src/dnsproxy.c

   1 /*
   2  *
   3  *  Connection Manager
   4  *
   5  *  Copyright (C) 2007-2010  Intel Corporation. All rights reserved.
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <errno.h>
  27 #include <unistd.h>
  28 #include <string.h>
  29 #include <stdint.h>
  30 #include <arpa/inet.h>
  31 #include <netinet/in.h>
  32 #include <sys/types.h>
  33 #include <sys/socket.h>
  34 #include <netdb.h>
  35 #include <resolv.h>
  36 #include <gweb/gresolv.h>
  37
  38 #include <glib.h>
  39
  40 #include "connman.h"
  41
  42 #if __BYTE_ORDER == __LITTLE_ENDIAN
  43 struct domain_hdr {
  44         uint16_t id;
  45         uint8_t rd:1;
  46         uint8_t tc:1;
  47         uint8_t aa:1;
  48         uint8_t opcode:4;
  49         uint8_t qr:1;
  50         uint8_t rcode:4;
  51         uint8_t z:3;
  52         uint8_t ra:1;
  53         uint16_t qdcount;
  54         uint16_t ancount;
  55         uint16_t nscount;
  56         uint16_t arcount;
  57 } __attribute__ ((packed));
  58 #elif __BYTE_ORDER == __BIG_ENDIAN
  59 struct domain_hdr {
  60         uint16_t id;
  61         uint8_t qr:1;
  62         uint8_t opcode:4;
  63         uint8_t aa:1;
  64         uint8_t tc:1;
  65         uint8_t rd:1;
  66         uint8_t ra:1;
  67         uint8_t z:3;
  68         uint8_t rcode:4;
  69         uint16_t qdcount;
  70         uint16_t ancount;
  71         uint16_t nscount;
  72         uint16_t arcount;
  73 } __attribute__ ((packed));
  74 #else
  75 #error "Unknown byte order"
  76 #endif
  77
  78 struct partial_reply {
  79         uint16_t len;
  80         uint16_t received;
  81         unsigned char buf[];
  82 };
  83
  84 struct server_data {
  85         char *interface;
  86         GList *domains;
  87         char *server;
  88         int protocol;
  89         GIOChannel *channel;
  90         guint watch;
  91         guint timeout;
  92         gboolean enabled;
  93         gboolean connected;
  94         struct partial_reply *incoming_reply;
  95 };
  96
  97 struct request_data {
  98         union {
  99                 struct sockaddr_in6 __sin6; /* Only for the length */
 100                 struct sockaddr sa;
 101         };
 102         socklen_t sa_len;
 103         int client_sk;
 104         int protocol;
 105         guint16 srcid;
 106         guint16 dstid;
 107         guint16 altid;
 108         guint timeout;
 109         guint watch;
 110         guint numserv;
 111         guint numresp;
 112         gpointer request;
 113         gsize request_len;
 114         gpointer name;
 115         gpointer resp;
 116         gsize resplen;
 117         struct listener_data *ifdata;
 118         gboolean append_domain;
 119 };
 120
 121 struct listener_data {
 122         char *ifname;
 123         GIOChannel *udp_listener_channel;
 124         guint udp_listener_watch;
 125         GIOChannel *tcp_listener_channel;
 126         guint tcp_listener_watch;
 127 };
 128
 129 struct cache_data {
 130         time_t inserted;
 131         time_t valid_until;
 132         time_t cache_until;
 133         int timeout;
 134         uint16_t type;
 135         uint16_t answers;
 136         unsigned int data_len;
 137         unsigned char *data; /* contains DNS header + body */
 138 };
 139
 140 struct cache_entry {
 141         char *key;
 142         int want_refresh;
 143         int hits;
 144         struct cache_data *ipv4;
 145         struct cache_data *ipv6;
 146 };
 147
 148 struct domain_question {
 149         uint16_t type;
 150         uint16_t class;
 151 } __attribute__ ((packed));
 152
 153 struct domain_rr {
 154         uint16_t type;
 155         uint16_t class;
 156         uint32_t ttl;
 157         uint16_t rdlen;
 158 } __attribute__ ((packed));
 159
 160 /*
 161  * We limit how long the cached DNS entry stays in the cache.
 162  * By default the TTL (time-to-live) of the DNS response is used
 163  * when setting the cache entry life time. The value is in seconds.
 164  */
 165 #define MAX_CACHE_TTL (60 * 30)
 166 /*
 167  * Also limit the other end, cache at least for 30 seconds.
 168  */
 169 #define MIN_CACHE_TTL (30)
 170
 171 /*
 172  * We limit the cache size to some sane value so that cached data does
 173  * not occupy too much memory. Each cached entry occupies on average
 174  * about 100 bytes memory (depending on DNS name length).
 175  * Example: caching www.connman.net uses 97 bytes memory.
 176  * The value is the max amount of cached DNS responses (count).
 177  */
 178 #define MAX_CACHE_SIZE 256
 179
 180 static int cache_size;
 181 static GHashTable *cache;
 182 static int cache_refcount;
 183 static GSList *server_list = NULL;
 184 static GSList *request_list = NULL;
 185 static GSList *request_pending_list = NULL;
 186 static guint16 request_id = 0x0000;
 187 static GHashTable *listener_table = NULL;
 188 static time_t next_refresh;
 189
 190 static int protocol_offset(int protocol)
 191 {
 192         switch (protocol) {
 193         case IPPROTO_UDP:
 194                 return 0;
 195
 196         case IPPROTO_TCP:
 197                 return 2;
 198
 199         default:
 200                 return -EINVAL;
 201         }
 202
 203 }
 204
 205 /*
 206  * There is a power and efficiency benefit to have entries
 207  * in our cache expire at the same time. To this extend,
 208  * we round down the cache valid time to common boundaries.
 209  */
 210 static time_t round_down_ttl(time_t end_time, int ttl)
 211 {
 212         if (ttl < 15)
 213                 return end_time;
 214
 215         /* Less than 5 minutes, round to 10 second boundary */
 216         if (ttl < 300) {
 217                 end_time = end_time / 10;
 218                 end_time = end_time * 10;
 219         } else { /* 5 or more minutes, round to 30 seconds */
 220                 end_time = end_time / 30;
 221                 end_time = end_time * 30;
 222         }
 223         return end_time;
 224 }
 225
 226 static struct request_data *find_request(guint16 id)
 227 {
 228         GSList *list;
 229
 230         for (list = request_list; list; list = list->next) {
 231                 struct request_data *req = list->data;
 232
 233                 if (req->dstid == id || req->altid == id)
 234                         return req;
 235         }
 236
 237         return NULL;
 238 }
 239
 240 static struct server_data *find_server(const char *interface,
 241                                         const char *server,
 242                                                 int protocol)
 243 {
 244         GSList *list;
 245
 246         DBG("interface %s server %s", interface, server);
 247
 248         for (list = server_list; list; list = list->next) {
 249                 struct server_data *data = list->data;
 250
 251                 if (interface == NULL && data->interface == NULL &&
 252                                 g_str_equal(data->server, server) == TRUE &&
 253                                 data->protocol == protocol)
 254                         return data;
 255
 256                 if (interface == NULL ||
 257                                 data->interface == NULL || data->server == NULL)
 258                         continue;
 259
 260                 if (g_str_equal(data->interface, interface) == TRUE &&
 261                                 g_str_equal(data->server, server) == TRUE &&
 262                                 data->protocol == protocol)
 263                         return data;
 264         }
 265
 266         return NULL;
 267 }
 268
 269 /* we can keep using the same resolve's */
 270 static GResolv *ipv4_resolve;
 271 static GResolv *ipv6_resolve;
 272
 273 static void dummy_resolve_func(GResolvResultStatus status,
 274                                         char **results, gpointer user_data)
 275 {
 276 }
 277
 278 /*
 279  * Refresh a DNS entry, but also age the hit count a bit */
 280 static void refresh_dns_entry(struct cache_entry *entry, char *name)
 281 {
 282         int age = 1;
 283         if (ipv4_resolve == NULL) {
 284                 ipv4_resolve = g_resolv_new(0);
 285                 g_resolv_set_address_family(ipv4_resolve, AF_INET);
 286                 g_resolv_add_nameserver(ipv4_resolve, "127.0.0.1", 53, 0);
 287         }
 288         if (ipv6_resolve == NULL) {
 289                 ipv6_resolve = g_resolv_new(0);
 290                 g_resolv_set_address_family(ipv6_resolve, AF_INET6);
 291                 g_resolv_add_nameserver(ipv6_resolve, "127.0.0.1", 53, 0);
 292         }
 293
 294         if (entry->ipv4 == NULL) {
 295                 DBG("Refresing A record for %s", name);
 296                 g_resolv_lookup_hostname(ipv4_resolve, name,
 297                                         dummy_resolve_func, NULL);
 298                 age = 4;
 299         }
 300         if (entry->ipv6 == NULL) {
 301                 DBG("Refresing AAAA record for %s", name);
 302                 g_resolv_lookup_hostname(ipv6_resolve, name,
 303                                         dummy_resolve_func, NULL);
 304                 age = 4;
 305         }
 306         entry->hits -= age;
 307         if (entry->hits < 0)
 308                 entry->hits = 0;
 309 }
 310
 311
 312
 313 static int dns_name_length(unsigned char *buf)
 314 {
 315         if ((buf[0] & NS_CMPRSFLGS) == NS_CMPRSFLGS) /* compressed name */
 316                 return 2;
 317         return strlen((char *)buf);
 318 }
 319
 320 static void update_cached_ttl(unsigned char *buf, int len, int new_ttl)
 321 {
 322         unsigned char *c;
 323         uint32_t *i;
 324         uint16_t *w;
 325         int l;
 326
 327         /* skip the header */
 328         c = buf + 12;
 329         len -= 12;
 330
 331         /* skip the query, which is a name and 2 16 bit words */
 332         l = dns_name_length(c);
 333         c += l;
 334         len -= l;
 335         c += 4;
 336         len -= 4;
 337
 338         /* now we get the answer records */
 339
 340         while (len > 0) {
 341                 /* first a name */
 342                 l = dns_name_length(c);
 343                 c += l;
 344                 len -= l;
 345                 if (len < 0)
 346                         break;
 347                 /* then type + class, 2 bytes each */
 348                 c += 4;
 349                 len -= 4;
 350                 if (len < 0)
 351                         break;
 352
 353                 /* now the 4 byte TTL field */
 354                 i = (uint32_t *)c;
 355                 *i = htonl(new_ttl);
 356                 c += 4;
 357                 len -= 4;
 358                 if (len < 0)
 359                         break;
 360
 361                 /* now the 2 byte rdlen field */
 362                 w = (uint16_t *)c;
 363                 c += ntohs(*w) + 2;
 364                 len -= ntohs(*w) + 2;
 365         }
 366 }
 367
 368
 369
 370 static void send_cached_response(int sk, unsigned char *buf, int len,
 371                                 const struct sockaddr *to, socklen_t tolen,
 372                                 int protocol, int id, uint16_t answers, int ttl)
 373 {
 374         struct domain_hdr *hdr;
 375         int err, offset = protocol_offset(protocol);
 376
 377         if (offset < 0)
 378                 return;
 379
 380         if (len < 12)
 381                 return;
 382
 383         hdr = (void *) (buf + offset);
 384
 385         hdr->id = id;
 386         hdr->qr = 1;
 387         hdr->rcode = 0;
 388         hdr->ancount = htons(answers);
 389         hdr->nscount = 0;
 390         hdr->arcount = 0;
 391
 392         /* if this is a negative reply, we are authorative */
 393         if (answers == 0)
 394                 hdr->aa = 1;
