plugins/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 #define CONNMAN_API_SUBJECT_TO_CHANGE
  37 #include <connman/plugin.h>
  38 #include <connman/resolver.h>
  39 #include <connman/notifier.h>
  40 #include <connman/ondemand.h>
  41 #include <connman/log.h>
  42
  43 #include <glib.h>
  44
  45 #if __BYTE_ORDER == __LITTLE_ENDIAN
  46 struct domain_hdr {
  47         uint16_t id;
  48         uint8_t rd:1;
  49         uint8_t tc:1;
  50         uint8_t aa:1;
  51         uint8_t opcode:4;
  52         uint8_t qr:1;
  53         uint8_t rcode:4;
  54         uint8_t z:3;
  55         uint8_t ra:1;
  56         uint16_t qdcount;
  57         uint16_t ancount;
  58         uint16_t nscount;
  59         uint16_t arcount;
  60 } __attribute__ ((packed));
  61 #elif __BYTE_ORDER == __BIG_ENDIAN
  62 struct domain_hdr {
  63         uint16_t id;
  64         uint8_t qr:1;
  65         uint8_t opcode:4;
  66         uint8_t aa:1;
  67         uint8_t tc:1;
  68         uint8_t rd:1;
  69         uint8_t ra:1;
  70         uint8_t z:3;
  71         uint8_t rcode:4;
  72         uint16_t qdcount;
  73         uint16_t ancount;
  74         uint16_t nscount;
  75         uint16_t arcount;
  76 } __attribute__ ((packed));
  77 #else
  78 #error "Unknown byte order"
  79 #endif
  80
  81 struct partial_reply {
  82         uint16_t len;
  83         uint16_t received;
  84         unsigned char buf[];
  85 };
  86
  87 struct server_data {
  88         char *interface;
  89         GList *domains;
  90         char *server;
  91         int protocol;
  92         GIOChannel *channel;
  93         guint watch;
  94         guint timeout;
  95         gboolean enabled;
  96         gboolean connected;
  97         struct partial_reply *incoming_reply;
  98 };
  99
 100 struct request_data {
 101         union {
 102                 struct sockaddr_in6 __sin6; /* Only for the length */
 103                 struct sockaddr sa;
 104         };
 105         socklen_t sa_len;
 106         int client_sk;
 107         int protocol;
 108         guint16 srcid;
 109         guint16 dstid;
 110         guint16 altid;
 111         guint timeout;
 112         guint watch;
 113         guint numserv;
 114         guint numresp;
 115         gpointer request;
 116         gsize request_len;
 117         gpointer name;
 118         gpointer resp;
 119         gsize resplen;
 120 };
 121
 122 static GSList *server_list = NULL;
 123 static GSList *request_list = NULL;
 124 static GSList *request_pending_list = NULL;
 125 static guint16 request_id = 0x0000;
 126
 127 static GIOChannel *udp_listener_channel = NULL;
 128 static guint udp_listener_watch = 0;
 129 static GIOChannel *tcp_listener_channel = NULL;
 130 static guint tcp_listener_watch = 0;
 131
 132 static int protocol_offset(int protocol)
 133 {
 134         switch (protocol) {
 135         case IPPROTO_UDP:
 136                 return 0;
 137
 138         case IPPROTO_TCP:
 139                 return 2;
 140
 141         default:
 142                 return -EINVAL;
 143         }
 144
 145 }
 146
 147 static struct request_data *find_request(guint16 id)
 148 {
 149         GSList *list;
 150
 151         for (list = request_list; list; list = list->next) {
 152                 struct request_data *req = list->data;
 153
 154                 if (req->dstid == id || req->altid == id)
 155                         return req;
 156         }
 157
 158         return NULL;
 159 }
 160
 161 static struct server_data *find_server(const char *interface,
 162                                         const char *server,
 163                                                 int protocol)
 164 {
 165         GSList *list;
 166
 167         DBG("interface %s server %s", interface, server);
 168
 169         for (list = server_list; list; list = list->next) {
 170                 struct server_data *data = list->data;
 171
 172                 if (data->interface == NULL || data->server == NULL)
 173                         continue;
 174
 175                 if (g_str_equal(data->interface, interface) == TRUE &&
 176                                 g_str_equal(data->server, server) == TRUE &&
 177                                 data->protocol == protocol)
 178                         return data;
 179         }
 180
 181         return NULL;
 182 }
 183
 184
 185 static void send_response(int sk, unsigned char *buf, int len,
 186                                 const struct sockaddr *to, socklen_t tolen,
 187                                 int protocol)
 188 {
 189         struct domain_hdr *hdr;
 190         int err, offset = protocol_offset(protocol);
 191
 192         DBG("");
 193
 194         if (offset < 0)
 195                 return;
 196
 197         if (len < 12)
 198                 return;
 199
 200         hdr = (void*) (buf + offset);
 201
 202         DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode);
 203
 204         hdr->qr = 1;
 205         hdr->rcode = 2;
 206
 207         hdr->ancount = 0;
 208         hdr->nscount = 0;
 209         hdr->arcount = 0;
 210
 211         err = sendto(sk, buf, len, 0, to, tolen);
 212 }
 213
