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