src/dnsproxy.c

   1 /*
   2  *
   3  *  Connection Manager
   4  *
   5  *  Copyright (C) 2007-2010  Intel Corporation. All rights reserved.
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <errno.h>
  27 #include <unistd.h>
  28 #include <string.h>
  29 #include <stdint.h>
  30 #include <arpa/inet.h>
  31 #include <netinet/in.h>
  32 #include <sys/types.h>
  33 #include <sys/socket.h>
  34 #include <netdb.h>
  35
  36 #include <glib.h>
  37
  38 #include "connman.h"
  39
  40 #if __BYTE_ORDER == __LITTLE_ENDIAN
  41 struct domain_hdr {
  42         uint16_t id;
  43         uint8_t rd:1;
  44         uint8_t tc:1;
  45         uint8_t aa:1;
  46         uint8_t opcode:4;
  47         uint8_t qr:1;
  48         uint8_t rcode:4;
  49         uint8_t z:3;
  50         uint8_t ra:1;
  51         uint16_t qdcount;
  52         uint16_t ancount;
  53         uint16_t nscount;
  54         uint16_t arcount;
  55 } __attribute__ ((packed));
  56 #elif __BYTE_ORDER == __BIG_ENDIAN
  57 struct domain_hdr {
  58         uint16_t id;
  59         uint8_t qr:1;
  60         uint8_t opcode:4;
  61         uint8_t aa:1;
  62         uint8_t tc:1;
  63         uint8_t rd:1;
  64         uint8_t ra:1;
  65         uint8_t z:3;
  66         uint8_t rcode:4;
  67         uint16_t qdcount;
  68         uint16_t ancount;
  69         uint16_t nscount;
  70         uint16_t arcount;
  71 } __attribute__ ((packed));
  72 #else
  73 #error "Unknown byte order"
  74 #endif
  75
  76 struct partial_reply {
  77         uint16_t len;
  78         uint16_t received;
  79         unsigned char buf[];
  80 };
  81
  82 struct server_data {
  83         char *interface;
  84         GList *domains;
  85         char *server;
  86         int protocol;
  87         GIOChannel *channel;
  88         guint watch;
  89         guint timeout;
  90         gboolean enabled;
  91         gboolean connected;
  92         struct partial_reply *incoming_reply;
  93 };
  94
  95 struct request_data {
  96         union {
  97                 struct sockaddr_in6 __sin6; /* Only for the length */
  98                 struct sockaddr sa;
  99         };
 100         socklen_t sa_len;
 101         int client_sk;
 102         int protocol;
 103         guint16 srcid;
 104         guint16 dstid;
 105         guint16 altid;
 106         guint timeout;
 107         guint watch;
 108         guint numserv;
 109         guint numresp;
 110         gpointer request;
 111         gsize request_len;
 112         gpointer name;
 113         gpointer resp;
 114         gsize resplen;
 115 };
 116
 117 static GSList *server_list = NULL;
 118 static GSList *request_list = NULL;
 119 static GSList *request_pending_list = NULL;
 120 static guint16 request_id = 0x0000;
 121
 122 static GIOChannel *udp_listener_channel = NULL;
 123 static guint udp_listener_watch = 0;
 124 static GIOChannel *tcp_listener_channel = NULL;
 125 static guint tcp_listener_watch = 0;
 126
 127 static int protocol_offset(int protocol)
 128 {
 129         switch (protocol) {
 130         case IPPROTO_UDP:
 131                 return 0;
 132
 133         case IPPROTO_TCP:
 134                 return 2;
 135
 136         default:
 137                 return -EINVAL;
 138         }
 139
 140 }
 141
 142 static struct request_data *find_request(guint16 id)
 143 {
 144         GSList *list;
 145
 146         for (list = request_list; list; list = list->next) {
 147                 struct request_data *req = list->data;
 148
 149                 if (req->dstid == id || req->altid == id)
 150                         return req;
 151         }
 152
 153         return NULL;
 154 }
 155
 156 static struct server_data *find_server(const char *interface,
 157                                         const char *server,
 158                                                 int protocol)
 159 {
 160         GSList *list;
 161
 162         DBG("interface %s server %s", interface, server);
 163
 164         for (list = server_list; list; list = list->next) {
 165                 struct server_data *data = list->data;
 166
 167                 if (interface == NULL && data->interface == NULL &&
 168                                 g_str_equal(data->server, server) == TRUE &&
 169                                 data->protocol == protocol)
 170                         return data;
 171
 172                 if (interface == NULL ||
 173                                 data->interface == NULL || data->server == NULL)
 174                         continue;
 175
 176                 if (g_str_equal(data->interface, interface) == TRUE &&
 177                                 g_str_equal(data->server, server) == TRUE &&
 178                                 data->protocol == protocol)
 179                         return data;
 180         }
 181
 182         return NULL;
 183 }
 184
 185
 186 static void send_response(int sk, unsigned char *buf, int len,
 187                                 const struct sockaddr *to, socklen_t tolen,
 188                                 int protocol)
 189 {
 190         struct domain_hdr *hdr;
 191         int err, offset = protocol_offset(protocol);
 192
 193         DBG("");
 194
 195         if (offset < 0)
 196                 return;
 197
 198         if (len < 12)
 199                 return;
 200
 201         hdr = (void *) (buf + offset);
 202
 203         DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode);
 204
 205         hdr->qr = 1;
 206         hdr->rcode = 2;
 207
 208         hdr->ancount = 0;
 209         hdr->nscount = 0;
 210         hdr->arcount = 0;
 211
 212         err = sendto(sk, buf, len, 0, to, tolen);
