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 (interface == NULL && data->interface == NULL &&
 169                                 g_str_equal(data->server, server) == TRUE &&
 170                                 data->protocol == protocol)
 171                         return data;
 172
 173                 if (interface == NULL ||
 174                                 data->interface == NULL || data->server == NULL)
 175                         continue;
 176
 177                 if (g_str_equal(data->interface, interface) == TRUE &&
 178                                 g_str_equal(data->server, server) == TRUE &&
 179                                 data->protocol == protocol)
 180                         return data;
 181         }
 182
 183         return NULL;
 184 }
 185
 186
 187 static void send_response(int sk, unsigned char *buf, int len,
 188                                 const struct sockaddr *to, socklen_t tolen,
 189                                 int protocol)
 190 {
 191         struct domain_hdr *hdr;
 192         int err, offset = protocol_offset(protocol);
 193
 194         DBG("");
 195
 196         if (offset < 0)
 197                 return;
 198
 199         if (len < 12)
 200                 return;
 201
 202         hdr = (void *) (buf + offset);
 203
 204         DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode);
 205
 206         hdr->qr = 1;
 207         hdr->rcode = 2;
 208
 209         hdr->ancount = 0;
 210         hdr->nscount = 0;
 211         hdr->arcount = 0;
 212
 213         err = sendto(sk, buf, len, 0, to, tolen);
 214 }
 215
 216 static gboolean request_timeout(gpointer user_data)
 217 {
 218         struct request_data *req = user_data;
 219
 220         DBG("id 0x%04x", req->srcid);
 221
 222         if (req == NULL)
 223                 return FALSE;
 224
 225         request_list = g_slist_remove(request_list, req);
 226         req->numserv--;
 227
 228         if (req->resplen > 0 && req->resp != NULL) {
 229                 int sk, err;
 230
 231                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 232
 233                 err = sendto(sk, req->resp, req->resplen, 0,
 234                              &req->sa, req->sa_len);
 235         } else if (req->request && req->numserv == 0) {
 236                 struct domain_hdr *hdr;
 237
 238                 if (req->protocol == IPPROTO_TCP) {
 239                         hdr = (void *) (req->request + 2);
 240                         hdr->id = req->srcid;
 241                         send_response(req->client_sk, req->request,
 242                                         req->request_len, NULL, 0, IPPROTO_TCP);
 243
 244                 } else if (req->protocol == IPPROTO_UDP) {
 245                         int sk;
 246
 247                         hdr = (void *) (req->request);
 248                         hdr->id = req->srcid;
 249                         sk = g_io_channel_unix_get_fd(udp_listener_channel);
 250                         send_response(sk, req->request, req->request_len,
 251                                       &req->sa, req->sa_len, IPPROTO_UDP);
 252                 }
 253         }
 254
 255         g_free(req->resp);
 256         g_free(req);
 257
 258         return FALSE;
 259 }
 260
 261 static int append_query(unsigned char *buf, unsigned int size,
 262                                 const char *query, const char *domain)
 263 {
 264         unsigned char *ptr = buf;
 265         char *offset;
 266
 267         DBG("query %s domain %s", query, domain);
 268
 269         offset = (char *) query;
 270         while (offset != NULL) {
 271                 char *tmp;
 272
 273                 tmp = strchr(offset, '.');
 274                 if (tmp == NULL) {
 275                         if (strlen(offset) == 0)
 276                                 break;
 277                         *ptr = strlen(offset);
 278                         memcpy(ptr + 1, offset, strlen(offset));
 279                         ptr += strlen(offset) + 1;
 280                         break;
 281                 }
 282
 283                 *ptr = tmp - offset;
 284                 memcpy(ptr + 1, offset, tmp - offset);
 285                 ptr += tmp - offset + 1;
 286
 287                 offset = tmp + 1;
 288         }
 289
 290         offset = (char *) domain;
 291         while (offset != NULL) {
 292                 char *tmp;
 293
 294                 tmp = strchr(offset, '.');
 295                 if (tmp == NULL) {
 296                         if (strlen(offset) == 0)
 297                                 break;
 298                         *ptr = strlen(offset);
 299                         memcpy(ptr + 1, offset, strlen(offset));
 300                         ptr += strlen(offset) + 1;
 301                         break;
 302                 }
 303
 304                 *ptr = tmp - offset;
 305                 memcpy(ptr + 1, offset, tmp - offset);
 306                 ptr += tmp - offset + 1;
 307
 308                 offset = tmp + 1;
 309         }
 310
 311         *ptr++ = 0x00;
 312
 313         return ptr - buf;
 314 }
 315
 316 static int ns_resolv(struct server_data *server, struct request_data *req,
 317                                 gpointer request, gpointer name)
 318 {
 319         GList *list;
 320         int sk, err;
 321
 322         sk = g_io_channel_unix_get_fd(server->channel);
 323
 324         err = send(sk, request, req->request_len, 0);
 325
 326         req->numserv++;
 327
 328         for (list = server->domains; list; list = list->next) {
 329                 char *domain;
 330                 unsigned char alt[1024];
 331                 struct domain_hdr *hdr = (void *) &alt;
 332                 int altlen, domlen, offset;
 333
 334                 domain = list->data;
 335
 336                 if (domain == NULL)
 337                         continue;
 338
 339                 offset = protocol_offset(server->protocol);
