path: root/main/libasr/00-use-openbsd-res_randomid.patch

diff --git a/configure.ac b/configure.ac
index 10aff04..ec6fadf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,7 +41,7 @@ AC_PATH_PROG([NROFF], [nroff])
 AC_PATH_PROG([MANDOC], [mandoc])
 AC_PROG_YACC
 
-AM_INIT_AUTOMAKE
+AM_INIT_AUTOMAKE([subdir-objects no-dependencies])
 
 LT_INIT
 
@@ -442,6 +442,10 @@ fi
 #l1572 (customized)
 dnl    Checks for library functions. Please keep in alphabetical order
 AC_CHECK_FUNCS([ \
+	arc4random \
+	arc4random_buf \
+	arc4random_stir \
+	arc4random_uniform \
 	asprintf \
 	bcopy \
 	explicit_bzero \
@@ -465,6 +469,13 @@ AC_CHECK_FUNCS([ \
 	vasprintf \
 	vsnprintf \
 ])
+
+AC_CHECK_FUNC([res_randomid],
+	[AC_DEFINE([HAVE_RES_RANDOMID], [1], [Define if res_randomid exists])])
+AM_CONDITIONAL([USE_OPENBSD_RES_RANDOM], [test "x$HAVE_RES_RANDOMID" = "x" ])
+AM_COND_IF([USE_OPENBSD_RES_RANDOM],
+	[AC_CHECK_LIB([crypto], [RAND_bytes], [], [AC_MSG_ERROR([libcrypto not found])])])
+
 #l1685
 
 #l1715
diff --git a/openbsd-compat/NOTES b/openbsd-compat/NOTES
index baa60ec..0eb0710 100644
--- a/openbsd-compat/NOTES
+++ b/openbsd-compat/NOTES
@@ -1,10 +1,12 @@
 List of files and where they come from
 
