src/protocol/bittorrent/common.c

   1 /* Library of common BitTorrent code */
   2
   3 #ifdef HAVE_CONFIG_H
   4 #include "config.h"
   5 #endif
   6
   7 #include <stdlib.h>
   8 #include <string.h>
   9
  10 #include "elinks.h"
  11
  12 #include "main/select.h"
  13 #include "network/connection.h"
  14 #include "protocol/bittorrent/common.h"
  15 #include "session/download.h"
  16 #include "util/conv.h"
  17 #include "util/error.h"
  18 #include "util/lists.h"
  19 #include "util/memory.h"
  20 #include "util/random.h"
  21 #include "util/sha1.h"
  22 #include "util/string.h"
  23 #include "util/snprintf.h"
  24
  25 const bittorrent_id_T BITTORRENT_NULL_ID;
  26
  27 /* Debug function which returns printable peer ID. */
  28 unsigned char *
  29 get_peer_id(bittorrent_id_T peer_id)
  30 {
  31         static unsigned char hex[41];
  32         int i, j;
  33
  34         if (bittorrent_id_is_empty(peer_id)) {
  35                 snprintf(hex, sizeof(hex), "unknown id %p", peer_id);
  36                 return hex;
  37         }
  38
  39         for (i = 0, j = 0; i < sizeof(bittorrent_id_T); i++, j++) {
  40                 unsigned char value = peer_id[i];
  41
  42                 if (isprint(value)) {
  43                         hex[j] = value;
  44                 } else {
  45                         hex[j++]   = hx(value >> 4 & 0xF);
  46                         hex[j] = hx(value & 0xF);
  47                 }
  48         }
  49
  50         hex[j] = 0;
  51
  52         return hex;
  53 }
  54
  55 unsigned char *
  56 get_peer_message(enum bittorrent_message_id message_id)
  57 {
  58         static struct {
  59                 enum bittorrent_message_id message_id;
  60                 unsigned char *name;
  61         } messages[] = {
  62                 { BITTORRENT_MESSAGE_INCOMPLETE,        "incomplete"     },
  63                 { BITTORRENT_MESSAGE_KEEP_ALIVE,        "keep-alive"     },
  64                 { BITTORRENT_MESSAGE_CHOKE,             "choke"          },
  65                 { BITTORRENT_MESSAGE_UNCHOKE,           "unchoke"        },
  66                 { BITTORRENT_MESSAGE_INTERESTED,        "interested"     },
  67                 { BITTORRENT_MESSAGE_NOT_INTERESTED,    "not-interested" },
  68                 { BITTORRENT_MESSAGE_HAVE,              "have"           },
  69                 { BITTORRENT_MESSAGE_BITFIELD,          "bitfield"       },
  70                 { BITTORRENT_MESSAGE_REQUEST,           "request"        },
  71                 { BITTORRENT_MESSAGE_PIECE,             "piece"          },
  72                 { BITTORRENT_MESSAGE_CANCEL,            "cancel"         },
  73
  74                 { 0, NULL },
  75         };
  76         int i;
  77
  78         for (i = 0; messages[i].name; i++)
  79                 if (messages[i].message_id == message_id)
  80                         return messages[i].name;
  81
  82         return "unknown";
  83 }
  84
  85
  86 unsigned char *
  87 get_hexed_bittorrent_id(bittorrent_id_T id)
  88 {
  89         static unsigned char hex[SHA_DIGEST_LENGTH * 2 + 1];
  90         int i;
  91
  92         for (i = 0; i < sizeof(bittorrent_id_T); i++) {
  93                 int j = i * 2;
  94
  95                 hex[j++] = hx(id[i] >> 4 & 0xF);
  96                 hex[j]   = hx(id[i] & 0xF);
  97         }
  98
  99         hex[SHA_DIGEST_LENGTH * 2] = 0;
 100
 101         return hex;
 102 }
 103
 104 int
 105 bittorrent_piece_is_valid(struct bittorrent_meta *meta,
 106                           uint32_t piece, unsigned char *data, uint32_t datalen)
 107 {
 108         unsigned char *piece_hash;
 109         bittorrent_id_T data_hash;
 110
 111         assert(piece < meta->pieces);
 112
 113         SHA1(data, datalen, data_hash);
 114         piece_hash = &meta->piece_hash[piece * SHA_DIGEST_LENGTH];
 115
 116         return !memcmp(data_hash, piece_hash, SHA_DIGEST_LENGTH);
 117 }
 118
 119 void
 120 done_bittorrent_meta(struct bittorrent_meta *meta)
 121 {
 122         free_uri_list(&meta->tracker_uris);
 123         mem_free_if(meta->name);
 124         mem_free_if(meta->comment);
 125         mem_free_if(meta->piece_hash);
 126         free_list(meta->files);
 127 }
 128
 129 void
 130 done_bittorrent_message(struct bittorrent_message *message)
 131 {
 132         del_from_list(message);
 133         done_uri(message->uri);
 134         mem_free(message);
 135 }
 136
 137
 138 /* ************************************************************************** */
 139 /* Peer information management: */