 340                 if (offset < 0)
 341                         return offset;
 342
 343                 domlen = strlen(domain) + 1;
 344                 if (domlen < 5)
 345                         return -EINVAL;
 346
 347                 alt[offset] = req->altid & 0xff;
 348                 alt[offset + 1] = req->altid >> 8;
 349
 350                 memcpy(alt + offset + 2, request + offset + 2, 10);
 351                 hdr->qdcount = htons(1);
 352
 353                 altlen = append_query(alt + offset + 12, sizeof(alt) - 12,
 354                                         name, domain);
 355                 if (altlen < 0)
 356                         return -EINVAL;
 357
 358                 altlen += 12;
 359
 360                 memcpy(alt + offset + altlen,
 361                         request + offset + altlen - domlen,
 362                                 req->request_len - altlen + domlen);
 363
 364                 if (server->protocol == IPPROTO_TCP) {
 365                         int req_len = req->request_len + domlen - 1;
 366
 367                         alt[0] = (req_len >> 8) & 0xff;
 368                         alt[1] = req_len & 0xff;
 369                 }
 370
 371                 err = send(sk, alt, req->request_len + domlen + 1, 0);
 372
 373                 req->numserv++;
 374         }
 375
 376         return 0;
 377 }
 378
 379 static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol)
 380 {
 381         struct domain_hdr *hdr;
 382         struct request_data *req;
 383         int dns_id, sk, err, offset = protocol_offset(protocol);
 384
 385         if (offset < 0)
 386                 return offset;
 387
 388         hdr = (void *)(reply + offset);
 389         dns_id = reply[offset] | reply[offset + 1] << 8;
 390
 391         DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id);
 392
 393         req = find_request(dns_id);
 394         if (req == NULL)
 395                 return -EINVAL;
 396
 397         DBG("id 0x%04x rcode %d", hdr->id, hdr->rcode);
 398
 399         reply[offset] = req->srcid & 0xff;
 400         reply[offset + 1] = req->srcid >> 8;
 401
 402         req->numresp++;
 403
 404         if (hdr->rcode == 0 || req->resp == NULL) {
 405                 g_free(req->resp);
 406                 req->resplen = 0;
 407
 408                 req->resp = g_try_malloc(reply_len);
 409                 if (req->resp == NULL)
 410                         return -ENOMEM;
 411
 412                 memcpy(req->resp, reply, reply_len);
 413                 req->resplen = reply_len;
 414         }
 415
 416         if (hdr->rcode > 0 && req->numresp < req->numserv)
 417                 return -EINVAL;
 418
 419         if (req->timeout > 0)
 420                 g_source_remove(req->timeout);
 421
 422         request_list = g_slist_remove(request_list, req);
 423
 424         if (protocol == IPPROTO_UDP) {
 425                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 426                 err = sendto(sk, req->resp, req->resplen, 0,
 427                              &req->sa, req->sa_len);
 428         } else {
 429                 sk = req->client_sk;
 430                 err = send(sk, req->resp, req->resplen, 0);
 431                 close(sk);
 432         }
 433
 434         g_free(req->resp);
 435         g_free(req);
 436
 437         return err;
 438 }
 439
 440 static void destroy_server(struct server_data *server)
 441 {
 442         GList *list;
 443
 444         DBG("interface %s server %s", server->interface, server->server);
 445
 446         server_list = g_slist_remove(server_list, server);
 447
 448         if (server->watch > 0)
 449                 g_source_remove(server->watch);
 450
 451         if (server->timeout > 0)
 452                 g_source_remove(server->timeout);
 453
 454         g_io_channel_unref(server->channel);
 455
 456         if (server->protocol == IPPROTO_UDP)
 457                 connman_info("Removing DNS server %s", server->server);
 458
 459         g_free(server->incoming_reply);
 460         g_free(server->server);
 461         for (list = server->domains; list; list = list->next) {
 462                 char *domain = list->data;
 463
 464                 server->domains = g_list_remove(server->domains, domain);
 465                 g_free(domain);
 466         }
 467         g_free(server->interface);
 468         g_free(server);
 469 }
 470
 471 static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition,
 472                                                         gpointer user_data)
 473 {
 474         unsigned char buf[4096];
 475         int sk, err, len;
 476
 477         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 478                 struct server_data *data = user_data;
 479
 480                 connman_error("Error with UDP server %s", data->server);
 481                 data->watch = 0;
 482                 return FALSE;
 483         }
 484
 485         sk = g_io_channel_unix_get_fd(channel);
 486
 487         len = recv(sk, buf, sizeof(buf), 0);
 488         if (len < 12)
 489                 return TRUE;
 490
 491         err = forward_dns_reply(buf, len, IPPROTO_UDP);
 492
 493         return TRUE;
 494 }
 495
 496 static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition,
 497                                                         gpointer user_data)
 498 {
 499         int sk;
 500         struct server_data *server = user_data;
 501
 502         sk = g_io_channel_unix_get_fd(channel);
 503         if (sk == 0)
 504                 return FALSE;
 505
 506         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 507                 GSList *list;
 508 hangup:
 509                 DBG("TCP server channel closed");
 510
 511                 /*
 512                  * Discard any partial response which is buffered; better
 513                  * to get a proper response from a working server.
