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 #define CONNMAN_API_SUBJECT_TO_CHANGE
  39 #include <connman/ondemand.h>
  40
  41 #include "connman.h"
  42
  43 #if __BYTE_ORDER == __LITTLE_ENDIAN
  44 struct domain_hdr {
  45         uint16_t id;
  46         uint8_t rd:1;
  47         uint8_t tc:1;
  48         uint8_t aa:1;
  49         uint8_t opcode:4;
  50         uint8_t qr:1;
  51         uint8_t rcode:4;
  52         uint8_t z:3;
  53         uint8_t ra:1;
  54         uint16_t qdcount;
  55         uint16_t ancount;
  56         uint16_t nscount;
  57         uint16_t arcount;
  58 } __attribute__ ((packed));
  59 #elif __BYTE_ORDER == __BIG_ENDIAN
  60 struct domain_hdr {
  61         uint16_t id;
  62         uint8_t qr:1;
  63         uint8_t opcode:4;
  64         uint8_t aa:1;
  65         uint8_t tc:1;
  66         uint8_t rd:1;
  67         uint8_t ra:1;
  68         uint8_t z:3;
  69         uint8_t rcode:4;
  70         uint16_t qdcount;
  71         uint16_t ancount;
  72         uint16_t nscount;
  73         uint16_t arcount;
  74 } __attribute__ ((packed));
  75 #else
  76 #error "Unknown byte order"
  77 #endif
  78
  79 struct partial_reply {
  80         uint16_t len;
  81         uint16_t received;
  82         unsigned char buf[];
  83 };
  84
  85 struct server_data {
  86         char *interface;
  87         GList *domains;
  88         char *server;
  89         int protocol;
  90         GIOChannel *channel;
  91         guint watch;
  92         guint timeout;
  93         gboolean enabled;
  94         gboolean connected;
  95         struct partial_reply *incoming_reply;
  96 };
  97
  98 struct request_data {
  99         union {
 100                 struct sockaddr_in6 __sin6; /* Only for the length */
 101                 struct sockaddr sa;
 102         };
 103         socklen_t sa_len;
 104         int client_sk;
 105         int protocol;
 106         guint16 srcid;
 107         guint16 dstid;
 108         guint16 altid;
 109         guint timeout;
 110         guint watch;
 111         guint numserv;
 112         guint numresp;
 113         gpointer request;
 114         gsize request_len;
 115         gpointer name;
 116         gpointer resp;
 117         gsize resplen;
 118 };
 119
 120 static connman_bool_t dnsproxy_enabled = TRUE;
 121 static GSList *server_list = NULL;
 122 static GSList *request_list = NULL;
 123 static GSList *request_pending_list = NULL;
 124 static guint16 request_id = 0x0000;
 125
 126 static GIOChannel *udp_listener_channel = NULL;
 127 static guint udp_listener_watch = 0;
 128 static GIOChannel *tcp_listener_channel = NULL;
 129 static guint tcp_listener_watch = 0;
 130
 131 static int protocol_offset(int protocol)
 132 {
 133         switch (protocol) {
 134         case IPPROTO_UDP:
 135                 return 0;
 136
 137         case IPPROTO_TCP:
 138                 return 2;
 139
 140         default:
 141                 return -EINVAL;
 142         }
 143
 144 }
 145
 146 static struct request_data *find_request(guint16 id)
 147 {
 148         GSList *list;
 149
 150         for (list = request_list; list; list = list->next) {
 151                 struct request_data *req = list->data;
 152
 153                 if (req->dstid == id || req->altid == id)
 154                         return req;
 155         }
 156
 157         return NULL;
 158 }
 159
 160 static struct server_data *find_server(const char *interface,
 161                                         const char *server,
 162                                                 int protocol)
 163 {
 164         GSList *list;
 165
 166         DBG("interface %s server %s", interface, server);
 167
 168         for (list = server_list; list; list = list->next) {
 169                 struct server_data *data = list->data;
 170
 171                 if (data->interface == NULL || data->server == NULL)
 172                         continue;
 173
 174                 if (g_str_equal(data->interface, interface) == TRUE &&
 175                                 g_str_equal(data->server, server) == TRUE &&
 176                                 data->protocol == protocol)
 177                         return data;
 178         }
 179
 180         return NULL;
 181 }
 182
 183
 184 static void send_response(int sk, unsigned char *buf, int len,
 185                                 const struct sockaddr *to, socklen_t tolen,
 186                                 int protocol)
 187 {
 188         struct domain_hdr *hdr;
 189         int err, offset = protocol_offset(protocol);
 190
 191         DBG("");
 192
 193         if (offset < 0)
 194                 return;
 195
 196         if (len < 12)
 197                 return;
 198
 199         hdr = (void *) (buf + offset);
 200
 201         DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode);
 202
 203         hdr->qr = 1;
 204         hdr->rcode = 2;
 205
 206         hdr->ancount = 0;
 207         hdr->nscount = 0;
 208         hdr->arcount = 0;
 209
 210         err = sendto(sk, buf, len, 0, to, tolen);
 211 }
 212
 213 static gboolean request_timeout(gpointer user_data)
 214 {
 215         struct request_data *req = user_data;
 216
 217         DBG("id 0x%04x", req->srcid);
 218
 219         if (req == NULL)
 220                 return FALSE;
 221
 222         request_list = g_slist_remove(request_list, req);
 223         req->numserv--;
 224
 225         if (req->resplen > 0 && req->resp != NULL) {
 226                 int sk, err;
 227
 228                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 229
 230                 err = sendto(sk, req->resp, req->resplen, 0,
 231                              &req->sa, req->sa_len);
 232         } else if (req->request && req->numserv == 0) {
 233                 struct domain_hdr *hdr;
 234
 235                 if (req->protocol == IPPROTO_TCP) {
 236                         hdr = (void *) (req->request + 2);
 237                         hdr->id = req->srcid;
 238                         send_response(req->client_sk, req->request,
 239                                         req->request_len, NULL, 0, IPPROTO_TCP);
 240
 241                 } else if (req->protocol == IPPROTO_UDP) {
 242                         int sk;
 243
 244                         hdr = (void *) (req->request);
 245                         hdr->id = req->srcid;
 246                         sk = g_io_channel_unix_get_fd(udp_listener_channel);
 247                         send_response(sk, req->request, req->request_len,
 248                                       &req->sa, req->sa_len, IPPROTO_UDP);
 249                 }
 250         }
 251
 252         g_free(req->resp);
 253         g_free(req);
 254
 255         return FALSE;
 256 }
 257
