iwinfo_wext_scan.c

   1 /*
   2  * iwinfo - Wireless Information Library - Linux Wireless Extension Backend
   3  *
   4  *   Copyright (C) 2009-2010 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.h"
  24
  25
  26 static int wext_ioctl(const char *ifname, int cmd, struct iwreq *wrq)
  27 {
  28         strncpy(wrq->ifr_name, ifname, IFNAMSIZ - 1);
  29         return iwinfo_ioctl(cmd, wrq);
  30 }
  31
  32 static inline double wext_freq2float(const struct iw_freq *in)
  33 {
  34         int             i;
  35         double  res = (double) in->m;
  36         for(i = 0; i < in->e; i++) res *= 10;
  37         return res;
  38 }
  39
  40 static inline int wext_extract_event(struct stream_descr *stream, struct iw_event *iwe, int wev)
  41 {
  42         const struct iw_ioctl_description *descr = NULL;
  43         int event_type = 0;
  44         unsigned int event_len = 1;
  45         char *pointer;
  46         unsigned cmd_index;             /* *MUST* be unsigned */
  47
  48         /* Check for end of stream */
  49         if((stream->current + IW_EV_LCP_PK_LEN) > stream->end)
  50                 return 0;
  51
  52         /* Extract the event header (to get the event id).
  53          * Note : the event may be unaligned, therefore copy... */
  54         memcpy((char *) iwe, stream->current, IW_EV_LCP_PK_LEN);
  55
  56         /* Check invalid events */
  57         if(iwe->len <= IW_EV_LCP_PK_LEN)
  58                 return -1;
  59
  60         /* Get the type and length of that event */
  61         if(iwe->cmd <= SIOCIWLAST)
  62         {
  63                 cmd_index = iwe->cmd - SIOCIWFIRST;
  64                 if(cmd_index < standard_ioctl_num)
  65                         descr = &(standard_ioctl_descr[cmd_index]);
  66         }
  67         else
  68         {
  69                 cmd_index = iwe->cmd - IWEVFIRST;
  70                 if(cmd_index < standard_event_num)
  71                         descr = &(standard_event_descr[cmd_index]);
  72         }
  73
  74         if(descr != NULL)
  75                 event_type = descr->header_type;
  76
  77         /* Unknown events -> event_type=0 => IW_EV_LCP_PK_LEN */
  78         event_len = event_type_size[event_type];
  79
  80         /* Fixup for earlier version of WE */
  81         if((wev <= 18) && (event_type == IW_HEADER_TYPE_POINT))
  82                 event_len += IW_EV_POINT_OFF;
  83
  84         /* Check if we know about this event */
  85         if(event_len <= IW_EV_LCP_PK_LEN)
  86         {
  87                 /* Skip to next event */
  88                 stream->current += iwe->len;
  89                 return 2;
  90         }
  91
  92         event_len -= IW_EV_LCP_PK_LEN;
  93
  94         /* Set pointer on data */
  95         if(stream->value != NULL)
  96                 pointer = stream->value;                        /* Next value in event */
  97         else
  98                 pointer = stream->current + IW_EV_LCP_PK_LEN;   /* First value in event */
  99
 100         /* Copy the rest of the event (at least, fixed part) */
 101         if((pointer + event_len) > stream->end)
 102         {
 103                 /* Go to next event */
 104                 stream->current += iwe->len;
 105                 return -2;
 106         }
 107
 108         /* Fixup for WE-19 and later : pointer no longer in the stream */
 109         /* Beware of alignement. Dest has local alignement, not packed */
 110         if( (wev > 18) && (event_type == IW_HEADER_TYPE_POINT) )
 111                 memcpy((char *) iwe + IW_EV_LCP_LEN + IW_EV_POINT_OFF, pointer, event_len);
 112         else
 113                 memcpy((char *) iwe + IW_EV_LCP_LEN, pointer, event_len);
 114
 115         /* Skip event in the stream */
 116         pointer += event_len;
 117
 118         /* Special processing for iw_point events */
 119         if(event_type == IW_HEADER_TYPE_POINT)
 120         {
 121                 /* Check the length of the payload */
 122                 unsigned int extra_len = iwe->len - (event_len + IW_EV_LCP_PK_LEN);
 123                 if(extra_len > 0)
 124                 {
 125                         /* Set pointer on variable part (warning : non aligned) */
 126                         iwe->u.data.pointer = pointer;
 127
 128                         /* Check that we have a descriptor for the command */
 129                         if(descr == NULL)
 130                                 /* Can't check payload -> unsafe... */
 131                                 iwe->u.data.pointer = NULL;     /* Discard paylod */
 132                         else
 133                         {
 134                                 /* Those checks are actually pretty hard to trigger,
 135                                 * because of the checks done in the kernel... */
 136
 137                                 unsigned int    token_len = iwe->u.data.length * descr->token_size;
 138
 139                                 /* Ugly fixup for alignement issues.
