in4_cksum.c revision 1.7
1 /* $NetBSD: in4_cksum.c,v 1.7 2001/11/13 00:32:36 lukem 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/cdefs.h> 68 __KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.7 2001/11/13 00:32:36 lukem Exp $"); 69 70 #include <sys/param.h> 71 #include <sys/mbuf.h> 72 #include <sys/systm.h> 73 #include <sys/socket.h> 74 #include <net/route.h> 75 #include <netinet/in.h> 76 #include <netinet/in_systm.h> 77 #include <netinet/ip.h> 78 #include <netinet/ip_var.h> 79 80 /* 81 * Checksum routine for Internet Protocol family headers (Portable Version). 82 * This is only for IPv4 pseudo header checksum. 83 * No need to clear non-pseudo-header fields in IPv4 header. 84 * len is for actual payload size, and does not include IPv4 header and 85 * skipped header chain (off + len should be equal to the whole packet). 86 * 87 * This routine is very heavily used in the network 88 * code and should be modified for each CPU to be as fast as possible. 89 */ 90 91 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 92 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 93 94 int 95 in4_cksum(m, nxt, off, len) 96 struct mbuf *m; 97 u_int8_t nxt; 98 int off, len; 99 { 100 u_int16_t *w; 101 int sum = 0; 102 int mlen = 0; 103 int byte_swapped = 0; 104 struct ipovly ipov; 105 106 union { 107 u_int8_t c[2]; 108 u_int16_t s; 109 } s_util; 110 union { 111 u_int16_t s[2]; 112 u_int32_t l; 113 } l_util; 114 115 if (nxt != 0) { 116 /* pseudo header */ 117 if (off < sizeof(struct ipovly)) 118 panic("in4_cksum: offset too short"); 119 if (m->m_len < sizeof(struct ip)) 120 panic("in4_cksum: bad mbuf chain"); 121 bzero(&ipov, sizeof(ipov)); 122 ipov.ih_len = htons(len); 123 ipov.ih_pr = nxt; 124 ipov.ih_src = mtod(m, struct ip *)->ip_src; 125 ipov.ih_dst = mtod(m, struct ip *)->ip_dst; 126 w = (u_int16_t *)&ipov; 127 /* assumes sizeof(ipov) == 20 */ 128 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; 129 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; 130 } 131 132 /* skip unnecessary part */ 133 while (m && off > 0) { 134 if (m->m_len > off) 135 break; 136 off -= m->m_len; 137 m = m->m_next; 138 } 139 140 for (;m && len; m = m->m_next) { 141 if (m->m_len == 0) 142 continue; 143 w = (u_int16_t *)(mtod(m, caddr_t) + off); 144 if (mlen == -1) { 145 /* 146 * The first byte of this mbuf is the continuation 147 * of a word spanning between this mbuf and the 148 * last mbuf. 149 * 150 * s_util.c[0] is already saved when scanning previous 151 * mbuf. 152 */ 153 s_util.c[1] = *(u_int8_t *)w; 154 sum += s_util.s; 155 w = (u_int16_t *)((u_int8_t *)w + 1); 156 mlen = m->m_len - off - 1; 157 len--; 158 } else 159 mlen = m->m_len - off; 160 off = 0; 161 if (len < mlen) 162 mlen = len; 163 len -= mlen; 164 /* 165 * Force to even boundary. 166 */ 167 if ((1 & (long) w) && (mlen > 0)) { 168 REDUCE; 169 sum <<= 8; 170 s_util.c[0] = *(u_int8_t *)w; 171 w = (u_int16_t *)((int8_t *)w + 1); 172 mlen--; 173 byte_swapped = 1; 174 } 175 /* 176 * Unroll the loop to make overhead from 177 * branches &c small. 178 */ 179 while ((mlen -= 32) >= 0) { 180 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 181 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 182 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 183 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 184 w += 16; 185 } 186 mlen += 32; 187 while ((mlen -= 8) >= 0) { 188 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 189 w += 4; 190 } 191 mlen += 8; 192 if (mlen == 0 && byte_swapped == 0) 193 continue; 194 REDUCE; 195 while ((mlen -= 2) >= 0) { 196 sum += *w++; 197 } 198 if (byte_swapped) { 199 REDUCE; 200 sum <<= 8; 201 byte_swapped = 0; 202 if (mlen == -1) { 203 s_util.c[1] = *(u_int8_t *)w; 204 sum += s_util.s; 205 mlen = 0; 206 } else 207 mlen = -1; 208 } else if (mlen == -1) 209 s_util.c[0] = *(u_int8_t *)w; 210 } 211 if (len) 212 printf("cksum4: out of data\n"); 213 if (mlen == -1) { 214 /* The last mbuf has odd # of bytes. Follow the 215 standard (the odd byte may be shifted left by 8 bits 216 or not as determined by endian-ness of the machine) */ 217 s_util.c[1] = 0; 218 sum += s_util.s; 219 } 220 REDUCE; 221 return (~sum & 0xffff); 222 } 223
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