src/resolv_wrapper.c

   1 /*
   2  * Copyright (c) 2014      Andreas Schneider <asn@samba.org>
   3  * Copyright (c) 2014      Jakub Hrozek <jakub.hrozek@posteo.se>
   4  *
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  *
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * 3. Neither the name of the author nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include "config.h"
  36
  37 #include <errno.h>
  38 #include <arpa/inet.h>
  39 #ifdef HAVE_ARPA_NAMESER_H
  40 #include <arpa/nameser.h>
  41 #endif /* HAVE_ARPA_NAMESER_H */
  42 #include <netinet/in.h>
  43 #include <sys/socket.h>
  44 #include <sys/types.h>
  45 #include <stdarg.h>
  46 #include <stdlib.h>
  47 #include <stdio.h>
  48 #include <stdbool.h>
  49 #include <string.h>
  50 #include <unistd.h>
  51 #include <ctype.h>
  52
  53 #include <resolv.h>
  54
  55 /* GCC has printf type attribute check. */
  56 #ifdef HAVE_ATTRIBUTE_PRINTF_FORMAT
  57 #define PRINTF_ATTRIBUTE(a,b) __attribute__ ((__format__ (__printf__, a, b)))
  58 #else
  59 #define PRINTF_ATTRIBUTE(a,b)
  60 #endif /* HAVE_ATTRIBUTE_PRINTF_FORMAT */
  61
  62 #ifdef HAVE_DESTRUCTOR_ATTRIBUTE
  63 #define DESTRUCTOR_ATTRIBUTE __attribute__ ((destructor))
  64 #else
  65 #define DESTRUCTOR_ATTRIBUTE
  66 #endif /* HAVE_DESTRUCTOR_ATTRIBUTE */
  67
  68 #ifndef RWRAP_DEFAULT_FAKE_TTL
  69 #define RWRAP_DEFAULT_FAKE_TTL 600
  70 #endif  /* RWRAP_DEFAULT_FAKE_TTL */
  71
  72 #ifndef HAVE_NS_NAME_COMPRESS
  73 #define ns_name_compress dn_comp
  74 #endif
  75
  76 #define ns_t_uri 256
  77
  78 enum rwrap_dbglvl_e {
  79         RWRAP_LOG_ERROR = 0,
  80         RWRAP_LOG_WARN,
  81         RWRAP_LOG_DEBUG,
  82         RWRAP_LOG_TRACE
  83 };
  84
  85 #ifdef NDEBUG
  86 # define RWRAP_LOG(...)
  87 #else /* NDEBUG */
  88
  89 static void rwrap_log(enum rwrap_dbglvl_e dbglvl, const char *func, const char *format, ...) PRINTF_ATTRIBUTE(3, 4);
  90 # define RWRAP_LOG(dbglvl, ...) rwrap_log((dbglvl), __func__, __VA_ARGS__)
  91
  92 static void rwrap_log(enum rwrap_dbglvl_e dbglvl,
  93                       const char *func,
  94                       const char *format, ...)
  95 {
  96         char buffer[1024];
  97         va_list va;
  98         const char *d;
  99         unsigned int lvl = 0;
 100         int pid = getpid();
 101
 102         d = getenv("RESOLV_WRAPPER_DEBUGLEVEL");
 103         if (d != NULL) {
 104                 lvl = atoi(d);
 105         }
 106
 107         va_start(va, format);
 108         vsnprintf(buffer, sizeof(buffer), format, va);
 109         va_end(va);
 110
 111         if (lvl >= dbglvl) {
 112                 switch (dbglvl) {
 113                         case RWRAP_LOG_ERROR:
 114                                 fprintf(stderr,
 115                                         "RWRAP_ERROR(%d) - %s: %s\n",
 116                                         pid, func, buffer);
 117                                 break;
 118                         case RWRAP_LOG_WARN:
 119                                 fprintf(stderr,
 120                                         "RWRAP_WARN(%d) - %s: %s\n",
 121                                         pid, func, buffer);
 122                                 break;
 123                         case RWRAP_LOG_DEBUG:
 124                                 fprintf(stderr,
 125                                         "RWRAP_DEBUG(%d) - %s: %s\n",
 126                                         pid, func, buffer);
 127                                 break;
 128                         case RWRAP_LOG_TRACE:
 129                                 fprintf(stderr,
 130                                         "RWRAP_TRACE(%d) - %s: %s\n",
 131                                         pid, func, buffer);
 132                                 break;
 133                 }
 134         }
 135 }
 136 #endif /* NDEBUG RWRAP_LOG */
 137
 138 #ifndef SAFE_FREE
 139 #define SAFE_FREE(x) do { if ((x) != NULL) {free(x); (x)=NULL;} } while(0)
 140 #endif
 141
 142 #define NEXT_KEY(buf, key) do {                                 \
 143         (key) = (buf) ? strpbrk((buf), " \t") : NULL;           \
 144         if ((key) != NULL) {                                    \
 145                 (key)[0] = '\0';                                \
 146                 (key)++;                                        \
 147         }                                                       \
 148         while ((key) != NULL                                    \
 149                && (isblank((int)(key)[0]))) {                   \
 150                 (key)++;                                        \
 151         }                                                       \
 152 } while(0);
 153
 154 #define RWRAP_MAX_RECURSION 64
 155
 156 /* Priority and weight can be omitted from the hosts file, but need to be part
 157  * of the output
 158  */
 159 #define DFL_SRV_PRIO    1
 160 #define DFL_SRV_WEIGHT  100
 161 #define DFL_URI_PRIO    1
 162 #define DFL_URI_WEIGHT  100
 163
 164 struct rwrap_srv_rrdata {
 165         uint16_t port;
 166         uint16_t prio;
 167         uint16_t weight;
 168         char hostname[MAXDNAME];
 169 };
 170
 171 struct rwrap_uri_rrdata {
 172         uint16_t prio;
 173         uint16_t weight;
 174         char uri[MAXDNAME];
 175 };
 176
 177 struct rwrap_soa_rrdata {
 178         uint32_t serial;
 179         uint32_t refresh;
 180         uint32_t retry;
 181         uint32_t expire;
 182         uint32_t minimum;
 183         char nameserver[MAXDNAME];
 184         char mailbox[MAXDNAME];
 185 };
 186
 187 struct rwrap_fake_rr {
 188         union fake_rrdata {
 189                 struct in_addr a_rec;
 190                 struct in6_addr aaaa_rec;
 191                 struct rwrap_srv_rrdata srv_rec;
 192                 struct rwrap_uri_rrdata uri_rec;
 193                 struct rwrap_soa_rrdata soa_rec;
 194                 char cname_rec[MAXDNAME];
 195                 char ptr_rec[MAXDNAME];
 196         } rrdata;
 197
 198         char key[MAXDNAME];
 199         int type; /* ns_t_* */
 200 };
 201
 202 static void rwrap_fake_rr_init(struct rwrap_fake_rr *rr, size_t len)
 203 {
 204         size_t i;
 205
 206         for (i = 0; i < len; i++) {
 207                 rr[i].type = ns_t_invalid;
 208         }
 209 }
 210
 211 static int rwrap_create_fake_a_rr(const char *key,
 212                                   const char *value,
 213                                   struct rwrap_fake_rr *rr)
 214 {
 215         int ok;
 216
 217         ok = inet_pton(AF_INET, value, &rr->rrdata.a_rec);
 218         if (!ok) {
 219                 RWRAP_LOG(RWRAP_LOG_ERROR,
 220                           "Failed to convert [%s] to binary\n", value);
 221                 return -1;
 222         }
 223
 224         memcpy(rr->key, key, strlen(key) + 1);
 225         rr->type = ns_t_a;
 226         return 0;
 227 }
 228
 229 static int rwrap_create_fake_aaaa_rr(const char *key,
 230                                      const char *value,
 231                                      struct rwrap_fake_rr *rr)
 232 {
 233         int ok;
 234
 235         ok = inet_pton(AF_INET6, value, &rr->rrdata.aaaa_rec);
 236         if (!ok) {
 237                 RWRAP_LOG(RWRAP_LOG_ERROR,
 238                           "Failed to convert [%s] to binary\n", value);
 239                 return -1;
 240         }
 241
 242         memcpy(rr->key, key, strlen(key) + 1);
 243         rr->type = ns_t_aaaa;
 244         return 0;
 245 }
 246 static int rwrap_create_fake_ns_rr(const char *key,
 247                                    const char *value,
 248                                    struct rwrap_fake_rr *rr)
 249 {
 250         memcpy(rr->rrdata.srv_rec.hostname, value, strlen(value) + 1);
 251         memcpy(rr->key, key, strlen(key) + 1);
 252         rr->type = ns_t_ns;
 253         return 0;
 254 }
 255
 256 static int rwrap_create_fake_srv_rr(const char *key,
 257                                     const char *value,
 258                                     struct rwrap_fake_rr *rr)
 259 {
 260         char *str_prio;
 261         char *str_weight;
 262         char *str_port;
 263         const char *hostname;
 264
 265         /* parse the value into priority, weight, port and hostname
 266          * and check the validity */
 267         hostname = value;
 268         NEXT_KEY(hostname, str_port);
