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
  36 #include <glib.h>
  37
  38 #include "connman.h"
  39
  40 #if __BYTE_ORDER == __LITTLE_ENDIAN
  41 struct domain_hdr {
  42         uint16_t id;
  43         uint8_t rd:1;
  44         uint8_t tc:1;
  45         uint8_t aa:1;
  46         uint8_t opcode:4;
  47         uint8_t qr:1;
  48         uint8_t rcode:4;
  49         uint8_t z:3;
  50         uint8_t ra:1;
  51         uint16_t qdcount;
  52         uint16_t ancount;
  53         uint16_t nscount;
  54         uint16_t arcount;
  55 } __attribute__ ((packed));
  56 #elif __BYTE_ORDER == __BIG_ENDIAN
  57 struct domain_hdr {
  58         uint16_t id;
  59         uint8_t qr:1;
  60         uint8_t opcode:4;
  61         uint8_t aa:1;
  62         uint8_t tc:1;
  63         uint8_t rd:1;
  64         uint8_t ra:1;
  65         uint8_t z:3;
  66         uint8_t rcode:4;
  67         uint16_t qdcount;
  68         uint16_t ancount;
  69         uint16_t nscount;
  70         uint16_t arcount;
  71 } __attribute__ ((packed));
  72 #else
  73 #error "Unknown byte order"
  74 #endif
  75
  76 struct partial_reply {
  77         uint16_t len;
  78         uint16_t received;
  79         unsigned char buf[];
  80 };
  81
  82 struct server_data {
  83         char *interface;
  84         GList *domains;
  85         char *server;
  86         int protocol;
  87         GIOChannel *channel;
  88         guint watch;
  89         guint timeout;
  90         gboolean enabled;
  91         gboolean connected;
  92         struct partial_reply *incoming_reply;
  93 };
  94
  95 struct request_data {
  96         union {
  97                 struct sockaddr_in6 __sin6; /* Only for the length */
  98                 struct sockaddr sa;
  99         };
 100         socklen_t sa_len;
 101         int client_sk;
 102         int protocol;
 103         guint16 srcid;
 104         guint16 dstid;
 105         guint16 altid;
 106         guint timeout;
 107         guint watch;
 108         guint numserv;
 109         guint numresp;
 110         gpointer request;
 111         gsize request_len;
 112         gpointer name;
 113         gpointer resp;
 114         gsize resplen;
 115 };
 116
 117 static GSList *server_list = NULL;
 118 static GSList *request_list = NULL;
 119 static GSList *request_pending_list = NULL;
 120 static guint16 request_id = 0x0000;
 121
 122 static GIOChannel *udp_listener_channel = NULL;
 123 static guint udp_listener_watch = 0;
 124 static GIOChannel *tcp_listener_channel = NULL;
 125 static guint tcp_listener_watch = 0;
 126
 127 static int protocol_offset(int protocol)
 128 {
 129         switch (protocol) {
 130         case IPPROTO_UDP:
 131                 return 0;
 132
 133         case IPPROTO_TCP:
 134                 return 2;
 135
 136         default:
 137                 return -EINVAL;
 138         }
 139
 140 }
 141
 142 static struct request_data *find_request(guint16 id)
 143 {
 144         GSList *list;
 145
 146         for (list = request_list; list; list = list->next) {
 147                 struct request_data *req = list->data;
 148
 149                 if (req->dstid == id || req->altid == id)
 150                         return req;
 151         }
 152
 153         return NULL;
 154 }
 155
 156 static struct server_data *find_server(const char *interface,
 157                                         const char *server,
 158                                                 int protocol)
 159 {
 160         GSList *list;
 161
 162         DBG("interface %s server %s", interface, server);
 163
 164         for (list = server_list; list; list = list->next) {
 165                 struct server_data *data = list->data;
 166
 167                 if (interface == NULL && data->interface == NULL &&
 168                                 g_str_equal(data->server, server) == TRUE &&
 169                                 data->protocol == protocol)
 170                         return data;
 171
 172                 if (interface == NULL ||
 173                                 data->interface == NULL || data->server == NULL)
 174                         continue;
 175
 176                 if (g_str_equal(data->interface, interface) == TRUE &&
 177                                 g_str_equal(data->server, server) == TRUE &&
 178                                 data->protocol == protocol)
 179                         return data;
 180         }
 181
 182         return NULL;
 183 }
 184
 185
 186 static void send_response(int sk, unsigned char *buf, int len,
 187                                 const struct sockaddr *to, socklen_t tolen,
 188                                 int protocol)
 189 {
 190         struct domain_hdr *hdr;
 191         int err, offset = protocol_offset(protocol);
 192
 193         DBG("");
 194
 195         if (offset < 0)
 196                 return;
 197
 198         if (len < 12)
 199                 return;
 200
 201         hdr = (void *) (buf + offset);
 202
 203         DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode);
 204
 205         hdr->qr = 1;
 206         hdr->rcode = 2;
 207
 208         hdr->ancount = 0;
 209         hdr->nscount = 0;
 210         hdr->arcount = 0;
 211
 212         err = sendto(sk, buf, len, 0, to, tolen);
 213 }
 214
 215 static gboolean request_timeout(gpointer user_data)
 216 {
 217         struct request_data *req = user_data;
 218
 219         DBG("id 0x%04x", req->srcid);
 220
 221         if (req == NULL)
 222                 return FALSE;
 223
 224         request_list = g_slist_remove(request_list, req);
 225         req->numserv--;
 226
 227         if (req->resplen > 0 && req->resp != NULL) {
 228                 int sk, err;
 229
 230                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 231
 232                 err = sendto(sk, req->resp, req->resplen, 0,
 233                              &req->sa, req->sa_len);
 234         } else if (req->request && req->numserv == 0) {
 235                 struct domain_hdr *hdr;
 236
 237                 if (req->protocol == IPPROTO_TCP) {
 238                         hdr = (void *) (req->request + 2);
 239                         hdr->id = req->srcid;
 240                         send_response(req->client_sk, req->request,
 241                                         req->request_len, NULL, 0, IPPROTO_TCP);
 242
 243                 } else if (req->protocol == IPPROTO_UDP) {
 244                         int sk;
 245
 246                         hdr = (void *) (req->request);
 247                         hdr->id = req->srcid;
 248                         sk = g_io_channel_unix_get_fd(udp_listener_channel);
 249                         send_response(sk, req->request, req->request_len,