 140                                 * If the kernel is 64 bits and userspace 32 bits,
 141                                 * we have an extra 4+4 bytes.
 142                                 * Fixing that in the kernel would break 64 bits userspace. */
 143                                 if((token_len != extra_len) && (extra_len >= 4))
 144                                 {
 145                                         uint16_t alt_dlen = *((uint16_t *) pointer);
 146                                         unsigned int alt_token_len = alt_dlen * descr->token_size;
 147                                         if((alt_token_len + 8) == extra_len)
 148                                         {
 149                                                 /* Ok, let's redo everything */
 150                                                 pointer -= event_len;
 151                                                 pointer += 4;
 152                                                 /* Dest has local alignement, not packed */
 153                                                 memcpy((char *) iwe + IW_EV_LCP_LEN + IW_EV_POINT_OFF, pointer, event_len);
 154                                                 pointer += event_len + 4;
 155                                                 iwe->u.data.pointer = pointer;
 156                                                 token_len = alt_token_len;
 157                                         }
 158                                 }
 159
 160                                 /* Discard bogus events which advertise more tokens than
 161                                 * what they carry... */
 162                                 if(token_len > extra_len)
 163                                         iwe->u.data.pointer = NULL;     /* Discard paylod */
 164
 165                                 /* Check that the advertised token size is not going to
 166                                 * produce buffer overflow to our caller... */
 167                                 if((iwe->u.data.length > descr->max_tokens)
 168                                 && !(descr->flags & IW_DESCR_FLAG_NOMAX))
 169                                         iwe->u.data.pointer = NULL;     /* Discard paylod */
 170
 171                                 /* Same for underflows... */
 172                                 if(iwe->u.data.length < descr->min_tokens)
 173                                         iwe->u.data.pointer = NULL;     /* Discard paylod */
 174                         }
 175                 }
 176                 else
 177                         /* No data */
 178                         iwe->u.data.pointer = NULL;
 179
 180                 /* Go to next event */
 181                 stream->current += iwe->len;
 182         }
 183         else
 184         {
 185                 /* Ugly fixup for alignement issues.
 186                 * If the kernel is 64 bits and userspace 32 bits,
 187                 * we have an extra 4 bytes.