 213 }
 214
 215 static gboolean request_timeout(gpointer user_data)
 216 {
 217         struct request_data *req = user_data;
 218
 219         DBG("id 0x%04x", req->srcid);
 220
 221         if (req == NULL)
 222                 return FALSE;
 223
 224         request_list = g_slist_remove(request_list, req);
 225         req->numserv--;
 226
 227         if (req->resplen > 0 && req->resp != NULL) {
 228                 int sk, err;
 229
 230                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 231
 232                 err = sendto(sk, req->resp, req->resplen, 0,
 233                              &req->sa, req->sa_len);
 234         } else if (req->request && req->numserv == 0) {
 235                 struct domain_hdr *hdr;
 236
 237                 if (req->protocol == IPPROTO_TCP) {
 238                         hdr = (void *) (req->request + 2);
 239                         hdr->id = req->srcid;
 240                         send_response(req->client_sk, req->request,
 241                                         req->request_len, NULL, 0, IPPROTO_TCP);
 242
 243                 } else if (req->protocol == IPPROTO_UDP) {
 244                         int sk;
 245
 246                         hdr = (void *) (req->request);
 247                         hdr->id = req->srcid;
 248                         sk = g_io_channel_unix_get_fd(udp_listener_channel);
 249                         send_response(sk, req->request, req->request_len,
 250                                       &req->sa, req->sa_len, IPPROTO_UDP);
 251                 }
 252         }
 253
 254         g_free(req->resp);
 255         g_free(req);
 256
 257         return FALSE;
 258 }
 259
 260 static int append_query(unsigned char *buf, unsigned int size,
 261                                 const char *query, const char *domain)
 262 {
 263         unsigned char *ptr = buf;
 264         char *offset;
 265
 266         DBG("query %s domain %s", query, domain);
 267
 268         offset = (char *) query;
 269         while (offset != NULL) {
 270                 char *tmp;
 271
 272                 tmp = strchr(offset, '.');
 273                 if (tmp == NULL) {
 274                         if (strlen(offset) == 0)
 275                                 break;
 276                         *ptr = strlen(offset);
 277                         memcpy(ptr + 1, offset, strlen(offset));
 278                         ptr += strlen(offset) + 1;
 279                         break;
 280                 }
 281
 282                 *ptr = tmp - offset;
 283                 memcpy(ptr + 1, offset, tmp - offset);
 284                 ptr += tmp - offset + 1;
 285
 286                 offset = tmp + 1;
 287         }
 288
 289         offset = (char *) domain;
 290         while (offset != NULL) {
 291                 char *tmp;
 292
 293                 tmp = strchr(offset, '.');
 294                 if (tmp == NULL) {
 295                         if (strlen(offset) == 0)
 296                                 break;
 297                         *ptr = strlen(offset);
 298                         memcpy(ptr + 1, offset, strlen(offset));
 299                         ptr += strlen(offset) + 1;
 300                         break;
 301                 }
 302
 303                 *ptr = tmp - offset;
 304                 memcpy(ptr + 1, offset, tmp - offset);
 305                 ptr += tmp - offset + 1;
 306
 307                 offset = tmp + 1;
 308         }
 309
 310         *ptr++ = 0x00;
 311
 312         return ptr - buf;
 313 }
 314
 315 static int ns_resolv(struct server_data *server, struct request_data *req,
 316                                 gpointer request, gpointer name)
 317 {
 318         GList *list;
 319         int sk, err;
 320         char *dot, *lookup = (char *) name;
 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         /* If we have more than one dot, we don't add domains */
 329         dot = strchr(lookup, '.');
 330         if (dot != NULL && dot != lookup + strlen(lookup) - 1)
 331                 return 0;
 332
 333         for (list = server->domains; list; list = list->next) {
 334                 char *domain;
 335                 unsigned char alt[1024];
 336                 struct domain_hdr *hdr = (void *) &alt;
 337                 int altlen, domlen, offset;
 338
 339                 domain = list->data;
 340
 341                 if (domain == NULL)
 342                         continue;
 343
 344                 offset = protocol_offset(server->protocol);
 345                 if (offset < 0)
 346                         return offset;
 347
 348                 domlen = strlen(domain) + 1;
 349                 if (domlen < 5)
 350                         return -EINVAL;
 351
 352                 alt[offset] = req->altid & 0xff;
 353                 alt[offset + 1] = req->altid >> 8;
 354
 355                 memcpy(alt + offset + 2, request + offset + 2, 10);
 356                 hdr->qdcount = htons(1);
 357
 358                 altlen = append_query(alt + offset + 12, sizeof(alt) - 12,
 359                                         name, domain);
 360                 if (altlen < 0)
 361                         return -EINVAL;
 362
 363                 altlen += 12;
 364
 365                 memcpy(alt + offset + altlen,
 366                         request + offset + altlen - domlen,
 367                                 req->request_len - altlen + domlen);
 368
 369                 if (server->protocol == IPPROTO_TCP) {
 370                         int req_len = req->request_len + domlen - 1;
 371
 372                         alt[0] = (req_len >> 8) & 0xff;
