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1.1 root 1: /*
2: * Copyright (c) 1988, 1992, 1993
3: * The Regents of the University of California. 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.
1.1.1.3 root 13: * 3. Neither the name of the University nor the names of its contributors
1.1 root 14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: *
29: * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
30: * in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
31: */
32:
33: #include <slirp.h>
34:
35: /*
36: * Checksum routine for Internet Protocol family headers (Portable Version).
37: *
38: * This routine is very heavily used in the network
39: * code and should be modified for each CPU to be as fast as possible.
1.1.1.2 root 40: *
1.1 root 41: * XXX Since we will never span more than 1 mbuf, we can optimise this
42: */
43:
44: #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
1.1.1.4 ! root 45: #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; \
! 46: (void)ADDCARRY(sum);}
1.1 root 47:
48: int cksum(struct mbuf *m, int len)
49: {
1.1.1.4 ! root 50: register uint16_t *w;
1.1 root 51: register int sum = 0;
52: register int mlen = 0;
53: int byte_swapped = 0;
54:
55: union {
1.1.1.4 ! root 56: uint8_t c[2];
! 57: uint16_t s;
1.1 root 58: } s_util;
59: union {
1.1.1.4 ! root 60: uint16_t s[2];
! 61: uint32_t l;
1.1 root 62: } l_util;
1.1.1.2 root 63:
1.1 root 64: if (m->m_len == 0)
65: goto cont;
1.1.1.4 ! root 66: w = mtod(m, uint16_t *);
1.1.1.2 root 67:
1.1 root 68: mlen = m->m_len;
1.1.1.2 root 69:
1.1 root 70: if (len < mlen)
71: mlen = len;
1.1.1.4 ! root 72: #ifdef DEBUG
1.1 root 73: len -= mlen;
1.1.1.4 ! root 74: #endif
1.1 root 75: /*
76: * Force to even boundary.
77: */
78: if ((1 & (long) w) && (mlen > 0)) {
79: REDUCE;
80: sum <<= 8;
1.1.1.4 ! root 81: s_util.c[0] = *(uint8_t *)w;
! 82: w = (uint16_t *)((int8_t *)w + 1);
1.1 root 83: mlen--;
84: byte_swapped = 1;
85: }
86: /*
87: * Unroll the loop to make overhead from
88: * branches &c small.
89: */
90: while ((mlen -= 32) >= 0) {
91: sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
92: sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
93: sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
94: sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
95: w += 16;
96: }
97: mlen += 32;
98: while ((mlen -= 8) >= 0) {
99: sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
100: w += 4;
101: }
102: mlen += 8;
103: if (mlen == 0 && byte_swapped == 0)
104: goto cont;
105: REDUCE;
106: while ((mlen -= 2) >= 0) {
107: sum += *w++;
108: }
1.1.1.2 root 109:
1.1 root 110: if (byte_swapped) {
111: REDUCE;
112: sum <<= 8;
113: if (mlen == -1) {
1.1.1.4 ! root 114: s_util.c[1] = *(uint8_t *)w;
1.1 root 115: sum += s_util.s;
116: mlen = 0;
117: } else
1.1.1.2 root 118:
1.1 root 119: mlen = -1;
120: } else if (mlen == -1)
1.1.1.4 ! root 121: s_util.c[0] = *(uint8_t *)w;
1.1.1.2 root 122:
1.1 root 123: cont:
124: #ifdef DEBUG
125: if (len) {
126: DEBUG_ERROR((dfd, "cksum: out of data\n"));
127: DEBUG_ERROR((dfd, " len = %d\n", len));
128: }
129: #endif
130: if (mlen == -1) {
131: /* The last mbuf has odd # of bytes. Follow the
132: standard (the odd byte may be shifted left by 8 bits
133: or not as determined by endian-ness of the machine) */
134: s_util.c[1] = 0;
135: sum += s_util.s;
136: }
137: REDUCE;
138: return (~sum & 0xffff);
139: }
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