1 files changed, 259 insertions, 0 deletions

diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
new file mode 100644
index 0000000000..e921e4b7c7
--- /dev/null
+++ b/src/lib/libc/crypt/arc4random.c
@@ -0,0 +1,259 @@
+/*      $OpenBSD: arc4random.c,v 1.20 2008/10/03 18:46:04 otto Exp $    */
+
+/*
+ * 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.
+ */
+
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/sysctl.h>
+#include "thread_private.h"
+
+#ifdef __GNUC__
+#define inline __inline
+#else                           /* !__GNUC__ */
+#define inline
+#endif                          /* !__GNUC__ */
+
+struct arc4_stream {
+        u_int8_t i;
+        u_int8_t j;
+        u_int8_t s[256];
+};
+
+static int rs_initialized;
+static struct arc4_stream rs;
+static pid_t arc4_stir_pid;
+static int arc4_count;
+
+static inline u_int8_t 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(u_char *dat, int datlen)
+{
+        int     n;
+        u_int8_t 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;
+}
+
+static void
+arc4_stir(void)
+{
+        int     i, mib[2];
+        size_t  len;
+        u_char rnd[128];
+
+        if (!rs_initialized) {
+                arc4_init();
+                rs_initialized = 1;
+        }
+
+        mib[0] = CTL_KERN;
+        mib[1] = KERN_ARND;
+
+        len = sizeof(rnd);
+        sysctl(mib, 2, rnd, &len, NULL, 0);
+
+        arc4_stir_pid = getpid();
+        arc4_addrandom(rnd, sizeof(rnd));
+
+        /*
+         * Discard early keystream, as per recommendations in:
+         * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
+         */
+        for (i = 0; i < 256; i++)
+                (void)arc4_getbyte();
+        arc4_count = 1600000;
+}
+
+static inline u_int8_t
+arc4_getbyte(void)
+{
+        u_int8_t 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 u_int32_t
+arc4_getword(void)
+{
+        u_int32_t val;
+        val = arc4_getbyte() << 24;
+        val |= arc4_getbyte() << 16;
+        val |= arc4_getbyte() << 8;
+        val |= arc4_getbyte();
+        return val;
+}
+
+void
+arc4random_stir(void)
+{
+        _ARC4_LOCK();
+        arc4_stir();
+        _ARC4_UNLOCK();
+}
+
+void
+arc4random_addrandom(u_char *dat, int datlen)
+{
+        _ARC4_LOCK();
+        if (!rs_initialized)
+                arc4_stir();
+        arc4_addrandom(dat, datlen);
+        _ARC4_UNLOCK();
+}
+
+u_int32_t
+arc4random(void)
+{
+        u_int32_t val;
+        _ARC4_LOCK();
+        arc4_count -= 4;
+        if (arc4_count <= 0 || !rs_initialized || arc4_stir_pid != getpid())
+                arc4_stir();
+        val = arc4_getword();
+        _ARC4_UNLOCK();
+        return val;
+}
+
+void
+arc4random_buf(void *_buf, size_t n)
+{
+        u_char *buf = (u_char *)_buf;
+        _ARC4_LOCK();
+        if (!rs_initialized || arc4_stir_pid != getpid())
+                arc4_stir();
+        while (n--) {
+                if (--arc4_count <= 0)
+                        arc4_stir();
+                buf[n] = arc4_getbyte();
+        }
+        _ARC4_UNLOCK();
+}
+
+/*
+ * 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.
+ */
+u_int32_t
+arc4random_uniform(u_int32_t upper_bound)
+{
+        u_int32_t r, min;
+
+        if (upper_bound < 2)
+                return 0;
+
+#if (ULONG_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;
+}
+
+#if 0
+/*-------- Test code for i386 --------*/
+#include <stdio.h>
+#include <machine/pctr.h>
+int
+main(int argc, char **argv)
+{
+        const int iter = 1000000;
+        int     i;
+        pctrval v;
+
+        v = rdtsc();
+        for (i = 0; i < iter; i++)
+                arc4random();
+        v = rdtsc() - v;
+        v /= iter;
+
+        printf("%qd cycles\n", v);
+}
+#endif