 373                         alt[1] = req_len & 0xff;
 374                 }
 375
 376                 err = send(sk, alt, req->request_len + domlen + 1, 0);
 377
 378                 req->numserv++;
 379         }
 380
 381         return 0;
 382 }
 383
 384 static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol)
 385 {
 386         struct domain_hdr *hdr;
 387         struct request_data *req;
 388         int dns_id, sk, err, offset = protocol_offset(protocol);
 389
 390         if (offset < 0)
 391                 return offset;
 392
 393         hdr = (void *)(reply + offset);
 394         dns_id = reply[offset] | reply[offset + 1] << 8;
 395
 396         DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id);
 397
 398         req = find_request(dns_id);
 399         if (req == NULL)
 400                 return -EINVAL;
 401
 402         DBG("id 0x%04x rcode %d", hdr->id, hdr->rcode);
 403
 404         reply[offset] = req->srcid & 0xff;
 405         reply[offset + 1] = req->srcid >> 8;
 406
 407         req->numresp++;
 408
 409         if (hdr->rcode == 0 || req->resp == NULL) {
 410                 g_free(req->resp);
 411                 req->resplen = 0;
 412
 413                 req->resp = g_try_malloc(reply_len);
 414                 if (req->resp == NULL)
 415                         return -ENOMEM;
 416
 417                 memcpy(req->resp, reply, reply_len);
 418                 req->resplen = reply_len;
 419         }
 420
 421         if (hdr->rcode > 0 && req->numresp < req->numserv)
 422                 return -EINVAL;
 423
 424         if (req->timeout > 0)
 425                 g_source_remove(req->timeout);
 426
 427         request_list = g_slist_remove(request_list, req);
 428
 429         if (protocol == IPPROTO_UDP) {
 430                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 431                 err = sendto(sk, req->resp, req->resplen, 0,
 432                              &req->sa, req->sa_len);
 433         } else {
 434                 sk = req->client_sk;
 435                 err = send(sk, req->resp, req->resplen, 0);
 436                 close(sk);
 437         }
 438
 439         g_free(req->resp);
 440         g_free(req);
 441
 442         return err;
 443 }
 444
 445 static void destroy_server(struct server_data *server)
 446 {
 447         GList *list;
 448
 449         DBG("interface %s server %s", server->interface, server->server);
 450
 451         server_list = g_slist_remove(server_list, server);
 452
 453         if (server->watch > 0)
 454                 g_source_remove(server->watch);
 455
 456         if (server->timeout > 0)
 457                 g_source_remove(server->timeout);
 458
 459         g_io_channel_unref(server->channel);
 460
 461         if (server->protocol == IPPROTO_UDP)
 462                 connman_info("Removing DNS server %s", server->server);
 463
 464         g_free(server->incoming_reply);
 465         g_free(server->server);
 466         for (list = server->domains; list; list = list->next) {
 467                 char *domain = list->data;
 468
 469                 server->domains = g_list_remove(server->domains, domain);
 470                 g_free(domain);
 471         }
 472         g_free(server->interface);
 473         g_free(server);
 474 }
 475
 476 static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition,
 477                                                         gpointer user_data)
 478 {
 479         unsigned char buf[4096];
 480         int sk, err, len;
 481
 482         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 483                 struct server_data *data = user_data;
 484
 485                 connman_error("Error with UDP server %s", data->server);
 486                 data->watch = 0;
 487                 return FALSE;
 488         }
 489
 490         sk = g_io_channel_unix_get_fd(channel);
 491
 492         len = recv(sk, buf, sizeof(buf), 0);
 493         if (len < 12)
 494                 return TRUE;
 495
 496         err = forward_dns_reply(buf, len, IPPROTO_UDP);
 497
 498         return TRUE;
 499 }
 500
 501 static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition,
 502                                                         gpointer user_data)
 503 {
 504         int sk;
 505         struct server_data *server = user_data;
 506
 507         sk = g_io_channel_unix_get_fd(channel);
 508         if (sk == 0)
 509                 return FALSE;
 510
 511         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 512                 GSList *list;
 513 hangup:
 514                 DBG("TCP server channel closed");
 515
 516                 /*
 517                  * Discard any partial response which is buffered; better
 518                  * to get a proper response from a working server.
 519                  */
 520                 g_free(server->incoming_reply);
 521                 server->incoming_reply = NULL;
 522
 523                 for (list = request_list; list; list = list->next) {
 524                         struct request_data *req = list->data;
 525                         struct domain_hdr *hdr;
 526
 527                         if (req->protocol == IPPROTO_UDP)
 528                                 continue;
 529
 530                         if (req->request == NULL)
 531                                 continue;
 532
 533                         /*
 534                          * If we're not waiting for any further response
 535                          * from another name server, then we send an error
 536                          * response to the client.