 258 static int append_query(unsigned char *buf, unsigned int size,
 259                                 const char *query, const char *domain)
 260 {
 261         unsigned char *ptr = buf;
 262         char *offset;
 263
 264         DBG("query %s domain %s", query, domain);
 265
 266         offset = (char *) query;
 267         while (offset != NULL) {
 268                 char *tmp;
 269
 270                 tmp = strchr(offset, '.');
 271                 if (tmp == NULL) {
 272                         if (strlen(offset) == 0)
 273                                 break;
 274                         *ptr = strlen(offset);
 275                         memcpy(ptr + 1, offset, strlen(offset));
 276                         ptr += strlen(offset) + 1;
 277                         break;
 278                 }
 279
 280                 *ptr = tmp - offset;
 281                 memcpy(ptr + 1, offset, tmp - offset);
 282                 ptr += tmp - offset + 1;
 283
 284                 offset = tmp + 1;
 285         }
 286
 287         offset = (char *) domain;
 288         while (offset != NULL) {
 289                 char *tmp;
 290
 291                 tmp = strchr(offset, '.');
 292                 if (tmp == NULL) {
 293                         if (strlen(offset) == 0)
 294                                 break;
 295                         *ptr = strlen(offset);
 296                         memcpy(ptr + 1, offset, strlen(offset));
 297                         ptr += strlen(offset) + 1;
 298                         break;
 299                 }
 300
 301                 *ptr = tmp - offset;
 302                 memcpy(ptr + 1, offset, tmp - offset);
 303                 ptr += tmp - offset + 1;
 304
 305                 offset = tmp + 1;
 306         }
 307
 308         *ptr++ = 0x00;
 309
 310         return ptr - buf;
 311 }
 312
 313 static int ns_resolv(struct server_data *server, struct request_data *req,
 314                                 gpointer request, gpointer name)
 315 {
 316         GList *list;
 317         int sk, err;
 318
 319         sk = g_io_channel_unix_get_fd(server->channel);
 320
 321         err = send(sk, request, req->request_len, 0);
 322
 323         req->numserv++;
 324
 325         for (list = server->domains; list; list = list->next) {
 326                 char *domain;
 327                 unsigned char alt[1024];
 328                 struct domain_hdr *hdr = (void *) &alt;
 329                 int altlen, domlen, offset;
 330
 331                 domain = list->data;
 332
 333                 if (domain == NULL)
 334                         continue;
 335
 336                 offset = protocol_offset(server->protocol);
 337                 if (offset < 0)
 338                         return offset;
 339
 340                 domlen = strlen(domain) + 1;
 341                 if (domlen < 5)
 342                         return -EINVAL;
 343
 344                 alt[offset] = req->altid & 0xff;
 345                 alt[offset + 1] = req->altid >> 8;
 346
 347                 memcpy(alt + offset + 2, request + offset + 2, 10);
 348                 hdr->qdcount = htons(1);
 349
 350                 altlen = append_query(alt + offset + 12, sizeof(alt) - 12,
 351                                         name, domain);
 352                 if (altlen < 0)
 353                         return -EINVAL;
 354
 355                 altlen += 12;
 356
 357                 memcpy(alt + offset + altlen,
 358                         request + offset + altlen - domlen,
 359                                 req->request_len - altlen + domlen);
 360
 361                 if (server->protocol == IPPROTO_TCP) {
 362                         int req_len = req->request_len + domlen - 1;
 363
 364                         alt[0] = (req_len >> 8) & 0xff;
 365                         alt[1] = req_len & 0xff;
 366                 }
 367
 368                 err = send(sk, alt, req->request_len + domlen + 1, 0);
 369
 370                 req->numserv++;
 371         }
 372
 373         return 0;
 374 }
 375
 376 static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol)
 377 {
 378         struct domain_hdr *hdr;
 379         struct request_data *req;
 380         int dns_id, sk, err, offset = protocol_offset(protocol);
 381
 382         if (offset < 0)
 383                 return offset;
 384
 385         hdr = (void *)(reply + offset);
 386         dns_id = reply[offset] | reply[offset + 1] << 8;
 387
 388         DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id);
 389
 390         req = find_request(dns_id);
 391         if (req == NULL)
 392                 return -EINVAL;
 393
 394         DBG("id 0x%04x rcode %d", hdr->id, hdr->rcode);
 395
 396         reply[offset] = req->srcid & 0xff;
 397         reply[offset + 1] = req->srcid >> 8;
 398
 399         req->numresp++;
 400
 401         if (hdr->rcode == 0 || req->resp == NULL) {
 402                 g_free(req->resp);
 403                 req->resplen = 0;
 404
 405                 req->resp = g_try_malloc(reply_len);
 406                 if (req->resp == NULL)
 407                         return -ENOMEM;
 408
 409                 memcpy(req->resp, reply, reply_len);
 410                 req->resplen = reply_len;
 411         }
 412
 413         if (hdr->rcode > 0 && req->numresp < req->numserv)
 414                 return -EINVAL;
 415
 416         if (req->timeout > 0)
 417                 g_source_remove(req->timeout);
 418
 419         request_list = g_slist_remove(request_list, req);
 420
 421         if (protocol == IPPROTO_UDP) {
 422                 sk = g_io_channel_unix_get_fd(udp_listener_channel);
 423                 err = sendto(sk, req->resp, req->resplen, 0,
 424                              &req->sa, req->sa_len);
 425         } else {
 426                 sk = req->client_sk;
 427                 err = send(sk, req->resp, req->resplen, 0);
 428                 close(sk);
 429         }
 430
 431         g_free(req->resp);
 432         g_free(req);
 433
 434         return err;
 435 }
 436
 437 static void destroy_server(struct server_data *server)
 438 {
 439         GList *list;
 440
 441         DBG("interface %s server %s", server->interface, server->server);
 442
 443         server_list = g_slist_remove(server_list, server);
 444
 445         if (server->watch > 0)
 446                 g_source_remove(server->watch);
 447
 448         if (server->timeout > 0)
 449                 g_source_remove(server->timeout);
 450
 451         g_io_channel_unref(server->channel);
 452
 453         if (server->protocol == IPPROTO_UDP)
 454                 connman_info("Removing DNS server %s", server->server);
 455
 456         g_free(server->incoming_reply);
 457         g_free(server->server);
