Re: Someone please help me on this Reassemly fragmentation

[Raj sekar <mrajsekar () gmail com>]

Hi pascal

Thanks for your time.

just to verify few things

1. Offset_payload  is guint8  is that ok?

2.  pdu_length -> is the total length of the pdu  (total length = 22 ;
beginning of message 20 and end of message 2 bytes)

I have also tried replacing pdu_length, with rem_length  (which is only
particular length example end of message 2 bytes)

3. Do I need to use table destroy function ? In the end ?

4. Do I need to use fragment_set_total_length? I have tried already. But no
change so I have commented off

5. I have not used any GHASH table in my code. Some people used that and
use of fragment table ang reassembly table.

fragment_add_check(
                       &mns_reassembly_table,
                           next_tvb,
                          offset_payload,
                        pinfo,
mns_seqid,
                        NULL,
                          msg_seqid,

                      pdu_length,
      (stype == 0x02) ? FALSE : TRUE)  );

Thanks again  and have a nice day!

Raj
 On 25 Feb 2015 19:33, "Pascal Quantin" <pascal.quantin () gmail com> wrote:

> Back to the mailing list
>
> 2015-02-25 12:07 GMT+01:00 Raj sekar <mrajsekar () gmail com>:
>
> > Hi Pascal ,
> >
> > I have modified as per your instruction . Still iam getting Fragment not
> > successful and reassembly unsuccessful. :(
> >
> > You can see my code. It exactly as you said.
> >
> > Please help.
>
> Then it's really time for you to take a debugger and step in your code so
> as to verify what's wrong with your code. After all you are the only one
> having the capture and the code running, so confirm that the parameters
> given to fragment_add_seq_check() are the expected ones.
>
> > Raj
> >
> >
> >
> >
> > On Wed, Feb 25, 2015 at 5:36 PM, Pascal Quantin <pascal.quantin () gmail com
> > > wrote:
> >
> > > Le 25 févr. 2015 10:07, "Raj sekar" <mrajsekar () gmail com> a écrit :
> > >
> > > > i have a off-line capture file..
> > > >
> > > > iam developing dissector for customised protocol
> > > >
> > > > i have a old ethereal tool for the same protocol now iam developing in
> > > wireshark.
> > > > My message pdu got 3 different message types
> > > >
> > > >   1. Beginning of message
> > > >   2. continuation of message
> > > >   3. end of message
> > > >
> > > > in one Frame at a time it can receive any one of this message
> > > >
> > > > when it End of message sequence comes i need to reassemble whole PDU
> > > >
> > > > i have opened in ethereal tool and my output are like this
> > > >
> > > > Frame Number
> > > > Message type
> > > > pollflag
> > > > NS (sequence Number)
> > > > NR (SEquence ID)
> > > >
> > > >
> > > > 283
> > > > Beginning of message
> > > > 0
> > > > 0
> > > > 0
> > > > 343
> > > > End of message
> > > > 0
> > > > 1
> > > > 0
> > > >  -> Reassembly done here
> > > >
> > > >
> > > > 379
> > > > Beginning of message
> > > > 0
> > > > 2
> > > > 1
> > > > 414
> > > > Continuation of message
> > > > 0
> > > > 3
> > > > 1
> > > > 416
> > > > Continuation of message
> > > > 0
> > > > 4
> > > > 1
> > > > 417
> > > > End of Message
> > > > 1
> > > > 5
> > > > 1
> > > >  -> Reassembly done here
> > > >
> > > >
> > > > 536
> > > > Beginning of message
> > > > 0
> > > > 6
> > > > 2
> > > > 541
> > > > End of meassage
> > > > 0
> > > > 7
> > > > 2
> > > >  -> Reassembly done here
> > >
> > > Hi,
> > >
> > > I'm really happy to see that you did not follow the explanations and
> > > advices I gave you yesterday by private email because you contacted me
> > > directly instead of sending to the mailing list.
> > > As I told you your code cannot work as-is because it assumes that you
> > > will always get a begin - continuation - end sequence (so 3 fragments). If
> > > this is not the case and if you are sure to always receive the fragments in
> > > order, you could use an (evil ;)) global variable to keep track of the
> > > current fragment number. See a suggestion below in your code. If you put