 269         NEXT_KEY(str_port, str_prio);
 270         NEXT_KEY(str_prio, str_weight);
 271         if (str_port == NULL || hostname == NULL) {
 272                 RWRAP_LOG(RWRAP_LOG_ERROR,
 273                           "Malformed SRV entry [%s]\n", value);
 274                 return -1;
 275         }
 276
 277         if (str_prio) {
 278                 rr->rrdata.srv_rec.prio = atoi(str_prio);
 279         } else {
 280                 rr->rrdata.srv_rec.prio = DFL_SRV_PRIO;
 281         }
 282         if (str_weight) {
 283                 rr->rrdata.srv_rec.weight = atoi(str_weight);
 284         } else {
 285                 rr->rrdata.srv_rec.weight = DFL_SRV_WEIGHT;
 286         }
 287         rr->rrdata.srv_rec.port = atoi(str_port);
 288         memcpy(rr->rrdata.srv_rec.hostname , hostname, strlen(hostname) + 1);
 289
 290         memcpy(rr->key, key, strlen(key) + 1);
 291         rr->type = ns_t_srv;
 292         return 0;
 293 }
 294
 295 static int rwrap_create_fake_uri_rr(const char *key,
 296                                     const char *value,
 297                                     struct rwrap_fake_rr *rr)
 298 {
 299         char *str_prio;
 300         char *str_weight;
 301         const char *uri;
 302
 303         /* parse the value into priority, weight, and uri
 304          * and check the validity */
 305         uri = value;
 306         NEXT_KEY(uri, str_prio);
 307         NEXT_KEY(str_prio, str_weight);
 308         if (uri == NULL) {
 309                 RWRAP_LOG(RWRAP_LOG_ERROR,
 310                           "Malformed URI entry [%s]\n", value);
 311                 return -1;
 312         }
 313
 314         if (str_prio) {
 315                 rr->rrdata.uri_rec.prio = atoi(str_prio);
 316         } else {
 317                 rr->rrdata.uri_rec.prio = DFL_URI_PRIO;
 318         }
 319         if (str_weight) {
 320                 rr->rrdata.uri_rec.weight = atoi(str_weight);
 321         } else {
 322                 rr->rrdata.uri_rec.weight = DFL_URI_WEIGHT;
 323         }
 324         memcpy(rr->rrdata.uri_rec.uri, uri, strlen(uri) + 1);
 325
 326         memcpy(rr->key, key, strlen(key) + 1);
 327         rr->type = ns_t_uri;
 328         return 0;
 329 }
 330
 331 static int rwrap_create_fake_soa_rr(const char *key,
 332                                     const char *value,
 333                                     struct rwrap_fake_rr *rr)
 334 {
 335         const char *nameserver;
 336         char *mailbox;
 337         char *str_serial;
 338         char *str_refresh;
 339         char *str_retry;
 340         char *str_expire;
 341         char *str_minimum;
 342
 343         /* parse the value into nameserver, mailbox, serial, refresh,
 344          * retry, expire, minimum and check the validity
 345          */
 346         nameserver = value;
 347         NEXT_KEY(nameserver, mailbox);
 348         NEXT_KEY(mailbox, str_serial);
 349         NEXT_KEY(str_serial, str_refresh);
 350         NEXT_KEY(str_refresh, str_retry);
 351         NEXT_KEY(str_retry, str_expire);
 352         NEXT_KEY(str_expire, str_minimum);
 353         if (nameserver == NULL || mailbox == NULL || str_serial == NULL ||
 354             str_refresh == NULL || str_retry == NULL || str_expire == NULL ||
 355             str_minimum == NULL) {
 356                 RWRAP_LOG(RWRAP_LOG_ERROR,
 357                           "Malformed SOA entry [%s]\n", value);
 358                 return -1;
 359         }
 360
 361         memcpy(rr->rrdata.soa_rec.nameserver, nameserver, strlen(nameserver)+1);
 362         memcpy(rr->rrdata.soa_rec.mailbox, mailbox, strlen(mailbox)+1);
 363
 364         rr->rrdata.soa_rec.serial = atoi(str_serial);
 365         rr->rrdata.soa_rec.refresh = atoi(str_refresh);
 366         rr->rrdata.soa_rec.retry = atoi(str_retry);
 367         rr->rrdata.soa_rec.expire = atoi(str_expire);
 368         rr->rrdata.soa_rec.minimum = atoi(str_minimum);
 369
 370         memcpy(rr->key, key, strlen(key) + 1);
 371         rr->type = ns_t_soa;
 372         return 0;
 373 }
 374
 375 static int rwrap_create_fake_cname_rr(const char *key,
 376                                       const char *value,
 377                                       struct rwrap_fake_rr *rr)
 378 {
 379         memcpy(rr->rrdata.cname_rec , value, strlen(value) + 1);
 380         memcpy(rr->key, key, strlen(key) + 1);
 381         rr->type = ns_t_cname;
 382         return 0;
 383 }
 384
 385 static int rwrap_create_fake_ptr_rr(const char *key,
 386                                     const char *value,
 387                                     struct rwrap_fake_rr *rr)
 388 {
 389         memcpy(rr->rrdata.ptr_rec , value, strlen(value) + 1);
 390         memcpy(rr->key, key, strlen(key) + 1);
 391         rr->type = ns_t_ptr;
 392         return 0;
 393 }
 394
 395 /* Prepares a fake header with a single response. Advances header_blob */
 396 static ssize_t rwrap_fake_header(uint8_t **header_blob, size_t remaining,
 397                                  size_t ancount, size_t arcount)
 398 {
 399         uint8_t *hb;
 400         HEADER *h;
 401
 402         if (remaining < NS_HFIXEDSZ) {
 403                 RWRAP_LOG(RWRAP_LOG_ERROR, "Buffer too small!\n");
 404                 return -1;
 405         }
 406
 407         hb = *header_blob;
 408         memset(hb, 0, NS_HFIXEDSZ);
 409
 410         h = (HEADER *) hb;
 411         h->id = res_randomid();         /* random query ID */
 412         h->qr = 1;                      /* response flag */
 413         h->rd = 1;                      /* recursion desired */
 414         h->ra = 1;                      /* recursion available */
 415
 416         h->qdcount = htons(1);          /* no. of questions */
 417         h->ancount = htons(ancount);    /* no. of answers */
 418         h->arcount = htons(arcount);    /* no. of add'tl records */
 419
 420         hb += NS_HFIXEDSZ;              /* move past the header */
 421         *header_blob = hb;
 422
 423         return NS_HFIXEDSZ;
 424 }
 425
 426 static ssize_t rwrap_fake_question(const char *question,
 427                                    uint16_t type,
 428                                    uint8_t **question_ptr,
 429                                    size_t remaining)
 430 {
 431         uint8_t *qb = *question_ptr;
 432         int n;
 433
 434         n = ns_name_compress(question, qb, remaining, NULL, NULL);
 435         if (n < 0) {
 436                 RWRAP_LOG(RWRAP_LOG_ERROR,
 437                           "Failed to compress [%s]\n", question);
 438                 return -1;
 439         }
 440
 441         qb += n;
 442         remaining -= n;
 443
 444         if (remaining < 2 * sizeof(uint16_t)) {
 445                 RWRAP_LOG(RWRAP_LOG_ERROR, "Buffer too small!\n");
 446                 return -1;
 447         }
 448
 449         NS_PUT16(type, qb);
 450         NS_PUT16(ns_c_in, qb);
 451
 452         *question_ptr = qb;
 453         return n + 2 * sizeof(uint16_t);
 454 }
 455
 456 static ssize_t rwrap_fake_rdata_common(uint16_t type,
 457                                        size_t rdata_size,
 458                                        const char *key,
 459                                        size_t remaining,
 460                                        uint8_t **rdata_ptr)
 461 {
 462         uint8_t *rd = *rdata_ptr;
 463         ssize_t written = 0;
 464
 465         written = ns_name_compress(key, rd, remaining, NULL, NULL);
 466         if (written < 0) {
 467                 RWRAP_LOG(RWRAP_LOG_ERROR,
 468                           "Failed to compress [%s]\n", key);
 469                 return -1;
 470         }
 471         rd += written;
 472         remaining -= written;
 473
 474         if (remaining < 3 * sizeof(uint16_t) + sizeof(uint32_t)) {
 475                 RWRAP_LOG(RWRAP_LOG_ERROR, "Buffer too small\n");
 476                 return -1;
 477         }
 478
 479         NS_PUT16(type, rd);
 480         NS_PUT16(ns_c_in, rd);
 481         NS_PUT32(RWRAP_DEFAULT_FAKE_TTL, rd);
 482         NS_PUT16(rdata_size, rd);
 483
 484         if (remaining < rdata_size) {
 485                 RWRAP_LOG(RWRAP_LOG_ERROR, "Buffer too small\n");
 486                 return -1;
 487         }
 488
 489         *rdata_ptr = rd;
 490         return written + 3 * sizeof(uint16_t) + sizeof(uint32_t) + rdata_size;
