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From Steve Karg: 

1) BACnet signed values were being decoded incorrectly for negative
values since BACnet tries to be clever and minimizes the number of bytes
sent on the wire and drops the leading FF on negative values.  For
example, -200 is passed as FF 38 on the wire, but would display as 65336.
2) Since the BACnet unsigned values were decoded using a 64-bit entity,
I changed the decoding such that allows all 8 bytes to be decoded.  The
function can now decode 5, 6, and 7 byte values.
3) Corrected warning about signed/unsigned in a pointer parameter.

svn path=/trunk/; revision=17877
This commit is contained in:
Jaap Keuter 2006-04-16 22:03:04 +00:00
parent f45378f3bc
commit 12de0d5145
1 changed files with 44 additions and 24 deletions
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68
epan/dissectors/packet-bacapp.c
View File

@ -1339,32 +1339,52 @@ fUnsigned32 (tvbuff_t *tvb, guint offset, guint32 lvt, guint32 *val)
static gboolean
fUnsigned64 (tvbuff_t *tvb, guint offset, guint32 lvt, guint64 *val)
{
gboolean valid = TRUE;
gboolean valid = FALSE;
gint64 value = 0;
guint8 data, i;
switch (lvt) {
case 1:
*val = tvb_get_guint8(tvb, offset);
break;
case 2:
*val = tvb_get_ntohs(tvb, offset);
break;
case 3:
*val = tvb_get_ntoh24(tvb, offset);
break;
case 4:
*val = tvb_get_ntohl(tvb, offset);
break;
case 8:
*val = tvb_get_ntoh64(tvb, offset);
break;
default:
valid = FALSE;
break;
if (lvt && (lvt <= 8)) {
valid = TRUE;
data = tvb_get_guint8(tvb, offset);
for (i = 0; i < lvt; i++) {
data = tvb_get_guint8(tvb, offset+i);
value = (value << 8) + data;
}
*val = value;
}
return valid;
}
/* BACnet Signed Value uses 2's compliment notation, but with a twist:
All signed integers shall be encoded in the smallest number of octets
possible. That is, the first octet of any multi-octet encoded value
shall not be X'00' if the most significant bit (bit 7) of the second
octet is 0, and the first octet shall not be X'FF' if the most
significant bit of the second octet is 1. ASHRAE-135-2004-20.2.5 */
static gboolean
fSigned64 (tvbuff_t *tvb, guint offset, guint32 lvt, gint64 *val)
{
gboolean valid = FALSE;
gint64 value = 0;
guint8 data, i;
/* we can only handle 7 bytes for a 64-bit value due to signed-ness */
if (lvt && (lvt <= 7)) {
valid = TRUE;
data = tvb_get_guint8(tvb, offset);
if ((data & 0x80) != 0)
value = (-1 << 8) | data;
for (i = 1; i < lvt; i++) {
data = tvb_get_guint8(tvb, offset+i);
value = (value << 8) + data;
}
*val = value;
}
return valid;
}
static guint
fTagHeaderTree (tvbuff_t *tvb, proto_tree *tree, guint offset,
guint8 *tag_no, guint8* tag_info, guint32 *lvt)
@ -1574,7 +1594,7 @@ fEnumeratedTag (tvbuff_t *tvb, proto_tree *tree, guint offset, const gchar *labe
static guint
fSignedTag (tvbuff_t *tvb, proto_tree *tree, guint offset, const gchar *label)
{
guint64 val = 0;
gint64 val = 0;
guint8 tag_no, tag_info;
guint32 lvt;
guint tag_len;
@ -1582,9 +1602,9 @@ fSignedTag (tvbuff_t *tvb, proto_tree *tree, guint offset, const gchar *label)
proto_tree *subtree;
tag_len = fTagHeader (tvb, offset, &tag_no, &tag_info, &lvt);
if (fUnsigned64 (tvb, offset + tag_len, lvt, &val))
if (fSigned64 (tvb, offset + tag_len, lvt, &val))
ti = proto_tree_add_text(tree, tvb, offset, lvt+tag_len,
"%s(Signed) %" PRId64, label, (gint64) val);
"%s(Signed) %" PRId64, label, val);
else
ti = proto_tree_add_text(tree, tvb, offset, lvt+tag_len,
"%s - %u octets (Signed)", label, lvt);
@ -2136,7 +2156,7 @@ fPropertyIdentifier (tvbuff_t *tvb, proto_tree *tree, guint offset)
propertyIdentifier = 0; /* global Variable */
tag_len = fTagHeader (tvb, offset, &tag_no, &tag_info, &lvt);
if (fUnsigned32 (tvb, offset+tag_len, lvt, &propertyIdentifier))
if (fUnsigned32 (tvb, offset+tag_len, lvt, (guint32 *)&propertyIdentifier))
ti = proto_tree_add_text(tree, tvb, offset, lvt+tag_len,
"property Identifier: %s",
val_to_split_str(propertyIdentifier, 512,