> > > some effort in understanding what I explained you, and ensure that you are
> > > correctly setting the parameters of the reassembly API, it should work
> > > correctly.
> > >
> > >
> > > > I have used my code structure like this
> > > >
> > > >
> > > > guint32 rem_length;
> > > > guint8 iflag,pf,stype,flag_sel,num_sel,i,sflag;  //
> > > > guint32 pdu_len;
> > > > guint8 save_fragmented;
> > > > gboolean more_frags = FALSE;
> > > > gboolean need_frag = FALSE;
> > > > const *data = NULL;
> > > > //tvbuff_t *try_tvb = NULL;
> > > > //proto_item *frag_tree_item;
> > > > tvbuff_t  *rass_tvb = NULL;
> > > > tvbuff_t  *mns_tvb = NULL;
> > > > guint32 msg_seqid;
> > >
> > > replace it by:
> > >
> > > static guint32 msg_seqid = 0;
> > >
> > > > guint32 mns_seqid = 0;
> > > > guint32 mns_seqnum = 0;
> > > > fragment_head *frag_msg = NULL;
> > > > gboolean reassembled = FALSE;
> > > > //guint32  reassembled_in = 0;
> > > > tvbuff_t * res_tvb = NULL;
> > > > fragment_head * frag_head = NULL;
> > > > proto_tree *ptree = NULL;
> > > > ptree = proto_tree_get_parent(tree);
> > > >
> > > >
> > > >          pf = (tvb_get_guint8(next_tvb, offset_payload) & 0x40) >>6 ;
> > > // Bit 7 pf
> > > >          mns_seqnum = (tvb_get_ntohs(next_tvb, offset_payload) &
> > > 0x3ff00000) >>20; // 10 Bits are ns
> > > >          offset_payload +=1;
> > > >          mns_seqid = (tvb_get_ntohs(next_tvb, offset_payload) &
> > > 0x0ffc0000) >>18; // 10 bits are nr
> > > >          offset_payload +=1;
> > > >          stype = (tvb_get_guint8(next_tvb, offset_payload) & 0x03) ;
> > > // 2 bits LSB are Stype
> > > >          offset_payload -=2;
> > > >
> > > >          FT_BCnPDU_item = proto_tree_add_text(tree, next_tvb,
> > > offset_payload, bctsdu_length, "BCnPDU (Formatted) : Information, I flag =
> > > 0x%02x, Pf = 0x%02x, Ns = 0x%02x, Nr = 0x%02x ",
> > > iflag,pf,mns_seqnum,mns_seqid );
> > > >          FT_BCnPDU_tree = proto_item_add_subtree(FT_BCnPDU_item,
> > > ett_FT_BCnPDU);
> > > >          proto_tree_add_text(FT_BCnPDU_tree, next_tvb, offset_payload,
> > > 1, " bctsdu_length: %d", bctsdu_length);
> > > >          proto_tree_add_text(FT_BCnPDU_tree, next_tvb, offset_payload,
> > > 1, "I flag : 0x%02x (%s)", iflag,val_to_str(iflag,true_false_vals,"%s"));
> > > >          proto_tree_add_text(FT_BCnPDU_tree, next_tvb, offset_payload,
> > > 1, "Pf : 0x%02x (%d)", pf,pf);
> > > >          proto_tree_add_text(FT_BCnPDU_tree, next_tvb, offset_payload,
> > > 2, "Ns : 0x%02x (%d)", mns_seqnum,mns_seqnum);
> > > >          offset_payload +=1;
> > > >          bctsdu_length-=1;
> > > >          proto_tree_add_text(FT_BCnPDU_tree, next_tvb, offset_payload,
> > > 2, "Nr : 0x%02x (%d)", mns_seqid,mns_seqid);
> > > >          offset_payload +=1;
> > > >          bctsdu_length-=1;
> > > >          proto_tree_add_text(FT_BCnPDU_tree, next_tvb, offset_payload,
> > > 1, "BCnSegType : 0x%02x (%s)",
> > > stype,val_to_str(stype,BCn_Seg_Type_vals,"%s"));
> > > >          offset_payload +=1;
> > > >          bctsdu_length-=1;
> > > >
> > > >
> > > >          switch (stype){
> > > >
> > > >          case 0x00: // Continuation of Message
> > > >
> > > >            msg_seqid=1;
> > >
> > > replace it by:
> > >
> > > msg_seqid++;
> > >
> > > >            bctsdu_length+=1;
> > > >
> > > >            rem_length = bctsdu_length;
> > > >            proto_tree_add_text(FT_BCnPDU_tree, next_tvb,
> > > offset_payload, rem_length , "PDU data : %d", rem_length);
> > > >          break;
> > > >
> > > >          case 0x01: // Beginning of Message
> > > >
> > > >             msg_seqid=0;
> > > >
> > > >
> > > >             BCnPDU_stype_item = proto_tree_add_text(FT_BCnPDU_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, "MACSAPFLAGS");
> > > >             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);
> > > >             pdu_len = (tvb_get_ntohl(next_tvb, offset_payload) &
> > > 0x07ff0000) >>16; // PDU Length - 11 Bits
> > > >             proto_tree_add_text(BCnPDU_bom_tree, next_tvb,
> > > offset_payload, 2, "PDU Length : 0x%02x (%d)", pdu_len,pdu_len);