 491 }
 492
 493 static ssize_t rwrap_fake_a(struct rwrap_fake_rr *rr,
 494                             uint8_t *answer_ptr,
 495                             size_t anslen)
 496 {
 497         uint8_t *a = answer_ptr;
 498         ssize_t resp_size;
 499
 500         if (rr->type != ns_t_a) {
 501                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 502                 return -1;
 503         }
 504         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding A RR");
 505
 506         resp_size = rwrap_fake_rdata_common(ns_t_a, sizeof(struct in_addr), rr->key,
 507                                             anslen, &a);
 508         if (resp_size < 0) {
 509                 return -1;
 510         }
 511
 512         memcpy(a, &rr->rrdata.a_rec, sizeof(struct in_addr));
 513
 514         return resp_size;
 515 }
 516
 517 static ssize_t rwrap_fake_aaaa(struct rwrap_fake_rr *rr,
 518                                uint8_t *answer,
 519                                size_t anslen)
 520 {
 521         uint8_t *a = answer;
 522         ssize_t resp_size;
 523
 524         if (rr->type != ns_t_aaaa) {
 525                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 526                 return -1;
 527         }
 528         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding AAAA RR");
 529
 530         resp_size = rwrap_fake_rdata_common(ns_t_aaaa, sizeof(struct in6_addr),
 531                                             rr->key, anslen, &a);
 532         if (resp_size < 0) {
 533                 return -1;
 534         }
 535
 536         memcpy(a, &rr->rrdata.aaaa_rec, sizeof(struct in6_addr));
 537
 538         return resp_size;
 539 }
 540
 541 static ssize_t rwrap_fake_ns(struct rwrap_fake_rr *rr,
 542                              uint8_t *answer,
 543                             size_t anslen)
 544 {
 545         uint8_t *a = answer;
 546         ssize_t resp_size = 0;
 547         size_t rdata_size;
 548         unsigned char hostname_compressed[MAXDNAME];
 549         ssize_t compressed_len;
 550
 551         if (rr->type != ns_t_ns) {
 552                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 553                 return -1;
 554         }
 555         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding NS RR");
 556
 557         /* Prepare the data to write */
 558         compressed_len = ns_name_compress(rr->rrdata.srv_rec.hostname,
 559                                           hostname_compressed,
 560                                           MAXDNAME,
 561                                           NULL,
 562                                           NULL);
 563         if (compressed_len < 0) {
 564                 return -1;
 565         }
 566
 567         /* Is this enough? */
 568         rdata_size = compressed_len;
 569
 570         resp_size = rwrap_fake_rdata_common(ns_t_ns, rdata_size,
 571                                             rr->key, anslen, &a);
 572         if (resp_size < 0) {
 573                 return -1;
 574         }
 575
 576         memcpy(a, hostname_compressed, compressed_len);
 577
 578         return resp_size;
 579 }
 580
 581 static ssize_t rwrap_fake_srv(struct rwrap_fake_rr *rr,
 582                               uint8_t *answer,
 583                               size_t anslen)
 584 {
 585         uint8_t *a = answer;
 586         ssize_t resp_size;
 587         size_t rdata_size;
 588         unsigned char hostname_compressed[MAXDNAME];
 589         ssize_t compressed_len;
 590
 591         if (rr->type != ns_t_srv) {
 592                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 593                 return -1;
 594         }
 595         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding SRV RR");
 596         rdata_size = 3 * sizeof(uint16_t);
 597
 598         /* Prepare the data to write */
 599         compressed_len = ns_name_compress(rr->rrdata.srv_rec.hostname,
 600                                           hostname_compressed, MAXDNAME,
 601                                           NULL, NULL);
 602         if (compressed_len < 0) {
 603                 return -1;
 604         }
 605         rdata_size += compressed_len;
 606
 607         resp_size = rwrap_fake_rdata_common(ns_t_srv, rdata_size,
 608                                             rr->key, anslen, &a);
 609         if (resp_size < 0) {
 610                 return -1;
 611         }
 612
 613         NS_PUT16(rr->rrdata.srv_rec.prio, a);
 614         NS_PUT16(rr->rrdata.srv_rec.weight, a);
 615         NS_PUT16(rr->rrdata.srv_rec.port, a);
 616         memcpy(a, hostname_compressed, compressed_len);
 617
 618         return resp_size;
 619 }
 620
 621 static ssize_t rwrap_fake_uri(struct rwrap_fake_rr *rr,
 622                               uint8_t *answer,
 623                               size_t anslen)
 624 {
 625         uint8_t *a = answer;
 626         ssize_t resp_size;
 627         size_t rdata_size;
 628         size_t uri_len;
 629
 630         if (rr->type != ns_t_uri) {
 631                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 632                 return -1;
 633         }
 634         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding URI RR");
 635         rdata_size = 3 * sizeof(uint16_t);
 636         uri_len = strlen(rr->rrdata.uri_rec.uri) + 1;
 637         rdata_size += uri_len;
 638
 639         resp_size = rwrap_fake_rdata_common(ns_t_uri, rdata_size,
 640                                             rr->key, anslen, &a);
 641         if (resp_size < 0) {
 642                 return -1;
 643         }
 644
 645         NS_PUT16(rr->rrdata.uri_rec.prio, a);
 646         NS_PUT16(rr->rrdata.uri_rec.weight, a);
 647         memcpy(a, rr->rrdata.uri_rec.uri, uri_len);
 648
 649         return resp_size;
 650 }
 651
 652 static ssize_t rwrap_fake_soa(struct rwrap_fake_rr *rr,
 653                               uint8_t *answer,
 654                               size_t anslen)
 655 {
 656         uint8_t *a = answer;
 657         ssize_t resp_size;
 658         size_t rdata_size;
 659         unsigned char nameser_compressed[MAXDNAME];
 660         ssize_t compressed_ns_len;
 661         unsigned char mailbox_compressed[MAXDNAME];
 662         ssize_t compressed_mb_len;
 663
 664         if (rr->type != ns_t_soa) {
 665                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 666                 return -1;
 667         }
 668         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding SOA RR");
 669         rdata_size = 5 * sizeof(uint16_t);
 670
 671         compressed_ns_len = ns_name_compress(rr->rrdata.soa_rec.nameserver,
 672                                              nameser_compressed,
 673                                              MAXDNAME, NULL, NULL);
 674         if (compressed_ns_len < 0) {
 675                 return -1;
 676         }
 677         rdata_size += compressed_ns_len;
 678
 679         compressed_mb_len = ns_name_compress(rr->rrdata.soa_rec.mailbox,
 680                                              mailbox_compressed,
 681                                              MAXDNAME, NULL, NULL);
 682         if (compressed_mb_len < 0) {
 683                 return -1;
 684         }
 685         rdata_size += compressed_mb_len;
 686
 687         resp_size = rwrap_fake_rdata_common(ns_t_soa, rdata_size,
 688                                             rr->key, anslen, &a);
 689         if (resp_size < 0) {
 690                 return -1;
 691         }
 692
 693         memcpy(a, nameser_compressed, compressed_ns_len);
 694         a += compressed_ns_len;
 695         memcpy(a, mailbox_compressed, compressed_mb_len);
 696         a += compressed_mb_len;
 697         NS_PUT32(rr->rrdata.soa_rec.serial, a);
 698         NS_PUT32(rr->rrdata.soa_rec.refresh, a);
 699         NS_PUT32(rr->rrdata.soa_rec.retry, a);
 700         NS_PUT32(rr->rrdata.soa_rec.expire, a);
 701         NS_PUT32(rr->rrdata.soa_rec.minimum, a);
 702
 703         return resp_size;
 704 }
 705
 706 static ssize_t rwrap_fake_cname(struct rwrap_fake_rr *rr,
 707                                 uint8_t *answer,
 708                                 size_t anslen)
 709 {
 710         uint8_t *a = answer;
 711         ssize_t resp_size;
 712         unsigned char hostname_compressed[MAXDNAME];
 713         ssize_t rdata_size;