 458         for (list = server->domains; list; list = list->next) {
 459                 char *domain = list->data;
 460
 461                 server->domains = g_list_remove(server->domains, domain);
 462                 g_free(domain);
 463         }
 464         g_free(server->interface);
 465         g_free(server);
 466 }
 467
 468 static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition,
 469                                                         gpointer user_data)
 470 {
 471         unsigned char buf[4096];
 472         int sk, err, len;
 473
 474         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 475                 struct server_data *data = user_data;
 476
 477                 connman_error("Error with UDP server %s", data->server);
 478                 data->watch = 0;
 479                 return FALSE;
 480         }
 481
 482         sk = g_io_channel_unix_get_fd(channel);
 483
 484         len = recv(sk, buf, sizeof(buf), 0);
 485         if (len < 12)
 486                 return TRUE;
 487
 488         err = forward_dns_reply(buf, len, IPPROTO_UDP);
 489
 490         return TRUE;
 491 }
 492
 493 static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition,
 494                                                         gpointer user_data)
 495 {
 496         int sk;
 497         struct server_data *server = user_data;
 498
 499         sk = g_io_channel_unix_get_fd(channel);
 500         if (sk == 0)
 501                 return FALSE;
 502
 503         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 504                 GSList *list;
 505 hangup:
 506                 DBG("TCP server channel closed");
 507
 508                 /*
 509                  * Discard any partial response which is buffered; better
 510                  * to get a proper response from a working server.
 511                  */
 512                 g_free(server->incoming_reply);
 513                 server->incoming_reply = NULL;
 514
 515                 for (list = request_list; list; list = list->next) {
 516                         struct request_data *req = list->data;
 517                         struct domain_hdr *hdr;
 518
 519                         if (req->protocol == IPPROTO_UDP)
 520                                 continue;
 521
 522                         if (req->request == NULL)
 523                                 continue;
 524
 525                         /*
 526                          * If we're not waiting for any further response
 527                          * from another name server, then we send an error
 528                          * response to the client.
 529                          */
 530                         if (req->numserv && --(req->numserv))
 531                                 continue;
 532
 533                         hdr = (void *) (req->request + 2);
 534                         hdr->id = req->srcid;
 535                         send_response(req->client_sk, req->request,
 536                                         req->request_len, NULL, 0, IPPROTO_TCP);
 537
 538                         request_list = g_slist_remove(request_list, req);
 539                 }
 540
 541                 destroy_server(server);
 542
 543                 return FALSE;
 544         }
 545
 546         if ((condition & G_IO_OUT) && !server->connected) {
 547                 GSList *list;
 548                 GList *domains;
 549                 struct server_data *udp_server;
 550
 551                 udp_server = find_server(server->interface, server->server,
 552                                                                 IPPROTO_UDP);
 553                 if (udp_server != NULL) {
 554                         for (domains = udp_server->domains; domains;
 555                                                 domains = domains->next) {
 556                                 char *dom = domains->data;
 557
 558                                 DBG("Adding domain %s to %s",
 559                                                 dom, server->server);
 560
 561                                 server->domains = g_list_append(server->domains,
 562                                                                 g_strdup(dom));
 563                         }
 564                 }
 565
 566                 server->connected = TRUE;
 567                 server_list = g_slist_append(server_list, server);
 568
 569                 if (server->timeout > 0) {
 570                         g_source_remove(server->timeout);
 571                         server->timeout = 0;
 572                 }
 573
 574                 for (list = request_list; list; list = list->next) {
 575                         struct request_data *req = list->data;
 576
 577                         if (req->protocol == IPPROTO_UDP)
 578                                 continue;
 579
 580                         DBG("Sending req %s over TCP", (char *)req->name);
 581
 582                         if (req->timeout > 0)
 583                                 g_source_remove(req->timeout);
 584
 585                         req->timeout = g_timeout_add_seconds(30,
 586                                                 request_timeout, req);
 587                         ns_resolv(server, req, req->request, req->name);
 588                 }
 589
 590         } else if (condition & G_IO_IN) {
 591                 struct partial_reply *reply = server->incoming_reply;
 592                 int bytes_recv;
 593
 594                 if (!reply) {
 595                         unsigned char reply_len_buf[2];
 596                         uint16_t reply_len;
 597
 598                         bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK);
 599                         if (!bytes_recv) {
 600                                 goto hangup;
 601                         } else if (bytes_recv < 0) {
 602                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 603                                         return TRUE;
 604
 605                                 connman_error("DNS proxy error %s",
 606                                                 strerror(errno));
 607                                 goto hangup;
 608                         } else if (bytes_recv < 2)
 609                                 return TRUE;
 610
 611                         reply_len = reply_len_buf[1] | reply_len_buf[0] << 8;
 612                         reply_len += 2;
 613
 614                         DBG("TCP reply %d bytes", reply_len);
 615
 616                         reply = g_try_malloc(sizeof(*reply) + reply_len + 2);
 617                         if (!reply)
 618                                 return TRUE;
 619
 620                         reply->len = reply_len;
