_flatfile_flags = flags;
 254         return;
 255 }
 256
 257
 258 static void
 259 _dnsinfo_flatfile_update_flags(dns_create_resolver_t *_resolver)
 260 {
 261         uint32_t                new_flags;
 262         uint32_t                old_flags;
 263         _dns_resolver_buf_t     *resolver       = (_dns_resolver_buf_t *)*_resolver;
 264
 265         old_flags = ntohl(resolver->resolver.flags);
 266         new_flags = old_flags | _dnsinfo_flatfile_flags;
 267         _dns_resolver_set_flags(_resolver, new_flags);
 268         return;
 269 }
 270
 271
 272 /*
 273  * _dnsinfo_flatfile_create_resolver
 274  *
 275  * Create a new dns resolver configuration from the configuration file at the
 276  * specified path. (e.g. /etc/resolv.conf or /etc/resolver/apple.com)
 277  */
 278 static dns_create_resolver_t
 279 _dnsinfo_flatfile_create_resolver(const char *dir, const char *path)
 280 {
 281         char                    *buf;
 282         uint32_t                config_flags            = 0;
 283         FILE                    *f;
 284         char                    filename[FILENAME_MAX];
 285         size_t                  len                     = 0;
 286         char                    *line                   = NULL;
 287         dns_create_resolver_t   res                     = NULL;
 288         const char              *sep                    = " \t";
 289         int                     token_count[TOKEN_MAX]  = { 0 };
 290
 291         filename[0] = 0;
 292         if (dir != NULL) {
 293                 strlcpy(filename, dir, sizeof(filename));
 294                 strlcat(filename, "/", sizeof(filename));
 295         }
 296         strlcat(filename, path, sizeof(filename));
 297
 298         f = fopen(filename, "r");
 299         if (f == NULL) return NULL;
 300
 301         while ((buf = fgetln(f, &len)) != NULL) {
 302                 char    *lineptr;
 303                 int     max_count;
 304                 int     token;
 305                 char    *word;
 306
 307                 if (len == 0) continue;
 308                 if (buf[len-1] == '\n') buf[len-1] = '\0';
 309
 310                 line = reallocf(line, len+1);
 311                 if (line == NULL) continue;
 312
 313                 strlcpy(line, buf, len+1);
 314
 315                 // parse the first word of the line (the config token)
 316                 lineptr = line;
 317                 word = strsep(&lineptr, sep);
 318                 if (word == NULL) {
 319                         // if empty line
 320                         continue;
 321                 }
 322                 if (word[0] == ';' || word[0] == '#') {
 323                         // if comment
 324                         continue;
 325                 }
 326
 327                 // translate config token to enumerated value
 328                 token = -1;
 329                 for (size_t i = 0; i < sizeof(tokens) / sizeof(tokens[0]); i++) {
 330                         if (strcasecmp(word, tokens[i].name) == 0) {
 331                                 token     = tokens[i].token;
 332                                 max_count = tokens[i].max_count;
 333                                 break;
 334                         }
 335                 }
 336                 if (token == -1) {
 337                         // if not a recognized token
 338                         SC_log(LOG_NOTICE,
 339                                "Unrecognized token (%s) found in: %s",
 340                                word,
 341                                filename);
 342                         continue;
 343                 }
 344
 345                 // parse the next word of the line (the config option)
 346                 word = strsep(&lineptr, sep);
 347                 if (word == NULL) {
 348                         // if no option
 349                         continue;
 350                 }
 351                 if (++token_count[token] > max_count) {
 352                         // if too many options
 353                         continue;
 354                 }
 355
 356                 // create resolver
 357                 if (res == NULL) {
 358                         res = _dns_resolver_create();
 359                         if (res == NULL) {
 360                                 // if we could not create a resolver
 361                                 goto done;
 362                         }
 363                 }
 364
 365                 switch (token) {
 366                         case TOKEN_DOMAIN: {
 367                                 size_t  len;
 368
 369                                 len = strlen(word);
 370                                 while ((len > 0) && (word[len - 1] == '.')) {
 371                                         // trim trailing '.'
