libs/iwinfo/src/iwinfo_wext_scan.c

   1 /*
   2  * iwinfo - Wireless Information Library - Linux Wireless Extension Backend
   3  *
   4  *   Copyright (C) 2009 Jo-Philipp Wich <xm@subsignal.org>
   5  *
   6  * The iwinfo library is free software: you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License version 2
   8  * as published by the Free Software Foundation.
   9  *
  10  * The iwinfo library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  13  * See the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with the iwinfo library. If not, see http://www.gnu.org/licenses/.
  17  *
  18  * Parts of this code are derived from the Linux wireless tools, iwlib.c,
  19  * iwlist.c and iwconfig.c in particular.
  20  */
  21
  22 #include "iwinfo.h"
  23 #include "iwinfo_wext_scan.h"
  24
  25
  26 static int ioctl_socket = -1;
  27
  28 static int wext_ioctl(const char *ifname, int cmd, struct iwreq *wrq)
  29 {
  30         /* prepare socket */
  31         if( ioctl_socket == -1 )
  32                 ioctl_socket = socket(AF_INET, SOCK_DGRAM, 0);
  33
  34         strncpy(wrq->ifr_name, ifname, IFNAMSIZ);
  35         return ioctl(ioctl_socket, cmd, wrq);
  36 }
  37
  38 static double wext_freq2float(const struct iw_freq *in)
  39 {
  40         int             i;
  41         double  res = (double) in->m;
  42         for(i = 0; i < in->e; i++) res *= 10;
  43         return res;
  44 }
  45
  46 static int wext_extract_event(struct stream_descr *stream, struct iw_event *iwe)
  47 {
  48         const struct iw_ioctl_description *descr = NULL;
  49         int event_type = 0;
  50         unsigned int event_len = 1;
  51         char *pointer;
  52         unsigned cmd_index;             /* *MUST* be unsigned */
  53
  54         /* Check for end of stream */
  55         if((stream->current + IW_EV_LCP_PK_LEN) > stream->end)
  56                 return 0;
  57
  58         /* Extract the event header (to get the event id).
  59          * Note : the event may be unaligned, therefore copy... */
  60         memcpy((char *) iwe, stream->current, IW_EV_LCP_PK_LEN);
  61
  62         /* Check invalid events */
  63         if(iwe->len <= IW_EV_LCP_PK_LEN)
  64                 return -1;
  65
  66         /* Get the type and length of that event */
  67         if(iwe->cmd <= SIOCIWLAST)
  68         {
  69                 cmd_index = iwe->cmd - SIOCIWFIRST;
  70                 if(cmd_index < standard_ioctl_num)
  71                         descr = &(standard_ioctl_descr[cmd_index]);
  72         }
  73         else
  74         {
  75                 cmd_index = iwe->cmd - IWEVFIRST;
  76                 if(cmd_index < standard_event_num)
  77                         descr = &(standard_event_descr[cmd_index]);
  78         }
  79
  80         if(descr != NULL)
  81                 event_type = descr->header_type;
  82
  83         /* Unknown events -> event_type=0 => IW_EV_LCP_PK_LEN */
  84         event_len = event_type_size[event_type];
  85
  86         /* Check if we know about this event */
  87         if(event_len <= IW_EV_LCP_PK_LEN)
  88         {
  89                 /* Skip to next event */
  90                 stream->current += iwe->len;
  91                 return 2;
  92         }
  93
  94         event_len -= IW_EV_LCP_PK_LEN;
  95
  96         /* Set pointer on data */
  97         if(stream->value != NULL)
  98                 pointer = stream->value;                        /* Next value in event */
  99         else
 100                 pointer = stream->current + IW_EV_LCP_PK_LEN;   /* First value in event */
 101
 102         /* Copy the rest of the event (at least, fixed part) */
 103         if((pointer + event_len) > stream->end)
 104         {
 105                 /* Go to next event */
 106                 stream->current += iwe->len;
 107                 return -2;
 108         }
 109
 110         /* Fixup for WE-19 and later : pointer no longer in the stream */
 111         /* Beware of alignement. Dest has local alignement, not packed */
 112         if( event_type == IW_HEADER_TYPE_POINT )
 113                 memcpy((char *) iwe + IW_EV_LCP_LEN + IW_EV_POINT_OFF, pointer, event_len);
 114         else
 115                 memcpy((char *) iwe + IW_EV_LCP_LEN, pointer, event_len);
