1139823Simp/*- 21541Srgrimes * Copyright (c) 1988, 1992, 1993 31541Srgrimes * The Regents of the University of California. All rights reserved. 41541Srgrimes * 51541Srgrimes * Redistribution and use in source and binary forms, with or without 61541Srgrimes * modification, are permitted provided that the following conditions 71541Srgrimes * are met: 81541Srgrimes * 1. Redistributions of source code must retain the above copyright 91541Srgrimes * notice, this list of conditions and the following disclaimer. 101541Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111541Srgrimes * notice, this list of conditions and the following disclaimer in the 121541Srgrimes * documentation and/or other materials provided with the distribution. 131541Srgrimes * 4. Neither the name of the University nor the names of its contributors 141541Srgrimes * may be used to endorse or promote products derived from this software 151541Srgrimes * without specific prior written permission. 161541Srgrimes * 171541Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 181541Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 191541Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 201541Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 211541Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 221541Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 231541Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 241541Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 251541Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 261541Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 271541Srgrimes * SUCH DAMAGE. 281541Srgrimes * 291541Srgrimes * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 301541Srgrimes */ 311541Srgrimes 32172467Ssilby#include <sys/cdefs.h> 33172467Ssilby__FBSDID("$FreeBSD$"); 34172467Ssilby 351541Srgrimes#include <sys/param.h> 361541Srgrimes#include <sys/mbuf.h> 371541Srgrimes 381541Srgrimes/* 391541Srgrimes * Checksum routine for Internet Protocol family headers (Portable Version). 401541Srgrimes * 411541Srgrimes * This routine is very heavily used in the network 421541Srgrimes * code and should be modified for each CPU to be as fast as possible. 431541Srgrimes */ 441541Srgrimes 451541Srgrimes#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 461541Srgrimes#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 471541Srgrimes 481541Srgrimesint 49169454Srwatsonin_cksum(struct mbuf *m, int len) 501541Srgrimes{ 511541Srgrimes register u_short *w; 521541Srgrimes register int sum = 0; 531541Srgrimes register int mlen = 0; 541541Srgrimes int byte_swapped = 0; 551541Srgrimes 561541Srgrimes union { 571541Srgrimes char c[2]; 581541Srgrimes u_short s; 591541Srgrimes } s_util; 601541Srgrimes union { 611541Srgrimes u_short s[2]; 621541Srgrimes long l; 631541Srgrimes } l_util; 641541Srgrimes 651541Srgrimes for (;m && len; m = m->m_next) { 661541Srgrimes if (m->m_len == 0) 671541Srgrimes continue; 681541Srgrimes w = mtod(m, u_short *); 691541Srgrimes if (mlen == -1) { 701541Srgrimes /* 711541Srgrimes * The first byte of this mbuf is the continuation 721541Srgrimes * of a word spanning between this mbuf and the 731541Srgrimes * last mbuf. 741541Srgrimes * 758876Srgrimes * s_util.c[0] is already saved when scanning previous 761541Srgrimes * mbuf. 771541Srgrimes */ 781541Srgrimes s_util.c[1] = *(char *)w; 791541Srgrimes sum += s_util.s; 801541Srgrimes w = (u_short *)((char *)w + 1); 811541Srgrimes mlen = m->m_len - 1; 821541Srgrimes len--; 831541Srgrimes } else 841541Srgrimes mlen = m->m_len; 851541Srgrimes if (len < mlen) 861541Srgrimes mlen = len; 871541Srgrimes len -= mlen; 881541Srgrimes /* 891541Srgrimes * Force to even boundary. 901541Srgrimes */ 91238941Sluigi if ((1 & (uintptr_t) w) && (mlen > 0)) { 921541Srgrimes REDUCE; 931541Srgrimes sum <<= 8; 941541Srgrimes s_util.c[0] = *(u_char *)w; 951541Srgrimes w = (u_short *)((char *)w + 1); 961541Srgrimes mlen--; 971541Srgrimes byte_swapped = 1; 981541Srgrimes } 991541Srgrimes /* 1001541Srgrimes * Unroll the loop to make overhead from 1011541Srgrimes * branches &c small. 1021541Srgrimes */ 1031541Srgrimes while ((mlen -= 32) >= 0) { 1041541Srgrimes sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 1051541Srgrimes sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 1061541Srgrimes sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 1071541Srgrimes sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 1081541Srgrimes w += 16; 1091541Srgrimes } 1101541Srgrimes mlen += 32; 1111541Srgrimes while ((mlen -= 8) >= 0) { 1121541Srgrimes sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 1131541Srgrimes w += 4; 1141541Srgrimes } 1151541Srgrimes mlen += 8; 1161541Srgrimes if (mlen == 0 && byte_swapped == 0) 1171541Srgrimes continue; 1181541Srgrimes REDUCE; 1191541Srgrimes while ((mlen -= 2) >= 0) { 1201541Srgrimes sum += *w++; 1211541Srgrimes } 1221541Srgrimes if (byte_swapped) { 1231541Srgrimes REDUCE; 1241541Srgrimes sum <<= 8; 1251541Srgrimes byte_swapped = 0; 1261541Srgrimes if (mlen == -1) { 1271541Srgrimes s_util.c[1] = *(char *)w; 1281541Srgrimes sum += s_util.s; 1291541Srgrimes mlen = 0; 1301541Srgrimes } else 1311541Srgrimes mlen = -1; 1321541Srgrimes } else if (mlen == -1) 1331541Srgrimes s_util.c[0] = *(char *)w; 1341541Srgrimes } 1351541Srgrimes if (len) 1361541Srgrimes printf("cksum: out of data\n"); 1371541Srgrimes if (mlen == -1) { 1381541Srgrimes /* The last mbuf has odd # of bytes. Follow the 1391541Srgrimes standard (the odd byte may be shifted left by 8 bits 1401541Srgrimes or not as determined by endian-ness of the machine) */ 1411541Srgrimes s_util.c[1] = 0; 1421541Srgrimes sum += s_util.s; 1431541Srgrimes } 1441541Srgrimes REDUCE; 1451541Srgrimes return (~sum & 0xffff); 1461541Srgrimes} 147