 214 static gboolean request_timeout(gpointer user_data)
 215 {
 216         struct request_data *req = user_data;
 217
 218         DBG("id 0x%04x", req->srcid);
 219
 220         if (req == NULL)
 221                 return FALSE;
 222
 223         request_list = g_slist_remove(request_list, req);
 224         req->numserv--;
 225
 226         if (req->resplen > 0 && req->resp != NULL) {
 227                 int sk, err;
 228
 229                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 230
 231                 err = sendto(sk, req->resp, req->resplen, 0,
 232                              &req->sa, req->sa_len);
 233         } else if (req->request && req->numserv == 0) {
 234                 struct domain_hdr *hdr;
 235
 236                 if (req->protocol == IPPROTO_TCP) {
 237                         hdr = (void *) (req->request + 2);
 238                         hdr->id = req->srcid;
 239                         send_response(req->client_sk, req->request,
 240                                         req->request_len, NULL, 0, IPPROTO_TCP);
 241
 242                 } else if (req->protocol == IPPROTO_UDP) {
 243                         int sk;
 244
 245                         hdr = (void *) (req->request);
 246                         hdr->id = req->srcid;
 247                         sk = g_io_channel_unix_get_fd(udp_listener_channel);
 248                         send_response(sk, req->request, req->request_len,
 249                                       &req->sa, req->sa_len, IPPROTO_UDP);
 250                 }
 251         }
 252
 253         g_free(req->resp);
 254         g_free(req);
 255
 256         return FALSE;
 257 }
 258
 259 static int append_query(unsigned char *buf, unsigned int size,
 260                                 const char *query, const char *domain)
 261 {
 262         unsigned char *ptr = buf;
 263         char *offset;
 264
 265         DBG("query %s domain %s", query, domain);
 266
 267         offset = (char *) query;
 268         while (offset != NULL) {
 269                 char *tmp;
 270
 271                 tmp = strchr(offset, '.');
 272                 if (tmp == NULL) {
 273                         if (strlen(offset) == 0)
 274                                 break;
 275                         *ptr = strlen(offset);
 276                         memcpy(ptr + 1, offset, strlen(offset));
 277                         ptr += strlen(offset) + 1;
 278                         break;
 279                 }
 280
 281                 *ptr = tmp - offset;
 282                 memcpy(ptr + 1, offset, tmp - offset);
 283                 ptr += tmp - offset + 1;
 284
 285                 offset = tmp + 1;
 286         }
 287
 288         offset = (char *) domain;
 289         while (offset != NULL) {
 290                 char *tmp;
 291
 292                 tmp = strchr(offset, '.');
 293                 if (tmp == NULL) {
 294                         if (strlen(offset) == 0)
 295                                 break;
 296                         *ptr = strlen(offset);
 297                         memcpy(ptr + 1, offset, strlen(offset));
 298                         ptr += strlen(offset) + 1;
 299                         break;
 300                 }
 301
 302                 *ptr = tmp - offset;
 303                 memcpy(ptr + 1, offset, tmp - offset);
 304                 ptr += tmp - offset + 1;
 305
 306                 offset = tmp + 1;
 307         }
 308
 309         *ptr++ = 0x00;
 310
 311         return ptr - buf;
 312 }
 313
 314 static int ns_resolv(struct server_data *server, struct request_data *req,
 315                                 gpointer request, gpointer name)
 316 {
 317         GList *list;
 318         int sk, err;
 319
 320         sk = g_io_channel_unix_get_fd(server->channel);
 321
 322         err = send(sk, request, req->request_len, 0);
 323
 324         req->numserv++;
 325
 326         for (list = server->domains; list; list = list->next) {
 327                 char *domain;
 328                 unsigned char alt[1024];
 329                 struct domain_hdr *hdr = (void *) &alt;
 330                 int altlen, domlen, offset;
 331
 332                 domain = list->data;
 333
 334                 if (domain == NULL)
 335                         continue;
 336
 337                 offset = protocol_offset(server->protocol);
 338                 if (offset < 0)
 339                         return offset;
 340
 341                 domlen = strlen(domain) + 1;
 342                 if (domlen < 5)
 343                         return -EINVAL;
 344
 345                 alt[offset] = req->altid & 0xff;
 346                 alt[offset + 1] = req->altid >> 8;
 347
 348                 memcpy(alt + offset + 2, request + offset + 2, 10);
 349                 hdr->qdcount = htons(1);
 350
 351                 altlen = append_query(alt + offset + 12, sizeof(alt) - 12,
 352                                         name, domain);
 353                 if (altlen < 0)
 354                         return -EINVAL;
 355
 356                 altlen += 12;
 357
 358                 memcpy(alt + offset + altlen,