 116
 117         /* Skip event in the stream */
 118         pointer += event_len;
 119
 120         /* Special processing for iw_point events */
 121         if(event_type == IW_HEADER_TYPE_POINT)
 122         {
 123                 /* Check the length of the payload */
 124                 unsigned int extra_len = iwe->len - (event_len + IW_EV_LCP_PK_LEN);
 125                 if(extra_len > 0)
 126                 {
 127                         /* Set pointer on variable part (warning : non aligned) */
 128                         iwe->u.data.pointer = pointer;
 129
 130                         /* Check that we have a descriptor for the command */
 131                         if(descr == NULL)
 132                                 /* Can't check payload -> unsafe... */
 133                                 iwe->u.data.pointer = NULL;     /* Discard paylod */
 134                         else
 135                         {
 136                                 /* Those checks are actually pretty hard to trigger,
 137                                 * because of the checks done in the kernel... */
 138
 139                                 unsigned int    token_len = iwe->u.data.length * descr->token_size;
 140
 141                                 /* Ugly fixup for alignement issues.
 142                                 * If the kernel is 64 bits and userspace 32 bits,
 143                                 * we have an extra 4+4 bytes.
 144                                 * Fixing that in the kernel would break 64 bits userspace. */
 145                                 if((token_len != extra_len) && (extra_len >= 4))
 146                                 {
 147                                         uint16_t alt_dlen = *((uint16_t *) pointer);
 148                                         unsigned int alt_token_len = alt_dlen * descr->token_size;
 149                                         if((alt_token_len + 8) == extra_len)
 150                                         {
 151                                                 /* Ok, let's redo everything */
 152                                                 pointer -= event_len;
 153                                                 pointer += 4;
 154                                                 /* Dest has local alignement, not packed */
 155                                                 memcpy((char *) iwe + IW_EV_LCP_LEN + IW_EV_POINT_OFF, pointer, event_len);
 156                                                 pointer += event_len + 4;
 157                                                 iwe->u.data.pointer = pointer;
 158                                                 token_len = alt_token_len;
 159                                         }
 160                                 }
 161
 162                                 /* Discard bogus events which advertise more tokens than
 163                                 * what they carry... */
 164                                 if(token_len > extra_len)
 165                                         iwe->u.data.pointer = NULL;     /* Discard paylod */
 166
 167                                 /* Check that the advertised token size is not going to
 168                                 * produce buffer overflow to our caller... */
 169                                 if((iwe->u.data.length > descr->max_tokens)
 170                                 && !(descr->flags & IW_DESCR_FLAG_NOMAX))
 171                                         iwe->u.data.pointer = NULL;     /* Discard paylod */
 172
 173                                 /* Same for underflows... */
 174                                 if(iwe->u.data.length < descr->min_tokens)
 175                                         iwe->u.data.pointer = NULL;     /* Discard paylod */
 176                         }
 177                 }
 178                 else
 179                         /* No data */
 180                         iwe->u.data.pointer = NULL;
 181
 182                 /* Go to next event */
 183                 stream->current += iwe->len;
 184         }
 185         else
 186         {
 187                 /* Ugly fixup for alignement issues.
 188                 * If the kernel is 64 bits and userspace 32 bits,
 189                 * we have an extra 4 bytes.
