+++ /dev/null
-/* Portable arc4random.c based on arc4random.c from OpenBSD.
- * Portable version by Chris Davis, adapted for Libevent by Nick Mathewson
- * Copyright (c) 2010 Chris Davis, Niels Provos, and Nick Mathewson
- *
- * Note that in Libevent, this file isn't compiled directly. Instead,
- * it's included from evutil_rand.c
- */
-
-/*
- * Copyright (c) 1996, David Mazieres <dm@uun.org>
- * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-/*
- * Arc4 random number generator for OpenBSD.
- *
- * This code is derived from section 17.1 of Applied Cryptography,
- * second edition, which describes a stream cipher allegedly
- * compatible with RSA Labs "RC4" cipher (the actual description of
- * which is a trade secret). The same algorithm is used as a stream
- * cipher called "arcfour" in Tatu Ylonen's ssh package.
- *
- * Here the stream cipher has been modified always to include the time
- * when initializing the state. That makes it impossible to
- * regenerate the same random sequence twice, so this can't be used
- * for encryption, but will generate good random numbers.
- *
- * RC4 is a registered trademark of RSA Laboratories.
- */
-
-#ifndef ARC4RANDOM_EXPORT
-#define ARC4RANDOM_EXPORT
-#endif
-
-#ifndef ARC4RANDOM_UINT32
-#define ARC4RANDOM_UINT32 uint32_t
-#endif
-
-#ifndef ARC4RANDOM_NO_INCLUDES
-#ifdef WIN32
-#include <wincrypt.h>
-#include <process.h>
-#else
-#include <fcntl.h>
-#include <unistd.h>
-#include <sys/param.h>
-#include <sys/time.h>
-#ifdef _EVENT_HAVE_SYS_SYSCTL_H
-#include <sys/sysctl.h>
-#endif
-#endif
-#include <limits.h>
-#include <stdlib.h>
-#include <string.h>
-#endif
-
-/* Add platform entropy 32 bytes (256 bits) at a time. */
-#define ADD_ENTROPY 32
-
-/* Re-seed from the platform RNG after generating this many bytes. */
-#define BYTES_BEFORE_RESEED 1600000
-
-struct arc4_stream {
- unsigned char i;
- unsigned char j;
- unsigned char s[256];
-};
-
-#ifdef WIN32
-#define getpid _getpid
-#define pid_t int
-#endif
-
-static int rs_initialized;
-static struct arc4_stream rs;
-static pid_t arc4_stir_pid;
-static int arc4_count;
-static int arc4_seeded_ok;
-
-static inline unsigned char arc4_getbyte(void);
-
-static inline void
-arc4_init(void)
-{
- int n;
-
- for (n = 0; n < 256; n++)
- rs.s[n] = n;
- rs.i = 0;
- rs.j = 0;
-}
-
-static inline void
-arc4_addrandom(const unsigned char *dat, int datlen)
-{
- int n;
- unsigned char si;
-
- rs.i--;
- for (n = 0; n < 256; n++) {
- rs.i = (rs.i + 1);
- si = rs.s[rs.i];
- rs.j = (rs.j + si + dat[n % datlen]);
- rs.s[rs.i] = rs.s[rs.j];
- rs.s[rs.j] = si;
- }
- rs.j = rs.i;
-}
-
-#ifndef WIN32
-static ssize_t
-read_all(int fd, unsigned char *buf, size_t count)
-{
- size_t numread = 0;
- ssize_t result;
-
- while (numread < count) {
- result = read(fd, buf+numread, count-numread);
- if (result<0)
- return -1;
- else if (result == 0)
- break;
- numread += result;
- }
-
- return (ssize_t)numread;
-}
-#endif
-
-#ifdef WIN32
-#define TRY_SEED_WIN32
-static int
-arc4_seed_win32(void)