 395         else
 396                 update_cached_ttl(buf, len, ttl);
 397
 398         DBG("id 0x%04x answers %d", hdr->id, answers);
 399
 400         err = sendto(sk, buf, len, 0, to, tolen);
 401         if (err < 0) {
 402                 connman_error("Cannot send cached DNS response: %s",
 403                                 strerror(errno));
 404                 return;
 405         }
 406 }
 407
 408 static void send_response(int sk, unsigned char *buf, int len,
 409                                 const struct sockaddr *to, socklen_t tolen,
 410                                 int protocol)
 411 {
 412         struct domain_hdr *hdr;
 413         int err, offset = protocol_offset(protocol);
 414
 415         DBG("");
 416
 417         if (offset < 0)
 418                 return;
 419
 420         if (len < 12)
 421                 return;
 422
 423         hdr = (void *) (buf + offset);
 424
 425         DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode);
 426
 427         hdr->qr = 1;
 428         hdr->rcode = 2;
 429
 430         hdr->ancount = 0;
 431         hdr->nscount = 0;
 432         hdr->arcount = 0;
 433
 434         err = sendto(sk, buf, len, 0, to, tolen);
 435         if (err < 0) {
 436                 connman_error("Failed to send DNS response: %s",
 437                                 strerror(errno));
 438                 return;
 439         }
 440 }
 441
 442 static gboolean request_timeout(gpointer user_data)
 443 {
 444         struct request_data *req = user_data;
 445         struct listener_data *ifdata;
 446
 447         DBG("id 0x%04x", req->srcid);
 448
 449         if (req == NULL)
 450                 return FALSE;
 451
 452         ifdata = req->ifdata;
 453
 454         request_list = g_slist_remove(request_list, req);
 455         req->numserv--;
 456
 457         if (req->resplen > 0 && req->resp != NULL) {
 458                 int sk, err;
 459
 460                 sk = g_io_channel_unix_get_fd(ifdata->udp_listener_channel);
 461
 462                 err = sendto(sk, req->resp, req->resplen, 0,
 463                                                 &req->sa, req->sa_len);
 464                 if (err < 0)
 465                         return FALSE;
 466         } else if (req->request && req->numserv == 0) {
 467                 struct domain_hdr *hdr;
 468
 469                 if (req->protocol == IPPROTO_TCP) {
 470                         hdr = (void *) (req->request + 2);
 471                         hdr->id = req->srcid;
 472                         send_response(req->client_sk, req->request,
 473                                 req->request_len, NULL, 0, IPPROTO_TCP);
 474
 475                 } else if (req->protocol == IPPROTO_UDP) {
 476                         int sk;
 477
 478                         hdr = (void *) (req->request);
 479                         hdr->id = req->srcid;
 480                         sk = g_io_channel_unix_get_fd(
 481                                                 ifdata->udp_listener_channel);
 482                         send_response(sk, req->request, req->request_len,
 483                                         &req->sa, req->sa_len, IPPROTO_UDP);
 484                 }
 485         }
 486
 487         g_free(req->resp);
 488         g_free(req);
 489
 490         return FALSE;
 491 }
 492
 493 static int append_query(unsigned char *buf, unsigned int size,
 494                                 const char *query, const char *domain)
 495 {
 496         unsigned char *ptr = buf;
 497         char *offset;
 498         int len;
 499
 500         DBG("query %s domain %s", query, domain);
 501
 502         offset = (char *) query;
 503         while (offset != NULL) {
 504                 char *tmp;
 505
 506                 tmp = strchr(offset, '.');
 507                 if (tmp == NULL) {
 508                         len = strlen(offset);
 509                         if (len == 0)
 510                                 break;
 511                         *ptr = len;
 512                         memcpy(ptr + 1, offset, len);
 513                         ptr += len + 1;
 514                         break;
 515                 }
 516
 517                 *ptr = tmp - offset;
 518                 memcpy(ptr + 1, offset, tmp - offset);
 519                 ptr += tmp - offset + 1;
 520
 521                 offset = tmp + 1;
 522         }
 523
 524         offset = (char *) domain;
 525         while (offset != NULL) {
 526                 char *tmp;
 527
 528                 tmp = strchr(offset, '.');
 529                 if (tmp == NULL) {
 530                         len = strlen(offset);
 531                         if (len == 0)
 532                                 break;
 533                         *ptr = len;
 534                         memcpy(ptr + 1, offset, len);
 535                         ptr += len + 1;
 536                         break;
 537                 }
 538
 539                 *ptr = tmp - offset;
 540                 memcpy(ptr + 1, offset, tmp - offset);
 541                 ptr += tmp - offset + 1;
 542
 543                 offset = tmp + 1;
 544         }
 545
 546         *ptr++ = 0x00;
 547
 548         return ptr - buf;
 549 }
 550
 551 static gboolean cache_check_is_valid(struct cache_data *data,
 552                                 time_t current_time)
 553 {
 554         if (data == NULL)
 555                 return FALSE;
 556
 557         if (data->cache_until < current_time)
 558                 return FALSE;
 559
 560         return TRUE;
 561 }
 562
 563 /*
 564  * remove stale cached entries so that they can be refreshed
 565  */
 566 static void cache_enforce_validity(struct cache_entry *entry)
 567 {
 568         time_t current_time = time(0);
 569
 570         if (cache_check_is_valid(entry->ipv4, current_time) == FALSE
 571                                                         && entry->ipv4) {
 572                 DBG("cache timeout \"%s\" type A", entry->key);
 573                 g_free(entry->ipv4->data);
 574                 g_free(entry->ipv4);
 575                 entry->ipv4 = NULL;
 576
 577         }
 578
 579         if (cache_check_is_valid(entry->ipv6, current_time) == FALSE
 580                                                         && entry->ipv6) {
 581                 DBG("cache timeout \"%s\" type AAAA", entry->key);
 582                 g_free(entry->ipv6->data);
 583                 g_free(entry->ipv6);
 584                 entry->ipv6 = NULL;
 585         }
 586 }
 587
 588 static uint16_t cache_check_validity(char *question, uint16_t type,
 589                                 struct cache_entry *entry)
 590 {
 591         time_t current_time = time(0);
 592         int want_refresh = 0;
 593
 594         /*
 595          * if we have a popular entry, we want a refresh instead of
 596          * total destruction of the entry.
 597          */
 598         if (entry->hits > 2)
 599                 want_refresh = 1;
 600
 601         cache_enforce_validity(entry);
 602
 603         switch (type) {
 604         case 1:         /* IPv4 */
 605                 if (cache_check_is_valid(entry->ipv4, current_time) == FALSE) {
 606                         DBG("cache %s \"%s\" type A", entry->ipv4 ?
 607                                         "timeout" : "entry missing", question);
 608
 609                         if (want_refresh)
 610                                 entry->want_refresh = 1;
 611
 612                         /*
 613                          * We do not remove cache entry if there is still
 614                          * valid IPv6 entry found in the cache.
 615                          */
 616                         if (cache_check_is_valid(entry->ipv6, current_time)
 617                                         == FALSE && want_refresh == FALSE) {
 618                                 g_hash_table_remove(cache, question);
 619                                 type = 0;
 620                         }
 621                 }
 622                 break;
 623
 624         case 28:        /* IPv6 */
 625                 if (cache_check_is_valid(entry->ipv6, current_time) == FALSE) {
 626                         DBG("cache %s \"%s\" type AAAA", entry->ipv6 ?
 627                                         "timeout" : "entry missing", question);
 628
 629                         if (want_refresh)
 630                                 entry->want_refresh = 1;
 631
 632                         if (cache_check_is_valid(entry->ipv4, current_time)
 633                                         == FALSE && want_refresh == FALSE) {
 634                                 g_hash_table_remove(cache, question);
 635                                 type = 0;
 636                         }
 637                 }
 638                 break;
 639         }
 640
 641         return type;
 642 }
 643
 644 static struct cache_entry *cache_check(gpointer request, int *qtype)
 645 {
 646         char *question = request + 12;
 647         struct cache_entry *entry;
 648         struct domain_question *q;
 649         uint16_t type;
 650         int offset;
 651
 652         offset = strlen(question) + 1;
 653         q = (void *) (question + offset);
 654         type = ntohs(q->type);
 655
 656         /* We only cache either A (1) or AAAA (28) requests */
 657         if (type != 1 && type != 28)
 658                 return NULL;
 659
 660         entry = g_hash_table_lookup(cache, question);
 661         if (entry == NULL)
 662                 return NULL;
 663
 664         type = cache_check_validity(question, type, entry);
 665         if (type == 0)
 666                 return NULL;
 667
 668         *qtype = type;
 669         return entry;
 670 }
 671
 672 /*
 673  * Get a label/name from DNS resource record. The function decompresses the
 674  * label if necessary. The function does not convert the name to presentation
 675  * form. This means that the result string will contain label lengths instead
 676  * of dots between labels. We intentionally do not want to convert to dotted
 677  * format so that we can cache the wire format string directly.
 678  */
 679 static int get_name(int counter,
 680                 unsigned char *pkt, unsigned char *start, unsigned char *max,
 681                 unsigned char *output, int output_max, int *output_len,
 682                 unsigned char **end, char *name, int *name_len)
 683 {
 684         unsigned char *p;
 685
 686         /* Limit recursion to 10 (this means up to 10 labels in domain name) */
 687         if (counter > 10)
 688                 return -EINVAL;
 689
 690         p = start;
 691         while (*p) {
 692                 if ((*p & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
 693                         uint16_t offset = (*p & 0x3F) * 256 + *(p + 1);
 694
 695                         if (offset >= max - pkt)
 696                                 return -ENOBUFS;
 697
 698                         if (*end == NULL)
 699                                 *end = p + 2;
 700
 701                         return get_name(counter + 1, pkt, pkt + offset, max,
 702                                         output, output_max, output_len, end,
 703                                         name, name_len);
 704                 } else {
 705                         unsigned label_len = *p;
 706
 707                         if (pkt + label_len > max)
 708                                 return -ENOBUFS;
 709
 710                         if (*output_len > output_max)
 711                                 return -ENOBUFS;
 712
 713                         /*
 714                          * We need the original name in order to check
 715                          * if this answer is the correct one.
