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For protocol tree items of type FT_NONE and FT_PROTOCOL, treat negative 

length values (other than -1) as very large positive values, and for
values larger than the amount of data remaining in the tvbuff, clip the
value to the length of the tvbuff, so that dissectors don't have to
worry about doing that clipping themselves.

svn path=/trunk/; revision=13913
This commit is contained in:
Guy Harris 2005-03-26 03:27:22 +00:00
parent eb1193bfa2
commit 48217e0bee
1 changed files with 30 additions and 3 deletions
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33
epan/proto.c
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@ -2008,6 +2008,8 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
{
header_field_info *hfinfo;
field_info *fi;
gint item_length;
gint length_remaining;
/*
* We only allow a null tvbuff if the item has a zero length,
@ -2017,6 +2019,14 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
PROTO_REGISTRAR_GET_NTH(hfindex, hfinfo);
/*
* XXX - in some protocols, there are 32-bit unsigned length
* fields, so lengths in protocol tree and tvbuff routines
* should really be unsigned. We should have, for those
* field types for which "to the end of the tvbuff" makes sense,
* additional routines that take no length argument and
* add fields that run to the end of the tvbuff.
*/
if (*length == -1) {
/*
* For FT_NONE, FT_PROTOCOL, FT_BYTES, and FT_STRING fields,
@ -2097,10 +2107,27 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
default:
DISSECTOR_ASSERT_NOT_REACHED();
}
item_length = *length;
} else {
if (*length < 0) {
item_length = *length;
if (hfinfo->type == FT_PROTOCOL || hfinfo->type == FT_NONE) {
/*
* These types are for interior nodes of the
* tree, and don't have data associated with
* them; if the length is negative (XXX - see
* above) or goes past the end of the tvbuff,
* cut it short at the end of the tvbuff.
* That way, if this field is selected in
* Ethereal, we don't highlight stuff past
* the end of the data.
*/
length_remaining = tvb_length_remaining(tvb, start);
if (item_length < 0 || length_remaining < item_length)
item_length = length_remaining;
}
if (item_length < 0) {
REPORT_DISSECTOR_BUG(g_strdup_printf("\"%s\" - \"%s\" invalid length: %d (%s:%u)",
hfinfo->name, hfinfo->abbrev, *length,
hfinfo->name, hfinfo->abbrev, item_length,
__FILE__, __LINE__));
}
}
@ -2110,7 +2137,7 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
fi->hfinfo = hfinfo;
fi->start = start;
fi->start+=(tvb)?TVB_RAW_OFFSET(tvb):0;
fi->length = *length;
fi->length = item_length;
fi->tree_type = -1;
fi->flags = 0;
if (!PTREE_DATA(tree)->visible)