+arc4random.c		portable openssh
 clock_gettime.c		handmade
 defines.h		portable openssh
 fgetln.c		part of /usr/src/usr.bin/make/util.c
 includes.h		portable openssh
 openbsd-compat.h	portable openssh
+res_random.c		src/lib/libc/net/res_random.c
 strlcat.c		portable openssh
 strlcpy.c		portable openssh
 strtonum.c		portable openssh
diff --git a/openbsd-compat/arc4random.c b/openbsd-compat/arc4random.c
new file mode 100644
index 0000000..ca4434d
--- /dev/null
+++ b/openbsd-compat/arc4random.c
@@ -0,0 +1,296 @@
+/* OPENBSD ORIGINAL: lib/libc/crypto/arc4random.c */
+
+/*	$OpenBSD: arc4random.c,v 1.25 2013/10/01 18:34:57 markus Exp $	*/
+
+/*
+ * Copyright (c) 1996, David Mazieres <dm@uun.org>
+ * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2013, Markus Friedl <markus@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.
+ */
+
+/*
+ * ChaCha based random number generator for OpenBSD.
+ */
+
+#include "includes.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#ifndef HAVE_ARC4RANDOM
+
+#include <openssl/rand.h>
+#include <openssl/err.h>
+
+#define KEYSTREAM_ONLY
+#include "chacha_private.h"
+
+#ifdef __GNUC__
+#define inline __inline
+#else				/* !__GNUC__ */
+#define inline
+#endif				/* !__GNUC__ */
+
+/* OpenSSH isn't multithreaded */
+#define _ARC4_LOCK()
+#define _ARC4_UNLOCK()
+
+#define KEYSZ	32
+#define IVSZ	8
+#define BLOCKSZ	64
+#define RSBUFSZ	(16*BLOCKSZ)
+static int rs_initialized;
+static pid_t rs_stir_pid;
+static chacha_ctx rs;		/* chacha context for random keystream */
+static u_char rs_buf[RSBUFSZ];	/* keystream blocks */
+static size_t rs_have;		/* valid bytes at end of rs_buf */
+static size_t rs_count;		/* bytes till reseed */
+
+static inline void _rs_rekey(u_char *dat, size_t datlen);
+
+static inline void
+_rs_init(u_char *buf, size_t n)
+{
+	if (n < KEYSZ + IVSZ)
+		return;
+	chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
+	chacha_ivsetup(&rs, buf + KEYSZ);
+}
+
+static void
+_rs_stir(void)
+{
+	u_char rnd[KEYSZ + IVSZ];
+
+	if (RAND_bytes(rnd, sizeof(rnd)) <= 0) {
+		fprintf(stderr,
+		    "libasr: Couldn't obtain random bytes (error %ld)",
+		    ERR_get_error());
+		exit(1);
+	}
+
+	if (!rs_initialized) {
+		rs_initialized = 1;
+		_rs_init(rnd, sizeof(rnd));
+	} else
+		_rs_rekey(rnd, sizeof(rnd));
+	memset(rnd, 0, sizeof(rnd));
+
+	/* invalidate rs_buf */
+	rs_have = 0;
+	memset(rs_buf, 0, RSBUFSZ);
+
+	rs_count = 1600000;
+}
+
+static inline void
+_rs_stir_if_needed(size_t len)
+{
+	pid_t pid = getpid();
+
+	if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
+		rs_stir_pid = pid;
+		_rs_stir();
+	} else
+		rs_count -= len;
+}
+
+static inline void
+_rs_rekey(u_char *dat, size_t datlen)
+{
+#ifndef KEYSTREAM_ONLY
+	memset(rs_buf, 0,RSBUFSZ);
+#endif
+	/* fill rs_buf with the keystream */
+	chacha_encrypt_bytes(&rs, rs_buf, rs_buf, RSBUFSZ);
+	/* mix in optional user provided data */
+	if (dat) {
+		size_t i, m;
+
+		m = MIN(datlen, KEYSZ + IVSZ);
+		for (i = 0; i < m; i++)
+			rs_buf[i] ^= dat[i];
+	}
+	/* immediately reinit for backtracking resistance */
+	_rs_init(rs_buf, KEYSZ + IVSZ);
+	memset(rs_buf, 0, KEYSZ + IVSZ);
+	rs_have = RSBUFSZ - KEYSZ - IVSZ;
+}
+
+static inline void
+_rs_random_buf(void *_buf, size_t n)
+{
+	u_char *buf = (u_char *)_buf;
+	size_t m;
+
+	_rs_stir_if_needed(n);
+	while (n > 0) {
+		if (rs_have > 0) {
+			m = MIN(n, rs_have);
+			memcpy(buf, rs_buf + RSBUFSZ - rs_have, m);
+			memset(rs_buf + RSBUFSZ - rs_have, 0, m);
+			buf += m;
+			n -= m;
+			rs_have -= m;
+		}
+		if (rs_have == 0)
+			_rs_rekey(NULL, 0);
+	}
+}
+
+static inline void
+_rs_random_u32(u_int32_t *val)
+{
+	_rs_stir_if_needed(sizeof(*val));
+	if (rs_have < sizeof(*val))
+		_rs_rekey(NULL, 0);
+	memcpy(val, rs_buf + RSBUFSZ - rs_have, sizeof(*val));
+	memset(rs_buf + RSBUFSZ - rs_have, 0, sizeof(*val));
