Wireshark-dev: Re: [Wireshark-dev] Protocol Col / Info col error
From: vinayak kamath <[email protected]>
Date: Tue, 31 Mar 2009 10:45:10 -0700
Hi Steve,
Heres more of dissectors code
THis code works fine for wireshark 0.99.5 on kinux or wireshark 1.0.0 on windows.
But wirehark 1.0.6 doesn't display protocol/info item.  ABC is protocol name...
##################################################################################
include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>

#include <gmodule.h>
#include <epan/prefs.h>
#include <epan/packet.h>
#include <epan/dissectors/packet-tcp.h>

/* forward reference */
void proto_register_abc();
void proto_reg_handoff_abc();

/* Define version if we are not building Wireshark statically */

#ifndef ENABLE_STATIC
G_MODULE_EXPORT const gchar version[] = "0.0";
#endif

/* globals for this file */
static int proto_abc = -1;
static const guint8  ABCDECODE_ABC_HEADER_LENGTH =18;

#ifndef ENABLE_STATIC
G_MODULE_EXPORT void plugin_register(void)
{
   /* register the new protocol, protocol fields, and subtrees */
   if (proto_abc == -1) { /* execute protocol initialization only once */
      proto_register_abc();
   }
}

G_MODULE_EXPORT void plugin_reg_handoff(void){
   proto_reg_handoff_abc();
}
#endif


static  int ett_abc = -1;
  /* Setup protocol subtree array */
static int *ett[] = {&ett_abc };


guint32 dissect_abc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  guchar  *msgName;
  guint32 numBits=0, msgId;
  const guint8 versionField =13;

  guint iDataLen; /* length of packet */


   /* Clear out stuff in the info column */
  if (check_col(pinfo->cinfo,COL_INFO))
  {
    col_clear(pinfo->cinfo,COL_INFO);
  }

  iDataLen = tvb_length(tvb); /* get length of packet */

  if ( IsABCMessage(tvb, iDataLen)) /* check if it is a ABC  message */
{
 if (check_col(pinfo->cinfo,COL_PROTOCOL))  // #######This is NULL, asa a result it doesn't enter the if condition
    {
      col_set_str(pinfo->cinfo,COL_PROTOCOL, "ABC");
    }

    msgId = GetMessageId(tvb);
    msgName = (guchar *)match_strval(msgId, abcMessageType_value_string_table);

    if(msgName) /* valid abc message */
    {
      if (check_col(pinfo->cinfo, COL_INFO)) // #######This is NULL, asa a result it doesn't enter the if condition
      {
        col_add_fstr(pinfo->cinfo, COL_INFO,"ABC: %s", msgName);
      }
      if (tree)
      { /* we are being asked for details */
        proto_item *ti;
       abcMessage abcMsg;

        abcMsg.msgId = msgId;
        abcMsg.version = tvb_get_guint8(tvb, versionField);

        ti = proto_tree_add_item(tree, proto_abc, tvb, 0, -1, FALSE);


        tree = proto_item_add_subtree(ti, ett_abc);

        numBits = abcMessage_dissect(&abcMsg,proto_abc, tvb, 0, pinfo, tree);
      }
    }

     else  // not a valid msg id
    {
      if (check_col(pinfo->cinfo, COL_INFO))
      {
        col_add_fstr(pinfo->cinfo, COL_INFO, "ABC: Invalid Message Id (%u)", msgId);
      }
    }
  }
  else //Not an ABC message
  {
    if (check_col(pinfo->cinfo, COL_INFO))
    {
      col_set_str(pinfo->cinfo, COL_INFO, "ABC: Not a ABC message");
    }
  }
  return numBits; /*in case of err, 0 is returned */
}
##################################################################################   




thanks
vinayak






On Mon, Mar 30, 2009 at 8:58 PM, Stephen Fisher <[email protected]> wrote:
On Mon, Mar 30, 2009 at 05:44:26PM -0700, vinayak kamath wrote:

> I am using wireshark 1.0.6 on RHEL 4 linux. ( Built from source
> code)... I have added by own dissector . I am able to decode the
> messages correctly. But the Protocol & Info column on GUI doesn't show
> the right value.
>
> Is this a known thing ???

No.

> Heres a code snippet for the dissector

> In both these cases it never enters the if condition as a result of
> which the protocol/Info item never gets set to the required value.

Would you mind sending more or all of the dissector's code if it is not
too big?


Steve

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