Re: Reassemble packets decoding - not proper

[Guy Harris <guy () alum mit edu>]

On Dec 6, 2009, at 10:44 PM, Rach, Darshan wrote:

> Kindly let me know what might have gone wrong.

Sorry, I forgot to indicate that, once you get to the point where you  
dissect the field with the "request satisfied" bit, you're dealing  
with a tvbuff that starts with that field, so you have to reset  
packet_field_offset to 0, *AND* you have to fetch fields using  
next_tvb, not tvb, so you're using that tvbuff:

                                if (next_tvb == NULL)
                                {
                                        /* Just a fragment - put an item into the protocol tree for the  
fragment data */
                                        proto_tree_add_text(oqtp_tree, tvb, packet_field_offset, -1,  
"Fragment data");
                                }
                                else
                                {
                                        /* Not a fragment, or fragments were reassembled */
                                        packet_field_offset = 0;

                                        /*Request Satisfied*/
                                        request_satisfied = tvb_get_guint8(next_tvb, packet_field_offset);
                                        proto_tree_add_uint(oqtp_tree, hf_request_satisfied, next_tvb,  
packet_field_offset, 1, ((request_satisfied & 0x80) >> 7));

                                        /*Reserved_for_future_use*/
                                        reserved_for_future_use = ((tvb_get_guint8(next_tvb,  
packet_field_offset)& 0x7E) >> 1);
                                        proto_tree_add_uint(oqtp_tree, hf_reserved_for_future_use,  
next_tvb, packet_field_offset, 1, reserved_for_future_use );

                                        /*No Extended pd syntax*/
                                        no_extended_pd_syntax = (tvb_get_guint8(next_tvb,  
packet_field_offset) & 0x1);
                                        proto_tree_add_uint(oqtp_tree, hf_no_extended_pd_syntax,  
next_tvb, packet_field_offset, 1, no_extended_pd_syntax );
                                        packet_field_offset += 1;

                                        /*Number of classifications*/
                                        proto_tree_add_item(oqtp_tree, hf_num_classifications, next_tvb,  
packet_field_offset, 1, FALSE);
                                        num_classifications = tvb_get_guint8(next_tvb,  
packet_field_offset);
                                        packet_field_offset += 1;

                                                ...
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