WIP: rlcmac: Support dissecting LLC frames in rlcmac data blocks

epan/dissectors/packet-gsm_rlcmac.c

@@ -49,6 +49,7 @@ void proto_reg_handoff_gsm_rlcmac(void);
 
 static dissector_handle_t lte_rrc_dl_dcch_handle = NULL;
 static dissector_handle_t rrc_irat_ho_to_utran_cmd_handle = NULL;
+static dissector_handle_t llc_handle = NULL;
 
 /* private typedefs */
 typedef struct
@@ -8585,6 +8586,7 @@ static guint8 dissect_gprs_data_segments(tvbuff_t *tvb, packet_info *pinfo, prot
         data_tvb = tvb_new_subset_length(tvb, octet_offset, blk_length - octet_offset);
         call_data_dissector(data_tvb, pinfo, subtree);
         octet_offset = blk_length;
+        /* TODO: here store data_tvb for later */
         break;
 
       case 63:
@@ -8611,7 +8613,14 @@ static guint8 dissect_gprs_data_segments(tvbuff_t *tvb, packet_info *pinfo, prot
                                  "data segment: LI[%d]=%d indicates: (Last segment of) LLC frame (%d octets)",
                                  i, li, li);
         data_tvb = tvb_new_subset_length(tvb, octet_offset, li);
-        call_data_dissector(data_tvb, pinfo, subtree);
+        if(data_tvb) {
+            if (llc_handle) {
+                /* TODO: here used data_tvb previously stored and append current data_tvb to it. */
+                call_dissector(llc_handle, data_tvb, pinfo, subtree);
+            } else {
+                call_data_dissector(data_tvb, pinfo, subtree);
+            }
+        }
         octet_offset += li;
         break;
     }
@@ -8628,6 +8637,7 @@ static guint8 dissect_gprs_data_segments(tvbuff_t *tvb, packet_info *pinfo, prot
                                "data segment: LI not present: \n The Upper Layer PDU in the current RLC data block either fills the current RLC data block precisely \nor continues in the following in-sequence RLC data block");
       data_tvb = tvb_new_subset_length(tvb, octet_offset, blk_length - octet_offset);
       call_data_dissector(data_tvb, pinfo, subtree);
+      /* TODO: here store data_tvb for later */
      } else {
       proto_tree_add_bytes_item(tree, hf_padding, tvb, octet_offset, blk_length - octet_offset, ENC_BIG_ENDIAN, NULL, NULL, NULL);
      }
@@ -8730,7 +8740,14 @@ static guint16 dissect_egprs_data_segments(tvbuff_t *tvb, packet_info *pinfo, pr
                                  "data segment: LI[%d]=%d indicates: (Last segment of) LLC frame (%d octets)",
                                  i, li, li);
         data_tvb = tvb_new_subset_length(tvb, octet_offset, li);
-        call_data_dissector(data_tvb, pinfo, subtree);
+        if(data_tvb) {
+            if (llc_handle) {
+                /* TODO: here used data_tvb previously stored and append current data_tvb to it. */
+                call_dissector(llc_handle, data_tvb, pinfo, subtree);
+            } else {
+                call_data_dissector(data_tvb, pinfo, subtree);
+            }
+        }
         octet_offset += li;
         break;
     }
@@ -18630,6 +18647,7 @@ void proto_reg_handoff_gsm_rlcmac(void)
 {
   lte_rrc_dl_dcch_handle = find_dissector("lte_rrc.dl_dcch");
   rrc_irat_ho_to_utran_cmd_handle = find_dissector("rrc.irat.ho_to_utran_cmd");
+  llc_handle = find_dissector("llcgprs");
 }
 
 /*