 716                          */
 717                         name[(*name_len)++] = label_len;
 718                         memcpy(name + *name_len, p + 1, label_len + 1);
 719                         *name_len += label_len;
 720
 721                         /* We compress the result */
 722                         output[0] = NS_CMPRSFLGS;
 723                         output[1] = 0x0C;
 724                         *output_len = 2;
 725
 726                         p += label_len + 1;
 727
 728                         if (*end == NULL)
 729                                 *end = p;
 730
 731                         if (p >= max)
 732                                 return -ENOBUFS;
 733                 }
 734         }
 735
 736         return 0;
 737 }
 738
 739 static int parse_rr(unsigned char *buf, unsigned char *start,
 740                         unsigned char *max,
 741                         unsigned char *response, unsigned int *response_size,
 742                         uint16_t *type, uint16_t *class, int *ttl, int *rdlen,
 743                         unsigned char **end,
 744                         char *name)
 745 {
 746         struct domain_rr *rr;
 747         int err, offset;
 748         int name_len = 0, output_len = 0, max_rsp = *response_size;
 749
 750         err = get_name(0, buf, start, max, response, max_rsp,
 751                 &output_len, end, name, &name_len);
 752         if (err < 0)
 753                 return err;
 754
 755         offset = output_len;
 756
 757         if ((unsigned int) offset > *response_size)
 758                 return -ENOBUFS;
 759
 760         rr = (void *) (*end);
 761
 762         if (rr == NULL)
 763                 return -EINVAL;
 764
 765         *type = ntohs(rr->type);
 766         *class = ntohs(rr->class);
 767         *ttl = ntohl(rr->ttl);
 768         *rdlen = ntohs(rr->rdlen);
 769
 770         if (*ttl < 0)
 771                 return -EINVAL;
 772
 773         memcpy(response + offset, *end, sizeof(struct domain_rr));
 774
 775         offset += sizeof(struct domain_rr);
 776         *end += sizeof(struct domain_rr);
 777
 778         if ((unsigned int) (offset + *rdlen) > *response_size)
 779                 return -ENOBUFS;
 780
 781         memcpy(response + offset, *end, *rdlen);
 782
 783         *end += *rdlen;
 784
 785         *response_size = offset + *rdlen;
 786
 787         return 0;
 788 }
 789
 790 static gboolean check_alias(GSList *aliases, char *name)
 791 {
 792         GSList *list;
 793
 794         if (aliases != NULL) {
 795                 for (list = aliases; list; list = list->next) {
 796                         int len = strlen((char *)list->data);
 797                         if (strncmp((char *)list->data, name, len) == 0)
 798                                 return TRUE;
 799                 }
 800         }
 801
 802         return FALSE;
 803 }
 804
 805 static int parse_response(unsigned char *buf, int buflen,
 806                         char *question, int qlen,
 807                         uint16_t *type, uint16_t *class, int *ttl,
 808                         unsigned char *response, unsigned int *response_len,
 809                         uint16_t *answers)
 810 {
 811         struct domain_hdr *hdr = (void *) buf;
 812         struct domain_question *q;
 813         unsigned char *ptr;
 814         uint16_t qdcount = ntohs(hdr->qdcount);
 815         uint16_t ancount = ntohs(hdr->ancount);
 816         int err, i;
 817         uint16_t qtype, qclass;
 818         unsigned char *next = NULL;
 819         unsigned int maxlen = *response_len;
 820         GSList *aliases = NULL, *list;
 821         char name[NS_MAXDNAME + 1];
 822
 823         if (buflen < 12)
 824                 return -EINVAL;
 825
 826         DBG("qr %d qdcount %d", hdr->qr, qdcount);
 827
 828         /* We currently only cache responses where question count is 1 */
 829         if (hdr->qr != 1 || qdcount != 1)
 830                 return -EINVAL;
 831
 832         ptr = buf + sizeof(struct domain_hdr);
 833
 834         strncpy(question, (char *) ptr, qlen);
 835         qlen = strlen(question);
 836         ptr += qlen + 1; /* skip \0 */
 837
 838         q = (void *) ptr;
 839         qtype = ntohs(q->type);
 840
 841         /* We cache only A and AAAA records */
 842         if (qtype != 1 && qtype != 28)
 843                 return -ENOMSG;
 844
 845         qclass = ntohs(q->class);
 846
 847         ptr += 2 + 2; /* ptr points now to answers */
 848
 849         err = -ENOMSG;
 850         *response_len = 0;
 851         *answers = 0;
 852
 853         /*
 854          * We have a bunch of answers (like A, AAAA, CNAME etc) to
 855          * A or AAAA question. We traverse the answers and parse the
 856          * resource records. Only A and AAAA records are cached, all
 857          * the other records in answers are skipped.
 858          */
 859         for (i = 0; i < ancount; i++) {
 860                 /*
 861                  * Get one address at a time to this buffer.
 862                  * The max size of the answer is
 863                  *   2 (pointer) + 2 (type) + 2 (class) +
 864                  *   4 (ttl) + 2 (rdlen) + addr (16 or 4) = 28
 865                  * for A or AAAA record.
 866                  * For CNAME the size can be bigger.
 867                  */
 868                 unsigned char rsp[NS_MAXCDNAME];
 869                 unsigned int rsp_len = sizeof(rsp) - 1;
 870                 int ret, rdlen;
 871
 872                 memset(rsp, 0, sizeof(rsp));
 873
 874                 ret = parse_rr(buf, ptr, buf + buflen, rsp, &rsp_len,
 875                         type, class, ttl, &rdlen, &next, name);
 876                 if (ret != 0) {
 877                         err = ret;
 878                         goto out;
 879                 }
 880
 881                 /*
 882                  * Now rsp contains compressed or uncompressed resource
 883                  * record. Next we check if this record answers the question.
 884                  * The name var contains the uncompressed label.
 885                  * One tricky bit is the CNAME records as they alias
 886                  * the name we might be interested in.
 887                  */
 888
 889                 /*
 890                  * Go to next answer if the class is not the one we are
 891                  * looking for.
 892                  */
 893                 if (*class != qclass) {
 894                         ptr = next;
 895                         next = NULL;
 896                         continue;
 897                 }
 898
 899                 /*
 900                  * Try to resolve aliases also, type is CNAME(5).
 901                  * This is important as otherwise the aliased names would not
 902                  * be cached at all as the cache would not contain the aliased
 903                  * question.
 904                  *
 905                  * If any CNAME is found in DNS packet, then we cache the alias
 906                  * IP address instead of the question (as the server
 907                  * said that question has only an alias).
 908                  * This means in practice that if e.g., ipv6.google.com is
 909                  * queried, DNS server returns CNAME of that name which is
 910                  * ipv6.l.google.com. We then cache the address of the CNAME
 911                  * but return the question name to client. So the alias
 912                  * status of the name is not saved in cache and thus not
 913                  * returned to the client. We do not return DNS packets from
 914                  * cache to client saying that ipv6.google.com is an alias to
 915                  * ipv6.l.google.com but we return instead a DNS packet that
 916                  * says ipv6.google.com has address xxx which is in fact the
 917                  * address of ipv6.l.google.com. For caching purposes this
 918                  * should not cause any issues.
 919                  */
 920                 if (*type == 5 && strncmp(question, name, qlen) == 0) {
 921                         /*
 922                          * So now the alias answered the question. This is
 923                          * not very useful from caching point of view as
 924                          * the following A or AAAA records will not match the
 925                          * question. We need to find the real A/AAAA record
 926                          * of the alias and cache that.
 927                          */
 928                         unsigned char *end = NULL;
 929                         int name_len = 0, output_len;
 930
 931                         memset(rsp, 0, sizeof(rsp));
 932                         rsp_len = sizeof(rsp) - 1;
 933
 934                         /*
 935                          * Alias is in rdata part of the message,
 936                          * and next-rdlen points to it. So we need to get
 937                          * the real name of the alias.
 938                          */
 939                         ret = get_name(0, buf, next - rdlen, buf + buflen,
 940                                         rsp, rsp_len, &output_len, &end,
 941                                         name, &name_len);
 942                         if (ret != 0) {
 943                                 /* just ignore the error at this point */
 944                                 ptr = next;
 945                                 next = NULL;
 946                                 continue;
 947                         }
 948
 949                         /*
 950                          * We should now have the alias of the entry we might
 951                          * want to cache. Just remember it for a while.
 952                          * We check the alias list when we have parsed the
 953                          * A or AAAA record.
 954                          */
 955                         aliases = g_slist_prepend(aliases, g_strdup(name));
 956
 957                         ptr = next;
 958                         next = NULL;
 959                         continue;
 960                 }
 961
 962                 if (*type == qtype) {
 963                         /*
 964                          * We found correct type (A or AAAA)
 965                          */
 966                         if (check_alias(aliases, name) == TRUE ||
 967                                 (aliases == NULL && strncmp(question, name,
 968                                                         qlen) == 0)) {
 969                                 /*
 970                                  * We found an alias or the name of the rr
 971                                  * matches the question. If so, we append
 972                                  * the compressed label to the cache.
 973                                  * The end result is a response buffer that
 974                                  * will contain one or more cached and
 975                                  * compressed resource records.
 976                                  */
 977                                 if (*response_len + rsp_len > maxlen) {
 978                                         err = -ENOBUFS;
 979                                         goto out;
 980                                 }
 981                                 memcpy(response + *response_len, rsp, rsp_len);
 982                                 *response_len += rsp_len;
 983                                 (*answers)++;
 984                                 err = 0;
 985                         }
 986                 }
 987
 988                 ptr = next;
 989                 next = NULL;
 990         }
 991
 992 out:
 993         for (list = aliases; list; list = list->next)
 994                 g_free(list->data);
 995         g_slist_free(aliases);
 996
 997         return err;
 998 }
 999
1000 struct cache_timeout {
1001         time_t current_time;
1002         int max_timeout;
1003         int try_harder;
1004 };
1005
1006 static gboolean cache_check_entry(gpointer key, gpointer value,
1007                                         gpointer user_data)
1008 {
1009         struct cache_timeout *data = user_data;
1010         struct cache_entry *entry = value;
1011         int max_timeout;
1012
1013         /* Scale the number of hits by half as part of cache aging */
1014
1015         entry->hits /= 2;
1016
1017         /*
1018          * If either IPv4 or IPv6 cached entry has expired, we
1019          * remove both from the cache.
1020          */
1021
1022         if (entry->ipv4 != NULL && entry->ipv4->timeout > 0) {
1023                 max_timeout = entry->ipv4->cache_until;
1024                 if (max_timeout > data->max_timeout)
1025                         data->max_timeout = max_timeout;
1026
1027                 if (entry->ipv4->cache_until < data->current_time)
1028                         return TRUE;
1029         }
1030
1031         if (entry->ipv6 != NULL && entry->ipv6->timeout > 0) {
1032                 max_timeout = entry->ipv6->cache_until;
1033                 if (max_timeout > data->max_timeout)
1034                         data->max_timeout = max_timeout;
1035
1036                 if (entry->ipv6->cache_until < data->current_time)
1037                         return TRUE;
1038         }
1039
1040         /*
1041          * if we're asked to try harder, also remove entries that have
1042          * few hits
1043          */
1044         if (data->try_harder && entry->hits < 4)
1045                 return TRUE;
1046
1047         return FALSE;
1048 }
1049
1050 static void cache_cleanup(void)
1051 {
1052         static int max_timeout;
1053         struct cache_timeout data;
1054         int count = 0;
1055
1056         data.current_time = time(0);
1057         data.max_timeout = 0;
1058         data.try_harder = 0;
1059
1060         /*
1061          * In the first pass, we only remove entries that have timed out.
