mptcp: Correctly find mappings and reinjections

- removed mptcp.duplicated_dsn in favor of mptcp.reinjection_of/mptcp.reinjected_in
reinjected_in lists the packets where the DSN was later reinjected in.
reinjection_of lists the packets in which this DSN was already transmitted.
- There was a bug where the max_edge property of the interval tree was not
correctly updated. Right now wireshark gives a dsn for every TCP frame (even
empty packets).
- Now displays mappings only for packets with data (seglen > 0).
- Renamed dsn_map to dsn2packet_map and mappings to ssn2dsn_mappings.
- precises the complexity of enabling certain MPTCP options so that the user
better understand their impact on processing speed.

Change-Id: I24adc3161021b7f6a084763a74dc580f1c1f2c2e
Reviewed-on: https://code.wireshark.org/review/28326
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 8 insertions, 7 deletions

diff --git a/epan/dissectors/packet-tcp.h b/epan/dissectors/packet-tcp.h
index 7f84351ade..c1811fa049 100644
--- a/epan/dissectors/packet-tcp.h
+++ b/epan/dissectors/packet-tcp.h
@@ -257,15 +257,16 @@ struct mptcp_subflow {
 	guint8 address_id;   /* sent during an MP_JOIN */
 
 
-	/* Attempt to map DSN to packets
-	 * Ideally this was to generate application latency
-	 * each node contains a GSList * ?
-	 * this should be done in tap or 3rd party tools
+	/* map DSN to packets
+	 * Used when looking for reinjections across subflows
 	 */
-	wmem_itree_t *dsn_map;
+	wmem_itree_t *dsn2packet_map;
 
-	/* Map SSN to a DSS mappings, each node registers a mptcp_dss_mapping_t */
-	wmem_itree_t *mappings;
+	/* Map SSN to a DSS mappings
+	 * a DSS can map DSN to SSNs possibily over several packets,
+	 * hence some packets may have been mapped by previous DSS,
+	 * whence the necessity to be able to look for SSN -> DSN */
+	wmem_itree_t *ssn2dsn_mappings;
 	/* meta flow to which it is attached. Helps setting forward and backward meta flow */
 	mptcp_meta_flow_t *meta;
 };