-{
- /* This is adapted from Tor's crypto_seed_rng() */
- static int provider_set = 0;
- static HCRYPTPROV provider;
- unsigned char buf[ADD_ENTROPY];
-
- if (!provider_set) {
- if (!CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
- CRYPT_VERIFYCONTEXT)) {
- if (GetLastError() != (DWORD)NTE_BAD_KEYSET)
- return -1;
- }
- provider_set = 1;
- }
- if (!CryptGenRandom(provider, sizeof(buf), buf))
- return -1;
- arc4_addrandom(buf, sizeof(buf));
- memset(buf, 0, sizeof(buf));
- arc4_seeded_ok = 1;
- return 0;
-}
-#endif
-
-#if defined(_EVENT_HAVE_SYS_SYSCTL_H)
-#if _EVENT_HAVE_DECL_CTL_KERN && _EVENT_HAVE_DECL_KERN_RANDOM && _EVENT_HAVE_DECL_RANDOM_UUID
-#define TRY_SEED_SYSCTL_LINUX
-static int
-arc4_seed_sysctl_linux(void)
-{
- /* Based on code by William Ahern, this function tries to use the
- * RANDOM_UUID sysctl to get entropy from the kernel. This can work
- * even if /dev/urandom is inaccessible for some reason (e.g., we're
- * running in a chroot). */
- int mib[] = { CTL_KERN, KERN_RANDOM, RANDOM_UUID };
- unsigned char buf[ADD_ENTROPY];
- size_t len, n;
- unsigned i;
- int any_set;
-
- memset(buf, 0, sizeof(buf));
-
- for (len = 0; len < sizeof(buf); len += n) {
- n = sizeof(buf) - len;
-
- if (0 != sysctl(mib, 3, &buf[len], &n, NULL, 0))
- return -1;
- }
- /* make sure that the buffer actually got set. */
- for (i=0,any_set=0; i<sizeof(buf); ++i) {
- any_set |= buf[i];
- }
- if (!any_set)
- return -1;
-
- arc4_addrandom(buf, sizeof(buf));
- memset(buf, 0, sizeof(buf));
- arc4_seeded_ok = 1;
- return 0;
-}
-#endif
-
-#if _EVENT_HAVE_DECL_CTL_KERN && _EVENT_HAVE_DECL_KERN_ARND
-#define TRY_SEED_SYSCTL_BSD
-static int
-arc4_seed_sysctl_bsd(void)
-{
- /* Based on code from William Ahern and from OpenBSD, this function
- * tries to use the KERN_ARND syscall to get entropy from the kernel.
- * This can work even if /dev/urandom is inaccessible for some reason
- * (e.g., we're running in a chroot). */
- int mib[] = { CTL_KERN, KERN_ARND };
- unsigned char buf[ADD_ENTROPY];
- size_t len, n;
- int i, any_set;
-
- memset(buf, 0, sizeof(buf));
-
- len = sizeof(buf);
- if (sysctl(mib, 2, buf, &len, NULL, 0) == -1) {
- for (len = 0; len < sizeof(buf); len += sizeof(unsigned)) {
- n = sizeof(unsigned);
- if (n + len > sizeof(buf))
- n = len - sizeof(buf);
- if (sysctl(mib, 2, &buf[len], &n, NULL, 0) == -1)
- return -1;
- }
- }
- /* make sure that the buffer actually got set. */
- for (i=any_set=0; i<sizeof(buf); ++i) {
- any_set |= buf[i];
- }
- if (!any_set)
- return -1;
-
- arc4_addrandom(buf, sizeof(buf));
- memset(buf, 0, sizeof(buf));
- arc4_seeded_ok = 1;
- return 0;
-}
-#endif
-#endif /* defined(_EVENT_HAVE_SYS_SYSCTL_H) */
-
-#ifdef __linux__
-#define TRY_SEED_PROC_SYS_KERNEL_RANDOM_UUID
-static int
-arc4_seed_proc_sys_kernel_random_uuid(void)
-{
- /* Occasionally, somebody will make /proc/sys accessible in a chroot,
- * but not /dev/urandom. Let's try /proc/sys/kernel/random/uuid.
- * Its format is stupid, so we need to decode it from hex.