 190                 * Fixing that in the kernel would break 64 bits userspace. */
 191                 if((stream->value == NULL)
 192                 && ((((iwe->len - IW_EV_LCP_PK_LEN) % event_len) == 4)
 193                 || ((iwe->len == 12) && ((event_type == IW_HEADER_TYPE_UINT) ||
 194                 (event_type == IW_HEADER_TYPE_QUAL))) ))
 195                 {
 196                         pointer -= event_len;
 197                         pointer += 4;
 198                         /* Beware of alignement. Dest has local alignement, not packed */
 199                         memcpy((char *) iwe + IW_EV_LCP_LEN, pointer, event_len);
 200                         pointer += event_len;
 201                 }
 202
 203                 /* Is there more value in the event ? */
 204                 if((pointer + event_len) <= (stream->current + iwe->len))
 205                         /* Go to next value */
 206                         stream->value = pointer;
 207                 else
 208                 {
 209                         /* Go to next event */
 210                         stream->value = NULL;
 211                         stream->current += iwe->len;
 212                 }
 213         }
 214
 215         return 1;
 216 }
 217
 218 static inline void wext_fill_wpa(unsigned char *iebuf, int buflen, struct iwinfo_scanlist_entry *e)
 219 {
 220         int ielen = iebuf[1] + 2;
 221         int offset = 2; /* Skip the IE id, and the length. */
 222         unsigned char wpa1_oui[3] = {0x00, 0x50, 0xf2};
 223         unsigned char wpa2_oui[3] = {0x00, 0x0f, 0xac};
 224         unsigned char *wpa_oui;
 225         int i;
 226         uint16_t ver = 0;
 227         uint16_t cnt = 0;
 228         int wpa1 = 0, wpa2 = 0;
 229         char buf[256];
 230
 231         struct iwinfo_crypto_entry *ce = &e->crypto;
 232
 233         if( !ce->enabled )
 234                 return;
 235
 236         //memset(&e->crypto, 0, sizeof(struct iwinfo_crypto_entry));
 237
 238         if(ielen > buflen)
 239                 ielen = buflen;
 240
 241         switch(iebuf[0])
 242         {
 243                 case 0x30:      /* WPA2 */
 244                         /* Check if we have enough data */
 245                         if(ielen < 4)
 246                                 return;
 247
 248                         wpa_oui = wpa2_oui;
 249                         break;
 250
 251                 case 0xdd:      /* WPA or else */
 252                         wpa_oui = wpa1_oui;
 253                         /* Not all IEs that start with 0xdd are WPA.
 254                         *        * So check that the OUI is valid. */
 255                         if((ielen < 8) || ((memcmp(&iebuf[offset], wpa_oui, 3) != 0)
 256                                 && (iebuf[offset+3] == 0x01)))
 257                                         return;
 258
 259                         offset += 4;
 260                         break;
 261
 262                 default:
 263                         return;
 264         }
 265
 266         /* Pick version number (little endian) */
 267         ver = iebuf[offset] | (iebuf[offset + 1] << 8);
 268         offset += 2;
 269
 270         if(iebuf[0] == 0xdd)
 271                 wpa1 = 1;
 272
 273         if(iebuf[0] == 0x30)
 274                 wpa2 = 1;
 275
 276         if( wpa1 && (ce->wpa_version == 2) )
 277                 ce->wpa_version = 3;
 278         else if( wpa2 && (ce->wpa_version == 1) )
 279                 ce->wpa_version = 3;
 280         else if( wpa1 && !ce->wpa_version )
 281                 ce->wpa_version = 1;
 282         else if( wpa2 && !ce->wpa_version )
 283                 ce->wpa_version = 2;
 284
 285         if(ielen < (offset + 4))
 286         {
 287                 ce->group_ciphers |= (1<<2); /* TKIP */
 288                 ce->pair_ciphers  |= (1<<2); /* TKIP */
 289                 ce->auth_suites   |= (1<<2); /* PSK */
 290                 return;
 291         }
 292
 293         if(memcmp(&iebuf[offset], wpa_oui, 3) != 0)
 294                 ce->group_ciphers |= (1<<7); /* Proprietary */
 295         else
 296                 ce->group_ciphers |= (1<<iebuf[offset+3]);
 297
 298         offset += 4;
 299
 300         if(ielen < (offset + 2))
 301         {
 302                 ce->pair_ciphers |= (1<<2); /* TKIP */
 303                 ce->auth_suites  |= (1<<2); /* PSK */
 304                 return;
 305         }
 306
 307         /* Otherwise, we have some number of pairwise ciphers. */
 308         cnt = iebuf[offset] | (iebuf[offset + 1] << 8);
 309         offset += 2;
 310
 311         if(ielen < (offset + 4*cnt))
 312                 return;
 313
 314         *buf = '\0';
 315         for(i = 0; i < cnt; i++)
 316         {
 317                 if(memcmp(&iebuf[offset], wpa_oui, 3) != 0)
 318                         ce->pair_ciphers |= (1<<7); /* Proprietary */
 319                 else if(iebuf[offset+3] <= IW_IE_CYPHER_NUM)
 320                         ce->pair_ciphers |= (1<<iebuf[offset+3]);
 321                 //else
 322                 //      ce->pair_ciphers[ce->pair_cipher_num++] = 255; /* Unknown */
 323
 324                 offset += 4;