 359                         request + offset + altlen - domlen,
 360                                 req->request_len - altlen + domlen);
 361
 362                 if (server->protocol == IPPROTO_TCP) {
 363                         int req_len = req->request_len + domlen - 1;
 364
 365                         alt[0] = (req_len >> 8) & 0xff;
 366                         alt[1] = req_len & 0xff;
 367                 }
 368
 369                 err = send(sk, alt, req->request_len + domlen + 1, 0);
 370
 371                 req->numserv++;
 372         }
 373
 374         return 0;
 375 }
 376
 377 static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol)
 378 {
 379         struct domain_hdr *hdr;
 380         struct request_data *req;
 381         int dns_id, sk, err, offset = protocol_offset(protocol);
 382
 383         if (offset < 0)
 384                 return offset;
 385
 386         hdr = (void *)(reply + offset);
 387         dns_id = reply[offset] | reply[offset + 1] << 8;
 388
 389         DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id);
 390
 391         req = find_request(dns_id);
 392         if (req == NULL)
 393                 return -EINVAL;
 394
 395         DBG("id 0x%04x rcode %d", hdr->id, hdr->rcode);
 396
 397         reply[offset] = req->srcid & 0xff;
 398         reply[offset + 1] = req->srcid >> 8;
 399
 400         req->numresp++;
 401
 402         if (hdr->rcode == 0 || req->resp == NULL) {
 403                 g_free(req->resp);
 404                 req->resplen = 0;
 405
 406                 req->resp = g_try_malloc(reply_len);
 407                 if (req->resp == NULL)
 408                         return -ENOMEM;
 409
 410                 memcpy(req->resp, reply, reply_len);
 411                 req->resplen = reply_len;
 412         }
 413
 414         if (hdr->rcode > 0 && req->numresp < req->numserv)
 415                 return -EINVAL;
 416
 417         if (req->timeout > 0)
 418                 g_source_remove(req->timeout);
 419
 420         request_list = g_slist_remove(request_list, req);
 421
 422         if (protocol == IPPROTO_UDP) {
 423                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 424                 err = sendto(sk, req->resp, req->resplen, 0,
 425                              &req->sa, req->sa_len);
 426         } else {
 427                 sk = req->client_sk;
 428                 err = send(sk, req->resp, req->resplen, 0);
 429                 close(sk);
 430         }
 431
 432         g_free(req->resp);
 433         g_free(req);
 434
 435         return err;
 436 }
 437
 438 static void destroy_server(struct server_data *server)
 439 {
 440         GList *list;
 441
 442         DBG("interface %s server %s", server->interface, server->server);
 443
 444         server_list = g_slist_remove(server_list, server);
 445
 446         if (server->watch > 0)
 447                 g_source_remove(server->watch);
 448
 449         if (server->timeout > 0)
 450                 g_source_remove(server->timeout);
 451
 452         g_io_channel_unref(server->channel);
 453
 454         if (server->protocol == IPPROTO_UDP)
 455                 connman_info("Removing DNS server %s", server->server);
 456
 457         g_free(server->incoming_reply);
 458         g_free(server->server);
 459         for (list = server->domains; list; list = list->next) {
 460                 char *domain = list->data;
 461
 462                 server->domains = g_list_remove(server->domains, domain);
 463                 g_free(domain);
 464         }
 465         g_free(server->interface);
 466         g_free(server);
 467 }
 468
 469 static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition,
 470                                                         gpointer user_data)
 471 {
 472         unsigned char buf[4096];
 473         int sk, err, len;
 474
 475         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 476                 struct server_data *data = user_data;
 477
 478                 connman_error("Error with UDP server %s", data->server);
 479                 data->watch = 0;
 480                 return FALSE;
 481         }
 482
 483         sk = g_io_channel_unix_get_fd(channel);
 484
 485         len = recv(sk, buf, sizeof(buf), 0);
 486         if (len < 12)
 487                 return TRUE;
 488
 489         err = forward_dns_reply(buf, len, IPPROTO_UDP);
 490
 491         return TRUE;
 492 }
 493
 494 static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition,
 495                                                         gpointer user_data)
 496 {
 497         int sk;
 498         struct server_data *server = user_data;
 499
 500         sk = g_io_channel_unix_get_fd(channel);
 501         if (sk == 0)
 502                 return FALSE;
 503
 504         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 505                 GSList *list;
 506         hangup:
 507                 DBG("TCP server channel closed");
 508
 509                 /*
 510                  * Discard any partial response which is buffered; better
 511                  * to get a proper response from a working server.