 250                                       &req->sa, req->sa_len, IPPROTO_UDP);
 251                 }
 252         }
 253
 254         g_free(req->resp);
 255         g_free(req);
 256
 257         return FALSE;
 258 }
 259
 260 static int append_query(unsigned char *buf, unsigned int size,
 261                                 const char *query, const char *domain)
 262 {
 263         unsigned char *ptr = buf;
 264         char *offset;
 265
 266         DBG("query %s domain %s", query, domain);
 267
 268         offset = (char *) query;
 269         while (offset != NULL) {
 270                 char *tmp;
 271
 272                 tmp = strchr(offset, '.');
 273                 if (tmp == NULL) {
 274                         if (strlen(offset) == 0)
 275                                 break;
 276                         *ptr = strlen(offset);
 277                         memcpy(ptr + 1, offset, strlen(offset));
 278                         ptr += strlen(offset) + 1;
 279                         break;
 280                 }
 281
 282                 *ptr = tmp - offset;
 283                 memcpy(ptr + 1, offset, tmp - offset);
 284                 ptr += tmp - offset + 1;
 285
 286                 offset = tmp + 1;
 287         }
 288
 289         offset = (char *) domain;
 290         while (offset != NULL) {
 291                 char *tmp;
 292
 293                 tmp = strchr(offset, '.');
 294                 if (tmp == NULL) {
 295                         if (strlen(offset) == 0)
 296                                 break;
 297                         *ptr = strlen(offset);
 298                         memcpy(ptr + 1, offset, strlen(offset));
 299                         ptr += strlen(offset) + 1;
 300                         break;
 301                 }
 302
 303                 *ptr = tmp - offset;
 304                 memcpy(ptr + 1, offset, tmp - offset);
 305                 ptr += tmp - offset + 1;
 306
 307                 offset = tmp + 1;
 308         }
 309
 310         *ptr++ = 0x00;
 311
 312         return ptr - buf;
 313 }
 314
 315 static int ns_resolv(struct server_data *server, struct request_data *req,
 316                                 gpointer request, gpointer name)
 317 {
 318         GList *list;
 319         int sk, err;
 320
 321         sk = g_io_channel_unix_get_fd(server->channel);
 322
 323         err = send(sk, request, req->request_len, 0);
 324
 325         req->numserv++;
 326
 327         for (list = server->domains; list; list = list->next) {
 328                 char *domain;
 329                 unsigned char alt[1024];
 330                 struct domain_hdr *hdr = (void *) &alt;
 331                 int altlen, domlen, offset;
 332
 333                 domain = list->data;
 334
 335                 if (domain == NULL)
 336                         continue;
 337
 338                 offset = protocol_offset(server->protocol);
 339                 if (offset < 0)
 340                         return offset;
 341
 342                 domlen = strlen(domain) + 1;
 343                 if (domlen < 5)
 344                         return -EINVAL;
 345
 346                 alt[offset] = req->altid & 0xff;
 347                 alt[offset + 1] = req->altid >> 8;
 348
 349                 memcpy(alt + offset + 2, request + offset + 2, 10);
 350                 hdr->qdcount = htons(1);
 351
 352                 altlen = append_query(alt + offset + 12, sizeof(alt) - 12,
 353                                         name, domain);
 354                 if (altlen < 0)
 355                         return -EINVAL;
 356
 357                 altlen += 12;
 358
 359                 memcpy(alt + offset + altlen,
 360                         request + offset + altlen - domlen,
 361                                 req->request_len - altlen + domlen);
 362
 363                 if (server->protocol == IPPROTO_TCP) {
 364                         int req_len = req->request_len + domlen - 1;
 365
 366                         alt[0] = (req_len >> 8) & 0xff;
 367                         alt[1] = req_len & 0xff;
 368                 }
 369
 370                 err = send(sk, alt, req->request_len + domlen + 1, 0);
 371
 372                 req->numserv++;
 373         }
 374
 375         return 0;
 376 }
 377
 378 static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol)
 379 {
 380         struct domain_hdr *hdr;
 381         struct request_data *req;
 382         int dns_id, sk, err, offset = protocol_offset(protocol);
 383
 384         if (offset < 0)
 385                 return offset;
 386
 387         hdr = (void *)(reply + offset);
 388         dns_id = reply[offset] | reply[offset + 1] << 8;
 389
 390         DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id);
 391
 392         req = find_request(dns_id);
 393         if (req == NULL)
 394                 return -EINVAL;
 395
 396         DBG("id 0x%04x rcode %d", hdr->id, hdr->rcode);
 397
 398         reply[offset] = req->srcid & 0xff;
 399         reply[offset + 1] = req->srcid >> 8;
 400
 401         req->numresp++;
 402
 403         if (hdr->rcode == 0 || req->resp == NULL) {
 404                 g_free(req->resp);
 405                 req->resplen = 0;
 406
 407                 req->resp = g_try_malloc(reply_len);
 408                 if (req->resp == NULL)
 409                         return -ENOMEM;
 410
 411                 memcpy(req->resp, reply, reply_len);
 412                 req->resplen = reply_len;
 413         }
 414
 415         if (hdr->rcode > 0 && req->numresp < req->numserv)
 416                 return -EINVAL;
 417
 418         if (req->timeout > 0)
 419                 g_source_remove(req->timeout);
 420
 421         request_list = g_slist_remove(request_list, req);
 422
 423         if (protocol == IPPROTO_UDP) {
 424                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 425                 err = sendto(sk, req->resp, req->resplen, 0,
 426                              &req->sa, req->sa_len);
 427         } else {
 428                 sk = req->client_sk;
 429                 err = send(sk, req->resp, req->resplen, 0);
 430                 close(sk);
 431         }
 432
 433         g_free(req->resp);
 434         g_free(req);
 435
 436         return err;
 437 }
 438
 439 static void destroy_server(struct server_data *server)
 440 {
 441         GList *list;
 442
 443         DBG("interface %s server %s", server->interface, server->server);
 444
 445         server_list = g_slist_remove(server_list, server);
 446
 447         if (server->watch > 0)
 448                 g_source_remove(server->watch);
 449
 450         if (server->timeout > 0)
 451                 g_source_remove(server->timeout);
 452