1062          * We use a cache of the first time to expire to do this only
1063          * when it makes sense.
1064          */
1065         if (max_timeout <= data.current_time) {
1066                 count = g_hash_table_foreach_remove(cache, cache_check_entry,
1067                                                 &data);
1068         }
1069         DBG("removed %d in the first pass", count);
1070
1071         /*
1072          * In the second pass, if the first pass turned up blank,
1073          * we also expire entries with a low hit count,
1074          * while aging the hit count at the same time.
1075          */
1076         data.try_harder = 1;
1077         if (count == 0)
1078                 count = g_hash_table_foreach_remove(cache, cache_check_entry,
1079                                                 &data);
1080
1081         if (count == 0)
1082                 /*
1083                  * If we could not remove anything, then remember
1084                  * what is the max timeout and do nothing if we
1085                  * have not yet reached it. This will prevent
1086                  * constant traversal of the cache if it is full.
1087                  */
1088                 max_timeout = data.max_timeout;
1089         else
1090                 max_timeout = 0;
1091 }
1092
1093 static gboolean cache_invalidate_entry(gpointer key, gpointer value,
1094                                         gpointer user_data)
1095 {
1096         struct cache_entry *entry = value;
1097
1098         /* first, delete any expired elements */
1099         cache_enforce_validity(entry);
1100
1101         /* if anything is not expired, mark the entry for refresh */
1102         if (entry->hits > 0 && (entry->ipv4 || entry->ipv6))
1103                 entry->want_refresh = 1;
1104
1105         /* delete the cached data */
1106         if (entry->ipv4) {
1107                 g_free(entry->ipv4->data);
1108                 g_free(entry->ipv4);
1109                 entry->ipv4 = NULL;
1110         }
1111
1112         if (entry->ipv6) {
1113                 g_free(entry->ipv6->data);
1114                 g_free(entry->ipv6);
1115                 entry->ipv6 = NULL;
1116         }
1117
1118         /* keep the entry if we want it refreshed, delete it otherwise */
1119         if (entry->want_refresh)
1120                 return FALSE;
1121         else
1122                 return TRUE;
1123 }
1124
1125 /*
1126  * cache_invalidate is called from places where the DNS landscape
1127  * has changed, say because connections are added or we entered a VPN.
1128  * The logic is to wipe all cache data, but mark all non-expired
1129  * parts of the cache for refresh rather than deleting the whole cache.
1130  */
1131 static void cache_invalidate(void)
1132 {
1133         DBG("Invalidating the DNS cache");
1134          g_hash_table_foreach_remove(cache, cache_invalidate_entry,
1135                                                 NULL);
1136 }
1137
1138 static void cache_refresh_entry(struct cache_entry *entry)
1139 {
1140
1141         cache_enforce_validity(entry);
1142
1143         if (entry->hits > 2 && entry->ipv4 == NULL)
1144                 entry->want_refresh = 1;
1145         if (entry->hits > 2 && entry->ipv6 == NULL)
1146                 entry->want_refresh = 1;
1147
1148         if (entry->want_refresh) {
1149                 char *c;
1150                 char dns_name[NS_MAXDNAME + 1];
1151                 entry->want_refresh = 0;
1152
1153                 /* turn a DNS name into a hostname with dots */
1154                 strncpy(dns_name, entry->key, NS_MAXDNAME);
1155                 c = dns_name;
1156                 while (c && *c) {
1157                         int jump;
1158                         jump = *c;
1159                         *c = '.';
1160                         c += jump + 1;
1161                 }
1162                 DBG("Refreshing %s\n", dns_name);
1163                 /* then refresh the hostname */
1164                 refresh_dns_entry(entry, &dns_name[1]);
1165         }
1166 }
1167
1168 static void cache_refresh_iterator(gpointer key, gpointer value,
1169                                         gpointer user_data)
1170 {
1171         struct cache_entry *entry = value;
1172
1173         cache_refresh_entry(entry);
1174 }
1175
1176 static void cache_refresh(void)
1177 {
1178         g_hash_table_foreach(cache, cache_refresh_iterator, NULL);
1179 }
1180
1181
1182
1183 static int reply_query_type(unsigned char *msg, int len)
1184 {
1185         unsigned char *c;
1186         uint16_t *w;
1187         int l;
1188         int type;
1189
1190         /* skip the header */
1191         c = msg + sizeof(struct domain_hdr);
1192         len -= sizeof(struct domain_hdr);
1193
1194         if (len < 0)
1195                 return 0;
1196
1197         /* now the query, which is a name and 2 16 bit words */
1198         l = dns_name_length(c) + 1;
1199         c += l;
1200         len -= l;
1201         w = (uint16_t *) c;
1202         type = ntohs(*w);
1203         return type;
1204 }
1205
1206 static int cache_update(struct server_data *srv, unsigned char *msg,
1207                         unsigned int msg_len)
1208 {
1209         int offset = protocol_offset(srv->protocol);
1210         int err, qlen, ttl = 0;
1211         uint16_t answers = 0, type = 0, class = 0;
1212         struct domain_question *q;
1213         struct cache_entry *entry;
1214         struct cache_data *data;
1215         char question[NS_MAXDNAME + 1];
1216         unsigned char response[NS_MAXDNAME + 1];
1217         unsigned char *ptr;
1218         unsigned int rsplen;
1219         gboolean new_entry = TRUE;
1220         time_t current_time;
1221
1222         if (cache_size >= MAX_CACHE_SIZE) {
1223                 cache_cleanup();
1224                 if (cache_size >= MAX_CACHE_SIZE)
1225                         return 0;
1226         }
1227
1228         current_time = time(0);
1229
1230         /* don't do a cache refresh more than twice a minute */
1231         if (next_refresh < current_time) {
1232                 cache_refresh();
1233                 next_refresh = current_time + 30;
1234         }
1235
1236
1237         /* Continue only if response code is 0 (=ok) */
1238         if (msg[3] & 0x0f)
1239                 return 0;
1240
1241         if (offset < 0)
1242                 return 0;
1243
1244         rsplen = sizeof(response) - 1;
1245         question[sizeof(question) - 1] = '\0';
1246
1247         err = parse_response(msg + offset, msg_len - offset,
1248                                 question, sizeof(question) - 1,
1249                                 &type, &class, &ttl,
1250                                 response, &rsplen, &answers);
1251
1252         /*
1253          * special case: if we do a ipv6 lookup and get no result
1254          * for a record that's already in our ipv4 cache.. we want
1255          * to cache the negative response.
1256          */
1257         if ((err == -ENOMSG || err == -ENOBUFS) &&
1258                         reply_query_type(msg, msg_len) == 28) {
1259                 entry = g_hash_table_lookup(cache, question);
1260                 if (entry && entry->ipv4 && entry->ipv6 == NULL) {
1261                         data = g_try_new(struct cache_data, 1);
1262                         if (data == NULL)
1263                                 return -ENOMEM;
1264                         data->inserted = entry->ipv4->inserted;
1265                         data->type = type;
1266                         data->answers = msg[5];
1267                         data->timeout = entry->ipv4->timeout;
1268                         data->data_len = msg_len;
1269                         data->data = ptr = g_malloc(msg_len);
1270                         data->valid_until = entry->ipv4->valid_until;
1271                         data->cache_until = entry->ipv4->cache_until;
1272                         memcpy(data->data, msg, msg_len);
1273                         entry->ipv6 = data;
1274                         /*
1275                          * we will get a "hit" when we serve the response
1276                          * out of the cache
1277                          */
1278                         entry->hits--;
1279                         if (entry->hits < 0)
1280                                 entry->hits = 0;
1281                         return 0;
1282                 }
1283         }
1284
1285         if (err < 0 || ttl == 0)
1286                 return 0;
1287
1288         qlen = strlen(question);
1289
1290         /*
1291          * If the cache contains already data, check if the
1292          * type of the cached data is the same and do not add
1293          * to cache if data is already there.
1294          * This is needed so that we can cache both A and AAAA
1295          * records for the same name.
1296          */
1297         entry = g_hash_table_lookup(cache, question);
1298         if (entry == NULL) {
1299                 entry = g_try_new(struct cache_entry, 1);
1300                 if (entry == NULL)
1301                         return -ENOMEM;
1302
1303                 data = g_try_new(struct cache_data, 1);
1304                 if (data == NULL) {
1305                         g_free(entry);
1306                         return -ENOMEM;
1307                 }
1308
1309                 entry->key = g_strdup(question);
1310                 entry->ipv4 = entry->ipv6 = NULL;
1311                 entry->want_refresh = 0;
1312                 entry->hits = 0;
1313
1314                 if (type == 1)
1315                         entry->ipv4 = data;
1316                 else
1317                         entry->ipv6 = data;
1318         } else {
1319                 if (type == 1 && entry->ipv4 != NULL)
1320                         return 0;
1321
1322                 if (type == 28 && entry->ipv6 != NULL)
1323                         return 0;
1324
1325                 data = g_try_new(struct cache_data, 1);
1326                 if (data == NULL)
1327                         return -ENOMEM;
1328
1329                 if (type == 1)
1330                         entry->ipv4 = data;
1331                 else
1332                         entry->ipv6 = data;
1333
1334                 /*
1335                  * compensate for the hit we'll get for serving
1336                  * the response out of the cache
1337                  */
1338                 entry->hits--;
1339                 if (entry->hits < 0)
1340                         entry->hits = 0;
1341
1342                 new_entry = FALSE;
1343         }
1344
1345         if (ttl < MIN_CACHE_TTL)
1346                 ttl = MIN_CACHE_TTL;
1347
1348         data->inserted = current_time;
1349         data->type = type;
1350         data->answers = answers;
1351         data->timeout = ttl;
1352         data->data_len = 12 + qlen + 1 + 2 + 2 + rsplen;
1353         data->data = ptr = g_malloc(data->data_len);
1354         data->valid_until = current_time + ttl;
1355
1356         /*
1357          * Restrict the cached DNS record TTL to some sane value
1358          * in order to prevent data staying in the cache too long.