 714
 715         if (rr->type != ns_t_cname) {
 716                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 717                 return -1;
 718         }
 719         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding CNAME RR");
 720
 721         /* Prepare the data to write */
 722         rdata_size = ns_name_compress(rr->rrdata.cname_rec,
 723                                       hostname_compressed, MAXDNAME,
 724                                       NULL, NULL);
 725         if (rdata_size < 0) {
 726                 return -1;
 727         }
 728
 729         resp_size = rwrap_fake_rdata_common(ns_t_cname, rdata_size,
 730                                             rr->key, anslen, &a);
 731         if (resp_size < 0) {
 732                 return -1;
 733         }
 734
 735         memcpy(a, hostname_compressed, rdata_size);
 736
 737         return resp_size;
 738 }
 739
 740 static ssize_t rwrap_fake_ptr(struct rwrap_fake_rr *rr,
 741                               uint8_t *answer,
 742                               size_t anslen)
 743 {
 744         uint8_t *a = answer;
 745         ssize_t rdata_size;
 746         ssize_t resp_size;
 747         unsigned char hostname_compressed[MAXDNAME];
 748
 749         if (rr->type != ns_t_ptr) {
 750                 RWRAP_LOG(RWRAP_LOG_ERROR, "Wrong type!\n");
 751                 return -1;
 752         }
 753         RWRAP_LOG(RWRAP_LOG_TRACE, "Adding PTR RR");
 754
 755         /* Prepare the data to write */
 756         rdata_size = ns_name_compress(rr->rrdata.ptr_rec,
 757                                       hostname_compressed, MAXDNAME,
 758                                       NULL, NULL);
 759         if (rdata_size < 0) {
 760                 return -1;
 761         }
 762
 763         resp_size = rwrap_fake_rdata_common(ns_t_ptr, rdata_size,
 764                                             rr->key, anslen, &a);
 765         if (resp_size < 0) {
 766                 return -1;
 767         }
 768
 769         memcpy(a, hostname_compressed, rdata_size);
 770
 771         return resp_size;
 772 }
 773
 774 #define RESOLV_MATCH(line, name) \
 775         (strncmp(line, name, sizeof(name) - 1) == 0 && \
 776         (line[sizeof(name) - 1] == ' ' || \
 777          line[sizeof(name) - 1] == '\t'))
 778
 779 #define TYPE_MATCH(type, ns_type, rec_type, str_type, key, query) \
 780         ((type) == (ns_type) && \
 781          (strncmp((rec_type), (str_type), sizeof(str_type)) == 0) && \
 782          (strcasecmp(key, query)) == 0)
 783
 784
 785 static int rwrap_get_record(const char *hostfile, unsigned recursion,
 786                             const char *query, int type,
 787                             struct rwrap_fake_rr *rr);
 788
 789 static int rwrap_uri_recurse(const char *hostfile, unsigned recursion,
 790                              const char *query, struct rwrap_fake_rr *rr)
 791 {
 792         int rc;
 793
 794         rc = rwrap_get_record(hostfile, recursion, query, ns_t_uri, rr);
 795         if (rc == ENOENT) {
 796                 rc = 0;
 797         }
 798
 799         return rc;
 800 }
 801
 802 static int rwrap_srv_recurse(const char *hostfile, unsigned recursion,
 803                              const char *query, struct rwrap_fake_rr *rr)
 804 {
 805         int rc;
 806
 807         rc = rwrap_get_record(hostfile, recursion, query, ns_t_a, rr);
 808         if (rc == 0) return 0;
 809
 810         rc = rwrap_get_record(hostfile, recursion, query, ns_t_aaaa, rr);
 811         if (rc == ENOENT) rc = 0;
 812
 813         return rc;
 814 }
 815
 816 static int rwrap_cname_recurse(const char *hostfile, unsigned recursion,
 817                                const char *query, struct rwrap_fake_rr *rr)
 818 {
 819         int rc;
 820
 821         rc = rwrap_get_record(hostfile, recursion, query, ns_t_a, rr);
 822         if (rc == 0) return 0;
 823
 824         rc = rwrap_get_record(hostfile, recursion, query, ns_t_aaaa, rr);
 825         if (rc == 0) return 0;
 826
 827         rc = rwrap_get_record(hostfile, recursion, query, ns_t_cname, rr);
 828         if (rc == ENOENT) rc = 0;
 829
 830         return rc;
 831 }
 832
 833 static int rwrap_get_record(const char *hostfile, unsigned recursion,
 834                             const char *query, int type,
 835                             struct rwrap_fake_rr *rr)
 836 {
 837         FILE *fp = NULL;
 838         char buf[BUFSIZ];
 839         char *key = NULL;
 840         char *value = NULL;
 841         int rc = ENOENT;
 842         unsigned num_uris = 0;
 843
 844         if (recursion >= RWRAP_MAX_RECURSION) {
 845                 RWRAP_LOG(RWRAP_LOG_ERROR, "Recursed too deep!\n");
 846                 return -1;
 847         }
 848
 849         RWRAP_LOG(RWRAP_LOG_TRACE,
 850                   "Searching in fake hosts file %s for %s:%d\n", hostfile,
 851                   query, type);
 852
 853         fp = fopen(hostfile, "r");
 854         if (fp == NULL) {
 855                 RWRAP_LOG(RWRAP_LOG_ERROR,
 856                           "Opening %s failed: %s",
 857                           hostfile, strerror(errno));
 858                 return -1;
 859         }
 860
 861         while (fgets(buf, sizeof(buf), fp) != NULL) {
 862                 char *rec_type;
 863                 char *q;
 864
 865                 rec_type = buf;
 866                 key = value = NULL;
 867
 868                 NEXT_KEY(rec_type, key);
 869                 NEXT_KEY(key, value);
 870
 871                 if (key == NULL || value == NULL) {
 872                         RWRAP_LOG(RWRAP_LOG_WARN,
 873                                 "Malformed line: not enough parts, use \"rec_type key data\n"
 874                                 "For example \"A cwrap.org 10.10.10.10\"");
 875                         continue;
 876                 }
 877
 878                 q = value;
 879                 while(q[0] != '\n' && q[0] != '\0') {
 880                         q++;
 881                 }
 882                 q[0] = '\0';
 883
 884                 if (type == ns_t_uri && recursion > 0) {
 885                         /* Skip non-URI records. */
 886                         if (!TYPE_MATCH(type, ns_t_uri, rec_type, "URI", key, query)) {
 887                                 continue;
 888                         }
 889                         /* Skip previous records based on the recurse depth. */
 890                         num_uris++;
 891                         if (num_uris <= recursion) {
 892                                 continue;
 893                         }
 894                 }
 895
 896                 if (TYPE_MATCH(type, ns_t_a, rec_type, "A", key, query)) {
 897                         rc = rwrap_create_fake_a_rr(key, value, rr);
 898                         break;
 899                 } else if (TYPE_MATCH(type, ns_t_aaaa,
 900                                       rec_type, "AAAA", key, query)) {
 901                         rc = rwrap_create_fake_aaaa_rr(key, value, rr);
 902                         break;
 903                 } else if (TYPE_MATCH(type, ns_t_ns,
 904                                       rec_type, "NS", key, query)) {
 905                         rc = rwrap_create_fake_ns_rr(key, value, rr);
 906                         break;
 907                 } else if (TYPE_MATCH(type, ns_t_srv,
 908                                       rec_type, "SRV", key, query)) {
 909                         rc = rwrap_create_fake_srv_rr(key, value, rr);
 910                         if (rc == 0) {
 911                                 rc = rwrap_srv_recurse(hostfile, recursion+1,
 912                                                 rr->rrdata.srv_rec.hostname,
 913                                                 rr + 1);
 914                         }
 915                         break;
 916                 } else if (TYPE_MATCH(type, ns_t_uri,
 917                                       rec_type, "URI", key, query)) {
 918                         rc = rwrap_create_fake_uri_rr(key, value, rr);
 919                         if (rc == 0) {
 920                                 /* Recurse to collect multiple URI answers under a single key. */
 921                                 rc = rwrap_uri_recurse(hostfile, recursion + 1, key, rr + 1);
 922                         }
 923                         break;