+	rs_have -= sizeof(*val);
+	return;
+}
+
+void
+arc4random_stir(void)
+{
+	_ARC4_LOCK();
+	_rs_stir();
+	_ARC4_UNLOCK();
+}
+
+void
+arc4random_addrandom(u_char *dat, int datlen)
+{
+	int m;
+
+	_ARC4_LOCK();
+	if (!rs_initialized)
+		_rs_stir();
+	while (datlen > 0) {
+		m = MIN(datlen, KEYSZ + IVSZ);
+		_rs_rekey(dat, m);
+		dat += m;
+		datlen -= m;
+	}
+	_ARC4_UNLOCK();
+}
+
+u_int32_t
+arc4random(void)
+{
+	u_int32_t val;
+
+	_ARC4_LOCK();
+	_rs_random_u32(&val);
+	_ARC4_UNLOCK();
+	return val;
+}
+
+/*
+ * If we are providing arc4random, then we can provide a more efficient 
+ * arc4random_buf().
+ */
+# ifndef HAVE_ARC4RANDOM_BUF
+void
+arc4random_buf(void *buf, size_t n)
+{
+	_ARC4_LOCK();
+	_rs_random_buf(buf, n);
+	_ARC4_UNLOCK();
+}
+# endif /* !HAVE_ARC4RANDOM_BUF */
+#endif /* !HAVE_ARC4RANDOM */
+
+/* arc4random_buf() that uses platform arc4random() */
+#if !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM)
+void
+arc4random_buf(void *_buf, size_t n)
+{
+	size_t i;
+	u_int32_t r = 0;
+	char *buf = (char *)_buf;
+
+	for (i = 0; i < n; i++) {
+		if (i % 4 == 0)
+			r = arc4random();
+		buf[i] = r & 0xff;
+		r >>= 8;
+	}
+	explicit_bzero(&r, sizeof(r));
+}
+#endif /* !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM) */
+
+#ifndef HAVE_ARC4RANDOM_UNIFORM
+/*
+ * 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;
+
+	/* 2**32 % x == (2**32 - x) % x */
+	min = -upper_bound % upper_bound;
+
+	/*
+	 * 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 /* !HAVE_ARC4RANDOM_UNIFORM */
+
+#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);
+	exit(0);
+}
+#endif
diff --git a/openbsd-compat/chacha_private.h b/openbsd-compat/chacha_private.h
new file mode 100644
index 0000000..7c3680f
--- /dev/null
+++ b/openbsd-compat/chacha_private.h
@@ -0,0 +1,222 @@
+/*
+chacha-merged.c version 20080118
+D. J. Bernstein
+Public domain.
+*/
+
+/* $OpenBSD: chacha_private.h,v 1.2 2013/10/04 07:02:27 djm Exp $ */
+
+typedef unsigned char u8;
+typedef unsigned int u32;
+
+typedef struct
+{
+  u32 input[16]; /* could be compressed */
+} chacha_ctx;
+
+#define U8C(v) (v##U)
+#define U32C(v) (v##U)
+
+#define U8V(v) ((u8)(v) & U8C(0xFF))
+#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF))
+
+#define ROTL32(v, n) \
+  (U32V((v) << (n)) | ((v) >> (32 - (n))))
+
+#define U8TO32_LITTLE(p) \
+  (((u32)((p)[0])      ) | \
+   ((u32)((p)[1]) <<  8) | \
+   ((u32)((p)[2]) << 16) | \
+   ((u32)((p)[3]) << 24))
+
+#define U32TO8_LITTLE(p, v) \
+  do { \
+    (p)[0] = U8V((v)      ); \
+    (p)[1] = U8V((v) >>  8); \
+    (p)[2] = U8V((v) >> 16); \
+    (p)[3] = U8V((v) >> 24); \
+  } while (0)
+
+#define ROTATE(v,c) (ROTL32(v,c))
+#define XOR(v,w) ((v) ^ (w))
+#define PLUS(v,w) (U32V((v) + (w)))
+#define PLUSONE(v) (PLUS((v),1))
+
+#define QUARTERROUND(a,b,c,d) \
+  a = PLUS(a,b); d = ROTATE(XOR(d,a),16); \
+  c = PLUS(c,d); b = ROTATE(XOR(b,c),12); \
+  a = PLUS(a,b); d = ROTATE(XOR(d,a), 8); \
+  c = PLUS(c,d); b = ROTATE(XOR(b,c), 7);
+
+static const char sigma[16] = "expand 32-byte k";
+static const char tau[16] = "expand 16-byte k";
+
+static void
+chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits,u32 ivbits)
+{
+  const char *constants;
+
+  x->input[4] = U8TO32_LITTLE(k + 0);
+  x->input[5] = U8TO32_LITTLE(k + 4);
+  x->input[6] = U8TO32_LITTLE(k + 8);
+  x->input[7] = U8TO32_LITTLE(k + 12);
+  if (kbits == 256) { /* recommended */
+    k += 16;
+    constants = sigma;
+  } else { /* kbits == 128 */
+    constants = tau;
+  }
+  x->input[8] = U8TO32_LITTLE(k + 0);
+  x->input[9] = U8TO32_LITTLE(k + 4);
+  x->input[10] = U8TO32_LITTLE(k + 8);
+  x->input[11] = U8TO32_LITTLE(k + 12);
+  x->input[0] = U8TO32_LITTLE(constants + 0);
+  x->input[1] = U8TO32_LITTLE(constants + 4);
+  x->input[2] = U8TO32_LITTLE(constants + 8);