 537                          */
 538                         if (req->numserv && --(req->numserv))
 539                                 continue;
 540
 541                         hdr = (void *) (req->request + 2);
 542                         hdr->id = req->srcid;
 543                         send_response(req->client_sk, req->request,
 544                                         req->request_len, NULL, 0, IPPROTO_TCP);
 545
 546                         request_list = g_slist_remove(request_list, req);
 547                 }
 548
 549                 destroy_server(server);
 550
 551                 return FALSE;
 552         }
 553
 554         if ((condition & G_IO_OUT) && !server->connected) {
 555                 GSList *list;
 556                 GList *domains;
 557                 struct server_data *udp_server;
 558
 559                 udp_server = find_server(server->interface, server->server,
 560                                                                 IPPROTO_UDP);
 561                 if (udp_server != NULL) {
 562                         for (domains = udp_server->domains; domains;
 563                                                 domains = domains->next) {
 564                                 char *dom = domains->data;
 565
 566                                 DBG("Adding domain %s to %s",
 567                                                 dom, server->server);
 568
 569                                 server->domains = g_list_append(server->domains,
 570                                                                 g_strdup(dom));
 571                         }
 572                 }
 573
 574                 server->connected = TRUE;
 575                 server_list = g_slist_append(server_list, server);
 576
 577                 if (server->timeout > 0) {
 578                         g_source_remove(server->timeout);
 579                         server->timeout = 0;
 580                 }
 581
 582                 for (list = request_list; list; list = list->next) {
 583                         struct request_data *req = list->data;
 584
 585                         if (req->protocol == IPPROTO_UDP)
 586                                 continue;
 587
 588                         DBG("Sending req %s over TCP", (char *)req->name);
 589
 590                         if (req->timeout > 0)
 591                                 g_source_remove(req->timeout);
 592
 593                         req->timeout = g_timeout_add_seconds(30,
 594                                                 request_timeout, req);
 595                         ns_resolv(server, req, req->request, req->name);
 596                 }
 597
 598         } else if (condition & G_IO_IN) {
 599                 struct partial_reply *reply = server->incoming_reply;
 600                 int bytes_recv;
 601
 602                 if (!reply) {
 603                         unsigned char reply_len_buf[2];
 604                         uint16_t reply_len;
 605
 606                         bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK);
 607                         if (!bytes_recv) {
 608                                 goto hangup;
 609                         } else if (bytes_recv < 0) {
 610                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 611                                         return TRUE;
 612
 613                                 connman_error("DNS proxy error %s",
 614                                                 strerror(errno));
 615                                 goto hangup;
 616                         } else if (bytes_recv < 2)
 617                                 return TRUE;
 618
 619                         reply_len = reply_len_buf[1] | reply_len_buf[0] << 8;
 620                         reply_len += 2;
 621
 622                         DBG("TCP reply %d bytes", reply_len);
 623
 624                         reply = g_try_malloc(sizeof(*reply) + reply_len + 2);
 625                         if (!reply)
 626                                 return TRUE;
 627
 628                         reply->len = reply_len;
 629                         reply->received = 0;
 630
 631                         server->incoming_reply = reply;
 632                 }
 633
 634                 while (reply->received < reply->len) {
 635                         bytes_recv = recv(sk, reply->buf + reply->received,
 636                                         reply->len - reply->received, 0);
 637                         if (!bytes_recv) {
 638                                 connman_error("DNS proxy TCP disconnect");
 639                                 break;
 640                         } else if (bytes_recv < 0) {
 641                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 642                                         return TRUE;
 643
 644                                 connman_error("DNS proxy error %s",
 645                                                 strerror(errno));
 646                                 break;
 647                         }
 648                         reply->received += bytes_recv;
 649                 }
 650
 651                 forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP);
 652
 653                 g_free(reply);
 654                 server->incoming_reply = NULL;
 655
 656                 destroy_server(server);
 657
 658                 return FALSE;
 659         }
 660
 661         return TRUE;
 662 }
 663
 664 static gboolean tcp_idle_timeout(gpointer user_data)
 665 {
 666         struct server_data *server = user_data;
 667
 668         DBG("");
 669
 670         if (server == NULL)
 671                 return FALSE;
 672
 673         destroy_server(server);
 674
 675         return FALSE;
 676 }
 677
 678 static struct server_data *create_server(const char *interface,
 679                                         const char *domain, const char *server,
 680                                         int protocol)
 681 {
 682         struct addrinfo hints, *rp;
 683         struct server_data *data;
 684         int sk, ret;
 685
 686         DBG("interface %s server %s", interface, server);
 687
 688         memset(&hints, 0, sizeof(hints));
 689
 690         switch (protocol) {
 691         case IPPROTO_UDP:
 692                 hints.ai_socktype = SOCK_DGRAM;
 693                 break;
 694
 695         case IPPROTO_TCP:
 696                 hints.ai_socktype = SOCK_STREAM;
 697                 break;
 698
 699         default:
 700                 return NULL;
 701         }
 702         hints.ai_family = AF_UNSPEC;
 703         hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
 704
 705         ret = getaddrinfo(server, "53", &hints, &rp);
 706         if (ret) {
 707                 connman_error("Failed to parse server %s address: %s\n",
 708                               server, gai_strerror(ret));
 709                 return NULL;
 710         }
 711         /* Do not blindly copy this code elsewhere; it doesn't loop over the
 712            results using ->ai_next as it should. That's OK in *this* case
 713            because it was a numeric lookup; we *know* there's only one. */
 714
 715         sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 716         if (sk < 0) {
 717                 connman_error("Failed to create server %s socket", server);
 718                 freeaddrinfo(rp);
 719                 return NULL;
 720         }
 721
 722         if (interface != NULL) {
 723                 if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
 724                                 interface, strlen(interface) + 1) < 0) {
 725                         connman_error("Failed to bind server %s "
 726                                                 "to interface %s",
 727                                                         server, interface);
 728                         freeaddrinfo(rp);
 729                         close(sk);
 730                         return NULL;
 731                 }
 732         }
