[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>

[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>
Vlad Yasevich · David S. Miller
1 parent 1bf40954cf
Showing 7 changed files with 82 additions and 230 deletions Side-by-side Diff
include/net/sctp/checksum.h
include/net/sctp/sctp.h
net/sctp/Kconfig
net/sctp/Makefile
net/sctp/crc32c.c
net/sctp/input.c
net/sctp/output.c
+/* 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);
+}
@@ -150,13 +150,6 @@
 int sctp_primitive_ASCONF(struct sctp_association *, void *arg);
  
 /*
- * sctp/crc32c.c
- */
-__u32 sctp_start_cksum(__u8 *ptr, __u16 count);
-__u32 sctp_update_cksum(__u8 *ptr, __u16 count, __u32 cksum);
-__u32 sctp_end_cksum(__u32 cksum);
-
-/*
  * sctp/input.c
  */
 int sctp_rcv(struct sk_buff *skb);
@@ -10,6 +10,7 @@
 	select CRYPTO_HMAC
 	select CRYPTO_SHA1
 	select CRYPTO_MD5 if SCTP_HMAC_MD5
+	select LIBCRC32C
 	---help---
 	  Stream Control Transmission Protocol
  
@@ -9,7 +9,7 @@
 	  transport.o chunk.o sm_make_chunk.o ulpevent.o \
 	  inqueue.o outqueue.o ulpqueue.o command.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
-	  output.o input.o debug.o ssnmap.o proc.o crc32c.o \
+	  output.o input.o debug.o ssnmap.o proc.o \
 	  auth.o
  
 sctp-$(CONFIG_SCTP_DBG_OBJCNT) += objcnt.o
-/* 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>
- *
- * Any bugs reported given to us we will try to fix... any fixes shared will
- * be incorporated into the next SCTP release.
- */
-
-/* The following code has been taken directly from
- * draft-ietf-tsvwg-sctpcsum-03.txt
- *
- * The code has now been modified specifically for SCTP knowledge.
- */
-
-#include <linux/types.h>
-#include <net/sctp/sctp.h>
-
-#define CRC32C_POLY 0x1EDC6F41
-#define CRC32C(c,d) (c=(c>>8)^crc_c[(c^(d))&0xFF])
-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
-/* Copyright 2001, D. Otis.  Use this program, code or tables    */
-/* extracted from it, as desired without restriction.            */
-/*                                                               */
-/* 32 Bit Reflected CRC table generation for SCTP.               */
-/* To accommodate serial byte data being shifted out least       */
-/* significant bit first, the table's 32 bit words are reflected */
-/* which flips both byte and bit MS and LS positions.  The CRC   */
-/* is calculated MS bits first from the perspective of the serial*/
-/* stream.  The x^32 term is implied and the x^0 term may also   */
-/* be shown as +1.  The polynomial code used is 0x1EDC6F41.      */
-/* Castagnoli93                                                  */
-/* x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+  */
-/* x^11+x^10+x^9+x^8+x^6+x^0                                     */
-/* Guy Castagnoli Stefan Braeuer and Martin Herrman              */
-/* "Optimization of Cyclic Redundancy-Check Codes                */
-/* with 24 and 32 Parity Bits",                                  */
-/* IEEE Transactions on Communications, Vol.41, No.6, June 1993  */
-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
-static const __u32 crc_c[256] = {
-	0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4,
-	0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
-	0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B,
-	0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
-	0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B,
-	0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
-	0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54,
-	0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
-	0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A,
-	0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
-	0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5,
-	0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
-	0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45,
-	0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
-	0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
-	0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
-	0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48,
-	0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
-	0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687,
-	0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
-	0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927,
-	0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
-	0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8,
-	0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
-	0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
-	0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
-	0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859,
-	0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
-	0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9,
-	0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
-	0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36,
-	0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
-	0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C,
-	0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
-	0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
-	0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
-	0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3,
-	0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
-	0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C,
-	0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
-	0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652,
-	0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
-	0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D,
-	0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
-	0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
-	0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
-	0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2,
-	0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
-	0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530,
-	0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
-	0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF,
-	0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
-	0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F,
-	0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
-	0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
-	0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
-	0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE,
-	0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
-	0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321,
-	0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
-	0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81,
-	0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
-	0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E,
-	0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351,
-};
-
-__u32 sctp_start_cksum(__u8 *buffer, __u16 length)
-{
-	__u32 crc32 = ~(__u32) 0;
-	__u32 i;
-
-	/* Optimize this routine to be SCTP specific, knowing how
-	 * to skip the checksum field of the SCTP header.
