Dear all,
I forgot to say that
gboolean checksum_correct;
is defined and the definition of the checksum routine is
static gboolean
sctp_checksum_correct(tvbuff_t *tvb, guint orig_checksum)
{
guint length;
length = tvb_length(tvb);
if (orig_checksum == sctp_adler_32(tvb_get_ptr(tvb, 0, length),
length))
return TRUE;
else
return FALSE;
}
Maybe that helps.
Best regards
Michael
On Tuesday, December 18, 2001, at 08:46 PM, Michael Tuexen wrote:
Dear all,
thank you very uch for your help. I tried the following:
proto_tree_add_uint(sctp_tree, hf_sctp_source_port, tvb,
SOURCE_PORT_OFFSET, SOURCE_PORT_LENGTH, source_port);
proto_tree_add_uint(sctp_tree, hf_sctp_destination_port, tvb,
DESTINATION_PORT_OFFSET, DESTINATION_PORT_LENGTH, destination_port);
proto_tree_add_uint(sctp_tree, hf_sctp_verification_tag, tvb,
VERIFICATION_TAG_OFFSET, VERIFICATION_TAG_LENGTH, verification_tag);
checksum_correct = sctp_checksum_correct(tvb, checksum);
proto_tree_add_uint_format(sctp_tree, hf_sctp_checksum, tvb,
CHECKSUM_OFFSET, CHECKSUM_LENGTH, checksum, "Adler-32 checksum: 0x%08x
(%u)", checksum, checksum_correct);
proto_tree_add_item(sctp_tree, hf_sctp_checksum_correct, tvb,
CHECKSUM_OFFSET, CHECKSUM_LENGTH, checksum_correct);
...
{ &hf_sctp_checksum_correct,
{ "Adler-32 checksum correct", "sctp.checksum_correct",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"", HFILL }
},
The %u is only for debugging. tethereal shows:
Stream Control Transmission Protocol
Source port: 2907
Destination port: 2907
Verification tag: 0x29400a52
Adler-32 checksum: 0x36010394 (0)
Adler-32 checksum correct: True
SACK chunk acknowledging TSN 604091652 and reporting 0 gaps and 0
duplicate TSNs
On one line this means that checksum_correct is 0, which means that the
checksum is incorrect,
on the next line it is TRUE. Hmm. That is why I'm asking how to write
the stuff.
Any hints?
Best regards
Michael
On Tuesday, December 18, 2001, at 07:54 PM, Guy Harris wrote:
Dear Guy, Dear all,
"Guy" is a member of "all", so it's not necessary to CC either my home
or my work e-mail address on mail to "ethereal-dev" or
"ethereal-users".
Currently I'm calculating the checksum in the dissector and display it
with proto_tree_add_uint_format. I'm trying also to insert in the tree
a boolean variable with proto_tree_add_item (or the hidden version)
and
provide a boolean variable as a parameter, which describes oof the
checksum
is right. But this bit is not part of the packet, of course. How can I
do it?
The same way the IP dissector does it:
if (ipsum == 0) {
proto_tree_add_uint_format(ip_tree, hf_ip_checksum, tvb,
offset + 10, 2, iph.ip_sum,
"Header checksum: 0x%04x (correct)", iph.ip_sum);
}
else {
proto_tree_add_item_hidden(ip_tree, hf_ip_checksum_bad, tvb,
offset + 10, 2, TRUE);
proto_tree_add_uint_format(ip_tree, hf_ip_checksum, tvb,
offset + 10, 2, iph.ip_sum,
"Header checksum: 0x%04x (incorrect, should be 0x%04x)",
iph.ip_sum, in_cksum_shouldbe(iph.ip_sum, ipsum));
}
...
static hf_register_info hf[] = {
...
{ &hf_ip_checksum,
{ "Header checksum", "ip.checksum", FT_UINT16, BASE_HEX,
NULL, 0x0, "", HFILL }},
{ &hf_ip_checksum_bad,
{ "Bad Header checksum", "ip.checksum_bad", FT_BOOLEAN,
BASE_NONE, NULL, 0x0, "", HFILL }},
...
};
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