 325         }
 326
 327         /* Check if we are done */
 328         if(ielen < (offset + 2))
 329                 return;
 330
 331         /* Now, we have authentication suites. */
 332         cnt = iebuf[offset] | (iebuf[offset + 1] << 8);
 333         offset += 2;
 334         *buf = '\0';
 335
 336         if(ielen < (offset + 4*cnt))
 337                 return;
 338
 339         for(i = 0; i < cnt; i++)
 340         {
 341                 if(memcmp(&iebuf[offset], wpa_oui, 3) != 0)
 342                         ce->auth_suites |= (1<<7); /* Proprietary */
 343                 else if(iebuf[offset+3] <= IW_IE_KEY_MGMT_NUM)
 344                         ce->auth_suites |= (1<<iebuf[offset+3]);
 345                 //else
 346                 //      ce->auth_suites[ce->auth_suite_num++] = 255; /* Unknown */
 347
 348                 offset += 4;
 349         }
 350 }
 351
 352
 353 static inline int wext_fill_entry(struct stream_descr *stream, struct iw_event *event,
 354         struct iw_range *iw_range, int has_range, struct iwinfo_scanlist_entry *e)
 355 {
 356         int i;
 357         double freq;
 358
 359         /* Now, let's decode the event */
 360         switch(event->cmd)
 361         {
 362                 case SIOCGIWAP:
 363                         memcpy(e->mac, &event->u.ap_addr.sa_data, 6);
 364                         break;
 365
 366                 case SIOCGIWFREQ:
 367                         if( event->u.freq.m >= 1000 )
 368                         {
 369                                 freq = wext_freq2float(&(event->u.freq));
 370
 371                                 for(i = 0; i < iw_range->num_frequency; i++)
 372                                 {
 373                                         if( wext_freq2float(&iw_range->freq[i]) == freq )
 374                                         {
 375                                                 e->channel = iw_range->freq[i].i;
 376                                                 break;
 377                                         }
 378                                 }
 379                         }
 380                         else
 381                         {
 382                                 e->channel = event->u.freq.m;
 383                         }
 384
 385                         break;
 386
 387                 case SIOCGIWMODE:
 388                         switch(event->u.mode)
 389                         {
 390                                 case 1:
 391                                         sprintf((char *) e->mode, "Ad-Hoc");
 392                                         break;
 393
 394                                 case 3:
 395                                         sprintf((char *) e->mode, "Master");
 396                                         break;
 397
 398                                 default:
 399                                         sprintf((char *) e->mode, "Unknown");
 400                         }
 401
 402                         break;
 403
 404                 case SIOCGIWESSID:
 405                         if( event->u.essid.pointer && event->u.essid.length && event->u.essid.flags )
 406                                 memcpy(e->ssid, event->u.essid.pointer, event->u.essid.length);
 407
 408                         break;
 409
 410                 case SIOCGIWENCODE:
 411                         e->crypto.enabled = !(event->u.data.flags & IW_ENCODE_DISABLED);
 412                         break;
 413
 414 #if 0
 415                 case SIOCGIWRATE:
 416                         if(state->val_index == 0)
 417                         {
 418                                 lua_pushstring(L, "bitrates");
 419                                 lua_newtable(L);
 420                         }
 421                         //iw_print_bitrate(buffer, sizeof(buffer), event->u.bitrate.value);
 422                         snprintf(buffer, sizeof(buffer), "%d", event->u.bitrate.value);
 423                         lua_pushinteger(L, state->val_index + 1);
 424                         lua_pushstring(L, buffer);
 425                         lua_settable(L, -3);
 426
 427                         /* Check for termination */
 428                         if(stream->value == NULL)
 429                         {
 430                                 lua_settable(L, -3);
 431                                 state->val_index = 0;
 432                         } else
 433                                 state->val_index++;
 434                         break;
 435 #endif
 436                  case IWEVGENIE:
 437                         i = 0;
 438
 439                         while(i <= (event->u.data.length - 2))
 440                         {
 441                                 switch(((unsigned char *)event->u.data.pointer)[i])
 442                                 {
 443                                         case 0xdd:  /* WPA1 (and other) */
 444                                         case 0x30:  /* WPA2 */
 445                                                 wext_fill_wpa((unsigned char *)event->u.data.pointer + i,
 446                                                         event->u.data.length, e);
 447