-	 */
-
-	/* Calculate CRC up to the checksum. */
-	for (i = 0; i < (sizeof(struct sctphdr) - sizeof(__u32)); i++)
-		CRC32C(crc32, buffer[i]);
-
-	/* Skip checksum field of the header. */
-	for (i = 0; i < sizeof(__u32); i++)
-		CRC32C(crc32, 0);
-
-	/* Calculate the rest of the CRC. */
-	for (i = sizeof(struct sctphdr); i < length ; i++)
-		CRC32C(crc32, buffer[i]);
-
-	return crc32;
-}
-
-__u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
-{
-	__u32 i;
-
-	for (i = 0; i < length ; i++)
-		CRC32C(crc32, buffer[i]);
-
-	return crc32;
-}
-
-#if 0
-__u32 sctp_update_copy_cksum(__u8 *to, __u8 *from, __u16 length, __u32 crc32)
-{
-	__u32 i;
-	__u32 *_to = (__u32 *)to;
-	__u32 *_from = (__u32 *)from;
-
-	for (i = 0; i < (length/4); i++) {
-		_to[i] = _from[i];
-		CRC32C(crc32, from[i*4]);
-		CRC32C(crc32, from[i*4+1]);
-		CRC32C(crc32, from[i*4+2]);
-		CRC32C(crc32, from[i*4+3]);
-	}
-
-	return crc32;
-}
-#endif  /*  0  */
-
-__u32 sctp_end_cksum(__u32 crc32)
-{
-	__u32 result;
-	__u8 byte0, byte1, byte2, byte3;
-
-	result = ~crc32;
-
-	/*  result  now holds the negated polynomial remainder;
-	 *  since the table and algorithm is "reflected" [williams95].
-	 *  That is,  result has the same value as if we mapped the message
-	 *  to a polyomial, computed the host-bit-order polynomial
-	 *  remainder, performed final negation, then did an end-for-end
-	 *  bit-reversal.
-	 *  Note that a 32-bit bit-reversal is identical to four inplace
-	 *  8-bit reversals followed by an end-for-end byteswap.
-	 *  In other words, the bytes of each bit are in the right order,
-	 *  but the bytes have been byteswapped.  So we now do an explicit
-	 *  byteswap.  On a little-endian machine, this byteswap and
-	 *  the final ntohl cancel out and could be elided.
-	 */
-	byte0 = result & 0xff;
-	byte1 = (result>>8) & 0xff;
-	byte2 = (result>>16) & 0xff;
-	byte3 = (result>>24) & 0xff;
-
-	crc32 = ((byte0 << 24) |
-		 (byte1 << 16) |
-		 (byte2 << 8)  |
-		 byte3);
-	return crc32;
-}
@@ -60,6 +60,7 @@
 #include <net/xfrm.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
+#include <net/sctp/checksum.h>
  
 /* Forward declarations for internal helpers. */
 static int sctp_rcv_ootb(struct sk_buff *);
@@ -60,6 +60,7 @@
  
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
+#include <net/sctp/checksum.h>
  
 /* Forward declarations for private helpers. */
 static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet,
	1	+/* SCTP kernel reference Implementation
	2	+ * Copyright (c) 1999-2001 Motorola, Inc.
	3	+ * Copyright (c) 2001-2003 International Business Machines, Corp.
	4	+ *
	5	+ * This file is part of the SCTP kernel reference Implementation
	6	+ *
	7	+ * SCTP Checksum functions
	8	+ *
	9	+ * The SCTP reference implementation is free software;
	10	+ * you can redistribute it and/or modify it under the terms of
	11	+ * the GNU General Public License as published by
	12	+ * the Free Software Foundation; either version 2, or (at your option)
	13	+ * any later version.
