Wireshark-dev: Re: [Wireshark-dev] Dissector global variable
From: Jaap Keuter <[email protected]>
Date: Mon, 30 Jun 2008 19:44:30 +0200

A global variable won't work for two reasons:
1. The capture file is accessed randomly.
2. You might have multiple exchanges you need to follow.

To tackle point 2 you can use conversations. Read about them in README.developer. To collect and keep track of protocol data across packets have a look at README.request_response_tracking.

Hans Glück wrote:
Hello, I´m writing a dissector and I want to implement "error recovery mode"/"flow control", therefor I need two gloabl variables where I can store some values (-> "next_expected_frame_to_be_recieved" and "next_expected_frame_to_be_send"). I declared them at the beginning of my c-file: static guint8 next_expected_frame_to_be_recieved = 0; static guint8 next_expected_frame_to_be_send = 0; And I set value of this variables in my dissector code: static void dissect_mux27010(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree){ ... if (received_successful()) { next_expected_frame_to_be_recieved++; } ... } My problem is: Every time I click in Wireshark at packet the value is increased e.g. click first packet -> next_expected_frame_to_be_recieved == 1 click second packet -> next_expected_frame_to_be_recieved == 2 click first packet -> next_expected_frame_to_be_recieved == 3 click second packet -> next_expected_frame_to_be_recieved == 4 But what I want is that the variables are increased step-by-step/ ordered (if packet n is an ACK -> increase; if packet n+1 is an ACK -> increase...) How can I realize this? Thanks for any advice. Chris