+  x->input[3] = U8TO32_LITTLE(constants + 12);
+}
+
+static void
+chacha_ivsetup(chacha_ctx *x,const u8 *iv)
+{
+  x->input[12] = 0;
+  x->input[13] = 0;
+  x->input[14] = U8TO32_LITTLE(iv + 0);
+  x->input[15] = U8TO32_LITTLE(iv + 4);
+}
+
+static void
+chacha_encrypt_bytes(chacha_ctx *x,const u8 *m,u8 *c,u32 bytes)
+{
+  u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
+  u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
+  u8 *ctarget = NULL;
+  u8 tmp[64];
+  u_int i;
+
+  if (!bytes) return;
+
+  j0 = x->input[0];
+  j1 = x->input[1];
+  j2 = x->input[2];
+  j3 = x->input[3];
+  j4 = x->input[4];
+  j5 = x->input[5];
+  j6 = x->input[6];
+  j7 = x->input[7];
+  j8 = x->input[8];
+  j9 = x->input[9];
+  j10 = x->input[10];
+  j11 = x->input[11];
+  j12 = x->input[12];
+  j13 = x->input[13];
+  j14 = x->input[14];
+  j15 = x->input[15];
+
+  for (;;) {
+    if (bytes < 64) {
+      for (i = 0;i < bytes;++i) tmp[i] = m[i];
+      m = tmp;
+      ctarget = c;
+      c = tmp;
+    }
+    x0 = j0;
+    x1 = j1;
+    x2 = j2;
+    x3 = j3;
+    x4 = j4;
+    x5 = j5;
+    x6 = j6;
+    x7 = j7;
+    x8 = j8;
+    x9 = j9;
+    x10 = j10;
+    x11 = j11;
+    x12 = j12;
+    x13 = j13;
+    x14 = j14;
+    x15 = j15;
+    for (i = 20;i > 0;i -= 2) {
+      QUARTERROUND( x0, x4, x8,x12)
+      QUARTERROUND( x1, x5, x9,x13)
+      QUARTERROUND( x2, x6,x10,x14)
+      QUARTERROUND( x3, x7,x11,x15)
+      QUARTERROUND( x0, x5,x10,x15)
+      QUARTERROUND( x1, x6,x11,x12)
+      QUARTERROUND( x2, x7, x8,x13)
+      QUARTERROUND( x3, x4, x9,x14)
+    }
+    x0 = PLUS(x0,j0);
+    x1 = PLUS(x1,j1);
+    x2 = PLUS(x2,j2);
+    x3 = PLUS(x3,j3);
+    x4 = PLUS(x4,j4);
+    x5 = PLUS(x5,j5);
+    x6 = PLUS(x6,j6);
+    x7 = PLUS(x7,j7);
+    x8 = PLUS(x8,j8);
+    x9 = PLUS(x9,j9);
+    x10 = PLUS(x10,j10);
+    x11 = PLUS(x11,j11);
+    x12 = PLUS(x12,j12);
+    x13 = PLUS(x13,j13);
+    x14 = PLUS(x14,j14);
+    x15 = PLUS(x15,j15);
+
+#ifndef KEYSTREAM_ONLY
+    x0 = XOR(x0,U8TO32_LITTLE(m + 0));
+    x1 = XOR(x1,U8TO32_LITTLE(m + 4));
+    x2 = XOR(x2,U8TO32_LITTLE(m + 8));
+    x3 = XOR(x3,U8TO32_LITTLE(m + 12));
+    x4 = XOR(x4,U8TO32_LITTLE(m + 16));
+    x5 = XOR(x5,U8TO32_LITTLE(m + 20));
+    x6 = XOR(x6,U8TO32_LITTLE(m + 24));
+    x7 = XOR(x7,U8TO32_LITTLE(m + 28));
+    x8 = XOR(x8,U8TO32_LITTLE(m + 32));
+    x9 = XOR(x9,U8TO32_LITTLE(m + 36));
+    x10 = XOR(x10,U8TO32_LITTLE(m + 40));
+    x11 = XOR(x11,U8TO32_LITTLE(m + 44));
+    x12 = XOR(x12,U8TO32_LITTLE(m + 48));
+    x13 = XOR(x13,U8TO32_LITTLE(m + 52));
+    x14 = XOR(x14,U8TO32_LITTLE(m + 56));
+    x15 = XOR(x15,U8TO32_LITTLE(m + 60));
+#endif
+
+    j12 = PLUSONE(j12);
+    if (!j12) {
+      j13 = PLUSONE(j13);
+      /* stopping at 2^70 bytes per nonce is user's responsibility */
+    }
+
+    U32TO8_LITTLE(c + 0,x0);
+    U32TO8_LITTLE(c + 4,x1);
+    U32TO8_LITTLE(c + 8,x2);
+    U32TO8_LITTLE(c + 12,x3);
+    U32TO8_LITTLE(c + 16,x4);
+    U32TO8_LITTLE(c + 20,x5);
+    U32TO8_LITTLE(c + 24,x6);
+    U32TO8_LITTLE(c + 28,x7);
+    U32TO8_LITTLE(c + 32,x8);
+    U32TO8_LITTLE(c + 36,x9);
+    U32TO8_LITTLE(c + 40,x10);
+    U32TO8_LITTLE(c + 44,x11);
+    U32TO8_LITTLE(c + 48,x12);
+    U32TO8_LITTLE(c + 52,x13);
+    U32TO8_LITTLE(c + 56,x14);
+    U32TO8_LITTLE(c + 60,x15);
+
+    if (bytes <= 64) {
+      if (bytes < 64) {
+        for (i = 0;i < bytes;++i) ctarget[i] = c[i];
+      }
+      x->input[12] = j12;
+      x->input[13] = j13;
+      return;
+    }
+    bytes -= 64;
+    c += 64;
+#ifndef KEYSTREAM_ONLY
+    m += 64;
+#endif
+  }
+}
diff --git a/openbsd-compat/defines.h b/openbsd-compat/defines.h
index da7a42c..b734c90 100644
--- a/openbsd-compat/defines.h
+++ b/openbsd-compat/defines.h
@@ -745,6 +745,15 @@ struct winsize {
 #define INET6_ADDRSTRLEN 46
 #endif
 