 621                         reply->received = 0;
 622
 623                         server->incoming_reply = reply;
 624                 }
 625
 626                 while (reply->received < reply->len) {
 627                         bytes_recv = recv(sk, reply->buf + reply->received,
 628                                         reply->len - reply->received, 0);
 629                         if (!bytes_recv) {
 630                                 connman_error("DNS proxy TCP disconnect");
 631                                 break;
 632                         } else if (bytes_recv < 0) {
 633                                 if (errno == EAGAIN || errno == EWOULDBLOCK)
 634                                         return TRUE;
 635
 636                                 connman_error("DNS proxy error %s",
 637                                                 strerror(errno));
 638                                 break;
 639                         }
 640                         reply->received += bytes_recv;
 641                 }
 642
 643                 forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP);
 644
 645                 g_free(reply);
 646                 server->incoming_reply = NULL;
 647
 648                 destroy_server(server);
 649
 650                 return FALSE;
 651         }
 652
 653         return TRUE;
 654 }
 655
 656 static gboolean tcp_idle_timeout(gpointer user_data)
 657 {
 658         struct server_data *server = user_data;
 659
 660         DBG("");
 661
 662         if (server == NULL)
 663                 return FALSE;
 664
 665         destroy_server(server);
 666
 667         return FALSE;
 668 }
 669
 670 static struct server_data *create_server(const char *interface,
 671                                         const char *domain, const char *server,
 672                                         int protocol)
 673 {
 674         struct addrinfo hints, *rp;
 675         struct server_data *data;
 676         int sk, ret;
 677
 678         DBG("interface %s server %s", interface, server);
 679
 680         memset(&hints, 0, sizeof(hints));
 681
 682         switch (protocol) {
 683         case IPPROTO_UDP:
 684                 hints.ai_socktype = SOCK_DGRAM;
 685                 break;
 686
 687         case IPPROTO_TCP:
 688                 hints.ai_socktype = SOCK_STREAM;
 689                 break;
 690
 691         default:
 692                 return NULL;
 693         }
 694         hints.ai_family = AF_UNSPEC;
 695         hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
 696
 697         ret = getaddrinfo(server, "53", &hints, &rp);
 698         if (ret) {
 699                 connman_error("Failed to parse server %s address: %s\n",
 700                               server, gai_strerror(ret));
 701                 return NULL;
 702         }
 703         /* Do not blindly copy this code elsewhere; it doesn't loop over the
 704            results using ->ai_next as it should. That's OK in *this* case
 705            because it was a numeric lookup; we *know* there's only one. */
 706
 707         sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 708         if (sk < 0) {
 709                 connman_error("Failed to create server %s socket", server);
 710                 freeaddrinfo(rp);
 711                 return NULL;
 712         }
 713
 714         if (interface != NULL) {
 715                 if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
 716                                 interface, strlen(interface) + 1) < 0) {
 717                         connman_error("Failed to bind server %s "
 718                                                 "to interface %s",
 719                                                         server, interface);
 720                         freeaddrinfo(rp);
 721                         close(sk);
 722                         return NULL;
 723                 }
 724         }
 725
 726         data = g_try_new0(struct server_data, 1);
 727         if (data == NULL) {
 728                 connman_error("Failed to allocate server %s data", server);
 729                 freeaddrinfo(rp);
 730                 close(sk);
 731                 return NULL;
 732         }
 733
 734         data->channel = g_io_channel_unix_new(sk);
 735         if (data->channel == NULL) {
 736                 connman_error("Failed to create server %s channel", server);
 737                 freeaddrinfo(rp);
 738                 close(sk);
 739                 g_free(data);
 740                 return NULL;
 741         }
 742
 743         g_io_channel_set_close_on_unref(data->channel, TRUE);
 744
 745         if (protocol == IPPROTO_TCP) {
 746                 g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL);
 747                 data->watch = g_io_add_watch(data->channel,
 748                         G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR,
 749                                                 tcp_server_event, data);
 750                 data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout,
 751                                                                 data);
 752         } else
 753                 data->watch = g_io_add_watch(data->channel,
 754                         G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 755                                                 udp_server_event, data);
 756
 757         data->interface = g_strdup(interface);
 758         if (domain)
 759                 data->domains = g_list_append(data->domains, g_strdup(domain));
 760         data->server = g_strdup(server);
 761         data->protocol = protocol;
 762
 763         ret = connect(sk, rp->ai_addr, rp->ai_addrlen);
 764         freeaddrinfo(rp);
 765         if (ret < 0) {
 766                 if ((protocol == IPPROTO_TCP && errno != EINPROGRESS) ||
 767                                 protocol == IPPROTO_UDP) {
 768                         GList *list;
 769
 770                         connman_error("Failed to connect to server %s", server);
 771                         if (data->watch > 0)
 772                                 g_source_remove(data->watch);
 773                         if (data->timeout > 0)
 774                                 g_source_remove(data->timeout);
 775
 776                         g_io_channel_unref(data->channel);
 777                         close(sk);
 778
 779                         g_free(data->server);
 780                         g_free(data->interface);
 781                         for (list = data->domains; list; list = list->next) {
 782                                 char *domain = list->data;
 783
 784                                 data->domains = g_list_remove(data->domains,