 512                  */
 513                 g_free(server->incoming_reply);
 514                 server->incoming_reply = NULL;
 515
 516                 for (list = request_list; list; list = list->next) {
 517                         struct request_data *req = list->data;
 518                         struct domain_hdr *hdr;
 519
 520                         if (req->protocol == IPPROTO_UDP)
 521                                 continue;
 522
 523                         if (req->request == NULL)
 524                                 continue;
 525
 526                         /*
 527                          * If we're not waiting for any further response
 528                          * from another name server, then we send an error
 529                          * response to the client.
 530                          */
 531                         if (req->numserv && --(req->numserv))
 532                                 continue;
 533
 534                         hdr = (void *) (req->request + 2);
 535                         hdr->id = req->srcid;
 536                         send_response(req->client_sk, req->request,
 537                                         req->request_len, NULL, 0, IPPROTO_TCP);
 538
 539                         request_list = g_slist_remove(request_list, req);
 540                 }
 541
 542                 destroy_server(server);
 543
 544                 return FALSE;
 545         }
 546
 547         if ((condition & G_IO_OUT) && !server->connected) {
 548                 GSList *list;
 549                 GList *domains;
 550                 struct server_data *udp_server;
 551
 552                 udp_server = find_server(server->interface, server->server,
 553                                                                 IPPROTO_UDP);
 554                 if (udp_server != NULL) {
 555                         for (domains = udp_server->domains; domains;
 556                                                 domains = domains->next) {
 557                                 char *dom = domains->data;
 558
 559                                 DBG("Adding domain %s to %s",
 560                                                 dom, server->server);
 561
 562                                 server->domains = g_list_append(server->domains,
 563                                                                 g_strdup(dom));
 564                         }
 565                 }
 566
 567                 server->connected = TRUE;
 568                 server_list = g_slist_append(server_list, server);
 569
 570                 if (server->timeout > 0) {
 571                         g_source_remove(server->timeout);
 572                         server->timeout = 0;
 573                 }
 574
 575                 for (list = request_list; list; list = list->next) {
 576                         struct request_data *req = list->data;
 577
 578                         if (req->protocol == IPPROTO_UDP)
 579                                 continue;
 580
 581                         DBG("Sending req %s over TCP", (char *)req->name);
 582
 583                         if (req->timeout > 0)
 584                                 g_source_remove(req->timeout);
 585
 586                         req->timeout = g_timeout_add_seconds(30,
 587                                                 request_timeout, req);
 588                         ns_resolv(server, req, req->request, req->name);
 589                 }
 590
 591         } else if (condition & G_IO_IN) {
 592                 struct partial_reply *reply = server->incoming_reply;
 593                 int bytes_recv;
 594
 595                 if (!reply) {
 596                         unsigned char reply_len_buf[2];
 597                         uint16_t reply_len;
 598
 599                         bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK);
 600                         if (!bytes_recv) {
 601                                 goto hangup;
 602                         } else if (bytes_recv < 0) {
 603                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 604                                         return TRUE;
 605
 606                                 connman_error("DNS proxy error %s",
 607                                                 strerror(errno));
 608                                 goto hangup;
 609                         } else if (bytes_recv < 2)
 610                                 return TRUE;
 611
 612                         reply_len = reply_len_buf[1] | reply_len_buf[0] << 8;
 613                         reply_len += 2;
 614
 615                         DBG("TCP reply %d bytes", reply_len);
 616
 617                         reply = g_try_malloc(sizeof(*reply) + reply_len + 2);
 618                         if (!reply)
 619                                 return TRUE;
 620
 621                         reply->len = reply_len;
 622                         reply->received = 0;
 623
 624                         server->incoming_reply = reply;
 625                 }
 626
 627                 while (reply->received < reply->len) {
 628                         bytes_recv = recv(sk, reply->buf + reply->received,
 629                                         reply->len - reply->received, 0);
 630                         if (!bytes_recv) {
 631                                 connman_error("DNS proxy TCP disconnect");
 632                                 break;
 633                         } else if (bytes_recv < 0) {
 634                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 635                                         return TRUE;
 636
 637                                 connman_error("DNS proxy error %s",
 638                                                 strerror(errno));
 639                                 break;
 640                         }
 641                         reply->received += bytes_recv;
 642                 }
 643
 644                 forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP);
 645
 646                 g_free(reply);
 647                 server->incoming_reply = NULL;
 648
 649                 destroy_server(server);
 650
 651                 return FALSE;
 652         }
 653
