Fix the FCS handling.

All the complicated stuff to see whether the captured data includes all
of, some of, or none of the FCS is necessary, and should not have been
removed.  The previous code would sometimes dissect packet data at the
end as both payload *and* FCS.

This also means that the decryption code doesn't have to worry about the
FCS, and expects the payload handed to it *not* to have the FCS.  Update
callers to handle that.

This puts back the changes from
e4d3916530aed332fcb39d4017e633bd51c4277c, for which the comment was:

    Clean up the way we handle the FCS.

    For the "802.15.4 with FCS" link-layer type, strip what FCS we find,
    if any, off and use that new tvbuff for all dissection except for
    checking and dissection of the FCS itself.

    For the "802.15.4 without FCS" link-layer type, don't fake an
    uncaptured FCS by increasing the reported length, just use the
    tvbuff as is.

    This means we handle 802.15.4 the same way we handle other
    link-layer types where the FCS might, or might not, appear as
    part of the captured data.

"Handling stuff at the ends of packets is hard, let's go shopping!"

Change-Id: Iaf3e8392efec9d1c35f73966e22f2a3ae91317a1
Reviewed-on: https://code.wireshark.org/review/32254
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 0 insertions, 2 deletions

diff --git a/epan/dissectors/packet-wisun.c b/epan/dissectors/packet-wisun.c
index 5465faeee7..4cb6bd5fd8 100644
--- a/epan/dissectors/packet-wisun.c
+++ b/epan/dissectors/packet-wisun.c
@@ -1069,8 +1069,6 @@ static int dissect_wisun_netricity_sc(tvbuff_t *tvb, packet_info *pinfo, proto_t
 
         pinfo->fragmented = save_fragmented;
     } else {
-        // the decryption function expects the tvb with the FCS as part of the reported length
-        frame = tvb_new_subset_length_caplen(frame, 0, -1, tvb_reported_length(frame)+ieee802154_fcs_len);
         tvbuff_t *payload = ieee802154_decrypt_payload(frame, mhr_len, pinfo, ieee802154_tree, packet);
         if (payload) {
             guint pie_size = ieee802154_dissect_payload_ies(payload, pinfo, ieee802154_tree, packet);