 188                 * Fixing that in the kernel would break 64 bits userspace. */
 189                 if((stream->value == NULL)
 190                 && ((((iwe->len - IW_EV_LCP_PK_LEN) % event_len) == 4)
 191                 || ((iwe->len == 12) && ((event_type == IW_HEADER_TYPE_UINT) ||
 192                 (event_type == IW_HEADER_TYPE_QUAL))) ))
 193                 {
 194                         pointer -= event_len;
 195                         pointer += 4;
 196                         /* Beware of alignement. Dest has local alignement, not packed */
 197                         memcpy((char *) iwe + IW_EV_LCP_LEN, pointer, event_len);
 198                         pointer += event_len;
 199                 }
 200
 201                 /* Is there more value in the event ? */
 202                 if((pointer + event_len) <= (stream->current + iwe->len))
 203                         /* Go to next value */
 204                         stream->value = pointer;
 205                 else
 206                 {
 207                         /* Go to next event */
 208                         stream->value = NULL;
 209                         stream->current += iwe->len;
 210                 }
 211         }
 212
 213         return 1;
 214 }
 215
 216 static inline void wext_fill_wpa(unsigned char *iebuf, int ielen, struct iwinfo_scanlist_entry *e)
 217 {
 218         static unsigned char ms_oui[3] = { 0x00, 0x50, 0xf2 };
 219
 220         while (ielen >= 2 && ielen >= iebuf[1])
 221         {
 222                 switch (iebuf[0])
 223                 {
 224                 case 48: /* RSN */
 225                         iwinfo_parse_rsn(&e->crypto, iebuf + 2, iebuf[1],
 226                                          IWINFO_CIPHER_CCMP, IWINFO_KMGMT_8021x);
 227                         break;
 228
 229                 case 221: /* Vendor */
 230                         if (iebuf[1] >= 4 && !memcmp(iebuf + 2, ms_oui, 3) && iebuf[5] == 1)
 231                                 iwinfo_parse_rsn(&e->crypto, iebuf + 6, iebuf[1] - 4,
 232                                                  IWINFO_CIPHER_TKIP, IWINFO_KMGMT_PSK);
 233                         break;
 234                 }
 235
 236                 ielen -= iebuf[1] + 2;
 237                 iebuf += iebuf[1] + 2;
 238         }
 239 }
 240
 241
 242 static inline void wext_fill_entry(struct stream_descr *stream, struct iw_event *event,
 243         struct iw_range *iw_range, int has_range, struct iwinfo_scanlist_entry *e)
 244 {
 245         int i;
 246         double freq;
 247
 248         /* Now, let's decode the event */
 249         switch(event->cmd)
 250         {
 251                 case SIOCGIWAP:
 252                         memcpy(e->mac, &event->u.ap_addr.sa_data, 6);
 253                         break;
 254
 255                 case SIOCGIWFREQ:
 256                         if( event->u.freq.m >= 1000 )
 257                         {
 258                                 freq = wext_freq2float(&(event->u.freq));
 259
 260                                 for(i = 0; i < iw_range->num_frequency; i++)
 261                                 {
 262                                         if( wext_freq2float(&iw_range->freq[i]) == freq )
 263                                         {
 264                                                 e->channel = iw_range->freq[i].i;
 265                                                 break;
 266                                         }
 267                                 }
 268                         }
 269                         else
 270                         {
 271                                 e->channel = event->u.freq.m;
 272                         }
 273
 274                         break;
 275
 276                 case SIOCGIWMODE:
 277                         switch(event->u.mode)
 278                         {
 279                                 case 1:
 280                                         e->mode = IWINFO_OPMODE_ADHOC;
 281                                         break;
 282
 283                                 case 2:
 284                                 case 3:
 285                                         e->mode = IWINFO_OPMODE_MASTER;
 286                                         break;
 287
 288                                 default:
 289                                         e->mode = IWINFO_OPMODE_UNKNOWN;
 290                                         break;
 291                         }
 292
 293                         break;
 294
 295                 case SIOCGIWESSID:
 296                         if( event->u.essid.pointer && event->u.essid.length && event->u.essid.flags )
 297                                 memcpy(e->ssid, event->u.essid.pointer, event->u.essid.length);
 298
 299                         break;
 300
 301                 case SIOCGIWENCODE:
 302                         e->crypto.enabled = !(event->u.data.flags & IW_ENCODE_DISABLED);
 303                         break;
 304
 305                 case IWEVQUAL:
 306                         e->signal = event->u.qual.level;
 307                         e->quality = event->u.qual.qual;
 308                         e->quality_max = iw_range->max_qual.qual;
 309                         break;
 310 #if 0
 311                 case SIOCGIWRATE:
 312                         if(state->val_index == 0)
 313                         {
 314                                 lua_pushstring(L, "bitrates");
 315                                 lua_newtable(L);
 316                         }
 317                         //iw_print_bitrate(buffer, sizeof(buffer), event->u.bitrate.value);