 448                                                 break;
 449                                 }
 450
 451                                 i += ((unsigned char *)event->u.data.pointer)[i+1] + 2;
 452                         }
 453
 454                         break;
 455         }
 456
 457         return 0;
 458 }
 459
 460
 461 int wext_get_scanlist(const char *ifname, char *buf, int *len)
 462 {
 463         struct iwreq wrq;
 464         struct iw_scan_req scanopt;        /* Options for 'set' */
 465         //int scanflags = 0;      /* Flags for scan */
 466         unsigned char *buffer = NULL;      /* Results */
 467         int buflen = IW_SCAN_MAX_DATA; /* Min for compat WE<17 */
 468         struct iw_range range;
 469         int has_range = 1;
 470         struct timeval tv;             /* Select timeout */
 471         int timeout = 15000000;     /* 15s */
 472
 473         int entrylen = 0;
 474         struct iwinfo_scanlist_entry e;
 475
 476         //IWINFO_BUFSIZE
 477         wrq.u.data.pointer = (caddr_t) &range;
 478         wrq.u.data.length  = sizeof(struct iw_range);
 479         wrq.u.data.flags   = 0;
 480
 481         if( wext_ioctl(ifname, SIOCGIWRANGE, &wrq) >= 0 )
 482         {
 483                 /* Init timeout value -> 250ms between set and first get */
 484                 tv.tv_sec  = 0;
 485                 tv.tv_usec = 250000;
 486
 487                 /* Clean up set args */
 488                 memset(&scanopt, 0, sizeof(scanopt));
 489
 490                 wrq.u.data.pointer = NULL;
 491                 wrq.u.data.flags   = 0;
 492                 wrq.u.data.length  = 0;
 493
 494                 /* Initiate Scanning */
 495                 if( wext_ioctl(ifname, SIOCSIWSCAN, &wrq) >= 0 )
 496                 {
 497                         timeout -= tv.tv_usec;
 498
 499                         /* Forever */
 500                         while(1)
 501                         {
 502                                 fd_set rfds;       /* File descriptors for select */
 503                                 int last_fd;    /* Last fd */
 504                                 int ret;
 505
 506                                 /* Guess what ? We must re-generate rfds each time */
 507                                 FD_ZERO(&rfds);
 508                                 last_fd = -1;
 509                                 /* In here, add the rtnetlink fd in the list */
 510
 511                                 /* Wait until something happens */
 512                                 ret = select(last_fd + 1, &rfds, NULL, NULL, &tv);
 513
 514                                 /* Check if there was an error */
 515                                 if(ret < 0)
 516                                 {
 517                                         if(errno == EAGAIN || errno == EINTR)
 518                                                 continue;
 519
 520                                         return -1;
 521                                 }
 522
 523                                 /* Check if there was a timeout */
 524                                 if(ret == 0)
 525                                 {
 526                                         unsigned char *newbuf;
 527
 528                 realloc:
 529                                         /* (Re)allocate the buffer - realloc(NULL, len) == malloc(len) */
 530                                         newbuf = realloc(buffer, buflen);
 531                                         if(newbuf == NULL)
 532                                         {
 533                                                 if(buffer)
 534                                                         free(buffer);
 535
 536                                                 return -1;
 537                                         }
 538
 539                                         buffer = newbuf;
 540
 541                                         /* Try to read the results */
 542                                         wrq.u.data.pointer = buffer;
 543                                         wrq.u.data.flags   = 0;
 544                                         wrq.u.data.length  = buflen;
 545
 546                                         if( wext_ioctl(ifname, SIOCGIWSCAN, &wrq) )
 547                                         {
 548                                                 /* Check if buffer was too small (WE-17 only) */
 549                                                 if((errno == E2BIG) && (range.we_version_compiled > 16))
 550                                                 {
 551                                                         /* Some driver may return very large scan results, either
 552                                                          * because there are many cells, or because they have many
 553                                                          * large elements in cells (like IWEVCUSTOM). Most will
 554                                                          * only need the regular sized buffer. We now use a dynamic
 555                                                          * allocation of the buffer to satisfy everybody. Of course,
