| 1 | /* |
| 2 | * Copyright (c) 1988 Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * 3. All advertising materials mentioning features or use of this software |
| 14 | * must display the following acknowledgement: |
| 15 | * This product includes software developed by the University of |
| 16 | * California, Berkeley and its contributors. |
| 17 | * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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 | * @(#)in_cksum.c 7.3 (Berkeley) 6/28/90 |
| 34 | */ |
| 35 | |
| 36 | #include "../h/types.h" |
| 37 | #include "../h/mbuf.h" |
| 38 | |
| 39 | /* |
| 40 | * Checksum routine for Internet Protocol family headers (Portable Version). |
| 41 | * |
| 42 | * This routine is very heavily used in the network |
| 43 | * code and should be modified for each CPU to be as fast as possible. |
| 44 | */ |
| 45 | |
| 46 | #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) |
| 47 | #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} |
| 48 | |
| 49 | in_cksum_c(m, len) |
| 50 | register struct mbuf *m; |
| 51 | register int len; |
| 52 | { |
| 53 | register u_short *w; |
| 54 | register int sum = 0; |
| 55 | register int mlen = 0; |
| 56 | int byte_swapped = 0; |
| 57 | |
| 58 | union { |
| 59 | char c[2]; |
| 60 | u_short s; |
| 61 | } s_util; |
| 62 | union { |
| 63 | u_short s[2]; |
| 64 | long l; |
| 65 | } l_util; |
| 66 | |
| 67 | for (;m && len; m = m->m_next) { |
| 68 | if (m->m_len == 0) |
| 69 | continue; |
| 70 | w = mtod(m, u_short *); |
| 71 | if (mlen == -1) { |
| 72 | /* |
| 73 | * The first byte of this mbuf is the continuation |
| 74 | * of a word spanning between this mbuf and the |
| 75 | * last mbuf. |
| 76 | * |
| 77 | * s_util.c[0] is already saved when scanning previous |
| 78 | * mbuf. |
| 79 | */ |
| 80 | s_util.c[1] = *(char *)w; |
| 81 | sum += s_util.s; |
| 82 | w = (u_short *)((char *)w + 1); |
| 83 | mlen = m->m_len - 1; |
| 84 | len--; |
| 85 | } else |
| 86 | mlen = m->m_len; |
| 87 | if (len < mlen) |
| 88 | mlen = len; |
| 89 | len -= mlen; |
| 90 | /* |
| 91 | * Force to even boundary. |
| 92 | */ |
| 93 | if ((1 & (int) w) && (mlen > 0)) { |
| 94 | REDUCE; |
| 95 | sum <<= 8; |
| 96 | s_util.c[0] = *(u_char *)w; |
| 97 | w = (u_short *)((char *)w + 1); |
| 98 | mlen--; |
| 99 | byte_swapped = 1; |
| 100 | } |
| 101 | /* |
| 102 | * Unroll the loop to make overhead from |
| 103 | * branches &c small. |
| 104 | */ |
| 105 | while ((mlen -= 32) >= 0) { |
| 106 | sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; |
| 107 | sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; |
| 108 | sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; |
| 109 | sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; |
| 110 | w += 16; |
| 111 | } |
| 112 | mlen += 32; |
| 113 | while ((mlen -= 8) >= 0) { |
| 114 | sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; |
| 115 | w += 4; |
| 116 | } |
| 117 | mlen += 8; |
| 118 | if (mlen == 0 && byte_swapped == 0) |
| 119 | continue; |
| 120 | REDUCE; |
| 121 | while ((mlen -= 2) >= 0) { |
| 122 | sum += *w++; |
| 123 | } |
| 124 | if (byte_swapped) { |
| 125 | REDUCE; |
| 126 | sum <<= 8; |
| 127 | byte_swapped = 0; |
| 128 | if (mlen == -1) { |
| 129 | s_util.c[1] = *(char *)w; |
| 130 | sum += s_util.s; |
| 131 | mlen = 0; |
| 132 | } else |
| 133 | mlen = -1; |
| 134 | } else if (mlen == -1) |
| 135 | s_util.c[0] = *(char *)w; |
| 136 | } |
| 137 | if (len) |
| 138 | printf("cksum: out of data\n"); |
| 139 | if (mlen == -1) { |
| 140 | /* The last mbuf has odd # of bytes. Follow the |
| 141 | standard (the odd byte may be shifted left by 8 bits |
| 142 | or not as determined by endian-ness of the machine) */ |
| 143 | s_util.c[1] = 0; |
| 144 | sum += s_util.s; |
| 145 | } |
| 146 | REDUCE; |
| 147 | return (~sum & 0xffff); |
| 148 | } |