diff options
Diffstat (limited to 'third_party/srtp/crypto/rng/rand_source.c')
| -rw-r--r-- | third_party/srtp/crypto/rng/rand_source.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/third_party/srtp/crypto/rng/rand_source.c b/third_party/srtp/crypto/rng/rand_source.c new file mode 100644 index 00000000..79ec398d --- /dev/null +++ b/third_party/srtp/crypto/rng/rand_source.c @@ -0,0 +1,153 @@ +/* + * rand_source.c + * + * implements a random source based on /dev/random + * + * David A. McGrew + * Cisco Systems, Inc. + */ +/* + * + * Copyright(c) 2001-2006 Cisco Systems, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * + * Neither the name of the Cisco Systems, Inc. nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +#include "srtp_config.h" + +#ifdef DEV_URANDOM +# include <fcntl.h> /* for open() */ +# include <unistd.h> /* for close() */ +#elif (_MSC_VER >= 1400) +#define _CRT_RAND_S +# include <stdlib.h> +# include <stdio.h> +#else +# include <stdio.h> +#endif + +#include "rand_source.h" + + +/* + * global dev_rand_fdes is file descriptor for /dev/random + * + * This variable is also used to indicate that the random source has + * been initialized. When this variable is set to the value of the + * #define RAND_SOURCE_NOT_READY, it indicates that the random source + * is not ready to be used. The value of the #define + * RAND_SOURCE_READY is for use whenever that variable is used as an + * indicator of the state of the random source, but not as a file + * descriptor. + */ + +#define RAND_SOURCE_NOT_READY (-1) +#define RAND_SOURCE_READY (17) + +static int dev_random_fdes = RAND_SOURCE_NOT_READY; + + +err_status_t +rand_source_init(void) { + if (dev_random_fdes >= 0) { + /* already open */ + return err_status_ok; + } +#ifdef DEV_URANDOM + /* open random source for reading */ + dev_random_fdes = open(DEV_URANDOM, O_RDONLY); + if (dev_random_fdes < 0) + return err_status_init_fail; +#elif (_MSC_VER >= 1400) + dev_random_fdes = RAND_SOURCE_READY; +#else + /* no random source available; let the user know */ + fprintf(stderr, "WARNING: no real random source present!\n"); + dev_random_fdes = RAND_SOURCE_READY; +#endif + return err_status_ok; +} + +err_status_t +rand_source_get_octet_string(void *dest, uint32_t len) { + + /* + * read len octets from /dev/random to dest, and + * check return value to make sure enough octets were + * written + */ +#ifdef DEV_URANDOM + if (read(dev_random_fdes, dest, len) != len) + return err_status_fail; +#elif 0 && (_MSC_VER >= 1400) /* disabled rand_s, causing assertion 'rand_s not supported' in vs8 */ + unsigned int *dst = dest; + while (len) + { + unsigned int val = 0; + errno_t err = rand_s(&val); + if (err != 0) + { + return err_status_fail; + } + + *dst++ = val; + len--; + } +#else + /* Generic C-library (rand()) version */ + /* This is a random source of last resort */ + uint8_t *dst = (uint8_t *)dest; + while (len) + { + int val = rand(); + /* rand() returns 0-32767 (ugh) */ + /* Is this a good enough way to get random bytes? + It is if it passes FIPS-140... */ + *dst++ = val & 0xff; + len--; + } +#endif + return err_status_ok; +} + +err_status_t +rand_source_deinit(void) { + if (dev_random_fdes < 0) + return err_status_dealloc_fail; /* well, we haven't really failed, * + * but there is something wrong */ +#ifdef DEV_URANDOM + close(dev_random_fdes); +#endif + dev_random_fdes = RAND_SOURCE_NOT_READY; + + return err_status_ok; +} |