FPP: Make dissector directionally aware

The IEEE 802.3br dissector does good work figuring out when a frame is
preempted by another, in the same direction, and reassemble the continuation
into a proper Ethernet frame. But when, at the same time, a frame appears in
the other direction, not unheard of in a full duplex link, the reassembly is
thrown in turmoil.
This change makes the reassembly directionally aware, so that preemptions,
either way and even simultanious, can be distinguised as long as the
direction of the frame is known.

Bug: 16470
Change-Id: Ic99353c1b95238e0d63c4cd14cd454d09e3675cc
Reviewed-on: https://code.wireshark.org/review/36731
Reviewed-by: Jaap Keuter <jaap.keuter@xs4all.nl>
Petri-Dish: Jaap Keuter <jaap.keuter@xs4all.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 10 insertions, 12 deletions

diff --git a/epan/dissectors/packet-fpp.c b/epan/dissectors/packet-fpp.c
index e588db3786..f13cd028f8 100644
--- a/epan/dissectors/packet-fpp.c
+++ b/epan/dissectors/packet-fpp.c
@@ -88,8 +88,6 @@ static const fragment_items fpp_frag_items = {
 #define FPP_PREAMBLE_LENGTH		8
 #define FPP_CRC_LENGTH			4
 
-#define FPP_CONVERSATION_ID		0
-
 typedef enum {
 	FPP_Packet_Expess,
 	FPP_Packet_Verify,
@@ -302,7 +300,7 @@ drop_conversation(conversation_t *conv) {
 static void
 drop_fragments(packet_info *pinfo) {
 	tvbuff_t *tvbuf;
-	tvbuf = fragment_delete(&fpp_reassembly_table, pinfo, 1, NULL);
+	tvbuf = fragment_delete(&fpp_reassembly_table, pinfo, pinfo->p2p_dir, NULL);
 	if (tvbuf != NULL) {
 		tvb_free(tvbuf);
 	}
@@ -328,9 +326,9 @@ dissect_preemption(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32
 	conversation_t *conv;
 	fpp_ctx_t *ctx;
 
-	conv = find_conversation_by_id(pinfo->num, ENDPOINT_NONE, FPP_CONVERSATION_ID, 0);
+	conv = find_conversation_by_id(pinfo->num, ENDPOINT_NONE, pinfo->p2p_dir, 0);
 	if (!conv) {
-		conv = conversation_new_by_id(pinfo->num, ENDPOINT_NONE, FPP_CONVERSATION_ID, 0);
+		conv = conversation_new_by_id(pinfo->num, ENDPOINT_NONE, pinfo->p2p_dir, 0);
 	}
 
 	/* Create a tree for the preamble. */
@@ -377,7 +375,7 @@ dissect_preemption(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32
 			}
 
 			fragment_add_check(&fpp_reassembly_table,
-								tvb, FPP_PREAMBLE_LENGTH, pinfo, 1, NULL,
+								tvb, FPP_PREAMBLE_LENGTH, pinfo, pinfo->p2p_dir, NULL,
 								0, frag_size, TRUE);
 
 			set_address_tvb(&pinfo->dl_dst, AT_ETHER, 6, tvb, 8);
@@ -405,7 +403,7 @@ dissect_preemption(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32
 				if ((ctx) && (ctx->preemption) && (ctx->frame_cnt == smd1) && (frag_cnt_next(ctx->frag_cnt) == smd2)) {
 					fpp_pdata_t *fpp_pdata = wmem_new(wmem_file_scope(), fpp_pdata_t);
 					fpp_pdata->offset = ctx->size;
-					p_add_proto_data(wmem_file_scope(), pinfo, proto_fpp, 0, fpp_pdata);
+					p_add_proto_data(wmem_file_scope(), pinfo, proto_fpp, pinfo->p2p_dir, fpp_pdata);
 
 					ctx->size += frag_size;
 					ctx->frag_cnt = smd2;
@@ -415,10 +413,10 @@ dissect_preemption(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32
 				}
 			}
 
-			fpp_pdata_t *fpp_pdata = (fpp_pdata_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_fpp, 0);
+			fpp_pdata_t *fpp_pdata = (fpp_pdata_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_fpp, pinfo->p2p_dir);
 			if (fpp_pdata) {
 				fragment_add_check(&fpp_reassembly_table,
-									tvb, FPP_PREAMBLE_LENGTH, pinfo, 1, NULL,
+									tvb, FPP_PREAMBLE_LENGTH, pinfo, pinfo->p2p_dir, NULL,
 									fpp_pdata->offset, frag_size, TRUE);
 			} else {
 				drop_fragments(pinfo);
@@ -436,18 +434,18 @@ dissect_preemption(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32
 				if ((ctx) && (ctx->preemption) && (ctx->frame_cnt == smd1) && (frag_cnt_next(ctx->frag_cnt) == smd2)) {
 					fpp_pdata_t *fpp_pdata = wmem_new(wmem_file_scope(), fpp_pdata_t);
 					fpp_pdata->offset = ctx->size;
-					p_add_proto_data(wmem_file_scope(), pinfo, proto_fpp, 0, fpp_pdata);
+					p_add_proto_data(wmem_file_scope(), pinfo, proto_fpp, pinfo->p2p_dir, fpp_pdata);
 				}
 
 				drop_conversation(conv);
 			}
 
-			fpp_pdata_t *fpp_pdata = (fpp_pdata_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_fpp, 0);
+			fpp_pdata_t *fpp_pdata = (fpp_pdata_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_fpp, pinfo->p2p_dir);
 			if (fpp_pdata) {
 				save_fragmented = pinfo->fragmented;
 				pinfo->fragmented = TRUE;
 				frag_data = fragment_add_check(&fpp_reassembly_table,
-												tvb, FPP_PREAMBLE_LENGTH, pinfo, 1, NULL,
+												tvb, FPP_PREAMBLE_LENGTH, pinfo, pinfo->p2p_dir, NULL,
 												fpp_pdata->offset, frag_size, FALSE);
 				// Attempt reassembly.
 				new_tvb = process_reassembled_data(tvb, FPP_PREAMBLE_LENGTH, pinfo,