Packet capture: final version

[boba-buba]

Ticket 629 (http://www.helenos.org/ticket/629).

Final version of the utility pcapctl for packet capture inside HelenOS.

Detailed instructions and description are in the text of Bachelor thesis (https://dspace.cuni.cz/handle/20.500.11956/200578).

Usage

Utility: pcapctl - start/stop dumping (file format is .pcap)
Starting:
pcapctl -r data.pcap

Stopping:
pcapctl -t

Utility: pcapcat - list basic information about captured packets
pcapcat data.pcap

[jxsvoboda]

Before I continue the review, can you please fix your cstyle? Ccheck reports more than 500 issues. Most of it is your indentation is messed up. Probably fault of your text editor (configuration). Your indents are 4 spaces instead of 1 tab.

[boba-buba]

Sorry, forgot to run cchek before last push. Fixed

[jxsvoboda]

Thanks. Apart from what seems a couple of leftover debugging statements disabled with // it looks okay. I tried it out and it's quite nice. One major usability gap is that there is no way to see what captures are ongoing - with snoop/tcpdump you can see the utility running in the background, possibly displaying statistics. Here the capture is in the background - so you would need to be able to list out what captures are active. Also it would be great if you could dump the packets as they arrive - I imagine you could do that if the dump utility would be notified by the packet capturer when new packets arrive. I can imagine both as future improvements.

Currently GitHub cannot rebase this branch because of conflicts. Can you rebase it to latest master? I will then proceed with merging it.