 372                                         word[--len] = '\0';
 373                                 }
 374                                 if (len > 0) {
 375                                         _dns_resolver_set_domain(&res, word);
 376                                 }
 377                                 break;
 378                         }
 379
 380                         case TOKEN_FLAGS: {
 381                                 while (word != NULL) {
 382                                         if (word[0] != '\0') {
 383                                                 if (strcasecmp(word, "scoped") == 0) {
 384                                                         config_flags |= DNS_RESOLVER_FLAGS_SCOPED;
 385                                                 } else if (strcasecmp(word, "a") == 0) {
 386                                                         config_flags |= DNS_RESOLVER_FLAGS_REQUEST_A_RECORDS;
 387                                                 } else if (strcasecmp(word, "aaaa") == 0) {
 388                                                         config_flags |= DNS_RESOLVER_FLAGS_REQUEST_AAAA_RECORDS;
 389                                                 }
 390                                         }
 391                                         word = strsep(&lineptr, sep);
 392                                 }
 393                                 break;
 394                         }
 395
 396                         case TOKEN_INTERFACE: {
 397                                 unsigned int    if_index;
 398
 399                                 if_index = if_nametoindex(word);
 400                                 if (if_index > 0) {
 401                                         _dns_resolver_set_if_index(&res, if_index, word);
 402                                 }
 403                                 break;
 404                         }
 405
 406                         case TOKEN_NAMESERVER: {
 407                                 struct sockaddr *sa;
 408
 409                                 sa = _dnsinfo_parse_nameserver(word);
 410                                 if (sa != NULL) {
 411                                         _dns_resolver_add_nameserver(&res, sa);
 412                                         free(sa);
 413                                 }
 414                                 break;
 415                         }
 416
 417                         case TOKEN_OPTIONS: {
 418                                 char    *options        = NULL;
 419
 420                                 while (word != NULL) {
 421                                         if (word[0] != '\0') {
 422                                                 if (options == NULL) {
 423                                                         options = malloc(len+1);
 424                                                         if (options == NULL) break;
 425
 426                                                         strlcpy(options, word, len+1);
 427                                                 } else {
 428                                                         strlcat(options, " ", len+1);
 429                                                         strlcat(options, word, len+1);
 430                                                 }
 431                                         }
 432                                         word = strsep(&lineptr, sep);
 433                                 }
 434
 435                                 if (options != NULL) {
 436                                         _dns_resolver_set_options(&res, options);
 437                                         free(options);
 438                                 }
 439                                 break;
 440                         }
 441
 442                         case TOKEN_PORT: {
 443                                 long    number  = -1;
 444
 445                                 number = strtol(word, NULL, 0);
 446                                 if (number < 0 || number > UINT16_MAX) break;
 447                                 _dns_resolver_set_port(&res, number);
 448                                 break;
 449                         }
 450
 451                         case TOKEN_SEARCH: {
 452                                 int     n       = 0;
 453
 454                                 // multiple search domains are supported
 455                                 while ((word != NULL) && (n++ < MAXDNSRCH)) {
 456                                         size_t  len;
 457
 458                                         len = strlen(word);
 459                                         while ((len > 0) && (word[len - 1] == '.')) {
 460                                                 // trim trailing '.'
