Changes in / [1a57b893:0a14b8c]
- Files:
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- 2 edited
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- Added
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lib/misc.c
r1a57b893 r0a14b8c 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
r1a57b893 r0a14b8c 225 225 return( (double) time->tv_sec + (double) time->tv_usec / 1000000 ); 226 226 } 227 228 /* A pretty reliable random number generator. Tries to use the /dev/random229 devices first, and falls back to the random number generator from libc230 when it fails. Opens randomizer devices with O_NONBLOCK to make sure a231 lack of entropy won't halt BitlBee. */232 void random_bytes( unsigned char *buf, int count )233 {234 static int use_dev = -1;235 236 /* Actually this probing code isn't really necessary, is it? */237 if( use_dev == -1 )238 {239 if( access( "/dev/random", R_OK ) == 0 || access( "/dev/urandom", R_OK ) == 0 )240 use_dev = 1;241 else242 {243 use_dev = 0;244 srand( ( getpid() << 16 ) ^ time( NULL ) );245 }246 }247 248 if( use_dev )249 {250 int fd;251 252 /* At least on Linux, /dev/random can block if there's not253 enough entropy. We really don't want that, so if it can't254 give anything, use /dev/urandom instead. */255 if( ( fd = open( "/dev/random", O_RDONLY | O_NONBLOCK ) ) >= 0 )256 if( read( fd, buf, count ) == count )257 {258 close( fd );259 return;260 }261 close( fd );262 263 /* urandom isn't supposed to block at all, but just to be264 sure. If it blocks, we'll disable use_dev and use the libc265 randomizer instead. */266 if( ( fd = open( "/dev/urandom", O_RDONLY | O_NONBLOCK ) ) >= 0 )267 if( read( fd, buf, count ) == count )268 {269 close( fd );270 return;271 }272 close( fd );273 274 /* If /dev/random blocks once, we'll still try to use it275 again next time. If /dev/urandom also fails for some276 reason, stick with libc during this session. */277 278 use_dev = 0;279 srand( ( getpid() << 16 ) ^ time( NULL ) );280 }281 282 if( !use_dev )283 {284 int i;285 286 /* Possibly the LSB of rand() isn't very random on some287 platforms. Seems okay on at least Linux and OSX though. */288 for( i = 0; i < count; i ++ )289 buf[i] = rand() & 0xff;290 }291 }292 293
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