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