 924                 } else if (TYPE_MATCH(type, ns_t_soa,
 925                                       rec_type, "SOA", key, query)) {
 926                         rc = rwrap_create_fake_soa_rr(key, value, rr);
 927                         break;
 928                 } else if (TYPE_MATCH(type, ns_t_cname,
 929                                       rec_type, "CNAME", key, query)) {
 930                         rc = rwrap_create_fake_cname_rr(key, value, rr);
 931                         if (rc == 0) {
 932                                 rc = rwrap_cname_recurse(hostfile, recursion+1,
 933                                                          value, rr + 1);
 934                         }
 935                         break;
 936                 } else if (TYPE_MATCH(type, ns_t_a, rec_type, "CNAME", key, query)) {
 937                         rc = rwrap_create_fake_cname_rr(key, value, rr);
 938                         if (rc == 0) {
 939                                 rc = rwrap_cname_recurse(hostfile, recursion+1,
 940                                                          value, rr + 1);
 941                         }
 942                         break;
 943                 } else if (TYPE_MATCH(type, ns_t_ptr,
 944                                       rec_type, "PTR", key, query)) {
 945                         rc = rwrap_create_fake_ptr_rr(key, value, rr);
 946                         break;
 947                 }
 948         }
 949
 950         if (rc == ENOENT && recursion == 0 && key != NULL) {
 951                 RWRAP_LOG(RWRAP_LOG_TRACE, "Record for [%s] not found\n", query);
 952                 memcpy(rr->key, key, strlen(key) + 1);
 953         }
 954
 955         fclose(fp);
 956         return rc;
 957 }
 958
 959 static ssize_t rwrap_fake_empty(int type,
 960                                 const char *question,
 961                                 uint8_t *answer,
 962                                 size_t anslen)
 963 {
 964         ssize_t resp_data;
 965         size_t remaining = anslen;
 966
 967         resp_data = rwrap_fake_header(&answer, remaining, 0, 0);
 968         if (resp_data < 0) {
 969                 return -1;
 970         }
 971         remaining -= resp_data;
 972
 973         resp_data += rwrap_fake_question(question, type, &answer, remaining);
 974         if (resp_data < 0) {
 975                 return -1;
 976         }
 977         remaining -= resp_data;
 978
 979         resp_data += rwrap_fake_rdata_common(type, 0, question,
 980                                             remaining, &answer);
 981         if (resp_data < 0) {
 982                 return -1;
 983         }
 984
 985         return resp_data;
 986 }
 987
 988 static inline bool rwrap_known_type(int type)
 989 {
 990         switch (type) {
 991         case ns_t_a:
 992         case ns_t_aaaa:
 993         case ns_t_ns:
 994         case ns_t_srv:
 995         case ns_t_uri:
 996         case ns_t_soa:
 997         case ns_t_cname:
 998         case ns_t_ptr:
 999                 return true;
1000         }
1001
1002         return false;
1003 }
1004
1005 static int rwrap_ancount(struct rwrap_fake_rr *rrs, int qtype)
1006 {
1007         int i;
1008         int ancount = 0;
1009
1010         /* For URI return the number of URIs. */
1011         if (qtype == ns_t_uri) {
1012                 for (i = 0; i < RWRAP_MAX_RECURSION; i++) {
1013                         if (rwrap_known_type(rrs[i].type) &&
1014                             rrs[i].type == qtype) {
1015                                 ancount++;
1016                         }
1017                 }
1018                 return ancount;
1019         }
1020
1021         /* Include all RRs in the stack until the sought type
1022          * in the answer section. This is the case i.e. when looking
1023          * up an A record but the name points to a CNAME
1024          */
1025         for (i = 0; i < RWRAP_MAX_RECURSION; i++) {
1026                 ancount++;
1027
1028                 if (rwrap_known_type(rrs[i].type) &&
1029                     rrs[i].type == qtype) {
1030                         break;
1031                 }
1032         }
1033
1034         /* Return 0 records if the sought type wasn't in the stack */
1035         return i < RWRAP_MAX_RECURSION ? ancount : 0;
1036 }
1037
1038 static int rwrap_arcount(struct rwrap_fake_rr *rrs, int ancount)
1039 {
1040         int i;
1041         int arcount = 0;
1042
1043         /* start from index ancount */
1044         for (i = ancount; i < RWRAP_MAX_RECURSION; i++) {
1045                 if (rwrap_known_type(rrs[i].type)) {
1046                         arcount++;
1047                 }
1048         }
1049
1050         return arcount;
1051 }
1052
1053 static ssize_t rwrap_add_rr(struct rwrap_fake_rr *rr,
1054                             uint8_t *answer,
1055                             size_t anslen)
1056 {
1057         ssize_t resp_data;
1058
1059         if (rr == NULL) {
1060                 RWRAP_LOG(RWRAP_LOG_ERROR, "Internal error!\n");
1061                 return -1;
1062         }
1063
1064         switch (rr->type) {
1065         case ns_t_a:
1066                 resp_data = rwrap_fake_a(rr, answer, anslen);
1067                 break;
1068         case ns_t_aaaa:
1069                 resp_data = rwrap_fake_aaaa(rr, answer, anslen);
1070                 break;
1071         case ns_t_ns:
1072                 resp_data = rwrap_fake_ns(rr, answer, anslen);
1073                 break;
1074         case ns_t_srv:
1075                 resp_data = rwrap_fake_srv(rr, answer, anslen);
1076                 break;
1077         case ns_t_uri:
1078                 resp_data = rwrap_fake_uri(rr, answer, anslen);
1079                 break;
1080         case ns_t_soa:
1081                 resp_data = rwrap_fake_soa(rr, answer, anslen);
1082                 break;
1083         case ns_t_cname:
1084                 resp_data = rwrap_fake_cname(rr, answer, anslen);
1085                 break;
1086         case ns_t_ptr:
1087                 resp_data = rwrap_fake_ptr(rr, answer, anslen);
1088                 break;
1089         default:
1090                 return -1;
1091         }
1092
1093         return resp_data;
1094 }
1095
1096 static ssize_t rwrap_fake_answer(struct rwrap_fake_rr *rrs,
1097                                  int type,
1098                                  uint8_t *answer,
1099                                  size_t anslen)
1100
1101 {
1102         ssize_t resp_data;
1103         ssize_t rrlen;
1104         size_t remaining = anslen;
1105         int ancount;
1106         int arcount;
1107         int i;
1108
1109         ancount = rwrap_ancount(rrs, type);
1110         arcount = rwrap_arcount(rrs, ancount);
1111         RWRAP_LOG(RWRAP_LOG_TRACE,
1112                   "Got %d answers and %d additional records\n", ancount, arcount);
1113
1114         resp_data = rwrap_fake_header(&answer, remaining, ancount, arcount);
1115         if (resp_data < 0) {
1116                 return -1;
1117         }
1118         remaining -= resp_data;
1119
1120         resp_data += rwrap_fake_question(rrs->key, rrs->type, &answer, remaining);
1121         if (resp_data < 0) {
1122                 return -1;
1123         }
1124         remaining -= resp_data;
1125
1126         /* answer */
1127         for (i = 0; i < ancount; i++) {
1128                 rrlen = rwrap_add_rr(&rrs[i], answer, remaining);
1129                 if (rrlen < 0) {
1130                         return -1;
1131                 }
1132                 remaining -= rrlen;
1133                 answer += rrlen;
1134                 resp_data += rrlen;
1135         }
1136
1137         /* add authoritative NS here? */
1138
1139         /* additional records */
1140         for (i = ancount; i < ancount + arcount; i++) {
1141                 rrlen = rwrap_add_rr(&rrs[i], answer, remaining);
1142                 if (rrlen < 0) {
1143                         return -1;
1144                 }
1145                 remaining -= rrlen;
1146                 answer += rrlen;
1147                 resp_data += rrlen;
1148         }
1149
1150         return resp_data;
1151 }
1152
1153 /* Reads in a file in the following format:
1154  * TYPE RDATA
1155  *
1156  * Malformed entries are silently skipped.
1157  * Allocates answer buffer of size anslen that has to be freed after use.
