in4_cksum.c revision 1.6
1 /* $NetBSD: in4_cksum.c,v 1.6 2001/05/19 14:20:40 thorpej Exp $ */ 2 3 /* 4 * Copyright (C) 1999 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * Copyright (c) 1988, 1992, 1993 34 * The Regents of the University of California. All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions 38 * are met: 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 3. All advertising materials mentioning features or use of this software 45 * must display the following acknowledgement: 46 * This product includes software developed by the University of 47 * California, Berkeley and its contributors. 48 * 4. Neither the name of the University nor the names of its contributors 49 * may be used to endorse or promote products derived from this software 50 * without specific prior written permission. 51 * 52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 62 * SUCH DAMAGE. 63 * 64 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 65 */ 66 67 #include <sys/param.h> 68 #include <sys/mbuf.h> 69 #include <sys/systm.h> 70 #include <sys/socket.h> 71 #include <net/route.h> 72 #include <netinet/in.h> 73 #include <netinet/in_systm.h> 74 #include <netinet/ip.h> 75 #include <netinet/ip_var.h> 76 77 /* 78 * Checksum routine for Internet Protocol family headers (Portable Version). 79 * This is only for IPv4 pseudo header checksum. 80 * No need to clear non-pseudo-header fields in IPv4 header. 81 * len is for actual payload size, and does not include IPv4 header and 82 * skipped header chain (off + len should be equal to the whole packet). 83 * 84 * This routine is very heavily used in the network 85 * code and should be modified for each CPU to be as fast as possible. 86 */ 87 88 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 89 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 90 91 int 92 in4_cksum(m, nxt, off, len) 93 struct mbuf *m; 94 u_int8_t nxt; 95 int off, len; 96 { 97 u_int16_t *w; 98 int sum = 0; 99 int mlen = 0; 100 int byte_swapped = 0; 101 struct ipovly ipov; 102 103 union { 104 u_int8_t c[2]; 105 u_int16_t s; 106 } s_util; 107 union { 108 u_int16_t s[2]; 109 u_int32_t l; 110 } l_util; 111 112 if (nxt != 0) { 113 /* pseudo header */ 114 if (off < sizeof(struct ipovly)) 115 panic("in4_cksum: offset too short"); 116 if (m->m_len < sizeof(struct ip)) 117 panic("in4_cksum: bad mbuf chain"); 118 bzero(&ipov, sizeof(ipov)); 119 ipov.ih_len = htons(len); 120 ipov.ih_pr = nxt; 121 ipov.ih_src = mtod(m, struct ip *)->ip_src; 122 ipov.ih_dst = mtod(m, struct ip *)->ip_dst; 123 w = (u_int16_t *)&ipov; 124 /* assumes sizeof(ipov) == 20 */ 125 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; 126 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; 127 } 128 129 /* skip unnecessary part */ 130 while (m && off > 0) { 131 if (m->m_len > off) 132 break; 133 off -= m->m_len; 134 m = m->m_next; 135 } 136 137 for (;m && len; m = m->m_next) { 138 if (m->m_len == 0) 139 continue; 140 w = (u_int16_t *)(mtod(m, caddr_t) + off); 141 if (mlen == -1) { 142 /* 143 * The first byte of this mbuf is the continuation 144 * of a word spanning between this mbuf and the 145 * last mbuf. 146 * 147 * s_util.c[0] is already saved when scanning previous 148 * mbuf. 149 */ 150 s_util.c[1] = *(u_int8_t *)w; 151 sum += s_util.s; 152 w = (u_int16_t *)((u_int8_t *)w + 1); 153 mlen = m->m_len - off - 1; 154 len--; 155 } else 156 mlen = m->m_len - off; 157 off = 0; 158 if (len < mlen) 159 mlen = len; 160 len -= mlen; 161 /* 162 * Force to even boundary. 163 */ 164 if ((1 & (long) w) && (mlen > 0)) { 165 REDUCE; 166 sum <<= 8; 167 s_util.c[0] = *(u_int8_t *)w; 168 w = (u_int16_t *)((int8_t *)w + 1); 169 mlen--; 170 byte_swapped = 1; 171 } 172 /* 173 * Unroll the loop to make overhead from 174 * branches &c small. 175 */ 176 while ((mlen -= 32) >= 0) { 177 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 178 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 179 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 180 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 181 w += 16; 182 } 183 mlen += 32; 184 while ((mlen -= 8) >= 0) { 185 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 186 w += 4; 187 } 188 mlen += 8; 189 if (mlen == 0 && byte_swapped == 0) 190 continue; 191 REDUCE; 192 while ((mlen -= 2) >= 0) { 193 sum += *w++; 194 } 195 if (byte_swapped) { 196 REDUCE; 197 sum <<= 8; 198 byte_swapped = 0; 199 if (mlen == -1) { 200 s_util.c[1] = *(u_int8_t *)w; 201 sum += s_util.s; 202 mlen = 0; 203 } else 204 mlen = -1; 205 } else if (mlen == -1) 206 s_util.c[0] = *(u_int8_t *)w; 207 } 208 if (len) 209 printf("cksum4: out of data\n"); 210 if (mlen == -1) { 211 /* The last mbuf has odd # of bytes. Follow the 212 standard (the odd byte may be shifted left by 8 bits 213 or not as determined by endian-ness of the machine) */ 214 s_util.c[1] = 0; 215 sum += s_util.s; 216 } 217 REDUCE; 218 return (~sum & 0xffff); 219 } 220
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