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If I have the number of a frame, is it possible to then look up the actual frame/packet?

I'm trying to make some enhancements to io_stat.c, and I'd like to show some information about the packet inside the graph window itself, when clicked on. The only context I have in that situation is the frame number.

asked 02 Jul '11, 01:10

Jackson%20Zhou's gravatar image

Jackson Zhou
accept rate: 0%

retagged 02 Jul '11, 02:00

helloworld's gravatar image


In 1.6 and later:

frame_data *fd;
fd = frame_data_sequence_find(cfile.frames, frame_number);

will get you the frame_data structure for the frame with the specified frame number. Whether that gives you all the information you need is another matter (and the frame_data structure will probably get things removed from it over time, to save memory - there's one of them for every packet in a capture).

The packet_info structure is another matter. That is generated when the packet is dissected, and is not saved (saving it would make Wireshark's memory usage even worse).

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answered 02 Jul '11, 11:40

Guy%20Harris's gravatar image

Guy Harris ♦♦
accept rate: 19%

edited 02 Jul '11, 11:41

Thanks, That answer was really helpful.

How would I get the packet info, even in the most extreme case? Would I use cum_bytes and file_off to get the raw data and redissect it? I mean, the main wireshark window is able to offer packet info on any arbitrary row so that information must either be stored somewhere or recalculated right?

(02 Jul '11, 12:55) Jackson Zhou

Yes, you'd have to get the raw data and redissect it. See, for example, cf_read_frame_r() in file.c, to read a packet from a capture given the frame_data structure, and new_packet_window() in gtk/packet_win.c, which, given a pseudo-header and pile of raw packet data (which you'd have read with cf_read_frame_r()), dissects the packet with epan_ calls and pops up a window with the packet details and hex dump.

(02 Jul '11, 13:07) Guy Harris ♦♦

Mission accomplished. Thank you.

(04 Jul '11, 02:08) Jackson Zhou
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question asked: 02 Jul '11, 01:10

question was seen: 9,226 times

last updated: 04 Jul '11, 02:08

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