 514                  */
 515                 g_free(server->incoming_reply);
 516                 server->incoming_reply = NULL;
 517
 518                 for (list = request_list; list; list = list->next) {
 519                         struct request_data *req = list->data;
 520                         struct domain_hdr *hdr;
 521
 522                         if (req->protocol == IPPROTO_UDP)
 523                                 continue;
 524
 525                         if (req->request == NULL)
 526                                 continue;
 527
 528                         /*
 529                          * If we're not waiting for any further response
 530                          * from another name server, then we send an error
 531                          * response to the client.
 532                          */
 533                         if (req->numserv && --(req->numserv))
 534                                 continue;
 535
 536                         hdr = (void *) (req->request + 2);
 537                         hdr->id = req->srcid;
 538                         send_response(req->client_sk, req->request,
 539                                         req->request_len, NULL, 0, IPPROTO_TCP);
 540
 541                         request_list = g_slist_remove(request_list, req);
 542                 }
 543
 544                 destroy_server(server);
 545
 546                 return FALSE;
 547         }
 548
 549         if ((condition & G_IO_OUT) && !server->connected) {
 550                 GSList *list;
 551                 GList *domains;
 552                 struct server_data *udp_server;
 553
 554                 udp_server = find_server(server->interface, server->server,
 555                                                                 IPPROTO_UDP);
 556                 if (udp_server != NULL) {
 557                         for (domains = udp_server->domains; domains;
 558                                                 domains = domains->next) {
 559                                 char *dom = domains->data;
 560
 561                                 DBG("Adding domain %s to %s",
 562                                                 dom, server->server);
 563
 564                                 server->domains = g_list_append(server->domains,
 565                                                                 g_strdup(dom));
 566                         }
 567                 }
 568
 569                 server->connected = TRUE;
 570                 server_list = g_slist_append(server_list, server);
 571
 572                 if (server->timeout > 0) {
 573                         g_source_remove(server->timeout);
 574                         server->timeout = 0;
 575                 }
 576
 577                 for (list = request_list; list; list = list->next) {
 578                         struct request_data *req = list->data;
 579
 580                         if (req->protocol == IPPROTO_UDP)
 581                                 continue;
 582
 583                         DBG("Sending req %s over TCP", (char *)req->name);
 584
 585                         if (req->timeout > 0)
 586                                 g_source_remove(req->timeout);
 587
 588                         req->timeout = g_timeout_add_seconds(30,
 589                                                 request_timeout, req);
 590                         ns_resolv(server, req, req->request, req->name);
 591                 }
 592
 593         } else if (condition & G_IO_IN) {
 594                 struct partial_reply *reply = server->incoming_reply;
 595                 int bytes_recv;
 596
 597                 if (!reply) {
 598                         unsigned char reply_len_buf[2];
 599                         uint16_t reply_len;
 600
 601                         bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK);
 602                         if (!bytes_recv) {
 603                                 goto hangup;
 604                         } else if (bytes_recv < 0) {
 605                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 606                                         return TRUE;
 607
 608                                 connman_error("DNS proxy error %s",
 609                                                 strerror(errno));
 610                                 goto hangup;
 611                         } else if (bytes_recv < 2)
 612                                 return TRUE;
 613
 614                         reply_len = reply_len_buf[1] | reply_len_buf[0] << 8;
 615                         reply_len += 2;
 616
 617                         DBG("TCP reply %d bytes", reply_len);
 618
 619                         reply = g_try_malloc(sizeof(*reply) + reply_len + 2);
 620                         if (!reply)
 621                                 return TRUE;
 622
 623                         reply->len = reply_len;
 624                         reply->received = 0;
 625
 626                         server->incoming_reply = reply;
 627                 }
 628
 629                 while (reply->received < reply->len) {
 630                         bytes_recv = recv(sk, reply->buf + reply->received,
 631                                         reply->len - reply->received, 0);
 632                         if (!bytes_recv) {
 633                                 connman_error("DNS proxy TCP disconnect");
 634                                 break;
 635                         } else if (bytes_recv < 0) {
 636                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 637                                         return TRUE;
 638
 639                                 connman_error("DNS proxy error %s",
 640                                                 strerror(errno));
 641                                 break;
 642                         }
 643                         reply->received += bytes_recv;
 644                 }
 645
 646                 forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP);
 647
 648                 g_free(reply);
 649                 server->incoming_reply = NULL;
 650
 651                 destroy_server(server);
 652
 653                 return FALSE;
 654         }
 655
 656         return TRUE;
 657 }
 658