1158  */
1159 static int rwrap_res_fake_hosts(const char *hostfile,
1160                                 const char *query,
1161                                 int type,
1162                                 unsigned char *answer,
1163                                 size_t anslen)
1164 {
1165         int rc = ENOENT;
1166         char *query_name = NULL;
1167         size_t qlen = strlen(query);
1168         struct rwrap_fake_rr rrs[RWRAP_MAX_RECURSION];
1169         ssize_t resp_size;
1170
1171         RWRAP_LOG(RWRAP_LOG_TRACE,
1172                   "Searching in fake hosts file %s\n", hostfile);
1173
1174         if (qlen > 0 && query[qlen-1] == '.') {
1175                 qlen--;
1176         }
1177
1178         query_name = strndup(query, qlen);
1179         if (query_name == NULL) {
1180                 return -1;
1181         }
1182
1183         rwrap_fake_rr_init(rrs, RWRAP_MAX_RECURSION);
1184
1185         rc = rwrap_get_record(hostfile, 0, query_name, type, rrs);
1186         switch (rc) {
1187         case 0:
1188                 RWRAP_LOG(RWRAP_LOG_TRACE,
1189                                 "Found record for [%s]\n", query_name);
1190                 resp_size = rwrap_fake_answer(rrs, type, answer, anslen);
1191                 break;
1192         case ENOENT:
1193                 RWRAP_LOG(RWRAP_LOG_TRACE,
1194                                 "No record for [%s]\n", query_name);
1195                 resp_size = rwrap_fake_empty(type, rrs->key, answer, anslen);
1196                 break;
1197         default:
1198                 RWRAP_LOG(RWRAP_LOG_ERROR,
1199                                 "Error searching for [%s]\n", query_name);
1200                 free(query_name);
1201                 return -1;
1202         }
1203
1204         switch (resp_size) {
1205         case -1:
1206                 RWRAP_LOG(RWRAP_LOG_ERROR,
1207                                 "Error faking answer for [%s]\n", query_name);
1208                 break;
1209         default:
1210                 RWRAP_LOG(RWRAP_LOG_TRACE,
1211                                 "Successfully faked answer for [%s]\n",
1212                                 query_name);
1213                 break;
1214         }
1215
1216         free(query_name);
1217         return resp_size;
1218 }
1219
1220 /*********************************************************
1221  * RWRAP LOADING LIBC FUNCTIONS
1222  *********************************************************/
1223
1224 #include <dlfcn.h>
1225
1226 typedef int (*__libc_res_ninit)(struct __res_state *state);
1227 typedef int (*__libc___res_ninit)(struct __res_state *state);
1228 typedef void (*__libc_res_nclose)(struct __res_state *state);
1229 typedef void (*__libc___res_nclose)(struct __res_state *state);
1230 typedef int (*__libc_res_nquery)(struct __res_state *state,
1231                                  const char *dname,
1232                                  int class,
1233                                  int type,
1234                                  unsigned char *answer,
1235                                  int anslen);
1236 typedef int (*__libc___res_nquery)(struct __res_state *state,
1237                                    const char *dname,
1238                                    int class,
1239                                    int type,
1240                                    unsigned char *answer,
1241                                    int anslen);
1242 typedef int (*__libc_res_nsearch)(struct __res_state *state,
1243                                   const char *dname,
1244                                   int class,
1245                                   int type,
1246                                   unsigned char *answer,
1247                                   int anslen);
1248 typedef int (*__libc___res_nsearch)(struct __res_state *state,
1249                                     const char *dname,
1250                                     int class,
1251                                     int type,
1252                                     unsigned char *answer,
1253                                     int anslen);
1254
1255 #define RWRAP_SYMBOL_ENTRY(i) \
1256         union { \
1257                 __libc_##i f; \
1258                 void *obj; \
1259         } _libc_##i
1260
1261 struct rwrap_libc_symbols {
1262         RWRAP_SYMBOL_ENTRY(res_ninit);
1263         RWRAP_SYMBOL_ENTRY(__res_ninit);
1264         RWRAP_SYMBOL_ENTRY(res_nclose);
1265         RWRAP_SYMBOL_ENTRY(__res_nclose);
1266         RWRAP_SYMBOL_ENTRY(res_nquery);
1267         RWRAP_SYMBOL_ENTRY(__res_nquery);
1268         RWRAP_SYMBOL_ENTRY(res_nsearch);
1269         RWRAP_SYMBOL_ENTRY(__res_nsearch);
1270 };
1271 #undef RWRAP_SYMBOL_ENTRY
1272
1273 struct rwrap {
1274         struct {
1275                 void *handle;
1276                 struct rwrap_libc_symbols symbols;
1277         } libc;
1278
1279         struct {
1280                 void *handle;
1281                 struct rwrap_libc_symbols symbols;
1282         } libresolv;
1283
1284         bool initialised;
1285         bool enabled;
1286
1287         char *socket_dir;
1288 };
1289
1290 static struct rwrap rwrap;
1291
1292 enum rwrap_lib {
1293     RWRAP_LIBC,
1294     RWRAP_LIBRESOLV
1295 };
1296
1297 #ifndef NDEBUG
1298 static const char *rwrap_str_lib(enum rwrap_lib lib)
1299 {
1300         switch (lib) {
1301         case RWRAP_LIBC:
1302                 return "libc";
1303         case RWRAP_LIBRESOLV:
1304                 return "libresolv";
1305         }
1306
1307         /* Compiler would warn us about unhandled enum value if we get here */
1308         return "unknown";
1309 }
1310 #endif
1311
1312 static void *rwrap_load_lib_handle(enum rwrap_lib lib)
1313 {
1314         int flags = RTLD_LAZY;
1315         void *handle = NULL;
1316         int i;
1317
1318 #ifdef RTLD_DEEPBIND
1319         flags |= RTLD_DEEPBIND;
1320 #endif
1321
1322         switch (lib) {
1323         case RWRAP_LIBRESOLV:
1324 #ifdef HAVE_LIBRESOLV
1325                 handle = rwrap.libresolv.handle;
1326                 if (handle == NULL) {
1327                         for (i = 10; i >= 0; i--) {
1328                                 char soname[256] = {0};
1329
1330                                 snprintf(soname, sizeof(soname), "libresolv.so.%d", i);
1331                                 handle = dlopen(soname, flags);
1332                                 if (handle != NULL) {
1333                                         break;
1334                                 }
1335                         }
1336
1337                         rwrap.libresolv.handle = handle;
1338                 }
1339                 break;
1340 #endif
1341                 /* FALL TROUGH */
1342         case RWRAP_LIBC:
1343                 handle = rwrap.libc.handle;
1344 #ifdef LIBC_SO
1345                 if (handle == NULL) {
1346                         handle = dlopen(LIBC_SO, flags);
1347
1348                         rwrap.libc.handle = handle;
1349                 }
1350 #endif
1351                 if (handle == NULL) {
1352                         for (i = 10; i >= 0; i--) {
1353                                 char soname[256] = {0};
1354
1355                                 snprintf(soname, sizeof(soname), "libc.so.%d", i);
1356                                 handle = dlopen(soname, flags);
1357                                 if (handle != NULL) {
1358                                         break;
1359                                 }
1360                         }
1361
1362                         rwrap.libc.handle = handle;
1363                 }
1364                 break;
1365         }
1366
1367         if (handle == NULL) {
1368 #ifdef RTLD_NEXT
1369                 handle = rwrap.libc.handle = rwrap.libresolv.handle = RTLD_NEXT;
1370 #else
1371                 RWRAP_LOG(RWRAP_LOG_ERROR,
1372                           "Failed to dlopen library: %s\n",
1373                           dlerror());
1374                 exit(-1);
1375 #endif
1376         }
1377
1378         return handle;
1379 }
1380
1381 static void *_rwrap_bind_symbol(enum rwrap_lib lib, const char *fn_name)
1382 {
1383         void *handle;
1384         void *func;
1385
1386         handle = rwrap_load_lib_handle(lib);
1387
1388         func = dlsym(handle, fn_name);
1389         if (func == NULL) {
1390                 RWRAP_LOG(RWRAP_LOG_ERROR,
1391                                 "Failed to find %s: %s\n",
1392                                 fn_name, dlerror());
1393                 exit(-1);
1394         }
1395
1396         RWRAP_LOG(RWRAP_LOG_TRACE,
1397                         "Loaded %s from %s",
1398                         fn_name, rwrap_str_lib(lib));
1399         return func;
1400 }
1401
1402 #define rwrap_bind_symbol_libc(sym_name) \
1403         if (rwrap.libc.symbols._libc_##sym_name.obj == NULL) { \
1404                 rwrap.libc.symbols._libc_##sym_name.obj = \
1405                         _rwrap_bind_symbol(RWRAP_LIBC, #sym_name); \
1406         }
1407
1408 #define rwrap_bind_symbol_libresolv(sym_name) \
1409         if (rwrap.libresolv.symbols._libc_##sym_name.obj == NULL) { \
1410                 rwrap.libresolv.symbols._libc_##sym_name.obj = \
1411                         _rwrap_bind_symbol(RWRAP_LIBRESOLV, #sym_name); \
1412         }
1413
1414 /*
1415  * IMPORTANT
1416  *
1417  * Functions especially from libc need to be loaded individually, you can't load
1418  * all at once or gdb will segfault at startup. The same applies to valgrind and
1419  * has probably something todo with with the linker.
1420  * So we need load each function at the point it is called the first time.