 453         g_io_channel_unref(server->channel);
 454
 455         if (server->protocol == IPPROTO_UDP)
 456                 connman_info("Removing DNS server %s", server->server);
 457
 458         g_free(server->incoming_reply);
 459         g_free(server->server);
 460         for (list = server->domains; list; list = list->next) {
 461                 char *domain = list->data;
 462
 463                 server->domains = g_list_remove(server->domains, domain);
 464                 g_free(domain);
 465         }
 466         g_free(server->interface);
 467         g_free(server);
 468 }
 469
 470 static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition,
 471                                                         gpointer user_data)
 472 {
 473         unsigned char buf[4096];
 474         int sk, err, len;
 475
 476         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 477                 struct server_data *data = user_data;
 478
 479                 connman_error("Error with UDP server %s", data->server);
 480                 data->watch = 0;
 481                 return FALSE;
 482         }
 483
 484         sk = g_io_channel_unix_get_fd(channel);
 485
 486         len = recv(sk, buf, sizeof(buf), 0);
 487         if (len < 12)
 488                 return TRUE;
 489
 490         err = forward_dns_reply(buf, len, IPPROTO_UDP);
 491
 492         return TRUE;
 493 }
 494
 495 static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition,
 496                                                         gpointer user_data)
 497 {
 498         int sk;
 499         struct server_data *server = user_data;
 500
 501         sk = g_io_channel_unix_get_fd(channel);
 502         if (sk == 0)
 503                 return FALSE;
 504
 505         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 506                 GSList *list;
 507 hangup:
 508                 DBG("TCP server channel closed");
 509
 510                 /*
 511                  * Discard any partial response which is buffered; better
 512                  * to get a proper response from a working server.
 513                  */
 514                 g_free(server->incoming_reply);
 515                 server->incoming_reply = NULL;
 516
 517                 for (list = request_list; list; list = list->next) {
 518                         struct request_data *req = list->data;
 519                         struct domain_hdr *hdr;
 520
 521                         if (req->protocol == IPPROTO_UDP)
 522                                 continue;
 523
 524                         if (req->request == NULL)
 525                                 continue;
 526
 527                         /*
 528                          * If we're not waiting for any further response
 529                          * from another name server, then we send an error
 530                          * response to the client.
 531                          */
 532                         if (req->numserv && --(req->numserv))
 533                                 continue;
 534
 535                         hdr = (void *) (req->request + 2);
 536                         hdr->id = req->srcid;
 537                         send_response(req->client_sk, req->request,
 538                                         req->request_len, NULL, 0, IPPROTO_TCP);
 539
 540                         request_list = g_slist_remove(request_list, req);
 541                 }
 542
 543                 destroy_server(server);
 544
 545                 return FALSE;
 546         }
 547
 548         if ((condition & G_IO_OUT) && !server->connected) {
 549                 GSList *list;
 550                 GList *domains;
 551                 struct server_data *udp_server;
 552
 553                 udp_server = find_server(server->interface, server->server,
 554                                                                 IPPROTO_UDP);
 555                 if (udp_server != NULL) {
 556                         for (domains = udp_server->domains; domains;
 557                                                 domains = domains->next) {
 558                                 char *dom = domains->data;
 559
 560                                 DBG("Adding domain %s to %s",
 561                                                 dom, server->server);
 562
 563                                 server->domains = g_list_append(server->domains,
 564                                                                 g_strdup(dom));
 565                         }
 566                 }
 567
 568                 server->connected = TRUE;
 569                 server_list = g_slist_append(server_list, server);
 570
 571                 if (server->timeout > 0) {
 572                         g_source_remove(server->timeout);
 573                         server->timeout = 0;
 574                 }
 575
 576                 for (list = request_list; list; list = list->next) {
 577                         struct request_data *req = list->data;
 578
 579                         if (req->protocol == IPPROTO_UDP)
 580                                 continue;
 581
 582                         DBG("Sending req %s over TCP", (char *)req->name);
 583
 584                         if (req->timeout > 0)
 585                                 g_source_remove(req->timeout);
 586
 587                         req->timeout = g_timeout_add_seconds(30,
 588                                                 request_timeout, req);
 589                         ns_resolv(server, req, req->request, req->name);
 590                 }
 591
 592         } else if (condition & G_IO_IN) {
 593                 struct partial_reply *reply = server->incoming_reply;
 594                 int bytes_recv;
 595
 596                 if (!reply) {
 597                         unsigned char reply_len_buf[2];
 598                         uint16_t reply_len;
 599
 600                         bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK);
 601                         if (!bytes_recv) {
 602                                 goto hangup;
 603                         } else if (bytes_recv < 0) {
 604                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 605                                         return TRUE;
 606
 607                                 connman_error("DNS proxy error %s",
 608                                                 strerror(errno));
 609                                 goto hangup;
 610                         } else if (bytes_recv < 2)
 611                                 return TRUE;
 612
 613                         reply_len = reply_len_buf[1] | reply_len_buf[0] << 8;
 614                         reply_len += 2;
 615
 616                         DBG("TCP reply %d bytes", reply_len);