 659 static gboolean tcp_idle_timeout(gpointer user_data)
 660 {
 661         struct server_data *server = user_data;
 662
 663         DBG("");
 664
 665         if (server == NULL)
 666                 return FALSE;
 667
 668         destroy_server(server);
 669
 670         return FALSE;
 671 }
 672
 673 static struct server_data *create_server(const char *interface,
 674                                         const char *domain, const char *server,
 675                                         int protocol)
 676 {
 677         struct addrinfo hints, *rp;
 678         struct server_data *data;
 679         int sk, ret;
 680
 681         DBG("interface %s server %s", interface, server);
 682
 683         memset(&hints, 0, sizeof(hints));
 684
 685         switch (protocol) {
 686         case IPPROTO_UDP:
 687                 hints.ai_socktype = SOCK_DGRAM;
 688                 break;
 689
 690         case IPPROTO_TCP:
 691                 hints.ai_socktype = SOCK_STREAM;
 692                 break;
 693
 694         default:
 695                 return NULL;
 696         }
 697         hints.ai_family = AF_UNSPEC;
 698         hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
 699
 700         ret = getaddrinfo(server, "53", &hints, &rp);
 701         if (ret) {
 702                 connman_error("Failed to parse server %s address: %s\n",
 703                               server, gai_strerror(ret));
 704                 return NULL;
 705         }
 706         /* Do not blindly copy this code elsewhere; it doesn't loop over the
 707            results using ->ai_next as it should. That's OK in *this* case
 708            because it was a numeric lookup; we *know* there's only one. */
 709
 710         sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 711         if (sk < 0) {
 712                 connman_error("Failed to create server %s socket", server);
 713                 freeaddrinfo(rp);
 714                 return NULL;
 715         }
 716
 717         if (interface != NULL) {
 718                 if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
 719                                 interface, strlen(interface) + 1) < 0) {
 720                         connman_error("Failed to bind server %s "
 721                                                 "to interface %s",
 722                                                         server, interface);
 723                         freeaddrinfo(rp);
 724                         close(sk);
 725                         return NULL;
 726                 }
 727         }
 728
 729         data = g_try_new0(struct server_data, 1);
 730         if (data == NULL) {
 731                 connman_error("Failed to allocate server %s data", server);
 732                 freeaddrinfo(rp);
 733                 close(sk);
 734                 return NULL;
 735         }
 736
 737         data->channel = g_io_channel_unix_new(sk);
 738         if (data->channel == NULL) {
 739                 connman_error("Failed to create server %s channel", server);
 740                 freeaddrinfo(rp);
 741                 close(sk);
 742                 g_free(data);
 743                 return NULL;
 744         }
 745
 746         g_io_channel_set_close_on_unref(data->channel, TRUE);
 747
 748         if (protocol == IPPROTO_TCP) {
 749                 g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL);
 750                 data->watch = g_io_add_watch(data->channel,
 751                         G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR,
 752                                                 tcp_server_event, data);
 753                 data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout,
 754                                                                 data);
 755         } else
 756                 data->watch = g_io_add_watch(data->channel,
 757                         G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 758                                                 udp_server_event, data);
 759
 760         data->interface = g_strdup(interface);
 761         if (domain)
 762                 data->domains = g_list_append(data->domains, g_strdup(domain));
 763         data->server = g_strdup(server);
 764         data->protocol = protocol;
 765
 766         ret = connect(sk, rp->ai_addr, rp->ai_addrlen);
 767         freeaddrinfo(rp);
 768         if (ret < 0) {
 769                 if ((protocol == IPPROTO_TCP && errno != EINPROGRESS) ||
 770                                 protocol == IPPROTO_UDP) {
 771                         GList *list;
 772
 773                         connman_error("Failed to connect to server %s", server);
 774                         if (data->watch > 0)
 775                                 g_source_remove(data->watch);
 776                         if (data->timeout > 0)
 777                                 g_source_remove(data->timeout);
 778
 779                         g_io_channel_unref(data->channel);
 780                         close(sk);
 781
 782                         g_free(data->server);
 783                         g_free(data->interface);
 784                         for (list = data->domains; list; list = list->next) {
 785                                 char *domain = list->data;
 786
 787                                 data->domains = g_list_remove(data->domains,
 788                                                                         domain);
 789                                 g_free(domain);
 790                         }
 791                         g_free(data);
 792                         return NULL;
 793                 }
 794         }
 795
 796         if (protocol == IPPROTO_UDP) {
 797                 /* Enable new servers by default */
 798                 data->enabled = TRUE;
 799                 connman_info("Adding DNS server %s", data->server);
 800
 801                 server_list = g_slist_append(server_list, data);
 802
 803                 return data;
 804         }
 805
 806         return NULL;
 807 }
 808
 809 static gboolean resolv(struct request_data *req,
 810                                 gpointer request, gpointer name)
 811 {
 812         GSList *list;
 813
 814         for (list = server_list; list; list = list->next) {