1359          */
1360         if (ttl > MAX_CACHE_TTL)
1361                 ttl = MAX_CACHE_TTL;
1362
1363         data->cache_until = round_down_ttl(current_time + ttl, ttl);
1364
1365         if (data->data == NULL) {
1366                 g_free(entry->key);
1367                 g_free(data);
1368                 g_free(entry);
1369                 return -ENOMEM;
1370         }
1371
1372         memcpy(ptr, msg, 12);
1373         memcpy(ptr + 12, question, qlen + 1); /* copy also the \0 */
1374
1375         q = (void *) (ptr + 12 + qlen + 1);
1376         q->type = htons(type);
1377         q->class = htons(class);
1378         memcpy(ptr + 12 + qlen + 1 + sizeof(struct domain_question),
1379                 response, rsplen);
1380
1381         if (new_entry == TRUE) {
1382                 g_hash_table_replace(cache, entry->key, entry);
1383                 cache_size++;
1384         }
1385
1386         DBG("cache %d %squestion \"%s\" type %d ttl %d size %zd",
1387                 cache_size, new_entry ? "new " : "old ",
1388                 question, type, ttl,
1389                 sizeof(*entry) + sizeof(*data) + data->data_len + qlen);
1390
1391         return 0;
1392 }
1393
1394 static int ns_resolv(struct server_data *server, struct request_data *req,
1395                                 gpointer request, gpointer name)
1396 {
1397         GList *list;
1398         int sk, err, type = 0;
1399         char *dot, *lookup = (char *) name;
1400         struct cache_entry *entry;
1401
1402         entry = cache_check(request, &type);
1403         if (entry != NULL) {
1404                 int ttl_left = 0;
1405                 struct cache_data *data;
1406
1407                 DBG("cache hit %s type %s", lookup, type == 1 ? "A" : "AAAA");
1408                 if (type == 1)
1409                         data = entry->ipv4;
1410                 else
1411                         data = entry->ipv6;
1412
1413                 if (data) {
1414                         ttl_left = data->valid_until - time(0);
1415                         entry->hits++;
1416                 }
1417
1418                 if (data != NULL && req->protocol == IPPROTO_TCP) {
1419                         send_cached_response(req->client_sk, data->data,
1420                                         data->data_len, NULL, 0, IPPROTO_TCP,
1421                                         req->srcid, data->answers, ttl_left);
1422                         return 1;
1423                 }
1424
1425                 if (data != NULL && req->protocol == IPPROTO_UDP) {
1426                         int sk;
1427                         sk = g_io_channel_unix_get_fd(
1428                                         req->ifdata->udp_listener_channel);
1429
1430                         send_cached_response(sk, data->data,
1431                                 data->data_len, &req->sa, req->sa_len,
1432                                 IPPROTO_UDP, req->srcid, data->answers,
1433                                 ttl_left);
1434                         return 1;
1435                 }
1436         }
1437
1438         sk = g_io_channel_unix_get_fd(server->channel);
1439
1440         err = send(sk, request, req->request_len, 0);
1441
1442         req->numserv++;
1443
1444         /* If we have more than one dot, we don't add domains */
1445         dot = strchr(lookup, '.');
1446         if (dot != NULL && dot != lookup + strlen(lookup) - 1)
1447                 return 0;
1448
1449         if (server->domains != NULL && server->domains->data != NULL)
1450                 req->append_domain = TRUE;
1451
1452         for (list = server->domains; list; list = list->next) {
1453                 char *domain;
1454                 unsigned char alt[1024];
1455                 struct domain_hdr *hdr = (void *) &alt;
1456                 int altlen, domlen, offset;
1457
1458                 domain = list->data;
1459
1460                 if (domain == NULL)
1461                         continue;
1462
1463                 offset = protocol_offset(server->protocol);
1464                 if (offset < 0)
1465                         return offset;
1466
1467                 domlen = strlen(domain) + 1;
1468                 if (domlen < 5)
1469                         return -EINVAL;
1470
1471                 alt[offset] = req->altid & 0xff;
1472                 alt[offset + 1] = req->altid >> 8;
1473
1474                 memcpy(alt + offset + 2, request + offset + 2, 10);
1475                 hdr->qdcount = htons(1);
1476
1477                 altlen = append_query(alt + offset + 12, sizeof(alt) - 12,
1478                                         name, domain);
1479                 if (altlen < 0)
1480                         return -EINVAL;
1481
1482                 altlen += 12;
1483
1484                 memcpy(alt + offset + altlen,
1485                         request + offset + altlen - domlen,
1486                                 req->request_len - altlen - offset + domlen);
1487
1488                 if (server->protocol == IPPROTO_TCP) {
1489                         int req_len = req->request_len + domlen - 2;
1490
1491                         alt[0] = (req_len >> 8) & 0xff;
1492                         alt[1] = req_len & 0xff;
1493                 }
1494
1495                 err = send(sk, alt, req->request_len + domlen, 0);
1496                 if (err < 0)
1497                         return -EIO;
1498
1499                 req->numserv++;
1500         }
1501
1502         return 0;
1503 }
1504
1505 static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol,
1506                                 struct server_data *data)
1507 {
1508         struct domain_hdr *hdr;
1509         struct request_data *req;
1510         int dns_id, sk, err, offset = protocol_offset(protocol);
1511         struct listener_data *ifdata;
1512
1513         if (offset < 0)
1514                 return offset;
1515
1516         hdr = (void *)(reply + offset);
1517         dns_id = reply[offset] | reply[offset + 1] << 8;
1518
1519         DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id);
1520
1521         req = find_request(dns_id);
1522         if (req == NULL)
1523                 return -EINVAL;
1524
1525         DBG("id 0x%04x rcode %d", hdr->id, hdr->rcode);
1526
1527         ifdata = req->ifdata;
1528
1529         reply[offset] = req->srcid & 0xff;
1530         reply[offset + 1] = req->srcid >> 8;
1531
1532         req->numresp++;
1533
1534         if (hdr->rcode == 0 || req->resp == NULL) {
1535
1536                 /*
1537                  * If the domain name was append
1538                  * remove it before forwarding the reply.
1539                  */
1540                 if (req->append_domain == TRUE) {
1541                         unsigned char *ptr;
1542                         uint8_t host_len;
1543                         unsigned int domain_len;
1544
1545                         /*
1546                          * ptr points to the first char of the hostname.
1547                          * ->hostname.domain.net
1548                          */
1549                         ptr = reply + offset + sizeof(struct domain_hdr);
1550                         host_len = *ptr;
1551                         domain_len = strlen((const char *)ptr) - host_len - 1;
1552
1553                         /*
1554                          * remove the domain name and replaced it by the end
1555                          * of reply.
1556                          */
1557                         memmove(ptr + host_len + 1,
1558                                 ptr + host_len + domain_len + 1,
1559                                 reply_len - (ptr - reply + domain_len));
1560
1561                         reply_len = reply_len - domain_len;
1562                 }
1563
1564                 g_free(req->resp);
1565                 req->resplen = 0;
1566
1567                 req->resp = g_try_malloc(reply_len);
1568                 if (req->resp == NULL)
1569                         return -ENOMEM;
1570
1571                 memcpy(req->resp, reply, reply_len);
1572                 req->resplen = reply_len;
1573
1574                 cache_update(data, reply, reply_len);
1575         }
1576
1577         if (hdr->rcode > 0 && req->numresp < req->numserv)
1578                 return -EINVAL;
1579
1580         if (req->timeout > 0)
1581                 g_source_remove(req->timeout);
1582
1583         request_list = g_slist_remove(request_list, req);
1584
1585         if (protocol == IPPROTO_UDP) {
1586                 sk = g_io_channel_unix_get_fd(ifdata->udp_listener_channel);
1587                 err = sendto(sk, req->resp, req->resplen, 0,
1588                              &req->sa, req->sa_len);
1589         } else {
1590                 sk = req->client_sk;
1591                 err = send(sk, req->resp, req->resplen, 0);
1592                 close(sk);
1593         }
1594
1595         g_free(req->resp);
1596         g_free(req);
1597
1598         return err;
1599 }
1600
1601 static void cache_element_destroy(gpointer value)
1602 {
1603         struct cache_entry *entry = value;
1604
1605         if (entry == NULL)
1606                 return;
1607
1608         if (entry->ipv4 != NULL) {
1609                 g_free(entry->ipv4->data);
1610                 g_free(entry->ipv4);
1611         }
1612
1613         if (entry->ipv6 != NULL) {
1614                 g_free(entry->ipv6->data);
1615                 g_free(entry->ipv6);
1616         }
1617
1618         g_free(entry->key);
1619         g_free(entry);
1620
1621         if (--cache_size < 0)
1622                 cache_size = 0;
1623 }
1624
1625 static void destroy_server(struct server_data *server)
1626 {
1627         GList *list;
1628
1629         DBG("interface %s server %s", server->interface, server->server);
1630
1631         server_list = g_slist_remove(server_list, server);
1632
1633         if (server->watch > 0)
1634                 g_source_remove(server->watch);
1635
1636         if (server->timeout > 0)
1637                 g_source_remove(server->timeout);
1638
1639         g_io_channel_unref(server->channel);
1640
1641         if (server->protocol == IPPROTO_UDP)
1642                 connman_info("Removing DNS server %s", server->server);
1643
1644         g_free(server->incoming_reply);
1645         g_free(server->server);
1646         for (list = server->domains; list; list = list->next) {
1647                 char *domain = list->data;
1648
1649                 server->domains = g_list_remove(server->domains, domain);
1650                 g_free(domain);
1651         }
1652         g_free(server->interface);
1653
1654         if (__sync_fetch_and_sub(&cache_refcount, 1) == 1)
1655                 g_hash_table_destroy(cache);
1656
1657         g_free(server);
1658 }
1659
1660 static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition,
1661                                                         gpointer user_data)
1662 {
1663         unsigned char buf[4096];
1664         int sk, err, len;
1665         struct server_data *data = user_data;
1666
1667         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1668                 connman_error("Error with UDP server %s", data->server);
1669                 data->watch = 0;
1670                 return FALSE;
1671         }
1672
1673         sk = g_io_channel_unix_get_fd(channel);
1674
1675         len = recv(sk, buf, sizeof(buf), 0);
1676         if (len < 12)
1677                 return TRUE;
1678
1679         err = forward_dns_reply(buf, len, IPPROTO_UDP, data);
1680         if (err < 0)
1681                 return TRUE;
1682
1683         return TRUE;
1684 }
1685
1686 static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition,
1687                                                         gpointer user_data)
1688 {
1689         int sk;
1690         struct server_data *server = user_data;
1691
1692         sk = g_io_channel_unix_get_fd(channel);
1693         if (sk == 0)
1694                 return FALSE;
1695
1696         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1697                 GSList *list;
1698 hangup:
1699                 DBG("TCP server channel closed");
1700
1701                 /*
1702                  * Discard any partial response which is buffered; better
1703                  * to get a proper response from a working server.
1704                  */
1705                 g_free(server->incoming_reply);
1706                 server->incoming_reply = NULL;
1707
1708                 for (list = request_list; list; list = list->next) {
1709                         struct request_data *req = list->data;
1710                         struct domain_hdr *hdr;
1711
1712                         if (req->protocol == IPPROTO_UDP)
1713                                 continue;
1714
1715                         if (req->request == NULL)
1716                                 continue;
1717
1718                         /*
1719                          * If we're not waiting for any further response
1720                          * from another name server, then we send an error
1721                          * response to the client.
