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