get.c revision 1.7 
1/*	$OpenBSD: get.c,v 1.7 2006/04/17 13:17:07 maja Exp $ */
2
3/*
4 * Copyright (c) 1993-2006 Mats O Jansson.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#ifndef lint
28static const char rcsid[] =
29    "$OpenBSD: get.c,v 1.7 2006/04/17 13:17:07 maja Exp $";
30#endif
31
32#include <sys/types.h>
33#include "common/mopdef.h"
34
35u_char
36mopGetChar(u_char *pkt, int *idx)
37{
38	u_char ret;
39
40	ret = pkt[*idx];
41	*idx = *idx + 1;
42	return (ret);
43}
44
45u_short
46mopGetShort(u_char *pkt, int *idx)
47{
48	u_short ret;
49
50	ret = pkt[*idx] + pkt[*idx+1]*256;
51	*idx = *idx + 2;
52	return (ret);
53}
54
55u_short
56mopGetNShort(u_char *pkt, int *idx)
57{
58	u_short ret;
59
60	ret = pkt[*idx]*256 + pkt[*idx+1];
61	*idx = *idx + 2;
62	return (ret);
63}
64
65u_long
66mopGetLong(u_char *pkt, int *idx)
67{
68	u_long ret;
69
70	ret = pkt[*idx] + pkt[*idx+1]*0x100 + pkt[*idx+2]*0x10000 +
71	    pkt[*idx+3]*0x1000000;
72	*idx = *idx + 4;
73	return (ret);
74}
75
76void
77mopGetMulti(u_char *pkt, int *idx, u_char *dest, int size)
78{
79	int i;
80
81	for (i = 0; i < size; i++)
82		dest[i] = pkt[*idx+i];
83	*idx = *idx + size;
84}
85
86int
87mopGetTrans(u_char *pkt, int trans)
88{
89	u_short	ptype;
90
91	if (trans == 0) {
92		ptype = pkt[12]*256 + pkt[13];
93		if (ptype < 1600)
94			trans = TRANS_8023;
95		else
96			trans = TRANS_ETHER;
97	}
98	return (trans);
99}
100
101void
102mopGetHeader(u_char *pkt, int *idx, u_char **dst, u_char **src,
103    u_short *proto, int *len, int trans)
104{
105	*dst = pkt;
106	*src = pkt + 6;
107	*idx = *idx + 12;
108
109	switch (trans) {
110	case TRANS_ETHER:
111		*proto = mopGetNShort(pkt, idx);
112		*len   = (int)mopGetShort(pkt, idx);
113		break;
114	case TRANS_8023:
115		*len   = (int)mopGetNShort(pkt, idx);
116		*idx   = *idx + 6;
117		*proto = mopGetNShort(pkt, idx);
118		break;
119	}
120}
121
122u_short
123mopGetLength(u_char *pkt, int trans)
124{
125	switch (trans) {
126	case TRANS_ETHER:
127		return (pkt[14] + pkt[15]*256);
128	case TRANS_8023:
129		return (pkt[12]*256 + pkt[13]);
130	}
131	return (0);
132}
133