Wireshark · Wireshark-dev: [Wireshark-dev] Need Your Support on Reassembling of packets

[Raj sekar <mrajsekar@xxxxxxxxx>]

Hi All,

 

greetings!

 

Iam Developing Custom Dissector and i have almost finished and got stuck in Reassemble of packets.

 

I have been posting question on wireshark website and could not get the solution.

 

PLEASE HELP ME ON THIS !

 

My code is below and do not know whats wrong in this. Reassembly TVB itself not created.

 

I have also posted questions here

https://ask.wireshark.org/questions/38292/reassemble-length

https://ask.wireshark.org/questions/37987/packet-reassembly-not-succesful 

 

Please Help!

 

Thanks!

 

Best Regards,

Raj

 

 

 

guint8 flag,poll,stype,sflag,flag_sel,num_sel,i;
guint16 seq_num_s,seq_num_r;
guint32 rem_length;
guint8 save_fragmented;
coseq_num_st guint32 mte_seqid=0;
coseq_num_st void *data = NULL;
gboolean more_frags=TRUE;
proto_item *frag_tree_item;

			flag = (tvb_get_guint8(next_tvb, offset_payload) & 0x80) >>7 ;   // Bit 8  to check i pdu /s pdu or sseg pdu

            if (flag == 0x00){ // flag "0" is for i-pdu

            poll = (tvb_get_guint8(next_tvb, offset_payload) & 0x40) >>6 ; // Bit 7 poll
            seq_num_s = (tvb_get_ntohs(next_tvb, offset_payload) & 0x3ff0) >>4 ; // 10 Bits are seq_num_s
            offset_payload +=1;
            seq_num_r= (tvb_get_ntohs(next_tvb, offset_payload) & 0x0ffc) >>2 ; // 10 bits are seq_num_r
            offset_payload +=1;
            stype = (tvb_get_guint8(next_tvb, offset_payload) & 0x03) ; // 2 bits LSB are Stype
            offset_payload -=2;

            FT_connPDU_item = proto_tree_add_text(tree, next_tvb, offset_payload, sdu_length, "BCnPDU (Formatted) : Information, I flag = 0x%02x, poll = 0x%02x, seq_num_s = 0x%02x, seq_num_r = 0x%02x ", iflag,poll,seq_num_s,seq_num_r );

            FT_connPDU_tree = proto_item_add_subtree(FT_connPDU_item, ett_FT_BCnPDU);

            proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 1, " sdu_length: %d", sdu_length);

            proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 1, "flag : 0x%02x (%s)", iflag,val_to_str(iflag,true_false_vals,"%s"));

            proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 1, "poll : 0x%02x (%d)", poll,poll);

            proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 2, "seq_num_s : 0x%02x (%d)", seq_num_s,seq_num_s);

            offset_payload +=1;
            sdu_length-=1;

            proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 2, "seq_num_r : 0x%02x (%d)", seq_num_r,seq_num_r);

            offset_payload +=1;

            sdu_length-=1;

            proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 1, "BConseq_num_segType : 0x%02x (%s)", stype,val_to_str(stype,BCn_Seg_Type_vals,"%s"));

            offset_payload +=1;

            sdu_length-=1;

       switch (stype){

			case 0x00: // Continuation of Message

                                        sdu_length+=1;
										rem_length = (guint32) sdu_length;

                                        proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, rem_length , "PDU data : %d", rem_length);

										offset_payload +=rem_length;
                                        sdu_length-=rem_length;

                                        proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 1 , "sdu_length: %d", sdu_length);

                                        save_fragmented = pinfo->fragmented;
                                        pinfo->fragmented = TRUE;

										mte_frag_msg = fragment_add_seq_next(&mte_reassembly_table,next_tvb, offset_payload, pinfo, mte_seqid, NULL, rem_length, more_frags);
                                        pinfo->fragmented = save_fragmented;
                                        col_set_str(pinfo->cinfo, COL_INFO, " mte segment of a reassembled PDU");

                                        if (sdu_length>0){

                                        SIG_PDU(next_tvb, pinfo, tree);

                                                }

									break;

			case 0x01: // Beginning of Message

                                            BCnPDU_stype_item = proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, 1, "%s",val_to_str(stype,BCn_Seg_Type_vals,"%s"));
                                            BCnPDU_stype_tree = proto_item_add_subtree(BCnPDU_stype_item, ett_BCnPDU_stype);

                                            BCnPDU_bom_item = proto_tree_add_text(BCnPDU_stype_tree, next_tvb, offset_payload, 1, "MACSApollLAGS");
                                            BCnPDU_bom_tree = proto_item_add_subtree(BCnPDU_bom_item, ett_BCnPDU_bom);

