TWAMP: Fix packets changing type in wireshark GUI

Since the type detection runs with every click, depending on the order
packets are selected their type can change.  With this change the type
detection is run only once during the first pass through the packet list
and the results are saved for later use.

Change-Id: Ie0b16c4b6e3372fcf72a246987fe7f23bc33fa14
Reviewed-on: https://code.wireshark.org/review/25987
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, 71 insertions, 70 deletions

diff --git a/epan/dissectors/packet-twamp.c b/epan/dissectors/packet-twamp.c
index b67c0ded19..5920172a84 100644
--- a/epan/dissectors/packet-twamp.c
+++ b/epan/dissectors/packet-twamp.c
@@ -236,83 +236,84 @@ dissect_twamp_control(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void
     if ((cp = (twamp_control_packet_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_twamp_control, 0)) == NULL) {
         cp = wmem_new0(wmem_file_scope(), twamp_control_packet_t);
         p_add_proto_data(wmem_file_scope(), pinfo, proto_twamp_control, 0, cp);
-    }
-    /* detect state */
-    if (pinfo->fd->num == ct->first_data_frame) {
-        ct->last_state = CONTROL_STATE_GREETING;
-    } else if (ct->last_state == CONTROL_STATE_GREETING) {
-        ct->last_state = CONTROL_STATE_SETUP_RESPONSE;
-    } else if (ct->last_state == CONTROL_STATE_SETUP_RESPONSE) {
-        ct->last_state = CONTROL_STATE_SERVER_START;
-    } else if (ct->last_state == CONTROL_STATE_SERVER_START) {
-        ct->last_state = CONTROL_STATE_REQUEST_SESSION;
-        sender_port = tvb_get_ntohs(tvb, 12);
-        receiver_port = tvb_get_ntohs(tvb, 14);
-        /* try to find session from past visits */
-        if ((list = g_slist_find_custom(ct->sessions, &sender_port,
-                (GCompareFunc) find_twamp_session_by_sender_port)) == NULL) {
-            session = (twamp_session_t *) g_malloc0(sizeof(twamp_session_t));
-            session->sender_port = sender_port;
-            session->receiver_port = receiver_port;
-            session->accepted = 0;
-            ipvn = tvb_get_guint8(tvb, 1) & 0x0F;
-
-            if (ipvn == 6) {
-                tvb_get_ipv6(tvb, 16, (struct e_in6_addr*) &session->sender_address);
-                tvb_get_ipv6(tvb, 32, (struct e_in6_addr*) &session->receiver_address);
-
-            } else {
-                session->sender_address[0] = tvb_get_ipv4(tvb, 16);
-                session->receiver_address[0] = tvb_get_ipv4(tvb, 32);
-            }
-            /*
-                * If ip addresses not specified in control protocol, we have to choose from IP header.
-                * It is a design decision by TWAMP and we need that ports for identifying future UDP conversations
-                */
-            if (session->sender_address[0] == 0) {
-                memcpy(&session->sender_address[0], pinfo->src.data, pinfo->src.len);
-            }
-            if (session->receiver_address[0] == 0) {
-                memcpy(&session->receiver_address[0], pinfo->dst.data, pinfo->dst.len);
-            }
-            session->padding = tvb_get_ntohl(tvb, 64);
-            ct->sessions = g_slist_append(ct->sessions, session);
-        }
-    } else if (ct->last_state == CONTROL_STATE_REQUEST_SESSION) {
-        ct->last_state = CONTROL_STATE_ACCEPT_SESSION;
-        accept = tvb_get_guint8(tvb, 0);
-        if (accept == TWAMP_SESSION_ACCEPT_OK) {
-            receiver_port = tvb_get_ntohs(tvb, 2);
-
-            if ((list = g_slist_find_custom(ct->sessions, NULL,
-                    (GCompareFunc) find_twamp_session_by_first_accept_waiting)) == NULL) {
-                return 0;
+
+        /* detect state */
+        if (pinfo->fd->num == ct->first_data_frame) {
+            ct->last_state = CONTROL_STATE_GREETING;
+        } else if (ct->last_state == CONTROL_STATE_GREETING) {
+            ct->last_state = CONTROL_STATE_SETUP_RESPONSE;
+        } else if (ct->last_state == CONTROL_STATE_SETUP_RESPONSE) {
+            ct->last_state = CONTROL_STATE_SERVER_START;
+        } else if (ct->last_state == CONTROL_STATE_SERVER_START) {
+            ct->last_state = CONTROL_STATE_REQUEST_SESSION;
+            sender_port = tvb_get_ntohs(tvb, 12);
+            receiver_port = tvb_get_ntohs(tvb, 14);
+            /* try to find session from past visits */
+            if ((list = g_slist_find_custom(ct->sessions, &sender_port,
+                    (GCompareFunc) find_twamp_session_by_sender_port)) == NULL) {
+                session = (twamp_session_t *) g_malloc0(sizeof(twamp_session_t));
+                session->sender_port = sender_port;
+                session->receiver_port = receiver_port;
+                session->accepted = 0;
+                ipvn = tvb_get_guint8(tvb, 1) & 0x0F;
+
+                if (ipvn == 6) {
+                    tvb_get_ipv6(tvb, 16, (struct e_in6_addr*) &session->sender_address);
+                    tvb_get_ipv6(tvb, 32, (struct e_in6_addr*) &session->receiver_address);
+
+                } else {
+                    session->sender_address[0] = tvb_get_ipv4(tvb, 16);
+                    session->receiver_address[0] = tvb_get_ipv4(tvb, 32);
+                }
+                /*
+                 * If ip addresses not specified in control protocol, we have to choose from IP header.
+                 * It is a design decision by TWAMP and we need that ports for identifying future UDP conversations
+                 */
+                if (session->sender_address[0] == 0) {
+                    memcpy(&session->sender_address[0], pinfo->src.data, pinfo->src.len);
+                }
+                if (session->receiver_address[0] == 0) {
+                    memcpy(&session->receiver_address[0], pinfo->dst.data, pinfo->dst.len);
+                }
+                session->padding = tvb_get_ntohl(tvb, 64);
+                ct->sessions = g_slist_append(ct->sessions, session);
             }
-            session = (twamp_session_t*) list->data;
-            session->receiver_port = receiver_port;
+        } else if (ct->last_state == CONTROL_STATE_REQUEST_SESSION) {
+            ct->last_state = CONTROL_STATE_ACCEPT_SESSION;
+            accept = tvb_get_guint8(tvb, 0);
+            if (accept == TWAMP_SESSION_ACCEPT_OK) {
+                receiver_port = tvb_get_ntohs(tvb, 2);
+
+                if ((list = g_slist_find_custom(ct->sessions, NULL,
+                        (GCompareFunc) find_twamp_session_by_first_accept_waiting)) == NULL) {
+                    return 0;
+                }
+                session = (twamp_session_t*) list->data;
+                session->receiver_port = receiver_port;
 