 617
 618                         reply = g_try_malloc(sizeof(*reply) + reply_len + 2);
 619                         if (!reply)
 620                                 return TRUE;
 621
 622                         reply->len = reply_len;
 623                         reply->received = 0;
 624
 625                         server->incoming_reply = reply;
 626                 }
 627
 628                 while (reply->received < reply->len) {
 629                         bytes_recv = recv(sk, reply->buf + reply->received,
 630                                         reply->len - reply->received, 0);
 631                         if (!bytes_recv) {
 632                                 connman_error("DNS proxy TCP disconnect");
 633                                 break;
 634                         } else if (bytes_recv < 0) {
 635                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 636                                         return TRUE;
 637
 638                                 connman_error("DNS proxy error %s",
 639                                                 strerror(errno));
 640                                 break;
 641                         }
 642                         reply->received += bytes_recv;
 643                 }
 644
 645                 forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP);
 646
 647                 g_free(reply);
 648                 server->incoming_reply = NULL;
 649
 650                 destroy_server(server);
 651
 652                 return FALSE;
 653         }
 654
 655         return TRUE;
 656 }
 657
 658 static gboolean tcp_idle_timeout(gpointer user_data)
 659 {
 660         struct server_data *server = user_data;
 661
 662         DBG("");
 663
 664         if (server == NULL)
 665                 return FALSE;
 666
 667         destroy_server(server);
 668
 669         return FALSE;
 670 }
 671
 672 static struct server_data *create_server(const char *interface,
 673                                         const char *domain, const char *server,
 674                                         int protocol)
 675 {
 676         struct addrinfo hints, *rp;
 677         struct server_data *data;
 678         int sk, ret;
 679
 680         DBG("interface %s server %s", interface, server);
 681
 682         memset(&hints, 0, sizeof(hints));
 683
 684         switch (protocol) {
 685         case IPPROTO_UDP:
 686                 hints.ai_socktype = SOCK_DGRAM;
 687                 break;
 688
 689         case IPPROTO_TCP:
 690                 hints.ai_socktype = SOCK_STREAM;
 691                 break;
 692
 693         default:
 694                 return NULL;
 695         }
 696         hints.ai_family = AF_UNSPEC;
 697         hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
 698
 699         ret = getaddrinfo(server, "53", &hints, &rp);
 700         if (ret) {
 701                 connman_error("Failed to parse server %s address: %s\n",
 702                               server, gai_strerror(ret));
 703                 return NULL;
 704         }
 705         /* Do not blindly copy this code elsewhere; it doesn't loop over the
 706            results using ->ai_next as it should. That's OK in *this* case
 707            because it was a numeric lookup; we *know* there's only one. */
 708
 709         sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 710         if (sk < 0) {
 711                 connman_error("Failed to create server %s socket", server);
 712                 freeaddrinfo(rp);
 713                 return NULL;
 714         }
 715
 716         if (interface != NULL) {
 717                 if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
 718                                 interface, strlen(interface) + 1) < 0) {
 719                         connman_error("Failed to bind server %s "
 720                                                 "to interface %s",
 721                                                         server, interface);
 722                         freeaddrinfo(rp);
 723                         close(sk);
 724                         return NULL;
 725                 }
 726         }
 727
 728         data = g_try_new0(struct server_data, 1);
 729         if (data == NULL) {
 730                 connman_error("Failed to allocate server %s data", server);
 731                 freeaddrinfo(rp);
 732                 close(sk);
 733                 return NULL;
 734         }
 735
 736         data->channel = g_io_channel_unix_new(sk);
 737         if (data->channel == NULL) {
 738                 connman_error("Failed to create server %s channel", server);
 739                 freeaddrinfo(rp);
 740                 close(sk);
 741                 g_free(data);
 742                 return NULL;
 743         }
 744
 745         g_io_channel_set_close_on_unref(data->channel, TRUE);
 746
 747         if (protocol == IPPROTO_TCP) {
 748                 g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL);
 749                 data->watch = g_io_add_watch(data->channel,
 750                         G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR,
 751                                                 tcp_server_event, data);
 752                 data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout,
 753                                                                 data);
 754         } else
 755                 data->watch = g_io_add_watch(data->channel,
 756                         G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 757                                                 udp_server_event, data);
 758
 759         data->interface = g_strdup(interface);
 760         if (domain)
 761                 data->domains = g_list_append(data->domains, g_strdup(domain));
 762         data->server = g_strdup(server);
 763         data->protocol = protocol;
 764
 765         ret = connect(sk, rp->ai_addr, rp->ai_addrlen);
 766         freeaddrinfo(rp);
 767         if (ret < 0) {
 768                 if ((protocol == IPPROTO_TCP && errno != EINPROGRESS) ||
 769                                 protocol == IPPROTO_UDP) {
 770                         GList *list;
 771
 772                         connman_error("Failed to connect to server %s", server);
 773                         if (data->watch > 0)
 774                                 g_source_remove(data->watch);
 775                         if (data->timeout > 0)
 776                                 g_source_remove(data->timeout);
 777
 778                         g_io_channel_unref(data->channel);
 779                         close(sk);
 780
 781                         g_free(data->server);
 782                         g_free(data->interface);