 140 /* ************************************************************************** */
 141
 142 /* Generate a peer ID with of the form: 'E' <version> '-' <random> */
 143 void
 144 init_bittorrent_peer_id(bittorrent_id_T peer_id)
 145 {
 146         unsigned char *version = VERSION;
 147         int dots = 0;
 148         int i = 0;
 149
 150         srand(time(NULL));
 151
 152         peer_id[i++] = 'E';
 153         peer_id[i++] = 'L';
 154
 155         for (; *version && i < sizeof(bittorrent_id_T); version++) {
 156                 if (isdigit(*version)) {
 157                         peer_id[i++] = *version;
 158
 159                 } else if (*version == '.' && !dots) {
 160                         dots = 1;
 161
 162                 } else {
 163                         peer_id[i++] = '-';
 164                         break;
 165                 }
 166
 167                 peer_id[i++] = *version;
 168         }
 169
 170         /* Hmm, sizeof(peer_id) don't work here. */
 171         random_nonce(peer_id + i, sizeof(bittorrent_id_T) - i);
 172         while (i < sizeof(bittorrent_id_T)) {
 173                 peer_id[i] = hx(peer_id[i] & 0xF);
 174                 i++;
 175         }
 176 }
 177
 178 int
 179 bittorrent_id_is_known(struct bittorrent_connection *bittorrent,
 180                        bittorrent_id_T id)
 181 {
 182         struct bittorrent_peer_connection *peer;
 183
 184         /* The peer ID matches the client ID? */
 185         if (!memcmp(bittorrent->peer_id, id, sizeof(bittorrent->peer_id)))
 186                 return 1;
 187
 188         foreach (peer, bittorrent->peers)
 189                 if (!memcmp(peer->id, id, sizeof(peer->id)))
 190                         return 1;
 191
 192         if (get_peer_from_bittorrent_pool(bittorrent, id))
 193                 return 1;
 194
 195         return 0;
 196 }
 197
 198 struct bittorrent_peer *
 199 get_peer_from_bittorrent_pool(struct bittorrent_connection *bittorrent,
 200                               bittorrent_id_T id)
 201 {
 202         struct bittorrent_peer *peer_info;
 203
 204         foreach (peer_info, bittorrent->peer_pool)
 205                 if (!memcmp(peer_info->id, id, sizeof(peer_info->id)))
 206                         return peer_info;
 207
 208         return NULL;
 209 }
 210
 211 enum bittorrent_state
 212 add_peer_to_bittorrent_pool(struct bittorrent_connection *bittorrent,
 213                             bittorrent_id_T id, int port,
 214                             const unsigned char *ip, int iplen)
 215 {
 216         struct bittorrent_peer *peer;
 217
 218         /* Check sanity. Don't error out here since entries in the tracker
 219          * responses can contain garbage and we don't want to bring down the
 220          * whole connection for that. */
 221         if (iplen <= 0 || !uri_port_is_valid(port))
 222                 return BITTORRENT_STATE_OK;
 223
 224         /* The ID can be NULL for the compact format. */
 225         if (id) {
 226                 enum bittorrent_blacklist_flags flags;
 227
 228                 if (bittorrent_id_is_empty(id))
 229                         return BITTORRENT_STATE_ERROR;
 230
 231                 /* Check if the peer is already known. */
 232                 if (bittorrent_id_is_known(bittorrent, id))
 233                         return BITTORRENT_STATE_OK;
 234
 235                 flags = get_bittorrent_blacklist_flags(id);
 236                 if (flags != BITTORRENT_BLACKLIST_NONE)
 237                         return BITTORRENT_STATE_OK;
 238         }
 239
 240         /* Really add the peer. */
 241
 242         peer = mem_calloc(1, sizeof(*peer) + iplen);
 243         if (!peer) return BITTORRENT_STATE_OUT_OF_MEM;
 244
 245         peer->port = port;
 246         if (iplen) memcpy(peer->ip, ip, iplen);
 247         if (id) memcpy(peer->id, id, sizeof(peer->id));
 248
 249         add_to_list(bittorrent->peer_pool, peer);
 250
 251         return BITTORRENT_STATE_OK;
 252 }
 253
 254
 255 /* ************************************************************************** */
 256 /* Peer request management: */
 257 /* ************************************************************************** */
 258
 259 struct bittorrent_peer_request *
 260 get_bittorrent_peer_request(struct bittorrent_peer_status *status,
 261                             uint32_t piece, uint32_t offset, uint32_t length)
 262 {
 263         struct bittorrent_peer_request *request;
 264
 265         foreach (request, status->requests)  {
 266                 if (request->piece == piece
