src/network/acl.c

   1 /*****************************************************************************
   2  * acl.c:
   3  *****************************************************************************
   4  * Copyright © 2005-2007 Rémi Denis-Courmont
   5  * $Id$
   6  *
   7  * Authors: Rémi Denis-Courmont <rem # videolan.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <vlc_common.h>
  32
  33 #include <ctype.h>
  34 #include <vlc_acl.h>
  35
  36 #include <errno.h>
  37
  38 #include <vlc_network.h>
  39 #include <vlc_charset.h>
  40
  41 /* FIXME: rwlock on acl, but libvlc doesn't implement rwlock */
  42 typedef struct vlc_acl_entry_t
  43 {
  44     uint8_t    host[17];
  45     uint8_t    i_bytes_match;
  46     uint8_t    i_bits_mask;
  47     bool b_allow;
  48 } vlc_acl_entry_t;
  49
  50 struct vlc_acl_t
  51 {
  52     vlc_object_t    *p_owner;
  53     unsigned         i_size;
  54     vlc_acl_entry_t *p_entries;
  55     bool       b_allow_default;
  56 };
  57
  58 static int ACL_Resolve( vlc_object_t *p_this, uint8_t *p_bytes,
  59                         const char *psz_ip )
  60 {
  61     struct addrinfo hints, *res;
  62     int i_family;
  63
  64     memset (&hints, 0, sizeof (hints));
  65     hints.ai_socktype = SOCK_STREAM; /* doesn't matter */
  66     hints.ai_flags = AI_NUMERICHOST;
  67
  68     if( vlc_getaddrinfo( p_this, psz_ip, 0, &hints, &res ) )
  69     {
  70         msg_Err( p_this, "invalid IP address %s", psz_ip );
  71         return -1;
  72     }
  73
  74     p_bytes[16] = 0; /* avoids overflowing when i_bytes_match = 16 */
  75
  76     i_family = res->ai_addr->sa_family;
  77     switch( i_family )
  78     {
  79         case AF_INET:
  80         {
  81             struct sockaddr_in *addr;
  82
  83             addr = (struct sockaddr_in *)res->ai_addr;
  84             memset( p_bytes, 0, 12 );
  85             memcpy( p_bytes + 12, &addr->sin_addr, 4 );
  86             break;
  87         }
  88
  89 #if defined (HAVE_GETADDRINFO) || defined (WIN32)
  90         /* unfortunately many people define AF_INET6
  91            though they don't have struct sockaddr_in6 */
  92         case AF_INET6:
  93         {
  94             struct sockaddr_in6 *addr;
  95
  96             addr = (struct sockaddr_in6 *)res->ai_addr;
  97             memcpy( p_bytes, &addr->sin6_addr, 16 );
  98             break;
  99         }
 100 #endif
 101
 102         default:
 103             msg_Err( p_this, "unknown address family" );
 104             vlc_freeaddrinfo( res );
 105             return -1;
 106     }
 107
 108     vlc_freeaddrinfo( res );
 109     return i_family;
 110 }
 111
 112
 113 /**
 114  * Check if a given address passes an access control list.
 115  *
 116  * @param p_acl pre-existing ACL to match the address against
 117  * @param psz_ip numeric IPv4/IPv6 address
 118  *
 119  * @return 0 if the first matching ACL entry is an access grant,
 120  * 1 if the first matching ACL entry is a denial of access,
 121  * -1 on error.
 122  */
 123 int ACL_Check( vlc_acl_t *p_acl, const char *psz_ip )
 124 {
 125     const vlc_acl_entry_t *p_cur, *p_end;
 126     uint8_t host[17];
 127
 128     if( p_acl == NULL )
 129         return -1;
 130
 131     p_cur = p_acl->p_entries;
 132     p_end = p_cur + p_acl->i_size;
 133
 134     if( ACL_Resolve( p_acl->p_owner, host, psz_ip ) < 0 )
 135         return -1;
 136
 137     while (p_cur < p_end)
 138     {
 139         unsigned i;
 140
 141         i = p_cur->i_bytes_match;
 142         if( (memcmp( p_cur->host, host, i ) == 0)
 143          && (((p_cur->host[i] ^ host[i]) & p_cur->i_bits_mask) == 0) )
 144             return !p_cur->b_allow;
 145
 146         p_cur++;
 147     }
 148
 149     return !p_acl->b_allow_default;
 150 }
 151
 152 /**
 153  * Adds an item to an ACL.