	14	+ *
	15	+ * The SCTP reference implementation is distributed in the hope that it
	16	+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied
	17	+ * ************************
	18	+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
	19	+ * See the GNU General Public License for more details.
	20	+ *
	21	+ * You should have received a copy of the GNU General Public License
	22	+ * along with GNU CC; see the file COPYING. If not, write to
	23	+ * the Free Software Foundation, 59 Temple Place - Suite 330,
	24	+ * Boston, MA 02111-1307, USA.
	25	+ *
	26	+ * Please send any bug reports or fixes you make to the
	27	+ * email address(es):
	28	+ * lksctp developers <lksctp-developers@lists.sourceforge.net>
	29	+ *
	30	+ * Or submit a bug report through the following website:
	31	+ * http://www.sf.net/projects/lksctp
	32	+ *
	33	+ * Written or modified by:
	34	+ * Dinakaran Joseph
	35	+ * Jon Grimm <jgrimm@us.ibm.com>
	36	+ * Sridhar Samudrala <sri@us.ibm.com>
	37	+ *
	38	+ * Rewritten to use libcrc32c by:
	39	+ * Vlad Yasevich <vladislav.yasevich@hp.com>
	40	+ *
	41	+ * Any bugs reported given to us we will try to fix... any fixes shared will
	42	+ * be incorporated into the next SCTP release.
	43	+ */
	44	+
	45	+#include <linux/types.h>
	46	+#include <net/sctp/sctp.h>
	47	+#include <linux/crc32c.h>
	48	+
	49	+static inline __u32 sctp_start_cksum(__u8 *buffer, __u16 length)
	50	+{
	51	+ __u32 crc = ~(__u32) 0;
	52	+ __u8 zero[sizeof(__u32)] = {0};
	53	+
	54	+ /* Optimize this routine to be SCTP specific, knowing how
	55	+ * to skip the checksum field of the SCTP header.
	56	+ */
	57	+
	58	+ /* Calculate CRC up to the checksum. */
	59	+ crc = crc32c(crc, buffer, sizeof(struct sctphdr) - sizeof(__u32));
	60	+
	61	+ /* Skip checksum field of the header. */
	62	+ crc = crc32c(crc, zero, sizeof(__u32));
	63	+
	64	+ /* Calculate the rest of the CRC. */
	65	+ crc = crc32c(crc, &buffer[sizeof(struct sctphdr)],
	66	+ length - sizeof(struct sctphdr));
	67	+ return crc;
	68	+}
	69	+
	70	+static inline __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
	71	+{
	72	+ return crc32c(crc32, buffer, length);
	73	+}
	74	+
	75	+static inline __u32 sctp_end_cksum(__u32 crc32)
	76	+{
	77	+ return ntohl(~crc32);
	78	+}
...	...	@@ -150,13 +150,6 @@
150	150	int sctp_primitive_ASCONF(struct sctp_association , void arg);
151	151
152	152	/*
153		- * sctp/crc32c.c
154		- */
155		-__u32 sctp_start_cksum(__u8 *ptr, __u16 count);
156		-__u32 sctp_update_cksum(__u8 *ptr, __u16 count, __u32 cksum);
157		-__u32 sctp_end_cksum(__u32 cksum);
158		-
159		-/*
160	153	* sctp/input.c
161	154	*/
162	155	int sctp_rcv(struct sk_buff *skb);
...	...	@@ -10,6 +10,7 @@
10	10	select CRYPTO_HMAC
11	11	select CRYPTO_SHA1
12	12	select CRYPTO_MD5 if SCTP_HMAC_MD5
	13	+ select LIBCRC32C
13	14	---help---
14	15	Stream Control Transmission Protocol
15	16
...	...	@@ -9,7 +9,7 @@
9	9	transport.o chunk.o sm_make_chunk.o ulpevent.o \
10	10	inqueue.o outqueue.o ulpqueue.o command.o \
11	11	tsnmap.o bind_addr.o socket.o primitive.o \
12		- output.o input.o debug.o ssnmap.o proc.o crc32c.o \
	12	+ output.o input.o debug.o ssnmap.o proc.o \
13	13	auth.o
14	14
15	15	sctp-$(CONFIG_SCTP_DBG_OBJCNT) += objcnt.o
1		-/* SCTP kernel reference Implementation
2		- * Copyright (c) 1999-2001 Motorola, Inc.