 815                 struct server_data *data = list->data;
 816
 817                 DBG("server %s enabled %d", data->server, data->enabled);
 818
 819                 if (data->enabled == FALSE)
 820                         continue;
 821
 822                 if (data->watch == 0 && data->protocol == IPPROTO_UDP)
 823                         data->watch = g_io_add_watch(data->channel,
 824                                 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 825                                                 udp_server_event, data);
 826
 827                 if (ns_resolv(data, req, request, name) < 0)
 828                         continue;
 829         }
 830
 831         return TRUE;
 832 }
 833
 834 static void append_domain(const char *interface, const char *domain)
 835 {
 836         GSList *list;
 837
 838         DBG("interface %s domain %s", interface, domain);
 839
 840         for (list = server_list; list; list = list->next) {
 841                 struct server_data *data = list->data;
 842                 GList *dom_list;
 843                 char *dom;
 844                 gboolean dom_found = FALSE;
 845
 846                 if (data->interface == NULL)
 847                         continue;
 848
 849                 if (g_str_equal(data->interface, interface) == FALSE)
 850                         continue;
 851
 852                 for (dom_list = data->domains; dom_list;
 853                                 dom_list = dom_list->next) {
 854                         dom = dom_list->data;
 855
 856                         if (g_str_equal(dom, domain)) {
 857                                 dom_found = TRUE;
 858                                 break;
 859                         }
 860                 }
 861
 862                 if (dom_found == FALSE) {
 863                         data->domains =
 864                                 g_list_append(data->domains, g_strdup(domain));
 865                 }
 866         }
 867 }
 868
 869 int __connman_dnsproxy_append(const char *interface, const char *domain,
 870                                                         const char *server)
 871 {
 872         struct server_data *data;
 873
 874         DBG("interface %s server %s", interface, server);
 875
 876         if (server == NULL && domain == NULL)
 877                 return -EINVAL;
 878
 879         if (server == NULL) {
 880                 append_domain(interface, domain);
 881
 882                 return 0;
 883         }
 884
 885         if (g_str_equal(server, "127.0.0.1") == TRUE)
 886                 return -ENODEV;
 887
 888         data = find_server(interface, server, IPPROTO_UDP);
 889         if (data != NULL) {
 890                 append_domain(interface, domain);
 891                 return 0;
 892         }
 893
 894         data = create_server(interface, domain, server, IPPROTO_UDP);
 895         if (data == NULL)
 896                 return -EIO;
 897
 898         return 0;
 899 }
 900
 901 static void remove_server(const char *interface, const char *domain,
 902                         const char *server, int protocol)
 903 {
 904         struct server_data *data;
 905
 906         data = find_server(interface, server, protocol);
 907         if (data == NULL)
 908                 return;
 909
 910         destroy_server(data);
 911 }
 912
 913 int __connman_dnsproxy_remove(const char *interface, const char *domain,
 914                                                         const char *server)
 915 {
 916         DBG("interface %s server %s", interface, server);
 917
 918         if (server == NULL)
 919                 return -EINVAL;
 920
 921         if (g_str_equal(server, "127.0.0.1") == TRUE)
 922                 return -ENODEV;
 923
 924         remove_server(interface, domain, server, IPPROTO_UDP);
 925         remove_server(interface, domain, server, IPPROTO_TCP);
 926
 927         return 0;
 928 }
 929
 930 void __connman_dnsproxy_flush(void)
 931 {
 932         GSList *list;
 933
 934         list = request_pending_list;
 935         while (list) {
 936                 struct request_data *req = list->data;
 937
 938                 list = list->next;
 939
 940                 request_pending_list =
 941                                 g_slist_remove(request_pending_list, req);
 942                 resolv(req, req->request, req->name);
 943                 g_free(req->request);
 944                 g_free(req->name);
 945         }
 946 }
 947
 948 static void dnsproxy_offline_mode(connman_bool_t enabled)
 949 {
 950         GSList *list;
 951
 952         DBG("enabled %d", enabled);
 953
 954         for (list = server_list; list; list = list->next) {
 955                 struct server_data *data = list->data;
 956
 957                 if (enabled == FALSE) {
 958                         connman_info("Enabling DNS server %s", data->server);
 959                         data->enabled = TRUE;
 960                 } else {
 961                         connman_info("Disabling DNS server %s", data->server);
 962                         data->enabled = FALSE;
 963                 }
 964         }
 965 }
 966
 967 static void dnsproxy_default_changed(struct connman_service *service)
 968 {
 969         GSList *list;
 970         char *interface;
 971
 972         DBG("service %p", service);
 973
 974         if (service == NULL) {
 975                 /* When no services are active, then disable DNS proxying */
 976                 dnsproxy_offline_mode(TRUE);
 977                 return;
 978         }
 979
 980         interface = connman_service_get_interface(service);
 981         if (interface == NULL)
 982                 return;
 983
 984         for (list = server_list; list; list = list->next) {
 985                 struct server_data *data = list->data;
 986
 987                 if (g_strcmp0(data->interface, interface) == 0) {
 988                         connman_info("Enabling DNS server %s", data->server);
 989                         data->enabled = TRUE;
 990                 } else {
 991                         connman_info("Disabling DNS server %s", data->server);
 992                         data->enabled = FALSE;
 993                 }
 994         }
 995