 785                                                                         domain);
 786                                 g_free(domain);
 787                         }
 788                         g_free(data);
 789                         return NULL;
 790                 }
 791         }
 792
 793         if (protocol == IPPROTO_UDP) {
 794                 /* Enable new servers by default */
 795                 data->enabled = TRUE;
 796                 connman_info("Adding DNS server %s", data->server);
 797
 798                 server_list = g_slist_append(server_list, data);
 799
 800                 return data;
 801         }
 802
 803         return NULL;
 804 }
 805
 806 static gboolean resolv(struct request_data *req,
 807                                 gpointer request, gpointer name)
 808 {
 809         GSList *list;
 810
 811         for (list = server_list; list; list = list->next) {
 812                 struct server_data *data = list->data;
 813
 814                 DBG("server %s enabled %d", data->server, data->enabled);
 815
 816                 if (data->enabled == FALSE)
 817                         continue;
 818
 819                 if (data->watch == 0 && data->protocol == IPPROTO_UDP)
 820                         data->watch = g_io_add_watch(data->channel,
 821                                 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
 822                                                 udp_server_event, data);
 823
 824                 if (ns_resolv(data, req, request, name) < 0)
 825                         continue;
 826         }
 827
 828         return TRUE;
 829 }
 830
 831 static void append_domain(const char *interface, const char *domain)
 832 {
 833         GSList *list;
 834
 835         DBG("interface %s domain %s", interface, domain);
 836
 837         for (list = server_list; list; list = list->next) {
 838                 struct server_data *data = list->data;
 839                 GList *dom_list;
 840                 char *dom;
 841                 gboolean dom_found = FALSE;
 842
 843                 if (data->interface == NULL)
 844                         continue;
 845
 846                 if (g_str_equal(data->interface, interface) == FALSE)
 847                         continue;
 848
 849                 for (dom_list = data->domains; dom_list;
 850                                 dom_list = dom_list->next) {
 851                         dom = dom_list->data;
 852
 853                         if (g_str_equal(dom, domain)) {
 854                                 dom_found = TRUE;
 855                                 break;
 856                         }
 857                 }
 858
 859                 if (dom_found == FALSE) {
 860                         data->domains =
 861                                 g_list_append(data->domains, g_strdup(domain));
 862                 }
 863         }
 864 }
 865
 866 static int dnsproxy_append(const char *interface, const char *domain,
 867                                                         const char *server)
 868 {
 869         struct server_data *data;
 870
 871         DBG("interface %s server %s", interface, server);
 872
 873         if (server == NULL && domain == NULL)
 874                 return -EINVAL;
 875
 876         if (server == NULL) {
 877                 append_domain(interface, domain);
 878
 879                 return 0;
 880         }
 881
 882         if (g_str_equal(server, "127.0.0.1") == TRUE)
 883                 return -ENODEV;
 884
 885         data = find_server(interface, server, IPPROTO_UDP);
 886         if (data != NULL) {
 887                 append_domain(interface, domain);
 888                 return 0;
 889         }
 890
 891         data = create_server(interface, domain, server, IPPROTO_UDP);
 892         if (data == NULL)
 893                 return -EIO;
 894
 895         return 0;
 896 }
 897
 898 static void remove_server(const char *interface, const char *domain,
 899                         const char *server, int protocol)
 900 {
 901         struct server_data *data;
 902
 903         data = find_server(interface, server, protocol);
 904         if (data == NULL)
 905                 return;
 906
 907         destroy_server(data);
 908 }
 909
 910 static int dnsproxy_remove(const char *interface, const char *domain,
 911                                                         const char *server)
 912 {
 913         DBG("interface %s server %s", interface, server);
 914
 915         if (server == NULL)
 916                 return -EINVAL;
 917
 918         if (g_str_equal(server, "127.0.0.1") == TRUE)
 919                 return -ENODEV;
 920
 921         remove_server(interface, domain, server, IPPROTO_UDP);
 922         remove_server(interface, domain, server, IPPROTO_TCP);
 923
 924         return 0;
 925 }
 926
 927 static void dnsproxy_flush(void)
 928 {
 929         GSList *list;
 930
 931         list = request_pending_list;
 932         while (list) {
 933                 struct request_data *req = list->data;
 934
 935                 list = list->next;
 936
 937                 request_pending_list =
 938                                 g_slist_remove(request_pending_list, req);
 939                 resolv(req, req->request, req->name);
 940                 g_free(req->request);
 941                 g_free(req->name);
 942         }
 943 }
 944
 945 static struct connman_resolver dnsproxy_resolver = {
 946         .name           = "dnsproxy",
 947         .priority       = CONNMAN_RESOLVER_PRIORITY_HIGH,
 948         .append         = dnsproxy_append,
 949         .remove         = dnsproxy_remove,
 950         .flush          = dnsproxy_flush,
 951 };
 952
 953 static void dnsproxy_offline_mode(connman_bool_t enabled)
 954 {
 955         GSList *list;
 956
 957         DBG("enabled %d", enabled);
 958
 959         for (list = server_list; list; list = list->next) {
 960                 struct server_data *data = list->data;
 961
 962                 if (enabled == FALSE) {
 963                         connman_info("Enabling DNS server %s", data->server);
 964                         data->enabled = TRUE;
 965                 } else {
 966                         connman_info("Disabling DNS server %s", data->server);
 967                         data->enabled = FALSE;
 968                 }
 969         }
 970 }
 971
 972 static void dnsproxy_default_changed(struct connman_service *service)
 973 {
 974         GSList *list;
 975         char *interface;
 976
 977         DBG("service %p", service);
 978
 979         if (service == NULL) {
 980                 /* When no services are active, then disable DNS proxying */
 981                 dnsproxy_offline_mode(TRUE);
 982                 return;
 983         }
 984