 654         return TRUE;
 655 }
 656
 657 static gboolean tcp_idle_timeout(gpointer user_data)
 658 {
 659         struct server_data *server = user_data;
 660
 661         DBG("");
 662
 663         if (server == NULL)
 664                 return FALSE;
 665
 666         destroy_server(server);
 667
 668         return FALSE;
 669 }
 670
 671 static struct server_data *create_server(const char *interface,
 672                                         const char *domain, const char *server,
 673                                         int protocol)
 674 {
 675         struct addrinfo hints, *rp;
 676         struct server_data *data;
 677         int sk, ret;
 678
 679         DBG("interface %s server %s", interface, server);
 680
 681         memset(&hints, 0, sizeof(hints));
 682
 683         switch (protocol) {
 684         case IPPROTO_UDP:
 685                 hints.ai_socktype = SOCK_DGRAM;
 686                 break;
 687
 688         case IPPROTO_TCP:
 689                 hints.ai_socktype = SOCK_STREAM;
 690                 break;
 691
 692         default:
 693                 return NULL;
 694         }
 695         hints.ai_family = AF_UNSPEC;
 696         hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
 697
 698         ret = getaddrinfo(server, "53", &hints, &rp);
 699         if (ret) {
 700                 connman_error("Failed to parse server %s address: %s\n",
 701                               server, gai_strerror(ret));
 702                 return NULL;
 703         }
 704         /* Do not blindly copy this code elsewhere; it doesn't loop over the
 705            results using ->ai_next as it should. That's OK in *this* case
 706            because it was a numeric lookup; we *know* there's only one. */
 707
 708         sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 709         if (sk < 0) {
 710                 connman_error("Failed to create server %s socket", server);
 711                 freeaddrinfo(rp);
 712                 return NULL;
 713         }
 714
 715         if (interface != NULL) {
 716                 if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
 717                                 interface, strlen(interface) + 1) < 0) {
 718                         connman_error("Failed to bind server %s "
 719                                                 "to interface %s",
 720                                                         server, interface);
 721                         freeaddrinfo(rp);
 722                         close(sk);
 723                         return NULL;
 724                 }
 725         }
 726
 727         data = g_try_new0(struct server_data, 1);
 728         if (data == NULL) {
 729                 connman_error("Failed to allocate server %s data", server);
 730                 freeaddrinfo(rp);
 731                 close(sk);
 732                 return NULL;
 733         }
 734
 735         data->channel = g_io_channel_unix_new(sk);
 736         if (data->channel == NULL) {
 737                 connman_error("Failed to create server %s channel", server);
 738                 freeaddrinfo(rp);
 739                 close(sk);
 740                 g_free(data);
 741                 return NULL;
 742         }
 743
 744         g_io_channel_set_close_on_unref(data->channel, TRUE);
 745
 746         if (protocol == IPPROTO_TCP) {
 747                 g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL);
 748                 data->watch = g_io_add_watch(data->channel,
 749                         G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR,
 750                                                 tcp_server_event, data);
 751                 data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout,
 752                                                                 data);
 753         } else
 754                 data->watch = g_io_add_watch(data->channel,
 755                         G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 756                                                 udp_server_event, data);
 757
 758         data->interface = g_strdup(interface);
 759         if (domain)
 760                 data->domains = g_list_append(data->domains, g_strdup(domain));
 761         data->server = g_strdup(server);
 762         data->protocol = protocol;
 763
 764         ret = connect(sk, rp->ai_addr, rp->ai_addrlen);
 765         freeaddrinfo(rp);
 766         if (ret < 0) {
 767                 if ((protocol == IPPROTO_TCP && errno != EINPROGRESS) ||
 768                                 protocol == IPPROTO_UDP) {
 769                         GList *list;
 770
 771                         connman_error("Failed to connect to server %s", server);
 772                         close(sk);
 773                         if (data->watch > 0)
 774                                 g_source_remove(data->watch);
 775                         if (data->timeout > 0)
 776                                 g_source_remove(data->timeout);
 777                         g_free(data->server);
 778                         g_free(data->interface);
 779                         for (list = data->domains; list; list = list->next) {
 780                                 char *domain = list->data;
 781
 782                                 data->domains = g_list_remove(data->domains,
 783                                                                         domain);
 784                                 g_free(domain);
 785                         }
 786                         g_free(data);
 787                         return NULL;
 788                 }
 789         }
 790
 791         if (protocol == IPPROTO_UDP) {
 792                 /* Enable new servers by default */
 793                 data->enabled = TRUE;
 794                 connman_info("Adding DNS server %s", data->server);
 795
 796                 server_list = g_slist_append(server_list, data);
 797
 798                 return data;
 799         }
 800
 801         return NULL;
 802 }
 803
 804 static gboolean resolv(struct request_data *req,
 805                                 gpointer request, gpointer name)
 806 {
 807         GSList *list;
 808
 809         for (list = server_list; list; list = list->next) {