 996         g_free(interface);
 997 }
 998
 999 static struct connman_notifier dnsproxy_notifier = {
1000         .name                   = "dnsproxy",
1001         .default_changed        = dnsproxy_default_changed,
1002         .offline_mode           = dnsproxy_offline_mode,
1003 };
1004
1005 static unsigned char opt_edns0_type[2] = { 0x00, 0x29 };
1006
1007 static int parse_request(unsigned char *buf, int len,
1008                                         char *name, unsigned int size)
1009 {
1010         struct domain_hdr *hdr = (void *) buf;
1011         uint16_t qdcount = ntohs(hdr->qdcount);
1012         uint16_t arcount = ntohs(hdr->arcount);
1013         unsigned char *ptr;
1014         char *last_label = NULL;
1015         unsigned int remain, used = 0;
1016
1017         if (len < 12)
1018                 return -EINVAL;
1019
1020         DBG("id 0x%04x qr %d opcode %d qdcount %d arcount %d",
1021                                         hdr->id, hdr->qr, hdr->opcode,
1022                                                         qdcount, arcount);
1023
1024         if (hdr->qr != 0 || qdcount != 1)
1025                 return -EINVAL;
1026
1027         memset(name, 0, size);
1028
1029         ptr = buf + sizeof(struct domain_hdr);
1030         remain = len - sizeof(struct domain_hdr);
1031
1032         while (remain > 0) {
1033                 uint8_t len = *ptr;
1034
1035                 if (len == 0x00) {
1036                         last_label = (char *) (ptr + 1);
1037                         break;
1038                 }
1039
1040                 if (used + len + 1 > size)
1041                         return -ENOBUFS;
1042
1043                 strncat(name, (char *) (ptr + 1), len);
1044                 strcat(name, ".");
1045
1046                 used += len + 1;
1047
1048                 ptr += len + 1;
1049                 remain -= len + 1;
1050         }
1051
1052         if (last_label && arcount && remain >= 9 && last_label[4] == 0 &&
1053                                 !memcmp(last_label + 5, opt_edns0_type, 2)) {
1054                 uint16_t edns0_bufsize;
1055
1056                 edns0_bufsize = last_label[7] << 8 | last_label[8];
1057
1058                 DBG("EDNS0 buffer size %u", edns0_bufsize);
1059
1060                 /* This is an evil hack until full TCP support has been
1061                  * implemented.
1062                  *
1063                  * Somtimes the EDNS0 request gets send with a too-small
1064                  * buffer size. Since glibc doesn't seem to crash when it
1065                  * gets a response biffer then it requested, just bump
1066                  * the buffer size up to 4KiB.
1067                  */
1068                 if (edns0_bufsize < 0x1000) {
1069                         last_label[7] = 0x10;
1070                         last_label[8] = 0x00;
1071                 }
1072         }
1073
1074         DBG("query %s", name);
1075
1076         return 0;
1077 }
1078
1079 static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
1080                                                         gpointer user_data)
1081 {
1082         unsigned char buf[768];
1083         char query[512];
1084         struct request_data *req;
1085         struct server_data *server;
1086         int sk, client_sk, len, err;
1087         struct sockaddr_in6 client_addr;
1088         socklen_t client_addr_len = sizeof(client_addr);
1089         GSList *list;
1090
1091         DBG("condition 0x%x", condition);
1092
1093         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1094                 if (tcp_listener_watch > 0)
1095                         g_source_remove(tcp_listener_watch);
1096                 tcp_listener_watch = 0;
1097
1098                 connman_error("Error with TCP listener channel");
1099
1100                 return FALSE;
1101         }
1102
1103         sk = g_io_channel_unix_get_fd(channel);
1104
1105         client_sk = accept(sk, (void *)&client_addr, &client_addr_len);
1106         if (client_sk < 0) {
1107                 connman_error("Accept failure on TCP listener");
1108                 tcp_listener_watch = 0;
1109                 return FALSE;
1110         }
1111
1112         len = recv(client_sk, buf, sizeof(buf), 0);
1113         if (len < 2)
1114                 return TRUE;
1115
1116         DBG("Received %d bytes (id 0x%04x)", len, buf[2] | buf[3] << 8);
1117
1118         err = parse_request(buf + 2, len - 2, query, sizeof(query));
1119         if (err < 0 || (g_slist_length(server_list) == 0)) {
1120                 send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP);
1121                 return TRUE;
1122         }
1123
1124         req = g_try_new0(struct request_data, 1);
1125         if (req == NULL)
1126                 return TRUE;
1127
1128         memcpy(&req->sa, &client_addr, client_addr_len);
1129         req->sa_len = client_addr_len;
1130         req->client_sk = client_sk;
1131         req->protocol = IPPROTO_TCP;
1132
1133         request_id += 2;
1134         if (request_id == 0x0000 || request_id == 0xffff)
1135                 request_id += 2;
1136
1137         req->srcid = buf[2] | (buf[3] << 8);
1138         req->dstid = request_id;
1139         req->altid = request_id + 1;
1140         req->request_len = len;
1141
1142         buf[2] = req->dstid & 0xff;
1143         buf[3] = req->dstid >> 8;
1144
1145         req->numserv = 0;
1146         request_list = g_slist_append(request_list, req);
1147
1148         for (list = server_list; list; list = list->next) {
1149                 struct server_data *data = list->data;
1150                 GList *domains;
1151
1152                 if (data->protocol != IPPROTO_UDP || data->enabled == FALSE)
1153                         continue;
1154
1155                 server = create_server(data->interface, NULL,
1156                                         data->server, IPPROTO_TCP);
1157
1158                 /*
1159                  * If server is NULL, we're not connected yet.
1160                  * Copy the relevant buffers and continue with
1161                  * the next nameserver.
1162                  * The request will actually be sent once we're
1163                  * properly connected over TCP to this nameserver.