 733
 734         data = g_try_new0(struct server_data, 1);
 735         if (data == NULL) {
 736                 connman_error("Failed to allocate server %s data", server);
 737                 freeaddrinfo(rp);
 738                 close(sk);
 739                 return NULL;
 740         }
 741
 742         data->channel = g_io_channel_unix_new(sk);
 743         if (data->channel == NULL) {
 744                 connman_error("Failed to create server %s channel", server);
 745                 freeaddrinfo(rp);
 746                 close(sk);
 747                 g_free(data);
 748                 return NULL;
 749         }
 750
 751         g_io_channel_set_close_on_unref(data->channel, TRUE);
 752
 753         if (protocol == IPPROTO_TCP) {
 754                 g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL);
 755                 data->watch = g_io_add_watch(data->channel,
 756                         G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR,
 757                                                 tcp_server_event, data);
 758                 data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout,
 759                                                                 data);
 760         } else
 761                 data->watch = g_io_add_watch(data->channel,
 762                         G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 763                                                 udp_server_event, data);
 764
 765         data->interface = g_strdup(interface);
 766         if (domain)
 767                 data->domains = g_list_append(data->domains, g_strdup(domain));
 768         data->server = g_strdup(server);
 769         data->protocol = protocol;
 770
 771         ret = connect(sk, rp->ai_addr, rp->ai_addrlen);
 772         freeaddrinfo(rp);
 773         if (ret < 0) {
 774                 if ((protocol == IPPROTO_TCP && errno != EINPROGRESS) ||
 775                                 protocol == IPPROTO_UDP) {
 776                         GList *list;
 777
 778                         connman_error("Failed to connect to server %s", server);
 779                         if (data->watch > 0)
 780                                 g_source_remove(data->watch);
 781                         if (data->timeout > 0)
 782                                 g_source_remove(data->timeout);
 783
 784                         g_io_channel_unref(data->channel);
 785                         close(sk);
 786
 787                         g_free(data->server);
 788                         g_free(data->interface);
 789                         for (list = data->domains; list; list = list->next) {
 790                                 char *domain = list->data;
 791
 792                                 data->domains = g_list_remove(data->domains,
 793                                                                         domain);
 794                                 g_free(domain);
 795                         }
 796                         g_free(data);
 797                         return NULL;
 798                 }
 799         }
 800
 801         if (protocol == IPPROTO_UDP) {
 802                 /* Enable new servers by default */
 803                 data->enabled = TRUE;
 804                 connman_info("Adding DNS server %s", data->server);
 805
 806                 server_list = g_slist_append(server_list, data);
 807
 808                 return data;
 809         }
 810
 811         return NULL;
 812 }
 813
 814 static gboolean resolv(struct request_data *req,
 815                                 gpointer request, gpointer name)
 816 {
 817         GSList *list;
 818
 819         for (list = server_list; list; list = list->next) {
 820                 struct server_data *data = list->data;
 821
 822                 DBG("server %s enabled %d", data->server, data->enabled);
 823
 824                 if (data->enabled == FALSE)
 825                         continue;
 826
 827                 if (data->watch == 0 && data->protocol == IPPROTO_UDP)
 828                         data->watch = g_io_add_watch(data->channel,
 829                                 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 830                                                 udp_server_event, data);
 831
 832                 if (ns_resolv(data, req, request, name) < 0)
 833                         continue;
 834         }
 835
 836         return TRUE;
 837 }
 838
 839 static void append_domain(const char *interface, const char *domain)
 840 {
 841         GSList *list;
 842
 843         DBG("interface %s domain %s", interface, domain);
 844
 845         if (domain == NULL)
 846                 return;
 847
 848         for (list = server_list; list; list = list->next) {
 849                 struct server_data *data = list->data;
 850                 GList *dom_list;
 851                 char *dom;
 852                 gboolean dom_found = FALSE;
 853
 854                 if (data->interface == NULL)
 855                         continue;
 856
 857                 if (g_str_equal(data->interface, interface) == FALSE)
 858                         continue;
 859
 860                 for (dom_list = data->domains; dom_list;
 861                                 dom_list = dom_list->next) {
 862                         dom = dom_list->data;
 863
 864                         if (g_str_equal(dom, domain)) {
 865                                 dom_found = TRUE;
 866                                 break;
 867                         }
 868                 }
 869
 870                 if (dom_found == FALSE) {
 871                         data->domains =
 872                                 g_list_append(data->domains, g_strdup(domain));
 873                 }
 874         }
 875 }
 876
 877 int __connman_dnsproxy_append(const char *interface, const char *domain,
 878                                                         const char *server)
 879 {
 880         struct server_data *data;
 881
 882         DBG("interface %s server %s", interface, server);
 883
 884         if (server == NULL && domain == NULL)
 885                 return -EINVAL;
 886
 887         if (server == NULL) {
 888                 append_domain(interface, domain);
 889
 890                 return 0;
 891         }
 892
 893         if (g_str_equal(server, "127.0.0.1") == TRUE)
 894                 return -ENODEV;
 895
 896         data = find_server(interface, server, IPPROTO_UDP);
 897         if (data != NULL) {
 898                 append_domain(interface, domain);
 899                 return 0;
 900         }
 901
 902         data = create_server(interface, domain, server, IPPROTO_UDP);
 903         if (data == NULL)
 904                 return -EIO;
 905
 906         return 0;
 907 }
 908
 909 static void remove_server(const char *interface, const char *domain,
 910                         const char *server, int protocol)
 911 {
 912         struct server_data *data;
 913
 914         data = find_server(interface, server, protocol);
 915         if (data == NULL)
 916                 return;
 917
 918         destroy_server(data);
 919 }
 920
 921 int __connman_dnsproxy_remove(const char *interface, const char *domain,
 922                                                         const char *server)
 923 {
 924         DBG("interface %s server %s", interface, server);
 925
 926         if (server == NULL)
 927                 return -EINVAL;
 928
 929         if (g_str_equal(server, "127.0.0.1") == TRUE)
 930                 return -ENODEV;
 931
 932         remove_server(interface, domain, server, IPPROTO_UDP);
 933         remove_server(interface, domain, server, IPPROTO_TCP);
 934
 935         return 0;
 936 }
 937
 938 void __connman_dnsproxy_flush(void)
 939 {
 940         GSList *list;
 941
 942         list = request_pending_list;
 943         while (list) {
 944                 struct request_data *req = list->data;
 945
 946                 list = list->next;
 947
 948                 request_pending_list =