 810                 struct server_data *data = list->data;
 811
 812                 DBG("server %s enabled %d", data->server, data->enabled);
 813
 814                 if (data->enabled == FALSE)
 815                         continue;
 816
 817                 if (data->watch == 0 && data->protocol == IPPROTO_UDP)
 818                         data->watch = g_io_add_watch(data->channel,
 819                                 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 820                                                 udp_server_event, data);
 821
 822                 if (ns_resolv(data, req, request, name) < 0)
 823                         continue;
 824         }
 825
 826         return TRUE;
 827 }
 828
 829 static void append_domain(const char *interface, const char *domain)
 830 {
 831         GSList *list;
 832
 833         DBG("interface %s domain %s", interface, domain);
 834
 835         for (list = server_list; list; list = list->next) {
 836                 struct server_data *data = list->data;
 837                 GList *dom_list;
 838                 char *dom;
 839                 gboolean dom_found = FALSE;
 840
 841                 if (data->interface == NULL)
 842                         continue;
 843
 844                 if (g_str_equal(data->interface, interface) == FALSE)
 845                         continue;
 846
 847                 for (dom_list = data->domains; dom_list; 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 = g_list_append(data->domains, g_strdup(domain));
 858         }
 859 }
 860
 861 static int dnsproxy_append(const char *interface, const char *domain,
 862                                                         const char *server)
 863 {
 864         struct server_data *data;
 865
 866         DBG("interface %s server %s", interface, server);
 867
 868         if (server == NULL && domain == NULL)
 869                 return -EINVAL;
 870
 871         if (server == NULL) {
 872                 append_domain(interface, domain);
 873
 874                 return 0;
 875         }
 876
 877         if (g_str_equal(server, "127.0.0.1") == TRUE)
 878                 return -ENODEV;
 879
 880         data = find_server(interface, server, IPPROTO_UDP);
 881         if (data != NULL) {
 882                 append_domain(interface, domain);
 883                 return 0;
 884         }
 885
 886         data = create_server(interface, domain, server, IPPROTO_UDP);
 887         if (data == NULL)
 888                 return -EIO;
 889
 890         return 0;
 891 }
 892
 893 static void remove_server(const char *interface, const char *domain,
 894                         const char *server, int protocol)
 895 {
 896         struct server_data *data;
 897
 898         data = find_server(interface, server, protocol);
 899         if (data == NULL)
 900                 return;
 901
 902         destroy_server(data);
 903 }
 904
 905 static int dnsproxy_remove(const char *interface, const char *domain,
 906                                                         const char *server)
 907 {
 908         DBG("interface %s server %s", interface, server);
 909
 910         if (server == NULL)
 911                 return -EINVAL;
 912
 913         if (g_str_equal(server, "127.0.0.1") == TRUE)
 914                 return -ENODEV;
 915
 916         remove_server(interface, domain, server, IPPROTO_UDP);
 917         remove_server(interface, domain, server, IPPROTO_TCP);
 918
 919         return 0;
 920 }
 921
 922 static void dnsproxy_flush(void)
 923 {
 924         GSList *list;
 925
 926         list = request_pending_list;
 927         while (list) {
 928                 struct request_data *req = list->data;
 929
 930                 list = list->next;
 931
 932                 request_pending_list =
 933                                 g_slist_remove(request_pending_list, req);
 934                 resolv(req, req->request, req->name);
 935                 g_free(req->request);
 936                 g_free(req->name);
 937         }
 938 }
 939
 940 static struct connman_resolver dnsproxy_resolver = {
 941         .name           = "dnsproxy",
 942         .priority       = CONNMAN_RESOLVER_PRIORITY_HIGH,
 943         .append         = dnsproxy_append,
 944         .remove         = dnsproxy_remove,
 945         .flush          = dnsproxy_flush,
 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                                 connman_ondemand_connected())) {
1121                 send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP);
1122                 return TRUE;
1123         }
1124
1125         req = g_try_new0(struct request_data, 1);
1126         if (req == NULL)
1127                 return TRUE;
1128
1129         memcpy(&req->sa, &client_addr, client_addr_len);
1130         req->sa_len = client_addr_len;
1131         req->client_sk = client_sk;
1132         req->protocol = IPPROTO_TCP;
1133
1134         request_id += 2;
1135         if (request_id == 0x0000 || request_id == 0xffff)
1136                 request_id += 2;
1137
1138         req->srcid = buf[2] | (buf[3] << 8);
1139         req->dstid = request_id;
1140         req->altid = request_id + 1;
1141         req->request_len = len;
1142
1143         buf[2] = req->dstid & 0xff;
1144         buf[3] = req->dstid >> 8;
1145
1146         req->numserv = 0;
1147         request_list = g_slist_append(request_list, req);
1148
1149         for (list = server_list; list; list = list->next) {
1150                 struct server_data *data = list->data;
1151                 GList *domains;
1152
1153                 if (data->protocol != IPPROTO_UDP || data->enabled == FALSE)
1154                         continue;
1155
1156                 server = create_server(data->interface, NULL,
1157                                         data->server, IPPROTO_TCP);
1158
1159                 /*
1160                  * If server is NULL, we're not connected yet.
1161                  * Copy the relevant buffers and continue with
1162                  * the next nameserver.
1163                  * The request will actually be sent once we're
1164                  * properly connected over TCP to this nameserver.
