Add OpenSSH's timingsafe_bcmp() to libkern.

ok djm@, deraadt@

2 files changed, 35 insertions, 1 deletions

diff --git a/sys/lib/libkern/libkern.h b/sys/lib/libkern/libkern.h
index 36655eae4d7..6fd66719779 100644
--- a/sys/lib/libkern/libkern.h
+++ b/sys/lib/libkern/libkern.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: libkern.h,v 1.26 2009/05/24 10:50:34 jsg Exp $	*/
+/*	$OpenBSD: libkern.h,v 1.27 2010/07/20 15:28:44 matthew Exp $	*/
 /*	$NetBSD: libkern.h,v 1.7 1996/03/14 18:52:08 christos Exp $	*/
 
 /*-
@@ -163,5 +163,6 @@ int	 strncasecmp(const char *, const char *, size_t);
 int	 getsn(char *, int);
 char	*strchr(const char *, int);
 char	*strrchr(const char *, int);
+int	 timingsafe_bcmp(const void *, const void *, size_t);
 
 #endif /* __LIBKERN_H__ */
diff --git a/sys/lib/libkern/timingsafe_bcmp.c b/sys/lib/libkern/timingsafe_bcmp.c
new file mode 100644
index 00000000000..8e25a2394de
--- /dev/null
+++ b/sys/lib/libkern/timingsafe_bcmp.c
@@ -0,0 +1,33 @@
+/*	$OpenBSD: timingsafe_bcmp.c,v 1.1 2010/07/20 15:28:44 matthew Exp $	*/
+/*
+ * Copyright (c) 2010 Damien Miller.  All rights reserved.
+ *
+ * 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.
+ */
+
+#if !defined(_KERNEL) && !defined(_STANDALONE)
+#include <string.h>
+#else
+#include <lib/libkern/libkern.h>
+#endif
+
+int
+timingsafe_bcmp(const void *b1, const void *b2, size_t n)
+{
+	const unsigned char *p1 = b1, *p2 = b2;
+	int ret = 0;
+
+	for (; n > 0; n--)
+		ret |= *p1++ ^ *p2++;
+	return (ret != 0);
+}