1722                          */
1723                         if (req->numserv && --(req->numserv))
1724                                 continue;
1725
1726                         hdr = (void *) (req->request + 2);
1727                         hdr->id = req->srcid;
1728                         send_response(req->client_sk, req->request,
1729                                 req->request_len, NULL, 0, IPPROTO_TCP);
1730
1731                         request_list = g_slist_remove(request_list, req);
1732                 }
1733
1734                 destroy_server(server);
1735
1736                 return FALSE;
1737         }
1738
1739         if ((condition & G_IO_OUT) && !server->connected) {
1740                 GSList *list;
1741                 GList *domains;
1742                 struct server_data *udp_server;
1743
1744                 udp_server = find_server(server->interface, server->server,
1745                                                                 IPPROTO_UDP);
1746                 if (udp_server != NULL) {
1747                         for (domains = udp_server->domains; domains;
1748                                                 domains = domains->next) {
1749                                 char *dom = domains->data;
1750
1751                                 DBG("Adding domain %s to %s",
1752                                                 dom, server->server);
1753
1754                                 server->domains = g_list_append(server->domains,
1755                                                                 g_strdup(dom));
1756                         }
1757                 }
1758
1759                 server->connected = TRUE;
1760                 server_list = g_slist_append(server_list, server);
1761
1762                 if (server->timeout > 0) {
1763                         g_source_remove(server->timeout);
1764                         server->timeout = 0;
1765                 }
1766
1767                 for (list = request_list; list; list = list->next) {
1768                         struct request_data *req = list->data;
1769
1770                         if (req->protocol == IPPROTO_UDP)
1771                                 continue;
1772
1773                         DBG("Sending req %s over TCP", (char *)req->name);
1774
1775                         if (req->timeout > 0)
1776                                 g_source_remove(req->timeout);
1777
1778                         req->timeout = g_timeout_add_seconds(30,
1779                                                 request_timeout, req);
1780                         if (ns_resolv(server, req, req->request,
1781                                         req->name) > 0) {
1782                                 /* We sent cached result so no need for timeout
1783                                  * handler.
1784                                  */
1785                                 if (req->timeout > 0) {
1786                                         g_source_remove(req->timeout);
1787                                         req->timeout = 0;
1788                                 }
1789                         }
1790                 }
1791
1792         } else if (condition & G_IO_IN) {
1793                 struct partial_reply *reply = server->incoming_reply;
1794                 int bytes_recv;
1795
1796                 if (!reply) {
1797                         unsigned char reply_len_buf[2];
1798                         uint16_t reply_len;
1799
1800                         bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK);
1801                         if (!bytes_recv) {
1802                                 goto hangup;
1803                         } else if (bytes_recv < 0) {
1804                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
1805                                         return TRUE;
1806
1807                                 connman_error("DNS proxy error %s",
1808                                                 strerror(errno));
1809                                 goto hangup;
1810                         } else if (bytes_recv < 2)
1811                                 return TRUE;
1812
1813                         reply_len = reply_len_buf[1] | reply_len_buf[0] << 8;
1814                         reply_len += 2;
1815
1816                         DBG("TCP reply %d bytes", reply_len);
1817
1818                         reply = g_try_malloc(sizeof(*reply) + reply_len + 2);
1819                         if (!reply)
1820                                 return TRUE;
1821
1822                         reply->len = reply_len;
1823                         reply->received = 0;
1824
1825                         server->incoming_reply = reply;
1826                 }
1827
1828                 while (reply->received < reply->len) {
1829                         bytes_recv = recv(sk, reply->buf + reply->received,
1830                                         reply->len - reply->received, 0);
1831                         if (!bytes_recv) {
1832                                 connman_error("DNS proxy TCP disconnect");
1833                                 break;
1834                         } else if (bytes_recv < 0) {
1835                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
1836                                         return TRUE;
1837
1838                                 connman_error("DNS proxy error %s",
1839                                                 strerror(errno));
1840                                 break;
1841                         }
1842                         reply->received += bytes_recv;
1843                 }
1844
1845                 forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP,
1846                                         server);
1847
1848                 g_free(reply);
1849                 server->incoming_reply = NULL;
1850
1851                 destroy_server(server);
1852
1853                 return FALSE;
1854         }
1855
1856         return TRUE;
1857 }
1858
1859 static gboolean tcp_idle_timeout(gpointer user_data)
1860 {
1861         struct server_data *server = user_data;
1862
1863         DBG("");
1864
1865         if (server == NULL)
1866                 return FALSE;
1867
1868         destroy_server(server);
1869
1870         return FALSE;
1871 }
1872
1873 static struct server_data *create_server(const char *interface,
1874                                         const char *domain, const char *server,
1875                                         int protocol)
1876 {
1877         struct addrinfo hints, *rp;
1878         struct server_data *data;
1879         int sk, ret;
1880
1881         DBG("interface %s server %s", interface, server);
1882
1883         memset(&hints, 0, sizeof(hints));
1884
1885         switch (protocol) {
1886         case IPPROTO_UDP:
1887                 hints.ai_socktype = SOCK_DGRAM;
1888                 break;
1889
1890         case IPPROTO_TCP:
1891                 hints.ai_socktype = SOCK_STREAM;
1892                 break;
1893
1894         default:
1895                 return NULL;
1896         }
1897         hints.ai_family = AF_UNSPEC;
1898         hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
1899
1900         ret = getaddrinfo(server, "53", &hints, &rp);
1901         if (ret) {
1902                 connman_error("Failed to parse server %s address: %s\n",
1903                               server, gai_strerror(ret));
1904                 return NULL;
1905         }
1906         /* Do not blindly copy this code elsewhere; it doesn't loop over the
1907            results using ->ai_next as it should. That's OK in *this* case
1908            because it was a numeric lookup; we *know* there's only one. */
1909
1910         sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
1911         if (sk < 0) {
1912                 connman_error("Failed to create server %s socket", server);
1913                 freeaddrinfo(rp);
1914                 return NULL;
1915         }
1916
1917         if (interface != NULL) {
1918                 if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
1919                                 interface, strlen(interface) + 1) < 0) {
1920                         connman_error("Failed to bind server %s "
1921                                                 "to interface %s",
1922                                                         server, interface);
1923                         freeaddrinfo(rp);
1924                         close(sk);
1925                         return NULL;
1926                 }
1927         }
1928
1929         data = g_try_new0(struct server_data, 1);
1930         if (data == NULL) {
1931                 connman_error("Failed to allocate server %s data", server);
1932                 freeaddrinfo(rp);
1933                 close(sk);
1934                 return NULL;
1935         }
1936
1937         data->channel = g_io_channel_unix_new(sk);
1938         if (data->channel == NULL) {
1939                 connman_error("Failed to create server %s channel", server);
1940                 freeaddrinfo(rp);
1941                 close(sk);
1942                 g_free(data);
1943                 return NULL;
1944         }
1945
1946         g_io_channel_set_close_on_unref(data->channel, TRUE);
1947
1948         if (protocol == IPPROTO_TCP) {
1949                 g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL);
1950                 data->watch = g_io_add_watch(data->channel,
1951                         G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR,
1952                                                 tcp_server_event, data);
1953                 data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout,
1954                                                                 data);
1955         } else
1956                 data->watch = g_io_add_watch(data->channel,
1957                         G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
1958                                                 udp_server_event, data);
1959
1960         data->interface = g_strdup(interface);
1961         if (domain)
1962                 data->domains = g_list_append(data->domains, g_strdup(domain));
1963         data->server = g_strdup(server);
1964         data->protocol = protocol;
1965
1966         ret = connect(sk, rp->ai_addr, rp->ai_addrlen);
1967         freeaddrinfo(rp);
1968         if (ret < 0) {
1969                 if ((protocol == IPPROTO_TCP && errno != EINPROGRESS) ||
1970                                 protocol == IPPROTO_UDP) {
1971                         GList *list;
1972
1973                         connman_error("Failed to connect to server %s", server);
1974                         if (data->watch > 0)
1975                                 g_source_remove(data->watch);
1976                         if (data->timeout > 0)
1977                                 g_source_remove(data->timeout);
1978
1979                         g_io_channel_unref(data->channel);
1980                         close(sk);
1981
1982                         g_free(data->server);
1983                         g_free(data->interface);
1984                         for (list = data->domains; list; list = list->next) {
1985                                 char *domain = list->data;
1986
1987                                 data->domains = g_list_remove(data->domains,
1988                                                                         domain);
1989                                 g_free(domain);
1990                         }
1991                         g_free(data);
1992                         return NULL;
1993                 }
1994         }
1995
1996         if (__sync_fetch_and_add(&cache_refcount, 1) == 0)
1997                 cache = g_hash_table_new_full(g_str_hash,
1998                                         g_str_equal,
1999                                         NULL,
2000                                         cache_element_destroy);
2001
2002         if (protocol == IPPROTO_UDP) {
2003                 /* Enable new servers by default */
2004                 data->enabled = TRUE;
2005                 connman_info("Adding DNS server %s", data->server);
2006
2007                 server_list = g_slist_append(server_list, data);
2008
2009                 return data;
2010         }
2011
2012         return NULL;
2013 }
2014
2015 static gboolean resolv(struct request_data *req,
2016                                 gpointer request, gpointer name)
2017 {
2018         GSList *list;
2019         int status;
2020
2021         for (list = server_list; list; list = list->next) {
2022                 struct server_data *data = list->data;
2023
2024                 DBG("server %s enabled %d", data->server, data->enabled);
2025
2026                 if (data->enabled == FALSE)
2027                         continue;
2028
2029                 if (data->watch == 0 && data->protocol == IPPROTO_UDP)
2030                         data->watch = g_io_add_watch(data->channel,