 556                                                          * as we don't know in advance the size of the array, we try
 557                                                          * various increasing sizes. Jean II */
 558
 559                                                         /* Check if the driver gave us any hints. */
 560                                                         if(wrq.u.data.length > buflen)
 561                                                                 buflen = wrq.u.data.length;
 562                                                         else
 563                                                                 buflen *= 2;
 564
 565                                                         /* Try again */
 566                                                         goto realloc;
 567                                                 }
 568
 569                                                 /* Check if results not available yet */
 570                                                 if(errno == EAGAIN)
 571                                                 {
 572                                                         /* Restart timer for only 100ms*/
 573                                                         tv.tv_sec = 0;
 574                                                         tv.tv_usec = 100000;
 575                                                         timeout -= tv.tv_usec;
 576
 577                                                         if(timeout > 0)
 578                                                                 continue;   /* Try again later */
 579                                                 }
 580
 581                                                 /* Bad error */
 582                                                 free(buffer);
 583                                                 return -1;
 584
 585                                         } else {
 586                                                 /* We have the results, go to process them */
 587                                                 break;
 588                                         }
 589                                 }
 590                         }
 591
 592                         if( wrq.u.data.length )
 593                         {
 594                                 struct iw_event       iwe;
 595                                 struct stream_descr   stream;
 596                                 int ret;
 597                                 int first = 1;
 598
 599                                 memset(&stream, 0, sizeof(stream));
 600                                 stream.current = (char *)buffer;
 601                                 stream.end     = (char *)buffer + wrq.u.data.length;
 602
 603                                 do
 604                                 {
 605                                         /* Extract an event and print it */
 606                                         ret = wext_extract_event(&stream, &iwe);
 607
 608                                         if(ret >= 0)
 609                                         {
 610                                                 if( (iwe.cmd == SIOCGIWAP) || (ret == 0) )
 611                                                 {
 612                                                         if( first )
 613                                                         {
 614                                                                 first = 0;
 615                                                         }
 616                                                         else if( (entrylen + sizeof(struct iwinfo_scanlist_entry)) <= IWINFO_BUFSIZE )
 617                                                         {
 618                                                                 memcpy(&buf[entrylen], &e, sizeof(struct iwinfo_scanlist_entry));
 619                                                                 entrylen += sizeof(struct iwinfo_scanlist_entry);
 620                                                         }
 621                                                         else
 622                                                         {
 623                                                                 /* we exceed the callers buffer size, abort here ... */
 624                                                                 break;
 625                                                         }
 626
 627                                                         memset(&e, 0, sizeof(struct iwinfo_scanlist_entry));
 628                                                 }
 629
 630                                                 wext_fill_entry(&stream, &iwe, &range, has_range, &e);
 631                                         }
 632
 633                                 } while(ret > 0);
 634
 635                                 free(buffer);
 636                                 *len = entrylen;
 637                                 return 0;
 638                         }
 639
 640                         free(buffer);
 641                         return 0;
 642                 }
 643         }
 644
 645         return -1;
 646 }
 647