1421  */
1422
1423 static int libc_res_ninit(struct __res_state *state)
1424 {
1425 #if !defined(res_ninit) && defined(HAVE_RES_NINIT)
1426
1427 #if defined(HAVE_RES_NINIT_IN_LIBRESOLV)
1428         rwrap_bind_symbol_libresolv(res_ninit);
1429
1430         return rwrap.libresolv.symbols._libc_res_ninit.f(state);
1431 #else /* HAVE_RES_NINIT_IN_LIBRESOLV */
1432         rwrap_bind_symbol_libc(res_ninit);
1433
1434         return rwrap.libc.symbols._libc_res_ninit.f(state);
1435 #endif /* HAVE_RES_NINIT_IN_LIBRESOLV */
1436
1437 #elif defined(HAVE___RES_NINIT)
1438         rwrap_bind_symbol_libc(__res_ninit);
1439
1440         return rwrap.libc.symbols._libc___res_ninit.f(state);
1441 #else
1442 #error "No res_ninit function"
1443 #endif
1444 }
1445
1446 static void libc_res_nclose(struct __res_state *state)
1447 {
1448 #if !defined(res_close) && defined(HAVE_RES_NCLOSE)
1449
1450 #if defined(HAVE_RES_NCLOSE_IN_LIBRESOLV)
1451         rwrap_bind_symbol_libresolv(res_nclose);
1452
1453         rwrap.libresolv.symbols._libc_res_nclose.f(state);
1454         return;
1455 #else /* HAVE_RES_NCLOSE_IN_LIBRESOLV */
1456         rwrap_bind_symbol_libc(res_nclose);
1457
1458         rwrap.libc.symbols._libc_res_nclose.f(state);
1459         return;
1460 #endif /* HAVE_RES_NCLOSE_IN_LIBRESOLV */
1461
1462 #elif defined(HAVE___RES_NCLOSE)
1463         rwrap_bind_symbol_libc(__res_nclose);
1464
1465         rwrap.libc.symbols._libc___res_nclose.f(state);
1466 #else
1467 #error "No res_nclose function"
1468 #endif
1469 }
1470
1471 static int libc_res_nquery(struct __res_state *state,
1472                            const char *dname,
1473                            int class,
1474                            int type,
1475                            unsigned char *answer,
1476                            int anslen)
1477 {
1478 #if !defined(res_nquery) && defined(HAVE_RES_NQUERY)
1479         rwrap_bind_symbol_libresolv(res_nquery);
1480
1481         return rwrap.libresolv.symbols._libc_res_nquery.f(state,
1482                                                           dname,
1483                                                           class,
1484                                                           type,
1485                                                           answer,
1486                                                           anslen);
1487 #elif defined(HAVE___RES_NQUERY)
1488         rwrap_bind_symbol_libresolv(__res_nquery);
1489
1490         return rwrap.libresolv.symbols._libc___res_nquery.f(state,
1491                                                             dname,
1492                                                             class,
1493                                                             type,
1494                                                             answer,
1495                                                             anslen);
1496 #else
1497 #error "No res_nquery function"
1498 #endif
1499 }
1500
1501 static int libc_res_nsearch(struct __res_state *state,
1502                             const char *dname,
1503                             int class,
1504                             int type,
1505                             unsigned char *answer,
1506                             int anslen)
1507 {
1508 #if !defined(res_nsearch) && defined(HAVE_RES_NSEARCH)
1509         rwrap_bind_symbol_libresolv(res_nsearch);
1510
1511         return rwrap.libresolv.symbols._libc_res_nsearch.f(state,
1512                                                            dname,
1513                                                            class,
1514                                                            type,
1515                                                            answer,
1516                                                            anslen);
1517 #elif defined(HAVE___RES_NSEARCH)
1518         rwrap_bind_symbol_libresolv(__res_nsearch);
1519
1520         return rwrap.libresolv.symbols._libc___res_nsearch.f(state,
1521                                                              dname,
1522                                                              class,
1523                                                              type,
1524                                                              answer,
1525                                                              anslen);
1526 #else
1527 #error "No res_nsearch function"
1528 #endif
1529 }
1530
1531 /****************************************************************************
1532  *   RES_HELPER
1533  ***************************************************************************/
1534
1535 static int rwrap_parse_resolv_conf(struct __res_state *state,
1536                                    const char *resolv_conf)
1537 {
1538         FILE *fp;
1539         char buf[BUFSIZ];
1540         int nserv = 0;
1541
1542         fp = fopen(resolv_conf, "r");
1543         if (fp == NULL) {
1544                 RWRAP_LOG(RWRAP_LOG_ERROR,
1545                           "Opening %s failed: %s",
1546                           resolv_conf, strerror(errno));
1547                 return -1;
1548         }
1549
1550         while(fgets(buf, sizeof(buf), fp) != NULL) {
1551                 char *p;
1552
1553                 /* Ignore comments */
1554                 if (buf[0] == '#' || buf[0] == ';') {
1555                         continue;
1556                 }
1557
1558                 if (RESOLV_MATCH(buf, "nameserver") && nserv < MAXNS) {
1559                         struct in_addr a;
1560                         char *q;
1561                         int ok;
1562
1563                         p = buf + strlen("nameserver");
1564
1565                         /* Skip spaces and tabs */
1566                         while(isblank((int)p[0])) {
1567                                 p++;
1568                         }
1569
1570                         q = p;
1571                         while(q[0] != '\n' && q[0] != '\0') {
1572                                 q++;
1573                         }
1574                         q[0] = '\0';
1575
1576                         ok = inet_pton(AF_INET, p, &a);
1577                         if (ok) {
1578                                 state->nsaddr_list[state->nscount] = (struct sockaddr_in) {
1579                                         .sin_family = AF_INET,
1580                                         .sin_addr = a,
1581                                         .sin_port = htons(53),
1582                                         .sin_zero = { 0 },
1583                                 };
1584
1585                                 state->nscount++;
1586                                 nserv++;
1587                         } else {
1588 #ifdef HAVE_RESOLV_IPV6_NSADDRS
1589                                 /* IPv6 */
1590                                 struct in6_addr a6;
1591                                 ok = inet_pton(AF_INET6, p, &a6);
1592                                 if (ok) {
1593                                         struct sockaddr_in6 *sa6;
1594
1595                                         sa6 = malloc(sizeof(*sa6));
1596                                         if (sa6 == NULL) {
1597                                                 fclose(fp);
1598                                                 return -1;
1599                                         }
1600
1601                                         sa6->sin6_family = AF_INET6;
1602                                         sa6->sin6_port = htons(53);
1603                                         sa6->sin6_flowinfo = 0;
1604                                         sa6->sin6_addr = a6;
1605
1606                                         state->_u._ext.nsaddrs[state->_u._ext.nscount] = sa6;
1607                                         state->_u._ext.nssocks[state->_u._ext.nscount] = -1;
1608                                         state->_u._ext.nsmap[state->_u._ext.nscount] = MAXNS + 1;
1609
1610                                         state->_u._ext.nscount++;
1611                                         nserv++;
1612                                 } else {
1613                                         RWRAP_LOG(RWRAP_LOG_ERROR,
1614                                                 "Malformed DNS server");
1615                                         continue;
1616                                 }
1617 #else /* !HAVE_RESOLV_IPV6_NSADDRS */
1618                                 /*
1619                                  * BSD uses an opaque structure to store the
1620                                  * IPv6 addresses. So we can not simply store
1621                                  * these addresses the same way as above.