 949                                 g_slist_remove(request_pending_list, req);
 950                 resolv(req, req->request, req->name);
 951                 g_free(req->request);
 952                 g_free(req->name);
 953         }
 954 }
 955
 956 static void dnsproxy_offline_mode(connman_bool_t enabled)
 957 {
 958         GSList *list;
 959
 960         DBG("enabled %d", enabled);
 961
 962         for (list = server_list; list; list = list->next) {
 963                 struct server_data *data = list->data;
 964
 965                 if (enabled == FALSE) {
 966                         connman_info("Enabling DNS server %s", data->server);
 967                         data->enabled = TRUE;
 968                 } else {
 969                         connman_info("Disabling DNS server %s", data->server);
 970                         data->enabled = FALSE;
 971                 }
 972         }
 973 }
 974
 975 static void dnsproxy_default_changed(struct connman_service *service)
 976 {
 977         GSList *list;
 978         char *interface;
 979
 980         DBG("service %p", service);
 981
 982         if (service == NULL) {
 983                 /* When no services are active, then disable DNS proxying */
 984                 dnsproxy_offline_mode(TRUE);
 985                 return;
 986         }
 987
 988         interface = connman_service_get_interface(service);
 989         if (interface == NULL)
 990                 return;
 991
 992         for (list = server_list; list; list = list->next) {
 993                 struct server_data *data = list->data;
 994
 995                 if (g_strcmp0(data->interface, interface) == 0) {
 996                         connman_info("Enabling DNS server %s", data->server);
 997                         data->enabled = TRUE;
 998                 } else {
 999                         connman_info("Disabling DNS server %s", data->server);
1000                         data->enabled = FALSE;
1001                 }
1002         }
1003
1004         g_free(interface);
1005 }
1006
1007 static struct connman_notifier dnsproxy_notifier = {
1008         .name                   = "dnsproxy",
1009         .default_changed        = dnsproxy_default_changed,
1010         .offline_mode           = dnsproxy_offline_mode,
1011 };
1012
1013 static unsigned char opt_edns0_type[2] = { 0x00, 0x29 };
1014
1015 static int parse_request(unsigned char *buf, int len,
1016                                         char *name, unsigned int size)
1017 {
1018         struct domain_hdr *hdr = (void *) buf;
1019         uint16_t qdcount = ntohs(hdr->qdcount);
1020         uint16_t arcount = ntohs(hdr->arcount);
1021         unsigned char *ptr;
1022         char *last_label = NULL;
1023         unsigned int remain, used = 0;
1024
1025         if (len < 12)
1026                 return -EINVAL;
1027
1028         DBG("id 0x%04x qr %d opcode %d qdcount %d arcount %d",
1029                                         hdr->id, hdr->qr, hdr->opcode,
1030                                                         qdcount, arcount);
1031
1032         if (hdr->qr != 0 || qdcount != 1)
1033                 return -EINVAL;
1034
1035         memset(name, 0, size);
1036
1037         ptr = buf + sizeof(struct domain_hdr);
1038         remain = len - sizeof(struct domain_hdr);
1039
1040         while (remain > 0) {
1041                 uint8_t len = *ptr;
1042
1043                 if (len == 0x00) {
1044                         last_label = (char *) (ptr + 1);
1045                         break;
1046                 }
1047
1048                 if (used + len + 1 > size)
1049                         return -ENOBUFS;
1050
1051                 strncat(name, (char *) (ptr + 1), len);
1052                 strcat(name, ".");
1053
1054                 used += len + 1;
1055
1056                 ptr += len + 1;
1057                 remain -= len + 1;
1058         }
1059
1060         if (last_label && arcount && remain >= 9 && last_label[4] == 0 &&
1061                                 !memcmp(last_label + 5, opt_edns0_type, 2)) {
1062                 uint16_t edns0_bufsize;
1063
1064                 edns0_bufsize = last_label[7] << 8 | last_label[8];
1065
1066                 DBG("EDNS0 buffer size %u", edns0_bufsize);
1067
1068                 /* This is an evil hack until full TCP support has been
1069                  * implemented.
1070                  *
1071                  * Somtimes the EDNS0 request gets send with a too-small
1072                  * buffer size. Since glibc doesn't seem to crash when it
1073                  * gets a response biffer then it requested, just bump
1074                  * the buffer size up to 4KiB.
1075                  */
1076                 if (edns0_bufsize < 0x1000) {
1077                         last_label[7] = 0x10;
1078                         last_label[8] = 0x00;
1079                 }
1080         }
1081
1082         DBG("query %s", name);
1083
1084         return 0;
1085 }
1086
1087 static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
1088                                                         gpointer user_data)
1089 {
1090         unsigned char buf[768];
1091         char query[512];
1092         struct request_data *req;
1093         struct server_data *server;
1094         int sk, client_sk, len, err;
1095         struct sockaddr_in6 client_addr;
1096         socklen_t client_addr_len = sizeof(client_addr);
1097         GSList *list;
1098
1099         DBG("condition 0x%x", condition);
1100
1101         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1102                 if (tcp_listener_watch > 0)
1103                         g_source_remove(tcp_listener_watch);
1104                 tcp_listener_watch = 0;
1105
1106                 connman_error("Error with TCP listener channel");
1107
1108                 return FALSE;
1109         }
1110
1111         sk = g_io_channel_unix_get_fd(channel);
1112
1113         client_sk = accept(sk, (void *)&client_addr, &client_addr_len);
1114         if (client_sk < 0) {
1115                 connman_error("Accept failure on TCP listener");
1116                 tcp_listener_watch = 0;
1117                 return FALSE;
1118         }
1119
1120         len = recv(client_sk, buf, sizeof(buf), 0);
1121         if (len < 2)
1122                 return TRUE;
1123
1124         DBG("Received %d bytes (id 0x%04x)", len, buf[2] | buf[3] << 8);
1125
1126         err = parse_request(buf + 2, len - 2, query, sizeof(query));
1127         if (err < 0 || (g_slist_length(server_list) == 0)) {
1128                 send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP);
1129                 return TRUE;
1130         }
1131
1132         req = g_try_new0(struct request_data, 1);
1133         if (req == NULL)
1134                 return TRUE;
1135
1136         memcpy(&req->sa, &client_addr, client_addr_len);
1137         req->sa_len = client_addr_len;
1138         req->client_sk = client_sk;
1139         req->protocol = IPPROTO_TCP;
1140
1141         request_id += 2;
1142         if (request_id == 0x0000 || request_id == 0xffff)
1143                 request_id += 2;
1144
1145         req->srcid = buf[2] | (buf[3] << 8);
1146         req->dstid = request_id;
1147         req->altid = request_id + 1;
1148         req->request_len = len;
1149
1150         buf[2] = req->dstid & 0xff;
1151         buf[3] = req->dstid >> 8;
1152
1153         req->numserv = 0;
1154         request_list = g_slist_append(request_list, req);
1155
1156         for (list = server_list; list; list = list->next) {
1157                 struct server_data *data = list->data;
1158                 GList *domains;
1159
1160                 if (data->protocol != IPPROTO_UDP || data->enabled == FALSE)
1161                         continue;
1162
1163                 server = create_server(data->interface, NULL,
1164                                         data->server, IPPROTO_TCP);
1165
1166                 /*
1167                  * If server is NULL, we're not connected yet.
