Wireshark · Wireshark-dev: Re: [Wireshark-dev] Reassembling Packets need some help plz

[Marcel Haas <inf462@xxxxxxxxxxx>]

Nobody an idea ?


On Tue, 20 Sep 2011 14:43:04 +0200, Marcel Haas <inf462@xxxxxxxxxxx> 
wrote:
> Hello,
>
> im just writeing my first dissector and i have some problems with the
> reassembling
> My prtocoll contain some fields for Snode =ID ,Packetnumber and total 
> packets
> i get them with
> snode =tvb_get_guint8(tvb,offset);offset +=1;
> pnum =tvb_get_guint8(tvb,offset);offset +=1;
> totalp =tvb_get_guint8(tvb,offset);
>
> Example for a packet split into 3 :
>
> Snode=12
> pnum=1
> total=3
>
> Sonde=12
> pnum=2
> total=3
>
> Snode=12
> pnum=3
> total=3
>
> the packet consists of an Trans Header, a App Header and Data.
> IF its fragmented only the frist packet consists auf tran,app and 
> data
> the other fragments consists only of trans and data.
> For the reassembled tvb only the data are importent. the lengh of the
> trans-header r given in a field loh.
> I think my fragment_add_seq_check function doesnt work right cause
> everytime i get a 0 returned
> thx.
>
> Code:
>       save_fragmented = pinfo->fragmented;
>
>         if (totalp > 1 && pnum<=totalp){    //check if it has to be
> reassembled
>             if(pnum==1){
>                 offset2=loh+20;            // First packet, Packet
> with Tran + App Header ,App Header =20 Byte
>             }
>             else{
>                 offset2=loh;              // Not First Packet only
> trans header
>             }
>            if(totalp==pnum){ more_frag=FALSE;}    //Total Packet ==
> pnum =>Last Packet set more_frags =FALSE
>            else {more_frag=TRUE;}               // Not Last Packet
> =>set more_frags=TRUE
>
>             msg_seqid =snode;
>             msg_num = pnum-1;
>             pinfo->fragmented = TRUE;
>             frag_msg = fragment_add_seq_check(tvb, offset2, pinfo,
>                 msg_seqid, // ID for fragments belonging together
>                 msg_fragment_table, // list of message fragments
>                 msg_reassembled_table, // list of reassembled 
> messages
>                 msg_num, // fragment sequence number
>                 tvb_length_remaining(tvb, offset2), //fragment length
> - to the end
>                 more_frag); // More Frag
>
>                 printf("%d",(int)frag_msg);// PRINTF wieder raus
>             new_tvb = process_reassembled_data(tvb, offset2, pinfo,
>                 "Reassembled Message", frag_msg, &msg_frag_items,
>                 NULL,nos_tree);
>
>             if (frag_msg) { // Reassembled
>                 col_append_str(pinfo->cinfo, COL_INFO,
>                         " (Message Reassembled)");
>             } else { // Not last packet of reassembled Short Message
>                 col_append_fstr(pinfo->cinfo, COL_INFO,
>                         " (Message fragment %u)", msg_num);
>                 col_append_fstr(pinfo->cinfo, COL_INFO,
>                          " (Frag:  %u)", pinfo->fragmented);
>                 col_append_fstr(pinfo->cinfo, COL_INFO,
>                           " (Visit:  %u)", pinfo->fd->flags.visited);
>                 col_append_fstr(pinfo->cinfo, COL_INFO,
>                           " (Fragmsg:  %d)", (int)frag_msg);
>
>             }
>
>             if (new_tvb) { // take it all
>                 col_append_str(pinfo->cinfo, COL_INFO,
>                         "(NEW TVB)");
>                 //offset=0;
>                 //proto_tree_add_item(nos_tree, hf_nos_data, new_tvb,
> offset, -1, FALSE);
>                  next_tvb = new_tvb;
>             } else { // make a new subset
>                 next_tvb = tvb_new_subset(tvb, offset2, -1, -1);
>             }
>
>         }
>
>         else { // Not fragmented
>             next_tvb = tvb_new_subset(tvb, offset2, -1, -1);
>         }
>
>         pinfo->fragmented = save_fragmented;
>
>
>
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