 267                     && request->offset == offset
 268                     && request->length == length)
 269                         return request;
 270         }
 271
 272         return NULL;
 273 }
 274
 275 void
 276 add_bittorrent_peer_request(struct bittorrent_peer_status *status,
 277                             uint32_t piece, uint32_t offset, uint32_t length)
 278 {
 279         struct bittorrent_peer_request *request;
 280
 281         request = get_bittorrent_peer_request(status, piece, offset, length);
 282         if (request) return;
 283
 284         request = mem_alloc(sizeof(*request));
 285         if (!request) return;
 286
 287         request->piece  = piece;
 288         request->offset = offset;
 289         request->length = length;
 290
 291         /* FIXME: Rather insert the request so that we atleast try to get
 292          * some sort of sequential access to piece data. */
 293         add_to_list_end(status->requests, request);
 294 }
 295
 296 void
 297 del_bittorrent_peer_request(struct bittorrent_peer_status *status,
 298                             uint32_t piece, uint32_t offset, uint32_t length)
 299 {
 300         struct bittorrent_peer_request *request;
 301
 302         request = get_bittorrent_peer_request(status, piece, offset, length);
 303         if (!request) return;
 304
 305         del_from_list(request);
 306         mem_free(request);
 307 }
 308
 309
 310 /* ************************************************************************** */
 311 /* Generic URI downloader: */
 312 /* ************************************************************************** */
 313
 314 struct bittorrent_fetcher {
 315         struct bittorrent_fetcher **ref;
 316         bittorrent_fetch_callback_T callback;
 317         void *data;
 318         int redirects;
 319         unsigned int delete:1;
 320         struct download download;
 321 };
 322
 323 /* This part of the code is very lowlevel and ELinks specific. The download
 324  * callback is called each time there is some progress, such as new data. So
 325  * first it basically checks the state and tries to handle it accordingly.
 326  * Redirects are also handled here. */
 327 static void
 328 bittorrent_fetch_callback(struct download *download, void *data)
 329 {
 330         struct bittorrent_fetcher *fetcher = data;
 331         struct fragment *fragment;
 332         struct bittorrent_const_string response;
 333         struct cache_entry *cached = download->cached;
 334
 335         /* If the callback was removed we should shutdown ASAP. */
 336         if (!fetcher->callback || is_in_state(download->state, S_INTERRUPTED)) {
 337                 if (is_in_state(download->state, S_INTERRUPTED))
 338                         mem_free(fetcher);
 339                 return;
 340         }
 341
 342         if (is_in_result_state(download->state)
 343             && !is_in_state(download->state, S_OK)) {
 344                 fetcher->callback(fetcher->data, download->state, NULL);
 345                 if (fetcher->ref)
 346                         *fetcher->ref = NULL;
 347                 mem_free(fetcher);
 348                 return;
 349         }
 350
 351         if (!cached || is_in_queued_state(download->state))
 352                 return;
 353
 354         if (cached->redirect && fetcher->redirects++ < MAX_REDIRECTS) {
 355                 cancel_download(download, 0);
 356
 357                 download->state = connection_state(S_WAIT_REDIR);
 358
 359                 load_uri(cached->redirect, cached->uri, download,
 360                          PRI_DOWNLOAD, CACHE_MODE_NORMAL,
 361                          download->progress ? download->progress->start : 0);
 362
 363                 return;
 364         }
 365
 366         if (is_in_progress_state(download->state))
 367                 return;
 368
 369         assert(is_in_state(download->state, S_OK));
 370
 371         /* If the entry is chunked defragment it and grab the single, remaining
 372          * fragment. */
 373         fragment = get_cache_fragment(cached);
 374         if (!fragment) {
 375                 fetcher->callback(fetcher->data, connection_state(S_OUT_OF_MEM), NULL);
 376                 if (fetcher->ref)
 377                         *fetcher->ref = NULL;
 378                 mem_free(fetcher);
 379                 return;
 380         }
 381
 382         response.source = fragment->data;
 383         response.length = fragment->length;
 384
 385         fetcher->callback(fetcher->data, connection_state(S_OK), &response);
