[SCTP]: Use crc32c library for checksum calculations.

The crc32c library used an identical table and algorithm
as SCTP.  Switch to using the library instead of carrying
our own table.  Using crypto layer proved to have too
much overhead compared to using the library directly.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 78 insertions, 0 deletions

diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
new file mode 100644
index 0000000..ba75c67
--- /dev/null
+++ b/include/net/sctp/checksum.h
@@ -0,0 +1,78 @@
+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 International Business Machines, Corp.
+ *
+ * This file is part of the SCTP kernel reference Implementation
+ *
+ * SCTP Checksum functions
+ *
+ * The SCTP reference implementation is free software;
+ * you can redistribute it and/or modify it under the terms of
+ * the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * The SCTP reference implementation is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ *                 ************************
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU CC; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <lksctp-developers@lists.sourceforge.net>
+ *
+ * Or submit a bug report through the following website:
+ *    http://www.sf.net/projects/lksctp
+ *
+ * Written or modified by:
+ *    Dinakaran Joseph
+ *    Jon Grimm <jgrimm@us.ibm.com>
+ *    Sridhar Samudrala <sri@us.ibm.com>
+ *
+ * Rewritten to use libcrc32c by:
+ *    Vlad Yasevich <vladislav.yasevich@hp.com>
+ *
+ * Any bugs reported given to us we will try to fix... any fixes shared will
+ * be incorporated into the next SCTP release.
+ */
+
+#include <linux/types.h>
+#include <net/sctp/sctp.h>
+#include <linux/crc32c.h>
+
+static inline __u32 sctp_start_cksum(__u8 *buffer, __u16 length)
+{
+	__u32 crc = ~(__u32) 0;
+	__u8  zero[sizeof(__u32)] = {0};
+
+	/* Optimize this routine to be SCTP specific, knowing how
+	 * to skip the checksum field of the SCTP header.
+	 */
+
+	/* Calculate CRC up to the checksum. */
+	crc = crc32c(crc, buffer, sizeof(struct sctphdr) - sizeof(__u32));
+
+	/* Skip checksum field of the header. */
+	crc = crc32c(crc, zero, sizeof(__u32));
+
+	/* Calculate the rest of the CRC. */
+	crc = crc32c(crc, &buffer[sizeof(struct sctphdr)],
+			    length - sizeof(struct sctphdr));
+	return crc;
+}
+
+static inline __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
+{
+	return crc32c(crc32, buffer, length);
+}
+
+static inline __u32 sctp_end_cksum(__u32 crc32)
+{
+	return ntohl(~crc32);
+}