2031                                 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
2032                                                 udp_server_event, data);
2033
2034                 status = ns_resolv(data, req, request, name);
2035                 if (status < 0)
2036                         continue;
2037
2038                 if (status > 0) {
2039                         if (req->timeout > 0) {
2040                                 g_source_remove(req->timeout);
2041                                 req->timeout = 0;
2042                         }
2043                 }
2044         }
2045
2046         return TRUE;
2047 }
2048
2049 static void append_domain(const char *interface, const char *domain)
2050 {
2051         GSList *list;
2052
2053         DBG("interface %s domain %s", interface, domain);
2054
2055         if (domain == NULL)
2056                 return;
2057
2058         for (list = server_list; list; list = list->next) {
2059                 struct server_data *data = list->data;
2060                 GList *dom_list;
2061                 char *dom;
2062                 gboolean dom_found = FALSE;
2063
2064                 if (data->interface == NULL)
2065                         continue;
2066
2067                 if (g_str_equal(data->interface, interface) == FALSE)
2068                         continue;
2069
2070                 for (dom_list = data->domains; dom_list;
2071                                 dom_list = dom_list->next) {
2072                         dom = dom_list->data;
2073
2074                         if (g_str_equal(dom, domain)) {
2075                                 dom_found = TRUE;
2076                                 break;
2077                         }
2078                 }
2079
2080                 if (dom_found == FALSE) {
2081                         data->domains =
2082                                 g_list_append(data->domains, g_strdup(domain));
2083                 }
2084         }
2085 }
2086
2087 int __connman_dnsproxy_append(const char *interface, const char *domain,
2088                                                         const char *server)
2089 {
2090         struct server_data *data;
2091
2092         DBG("interface %s server %s", interface, server);
2093
2094         if (server == NULL && domain == NULL)
2095                 return -EINVAL;
2096
2097         if (server == NULL) {
2098                 append_domain(interface, domain);
2099
2100                 return 0;
2101         }
2102
2103         if (g_str_equal(server, "127.0.0.1") == TRUE)
2104                 return -ENODEV;
2105
2106         data = find_server(interface, server, IPPROTO_UDP);
2107         if (data != NULL) {
2108                 append_domain(interface, domain);
2109                 return 0;
2110         }
2111
2112         data = create_server(interface, domain, server, IPPROTO_UDP);
2113         if (data == NULL)
2114                 return -EIO;
2115
2116         return 0;
2117 }
2118
2119 static void remove_server(const char *interface, const char *domain,
2120                         const char *server, int protocol)
2121 {
2122         struct server_data *data;
2123
2124         data = find_server(interface, server, protocol);
2125         if (data == NULL)
2126                 return;
2127
2128         destroy_server(data);
2129 }
2130
2131 int __connman_dnsproxy_remove(const char *interface, const char *domain,
2132                                                         const char *server)
2133 {
2134         DBG("interface %s server %s", interface, server);
2135
2136         if (server == NULL)
2137                 return -EINVAL;
2138
2139         if (g_str_equal(server, "127.0.0.1") == TRUE)
2140                 return -ENODEV;
2141
2142         remove_server(interface, domain, server, IPPROTO_UDP);
2143         remove_server(interface, domain, server, IPPROTO_TCP);
2144
2145         return 0;
2146 }
2147
2148 void __connman_dnsproxy_flush(void)
2149 {
2150         GSList *list;
2151
2152         list = request_pending_list;
2153         while (list) {
2154                 struct request_data *req = list->data;
2155
2156                 list = list->next;
2157
2158                 request_pending_list =
2159                                 g_slist_remove(request_pending_list, req);
2160                 resolv(req, req->request, req->name);
2161                 g_free(req->request);
2162                 g_free(req->name);
2163         }
2164 }
2165
2166 static void dnsproxy_offline_mode(connman_bool_t enabled)
2167 {
2168         GSList *list;
2169
2170         DBG("enabled %d", enabled);
2171
2172         for (list = server_list; list; list = list->next) {
2173                 struct server_data *data = list->data;
2174
2175                 if (enabled == FALSE) {
2176                         connman_info("Enabling DNS server %s", data->server);
2177                         data->enabled = TRUE;
2178                         cache_invalidate();
2179                         cache_refresh();
2180                 } else {
2181                         connman_info("Disabling DNS server %s", data->server);
2182                         data->enabled = FALSE;
2183                         cache_invalidate();
2184                 }
2185         }
2186 }
2187
2188 static void dnsproxy_default_changed(struct connman_service *service)
2189 {
2190         GSList *list;
2191         char *interface;
2192
2193         DBG("service %p", service);
2194
2195         /* DNS has changed, invalidate the cache */
2196         cache_invalidate();
2197
2198         if (service == NULL) {
2199                 /* When no services are active, then disable DNS proxying */
2200                 dnsproxy_offline_mode(TRUE);
2201                 return;
2202         }
2203
2204         interface = connman_service_get_interface(service);
2205         if (interface == NULL)
2206                 return;
2207
2208         for (list = server_list; list; list = list->next) {
2209                 struct server_data *data = list->data;
2210
2211                 if (g_strcmp0(data->interface, interface) == 0) {
2212                         connman_info("Enabling DNS server %s", data->server);
2213                         data->enabled = TRUE;
2214                 } else {
2215                         connman_info("Disabling DNS server %s", data->server);
2216                         data->enabled = FALSE;
2217                 }
2218         }
2219
2220         g_free(interface);
2221         cache_refresh();
2222 }
2223
2224 static struct connman_notifier dnsproxy_notifier = {
2225         .name                   = "dnsproxy",
2226         .default_changed        = dnsproxy_default_changed,
2227         .offline_mode           = dnsproxy_offline_mode,
2228 };
2229
2230 static unsigned char opt_edns0_type[2] = { 0x00, 0x29 };
2231
2232 static int parse_request(unsigned char *buf, int len,
2233                                         char *name, unsigned int size)
2234 {
2235         struct domain_hdr *hdr = (void *) buf;
2236         uint16_t qdcount = ntohs(hdr->qdcount);
2237         uint16_t arcount = ntohs(hdr->arcount);
2238         unsigned char *ptr;
2239         char *last_label = NULL;
2240         unsigned int remain, used = 0;
2241
2242         if (len < 12)
2243                 return -EINVAL;
2244
2245         DBG("id 0x%04x qr %d opcode %d qdcount %d arcount %d",
2246                                         hdr->id, hdr->qr, hdr->opcode,
2247                                                         qdcount, arcount);
2248
2249         if (hdr->qr != 0 || qdcount != 1)
2250                 return -EINVAL;
2251
2252         memset(name, 0, size);
2253
2254         ptr = buf + sizeof(struct domain_hdr);
2255         remain = len - sizeof(struct domain_hdr);
2256
2257         while (remain > 0) {
2258                 uint8_t len = *ptr;
2259
2260                 if (len == 0x00) {
2261                         last_label = (char *) (ptr + 1);
2262                         break;
2263                 }
2264
2265                 if (used + len + 1 > size)
2266                         return -ENOBUFS;
2267
2268                 strncat(name, (char *) (ptr + 1), len);
2269                 strcat(name, ".");
2270
2271                 used += len + 1;
2272
2273                 ptr += len + 1;
2274                 remain -= len + 1;
2275         }
2276
2277         if (last_label && arcount && remain >= 9 && last_label[4] == 0 &&
2278                                 !memcmp(last_label + 5, opt_edns0_type, 2)) {
2279                 uint16_t edns0_bufsize;
2280
2281                 edns0_bufsize = last_label[7] << 8 | last_label[8];
2282
2283                 DBG("EDNS0 buffer size %u", edns0_bufsize);
2284
2285                 /* This is an evil hack until full TCP support has been
2286                  * implemented.
2287                  *
2288                  * Somtimes the EDNS0 request gets send with a too-small
2289                  * buffer size. Since glibc doesn't seem to crash when it
2290                  * gets a response biffer then it requested, just bump
2291                  * the buffer size up to 4KiB.
2292                  */
2293                 if (edns0_bufsize < 0x1000) {
2294                         last_label[7] = 0x10;
2295                         last_label[8] = 0x00;
2296                 }
2297         }
2298
2299         DBG("query %s", name);
2300
2301         return 0;
2302 }
2303
2304 static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
2305                                                         gpointer user_data)
2306 {
2307         unsigned char buf[768];
2308         char query[512];
2309         struct request_data *req;
2310         struct server_data *server;
2311         int sk, client_sk, len, err;
2312         struct sockaddr_in6 client_addr;
2313         socklen_t client_addr_len = sizeof(client_addr);
2314         GSList *list;
2315         struct listener_data *ifdata = user_data;
2316
2317         DBG("condition 0x%x", condition);
2318
2319         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
2320                 if (ifdata->tcp_listener_watch > 0)
2321                         g_source_remove(ifdata->tcp_listener_watch);
2322                 ifdata->tcp_listener_watch = 0;
2323
2324                 connman_error("Error with TCP listener channel");
2325
2326                 return FALSE;
2327         }
2328
2329         sk = g_io_channel_unix_get_fd(channel);
2330
2331         client_sk = accept(sk, (void *)&client_addr, &client_addr_len);
2332         if (client_sk < 0) {
2333                 connman_error("Accept failure on TCP listener");
2334                 ifdata->tcp_listener_watch = 0;
2335                 return FALSE;
2336         }
2337
2338         len = recv(client_sk, buf, sizeof(buf), 0);
2339         if (len < 2)
2340                 return TRUE;
2341
2342         DBG("Received %d bytes (id 0x%04x)", len, buf[2] | buf[3] << 8);
2343
2344         err = parse_request(buf + 2, len - 2, query, sizeof(query));
2345         if (err < 0 || (g_slist_length(server_list) == 0)) {
2346                 send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP);
2347                 return TRUE;
2348         }
2349
2350         req = g_try_new0(struct request_data, 1);
2351         if (req == NULL)
2352                 return TRUE;
2353
2354         memcpy(&req->sa, &client_addr, client_addr_len);
2355         req->sa_len = client_addr_len;
2356         req->client_sk = client_sk;
2357         req->protocol = IPPROTO_TCP;
2358
2359         request_id += 2;
2360         if (request_id == 0x0000 || request_id == 0xffff)
2361                 request_id += 2;
2362
2363         req->srcid = buf[2] | (buf[3] << 8);
2364         req->dstid = request_id;
2365         req->altid = request_id + 1;
2366         req->request_len = len;
2367
2368         buf[2] = req->dstid & 0xff;
2369         buf[3] = req->dstid >> 8;
2370
2371         req->numserv = 0;
2372         req->ifdata = (struct listener_data *) ifdata;
2373         req->append_domain = FALSE;
2374         request_list = g_slist_append(request_list, req);
2375
2376         for (list = server_list; list; list = list->next) {
2377                 struct server_data *data = list->data;
2378                 GList *domains;
2379
2380                 if (data->protocol != IPPROTO_UDP || data->enabled == FALSE)
2381                         continue;
2382
2383                 server = create_server(data->interface, NULL,
2384                                         data->server, IPPROTO_TCP);
2385
2386                 /*
2387                  * If server is NULL, we're not connected yet.
2388                  * Copy the relevant buffers and continue with
2389                  * the next nameserver.
2390                  * The request will actually be sent once we're
2391                  * properly connected over TCP to this nameserver.