- */
- int fd;
- char buf[128];
- unsigned char entropy[64];
- int bytes, n, i, nybbles;
- for (bytes = 0; bytes<ADD_ENTROPY; ) {
- fd = open("/proc/sys/kernel/random/uuid", O_RDONLY, 0);
- if (fd < 0)
- return -1;
- n = read(fd, buf, sizeof(buf));
- close(fd);
- if (n<=0)
- return -1;
- memset(entropy, 0, sizeof(entropy));
- for (i=nybbles=0; i<n; ++i) {
- if (EVUTIL_ISXDIGIT(buf[i])) {
- int nyb = evutil_hex_char_to_int(buf[i]);
- if (nybbles & 1) {
- entropy[nybbles/2] |= nyb;
- } else {
- entropy[nybbles/2] |= nyb<<4;
- }
- ++nybbles;
- }
- }
- if (nybbles < 2)
- return -1;
- arc4_addrandom(entropy, nybbles/2);
- bytes += nybbles/2;
- }
- memset(entropy, 0, sizeof(entropy));
- memset(buf, 0, sizeof(buf));
- return 0;
-}
-#endif
-
-#ifndef WIN32
-#define TRY_SEED_URANDOM
-static int
-arc4_seed_urandom(void)
-{
- /* This is adapted from Tor's crypto_seed_rng() */
- static const char *filenames[] = {
- "/dev/srandom", "/dev/urandom", "/dev/random", NULL
- };
- unsigned char buf[ADD_ENTROPY];
- int fd, i;
- size_t n;
-
- for (i = 0; filenames[i]; ++i) {
- fd = open(filenames[i], O_RDONLY, 0);
- if (fd<0)
- continue;
- n = read_all(fd, buf, sizeof(buf));
- close(fd);
- if (n != sizeof(buf))
- return -1;
- arc4_addrandom(buf, sizeof(buf));
- memset(buf, 0, sizeof(buf));
- arc4_seeded_ok = 1;
- return 0;
- }
-
- return -1;
-}
-#endif
-
-static int
-arc4_seed(void)
-{
- int ok = 0;
- /* We try every method that might work, and don't give up even if one
- * does seem to work. There's no real harm in over-seeding, and if
- * one of these sources turns out to be broken, that would be bad. */
-#ifdef TRY_SEED_WIN32
- if (0 == arc4_seed_win32())
- ok = 1;
-#endif
-#ifdef TRY_SEED_URANDOM
- if (0 == arc4_seed_urandom())
- ok = 1;
-#endif
-#ifdef TRY_SEED_PROC_SYS_KERNEL_RANDOM_UUID
- if (0 == arc4_seed_proc_sys_kernel_random_uuid())
- ok = 1;
-#endif
-#ifdef TRY_SEED_SYSCTL_LINUX
- /* Apparently Linux is deprecating sysctl, and spewing warning
- * messages when you try to use it. */
- if (!ok && 0 == arc4_seed_sysctl_linux())
- ok = 1;
-#endif
-#ifdef TRY_SEED_SYSCTL_BSD
- if (0 == arc4_seed_sysctl_bsd())
- ok = 1;
-#endif
- return ok ? 0 : -1;
-}
-
-static int
-arc4_stir(void)
-{
- int i;
-
- if (!rs_initialized) {
- arc4_init();
- rs_initialized = 1;
- }
-
- arc4_seed();
- if (!arc4_seeded_ok)
- return -1;
-
- /*
- * Discard early keystream, as per recommendations in
- * "Weaknesses in the Key Scheduling Algorithm of RC4" by
- * Scott Fluhrer, Itsik Mantin, and Adi Shamir.
- * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
- *
- * Ilya Mironov's "(Not So) Random Shuffles of RC4" suggests that
- * we drop at least 2*256 bytes, with 12*256 as a conservative
- * value.
- *
- * RFC4345 says to drop 6*256.
- *
- * At least some versions of this code drop 4*256, in a mistaken
- * belief that "words" in the Fluhrer/Mantin/Shamir paper refers
- * to processor words.
- *
- * We add another sect to the cargo cult, and choose 12*256.