1622                                  */
1623                                 RWRAP_LOG(RWRAP_LOG_WARN,
1624                                           "resolve_wrapper does not support "
1625                                           "IPv6 on this platform");
1626                                         continue;
1627 #endif
1628                         }
1629                         continue;
1630                 } /* TODO: match other keywords */
1631         }
1632
1633         if (ferror(fp)) {
1634                 RWRAP_LOG(RWRAP_LOG_ERROR,
1635                           "Reading from %s failed",
1636                           resolv_conf);
1637                 fclose(fp);
1638                 return -1;
1639         }
1640
1641         fclose(fp);
1642         return 0;
1643 }
1644
1645 /****************************************************************************
1646  *   RES_NINIT
1647  ***************************************************************************/
1648
1649 static int rwrap_res_ninit(struct __res_state *state)
1650 {
1651         int rc;
1652
1653         rc = libc_res_ninit(state);
1654         if (rc == 0) {
1655                 const char *resolv_conf = getenv("RESOLV_WRAPPER_CONF");
1656
1657                 if (resolv_conf != NULL) {
1658                         uint16_t i;
1659
1660                         (void)i; /* maybe unused */
1661
1662                         /* Delete name servers */
1663                         state->nscount = 0;
1664                         memset(state->nsaddr_list, 0, sizeof(state->nsaddr_list));
1665
1666 #ifdef HAVE_RESOLV_IPV6_NSADDRS
1667                         state->_u._ext.nscount = 0;
1668                         for (i = 0; i < state->_u._ext.nscount; i++) {
1669                                 SAFE_FREE(state->_u._ext.nsaddrs[i]);
1670                         }
1671 #endif
1672
1673                         rc = rwrap_parse_resolv_conf(state, resolv_conf);
1674                 }
1675         }
1676
1677         return rc;
1678 }
1679
1680 #if !defined(res_ninit) && defined(HAVE_RES_NINIT)
1681 int res_ninit(struct __res_state *state)
1682 #elif defined(HAVE___RES_NINIT)
1683 int __res_ninit(struct __res_state *state)
1684 #endif
1685 {
1686         return rwrap_res_ninit(state);
1687 }
1688
1689 /****************************************************************************
1690  *   RES_INIT
1691  ***************************************************************************/
1692
1693 static struct __res_state rwrap_res_state;
1694
1695 static int rwrap_res_init(void)
1696 {
1697         int rc;
1698
1699         rc = rwrap_res_ninit(&rwrap_res_state);
1700
1701         return rc;
1702 }
1703
1704 #if !defined(res_ninit) && defined(HAVE_RES_INIT)
1705 int res_init(void)
1706 #elif defined(HAVE___RES_INIT)
1707 int __res_init(void)
1708 #endif
1709 {
1710         return rwrap_res_init();
1711 }
1712
1713 /****************************************************************************
1714  *   RES_NCLOSE
1715  ***************************************************************************/
1716
1717 static void rwrap_res_nclose(struct __res_state *state)
1718 {
1719 #ifdef HAVE_RESOLV_IPV6_NSADDRS
1720         int i;
1721 #endif
1722
1723         libc_res_nclose(state);
1724
1725 #ifdef HAVE_RESOLV_IPV6_NSADDRS
1726         if (state != NULL) {
1727                 for (i = 0; i < state->_u._ext.nscount; i++) {
1728                         SAFE_FREE(state->_u._ext.nsaddrs[i]);
1729                 }
1730         }
1731 #endif
1732 }
1733
1734 #if !defined(res_nclose) && defined(HAVE_RES_NCLOSE)
1735 void res_nclose(struct __res_state *state)
1736 #elif defined(HAVE___RES_NCLOSE)
1737 void __res_nclose(struct __res_state *state)
1738 #endif
1739 {
1740         rwrap_res_nclose(state);
1741 }
1742
1743 /****************************************************************************
1744  *   RES_CLOSE
1745  ***************************************************************************/
1746
1747 static void rwrap_res_close(void)
1748 {
1749         rwrap_res_nclose(&rwrap_res_state);
1750 }
1751
1752 #if defined(HAVE_RES_CLOSE)
1753 void res_close(void)
1754 #elif defined(HAVE___RES_CLOSE)
1755 void __res_close(void)
1756 #endif
1757 {
1758         rwrap_res_close();
1759 }
1760
1761 /****************************************************************************
1762  *   RES_NQUERY
1763  ***************************************************************************/
1764
1765 static int rwrap_res_nquery(struct __res_state *state,
1766                             const char *dname,
1767                             int class,
1768                             int type,
1769                             unsigned char *answer,
1770                             int anslen)
1771 {
1772         int rc;
1773         const char *fake_hosts;
1774 #ifndef NDEBUG
1775         int i;
1776 #endif
1777
1778         RWRAP_LOG(RWRAP_LOG_TRACE,
1779                   "Resolve the domain name [%s] - class=%d, type=%d",
1780                   dname, class, type);
1781 #ifndef NDEBUG
1782         for (i = 0; i < state->nscount; i++) {
1783                 char ip[INET6_ADDRSTRLEN];
1784
1785                 inet_ntop(AF_INET, &state->nsaddr_list[i].sin_addr, ip, sizeof(ip));
1786                 RWRAP_LOG(RWRAP_LOG_TRACE,
1787                           "        nameserver: %s",
1788                           ip);
1789         }
1790 #endif
1791
1792         fake_hosts = getenv("RESOLV_WRAPPER_HOSTS");
1793         if (fake_hosts != NULL) {
1794                 rc = rwrap_res_fake_hosts(fake_hosts, dname, type, answer, anslen);
1795         } else {
1796                 rc = libc_res_nquery(state, dname, class, type, answer, anslen);
1797         }
1798
1799
1800         RWRAP_LOG(RWRAP_LOG_TRACE,
1801                   "The returned response length is: %d",
1802                   rc);
1803
1804         return rc;
1805 }
1806
1807 #if !defined(res_nquery) && defined(HAVE_RES_NQUERY)
1808 int res_nquery(struct __res_state *state,
1809                const char *dname,
1810                int class,
1811                int type,
1812                unsigned char *answer,
1813                int anslen)
1814 #elif defined(HAVE___RES_NQUERY)
1815 int __res_nquery(struct __res_state *state,
1816                  const char *dname,
1817                  int class,
1818                  int type,
1819                  unsigned char *answer,
1820                  int anslen)
1821 #endif
1822 {
1823         return rwrap_res_nquery(state, dname, class, type, answer, anslen);
1824 }
1825
1826 /****************************************************************************
1827  *   RES_QUERY
1828  ***************************************************************************/
1829
1830 static int rwrap_res_query(const char *dname,
1831                            int class,
1832                            int type,
1833                            unsigned char *answer,
1834                            int anslen)
1835 {
1836         int rc;
1837
1838         rc = rwrap_res_ninit(&rwrap_res_state);
1839         if (rc != 0) {
1840                 return rc;
1841         }
1842
1843         rc = rwrap_res_nquery(&rwrap_res_state,
1844                               dname,
1845                               class,
1846                               type,
1847                               answer,
1848                               anslen);
1849
1850         return rc;
1851 }
1852
1853 #if !defined(res_query) && defined(HAVE_RES_QUERY)
1854 int res_query(const char *dname,
1855               int class,
1856               int type,
1857               unsigned char *answer,
1858               int anslen)
1859 #elif defined(HAVE___RES_QUERY)
1860 int __res_query(const char *dname,
1861                 int class,
1862                 int type,
1863                 unsigned char *answer,
1864                 int anslen)
1865 #endif
1866 {
1867         return rwrap_res_query(dname, class, type, answer, anslen);
1868 }
1869
1870 /****************************************************************************
1871  *   RES_NSEARCH
1872  ***************************************************************************/
1873
1874 static int rwrap_res_nsearch(struct __res_state *state,
1875                              const char *dname,
1876                              int class,
1877                              int type,
1878                              unsigned char *answer,
1879                              int anslen)
1880 {
1881         int rc;
1882         const char *fake_hosts;
1883 #ifndef NDEBUG
1884         int i;
1885 #endif
1886
1887         RWRAP_LOG(RWRAP_LOG_TRACE,
1888                   "Resolve the domain name [%s] - class=%d, type=%d",
1889                   dname, class, type);
1890 #ifndef NDEBUG
1891         for (i = 0; i < state->nscount; i++) {
1892                 char ip[INET6_ADDRSTRLEN];
1893
1894                 inet_ntop(AF_INET, &state->nsaddr_list[i].sin_addr, ip, sizeof(ip));
1895                 RWRAP_LOG(RWRAP_LOG_TRACE,
1896                           "        nameserver: %s",
1897                           ip);
1898         }
1899 #endif
1900
1901         fake_hosts = getenv("RESOLV_WRAPPER_HOSTS");
1902         if (fake_hosts != NULL) {
1903                 rc = rwrap_res_fake_hosts(fake_hosts, dname, type, answer, anslen);
1904         } else {
1905                 rc = libc_res_nsearch(state, dname, class, type, answer, anslen);
1906         }
1907
1908         RWRAP_LOG(RWRAP_LOG_TRACE,
1909                   "The returned response length is: %d",
1910                   rc);
1911
1912         return rc;
1913 }
1914
1915 #if !defined(res_nsearch) && defined(HAVE_RES_NSEARCH)
1916 int res_nsearch(struct __res_state *state,
1917                 const char *dname,
1918                 int class,
1919                 int type,
1920                 unsigned char *answer,
1921                 int anslen)
1922 #elif defined(HAVE___RES_NSEARCH)
1923 int __res_nsearch(struct __res_state *state,
1924                   const char *dname,
1925                   int class,
1926                   int type,
1927                   unsigned char *answer,
1928                   int anslen)
1929 #endif
1930 {
1931         return rwrap_res_nsearch(state, dname, class, type, answer, anslen);
1932 }
1933
1934 /****************************************************************************
1935  *   RES_SEARCH
1936  ***************************************************************************/
1937
1938 static int rwrap_res_search(const char *dname,
1939                             int class,
1940                             int type,
1941                             unsigned char *answer,
1942                             int anslen)
1943 {
1944         int rc;
1945
1946         rc = rwrap_res_ninit(&rwrap_res_state);
1947         if (rc != 0) {
1948                 return rc;
1949         }
1950
1951         rc = rwrap_res_nsearch(&rwrap_res_state,
1952                                dname,
1953                                class,
1954                                type,
1955                                answer,
1956                                anslen);
1957
1958         return rc;
1959 }
1960
1961 #if !defined(res_search) && defined(HAVE_RES_SEARCH)
1962 int res_search(const char *dname,
1963                int class,
1964                int type,
1965                unsigned char *answer,
1966                int anslen)
1967 #elif defined(HAVE___RES_SEARCH)
1968 int __res_search(const char *dname,
1969                  int class,
1970                  int type,
1971                  unsigned char *answer,
1972                  int anslen)
1973 #endif
1974 {
1975         return rwrap_res_search(dname, class, type, answer, anslen);
1976 }