From b657b2e6806c09f5eba1f0f4f2e1e3e44bbb0274 Mon Sep 17 00:00:00 2001
From: Love Hornquist Astrand <lha@h5l.org>
Date: Sat, 15 Aug 2009 13:24:52 +0200
Subject: [PATCH] Add constant time version of memcmp

---
 lib/roken/Makefile.am    |  1 +
 lib/roken/ct.c           | 49 ++++++++++++++++++++++++++++++++++++++++
 lib/roken/roken-common.h |  2 ++
 3 files changed, 52 insertions(+)
 create mode 100644 lib/roken/ct.c

diff --git a/lib/roken/Makefile.am b/lib/roken/Makefile.am
index cd64acad0..573e3e7a0 100644
--- a/lib/roken/Makefile.am
+++ b/lib/roken/Makefile.am
@@ -65,6 +65,7 @@ libroken_la_SOURCES =		\
 	bswap.c			\
 	concat.c		\
 	cloexec.c		\
+	ct.c			\
 	dumpdata.c		\
 	environment.c		\
 	eread.c			\
diff --git a/lib/roken/ct.c b/lib/roken/ct.c
new file mode 100644
index 000000000..68f9aacd0
--- /dev/null
+++ b/lib/roken/ct.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2009 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+
+int
+ct_memcmp(const void *p1, const void *p2, size_t len)
+{
+    const unsigned char *s1 = p1, *s2 = p2;
+    size_t i;
+    int r = 0;
+
+    for (i = 0; i < len; i++)
+	if (s1[i] != s2[i] && r == 0)
+	    r = s1[i] - s2[i];
+    return r;
+}
diff --git a/lib/roken/roken-common.h b/lib/roken/roken-common.h
index 1713b6609..ea7dcaade 100644
--- a/lib/roken/roken-common.h
+++ b/lib/roken/roken-common.h
@@ -447,6 +447,8 @@ rk_cloexec(int);
 void ROKEN_LIB_FUNCTION
 rk_cloexec_file(FILE *);
 
+int ROKEN_LIB_FUNCTION
+ct_memcmp(const void *, const void *, size_t);
 
 ROKEN_CPP_END