Wireshark · Ethereal-dev: Re: [Ethereal-dev] desegment TCP streams with unknown size

[Peter Johansson <Peter.xc.Johansson@xxxxxxxxxxxx>]

Dickson Law wrote:

> Hi there 
> I have a need to reassembly muitlple PDUs into something usable for 
> dissection.  The trouble is the target protocol does not compute the 
> lenght of the message sent, but only a terminating byte 0x03 is used.  
> I presume I would not be able to using the tcp_dissect_pdus functions 
> as per README.developer but I am having problem understanding the 
> alternative method described.
>
> The code fragment I am trying to use:
>
>       int offset=0;
> /* Looking for 0x03*/
>
>        len = tvb_find_guint8(tvb, offset, -1, 0x03);
>        fprintf(stderr,"0x03 found at %d\n",len);
>                    if ( len = -1 ) {
>               /* get 1 more byte*/
>                pinfo->desegment_offset = offset;
>                pinfo->desegment_len = 1;
>                return;
>        }
>
>
> what this gets me is it completely scrambled my dissectors, which has 
> been working fine up till then.
>
>
> Can anyone help?
>
> thanks
>
> dickson

If this really is the code you tried (and its not just a copy and paste 
typo) I guess the line "if( len = -1)" will get you into trouble as it 
always assigns -1 to len and constantly asks for additional data.

/ Peter