 985         interface = connman_service_get_interface(service);
 986         if (interface == NULL)
 987                 return;
 988
 989         for (list = server_list; list; list = list->next) {
 990                 struct server_data *data = list->data;
 991
 992                 if (g_strcmp0(data->interface, interface) == 0) {
 993                         connman_info("Enabling DNS server %s", data->server);
 994                         data->enabled = TRUE;
 995                 } else {
 996                         connman_info("Disabling DNS server %s", data->server);
 997                         data->enabled = FALSE;
 998                 }
 999         }
1000
1001         g_free(interface);
1002 }
1003
1004 static struct connman_notifier dnsproxy_notifier = {
1005         .name                   = "dnsproxy",
1006         .default_changed        = dnsproxy_default_changed,
1007         .offline_mode           = dnsproxy_offline_mode,
1008 };
1009
1010 static unsigned char opt_edns0_type[2] = { 0x00, 0x29 };
1011
1012 static int parse_request(unsigned char *buf, int len,
1013                                         char *name, unsigned int size)
1014 {
1015         struct domain_hdr *hdr = (void *) buf;
1016         uint16_t qdcount = ntohs(hdr->qdcount);
1017         uint16_t arcount = ntohs(hdr->arcount);
1018         unsigned char *ptr;
1019         char *last_label = NULL;
1020         unsigned int remain, used = 0;
1021
1022         if (len < 12)
1023                 return -EINVAL;
1024
1025         DBG("id 0x%04x qr %d opcode %d qdcount %d arcount %d",
1026                                         hdr->id, hdr->qr, hdr->opcode,
1027                                                         qdcount, arcount);
1028
1029         if (hdr->qr != 0 || qdcount != 1)
1030                 return -EINVAL;
1031
1032         memset(name, 0, size);
1033
1034         ptr = buf + sizeof(struct domain_hdr);
1035         remain = len - sizeof(struct domain_hdr);
1036
1037         while (remain > 0) {
1038                 uint8_t len = *ptr;
1039
1040                 if (len == 0x00) {
1041                         last_label = (char *) (ptr + 1);
1042                         break;
1043                 }
1044
1045                 if (used + len + 1 > size)
1046                         return -ENOBUFS;
1047
1048                 strncat(name, (char *) (ptr + 1), len);
1049                 strcat(name, ".");
1050
1051                 used += len + 1;
1052
1053                 ptr += len + 1;
1054                 remain -= len + 1;
1055         }
1056
1057         if (last_label && arcount && remain >= 9 && last_label[4] == 0 &&
1058                                 !memcmp(last_label + 5, opt_edns0_type, 2)) {
1059                 uint16_t edns0_bufsize;
1060
1061                 edns0_bufsize = last_label[7] << 8 | last_label[8];
1062
1063                 DBG("EDNS0 buffer size %u", edns0_bufsize);
1064
1065                 /* This is an evil hack until full TCP support has been
1066                  * implemented.
1067                  *
1068                  * Somtimes the EDNS0 request gets send with a too-small
1069                  * buffer size. Since glibc doesn't seem to crash when it
1070                  * gets a response biffer then it requested, just bump
1071                  * the buffer size up to 4KiB.
1072                  */
1073                 if (edns0_bufsize < 0x1000) {
1074                         last_label[7] = 0x10;
1075                         last_label[8] = 0x00;
1076                 }
1077         }
1078
1079         DBG("query %s", name);
1080
1081         return 0;
1082 }
1083
1084 static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition,
1085                                                         gpointer user_data)
1086 {
1087         unsigned char buf[768];
1088         char query[512];
1089         struct request_data *req;
1090         struct server_data *server;
1091         int sk, client_sk, len, err;
1092         struct sockaddr_in6 client_addr;
1093         socklen_t client_addr_len = sizeof(client_addr);
1094         GSList *list;
1095
1096         DBG("condition 0x%x", condition);
1097
1098         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1099                 if (tcp_listener_watch > 0)
1100                         g_source_remove(tcp_listener_watch);
1101                 tcp_listener_watch = 0;
1102
1103                 connman_error("Error with TCP listener channel");
1104
1105                 return FALSE;
1106         }
1107
1108         sk = g_io_channel_unix_get_fd(channel);
1109
1110         client_sk = accept(sk, (void *)&client_addr, &client_addr_len);
1111         if (client_sk < 0) {
1112                 connman_error("Accept failure on TCP listener");
1113                 tcp_listener_watch = 0;
1114                 return FALSE;
1115         }
1116
1117         len = recv(client_sk, buf, sizeof(buf), 0);
1118         if (len < 2)
1119                 return TRUE;
1120
1121         DBG("Received %d bytes (id 0x%04x)", len, buf[2] | buf[3] << 8);
1122
1123         err = parse_request(buf + 2, len - 2, query, sizeof(query));
1124         if (err < 0 || (g_slist_length(server_list) == 0 &&
1125                                 connman_ondemand_connected())) {
1126                 send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP);
1127                 return TRUE;
1128         }
1129
1130         req = g_try_new0(struct request_data, 1);
1131         if (req == NULL)
1132                 return TRUE;
1133
1134         memcpy(&req->sa, &client_addr, client_addr_len);
1135         req->sa_len = client_addr_len;
1136         req->client_sk = client_sk;
1137         req->protocol = IPPROTO_TCP;
1138
1139         request_id += 2;
1140         if (request_id == 0x0000 || request_id == 0xffff)
1141                 request_id += 2;
1142
1143         req->srcid = buf[2] | (buf[3] << 8);
1144         req->dstid = request_id;
1145         req->altid = request_id + 1;
1146         req->request_len = len;
1147
1148         buf[2] = req->dstid & 0xff;
1149         buf[3] = req->dstid >> 8;
1150
1151         req->numserv = 0;
1152         request_list = g_slist_append(request_list, req);
1153
1154         for (list = server_list; list; list = list->next) {
1155                 struct server_data *data = list->data;
1156                 GList *domains;
1157
1158                 if (data->protocol != IPPROTO_UDP || data->enabled == FALSE)
1159                         continue;
1160
1161                 server = create_server(data->interface, NULL,
1162                                         data->server, IPPROTO_TCP);
1163
1164                 /*
1165                  * If server is NULL, we're not connected yet.