- */
- for (i = 0; i < 12*256; i++)
- (void)arc4_getbyte();
- arc4_count = BYTES_BEFORE_RESEED;
-
- return 0;
-}
-
-
-static void
-arc4_stir_if_needed(void)
-{
- pid_t pid = getpid();
-
- if (arc4_count <= 0 || !rs_initialized || arc4_stir_pid != pid)
- {
- arc4_stir_pid = pid;
- arc4_stir();
- }
-}
-
-static inline unsigned char
-arc4_getbyte(void)
-{
- unsigned char si, sj;
-
- rs.i = (rs.i + 1);
- si = rs.s[rs.i];
- rs.j = (rs.j + si);
- sj = rs.s[rs.j];
- rs.s[rs.i] = sj;
- rs.s[rs.j] = si;
- return (rs.s[(si + sj) & 0xff]);
-}
-
-static inline unsigned int
-arc4_getword(void)
-{
- unsigned int val;
-
- val = arc4_getbyte() << 24;
- val |= arc4_getbyte() << 16;
- val |= arc4_getbyte() << 8;
- val |= arc4_getbyte();
-
- return val;
-}
-
-#ifndef ARC4RANDOM_NOSTIR
-ARC4RANDOM_EXPORT int
-arc4random_stir(void)
-{
- int val;
- _ARC4_LOCK();
- val = arc4_stir();
- _ARC4_UNLOCK();
- return val;
-}
-#endif
-
-#ifndef ARC4RANDOM_NOADDRANDOM
-ARC4RANDOM_EXPORT void
-arc4random_addrandom(const unsigned char *dat, int datlen)
-{
- int j;
- _ARC4_LOCK();
- if (!rs_initialized)
- arc4_stir();
- for (j = 0; j < datlen; j += 256) {
- /* arc4_addrandom() ignores all but the first 256 bytes of
- * its input. We want to make sure to look at ALL the
- * data in 'dat', just in case the user is doing something
- * crazy like passing us all the files in /var/log. */
- arc4_addrandom(dat + j, datlen - j);
- }
- _ARC4_UNLOCK();
-}
-#endif
-
-#ifndef ARC4RANDOM_NORANDOM
-ARC4RANDOM_EXPORT ARC4RANDOM_UINT32
-arc4random(void)
-{
- ARC4RANDOM_UINT32 val;
- _ARC4_LOCK();
- arc4_count -= 4;
- arc4_stir_if_needed();
- val = arc4_getword();
- _ARC4_UNLOCK();
- return val;
-}
-#endif
-
-ARC4RANDOM_EXPORT void
-arc4random_buf(void *_buf, size_t n)
-{
- unsigned char *buf = _buf;
- _ARC4_LOCK();
- arc4_stir_if_needed();
- while (n--) {
- if (--arc4_count <= 0)
- arc4_stir();
- buf[n] = arc4_getbyte();
- }
- _ARC4_UNLOCK();
-}
-
-#ifndef ARC4RANDOM_NOUNIFORM
-/*
- * Calculate a uniformly distributed random number less than upper_bound
- * avoiding "modulo bias".
- *
- * Uniformity is achieved by generating new random numbers until the one
- * returned is outside the range [0, 2**32 % upper_bound). This
- * guarantees the selected random number will be inside
- * [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound)
- * after reduction modulo upper_bound.
- */
-ARC4RANDOM_EXPORT unsigned int
-arc4random_uniform(unsigned int upper_bound)
-{
- ARC4RANDOM_UINT32 r, min;
-
- if (upper_bound < 2)
- return 0;
-
-#if (UINT_MAX > 0xffffffffUL)
- min = 0x100000000UL % upper_bound;
-#else
- /* Calculate (2**32 % upper_bound) avoiding 64-bit math */
- if (upper_bound > 0x80000000)
- min = 1 + ~upper_bound; /* 2**32 - upper_bound */
- else {
- /* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
- min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
- }
-#endif
-
- /*
- * This could theoretically loop forever but each retry has
- * p > 0.5 (worst case, usually far better) of selecting a
- * number inside the range we need, so it should rarely need
- * to re-roll.
- */
- for (;;) {
- r = arc4random();
- if (r >= min)
- break;
- }
-
- return r % upper_bound;
-}
-#endif
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