 154  * Items are always matched in the same order as they are added.
 155  */
 156 int ACL_AddNet( vlc_acl_t *p_acl, const char *psz_ip, int i_len,
 157                 bool b_allow )
 158 {
 159     vlc_acl_entry_t *p_ent;
 160     unsigned i_size;
 161     div_t d;
 162     int i_family;
 163
 164     i_size = p_acl->i_size;
 165     p_ent = (vlc_acl_entry_t *)realloc( p_acl->p_entries,
 166                                         ++p_acl->i_size * sizeof( *p_ent ) );
 167
 168     if( p_ent == NULL )
 169         return -1;
 170
 171     p_acl->p_entries = p_ent;
 172     p_ent += i_size;
 173
 174     i_family = ACL_Resolve( p_acl->p_owner, p_ent->host, psz_ip );
 175     if( i_family < 0 )
 176     {
 177         /*
 178          * I'm lazy : memory space will be re-used in the next ACL_Add call...
 179          * or not.
 180          */
 181         p_acl->i_size--;
 182         return -1;
 183     }
 184
 185     if( i_len >= 0 )
 186     {
 187         if( i_family == AF_INET )
 188             i_len += 96;
 189
 190         if( i_len > 128 )
 191             i_len = 128;
 192     }
 193     else
 194         i_len = 128; /* ACL_AddHost */
 195
 196     d = div( i_len, 8 );
 197     p_ent->i_bytes_match = d.quot;
 198     p_ent->i_bits_mask = 0xff << (8 - d.rem);
 199
 200     p_ent->b_allow = b_allow;
 201     return 0;
 202 }
 203
 204
 205 /**
 206  * Creates an empty ACL.
 207  *
 208  * @param b_allow whether to grant (true) or deny (false) access
 209  * by default (ie if none of the ACL entries matched).
 210  *
 211  * @return an ACL object. NULL in case of error.
 212  */
 213 vlc_acl_t *__ACL_Create( vlc_object_t *p_this, bool b_allow )
 214 {
 215     vlc_acl_t *p_acl;
 216
 217     p_acl = (vlc_acl_t *)malloc( sizeof( *p_acl ) );
 218     if( p_acl == NULL )
 219         return NULL;
 220
 221     vlc_object_yield( p_this );
 222     p_acl->p_owner = p_this;
 223     p_acl->i_size = 0;
 224     p_acl->p_entries = NULL;
 225     p_acl->b_allow_default = b_allow;
 226
 227     return p_acl;
 228 }
 229
 230
 231 /**
 232  * Perform a deep copy of an existing ACL.
 233  *
 234  * @param p_this object to attach the copy to.
 235  * @param p_acl ACL object to be copied.
 236  *
 237  * @return a new ACL object, or NULL on error.
 238  */
 239 vlc_acl_t *__ACL_Duplicate( vlc_object_t *p_this, const vlc_acl_t *p_acl )
 240 {
 241     vlc_acl_t *p_dupacl;
 242
 243     if( p_acl == NULL )
 244         return NULL;
 245
 246     p_dupacl = (vlc_acl_t *)malloc( sizeof( *p_dupacl ) );
 247     if( p_dupacl == NULL )
 248         return NULL;
 249
 250     if( p_acl->i_size )
 251     {
 252         p_dupacl->p_entries = (vlc_acl_entry_t *)
 253             malloc( p_acl->i_size * sizeof( vlc_acl_entry_t ) );
 254
 255         if( p_dupacl->p_entries == NULL )
 256         {
 257             free( p_dupacl );
 258             return NULL;
 259         }
 260
 261         memcpy( p_dupacl->p_entries, p_acl->p_entries,
 262                 p_acl->i_size * sizeof( vlc_acl_entry_t ) );
 263     }
 264     else
 265         p_dupacl->p_entries = NULL;
 266
 267     vlc_object_yield( p_this );
 268     p_dupacl->p_owner = p_this;
 269     p_dupacl->i_size = p_acl->i_size;
 270     p_dupacl->b_allow_default = p_acl->b_allow_default;
 271
 272     return p_dupacl;
 273 }
 274
 275
 276 /**
 277  * Releases all resources associated with an ACL object.
