Wireshark · Wireshark-dev: Re: [Wireshark-dev] tcp_dissect_pdus. get reassemble TCP

[Siyang Xiong <siyangxiong2010@xxxxxxxxx>]

Hi,

I read the 2.7, and in my case i should use the 2nd method for unpredictable length, However I still meet prblms:

in the code: (I add the bold comment)

static void dissect_cstr(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)

  {

     guint offset = 0;

     while(offset < tvb_reported_length(tvb)) {

         gint available = tvb_reported_length_remaining(tvb, offset);

         gint len = tvb_strnlen(tvb, offset, available); // I always get -1 here

 

         if( -1 == len ) {

             /* we ran out of data: ask for more */

             pinfo->desegment_offset = offset;

             pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;

             return;

         }

 

         col_set_str(pinfo->cinfo, COL_INFO, "C String");

 

         len += 1; /* Add one for the '\0' */

 

         if (tree) {

             proto_tree_add_item(tree, hf_cstring, tvb, offset, len,

                                 ENC_ASCII|ENC_NA);

         }

         offset += (guint)len;

     }

     //I never reach here, cannot get the data.

     /* if we get here, then the end of the tvb coincided with the end of a

        string. Happy days. */

  }