2392                  */
2393                 if (server == NULL) {
2394                         req->request = g_try_malloc0(req->request_len);
2395                         if (req->request == NULL)
2396                                 return TRUE;
2397
2398                         memcpy(req->request, buf, req->request_len);
2399
2400                         req->name = g_try_malloc0(sizeof(query));
2401                         if (req->name == NULL) {
2402                                 g_free(req->request);
2403                                 return TRUE;
2404                         }
2405                         memcpy(req->name, query, sizeof(query));
2406
2407                         continue;
2408                 }
2409
2410                 if (req->timeout > 0)
2411                         g_source_remove(req->timeout);
2412
2413                 for (domains = data->domains; domains;
2414                                 domains = domains->next) {
2415                         char *dom = domains->data;
2416
2417                         DBG("Adding domain %s to %s", dom, server->server);
2418
2419                         server->domains = g_list_append(server->domains,
2420                                                 g_strdup(dom));
2421                 }
2422
2423                 req->timeout = g_timeout_add_seconds(30, request_timeout, req);
2424                 if (ns_resolv(server, req, buf, query) > 0) {
2425                         if (req->timeout > 0) {
2426                                 g_source_remove(req->timeout);
2427                                 req->timeout = 0;
2428                         }
2429                 }
2430         }
2431
2432         return TRUE;
2433 }
2434
2435 static gboolean udp_listener_event(GIOChannel *channel, GIOCondition condition,
2436                                                         gpointer user_data)
2437 {
2438         unsigned char buf[768];
2439         char query[512];
2440         struct request_data *req;
2441         struct sockaddr_in6 client_addr;
2442         socklen_t client_addr_len = sizeof(client_addr);
2443         int sk, err, len;
2444         struct listener_data *ifdata = user_data;
2445
2446         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
2447                 connman_error("Error with UDP listener channel");
2448                 ifdata->udp_listener_watch = 0;
2449                 return FALSE;
2450         }
2451
2452         sk = g_io_channel_unix_get_fd(channel);
2453
2454         memset(&client_addr, 0, client_addr_len);
2455         len = recvfrom(sk, buf, sizeof(buf), 0, (void *)&client_addr,
2456                        &client_addr_len);
2457         if (len < 2)
2458                 return TRUE;
2459
2460         DBG("Received %d bytes (id 0x%04x)", len, buf[0] | buf[1] << 8);
2461
2462         err = parse_request(buf, len, query, sizeof(query));
2463         if (err < 0 || (g_slist_length(server_list) == 0)) {
2464                 send_response(sk, buf, len, (void *)&client_addr,
2465                                 client_addr_len, IPPROTO_UDP);
2466                 return TRUE;
2467         }
2468
2469         req = g_try_new0(struct request_data, 1);
2470         if (req == NULL)
2471                 return TRUE;
2472
2473         memcpy(&req->sa, &client_addr, client_addr_len);
2474         req->sa_len = client_addr_len;
2475         req->client_sk = 0;
2476         req->protocol = IPPROTO_UDP;
2477
2478         request_id += 2;
2479         if (request_id == 0x0000 || request_id == 0xffff)
2480                 request_id += 2;
2481
2482         req->srcid = buf[0] | (buf[1] << 8);
2483         req->dstid = request_id;
2484         req->altid = request_id + 1;
2485         req->request_len = len;
2486
2487         buf[0] = req->dstid & 0xff;
2488         buf[1] = req->dstid >> 8;
2489
2490         req->numserv = 0;
2491         req->ifdata = (struct listener_data *) ifdata;
2492         req->timeout = g_timeout_add_seconds(5, request_timeout, req);
2493         req->append_domain = FALSE;
2494         request_list = g_slist_append(request_list, req);
2495
2496         return resolv(req, buf, query);
2497 }
2498
2499 static int create_dns_listener(int protocol, struct listener_data *ifdata)
2500 {
2501         GIOChannel *channel;
2502         const char *proto;
2503         union {
2504                 struct sockaddr sa;
2505                 struct sockaddr_in6 sin6;
2506                 struct sockaddr_in sin;
2507         } s;
2508         socklen_t slen;
2509         int sk, type, v6only = 0;
2510         int family = AF_INET6;
2511
2512
2513         DBG("interface %s", ifdata->ifname);
2514
2515         switch (protocol) {
2516         case IPPROTO_UDP:
2517                 proto = "UDP";
2518                 type = SOCK_DGRAM | SOCK_CLOEXEC;
2519                 break;
2520
2521         case IPPROTO_TCP:
2522                 proto = "TCP";
2523                 type = SOCK_STREAM | SOCK_CLOEXEC;
2524                 break;
2525
2526         default:
2527                 return -EINVAL;
2528         }
2529
2530         sk = socket(family, type, protocol);
2531         if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
2532                 connman_error("No IPv6 support; DNS proxy listening only on Legacy IP");
2533                 family = AF_INET;
2534                 sk = socket(family, type, protocol);
2535         }
2536         if (sk < 0) {
2537                 connman_error("Failed to create %s listener socket", proto);
2538                 return -EIO;
2539         }
2540
2541         if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
2542                                         ifdata->ifname,
2543                                         strlen(ifdata->ifname) + 1) < 0) {
2544                 connman_error("Failed to bind %s listener interface", proto);
2545                 close(sk);
2546                 return -EIO;
2547         }
2548         /* Ensure it accepts Legacy IP connections too */
2549         if (family == AF_INET6 &&
2550                         setsockopt(sk, SOL_IPV6, IPV6_V6ONLY,
2551                                         &v6only, sizeof(v6only)) < 0) {
2552                 connman_error("Failed to clear V6ONLY on %s listener socket",
2553                               proto);
2554                 close(sk);
2555                 return -EIO;
2556         }
2557
2558         if (family == AF_INET) {
2559                 memset(&s.sin, 0, sizeof(s.sin));
2560                 s.sin.sin_family = AF_INET;
2561                 s.sin.sin_port = htons(53);
2562                 s.sin.sin_addr.s_addr = htonl(INADDR_ANY);
2563                 slen = sizeof(s.sin);
2564         } else {
2565                 memset(&s.sin6, 0, sizeof(s.sin6));
2566                 s.sin6.sin6_family = AF_INET6;
2567                 s.sin6.sin6_port = htons(53);
2568                 s.sin6.sin6_addr = in6addr_any;
2569                 slen = sizeof(s.sin6);
2570         }
2571
2572         if (bind(sk, &s.sa, slen) < 0) {
2573                 connman_error("Failed to bind %s listener socket", proto);
2574                 close(sk);
2575                 return -EIO;
2576         }
2577
2578         if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) {
2579                 connman_error("Failed to listen on TCP socket");
2580                 close(sk);
2581                 return -EIO;
2582         }
2583
2584         channel = g_io_channel_unix_new(sk);
2585         if (channel == NULL) {
2586                 connman_error("Failed to create %s listener channel", proto);
2587                 close(sk);
2588                 return -EIO;
2589         }
2590
2591         g_io_channel_set_close_on_unref(channel, TRUE);
2592
2593         if (protocol == IPPROTO_TCP) {
2594                 ifdata->tcp_listener_channel = channel;
2595                 ifdata->tcp_listener_watch = g_io_add_watch(channel,
2596                                 G_IO_IN, tcp_listener_event, (gpointer) ifdata);
2597         } else {
2598                 ifdata->udp_listener_channel = channel;
2599                 ifdata->udp_listener_watch = g_io_add_watch(channel,
2600                                 G_IO_IN, udp_listener_event, (gpointer) ifdata);
2601         }
2602
2603         return 0;
2604 }
2605
2606 static void destroy_udp_listener(struct listener_data *ifdata)
2607 {
2608         DBG("interface %s", ifdata->ifname);
2609
2610         if (ifdata->udp_listener_watch > 0)
2611                 g_source_remove(ifdata->udp_listener_watch);
2612
2613         g_io_channel_unref(ifdata->udp_listener_channel);
2614 }
2615
2616 static void destroy_tcp_listener(struct listener_data *ifdata)
2617 {
2618         DBG("interface %s", ifdata->ifname);
2619
2620         if (ifdata->tcp_listener_watch > 0)
2621                 g_source_remove(ifdata->tcp_listener_watch);
2622
2623         g_io_channel_unref(ifdata->tcp_listener_channel);
2624 }
2625
2626 static int create_listener(struct listener_data *ifdata)
2627 {
2628         int err;
2629
2630         err = create_dns_listener(IPPROTO_UDP, ifdata);
2631         if (err < 0)
2632                 return err;
2633
2634         err = create_dns_listener(IPPROTO_TCP, ifdata);
2635         if (err < 0) {
2636                 destroy_udp_listener(ifdata);
2637                 return err;
2638         }
2639
2640         if (g_strcmp0(ifdata->ifname, "lo") == 0)
2641                 __connman_resolvfile_append("lo", NULL, "127.0.0.1");
2642
2643         return 0;
2644 }
2645
2646 static void destroy_listener(struct listener_data *ifdata)
2647 {
2648         GSList *list;
2649
2650         if (g_strcmp0(ifdata->ifname, "lo") == 0)
2651                 __connman_resolvfile_remove("lo", NULL, "127.0.0.1");
2652
2653         for (list = request_pending_list; list; list = list->next) {
2654                 struct request_data *req = list->data;
2655
2656                 DBG("Dropping pending request (id 0x%04x -> 0x%04x)",
2657                                                 req->srcid, req->dstid);
2658
2659                 g_free(req->resp);
2660                 g_free(req->request);
2661                 g_free(req->name);
2662                 g_free(req);
2663                 list->data = NULL;
2664         }
2665
2666         g_slist_free(request_pending_list);
2667         request_pending_list = NULL;
2668
2669         for (list = request_list; list; list = list->next) {
2670                 struct request_data *req = list->data;
2671
2672                 DBG("Dropping request (id 0x%04x -> 0x%04x)",
2673                                                 req->srcid, req->dstid);
2674
2675                 g_free(req->resp);
2676                 g_free(req->request);
2677                 g_free(req->name);
2678                 g_free(req);
2679                 list->data = NULL;
2680         }
2681
2682         g_slist_free(request_list);
2683         request_list = NULL;
2684
2685         destroy_tcp_listener(ifdata);
2686         destroy_udp_listener(ifdata);
2687 }
2688
2689 int __connman_dnsproxy_add_listener(const char *interface)
2690 {
2691         struct listener_data *ifdata;
2692         int err;
2693
2694         DBG("interface %s", interface);
2695
2696         if (g_hash_table_lookup(listener_table, interface) != NULL)
2697                 return 0;
2698
2699         ifdata = g_try_new0(struct listener_data, 1);
2700         if (ifdata == NULL)
2701                 return -ENOMEM;
2702
2703         ifdata->ifname = g_strdup(interface);
2704         ifdata->udp_listener_channel = NULL;
2705         ifdata->udp_listener_watch = 0;
2706         ifdata->tcp_listener_channel = NULL;
2707         ifdata->tcp_listener_watch = 0;
2708
2709         err = create_listener(ifdata);
2710         if (err < 0) {
2711                 connman_error("Couldn't create listener for %s err %d",
2712                                 interface, err);
2713                 g_free(ifdata->ifname);
2714                 g_free(ifdata);
2715                 return err;
2716         }
2717         g_hash_table_insert(listener_table, ifdata->ifname, ifdata);
2718         return 0;
2719 }
2720
2721 void __connman_dnsproxy_remove_listener(const char *interface)
2722 {
2723         struct listener_data *ifdata;
2724
2725         DBG("interface %s", interface);
2726
2727         ifdata = g_hash_table_lookup(listener_table, interface);
2728         if (ifdata == NULL)
2729                 return;
2730
2731         destroy_listener(ifdata);
2732
2733         g_hash_table_remove(listener_table, interface);
2734 }
2735
2736 static void remove_listener(gpointer key, gpointer value, gpointer user_data)
2737 {
2738         __connman_dnsproxy_remove_listener(key);
2739 }
2740
2741 int __connman_dnsproxy_init(void)
2742 {
2743         int err;
2744
2745         DBG("");
2746
2747         listener_table = g_hash_table_new_full(g_str_hash, g_str_equal,
2748                                                         g_free, g_free);
2749         err = __connman_dnsproxy_add_listener("lo");
2750         if (err < 0)
2751                 return err;
2752
2753         err = connman_notifier_register(&dnsproxy_notifier);
2754         if (err < 0)
2755                 goto destroy;
2756
2757         return 0;
2758
2759 destroy:
2760         __connman_dnsproxy_remove_listener("lo");
2761         g_hash_table_destroy(listener_table);
2762
2763         return err;
2764 }
2765
2766 void __connman_dnsproxy_cleanup(void)
2767 {
2768         DBG("");
2769
2770         connman_notifier_unregister(&dnsproxy_notifier);
2771
2772         g_hash_table_foreach(listener_table, remove_listener, NULL);
2773
2774         g_hash_table_destroy(listener_table);
2775 }