1165                  */
1166                 if (server == NULL) {
1167                         req->request = g_try_malloc0(req->request_len);
1168                         if (req->request == NULL)
1169                                 return TRUE;
1170
1171                         memcpy(req->request, buf, req->request_len);
1172
1173                         req->name = g_try_malloc0(sizeof(query));
1174                         if (req->name == NULL) {
1175                                 g_free(req->request);
1176                                 return TRUE;
1177                         }
1178                         memcpy(req->name, query, sizeof(query));
1179
1180                         continue;
1181                 }
1182
1183                 if (req->timeout > 0)
1184                         g_source_remove(req->timeout);
1185
1186                 for (domains = data->domains; domains; 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                                 connman_ondemand_connected())) {
1231                 send_response(sk, buf, len, (void *)&client_addr,
1232                               client_addr_len, IPPROTO_UDP);
1233                 return TRUE;
1234         }
1235
1236         req = g_try_new0(struct request_data, 1);
1237         if (req == NULL)
1238                 return TRUE;
1239
1240         memcpy(&req->sa, &client_addr, client_addr_len);
1241         req->sa_len = client_addr_len;
1242         req->client_sk = 0;
1243         req->protocol = IPPROTO_UDP;
1244
1245         request_id += 2;
1246         if (request_id == 0x0000 || request_id == 0xffff)
1247                 request_id += 2;
1248
1249         req->srcid = buf[0] | (buf[1] << 8);
1250         req->dstid = request_id;
1251         req->altid = request_id + 1;
1252         req->request_len = len;
1253
1254         buf[0] = req->dstid & 0xff;
1255         buf[1] = req->dstid >> 8;
1256
1257         if (!connman_ondemand_connected()) {
1258                 DBG("Starting on demand connection");
1259                 /*
1260                  * We're not connected, let's queue the request and start
1261                  * an on-demand connection.
1262                  */
1263                 req->request = g_try_malloc0(req->request_len);
1264                 if (req->request == NULL)
1265                         return TRUE;
1266
1267                 memcpy(req->request, buf, req->request_len);
1268
1269                 req->name = g_try_malloc0(sizeof(query));
1270                 if (req->name == NULL) {
1271                         g_free(req->request);
1272                         return TRUE;
1273                 }
1274                 memcpy(req->name, query, sizeof(query));
1275
1276                 request_pending_list = g_slist_append(request_pending_list,
1277                                                                         req);
1278
1279                 connman_ondemand_start("", 300);
1280
1281                 return TRUE;
1282         }
1283
1284
1285         req->numserv = 0;
1286         req->timeout = g_timeout_add_seconds(5, request_timeout, req);
1287         request_list = g_slist_append(request_list, req);
1288
1289         return resolv(req, buf, query);
1290 }
1291
1292 static int create_dns_listener(int protocol)
1293 {
1294         GIOChannel *channel;
1295         const char *ifname = "lo", *proto;
1296         union {
1297                 struct sockaddr sa;
1298                 struct sockaddr_in6 sin6;
1299                 struct sockaddr_in sin;
1300         } s;
1301         socklen_t slen;
1302         int sk, type, v6only = 0;
1303         int family = AF_INET6;
1304
1305         DBG("");
1306
1307         switch (protocol) {
1308         case IPPROTO_UDP:
1309                 proto = "UDP";
1310                 type = SOCK_DGRAM;
1311                 break;
1312
1313         case IPPROTO_TCP:
1314                 proto = "TCP";
1315                 type = SOCK_STREAM;
1316                 break;
1317
1318         default:
1319                 return -EINVAL;
1320         }
1321
1322         sk = socket(family, type, protocol);
1323         if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
1324                 connman_error("No IPv6 support; DNS proxy listening only on Legacy IP");
1325                 family = AF_INET;
1326                 sk = socket(family, type, protocol);
1327         }
1328         if (sk < 0) {
1329                 connman_error("Failed to create %s listener socket", proto);
1330                 return -EIO;
1331         }
1332
1333         if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
1334                                         ifname, strlen(ifname) + 1) < 0) {
1335                 connman_error("Failed to bind %s listener interface", proto);
1336                 close(sk);
1337                 return -EIO;
1338         }
1339         /* Ensure it accepts Legacy IP connections too */
1340         if (family == AF_INET6 &&
1341             setsockopt(sk, SOL_IPV6, IPV6_V6ONLY, &v6only, sizeof(v6only)) < 0) {
1342                 connman_error("Failed to clear V6ONLY on %s listener socket",
1343                               proto);
1344                 close(sk);
1345                 return -EIO;
1346         }