 461                                                 word[--len] = '\0';
 462                                         }
 463                                         if (len > 0) {
 464                                                 _dns_resolver_add_search(&res, word);
 465                                         }
 466                                         word = strsep(&lineptr, sep);
 467                                 }
 468                                 break;
 469                         }
 470
 471                         case TOKEN_SEARCH_ORDER: {
 472                                 long    number  = -1;
 473
 474                                 number = strtol(word, NULL, 0);
 475                                 if (number < 0 || number > (long)UINT32_MAX) break;
 476                                 _dns_resolver_set_order(&res, (uint32_t)number);
 477                                 break;
 478                         }
 479
 480                         case TOKEN_SORTLIST: {
 481                                 int     n       = 0;
 482
 483                                 while ((word != NULL) && (n++ < MAXRESOLVSORT)) {
 484                                         dns_sortaddr_t  *sortaddr;
 485
 486                                         sortaddr = _dnsinfo_parse_sortaddr(word);
 487                                         if (sortaddr == NULL) break;
 488                                         _dns_resolver_add_sortaddr(&res, sortaddr);
 489                                         free(sortaddr);
 490                                         word = strsep(&lineptr, sep);
 491                                 }
 492                                 break;
 493                         }
 494
 495                         case TOKEN_TIMEOUT: {
 496                                 long    number  = -1;
 497
 498                                 number = strtol(word, NULL, 0);
 499                                 if (number < 0 || number > (long)UINT32_MAX) break;
 500                                 _dns_resolver_set_timeout(&res, (uint32_t)number);
 501                                 break;
 502                         }
 503                 }
 504         }
 505
 506         // set the domain to the basename of the path if not specified
 507         if ((res != NULL) && (token_count[TOKEN_DOMAIN] == 0)) {
 508                 const char      *domain;
 509
 510                 domain = strrchr(path, '/');
 511                 if (domain == NULL) {
 512                         domain = path;
 513                 } else {
 514                         domain = domain + 1;
 515                 }
 516                 _dns_resolver_set_domain(&res, domain);
 517         }
 518
 519         if (res != NULL) {
 520                 // config flags should overwrite any default flags
 521                 if (config_flags != 0) {
 522                         _dns_resolver_set_flags(&res, config_flags);
 523                 } else {
 524                         _dnsinfo_flatfile_update_flags(&res);
 525                 }
 526         }
 527
 528     done :
 529
 530         if (line != NULL) free(line);
 531         fclose(f);
 532         return res;
 533 }
 534
 535
 536 /*
 537  * _dnsinfo_flatfile_add_resolvers
 538  *
 539  * Parse the files in the resolver config directory (/etc/resolver) and add each
 540  * resolver to the dns config.
 541  */
 542 __private_extern__
 543 void
 544 _dnsinfo_flatfile_add_resolvers(dns_create_config_t *config)
 545 {
 546         struct dirent           *de;
 547         DIR                     *dp;
 548         dns_create_resolver_t   res;
 549
 550         dp = opendir(_PATH_RESOLVER_DIR);
 551         if (dp == NULL) {
 552                 return;
 553         }
 554
 555         while ((de = readdir(dp)) != NULL) {
 556                 if (strcmp(de->d_name, ".") == 0 ||
 557                     strcmp(de->d_name, "..") == 0) continue;
 558
 559                 res = _dnsinfo_flatfile_create_resolver(_PATH_RESOLVER_DIR, de->d_name);
 560                 if (res != NULL) {
 561                         _dns_configuration_add_resolver(config, res);
 562                         _dns_resolver_free(&res);
 563                 }
 564         }
 565
 566         closedir(dp);
 567         return;
 568 }
 569
 570
 571 #ifdef  MAIN
 572 #undef  MAIN
 573
 574 #include "dnsinfo_logging.h"
 575 #include "dnsinfo_copy.c"
 576
 577 int
 578 main(int argc, char **argv)
 579 {
 580         dns_config_t            *dns_config     = NULL;
 581         _dns_config_buf_t       *dns_config_buf = NULL;
 582         dns_create_config_t     dns_create_config;
 583         dns_create_resolver_t   dns_create_resolver;
 584
 585         dns_create_resolver = _dnsinfo_flatfile_create_resolver(NULL, _PATH_RESCONF);
 586         _dns_resolver_free(&dns_create_resolver);
 587
 588         dns_create_config = _dns_configuration_create();
 589         if (dns_create_config != NULL) {
 590                 size_t          n;
 591
 592                 _dnsinfo_flatfile_add_resolvers(&dns_create_config);
 593
 594                 n = sizeof(_dns_config_buf_t);
 595                 n += ntohl(((_dns_config_buf_t *)dns_create_config)->n_attribute);
 596                 dns_config_buf = _dns_configuration_buffer_create((void *)dns_create_config, n);
 597                 _dns_configuration_free(&dns_create_config);
 598         }
 599
 600         if (dns_config_buf != NULL) {
 601                 dns_config = _dns_configuration_buffer_expand(dns_config_buf);
 602                 if (dns_config == NULL) {
 603                         // if we were unable to expand the configuration
 604                         _dns_configuration_buffer_free(&dns_config_buf);
 605                 }
 606         }
 607
 608         if (dns_config != NULL) {
 609                 _dns_configuration_log(dns_config, TRUE, NULL);
 610                 free(dns_config);
 611         }
 612
 613         return 0;
 614 }
 615
 616 #endif