1164                  */
1165                 if (server == NULL) {
1166                         req->request = g_try_malloc0(req->request_len);
1167                         if (req->request == NULL)
1168                                 return TRUE;
1169
1170                         memcpy(req->request, buf, req->request_len);
1171
1172                         req->name = g_try_malloc0(sizeof(query));
1173                         if (req->name == NULL) {
1174                                 g_free(req->request);
1175                                 return TRUE;
1176                         }
1177                         memcpy(req->name, query, sizeof(query));
1178
1179                         continue;
1180                 }
1181
1182                 if (req->timeout > 0)
1183                         g_source_remove(req->timeout);
1184
1185                 for (domains = data->domains; domains;
1186                                 domains = domains->next) {
1187                         char *dom = domains->data;
1188
1189                         DBG("Adding domain %s to %s", dom, server->server);
1190
1191                         server->domains = g_list_append(server->domains,
1192                                                 g_strdup(dom));
1193                 }
1194
1195                 req->timeout = g_timeout_add_seconds(30, request_timeout, req);
1196                 ns_resolv(server, req, buf, query);
1197         }
1198
1199         return TRUE;
1200 }
1201
1202 static gboolean udp_listener_event(GIOChannel *channel, GIOCondition condition,
1203                                                         gpointer user_data)
1204 {
1205         unsigned char buf[768];
1206         char query[512];
1207         struct request_data *req;
1208         struct sockaddr_in6 client_addr;
1209         socklen_t client_addr_len = sizeof(client_addr);
1210         int sk, err, len;
1211
1212         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1213                 connman_error("Error with UDP listener channel");
1214                 udp_listener_watch = 0;
1215                 return FALSE;
1216         }
1217
1218         sk = g_io_channel_unix_get_fd(channel);
1219
1220         memset(&client_addr, 0, client_addr_len);
1221         len = recvfrom(sk, buf, sizeof(buf), 0, (void *)&client_addr,
1222                        &client_addr_len);
1223         if (len < 2)
1224                 return TRUE;
1225
1226         DBG("Received %d bytes (id 0x%04x)", len, buf[0] | buf[1] << 8);
1227
1228         err = parse_request(buf, len, query, sizeof(query));
1229         if (err < 0 || (g_slist_length(server_list) == 0)) {
1230                 send_response(sk, buf, len, (void *)&client_addr,
1231                               client_addr_len, IPPROTO_UDP);
1232                 return TRUE;
1233         }
1234
1235         req = g_try_new0(struct request_data, 1);
1236         if (req == NULL)
1237                 return TRUE;
1238
1239         memcpy(&req->sa, &client_addr, client_addr_len);
1240         req->sa_len = client_addr_len;
1241         req->client_sk = 0;
1242         req->protocol = IPPROTO_UDP;
1243
1244         request_id += 2;
1245         if (request_id == 0x0000 || request_id == 0xffff)
1246                 request_id += 2;
1247
1248         req->srcid = buf[0] | (buf[1] << 8);
1249         req->dstid = request_id;
1250         req->altid = request_id + 1;
1251         req->request_len = len;
1252
1253         buf[0] = req->dstid & 0xff;
1254         buf[1] = req->dstid >> 8;
1255
1256         req->numserv = 0;
1257         req->timeout = g_timeout_add_seconds(5, request_timeout, req);
1258         request_list = g_slist_append(request_list, req);
1259
1260         return resolv(req, buf, query);
1261 }
1262
1263 static int create_dns_listener(int protocol)
1264 {
1265         GIOChannel *channel;
1266         const char *ifname = "lo", *proto;
1267         union {
1268                 struct sockaddr sa;
1269                 struct sockaddr_in6 sin6;
1270                 struct sockaddr_in sin;
1271         } s;
1272         socklen_t slen;
1273         int sk, type, v6only = 0;
1274         int family = AF_INET6;
1275
1276         DBG("");
1277
1278         switch (protocol) {
1279         case IPPROTO_UDP:
1280                 proto = "UDP";
1281                 type = SOCK_DGRAM;
1282                 break;
1283
1284         case IPPROTO_TCP:
1285                 proto = "TCP";
1286                 type = SOCK_STREAM;
1287                 break;
1288
1289         default:
1290                 return -EINVAL;
1291         }
1292
1293         sk = socket(family, type, protocol);
1294         if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
1295                 connman_error("No IPv6 support; DNS proxy listening only on Legacy IP");
1296                 family = AF_INET;
1297                 sk = socket(family, type, protocol);
1298         }
1299         if (sk < 0) {
1300                 connman_error("Failed to create %s listener socket", proto);
1301                 return -EIO;
1302         }
1303
1304         if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
1305                                         ifname, strlen(ifname) + 1) < 0) {
1306                 connman_error("Failed to bind %s listener interface", proto);
1307                 close(sk);
1308                 return -EIO;
1309         }
1310         /* Ensure it accepts Legacy IP connections too */
1311         if (family == AF_INET6 &&
