1 files changed, 104 insertions, 0 deletions
diff --git a/lib/isc/random.c b/lib/isc/random.c
new file mode 100644
index 0000000..0329abd
--- /dev/null
+++ b/lib/isc/random.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (C) 1999-2003  Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC 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.
+ */
+
+/* $Id: random.c,v 1.25 2007/06/19 23:47:17 tbox Exp $ */
+
+/*! \file */
+
+#include <config.h>
+
+#include <stdlib.h>
+#include <time.h>		/* Required for time(). */
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#include <isc/mutex.h>
+#include <isc/once.h>
+#include <isc/random.h>
+#include <isc/string.h>
+#include <isc/util.h>
+
+static isc_once_t once = ISC_ONCE_INIT;
+
+static void
+initialize_rand(void)
+{
+#ifndef HAVE_ARC4RANDOM
+	unsigned int pid = getpid();
+	
+	/*
+	 * The low bits of pid generally change faster.
+	 * Xor them with the high bits of time which change slowly.
+	 */
+	pid = ((pid << 16) & 0xffff0000) | ((pid >> 16) & 0xffff);
+
+	srand(time(NULL) ^ pid);
+#endif
+}
+
+static void
+initialize(void)
+{
+	RUNTIME_CHECK(isc_once_do(&once, initialize_rand) == ISC_R_SUCCESS);
+}
+
+void
+isc_random_seed(isc_uint32_t seed)
+{
+	initialize();
+
+#ifndef HAVE_ARC4RANDOM
+	srand(seed);
+#else
+	arc4random_addrandom((u_char *) &seed, sizeof(isc_uint32_t));
+#endif
+}
+
+void
+isc_random_get(isc_uint32_t *val)
+{
+	REQUIRE(val != NULL);
+
+	initialize();
+
+#ifndef HAVE_ARC4RANDOM
+	/*
+	 * rand()'s lower bits are not random.
+	 * rand()'s upper bit is zero.
+	 */
+	*val = ((rand() >> 4) & 0xffff) | ((rand() << 12) & 0xffff0000);
+#else
+	*val = arc4random();
+#endif
+}
+
+isc_uint32_t
+isc_random_jitter(isc_uint32_t max, isc_uint32_t jitter) {
+	REQUIRE(jitter < max);
+	if (jitter == 0)
+		return (max);
+	else
+#ifndef HAVE_ARC4RANDOM
+		return (max - rand() % jitter);
+#else
+		return (max - arc4random() % jitter);
+#endif
+}