 318                         snprintf(buffer, sizeof(buffer), "%d", event->u.bitrate.value);
 319                         lua_pushinteger(L, state->val_index + 1);
 320                         lua_pushstring(L, buffer);
 321                         lua_settable(L, -3);
 322
 323                         /* Check for termination */
 324                         if(stream->value == NULL)
 325                         {
 326                                 lua_settable(L, -3);
 327                                 state->val_index = 0;
 328                         } else
 329                                 state->val_index++;
 330                         break;
 331 #endif
 332                  case IWEVGENIE:
 333                         wext_fill_wpa(event->u.data.pointer, event->u.data.length, e);
 334                         break;
 335         }
 336 }
 337
 338
 339 int wext_get_scanlist(const char *ifname, char *buf, int *len)
 340 {
 341         struct iwreq wrq;
 342         struct iw_scan_req scanopt;        /* Options for 'set' */
 343         unsigned char *buffer = NULL;      /* Results */
 344         int buflen = IW_SCAN_MAX_DATA; /* Min for compat WE<17 */
 345         struct iw_range range;
 346         int has_range = 1;
 347         struct timeval tv;             /* Select timeout */
 348         int timeout = 15000000;     /* 15s */
 349
 350         int entrylen = 0;
 351         struct iwinfo_scanlist_entry e;
 352
 353         wrq.u.data.pointer = (caddr_t) &range;
 354         wrq.u.data.length  = sizeof(struct iw_range);
 355         wrq.u.data.flags   = 0;
 356
 357         if( wext_ioctl(ifname, SIOCGIWRANGE, &wrq) >= 0 )
 358         {
 359                 /* Init timeout value -> 250ms between set and first get */
 360                 tv.tv_sec  = 0;
 361                 tv.tv_usec = 250000;
 362
 363                 /* Clean up set args */
 364                 memset(&scanopt, 0, sizeof(scanopt));
 365
 366                 wrq.u.data.pointer = NULL;
 367                 wrq.u.data.flags   = 0;
 368                 wrq.u.data.length  = 0;
 369
 370                 /* Initiate Scanning */
 371                 if( wext_ioctl(ifname, SIOCSIWSCAN, &wrq) >= 0 )
 372                 {
 373                         timeout -= tv.tv_usec;
 374
 375                         /* Forever */
 376                         while(1)
 377                         {
 378                                 fd_set rfds;       /* File descriptors for select */
 379                                 int last_fd;    /* Last fd */
 380                                 int ret;
 381
 382                                 /* Guess what ? We must re-generate rfds each time */
 383                                 FD_ZERO(&rfds);
 384                                 last_fd = -1;
 385                                 /* In here, add the rtnetlink fd in the list */
 386
 387                                 /* Wait until something happens */
 388                                 ret = select(last_fd + 1, &rfds, NULL, NULL, &tv);
 389
 390                                 /* Check if there was an error */
 391                                 if(ret < 0)
 392                                 {
 393                                         if(errno == EAGAIN || errno == EINTR)
 394                                                 continue;
 395
 396                                         return -1;
 397                                 }
 398
 399                                 /* Check if there was a timeout */
 400                                 if(ret == 0)
 401                                 {
 402                                         unsigned char *newbuf;
 403
 404                 realloc:
 405                                         /* (Re)allocate the buffer - realloc(NULL, len) == malloc(len) */
 406                                         newbuf = realloc(buffer, buflen);
 407                                         if(newbuf == NULL)
 408                                         {
 409                                                 if(buffer)
 410                                                         free(buffer);
 411
 412                                                 return -1;
 413                                         }
 414
 415                                         buffer = newbuf;
 416
 417                                         /* Try to read the results */
 418                                         wrq.u.data.pointer = buffer;
 419                                         wrq.u.data.flags   = 0;
 420                                         wrq.u.data.length  = buflen;
 421
 422                                         if( wext_ioctl(ifname, SIOCGIWSCAN, &wrq) )
 423                                         {
 424                                                 /* Check if buffer was too small (WE-17 only) */
 425                                                 if((errno == E2BIG) && (range.we_version_compiled > 16))
 426                                                 {
 427                                                         /* Some driver may return very large scan results, either
 428                                                          * because there are many cells, or because they have many
 429                                                          * large elements in cells (like IWEVCUSTOM). Most will
 430                                                          * only need the regular sized buffer. We now use a dynamic
 431                                                          * allocation of the buffer to satisfy everybody. Of course,