 783                         for (list = data->domains; list; list = list->next) {
 784                                 char *domain = list->data;
 785
 786                                 data->domains = g_list_remove(data->domains,
 787                                                                         domain);
 788                                 g_free(domain);
 789                         }
 790                         g_free(data);
 791                         return NULL;
 792                 }
 793         }
 794
 795         if (protocol == IPPROTO_UDP) {
 796                 /* Enable new servers by default */
 797                 data->enabled = TRUE;
 798                 connman_info("Adding DNS server %s", data->server);
 799
 800                 server_list = g_slist_append(server_list, data);
 801
 802                 return data;
 803         }
 804
 805         return NULL;
 806 }
 807
 808 static gboolean resolv(struct request_data *req,
 809                                 gpointer request, gpointer name)
 810 {
 811         GSList *list;
 812
 813         for (list = server_list; list; list = list->next) {
 814                 struct server_data *data = list->data;
 815
 816                 DBG("server %s enabled %d", data->server, data->enabled);
 817
 818                 if (data->enabled == FALSE)
 819                         continue;
 820
 821                 if (data->watch == 0 && data->protocol == IPPROTO_UDP)
 822                         data->watch = g_io_add_watch(data->channel,
 823                                 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 824                                                 udp_server_event, data);
 825
 826                 if (ns_resolv(data, req, request, name) < 0)
 827                         continue;
 828         }
 829
 830         return TRUE;
 831 }
 832
 833 static void append_domain(const char *interface, const char *domain)
 834 {
 835         GSList *list;
 836
 837         DBG("interface %s domain %s", interface, domain);
 838
 839         if (domain == NULL)
 840                 return;
 841
 842         for (list = server_list; list; list = list->next) {
 843                 struct server_data *data = list->data;
 844                 GList *dom_list;
 845                 char *dom;
 846                 gboolean dom_found = FALSE;
 847
 848                 if (data->interface == NULL)
 849                         continue;
 850
 851                 if (g_str_equal(data->interface, interface) == FALSE)
 852                         continue;
 853
 854                 for (dom_list = data->domains; dom_list;
 855                                 dom_list = dom_list->next) {
 856                         dom = dom_list->data;
 857
 858                         if (g_str_equal(dom, domain)) {
 859                                 dom_found = TRUE;
 860                                 break;
 861                         }
 862                 }
 863
 864                 if (dom_found == FALSE) {
 865                         data->domains =
 866                                 g_list_append(data->domains, g_strdup(domain));
 867                 }
 868         }
 869 }
 870
 871 int __connman_dnsproxy_append(const char *interface, const char *domain,
 872                                                         const char *server)
 873 {
 874         struct server_data *data;
 875
 876         DBG("interface %s server %s", interface, server);
 877
 878         if (server == NULL && domain == NULL)
 879                 return -EINVAL;
 880
 881         if (server == NULL) {
 882                 append_domain(interface, domain);
 883
 884                 return 0;
 885         }
 886
 887         if (g_str_equal(server, "127.0.0.1") == TRUE)
 888                 return -ENODEV;
 889
 890         data = find_server(interface, server, IPPROTO_UDP);
 891         if (data != NULL) {
 892                 append_domain(interface, domain);
 893                 return 0;
 894         }
 895
 896         data = create_server(interface, domain, server, IPPROTO_UDP);
 897         if (data == NULL)
 898                 return -EIO;
 899
 900         return 0;
 901 }
 902
 903 static void remove_server(const char *interface, const char *domain,
 904                         const char *server, int protocol)
 905 {
 906         struct server_data *data;
 907
 908         data = find_server(interface, server, protocol);
 909         if (data == NULL)
 910                 return;
 911
 912         destroy_server(data);
 913 }
 914
 915 int __connman_dnsproxy_remove(const char *interface, const char *domain,
 916                                                         const char *server)
 917 {
 918         DBG("interface %s server %s", interface, server);
 919
 920         if (server == NULL)
 921                 return -EINVAL;
 922
 923         if (g_str_equal(server, "127.0.0.1") == TRUE)
 924                 return -ENODEV;
 925
 926         remove_server(interface, domain, server, IPPROTO_UDP);
 927         remove_server(interface, domain, server, IPPROTO_TCP);
 928
 929         return 0;
 930 }
 931
 932 void __connman_dnsproxy_flush(void)
 933 {
 934         GSList *list;
 935
 936         list = request_pending_list;
 937         while (list) {
 938                 struct request_data *req = list->data;
 939
 940                 list = list->next;
 941
 942                 request_pending_list =
 943                                 g_slist_remove(request_pending_list, req);
 944                 resolv(req, req->request, req->name);
 945                 g_free(req->request);
 946                 g_free(req->name);
 947         }
 948 }
 949
 950 static void dnsproxy_offline_mode(connman_bool_t enabled)
 951 {
 952         GSList *list;
 953
 954         DBG("enabled %d", enabled);
 955
 956         for (list = server_list; list; list = list->next) {
 957                 struct server_data *data = list->data;
 958
 959                 if (enabled == FALSE) {
 960                         connman_info("Enabling DNS server %s", data->server);
 961                         data->enabled = TRUE;
 962                 } else {
 963                         connman_info("Disabling DNS server %s", data->server);
 964                         data->enabled = FALSE;
 965                 }
 966         }
 967 }
 968
 969 static void dnsproxy_default_changed(struct connman_service *service)
 970 {
 971         GSList *list;
 972         char *interface;
 973
 974         DBG("service %p", service);
 975
 976         if (service == NULL) {
 977                 /* When no services are active, then disable DNS proxying */
 978                 dnsproxy_offline_mode(TRUE);