-            cp->conversation = find_conversation(pinfo->fd->num, &pinfo->dst, &pinfo->src, ENDPOINT_UDP,
-                    session->sender_port, session->receiver_port, 0);
-            if (cp->conversation == NULL /*|| cp->conversation->dissector_handle != twamp_test_handle*/) {
-                cp->conversation = conversation_new(pinfo->fd->num, &pinfo->dst, &pinfo->src, ENDPOINT_UDP,
+                cp->conversation = find_conversation(pinfo->fd->num, &pinfo->dst, &pinfo->src, ENDPOINT_UDP,
                         session->sender_port, session->receiver_port, 0);
-                if (cp->conversation) {
-                    /* create conversation specific data for test sessions */
-                    conversation_add_proto_data(cp->conversation, proto_twamp_test, session);
-                    conversation_set_dissector(cp->conversation, twamp_test_handle);
+                if (cp->conversation == NULL /*|| cp->conversation->dissector_handle != twamp_test_handle*/) {
+                    cp->conversation = conversation_new(pinfo->fd->num, &pinfo->dst, &pinfo->src, ENDPOINT_UDP,
+                            session->sender_port, session->receiver_port, 0);
+                    if (cp->conversation) {
+                        /* create conversation specific data for test sessions */
+                        conversation_add_proto_data(cp->conversation, proto_twamp_test, session);
+                        conversation_set_dissector(cp->conversation, twamp_test_handle);
+                    }
                 }
             }
+        } else if (ct->last_state == CONTROL_STATE_ACCEPT_SESSION) {
+            ct->last_state = CONTROL_STATE_START_SESSIONS;
+        } else if (ct->last_state == CONTROL_STATE_START_SESSIONS) {
+            ct->last_state = CONTROL_STATE_START_SESSIONS_ACK;
+        } else if (ct->last_state == CONTROL_STATE_START_SESSIONS_ACK) {
+            ct->last_state = CONTROL_STATE_STOP_SESSIONS;
+        } else {
+            /* response */
         }
-    } else if (ct->last_state == CONTROL_STATE_ACCEPT_SESSION) {
-        ct->last_state = CONTROL_STATE_START_SESSIONS;
-    } else if (ct->last_state == CONTROL_STATE_START_SESSIONS) {
-        ct->last_state = CONTROL_STATE_START_SESSIONS_ACK;
-    } else if (ct->last_state == CONTROL_STATE_START_SESSIONS_ACK) {
-        ct->last_state = CONTROL_STATE_STOP_SESSIONS;
-    } else {
-        /* response */
+        cp->state = ct->last_state;
     }
-    cp->state = ct->last_state;
 
     col_set_str(pinfo->cinfo, COL_PROTOCOL, "TWAMP-Control");