 432                                                          * as we don't know in advance the size of the array, we try
 433                                                          * various increasing sizes. Jean II */
 434
 435                                                         /* Check if the driver gave us any hints. */
 436                                                         if(wrq.u.data.length > buflen)
 437                                                                 buflen = wrq.u.data.length;
 438                                                         else
 439                                                                 buflen *= 2;
 440
 441                                                         /* Try again */
 442                                                         goto realloc;
 443                                                 }
 444
 445                                                 /* Check if results not available yet */
 446                                                 if(errno == EAGAIN)
 447                                                 {
 448                                                         /* Restart timer for only 100ms*/
 449                                                         tv.tv_sec = 0;
 450                                                         tv.tv_usec = 100000;
 451                                                         timeout -= tv.tv_usec;
 452
 453                                                         if(timeout > 0)
 454                                                                 continue;   /* Try again later */
 455                                                 }
 456
 457                                                 /* Bad error */
 458                                                 free(buffer);
 459                                                 return -1;
 460
 461                                         } else {
 462                                                 /* We have the results, go to process them */
 463                                                 break;
 464                                         }
 465                                 }
 466                         }
 467
 468                         if( wrq.u.data.length )
 469                         {
 470                                 struct iw_event       iwe;
 471                                 struct stream_descr   stream;
 472                                 int ret;
 473                                 int first = 1;
 474
 475                                 memset(&stream, 0, sizeof(stream));
 476                                 stream.current = (char *)buffer;
 477                                 stream.end     = (char *)buffer + wrq.u.data.length;
 478
 479                                 do
 480                                 {
 481                                         /* Extract an event and print it */
 482                                         ret = wext_extract_event(&stream, &iwe, range.we_version_compiled);
 483
 484                                         if(ret >= 0)
 485                                         {
 486                                                 if( (iwe.cmd == SIOCGIWAP) || (ret == 0) )
 487                                                 {
 488                                                         if( first )
 489                                                         {
 490                                                                 first = 0;
 491                                                         }
 492                                                         else if( (entrylen + sizeof(struct iwinfo_scanlist_entry)) <= IWINFO_BUFSIZE )
 493                                                         {
 494                                                                 /* if encryption is off, clear the crypto strunct */
 495                                                                 if( !e.crypto.enabled )
 496                                                                         memset(&e.crypto, 0, sizeof(struct iwinfo_crypto_entry));
 497
 498                                                                 memcpy(&buf[entrylen], &e, sizeof(struct iwinfo_scanlist_entry));
 499                                                                 entrylen += sizeof(struct iwinfo_scanlist_entry);
 500                                                         }
 501                                                         else
 502                                                         {
 503                                                                 /* we exceed the callers buffer size, abort here ... */
 504                                                                 break;
 505                                                         }
 506
 507                                                         memset(&e, 0, sizeof(struct iwinfo_scanlist_entry));
 508                                                 }
 509
 510                                                 wext_fill_entry(&stream, &iwe, &range, has_range, &e);
 511                                         }
 512
 513                                 } while(ret > 0);
 514
 515                                 free(buffer);
 516                                 *len = entrylen;
 517                                 return 0;
 518                         }
 519
 520                         *len = 0;
 521                         free(buffer);
 522                         return 0;
 523                 }
 524         }
 525
 526         return -1;
 527 }