                                            temp_val = (tvb_get_guint8(next_tvb, offset_payload) & 0x80) >>7 ; // Bit 8 - Flow Control
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 1, "Flow Control : 0x%02x (%s)", temp_val,val_to_str(temp_val, true_false_vals,"%s"));
                                            temp_val = (tvb_get_guint8(next_tvb, offset_payload) & 0x40) >>6 ; // Bit 7 - Reserved l
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 1, "Reserved l : 0x%02x (%d)", temp_val,temp_val);
                                            temp_val = (tvb_get_guint8(next_tvb, offset_payload) & 0x20) >>5 ; // Bit 6 - Expedited
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 1, "Expedited : 0x%02x (%s)", temp_val,val_to_str(temp_val, true_false_vals,"%s"));
                                            temp_val = (tvb_get_guint8(next_tvb, offset_payload) & 0x10) >>4 ; // Bit 5 - OAM PDU Flag
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 1, "OAM PDU Flag : 0x%02x (%s)", temp_val,val_to_str(temp_val, true_false_vals,"%s"));
                                            temp_val = (tvb_get_guint8(next_tvb, offset_payload) & 0x08) >>3 ; // Bit 4 - Reserved 2
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 1, "Reserved 2 : 0x%02x (%d)", temp_val,temp_val);
                                            pl_val = (tvb_get_ntohs(next_tvb, offset_payload) & 0x07ff); // PDU Length - 11 Bits 
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 2, "PDU Length : 0x%02x (%d)", pl_val,pl_val);
                                            pl_val = (guint32)pl_val;
                                            fragment_set_tot_len(&mte_reassembly_table, pinfo,mte_seqid, NULL, pl_val);
                                            offset_payload+=2;
                                            sdu_length+=2;
                                            proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, 1, " sdu_length: %d", sdu_length);
                                            rem_length= (guint32) tvb_length_remaining(next_tvb, offset_payload);
                                            rem_length-=2;
                                            if (rem_length >= pl_val){
																rem_length-=2;
																proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, rem_length, "PDU data  : %d ", rem_length);
																offset_payload+=sdu_length;
																	} else {
                                                                                    proto_tree_add_text(BCnPDU_bom_tree, next_tvb, offset_payload, rem_length, "PDU data  : %d ", rem_length);
																					offset_payload+=rem_length;
																			}

                                            save_fragmented = pinfo->fragmented;
											pinfo->fragmented = TRUE;

											mte_frag_msg = fragment_add_seq_next(&mte_reassembly_table, next_tvb, offset_payload, pinfo, mte_seqid, NULL, rem_length, more_frags);

											pinfo->fragmented = save_fragmented;

											col_set_str(pinfo->cinfo, COL_INFO, " mte segment of a reassembled PDU ");

											pinfo->fragmented = save_fragmented;

                                        break;

			case 0x02: // End of Message

                                        sdu_length+=2;
                                        more_frags=FALSE;

                                        rem_length = (guint32) sdu_length;
                                        rem_length-=2;

                                        proto_tree_add_text(FT_connPDU_tree, next_tvb, offset_payload, rem_length , "PDU data : %d", rem_length);                                   offset_payload +=rem_length;
										disable_CRC=1;                             
										save_fragmented = pinfo->fragmented;                        
										pinfo->fragmented = TRUE;      
                                        mte_frag_msg = fragment_add_seq_next(&mte_reassembly_table,next_tvb, offset_payload, pinfo, mte_seqid, NULL, rem_length, more_frags);                               mte_frag_msg = fragment_get_reassembled_id(&mte_reassembly_table, pinfo, mte_seqid);

										//mte_tvb = tvb_new_chain(next_tvb, mte_frag_msg->tvb_data);
                                        mte_tvb = process_reassembled_data(next_tvb, offset_payload, pinfo, "mte Reassembled PDU", mte_frag_msg, &mte_frag_items, NULL, tree );

										if (mte_tvb) { /* Reassembled */
                                                try_tvb=mte_tvb;
												col_append_str(pinfo->cinfo, COL_INFO,"(Message reassembled) ");
												add_new_data_source(pinfo, try_tvb, "Reassembled mte");
                                                show_fragment_tree(mte_frag_msg, &mte_frag_items,tree, pinfo, try_tvb, &frag_tree_item);        
                                                    } else { /* Not last packet of reassembled message */

														col_append_str(pinfo->cinfo, COL_INFO,"(Message fragment) ");
                                                                }

                                                      pinfo->fragmented = save_fragmented;

										if (mte_tvb){
												SIG_PDU(mte_tvb, pinfo, tree);
														} else {
																	SIG_PDU(next_tvb, pinfo, tree);           
																	offset_payload+=sdu_length;
																	}
					
                                   break;