bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 1 | /* |
| 2 | * General purpose random utilities |
| 3 | * |
| 4 | * Based on libuuid code. |
| 5 | * |
| 6 | * This file may be redistributed under the terms of the |
| 7 | * GNU Lesser General Public License. |
| 8 | */ |
| 9 | #include <stdio.h> |
| 10 | #include <unistd.h> |
| 11 | #include <fcntl.h> |
| 12 | #include <stdlib.h> |
| 13 | #include <string.h> |
| 14 | #include <sys/time.h> |
| 15 | |
| 16 | #include <sys/syscall.h> |
| 17 | |
bigbiff | 7b4c7a6 | 2015-01-01 19:44:14 -0500 | [diff] [blame^] | 18 | #include "c.h" |
bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 19 | #include "randutils.h" |
bigbiff | 7b4c7a6 | 2015-01-01 19:44:14 -0500 | [diff] [blame^] | 20 | #include "nls.h" |
bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 21 | |
| 22 | #ifdef HAVE_TLS |
| 23 | #define THREAD_LOCAL static __thread |
| 24 | #else |
| 25 | #define THREAD_LOCAL static |
| 26 | #endif |
| 27 | |
| 28 | #if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48) |
| 29 | #define DO_JRAND_MIX |
| 30 | THREAD_LOCAL unsigned short ul_jrand_seed[3]; |
| 31 | #endif |
| 32 | |
| 33 | int random_get_fd(void) |
| 34 | { |
| 35 | int i, fd; |
| 36 | struct timeval tv; |
| 37 | |
| 38 | gettimeofday(&tv, 0); |
bigbiff | 7b4c7a6 | 2015-01-01 19:44:14 -0500 | [diff] [blame^] | 39 | fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC); |
bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 40 | if (fd == -1) |
bigbiff | 7b4c7a6 | 2015-01-01 19:44:14 -0500 | [diff] [blame^] | 41 | fd = open("/dev/random", O_RDONLY | O_NONBLOCK | O_CLOEXEC); |
bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 42 | if (fd >= 0) { |
| 43 | i = fcntl(fd, F_GETFD); |
| 44 | if (i >= 0) |
| 45 | fcntl(fd, F_SETFD, i | FD_CLOEXEC); |
| 46 | } |
| 47 | srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec); |
| 48 | |
| 49 | #ifdef DO_JRAND_MIX |
| 50 | ul_jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF); |
| 51 | ul_jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF); |
| 52 | ul_jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16; |
| 53 | #endif |
| 54 | /* Crank the random number generator a few times */ |
| 55 | gettimeofday(&tv, 0); |
| 56 | for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--) |
| 57 | rand(); |
| 58 | return fd; |
| 59 | } |
| 60 | |
| 61 | |
| 62 | /* |
| 63 | * Generate a stream of random nbytes into buf. |
| 64 | * Use /dev/urandom if possible, and if not, |
| 65 | * use glibc pseudo-random functions. |
| 66 | */ |
| 67 | void random_get_bytes(void *buf, size_t nbytes) |
| 68 | { |
| 69 | size_t i, n = nbytes; |
| 70 | int fd = random_get_fd(); |
| 71 | int lose_counter = 0; |
| 72 | unsigned char *cp = (unsigned char *) buf; |
| 73 | |
| 74 | if (fd >= 0) { |
| 75 | while (n > 0) { |
| 76 | ssize_t x = read(fd, cp, n); |
| 77 | if (x <= 0) { |
| 78 | if (lose_counter++ > 16) |
| 79 | break; |
| 80 | continue; |
| 81 | } |
| 82 | n -= x; |
| 83 | cp += x; |
| 84 | lose_counter = 0; |
| 85 | } |
| 86 | |
| 87 | close(fd); |
| 88 | } |
| 89 | |
| 90 | /* |
| 91 | * We do this all the time, but this is the only source of |
| 92 | * randomness if /dev/random/urandom is out to lunch. |
| 93 | */ |
| 94 | for (cp = buf, i = 0; i < nbytes; i++) |
| 95 | *cp++ ^= (rand() >> 7) & 0xFF; |
| 96 | |
| 97 | #ifdef DO_JRAND_MIX |
| 98 | { |
| 99 | unsigned short tmp_seed[3]; |
| 100 | |
| 101 | memcpy(tmp_seed, ul_jrand_seed, sizeof(tmp_seed)); |
| 102 | ul_jrand_seed[2] = ul_jrand_seed[2] ^ syscall(__NR_gettid); |
| 103 | for (cp = buf, i = 0; i < nbytes; i++) |
| 104 | *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF; |
| 105 | memcpy(ul_jrand_seed, tmp_seed, |
| 106 | sizeof(ul_jrand_seed)-sizeof(unsigned short)); |
| 107 | } |
| 108 | #endif |
| 109 | |
| 110 | return; |
| 111 | } |
| 112 | |
bigbiff | 7b4c7a6 | 2015-01-01 19:44:14 -0500 | [diff] [blame^] | 113 | |
| 114 | /* |
| 115 | * Tell source of randomness. |
| 116 | */ |
| 117 | const char *random_tell_source(void) |
| 118 | { |
| 119 | size_t i; |
| 120 | static const char *random_sources[] = { |
| 121 | "/dev/urandom", |
| 122 | "/dev/random" |
| 123 | }; |
| 124 | |
| 125 | for (i = 0; i < ARRAY_SIZE(random_sources); i++) { |
| 126 | if (!access(random_sources[i], R_OK)) |
| 127 | return random_sources[i]; |
| 128 | } |
| 129 | |
| 130 | return _("libc pseudo-random functions"); |
| 131 | } |
| 132 | |
bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 133 | #ifdef TEST_PROGRAM |
| 134 | int main(int argc __attribute__ ((__unused__)), |
| 135 | char *argv[] __attribute__ ((__unused__))) |
| 136 | { |
| 137 | unsigned int v, i; |
| 138 | |
| 139 | /* generate and print 10 random numbers */ |
| 140 | for (i = 0; i < 10; i++) { |
| 141 | random_get_bytes(&v, sizeof(v)); |
| 142 | printf("%d\n", v); |
| 143 | } |
| 144 | |
| 145 | return EXIT_SUCCESS; |
| 146 | } |
| 147 | #endif /* TEST_PROGRAM */ |