 979                 return;
 980         }
 981
 982         interface = connman_service_get_interface(service);
 983         if (interface == NULL)
 984                 return;
 985
 986         for (list = server_list; list; list = list->next) {
 987                 struct server_data *data = list->data;
 988
 989                 if (g_strcmp0(data->interface, interface) == 0) {
 990                         connman_info("Enabling DNS server %s", data->server);
 991                         data->enabled = TRUE;
 992                 } else {
 993                         connman_info("Disabling DNS server %s", data->server);
 994                         data->enabled = FALSE;
 995                 }
 996         }
 997
 998         g_free(interface);
 999 }
1000
1001 static struct connman_notifier dnsproxy_notifier = {
1002         .name                   = "dnsproxy",
1003         .default_changed        = dnsproxy_default_changed,
1004         .offline_mode           = dnsproxy_offline_mode,
1005 };
1006
1007 static unsigned char opt_edns0_type[2] = { 0x00, 0x29 };
1008
1009 static int parse_request(unsigned char *buf, int len,
1010                                         char *name, unsigned int size)
1011 {
1012         struct domain_hdr *hdr = (void *) buf;
1013         uint16_t qdcount = ntohs(hdr->qdcount);
1014         uint16_t arcount = ntohs(hdr->arcount);
1015         unsigned char *ptr;
1016         char *last_label = NULL;
1017         unsigned int remain, used = 0;
1018
1019         if (len < 12)
1020                 return -EINVAL;
1021
1022         DBG("id 0x%04x qr %d opcode %d qdcount %d arcount %d",
1023                                         hdr->id, hdr->qr, hdr->opcode,
1024                                                         qdcount, arcount);
1025
1026         if (hdr->qr != 0 || qdcount != 1)
1027                 return -EINVAL;
1028
1029         memset(name, 0, size);
1030
1031         ptr = buf + sizeof(struct domain_hdr);
1032         remain = len - sizeof(struct domain_hdr);
1033
1034         while (remain > 0) {
1035                 uint8_t len = *ptr;
1036
1037                 if (len == 0x00) {
1038                         last_label = (char *) (ptr + 1);
1039                         break;
1040                 }
1041
1042                 if (used + len + 1 > size)
1043                         return -ENOBUFS;
1044
1045                 strncat(name, (char *) (ptr + 1), len);
1046                 strcat(name, ".");
1047
1048                 used += len + 1;
1049
1050                 ptr += len + 1;
1051                 remain -= len + 1;
1052         }
1053
1054         if (last_label && arcount && remain >= 9 && last_label[4] == 0 &&
1055                                 !memcmp(last_label + 5, opt_edns0_type, 2)) {
1056                 uint16_t edns0_bufsize;
1057
1058                 edns0_bufsize = last_label[7] << 8 | last_label[8];
1059
1060                 DBG("EDNS0 buffer size %u", edns0_bufsize);
1061
1062                 /* This is an evil hack until full TCP support has been
1063                  * implemented.
1064                  *
1065                  * Somtimes the EDNS0 request gets send with a too-small
1066                  * buffer size. Since glibc doesn't seem to crash when it
1067                  * gets a response biffer then it requested, just bump
1068                  * the buffer size up to 4KiB.
1069                  */
1070                 if (edns0_bufsize < 0x1000) {
1071                         last_label[7] = 0x10;
1072                         last_label[8] = 0x00;
1073                 }
1074         }
1075
1076         DBG("query %s", name);
1077
1078         return 0;
1079 }
1080
1081 static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
1082                                                         gpointer user_data)
1083 {
1084         unsigned char buf[768];
1085         char query[512];
1086         struct request_data *req;
1087         struct server_data *server;
1088         int sk, client_sk, len, err;
1089         struct sockaddr_in6 client_addr;
1090         socklen_t client_addr_len = sizeof(client_addr);
1091         GSList *list;
1092
1093         DBG("condition 0x%x", condition);
1094
1095         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1096                 if (tcp_listener_watch > 0)
1097                         g_source_remove(tcp_listener_watch);
1098                 tcp_listener_watch = 0;
1099
1100                 connman_error("Error with TCP listener channel");
1101
1102                 return FALSE;
1103         }
1104
1105         sk = g_io_channel_unix_get_fd(channel);
1106
1107         client_sk = accept(sk, (void *)&client_addr, &client_addr_len);
1108         if (client_sk < 0) {
1109                 connman_error("Accept failure on TCP listener");
1110                 tcp_listener_watch = 0;
1111                 return FALSE;
1112         }
1113
1114         len = recv(client_sk, buf, sizeof(buf), 0);
1115         if (len < 2)
1116                 return TRUE;
1117
1118         DBG("Received %d bytes (id 0x%04x)", len, buf[2] | buf[3] << 8);
1119
1120         err = parse_request(buf + 2, len - 2, query, sizeof(query));
1121         if (err < 0 || (g_slist_length(server_list) == 0)) {
1122                 send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP);
1123                 return TRUE;
1124         }
1125
1126         req = g_try_new0(struct request_data, 1);
1127         if (req == NULL)
1128                 return TRUE;
1129
1130         memcpy(&req->sa, &client_addr, client_addr_len);
1131         req->sa_len = client_addr_len;
1132         req->client_sk = client_sk;
1133         req->protocol = IPPROTO_TCP;
1134
1135         request_id += 2;
1136         if (request_id == 0x0000 || request_id == 0xffff)
1137                 request_id += 2;
1138
1139         req->srcid = buf[2] | (buf[3] << 8);
1140         req->dstid = request_id;
1141         req->altid = request_id + 1;
1142         req->request_len = len;
1143
1144         buf[2] = req->dstid & 0xff;
1145         buf[3] = req->dstid >> 8;
1146
1147         req->numserv = 0;
1148         request_list = g_slist_append(request_list, req);
1149
1150         for (list = server_list; list; list = list->next) {
1151                 struct server_data *data = list->data;
1152                 GList *domains;
1153
1154                 if (data->protocol != IPPROTO_UDP || data->enabled == FALSE)
1155                         continue;
1156
1157                 server = create_server(data->interface, NULL,
1158                                         data->server, IPPROTO_TCP);
1159
1160                 /*
1161                  * If server is NULL, we're not connected yet.