1166                  * Copy the relevant buffers and continue with
1167                  * the next nameserver.
1168                  * The request will actually be sent once we're
1169                  * properly connected over TCP to this nameserver.
1170                  */
1171                 if (server == NULL) {
1172                         req->request = g_try_malloc0(req->request_len);
1173                         if (req->request == NULL)
1174                                 return TRUE;
1175
1176                         memcpy(req->request, buf, req->request_len);
1177
1178                         req->name = g_try_malloc0(sizeof(query));
1179                         if (req->name == NULL) {
1180                                 g_free(req->request);
1181                                 return TRUE;
1182                         }
1183                         memcpy(req->name, query, sizeof(query));
1184
1185                         continue;
1186                 }
1187
1188                 if (req->timeout > 0)
1189                         g_source_remove(req->timeout);
1190
1191                 for (domains = data->domains; domains;
1192                                 domains = domains->next) {
1193                         char *dom = domains->data;
1194
1195                         DBG("Adding domain %s to %s", dom, server->server);
1196
1197                         server->domains = g_list_append(server->domains,
1198                                                 g_strdup(dom));
1199                 }
1200
1201                 req->timeout = g_timeout_add_seconds(30, request_timeout, req);
1202                 ns_resolv(server, req, buf, query);
1203         }
1204
1205         return TRUE;
1206 }
1207
1208 static gboolean udp_listener_event(GIOChannel *channel, GIOCondition condition,
1209                                                         gpointer user_data)
1210 {
1211         unsigned char buf[768];
1212         char query[512];
1213         struct request_data *req;
1214         struct sockaddr_in6 client_addr;
1215         socklen_t client_addr_len = sizeof(client_addr);
1216         int sk, err, len;
1217
1218         if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
1219                 connman_error("Error with UDP listener channel");
1220                 udp_listener_watch = 0;
1221                 return FALSE;
1222         }
1223
1224         sk = g_io_channel_unix_get_fd(channel);
1225
1226         memset(&client_addr, 0, client_addr_len);
1227         len = recvfrom(sk, buf, sizeof(buf), 0, (void *)&client_addr,
1228                        &client_addr_len);
1229         if (len < 2)
1230                 return TRUE;
1231
1232         DBG("Received %d bytes (id 0x%04x)", len, buf[0] | buf[1] << 8);
1233
1234         err = parse_request(buf, len, query, sizeof(query));
1235         if (err < 0 || (g_slist_length(server_list) == 0 &&
1236                                 connman_ondemand_connected())) {
1237                 send_response(sk, buf, len, (void *)&client_addr,
1238                               client_addr_len, IPPROTO_UDP);
1239                 return TRUE;
1240         }
1241
1242         req = g_try_new0(struct request_data, 1);
1243         if (req == NULL)
1244                 return TRUE;
1245
1246         memcpy(&req->sa, &client_addr, client_addr_len);
1247         req->sa_len = client_addr_len;
1248         req->client_sk = 0;
1249         req->protocol = IPPROTO_UDP;
1250
1251         request_id += 2;
1252         if (request_id == 0x0000 || request_id == 0xffff)
1253                 request_id += 2;
1254
1255         req->srcid = buf[0] | (buf[1] << 8);
1256         req->dstid = request_id;
1257         req->altid = request_id + 1;
1258         req->request_len = len;
1259
1260         buf[0] = req->dstid & 0xff;
1261         buf[1] = req->dstid >> 8;
1262
1263         if (!connman_ondemand_connected()) {
1264                 DBG("Starting on demand connection");
1265                 /*
1266                  * We're not connected, let's queue the request and start
1267                  * an on-demand connection.
1268                  */
1269                 req->request = g_try_malloc0(req->request_len);
1270                 if (req->request == NULL)
1271                         return TRUE;
1272
1273                 memcpy(req->request, buf, req->request_len);
1274
1275                 req->name = g_try_malloc0(sizeof(query));
1276                 if (req->name == NULL) {
1277                         g_free(req->request);
1278                         return TRUE;
1279                 }
1280                 memcpy(req->name, query, sizeof(query));
1281
1282                 request_pending_list = g_slist_append(request_pending_list,
1283                                                                         req);
1284
1285                 connman_ondemand_start("", 300);
1286
1287                 return TRUE;
1288         }
1289
1290
1291         req->numserv = 0;
1292         req->timeout = g_timeout_add_seconds(5, request_timeout, req);
1293         request_list = g_slist_append(request_list, req);
1294
1295         return resolv(req, buf, query);
1296 }
1297
1298 static int create_dns_listener(int protocol)
1299 {
1300         GIOChannel *channel;
1301         const char *ifname = "lo", *proto;
1302         union {
1303                 struct sockaddr sa;
1304                 struct sockaddr_in6 sin6;
1305                 struct sockaddr_in sin;
1306         } s;
1307         socklen_t slen;
1308         int sk, type, v6only = 0;
1309         int family = AF_INET6;
1310
1311         DBG("");
1312
1313         switch (protocol) {
1314         case IPPROTO_UDP:
1315                 proto = "UDP";
1316                 type = SOCK_DGRAM;
1317                 break;
1318
1319         case IPPROTO_TCP:
1320                 proto = "TCP";
1321                 type = SOCK_STREAM;
1322                 break;
1323
1324         default:
1325                 return -EINVAL;
1326         }
1327
1328         sk = socket(family, type, protocol);
1329         if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
1330                 connman_error("No IPv6 support; DNS proxy listening only on Legacy IP");
1331                 family = AF_INET;