3		- * Copyright (c) 2001-2003 International Business Machines, Corp.
4		- *
5		- * This file is part of the SCTP kernel reference Implementation
6		- *
7		- * SCTP Checksum functions
8		- *
9		- * The SCTP reference implementation is free software;
10		- * you can redistribute it and/or modify it under the terms of
11		- * the GNU General Public License as published by
12		- * the Free Software Foundation; either version 2, or (at your option)
13		- * any later version.
14		- *
15		- * The SCTP reference implementation is distributed in the hope that it
16		- * will be useful, but WITHOUT ANY WARRANTY; without even the implied
17		- * ************************
18		- * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
19		- * See the GNU General Public License for more details.
20		- *
21		- * You should have received a copy of the GNU General Public License
22		- * along with GNU CC; see the file COPYING. If not, write to
23		- * the Free Software Foundation, 59 Temple Place - Suite 330,
24		- * Boston, MA 02111-1307, USA.
25		- *
26		- * Please send any bug reports or fixes you make to the
27		- * email address(es):
28		- * lksctp developers <lksctp-developers@lists.sourceforge.net>
29		- *
30		- * Or submit a bug report through the following website:
31		- * http://www.sf.net/projects/lksctp
32		- *
33		- * Written or modified by:
34		- * Dinakaran Joseph
35		- * Jon Grimm <jgrimm@us.ibm.com>
36		- * Sridhar Samudrala <sri@us.ibm.com>
37		- *
38		- * Any bugs reported given to us we will try to fix... any fixes shared will
39		- * be incorporated into the next SCTP release.
40		- */
41		-
42		-/* The following code has been taken directly from
43		- * draft-ietf-tsvwg-sctpcsum-03.txt
44		- *
45		- * The code has now been modified specifically for SCTP knowledge.
46		- */
47		-
48		-#include <linux/types.h>
49		-#include <net/sctp/sctp.h>
50		-
51		-#define CRC32C_POLY 0x1EDC6F41
52		-#define CRC32C(c,d) (c=(c>>8)^crc_c[(c^(d))&0xFF])
53		-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
54		-/* Copyright 2001, D. Otis. Use this program, code or tables */
55		-/* extracted from it, as desired without restriction. */
56		-/* */
57		-/* 32 Bit Reflected CRC table generation for SCTP. */
58		-/* To accommodate serial byte data being shifted out least */
59		-/* significant bit first, the table's 32 bit words are reflected */
60		-/* which flips both byte and bit MS and LS positions. The CRC */
61		-/* is calculated MS bits first from the perspective of the serial*/
62		-/* stream. The x^32 term is implied and the x^0 term may also */
63		-/* be shown as +1. The polynomial code used is 0x1EDC6F41. */
64		-/* Castagnoli93 */
65		-/* x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+ */
66		-/* x^11+x^10+x^9+x^8+x^6+x^0 */
67		-/* Guy Castagnoli Stefan Braeuer and Martin Herrman */
68		-/* "Optimization of Cyclic Redundancy-Check Codes */
69		-/* with 24 and 32 Parity Bits", */
70		-/* IEEE Transactions on Communications, Vol.41, No.6, June 1993 */
71		-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
72		-static const __u32 crc_c[256] = {
73		- 0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4,
74		- 0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
75		- 0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B,
76		- 0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
77		- 0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B,
78		- 0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
79		- 0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54,
80		- 0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
81		- 0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A,
82		- 0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
83		- 0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5,
84		- 0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
85		- 0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45,
86		- 0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
87		- 0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
88		- 0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
89		- 0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48,
90		- 0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
91		- 0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687,
92		- 0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
93		- 0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927,
94		- 0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
95		- 0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8,
96		- 0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
97		- 0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
98		- 0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
99		- 0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859,
100		- 0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
101		- 0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9,
102		- 0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
103		- 0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36,
104		- 0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
105		- 0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C,
106		- 0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
107		- 0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
108		- 0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
109		- 0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3,
110		- 0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
111		- 0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C,
112		- 0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
113		- 0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652,
114		- 0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
115		- 0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D,
116		- 0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
117		- 0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
118		- 0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
119		- 0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2,
120		- 0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
121		- 0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530,
122		- 0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
123		- 0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF,
124		- 0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
125		- 0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F,
126		- 0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
127		- 0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
128		- 0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
129		- 0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE,
130		- 0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
131		- 0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321,
132		- 0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
133		- 0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81,
134		- 0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
135		- 0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E,
136		- 0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351,
137		-};
138		-
139		-__u32 sctp_start_cksum(__u8 *buffer, __u16 length)
140		-{
141		- __u32 crc32 = ~(__u32) 0;
142		- __u32 i;
143		-
144		- /* Optimize this routine to be SCTP specific, knowing how
145		- * to skip the checksum field of the SCTP header.