1162                  * Copy the relevant buffers and continue with
1163                  * the next nameserver.
1164                  * The request will actually be sent once we're
1165                  * properly connected over TCP to this nameserver.
1166                  */
1167                 if (server == NULL) {
1168                         req->request = g_try_malloc0(req->request_len);
1169                         if (req->request == NULL)
1170                                 return TRUE;
1171
1172                         memcpy(req->request, buf, req->request_len);
1173
1174                         req->name = g_try_malloc0(sizeof(query));
1175                         if (req->name == NULL) {
1176                                 g_free(req->request);
1177                                 return TRUE;
1178                         }
1179                         memcpy(req->name, query, sizeof(query));
1180
1181                         continue;
1182                 }
1183
1184                 if (req->timeout > 0)
1185                         g_source_remove(req->timeout);
1186
1187                 for (domains = data->domains; domains;
1188                                 domains = domains->next) {
1189                         char *dom = domains->data;
1190
1191                         DBG("Adding domain %s to %s", dom, server->server);
1192
1193                         server->domains = g_list_append(server->domains,
1194                                                 g_strdup(dom));
1195                 }
1196
1197                 req->timeout = g_timeout_add_seconds(30, request_timeout, req);
1198                 ns_resolv(server, req, buf, query);
1199         }
1200
1201         return TRUE;
1202 }
1203
1204 static gboolean udp_listener_event(GIOChannel *channel, GIOCondition condition,
1205                                                         gpointer user_data)
1206 {
1207         unsigned char buf[768];
1208         char query[512];
1209         struct request_data *req;
1210         struct sockaddr_in6 client_addr;
1211         socklen_t client_addr_len = sizeof(client_addr);
1212         int sk, err, len;
1213
1214         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1215                 connman_error("Error with UDP listener channel");
1216                 udp_listener_watch = 0;
1217                 return FALSE;
1218         }
1219
1220         sk = g_io_channel_unix_get_fd(channel);
1221
1222         memset(&client_addr, 0, client_addr_len);
1223         len = recvfrom(sk, buf, sizeof(buf), 0, (void *)&client_addr,
1224                        &client_addr_len);
1225         if (len < 2)
1226                 return TRUE;
1227
1228         DBG("Received %d bytes (id 0x%04x)", len, buf[0] | buf[1] << 8);
1229
1230         err = parse_request(buf, len, query, sizeof(query));
1231         if (err < 0 || (g_slist_length(server_list) == 0)) {
1232                 send_response(sk, buf, len, (void *)&client_addr,
1233                               client_addr_len, IPPROTO_UDP);
1234                 return TRUE;
1235         }
1236
1237         req = g_try_new0(struct request_data, 1);
1238         if (req == NULL)
1239                 return TRUE;
1240
1241         memcpy(&req->sa, &client_addr, client_addr_len);
1242         req->sa_len = client_addr_len;
1243         req->client_sk = 0;
1244         req->protocol = IPPROTO_UDP;
1245
1246         request_id += 2;
1247         if (request_id == 0x0000 || request_id == 0xffff)
1248                 request_id += 2;
1249
1250         req->srcid = buf[0] | (buf[1] << 8);
1251         req->dstid = request_id;
1252         req->altid = request_id + 1;
1253         req->request_len = len;
1254
1255         buf[0] = req->dstid & 0xff;
1256         buf[1] = req->dstid >> 8;
1257
1258         req->numserv = 0;
1259         req->timeout = g_timeout_add_seconds(5, request_timeout, req);
1260         request_list = g_slist_append(request_list, req);
1261
1262         return resolv(req, buf, query);
1263 }
1264
1265 static int create_dns_listener(int protocol)
1266 {
1267         GIOChannel *channel;
1268         const char *ifname = "lo", *proto;
1269         union {
1270                 struct sockaddr sa;
1271                 struct sockaddr_in6 sin6;
1272                 struct sockaddr_in sin;
1273         } s;
1274         socklen_t slen;
1275         int sk, type, v6only = 0;
1276         int family = AF_INET6;
1277
1278         DBG("");
1279
1280         switch (protocol) {
1281         case IPPROTO_UDP:
1282                 proto = "UDP";
1283                 type = SOCK_DGRAM;
1284                 break;
1285
1286         case IPPROTO_TCP:
1287                 proto = "TCP";
1288                 type = SOCK_STREAM;
1289                 break;
1290
1291         default:
1292                 return -EINVAL;
1293         }
1294
1295         sk = socket(family, type, protocol);
1296         if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
1297                 connman_error("No IPv6 support; DNS proxy listening only on Legacy IP");
1298                 family = AF_INET;
1299                 sk = socket(family, type, protocol);
1300         }
1301         if (sk < 0) {
1302                 connman_error("Failed to create %s listener socket", proto);
1303                 return -EIO;
1304         }
1305
1306         if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
1307                                         ifname, strlen(ifname) + 1) < 0) {
