Changeset 51bbec0
- Timestamp:
- 2008-05-21T10:27:28Z (17 years ago)
- Branches:
- master
- Children:
- 783e9b7
- Parents:
- a8d28d9
- Files:
-
- 2 edited
Legend:
- Unmodified
- Added
- Removed
-
lib/misc.c
ra8d28d9 r51bbec0 392 392 } 393 393 394 /* A pretty reliable random number generator. Tries to use the /dev/random 395 devices first, and falls back to the random number generator from libc 396 when it fails. Opens randomizer devices with O_NONBLOCK to make sure a 397 lack of entropy won't halt BitlBee. */ 398 void random_bytes( unsigned char *buf, int count ) 399 { 400 static int use_dev = -1; 401 402 /* Actually this probing code isn't really necessary, is it? */ 403 if( use_dev == -1 ) 404 { 405 if( access( "/dev/random", R_OK ) == 0 || access( "/dev/urandom", R_OK ) == 0 ) 406 use_dev = 1; 407 else 408 { 409 use_dev = 0; 410 srand( ( getpid() << 16 ) ^ time( NULL ) ); 411 } 412 } 413 414 if( use_dev ) 415 { 416 int fd; 417 418 /* At least on Linux, /dev/random can block if there's not 419 enough entropy. We really don't want that, so if it can't 420 give anything, use /dev/urandom instead. */ 421 if( ( fd = open( "/dev/random", O_RDONLY | O_NONBLOCK ) ) >= 0 ) 422 if( read( fd, buf, count ) == count ) 423 { 424 close( fd ); 425 return; 426 } 427 close( fd ); 428 429 /* urandom isn't supposed to block at all, but just to be 430 sure. If it blocks, we'll disable use_dev and use the libc 431 randomizer instead. */ 432 if( ( fd = open( "/dev/urandom", O_RDONLY | O_NONBLOCK ) ) >= 0 ) 433 if( read( fd, buf, count ) == count ) 434 { 435 close( fd ); 436 return; 437 } 438 close( fd ); 439 440 /* If /dev/random blocks once, we'll still try to use it 441 again next time. If /dev/urandom also fails for some 442 reason, stick with libc during this session. */ 443 444 use_dev = 0; 445 srand( ( getpid() << 16 ) ^ time( NULL ) ); 446 } 447 448 if( !use_dev ) 449 { 450 int i; 451 452 /* Possibly the LSB of rand() isn't very random on some 453 platforms. Seems okay on at least Linux and OSX though. */ 454 for( i = 0; i < count; i ++ ) 455 buf[i] = rand() & 0xff; 456 } 457 } 458 394 459 int is_bool( char *value ) 395 460 { -
unix.c
ra8d28d9 r51bbec0 219 219 return( (double) time->tv_sec + (double) time->tv_usec / 1000000 ); 220 220 } 221 222 /* A pretty reliable random number generator. Tries to use the /dev/random223 devices first, and falls back to the random number generator from libc224 when it fails. Opens randomizer devices with O_NONBLOCK to make sure a225 lack of entropy won't halt BitlBee. */226 void random_bytes( unsigned char *buf, int count )227 {228 static int use_dev = -1;229 230 /* Actually this probing code isn't really necessary, is it? */231 if( use_dev == -1 )232 {233 if( access( "/dev/random", R_OK ) == 0 || access( "/dev/urandom", R_OK ) == 0 )234 use_dev = 1;235 else236 {237 use_dev = 0;238 srand( ( getpid() << 16 ) ^ time( NULL ) );239 }240 }241 242 if( use_dev )243 {244 int fd;245 246 /* At least on Linux, /dev/random can block if there's not247 enough entropy. We really don't want that, so if it can't248 give anything, use /dev/urandom instead. */249 if( ( fd = open( "/dev/random", O_RDONLY | O_NONBLOCK ) ) >= 0 )250 if( read( fd, buf, count ) == count )251 {252 close( fd );253 return;254 }255 close( fd );256 257 /* urandom isn't supposed to block at all, but just to be258 sure. If it blocks, we'll disable use_dev and use the libc259 randomizer instead. */260 if( ( fd = open( "/dev/urandom", O_RDONLY | O_NONBLOCK ) ) >= 0 )261 if( read( fd, buf, count ) == count )262 {263 close( fd );264 return;265 }266 close( fd );267 268 /* If /dev/random blocks once, we'll still try to use it269 again next time. If /dev/urandom also fails for some270 reason, stick with libc during this session. */271 272 use_dev = 0;273 srand( ( getpid() << 16 ) ^ time( NULL ) );274 }275 276 if( !use_dev )277 {278 int i;279 280 /* Possibly the LSB of rand() isn't very random on some281 platforms. Seems okay on at least Linux and OSX though. */282 for( i = 0; i < count; i ++ )283 buf[i] = rand() & 0xff;284 }285 }286 287
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