+/*
+ * Platforms that have arc4random_uniform() and not arc4random_stir()
+ * shouldn't need the latter.
+ */
+#if defined(HAVE_ARC4RANDOM) && defined(HAVE_ARC4RANDOM_UNIFORM) && \
+    !defined(HAVE_ARC4RANDOM_STIR)
+# define arc4random_stir()
+#endif
+
 #ifndef HAVE_VA_COPY
 # ifdef HAVE___VA_COPY
 #  define va_copy(dest, src) __va_copy(dest, src)
@@ -823,7 +832,7 @@ struct winsize {
 #endif
 
 #ifndef NETDB_SUCCESS
-# define NETDB_SUCCESS -1
+# define NETDB_SUCCESS 0
 #endif
 
 /* end of chl */
diff --git a/openbsd-compat/openbsd-compat.h b/openbsd-compat/openbsd-compat.h
index c30591c..7baccc8 100644
--- a/openbsd-compat/openbsd-compat.h
+++ b/openbsd-compat/openbsd-compat.h
@@ -63,7 +63,28 @@ char *strsep(char **stringp, const char *delim);
 
 #ifndef HAVE_ASPRINTF
 int asprintf(char **, const char *, ...);
-#endif 
+#endif
+
+#ifdef HAVE_ARC4RANDOM
+# ifndef HAVE_ARC4RANDOM_STIR
+#  define arc4random_stir()
+# endif
+#else
+unsigned int arc4random(void);
+void arc4random_stir(void);
+#endif /* !HAVE_ARC4RANDOM */
+
+#ifndef HAVE_ARC4RANDOM_BUF
+void arc4random_buf(void *, size_t);
+#endif
+
+#ifndef HAVE_ARC4RANDOM_UNIFORM
+u_int32_t arc4random_uniform(u_int32_t);
+#endif
+
+#ifndef HAVE_RES_RANDOMID
+u_int res_randomid(void);
+#endif
 
