1 /* $OpenBSD: in4_cksum.c,v 1.4 2001/06/24 23:45:16 angelos Exp $ */ 2 3 /* $NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $ */ 4 5 /* 6 * Copyright (C) 1999 WIDE Project. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the project nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * Copyright (c) 1988, 1992, 1993 36 * The Regents of the University of California. All rights reserved. 37 * 38 * Redistribution and use in source and binary forms, with or without 39 * modification, are permitted provided that the following conditions 40 * are met: 41 * 1. Redistributions of source code must retain the above copyright 42 * notice, this list of conditions and the following disclaimer. 43 * 2. Redistributions in binary form must reproduce the above copyright 44 * notice, this list of conditions and the following disclaimer in the 45 * documentation and/or other materials provided with the distribution. 46 * 3. All advertising materials mentioning features or use of this software 47 * must display the following acknowledgement: 48 * This product includes software developed by the University of 49 * California, Berkeley and its contributors. 50 * 4. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 67 */ 68 69 #include <sys/param.h> 70 #include <sys/mbuf.h> 71 #include <sys/systm.h> 72 #include <sys/socket.h> 73 #include <net/route.h> 74 #include <netinet/in.h> 75 #include <netinet/in_systm.h> 76 #include <netinet/ip.h> 77 #include <netinet/ip_var.h> 78 79 /* 80 * Checksum routine for Internet Protocol family headers (Portable Version). 81 * This is only for IPv4 pseudo header checksum. 82 * No need to clear non-pseudo-header fields in IPv4 header. 83 * len is for actual payload size, and does not include IPv4 header and 84 * skipped header chain (off + len should be equal to the whole packet). 85 * 86 * This routine is very heavily used in the network 87 * code and should be modified for each CPU to be as fast as possible. 88 */ 89 90 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 91 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 92 93 int 94 in4_cksum(m, nxt, off, len) 95 register struct mbuf *m; 96 u_int8_t nxt; 97 register int off, len; 98 { 99 register u_int16_t *w; 100 register int sum = 0; 101 register int mlen = 0; 102 int byte_swapped = 0; 103 struct ipovly ipov; 104 105 union { 106 u_int8_t c[2]; 107 u_int16_t s; 108 } s_util; 109 union { 110 u_int16_t s[2]; 111 u_int32_t l; 112 } l_util; 113 114 if (nxt != 0) { 115 /* pseudo header */ 116 if (off < sizeof(struct ipovly)) 117 panic("in4_cksum: offset too short"); 118 if (m->m_len < sizeof(struct ip)) 119 panic("in4_cksum: bad mbuf chain"); 120 bzero(&ipov, sizeof(ipov)); 121 ipov.ih_len = htons(len); 122 ipov.ih_pr = nxt; 123 ipov.ih_src = mtod(m, struct ip *)->ip_src; 124 ipov.ih_dst = mtod(m, struct ip *)->ip_dst; 125 w = (u_int16_t *)&ipov; 126 /* assumes sizeof(ipov) == 20 */ 127 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; 128 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; 129 } 130 131 /* skip unnecessary part */ 132 while (m && off > 0) { 133 if (m->m_len > off) 134 break; 135 off -= m->m_len; 136 m = m->m_next; 137 } 138 139 for (;m && len; m = m->m_next) { 140 if (m->m_len == 0) 141 continue; 142 w = (u_int16_t *)(mtod(m, caddr_t) + off); 143 if (mlen == -1) { 144 /* 145 * The first byte of this mbuf is the continuation 146 * of a word spanning between this mbuf and the 147 * last mbuf. 148 * 149 * s_util.c[0] is already saved when scanning previous 150 * mbuf. 151 */ 152 s_util.c[1] = *(u_int8_t *)w; 153 sum += s_util.s; 154 w = (u_int16_t *)((u_int8_t *)w + 1); 155 mlen = m->m_len - off - 1; 156 len--; 157 } else 158 mlen = m->m_len - off; 159 off = 0; 160 if (len < mlen) 161 mlen = len; 162 len -= mlen; 163 /* 164 * Force to even boundary. 165 */ 166 if ((1 & (long) w) && (mlen > 0)) { 167 REDUCE; 168 sum <<= 8; 169 s_util.c[0] = *(u_int8_t *)w; 170 w = (u_int16_t *)((int8_t *)w + 1); 171 mlen--; 172 byte_swapped = 1; 173 } 174 /* 175 * Unroll the loop to make overhead from 176 * branches &c small. 177 */ 178 while ((mlen -= 32) >= 0) { 179 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 180 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 181 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 182 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 183 w += 16; 184 } 185 mlen += 32; 186 while ((mlen -= 8) >= 0) { 187 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 188 w += 4; 189 } 190 mlen += 8; 191 if (mlen == 0 && byte_swapped == 0) 192 continue; 193 REDUCE; 194 while ((mlen -= 2) >= 0) { 195 sum += *w++; 196 } 197 if (byte_swapped) { 198 REDUCE; 199 sum <<= 8; 200 byte_swapped = 0; 201 if (mlen == -1) { 202 s_util.c[1] = *(u_int8_t *)w; 203 sum += s_util.s; 204 mlen = 0; 205 } else 206 mlen = -1; 207 } else if (mlen == -1) 208 s_util.c[0] = *(u_int8_t *)w; 209 } 210 if (len) 211 printf("cksum4: out of data\n"); 212 if (mlen == -1) { 213 /* The last mbuf has odd # of bytes. Follow the 214 standard (the odd byte may be shifted left by 8 bits 215 or not as determined by endian-ness of the machine) */ 216 s_util.c[1] = 0; 217 sum += s_util.s; 218 } 219 REDUCE; 220 return (~sum & 0xffff); 221 } 222