1168                  * Copy the relevant buffers and continue with
1169                  * the next nameserver.
1170                  * The request will actually be sent once we're
1171                  * properly connected over TCP to this nameserver.
1172                  */
1173                 if (server == NULL) {
1174                         req->request = g_try_malloc0(req->request_len);
1175                         if (req->request == NULL)
1176                                 return TRUE;
1177
1178                         memcpy(req->request, buf, req->request_len);
1179
1180                         req->name = g_try_malloc0(sizeof(query));
1181                         if (req->name == NULL) {
1182                                 g_free(req->request);
1183                                 return TRUE;
1184                         }
1185                         memcpy(req->name, query, sizeof(query));
1186
1187                         continue;
1188                 }
1189
1190                 if (req->timeout > 0)
1191                         g_source_remove(req->timeout);
1192
1193                 for (domains = data->domains; domains;
1194                                 domains = domains->next) {
1195                         char *dom = domains->data;
1196
1197                         DBG("Adding domain %s to %s", dom, server->server);
1198
1199                         server->domains = g_list_append(server->domains,
1200                                                 g_strdup(dom));
1201                 }
1202
1203                 req->timeout = g_timeout_add_seconds(30, request_timeout, req);
1204                 ns_resolv(server, req, buf, query);
1205         }
1206
1207         return TRUE;
1208 }
1209
1210 static gboolean udp_listener_event(GIOChannel *channel, GIOCondition condition,
1211                                                         gpointer user_data)
1212 {
1213         unsigned char buf[768];
1214         char query[512];
1215         struct request_data *req;
1216         struct sockaddr_in6 client_addr;
1217         socklen_t client_addr_len = sizeof(client_addr);
1218         int sk, err, len;
1219
1220         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1221                 connman_error("Error with UDP listener channel");
1222                 udp_listener_watch = 0;
1223                 return FALSE;
1224         }
1225
1226         sk = g_io_channel_unix_get_fd(channel);
1227
1228         memset(&client_addr, 0, client_addr_len);
1229         len = recvfrom(sk, buf, sizeof(buf), 0, (void *)&client_addr,
1230                        &client_addr_len);
1231         if (len < 2)
1232                 return TRUE;
1233
1234         DBG("Received %d bytes (id 0x%04x)", len, buf[0] | buf[1] << 8);
1235
1236         err = parse_request(buf, len, query, sizeof(query));
1237         if (err < 0 || (g_slist_length(server_list) == 0)) {
1238                 send_response(sk, buf, len, (void *)&client_addr,
1239                               client_addr_len, IPPROTO_UDP);
1240                 return TRUE;
1241         }
1242
1243         req = g_try_new0(struct request_data, 1);
1244         if (req == NULL)
1245                 return TRUE;
1246
1247         memcpy(&req->sa, &client_addr, client_addr_len);
1248         req->sa_len = client_addr_len;
1249         req->client_sk = 0;
1250         req->protocol = IPPROTO_UDP;
1251
1252         request_id += 2;
1253         if (request_id == 0x0000 || request_id == 0xffff)
1254                 request_id += 2;
1255
1256         req->srcid = buf[0] | (buf[1] << 8);
1257         req->dstid = request_id;
1258         req->altid = request_id + 1;
1259         req->request_len = len;
1260
1261         buf[0] = req->dstid & 0xff;
1262         buf[1] = req->dstid >> 8;
1263
1264         req->numserv = 0;
1265         req->timeout = g_timeout_add_seconds(5, request_timeout, req);
1266         request_list = g_slist_append(request_list, req);
1267
1268         return resolv(req, buf, query);
1269 }
1270
1271 static int create_dns_listener(int protocol)
1272 {
1273         GIOChannel *channel;
1274         const char *ifname = "lo", *proto;
1275         union {
1276                 struct sockaddr sa;
1277                 struct sockaddr_in6 sin6;
1278                 struct sockaddr_in sin;
1279         } s;
1280         socklen_t slen;
1281         int sk, type, v6only = 0;
1282         int family = AF_INET6;
1283
1284         DBG("");
1285
1286         switch (protocol) {
1287         case IPPROTO_UDP:
1288                 proto = "UDP";
1289                 type = SOCK_DGRAM;
1290                 break;
1291
1292         case IPPROTO_TCP:
1293                 proto = "TCP";
1294                 type = SOCK_STREAM;
1295                 break;
1296
1297         default:
1298                 return -EINVAL;
1299         }
1300
1301         sk = socket(family, type, protocol);
1302         if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
1303                 connman_error("No IPv6 support; DNS proxy listening only on Legacy IP");
1304                 family = AF_INET;
1305                 sk = socket(family, type, protocol);
1306         }
1307         if (sk < 0) {
1308                 connman_error("Failed to create %s listener socket", proto);
1309                 return -EIO;
1310         }
1311
1312         if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
1313                                         ifname, strlen(ifname) + 1) < 0) {