 /* #include <sys/types.h> XXX needed? For size_t */
 
diff --git a/openbsd-compat/res_random.c b/openbsd-compat/res_random.c
new file mode 100644
index 0000000..7910019
--- /dev/null
+++ b/openbsd-compat/res_random.c
@@ -0,0 +1,283 @@
+/* $OpenBSD: res_random.c,v 1.22 2015/06/04 19:26:39 eric Exp $ */
+
+/*
+ * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
+ * Copyright 2008 Damien Miller <djm@openbsd.org>
+ * All rights reserved.
+ *
+ * Theo de Raadt <deraadt@openbsd.org> came up with the idea of using
+ * such a mathematical system to generate more random (yet non-repeating)
+ * ids to solve the resolver/named problem.  But Niels designed the
+ * actual system based on the constraints.
+ *
+ * Later modified by Damien Miller to wrap the LCG output in a 15-bit
+ * permutation generator based on a Luby-Rackoff block cipher. This
+ * ensures the output is non-repeating and preserves the MSB twiddle
+ * trick, but makes it more resistant to LCG prediction.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
+ */
+
+/* 
+ * seed = random 15bit
+ * n = prime, g0 = generator to n,
+ * j = random so that gcd(j,n-1) == 1
+ * g = g0^j mod n will be a generator again.
+ *
+ * X[0] = random seed.
+ * X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator
+ * with a = 7^(even random) mod m, 
+ *      b = random with gcd(b,m) == 1
+ *      m = 31104 and a maximal period of m-1.
+ *
+ * The transaction id is determined by:
+ * id[n] = seed xor (g^X[n] mod n)
+ *
+ * Effectivly the id is restricted to the lower 15 bits, thus
+ * yielding two different cycles by toggling the msb on and off.
+ * This avoids reuse issues caused by reseeding.
+ *
+ * The output of this generator is then randomly permuted though a
+ * custom 15 bit Luby-Rackoff block cipher.
+ */
+
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/time.h>
+#include <resolv.h>
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include "thread_private.h"
+
+#include "openbsd-compat.h"
+
+#define RU_OUT  	180	/* Time after wich will be reseeded */
+#define RU_MAX		30000	/* Uniq cycle, avoid blackjack prediction */
+#define RU_GEN		2	/* Starting generator */
+#define RU_N		32749	/* RU_N-1 = 2*2*3*2729 */
+#define RU_AGEN		7	/* determine ru_a as RU_AGEN^(2*rand) */
+#define RU_M		31104	/* RU_M = 2^7*3^5 - don't change */
+#define RU_ROUNDS	11	/* Number of rounds for permute (odd) */
+
+struct prf_ctx {
+	/* PRF lookup table for odd rounds (7 bits input to 8 bits output) */
+	u_char prf7[(RU_ROUNDS / 2) * (1 << 7)];
+
+	/* PRF lookup table for even rounds (8 bits input to 7 bits output) */
+	u_char prf8[((RU_ROUNDS + 1) / 2) * (1 << 8)];
+};
+
+#define PFAC_N 3
+static const u_int16_t pfacts[PFAC_N] = {
+	2, 
+	3,
+	2729
+};
+
+static u_int16_t ru_x;
+static u_int16_t ru_seed, ru_seed2;
+static u_int16_t ru_a, ru_b;
+static u_int16_t ru_g;
+static u_int16_t ru_counter = 0;
+static u_int16_t ru_msb = 0;
+static struct prf_ctx *ru_prf = NULL;
+static time_t ru_reseed;
+static pid_t ru_pid;
+
+static u_int16_t pmod(u_int16_t, u_int16_t, u_int16_t);
+static void res_initid(void);
+
+/*
+ * Do a fast modular exponation, returned value will be in the range
+ * of 0 - (mod-1)
+ */
+static u_int16_t
+pmod(u_int16_t gen, u_int16_t exp, u_int16_t mod)
+{
+	u_int16_t s, t, u;
+
+	s = 1;
+	t = gen;
+	u = exp;
+
+	while (u) {
+		if (u & 1)
+			s = (s * t) % mod;
+		u >>= 1;
+		t = (t * t) % mod;
+	}
+	return (s);
+}
+
+/*
+ * 15-bit permutation based on Luby-Rackoff block cipher
+ */
+static u_int
+permute15(u_int in)
+{
+	int i;
+	u_int left, right, tmp;
+
+	if (ru_prf == NULL)
+		return in;