146		- */
147		-
148		- /* Calculate CRC up to the checksum. */
149		- for (i = 0; i < (sizeof(struct sctphdr) - sizeof(__u32)); i++)
150		- CRC32C(crc32, buffer[i]);
151		-
152		- /* Skip checksum field of the header. */
153		- for (i = 0; i < sizeof(__u32); i++)
154		- CRC32C(crc32, 0);
155		-
156		- /* Calculate the rest of the CRC. */
157		- for (i = sizeof(struct sctphdr); i < length ; i++)
158		- CRC32C(crc32, buffer[i]);
159		-
160		- return crc32;
161		-}
162		-
163		-__u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
164		-{
165		- __u32 i;
166		-
167		- for (i = 0; i < length ; i++)
168		- CRC32C(crc32, buffer[i]);
169		-
170		- return crc32;
171		-}
172		-
173		-#if 0
174		-__u32 sctp_update_copy_cksum(__u8 to, __u8 from, __u16 length, __u32 crc32)
175		-{
176		- __u32 i;
177		- __u32 _to = (__u32 )to;
178		- __u32 _from = (__u32 )from;
179		-
180		- for (i = 0; i < (length/4); i++) {
181		- _to[i] = _from[i];
182		- CRC32C(crc32, from[i*4]);
183		- CRC32C(crc32, from[i*4+1]);
184		- CRC32C(crc32, from[i*4+2]);
185		- CRC32C(crc32, from[i*4+3]);
186		- }
187		-
188		- return crc32;
189		-}
190		-#endif /* 0 */
191		-
192		-__u32 sctp_end_cksum(__u32 crc32)
193		-{
194		- __u32 result;
195		- __u8 byte0, byte1, byte2, byte3;
196		-
197		- result = ~crc32;
198		-
199		- /* result now holds the negated polynomial remainder;
200		- * since the table and algorithm is "reflected" [williams95].
201		- * That is, result has the same value as if we mapped the message
202		- * to a polyomial, computed the host-bit-order polynomial
203		- * remainder, performed final negation, then did an end-for-end
204		- * bit-reversal.
205		- * Note that a 32-bit bit-reversal is identical to four inplace
206		- * 8-bit reversals followed by an end-for-end byteswap.
207		- * In other words, the bytes of each bit are in the right order,
208		- * but the bytes have been byteswapped. So we now do an explicit
209		- * byteswap. On a little-endian machine, this byteswap and
210		- * the final ntohl cancel out and could be elided.
211		- */
212		- byte0 = result & 0xff;
213		- byte1 = (result>>8) & 0xff;
214		- byte2 = (result>>16) & 0xff;
215		- byte3 = (result>>24) & 0xff;
216		-
217		- crc32 = ((byte0 << 24) \|
218		- (byte1 << 16) \|
219		- (byte2 << 8) \|
220		- byte3);
221		- return crc32;
222		-}
...	...	@@ -60,6 +60,7 @@
60	60	#include <net/xfrm.h>
61	61	#include <net/sctp/sctp.h>
62	62	#include <net/sctp/sm.h>
	63	+#include <net/sctp/checksum.h>
63	64
64	65	/* Forward declarations for internal helpers. */
65	66	static int sctp_rcv_ootb(struct sk_buff *);