> > > >             offset_payload+=2;
> > > >             bctsdu_length-=2;
> > > >
> > > >
> > > >             if (rem_length >= pdu_len){
> > > >
> > > >             rem_length-=2;
> > > >
> > > >             proto_tree_add_text(BCnPDU_bom_tree, next_tvb,
> > > offset_payload, rem_length, "PDU data (if) : %d ", rem_length);
> > > >             } else {
> > > >
> > > >             proto_tree_add_text(BCnPDU_bom_tree, next_tvb,
> > > offset_payload, rem_length, "PDU data (else) : %d ", rem_length);
> > > >             }
> > > >
> > > >
> > > >          break;
> > > >
> > > >          case 0x02: // End of Message
> > > >
> > > >            msg_seqid=2;
> > >
> > > replace it by:
> > >
> > > msg_seqid++;
> > >
> > > >            bctsdu_length+=2;
> > > >
> > > >            more_frags=TRUE;
> > > >
> > > >
> > > >            rem_length =  bctsdu_length;
> > > >            rem_length-=2;
> > > >
> > > >            proto_tree_add_text(FT_BCnPDU_tree, next_tvb,
> > > offset_payload, rem_length , "PDU data : %d", rem_length);
> > > >            disable_CRC=1;
> > > >
> > > >
> > > >          break;
> > > >
> > > >          case 0x03: // Single Segment Message
> > > >             // No need of fragmentation and reassembly
> > > >             offset_payload+=1;
> > > >             bctsdu_length-=1;
> > > >             if (bctsdu_length>0){
> > > >
> > > >              ALSIGPDU(next_tvb, pinfo, tree);
> > > >                }
> > > >
> > > >
> > > >            break;
> > > >
> > > >            }
> > > >
> > > >             if ( stype==0x01 || stype==0x02 || stype==0x00  ){
> > > >
> > > >
> > > >                        pinfo->fragmented = TRUE;
> > > >                        save_fragmented = pinfo->fragmented;
> > > >
> > > >                        frag_head =
> > > fragment_add_check(&mns_reassembly_table,
> > > >                           next_tvb,
> > > >                           offset_payload,
> > > >                           pinfo,
> > > >                           msg_seqid,
> > >
> > > this should be mns_seqid
> > >
> > > >                           NULL,
> > > >                           mns_seqid,
> > >
> > > this should be msg_seqid
> > >
> > > >                           pdu_length,
> > > >                           ((msg_seqid == 2)?0:1));
> > >
> > > this should be:
> > >
> > > (stype == 0x02) ? FALSE : TRUE)
> > >
> > > >                         if (frag_head != NULL) {
> > > >
> > > >                            col_append_str(pinfo->cinfo, COL_INFO, "
> > > [Fragment Successful]");
> > > >                           } else {
> > > >
> > > >                           col_append_str(pinfo->cinfo, COL_INFO, "
> > > [Fragment Not Successful]");
> > > >                           }
> > > >
> > > >                           save_fragmented = pinfo->fragmented;
> > > >                        pinfo->fragmented = FALSE;
> > > >
> > > >
> > > >
> > > >                        res_tvb = process_reassembled_data( next_tvb,
> > > offset_payload, pinfo, "Reassembled PDU", frag_head, &mns_frag_items, NULL,
> > > FT_BCnPDU_tree );
> > > >                        save_fragmented = pinfo->fragmented;
> > > >                        pinfo->fragmented = FALSE;
> > > >
> > > >                        if (res_tvb) {
> > > >
> > > >                           col_append_str(pinfo->cinfo, COL_INFO, "
> > > [mns reassembled]");
> > > >                           } else {
> > > >                             col_append_str(pinfo->cinfo, COL_INFO,
> > > "[mns not reassembled ]");
> > > >                             }
> > > >                          offset_payload+=rem_length;
> > > >                          bctsdu_length-=rem_length;
> > > >
> > > >                    }
> > > >
> > > >
> > > >
> > > >     I dont have any clue my fragmentation always not succesful. please
> > > help.
> > > > Thanks
> > > >
> > > > Best Regards
> > > > Raj
> > > ___________________________________________________________________________
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> > >
> > >
> > >
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