1308                 connman_error("Failed to bind %s listener interface", proto);
1309                 close(sk);
1310                 return -EIO;
1311         }
1312         /* Ensure it accepts Legacy IP connections too */
1313         if (family == AF_INET6 &&
1314                         setsockopt(sk, SOL_IPV6, IPV6_V6ONLY,
1315                                         &v6only, sizeof(v6only)) < 0) {
1316                 connman_error("Failed to clear V6ONLY on %s listener socket",
1317                               proto);
1318                 close(sk);
1319                 return -EIO;
1320         }
1321
1322         if (family == AF_INET) {
1323                 memset(&s.sin, 0, sizeof(s.sin));
1324                 s.sin.sin_family = AF_INET;
1325                 s.sin.sin_port = htons(53);
1326                 s.sin.sin_addr.s_addr = htonl(INADDR_ANY);
1327                 slen = sizeof(s.sin);
1328         } else {
1329                 memset(&s.sin6, 0, sizeof(s.sin6));
1330                 s.sin6.sin6_family = AF_INET6;
1331                 s.sin6.sin6_port = htons(53);
1332                 s.sin6.sin6_addr = in6addr_any;
1333                 slen = sizeof(s.sin6);
1334         }
1335
1336         if (bind(sk, &s.sa, slen) < 0) {
1337                 connman_error("Failed to bind %s listener socket", proto);
1338                 close(sk);
1339                 return -EIO;
1340         }
1341
1342         if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) {
1343                 connman_error("Failed to listen on TCP socket");
1344                 close(sk);
1345                 return -EIO;
1346         }
1347
1348         channel = g_io_channel_unix_new(sk);
1349         if (channel == NULL) {
1350                 connman_error("Failed to create %s listener channel", proto);
1351                 close(sk);
1352                 return -EIO;
1353         }
1354
1355         g_io_channel_set_close_on_unref(channel, TRUE);
1356
1357         if (protocol == IPPROTO_TCP) {
1358                 tcp_listener_channel = channel;
1359                 tcp_listener_watch = g_io_add_watch(channel,
1360                                         G_IO_IN, tcp_listener_event, NULL);
1361         } else {
1362                 udp_listener_channel = channel;
1363                 udp_listener_watch = g_io_add_watch(channel,
1364                                         G_IO_IN, udp_listener_event, NULL);
1365         }
1366
1367         return 0;
1368 }
1369
1370 static void destroy_udp_listener(void)
1371 {
1372         DBG("");
1373
1374         if (udp_listener_watch > 0)
1375                 g_source_remove(udp_listener_watch);
1376
1377         g_io_channel_unref(udp_listener_channel);
1378 }
1379
1380 static void destroy_tcp_listener(void)
1381 {
1382         DBG("");
1383
1384         if (tcp_listener_watch > 0)
1385                 g_source_remove(tcp_listener_watch);
1386
1387         g_io_channel_unref(tcp_listener_channel);
1388 }
1389
1390 static int create_listener(void)
1391 {
1392         int err;
1393
1394         err = create_dns_listener(IPPROTO_UDP);
1395         if (err < 0)
1396                 return err;
1397
1398         err = create_dns_listener(IPPROTO_TCP);
1399         if (err < 0) {
1400                 destroy_udp_listener();
1401                 return err;
1402         }
1403
1404         __connman_resolvfile_append("lo", NULL, "127.0.0.1");
1405
1406         return 0;
1407 }
1408
1409 static void destroy_listener(void)
1410 {
1411         GSList *list;
1412
1413         __connman_resolvfile_remove("lo", NULL, "127.0.0.1");
1414
1415         for (list = request_pending_list; list; list = list->next) {
1416                 struct request_data *req = list->data;
1417
1418                 DBG("Dropping pending request (id 0x%04x -> 0x%04x)",
1419                                                 req->srcid, req->dstid);
1420
1421                 g_free(req->resp);
1422                 g_free(req->request);
1423                 g_free(req->name);
1424                 g_free(req);
1425                 list->data = NULL;
1426         }
1427
1428         g_slist_free(request_pending_list);
1429         request_pending_list = NULL;
1430
1431         for (list = request_list; list; list = list->next) {
1432                 struct request_data *req = list->data;
1433
1434                 DBG("Dropping request (id 0x%04x -> 0x%04x)",
1435                                                 req->srcid, req->dstid);
1436
1437                 g_free(req->resp);
1438                 g_free(req->request);
1439                 g_free(req->name);
1440                 g_free(req);
1441                 list->data = NULL;
1442         }
1443
1444         g_slist_free(request_list);
1445         request_list = NULL;
1446
1447         destroy_tcp_listener();
1448         destroy_udp_listener();
1449 }
1450
1451 int __connman_dnsproxy_init(void)
1452 {
1453         int err;
1454
1455         DBG("");
1456
1457         err = create_listener();
1458         if (err < 0)
1459                 return err;
1460
1461         err = connman_notifier_register(&dnsproxy_notifier);
1462         if (err < 0)
1463                 goto destroy;
1464
1465         return 0;
1466
1467 destroy:
1468         destroy_listener();
1469
1470         return err;
1471 }
1472
1473 void __connman_dnsproxy_cleanup(void)
1474 {
1475         DBG("");
1476
1477         connman_notifier_unregister(&dnsproxy_notifier);
1478
1479         destroy_listener();
1480 }