1332                 sk = socket(family, type, protocol);
1333         }
1334         if (sk < 0) {
1335                 connman_error("Failed to create %s listener socket", proto);
1336                 return -EIO;
1337         }
1338
1339         if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE,
1340                                         ifname, strlen(ifname) + 1) < 0) {
1341                 connman_error("Failed to bind %s listener interface", proto);
1342                 close(sk);
1343                 return -EIO;
1344         }
1345         /* Ensure it accepts Legacy IP connections too */
1346         if (family == AF_INET6 &&
1347                         setsockopt(sk, SOL_IPV6, IPV6_V6ONLY,
1348                                         &v6only, sizeof(v6only)) < 0) {
1349                 connman_error("Failed to clear V6ONLY on %s listener socket",
1350                               proto);
1351                 close(sk);
1352                 return -EIO;
1353         }
1354
1355         if (family == AF_INET) {
1356                 memset(&s.sin, 0, sizeof(s.sin));
1357                 s.sin.sin_family = AF_INET;
1358                 s.sin.sin_port = htons(53);
1359                 s.sin.sin_addr.s_addr = htonl(INADDR_ANY);
1360                 slen = sizeof(s.sin);
1361         } else {
1362                 memset(&s.sin6, 0, sizeof(s.sin6));
1363                 s.sin6.sin6_family = AF_INET6;
1364                 s.sin6.sin6_port = htons(53);
1365                 s.sin6.sin6_addr = in6addr_any;
1366                 slen = sizeof(s.sin6);
1367         }
1368
1369         if (bind(sk, &s.sa, slen) < 0) {
1370                 connman_error("Failed to bind %s listener socket", proto);
1371                 close(sk);
1372                 return -EIO;
1373         }
1374
1375         if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) {
1376                 connman_error("Failed to listen on TCP socket");
1377                 close(sk);
1378                 return -EIO;
1379         }
1380
1381         channel = g_io_channel_unix_new(sk);
1382         if (channel == NULL) {
1383                 connman_error("Failed to create %s listener channel", proto);
1384                 close(sk);
1385                 return -EIO;
1386         }
1387
1388         g_io_channel_set_close_on_unref(channel, TRUE);
1389
1390         if (protocol == IPPROTO_TCP) {
1391                 tcp_listener_channel = channel;
1392                 tcp_listener_watch = g_io_add_watch(channel,
1393                                         G_IO_IN, tcp_listener_event, NULL);
1394         } else {
1395                 udp_listener_channel = channel;
1396                 udp_listener_watch = g_io_add_watch(channel,
1397                                         G_IO_IN, udp_listener_event, NULL);
1398         }
1399
1400         return 0;
1401 }
1402
1403 static void destroy_udp_listener(void)
1404 {
1405         DBG("");
1406
1407         if (udp_listener_watch > 0)
1408                 g_source_remove(udp_listener_watch);
1409
1410         g_io_channel_unref(udp_listener_channel);
1411 }
1412
1413 static void destroy_tcp_listener(void)
1414 {
1415         DBG("");
1416
1417         if (tcp_listener_watch > 0)
1418                 g_source_remove(tcp_listener_watch);
1419
1420         g_io_channel_unref(tcp_listener_channel);
1421 }
1422
1423 static int create_listener(void)
1424 {
1425         int err;
1426
1427         err = create_dns_listener(IPPROTO_UDP);
1428         if (err < 0)
1429                 return err;
1430
1431         err = create_dns_listener(IPPROTO_TCP);
1432         if (err < 0) {
1433                 destroy_udp_listener();
1434                 return err;
1435         }
1436
1437         connman_resolver_append("lo", NULL, "127.0.0.1");
1438
1439         return 0;
1440 }
1441
1442 static void destroy_listener(void)
1443 {
1444         GSList *list;
1445
1446         connman_resolver_remove_all("lo");
1447
1448         for (list = request_pending_list; list; list = list->next) {
1449                 struct request_data *req = list->data;
1450
1451                 DBG("Dropping pending request (id 0x%04x -> 0x%04x)",
1452                                                 req->srcid, req->dstid);
1453
1454                 g_free(req->resp);
1455                 g_free(req->request);
1456                 g_free(req->name);
1457                 g_free(req);
1458                 list->data = NULL;
1459         }
1460
1461         g_slist_free(request_pending_list);
1462         request_pending_list = NULL;
1463
1464         for (list = request_list; list; list = list->next) {
1465                 struct request_data *req = list->data;
1466
1467                 DBG("Dropping request (id 0x%04x -> 0x%04x)",
1468                                                 req->srcid, req->dstid);
1469
1470                 g_free(req->resp);
1471                 g_free(req->request);
1472                 g_free(req->name);
1473                 g_free(req);
1474                 list->data = NULL;
1475         }
1476
1477         g_slist_free(request_list);
1478         request_list = NULL;
1479
1480         destroy_tcp_listener();
1481         destroy_udp_listener();
1482 }
1483
1484 int __connman_dnsproxy_init(connman_bool_t dnsproxy)
1485 {
1486         int err;
1487
1488         dnsproxy_enabled = dnsproxy;
1489         if (dnsproxy_enabled == FALSE)
1490                 return 0;
1491
1492         err = create_listener();
1493         if (err < 0)
1494                 return err;
1495
1496         err = connman_resolver_register(&dnsproxy_resolver);
1497         if (err < 0)
1498                 goto destroy;
1499
1500         err = connman_notifier_register(&dnsproxy_notifier);
1501         if (err < 0)
1502                 goto unregister;
1503
1504         return 0;
1505
1506 unregister:
1507         connman_resolver_unregister(&dnsproxy_resolver);
1508
1509 destroy:
1510         destroy_listener();
1511
1512         return err;
1513 }
1514
1515 void __connman_dnsproxy_cleanup(void)
1516 {
1517         if (dnsproxy_enabled == FALSE)
1518                 return;
1519
1520         connman_notifier_unregister(&dnsproxy_notifier);
1521
1522         connman_resolver_unregister(&dnsproxy_resolver);
1523
1524         destroy_listener();
1525 }