Squashed 'third_party/libevent/' content from commit d8ceae8
Change-Id: I84e1b23561eb225b9f288717b028e6bc9e5a27e1
git-subtree-dir: third_party/libevent
git-subtree-split: d8ceae81b83f3d0a56e2f41d4c429b2702a8e302
diff --git a/arc4random.c b/arc4random.c
new file mode 100644
index 0000000..3977339
--- /dev/null
+++ b/arc4random.c
@@ -0,0 +1,555 @@
+/* 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
+ * Copyright (c) 2010-2012 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));
+ evutil_memclear_(buf, sizeof(buf));
+ arc4_seeded_ok = 1;
+ return 0;
+}
+#endif
+
+#if defined(_EVENT_HAVE_SYS_SYSCTL_H) && defined(_EVENT_HAVE_SYSCTL)
+#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));
+ evutil_memclear_(buf, 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));
+ evutil_memclear_(buf, 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 = evutil_open_closeonexec("/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;
+ }
+ evutil_memclear_(entropy, sizeof(entropy));
+ evutil_memclear_(buf, sizeof(buf));
+ arc4_seeded_ok = 1;
+ return 0;
+}
+#endif
+
+#ifndef WIN32
+#define TRY_SEED_URANDOM
+static char *arc4random_urandom_filename = NULL;
+
+static int arc4_seed_urandom_helper_(const char *fname)
+{
+ unsigned char buf[ADD_ENTROPY];
+ int fd;
+ size_t n;
+
+ fd = evutil_open_closeonexec(fname, O_RDONLY, 0);
+ if (fd<0)
+ return -1;
+ n = read_all(fd, buf, sizeof(buf));
+ close(fd);
+ if (n != sizeof(buf))
+ return -1;
+ arc4_addrandom(buf, sizeof(buf));
+ evutil_memclear_(buf, sizeof(buf));
+ arc4_seeded_ok = 1;
+ return 0;
+}
+
+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
+ };
+ int i;
+ if (arc4random_urandom_filename)
+ return arc4_seed_urandom_helper_(arc4random_urandom_filename);
+
+ for (i = 0; filenames[i]; ++i) {
+ if (arc4_seed_urandom_helper_(filenames[i]) == 0) {
+ 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 (arc4random_urandom_filename == NULL &&
+ 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