+
+	left = (in >> 8) & 0x7f;
+	right = in & 0xff;
+
+	/*
+	 * Each round swaps the width of left and right. Even rounds have
+	 * a 7-bit left, odd rounds have an 8-bit left.	Since this uses an
+	 * odd number of rounds, left is always 8 bits wide at the end.
+	 */
+	for (i = 0; i < RU_ROUNDS; i++) {
+		if ((i & 1) == 0)
+			tmp = ru_prf->prf8[(i << (8 - 1)) | right] & 0x7f;
+		else
+			tmp = ru_prf->prf7[((i - 1) << (7 - 1)) | right];
+		tmp ^= left;
+		left = right;
+		right = tmp;
+	}
+
+	return (right << 8) | left;
+}
+
+/* 
+ * Initializes the seed and chooses a suitable generator. Also toggles 
+ * the msb flag. The msb flag is used to generate two distinct
+ * cycles of random numbers and thus avoiding reuse of ids.
+ *
+ * This function is called from res_randomid() when needed, an 
+ * application does not have to worry about it.
+ */
+static void 
+res_initid(void)
+{
+	u_int16_t j, i;
+	u_int32_t tmp;
+	int noprime = 1;
+	struct timespec ts;
+
+	ru_x = arc4random_uniform(RU_M);
+
+	/* 15 bits of random seed */
+	tmp = arc4random();
+	ru_seed = (tmp >> 16) & 0x7FFF;
+	ru_seed2 = tmp & 0x7FFF;
+
+	/* Determine the LCG we use */
+	tmp = arc4random();
+	ru_b = (tmp & 0xfffe) | 1;
+	ru_a = pmod(RU_AGEN, (tmp >> 16) & 0xfffe, RU_M);
+	while (ru_b % 3 == 0)
+		ru_b += 2;
+	
+	j = arc4random_uniform(RU_N);
+
+	/* 
+	 * Do a fast gcd(j,RU_N-1), so we can find a j with
+	 * gcd(j, RU_N-1) == 1, giving a new generator for
+	 * RU_GEN^j mod RU_N
+	 */
+
+	while (noprime) {
+		for (i = 0; i < PFAC_N; i++)
+			if (j % pfacts[i] == 0)
+				break;
+
+		if (i >= PFAC_N)
+			noprime = 0;
+		else 
+			j = (j + 1) % RU_N;
+	}
+
+	ru_g = pmod(RU_GEN, j, RU_N);
+	ru_counter = 0;
+
+	/* Initialise PRF for Luby-Rackoff permutation */
+	if (ru_prf == NULL)
+		ru_prf = malloc(sizeof(*ru_prf));
+	if (ru_prf != NULL)
+		arc4random_buf(ru_prf, sizeof(*ru_prf));
+
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	ru_reseed = ts.tv_sec + RU_OUT;
+	ru_msb = ru_msb == 0x8000 ? 0 : 0x8000; 
+}
+
+u_int
+res_randomid(void)
+{
+	struct timespec ts;
+	pid_t pid;
+	u_int r;
+	_THREAD_PRIVATE_MUTEX(random);
+
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	pid = getpid();
+
+	_THREAD_PRIVATE_MUTEX_LOCK(random);
+
+	if (ru_counter >= RU_MAX || ts.tv_sec > ru_reseed || pid != ru_pid) {
+		res_initid();
+		ru_pid = pid;
+	}
+
+	/* Linear Congruential Generator */
+	ru_x = (ru_a * ru_x + ru_b) % RU_M;
+	ru_counter++;
+
+	r = permute15(ru_seed ^ pmod(ru_g, ru_seed2 + ru_x, RU_N)) | ru_msb;
+
+	_THREAD_PRIVATE_MUTEX_UNLOCK(random);
+
+	return (r);
+}
+
+#if 0
+int
+main(int argc, char **argv)
+{
+	int i, n;
+	u_int16_t wert;
+
+	res_initid();
+
+	printf("Generator: %u\n", ru_g);
+	printf("Seed: %u\n", ru_seed);
+	printf("Reseed at %ld\n", ru_reseed);
+	printf("Ru_X: %u\n", ru_x);
+	printf("Ru_A: %u\n", ru_a);
+	printf("Ru_B: %u\n", ru_b);
+
+	n = argc > 1 ? atoi(argv[1]) : 60001;
+	for (i=0;i<n;i++) {
+		wert = res_randomid();
+		printf("%u\n", wert);
+	}
+	return 0;
+}
+#endif
+
diff --git a/src/Makefile.am b/src/Makefile.am
index 2e2e40d..75353d4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -12,6 +12,11 @@ libasr_la_SOURCES +=	$(top_srcdir)/openbsd-compat/strlcpy.c
 libasr_la_SOURCES +=	$(top_srcdir)/openbsd-compat/strsep.c
 libasr_la_SOURCES +=	$(top_srcdir)/openbsd-compat/strtonum.c
 
+if USE_OPENBSD_RES_RANDOM
+libasr_la_SOURCES +=	$(top_srcdir)/openbsd-compat/arc4random.c
+libasr_la_SOURCES +=	$(top_srcdir)/openbsd-compat/res_random.c
+endif
+
 include_HEADERS =	asr.h
 
 libasr_la_CPPFLAGS =	-I$(top_srcdir)/src -I$(top_srcdir)/openbsd-compat