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When "proto_tree_add_item()" is used with an FT_STRINGZ and given a 

length (rather than being given -1), the length is, in most cases, the
maximum length of a null-*padded* string, rather than the actual length
of a null-*terminated* string.  Treat it as such - allocate a buffer one
larger than the length (to leave room for a terminating '\0'), and pass
the size of that buffer to "tvb_get_nstringz0()".  (Otherwise, in those
cases, the last character of the string is chopped off.)

Allow "proto_tree_add_string()" to add FT_STRINGZ items to the protocol
tree, as well as FT_STRING items.

In "alloc_field_info()", if we're passed a length of -1 and the field is
an FT_STRINGZ, don't make the length be the length remaining in the
tvbuff; that way, you *can* use a length of -1 in
"proto_tree_add_item()" for an FT_STRINGZ item, and have it get the
actual length by looking for the terminating '\0'.

(We might want to distinguish between null-terminated and null-padded
strings, e.g. with an FT_STRINGZPAD type.  Null-terminated strings
rarely, if ever, have a specified length; the length is found by
scanning for the terminating '\0'.  Null-padded strings presumably
always have a specified length, which is the length to which the string
is padded.)

svn path=/trunk/; revision=7784
This commit is contained in:
Guy Harris 2003-06-04 21:51:54 +00:00
parent dd6f38957b
commit aa1c605ba3
1 changed files with 66 additions and 23 deletions
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89
epan/proto.c
View File

@ -1,7 +1,7 @@
/* proto.c
* Routines for protocol tree
*
* $Id: proto.c,v 1.86 2003/05/19 03:23:12 gerald Exp $
* $Id: proto.c,v 1.87 2003/06/04 21:51:54 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
@ -699,6 +699,15 @@ proto_tree_add_item(proto_tree *tree, int hfindex, tvbuff_t *tvb,
case FT_STRINGZ:
if (length != 0) { /* XXX - Should we throw an exception instead? */
/* Instead of calling proto_item_set_len(),
* since we don't yet have a proto_item, we
* set the field_info's length ourselves.
*
* XXX - our caller can't use that length to
* advance an offset unless they arrange that
* there always be a protocol tree into which
* we're putting this item.
*/
if (length == -1) {
/* This can throw an exception */
length = tvb_strsize(tvb, start);
@ -710,14 +719,23 @@ proto_tree_add_item(proto_tree *tree, int hfindex, tvbuff_t *tvb,
new_fi->length = length;
}
else {
/* In this case, length signifies maximum length. */
/* In this case, length signifies
* maximum length. That does not
* include the trailing '\0'; we
* assume this is null-padded,
* not null-terminated, so we need
* a buffer of length length+1,
* with the extra 1 for the trailing
* '\0'. */
/* This g_strdup'ed memory is freed in proto_tree_free_node() */
string = g_malloc(length);
/* This g_strdup'ed memory is freed
* in proto_tree_free_node() */
string = g_malloc(length + 1);
CLEANUP_PUSH(g_free, string);
found_length = tvb_get_nstringz0(tvb, start, length, string);
found_length = tvb_get_nstringz0(tvb,
start, length + 1, string);
CLEANUP_POP;
new_fi->length = found_length + 1;
@ -731,17 +749,24 @@ proto_tree_add_item(proto_tree *tree, int hfindex, tvbuff_t *tvb,
n = get_uint_value(tvb, start, length, little_endian);
proto_tree_set_string_tvb(new_fi, tvb, start + length, n);
/* Instead of calling proto_item_set_len(), since we don't yet
* have a proto_item, we set the field_info's length ourselves. */
/* Instead of calling proto_item_set_len(), since we
* don't yet have a proto_item, we set the
* field_info's length ourselves.
*
* XXX - our caller can't use that length to
* advance an offset unless they arrange that
* there always be a protocol tree into which
* we're putting this item.
*/
new_fi->length = n + length;
break;
default:
g_error("new_fi->hfinfo->type %d (%s) not handled\n",
new_fi->hfinfo->type,
ftype_name(new_fi->hfinfo->type));
g_assert_not_reached();
break;
}
/* Don't add new node to proto_tree until now so that any exceptions
@ -750,13 +775,13 @@ proto_tree_add_item(proto_tree *tree, int hfindex, tvbuff_t *tvb,
CLEANUP_POP;
/* If the proto_tree wants to keep a record of this finfo
* for quick lookup, then record it. */
hash = PTREE_DATA(tree)->interesting_hfids;
ptrs = g_hash_table_lookup(hash, GINT_TO_POINTER(hfindex));
if (ptrs) {
g_ptr_array_add(ptrs, new_fi);
}
/* If the proto_tree wants to keep a record of this finfo
* for quick lookup, then record it. */
hash = PTREE_DATA(tree)->interesting_hfids;
ptrs = g_hash_table_lookup(hash, GINT_TO_POINTER(hfindex));
if (ptrs) {
g_ptr_array_add(ptrs, new_fi);
}
return pi;
}
@ -1199,7 +1224,7 @@ proto_tree_set_uint64_tvb(field_info *fi, tvbuff_t *tvb, gint start, gboolean li
proto_tree_set_uint64(fi, tvb_get_ptr(tvb, start, 8), little_endian);
}
/* Add a FT_STRING to a proto_tree. Creates own copy of string,
/* Add a FT_STRING or FT_STRINGZ to a proto_tree. Creates own copy of string,
* and frees it when the proto_tree is destroyed. */
proto_item *
proto_tree_add_string(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
@ -1213,7 +1238,7 @@ proto_tree_add_string(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
return (NULL);
hfinfo = proto_registrar_get_nth(hfindex);
g_assert(hfinfo->type == FT_STRING);
g_assert(hfinfo->type == FT_STRING || hfinfo->type == FT_STRINGZ);
pi = proto_tree_add_pi(tree, hfindex, tvb, start, &length, &new_fi);
proto_tree_set_string(new_fi, value, FALSE);
@ -1828,14 +1853,32 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
* that, if we throw an exception while dissecting, it
* has what is probably the right value.
*
* For FT_STRINGZ, it means "the string is null-terminated,
* not null-padded; set the length to the actual length
* of the string", and if the tvbuff if short, we just
* throw an exception.
*
* It's not valid for any other type of field.
*/
g_assert(hfinfo->type == FT_PROTOCOL ||
hfinfo->type == FT_NONE ||
hfinfo->type == FT_BYTES ||
hfinfo->type == FT_STRING ||
hfinfo->type == FT_STRINGZ);
*length = tvb_ensure_length_remaining(tvb, start);
switch (hfinfo->type) {
case FT_PROTOCOL:
case FT_NONE:
case FT_BYTES:
case FT_STRING:
*length = tvb_ensure_length_remaining(tvb, start);
break;
case FT_STRINGZ:
/*
* Leave the length as -1, so our caller knows
* it was -1.
*/
break;
default:
g_assert_not_reached();
}
}
fi = g_mem_chunk_alloc(gmc_field_info);