1314                 connman_error("Failed to bind %s listener interface", proto);
1315                 close(sk);
1316                 return -EIO;
1317         }
1318         /* Ensure it accepts Legacy IP connections too */
1319         if (family == AF_INET6 &&
1320                         setsockopt(sk, SOL_IPV6, IPV6_V6ONLY,
1321                                         &v6only, sizeof(v6only)) < 0) {
1322                 connman_error("Failed to clear V6ONLY on %s listener socket",
1323                               proto);
1324                 close(sk);
1325                 return -EIO;
1326         }
1327
1328         if (family == AF_INET) {
1329                 memset(&s.sin, 0, sizeof(s.sin));
1330                 s.sin.sin_family = AF_INET;
1331                 s.sin.sin_port = htons(53);
1332                 s.sin.sin_addr.s_addr = htonl(INADDR_ANY);
1333                 slen = sizeof(s.sin);
1334         } else {
1335                 memset(&s.sin6, 0, sizeof(s.sin6));
1336                 s.sin6.sin6_family = AF_INET6;
1337                 s.sin6.sin6_port = htons(53);
1338                 s.sin6.sin6_addr = in6addr_any;
1339                 slen = sizeof(s.sin6);
1340         }
1341
1342         if (bind(sk, &s.sa, slen) < 0) {
1343                 connman_error("Failed to bind %s listener socket", proto);
1344                 close(sk);
1345                 return -EIO;
1346         }
1347
1348         if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) {
1349                 connman_error("Failed to listen on TCP socket");
1350                 close(sk);
1351                 return -EIO;
1352         }
1353
1354         channel = g_io_channel_unix_new(sk);
1355         if (channel == NULL) {
1356                 connman_error("Failed to create %s listener channel", proto);
1357                 close(sk);
1358                 return -EIO;
1359         }
1360
1361         g_io_channel_set_close_on_unref(channel, TRUE);
1362
1363         if (protocol == IPPROTO_TCP) {
1364                 tcp_listener_channel = channel;
1365                 tcp_listener_watch = g_io_add_watch(channel,
1366                                         G_IO_IN, tcp_listener_event, NULL);
1367         } else {
1368                 udp_listener_channel = channel;
1369                 udp_listener_watch = g_io_add_watch(channel,
1370                                         G_IO_IN, udp_listener_event, NULL);
1371         }
1372
1373         return 0;
1374 }
1375
1376 static void destroy_udp_listener(void)
1377 {
1378         DBG("");
1379
1380         if (udp_listener_watch > 0)
1381                 g_source_remove(udp_listener_watch);
1382
1383         g_io_channel_unref(udp_listener_channel);
1384 }
1385
1386 static void destroy_tcp_listener(void)
1387 {
1388         DBG("");
1389
1390         if (tcp_listener_watch > 0)
1391                 g_source_remove(tcp_listener_watch);
1392
1393         g_io_channel_unref(tcp_listener_channel);
1394 }
1395
1396 static int create_listener(void)
1397 {
1398         int err;
1399
1400         err = create_dns_listener(IPPROTO_UDP);
1401         if (err < 0)
1402                 return err;
1403
1404         err = create_dns_listener(IPPROTO_TCP);
1405         if (err < 0) {
1406                 destroy_udp_listener();
1407                 return err;
1408         }
1409
1410         __connman_resolvfile_append("lo", NULL, "127.0.0.1");
1411
1412         return 0;
1413 }
1414
1415 static void destroy_listener(void)
1416 {
1417         GSList *list;
1418
1419         __connman_resolvfile_remove("lo", NULL, "127.0.0.1");
1420
1421         for (list = request_pending_list; list; list = list->next) {
1422                 struct request_data *req = list->data;
1423
1424                 DBG("Dropping pending request (id 0x%04x -> 0x%04x)",
1425                                                 req->srcid, req->dstid);
1426
1427                 g_free(req->resp);
1428                 g_free(req->request);
1429                 g_free(req->name);
1430                 g_free(req);
1431                 list->data = NULL;
1432         }
1433
1434         g_slist_free(request_pending_list);
1435         request_pending_list = NULL;
1436
1437         for (list = request_list; list; list = list->next) {
1438                 struct request_data *req = list->data;
1439
1440                 DBG("Dropping request (id 0x%04x -> 0x%04x)",
1441                                                 req->srcid, req->dstid);
1442
1443                 g_free(req->resp);
1444                 g_free(req->request);
1445                 g_free(req->name);
1446                 g_free(req);
1447                 list->data = NULL;
1448         }
1449
1450         g_slist_free(request_list);
1451         request_list = NULL;
1452
1453         destroy_tcp_listener();
1454         destroy_udp_listener();
1455 }
1456
1457 int __connman_dnsproxy_init(void)
1458 {
1459         int err;
1460
1461         DBG("");
1462
1463         err = create_listener();
1464         if (err < 0)
1465                 return err;
1466
1467         err = connman_notifier_register(&dnsproxy_notifier);
1468         if (err < 0)
1469                 goto destroy;
1470
1471         return 0;
1472
1473 destroy:
1474         destroy_listener();
1475
1476         return err;
1477 }
1478
1479 void __connman_dnsproxy_cleanup(void)
1480 {
1481         DBG("");
1482
1483         connman_notifier_unregister(&dnsproxy_notifier);
1484
1485         destroy_listener();
1486 }