1347
1348         if (family == AF_INET) {
1349                 memset(&s.sin, 0, sizeof(s.sin));
1350                 s.sin.sin_family = AF_INET;
1351                 s.sin.sin_port = htons(53);
1352                 s.sin.sin_addr.s_addr = htonl(INADDR_ANY);
1353                 slen = sizeof(s.sin);
1354         } else {
1355                 memset(&s.sin6, 0, sizeof(s.sin6));
1356                 s.sin6.sin6_family = AF_INET6;
1357                 s.sin6.sin6_port = htons(53);
1358                 s.sin6.sin6_addr = in6addr_any;
1359                 slen = sizeof(s.sin6);
1360         }
1361
1362         if (bind(sk, &s.sa, slen) < 0) {
1363                 connman_error("Failed to bind %s listener socket", proto);
1364                 close(sk);
1365                 return -EIO;
1366         }
1367
1368         if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) {
1369                 connman_error("Failed to listen on TCP socket");
1370                 close(sk);
1371                 return -EIO;
1372         }
1373
1374         channel = g_io_channel_unix_new(sk);
1375         if (channel == NULL) {
1376                 connman_error("Failed to create %s listener channel", proto);
1377                 close(sk);
1378                 return -EIO;
1379         }
1380
1381         g_io_channel_set_close_on_unref(channel, TRUE);
1382
1383         if (protocol == IPPROTO_TCP) {
1384                 tcp_listener_channel = channel;
1385                 tcp_listener_watch = g_io_add_watch(channel,
1386                                         G_IO_IN, tcp_listener_event, NULL);
1387         } else {
1388                 udp_listener_channel = channel;
1389                 udp_listener_watch = g_io_add_watch(channel,
1390                                         G_IO_IN, udp_listener_event, NULL);
1391         }
1392
1393         return 0;
1394 }
1395
1396 static void destroy_udp_listener(void)
1397 {
1398         DBG("");
1399
1400         if (udp_listener_watch > 0)
1401                 g_source_remove(udp_listener_watch);
1402
1403         g_io_channel_unref(udp_listener_channel);
1404 }
1405
1406 static void destroy_tcp_listener(void)
1407 {
1408         DBG("");
1409
1410         if (tcp_listener_watch > 0)
1411                 g_source_remove(tcp_listener_watch);
1412
1413         g_io_channel_unref(tcp_listener_channel);
1414 }
1415
1416 static int create_listener(void)
1417 {
1418         int err;
1419
1420         err = create_dns_listener(IPPROTO_UDP);
1421         if (err < 0)
1422                 return err;
1423
1424         err = create_dns_listener(IPPROTO_TCP);
1425         if (err < 0) {
1426                 destroy_udp_listener();
1427                 return err;
1428         }
1429
1430         connman_resolver_append("lo", NULL, "127.0.0.1");
1431
1432         return 0;
1433 }
1434
1435 static void destroy_listener(void)
1436 {
1437         GSList *list;
1438
1439         connman_resolver_remove_all("lo");
1440
1441         for (list = request_pending_list; list; list = list->next) {
1442                 struct request_data *req = list->data;
1443
1444                 DBG("Dropping pending request (id 0x%04x -> 0x%04x)",
1445                                                 req->srcid, req->dstid);
1446
1447                 g_free(req->resp);
1448                 g_free(req->request);
1449                 g_free(req->name);
1450                 g_free(req);
1451                 list->data = NULL;
1452         }
1453
1454         g_slist_free(request_pending_list);
1455         request_pending_list = NULL;
1456
1457         for (list = request_list; list; list = list->next) {
1458                 struct request_data *req = list->data;
1459
1460                 DBG("Dropping request (id 0x%04x -> 0x%04x)",
1461                                                 req->srcid, req->dstid);
1462
1463                 g_free(req->resp);
1464                 g_free(req->request);
1465                 g_free(req->name);
1466                 g_free(req);
1467                 list->data = NULL;
1468         }
1469
1470         g_slist_free(request_list);
1471         request_list = NULL;
1472
1473         destroy_tcp_listener();
1474         destroy_udp_listener();
1475 }
1476
1477 static int dnsproxy_init(void)
1478 {
1479         int err;
1480
1481         err = create_listener();
1482         if (err < 0)
1483                 return err;
1484
1485         err = connman_resolver_register(&dnsproxy_resolver);
1486         if (err < 0)
1487                 goto destroy;
1488
1489         err = connman_notifier_register(&dnsproxy_notifier);
1490         if (err < 0)
1491                 goto unregister;
1492
1493         return 0;
1494
1495 unregister:
1496         connman_resolver_unregister(&dnsproxy_resolver);
1497
1498 destroy:
1499         destroy_listener();
1500
1501         return err;
1502 }
1503
1504 static void dnsproxy_exit(void)
1505 {
1506         connman_notifier_unregister(&dnsproxy_notifier);
1507
1508         connman_resolver_unregister(&dnsproxy_resolver);
1509
1510         destroy_listener();
1511 }
1512
1513 CONNMAN_PLUGIN_DEFINE(dnsproxy, "DNS proxy resolver plugin", VERSION,
1514                  CONNMAN_PLUGIN_PRIORITY_DEFAULT, dnsproxy_init, dnsproxy_exit)