1312                         setsockopt(sk, SOL_IPV6, IPV6_V6ONLY,
1313                                         &v6only, sizeof(v6only)) < 0) {
1314                 connman_error("Failed to clear V6ONLY on %s listener socket",
1315                               proto);
1316                 close(sk);
1317                 return -EIO;
1318         }
1319
1320         if (family == AF_INET) {
1321                 memset(&s.sin, 0, sizeof(s.sin));
1322                 s.sin.sin_family = AF_INET;
1323                 s.sin.sin_port = htons(53);
1324                 s.sin.sin_addr.s_addr = htonl(INADDR_ANY);
1325                 slen = sizeof(s.sin);
1326         } else {
1327                 memset(&s.sin6, 0, sizeof(s.sin6));
1328                 s.sin6.sin6_family = AF_INET6;
1329                 s.sin6.sin6_port = htons(53);
1330                 s.sin6.sin6_addr = in6addr_any;
1331                 slen = sizeof(s.sin6);
1332         }
1333
1334         if (bind(sk, &s.sa, slen) < 0) {
1335                 connman_error("Failed to bind %s listener socket", proto);
1336                 close(sk);
1337                 return -EIO;
1338         }
1339
1340         if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) {
1341                 connman_error("Failed to listen on TCP socket");
1342                 close(sk);
1343                 return -EIO;
1344         }
1345
1346         channel = g_io_channel_unix_new(sk);
1347         if (channel == NULL) {
1348                 connman_error("Failed to create %s listener channel", proto);
1349                 close(sk);
1350                 return -EIO;
1351         }
1352
1353         g_io_channel_set_close_on_unref(channel, TRUE);
1354
1355         if (protocol == IPPROTO_TCP) {
1356                 tcp_listener_channel = channel;
1357                 tcp_listener_watch = g_io_add_watch(channel,
1358                                         G_IO_IN, tcp_listener_event, NULL);
1359         } else {
1360                 udp_listener_channel = channel;
1361                 udp_listener_watch = g_io_add_watch(channel,
1362                                         G_IO_IN, udp_listener_event, NULL);
1363         }
1364
1365         return 0;
1366 }
1367
1368 static void destroy_udp_listener(void)
1369 {
1370         DBG("");
1371
1372         if (udp_listener_watch > 0)
1373                 g_source_remove(udp_listener_watch);
1374
1375         g_io_channel_unref(udp_listener_channel);
1376 }
1377
1378 static void destroy_tcp_listener(void)
1379 {
1380         DBG("");
1381
1382         if (tcp_listener_watch > 0)
1383                 g_source_remove(tcp_listener_watch);
1384
1385         g_io_channel_unref(tcp_listener_channel);
1386 }
1387
1388 static int create_listener(void)
1389 {
1390         int err;
1391
1392         err = create_dns_listener(IPPROTO_UDP);
1393         if (err < 0)
1394                 return err;
1395
1396         err = create_dns_listener(IPPROTO_TCP);
1397         if (err < 0) {
1398                 destroy_udp_listener();
1399                 return err;
1400         }
1401
1402         __connman_resolvfile_append("lo", NULL, "127.0.0.1");
1403
1404         return 0;
1405 }
1406
1407 static void destroy_listener(void)
1408 {
1409         GSList *list;
1410
1411         __connman_resolvfile_remove("lo", NULL, "127.0.0.1");
1412
1413         for (list = request_pending_list; list; list = list->next) {
1414                 struct request_data *req = list->data;
1415
1416                 DBG("Dropping pending request (id 0x%04x -> 0x%04x)",
1417                                                 req->srcid, req->dstid);
1418
1419                 g_free(req->resp);
1420                 g_free(req->request);
1421                 g_free(req->name);
1422                 g_free(req);
1423                 list->data = NULL;
1424         }
1425
1426         g_slist_free(request_pending_list);
1427         request_pending_list = NULL;
1428
1429         for (list = request_list; list; list = list->next) {
1430                 struct request_data *req = list->data;
1431
1432                 DBG("Dropping request (id 0x%04x -> 0x%04x)",
1433                                                 req->srcid, req->dstid);
1434
1435                 g_free(req->resp);
1436                 g_free(req->request);
1437                 g_free(req->name);
1438                 g_free(req);
1439                 list->data = NULL;
1440         }
1441
1442         g_slist_free(request_list);
1443         request_list = NULL;
1444
1445         destroy_tcp_listener();
1446         destroy_udp_listener();
1447 }
1448
1449 int __connman_dnsproxy_init(connman_bool_t dnsproxy)
1450 {
1451         int err;
1452
1453         DBG("dnsproxy %d", dnsproxy);
1454
1455         dnsproxy_enabled = dnsproxy;
1456         if (dnsproxy_enabled == FALSE)
1457                 return 0;
1458
1459         err = create_listener();
1460         if (err < 0)
1461                 return err;
1462
1463         err = connman_notifier_register(&dnsproxy_notifier);
1464         if (err < 0)
1465                 goto destroy;
1466
1467         return 0;
1468
1469 destroy:
1470         destroy_listener();
1471
1472         return err;
1473 }
1474
1475 void __connman_dnsproxy_cleanup(void)
1476 {
1477         DBG("");
1478
1479         if (dnsproxy_enabled == FALSE)
1480                 return;
1481
1482         connman_notifier_unregister(&dnsproxy_notifier);
1483
1484         destroy_listener();
1485 }