 278  */
 279 void ACL_Destroy( vlc_acl_t *p_acl )
 280 {
 281     if( p_acl != NULL )
 282     {
 283         if( p_acl->p_entries != NULL )
 284             free( p_acl->p_entries );
 285
 286         vlc_object_release( p_acl->p_owner );
 287         free( p_acl );
 288     }
 289 }
 290
 291
 292 /**
 293  * Reads ACL entries from a file.
 294  *
 295  * @param p_acl ACL object in which to insert parsed entries.
 296  * @param psz_patch filename from which to parse entries.
 297  *
 298  * @return 0 on success, -1 on error.
 299  */
 300 int ACL_LoadFile( vlc_acl_t *p_acl, const char *psz_path )
 301 {
 302     FILE *file;
 303
 304     if( p_acl == NULL )
 305         return -1;
 306
 307     file = utf8_fopen( psz_path, "r" );
 308     if( file == NULL )
 309         return -1;
 310
 311     msg_Dbg( p_acl->p_owner, "find .hosts in dir=%s", psz_path );
 312
 313     while( !feof( file ) )
 314     {
 315         char line[1024], *psz_ip, *ptr;
 316
 317         if( fgets( line, sizeof( line ), file ) == NULL )
 318         {
 319             if( ferror( file ) )
 320             {
 321                 msg_Err( p_acl->p_owner, "error reading %s : %m", psz_path );
 322                 goto error;
 323             }
 324             continue;
 325         }
 326
 327         /* fgets() is cool : never overflow, always nul-terminate */
 328         psz_ip = line;
 329
 330         /* skips blanks - cannot overflow given '\0' is not space */
 331         while( isspace( *psz_ip ) )
 332             psz_ip++;
 333
 334         if( *psz_ip == '\0' ) /* empty/blank line */
 335             continue;
 336
 337         ptr = strchr( psz_ip, '\n' );
 338         if( ptr == NULL )
 339         {
 340             msg_Warn( p_acl->p_owner, "skipping overly long line in %s",
 341                       psz_path);
 342             do
 343             {
 344                 if( fgets( line, sizeof( line ), file ) == NULL )
 345                 {
 346                      if( ferror( file ) )
 347                      {
 348                          msg_Err( p_acl->p_owner, "error reading %s : %m",
 349                                   psz_path );
 350                      }
 351                      goto error;
 352                 }
 353             }
 354             while( strchr( line, '\n' ) == NULL);
 355
 356             continue; /* skip unusable line */
 357         }
 358
 359         /* skips comment-only line */
 360         if( *psz_ip == '#' )
 361             continue;
 362
 363         /* looks for first space, CR, LF, etc. or end-of-line comment */
 364         /* (there is at least a linefeed) */
 365         for( ptr = psz_ip; ( *ptr != '#' ) && !isspace( *ptr ); ptr++ );
 366
 367         *ptr = '\0';
 368
 369         msg_Dbg( p_acl->p_owner, "restricted to %s", psz_ip );
 370
 371         ptr = strchr( psz_ip, '/' );
 372         if( ptr != NULL )
 373             *ptr++ = '\0'; /* separate address from mask length */
 374
 375         if( (ptr != NULL)
 376             ? ACL_AddNet( p_acl, psz_ip, atoi( ptr ), true )
 377             : ACL_AddHost( p_acl, psz_ip, true ) )
 378         {
 379             msg_Err( p_acl->p_owner, "cannot add ACL from %s", psz_path );
 380             continue;
 381         }
 382     }
 383
 384     fclose( file );
 385     return 0;
 386
 387 error:
 388     fclose( file );
 389     return -1;
 390 }
 391