1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/* packet-ieee8023.c
* Routine for dissecting 802.3 (as opposed to D/I/X Ethernet) packets.
*
* $Id: packet-ieee8023.c,v 1.7 2004/02/20 10:21:46 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <glib.h>
#include <epan/packet.h>
#include "packet-ieee8023.h"
#include "packet-eth.h"
static dissector_handle_t ipx_handle;
static dissector_handle_t llc_handle;
void
dissect_802_3(int length, gboolean is_802_2, tvbuff_t *tvb,
int offset_after_length, packet_info *pinfo, proto_tree *tree,
proto_tree *fh_tree, int length_id, int trailer_id,
int fcs_len)
{
tvbuff_t *volatile next_tvb;
tvbuff_t *volatile trailer_tvb;
volatile unsigned long exception = 0;
if (fh_tree)
proto_tree_add_uint(fh_tree, length_id, tvb, offset_after_length - 2, 2,
length);
/* Give the next dissector only 'length' number of bytes */
TRY {
next_tvb = tvb_new_subset(tvb, offset_after_length, length, length);
trailer_tvb = tvb_new_subset(tvb, offset_after_length + length, -1, -1);
}
CATCH2(BoundsError, ReportedBoundsError) {
/* Either:
the packet doesn't have "length" bytes worth of
captured data left in it - or it may not even have
"length" bytes worth of data in it, period -
so the "tvb_new_subset()" creating "next_tvb"
threw an exception
or
the packet has exactly "length" bytes worth of
captured data left in it, so the "tvb_new_subset()"
creating "trailer_tvb" threw an exception.
In either case, this means that all the data in the frame
is within the length value, so we give all the data to the
next protocol and have no trailer. */
next_tvb = tvb_new_subset(tvb, offset_after_length, -1, length);
trailer_tvb = NULL;
}
ENDTRY;
/* Dissect the payload either as IPX or as an LLC frame.
Catch BoundsError and ReportedBoundsError, so that if the
reported length of "next_tvb" was reduced by some dissector
before an exception was thrown, we can still put in an item
for the trailer. */
TRY {
if (is_802_2)
call_dissector(llc_handle, next_tvb, pinfo, tree);
else
call_dissector(ipx_handle, next_tvb, pinfo, tree);
}
CATCH(ReportedBoundsError) {
/* Well, somebody threw an exception other than BoundsError.
Remember the exception, so we can rethrow it after adding
the trailer.
We do so just in case adding the trailer *also* throws an
exception.
We don't do so for BoundsError, as that exception means
that dissecting the payload found that the packet was
cut off by a snapshot length before the end of the payload;
the trailer comes after the payload, so that was *definitely*
cut off. */
exception = EXCEPT_CODE;
}
ENDTRY;
if (exception != 0) {
/* Perhaps we'll get another exception from attempting to
dissect the trailer; we already have an exception to
show, so we don't want to show that other exception. */
TRY {
add_ethernet_trailer(fh_tree, trailer_id, tvb, trailer_tvb, fcs_len);
}
CATCH_ALL {
; /* do nothing */
}
ENDTRY;
/* Rethrow the original exception, so the appropriate indication
can be put into the tree. */
THROW(exception);
} else
add_ethernet_trailer(fh_tree, trailer_id, tvb, trailer_tvb, fcs_len);
}
void
proto_reg_handoff_ieee802_3(void)
{
/*
* Get handles for the IPX and LLC dissectors.
*/
ipx_handle = find_dissector("ipx");
llc_handle = find_dissector("llc");
}
|