 386
 387         if (fetcher->delete)
 388                 delete_cache_entry(cached);
 389         if (fetcher->ref)
 390                 *fetcher->ref = NULL;
 391         mem_free(fetcher);
 392 }
 393
 394 struct bittorrent_fetcher *
 395 init_bittorrent_fetch(struct bittorrent_fetcher **fetcher_ref,
 396                       struct uri *uri, bittorrent_fetch_callback_T callback,
 397                       void *data, int delete)
 398 {
 399         struct bittorrent_fetcher *fetcher;
 400
 401         fetcher = mem_calloc(1, sizeof(*fetcher));
 402         if (!fetcher) {
 403                 callback(data, connection_state(S_OUT_OF_MEM), NULL);
 404                 return NULL;
 405         }
 406
 407         if (fetcher_ref)
 408                 *fetcher_ref = fetcher;
 409
 410         fetcher->ref               = fetcher_ref;
 411         fetcher->callback          = callback;
 412         fetcher->data              = data;
 413         fetcher->delete            = delete;
 414         fetcher->download.callback = bittorrent_fetch_callback;
 415         fetcher->download.data     = fetcher;
 416
 417         load_uri(uri, NULL, &fetcher->download, PRI_MAIN, CACHE_MODE_NORMAL, -1);
 418
 419         return fetcher;
 420 }
 421
 422 static void
 423 end_bittorrent_fetch(void *fetcher_data)
 424 {
 425         struct bittorrent_fetcher *fetcher = fetcher_data;
 426
 427         assert(fetcher && !fetcher->callback);
 428
 429         /* Stop any running connections. */
 430         cancel_download(&fetcher->download, 0);
 431
 432         mem_free(fetcher);
 433 }
 434
 435 void
 436 done_bittorrent_fetch(struct bittorrent_fetcher **fetcher_ref)
 437 {
 438         struct bittorrent_fetcher *fetcher;
 439
 440         assert(fetcher_ref);
 441
 442         fetcher = *fetcher_ref;
 443         *fetcher_ref = NULL;
 444
 445         assert(fetcher);
 446
 447         if (fetcher->ref)
 448                 *fetcher->ref = NULL;
 449
 450         /* Nuke the callback so nothing gets called */
 451         fetcher->callback = NULL;
 452         register_bottom_half(end_bittorrent_fetch, fetcher);
 453 }
 454
 455
 456 /* ************************************************************************** */
 457 /* Blacklist management: */
 458 /* ************************************************************************** */
 459
 460 struct bittorrent_blacklist_item {
 461         LIST_HEAD(struct bittorrent_blacklist_item);
 462
 463         enum bittorrent_blacklist_flags flags;
 464         bittorrent_id_T id;
 465 };
 466
 467 static INIT_LIST_OF(struct bittorrent_blacklist_item, bittorrent_blacklist);
 468
 469
 470 static struct bittorrent_blacklist_item *
 471 get_bittorrent_blacklist_item(bittorrent_id_T peer_id)
 472 {
 473         struct bittorrent_blacklist_item *item;
 474
 475         foreach (item, bittorrent_blacklist)
 476                 if (!memcmp(item->id, peer_id, sizeof(bittorrent_id_T)))
 477                         return item;
 478
 479         return NULL;
 480 }
 481
 482 void
 483 add_bittorrent_blacklist_flags(bittorrent_id_T peer_id,
 484                                enum bittorrent_blacklist_flags flags)
 485 {
 486         struct bittorrent_blacklist_item *item;
 487
 488         item = get_bittorrent_blacklist_item(peer_id);
 489         if (item) {
 490                 item->flags |= flags;
 491                 return;
 492         }
 493
 494         item = mem_calloc(1, sizeof(*item));
 495         if (!item) return;
 496
 497         item->flags = flags;
 498         memcpy(item->id, peer_id, sizeof(bittorrent_id_T));
 499
 500         add_to_list(bittorrent_blacklist, item);
 501 }
 502
 503 void
 504 del_bittorrent_blacklist_flags(bittorrent_id_T peer_id,
 505                                enum bittorrent_blacklist_flags flags)
 506 {
 507         struct bittorrent_blacklist_item *item;
 508
 509         item = get_bittorrent_blacklist_item(peer_id);
 510         if (!item) return;
 511
 512         item->flags &= ~flags;
 513         if (item->flags) return;
 514
 515         del_from_list(item);
 516         mem_free(item);
 517 }
 518
 519 enum bittorrent_blacklist_flags
 520 get_bittorrent_blacklist_flags(bittorrent_id_T peer_id)
 521 {
 522         struct bittorrent_blacklist_item *item;
 523
 524         item = get_bittorrent_blacklist_item(peer_id);
 525
 526         return item ? item->flags : BITTORRENT_BLACKLIST_NONE;
 527 }
 528
 529 void
 530 done_bittorrent_blacklist(void)
 531 {
 532         free_list(bittorrent_blacklist);
 533 }