RE: HOWTO: pcap in 'background' thread

["Fulvio Risso" <risso () polito it>]

WinPcap has such a feature through the pcap_read_ex() call.
Everything can be done within a single thread.

We have the implementation for linux as well. Implementation in other
systems should be straightforward.
If the core members agree, we can commit these patches to the main libpcap
repository.

        fulvio

> -----Original Message-----
> From: owner-tcpdump-workers () sandelman ottawa on ca
> [mailto:owner-tcpdump-workers () sandelman ottawa on ca]On Behalf Of Steve
> Hyatt
> Sent: Monday, February 17, 2003 23:12
> To: tcpdump-workers () tcpdump org
> Subject: [tcpdump-workers] HOWTO: pcap in 'background' thread
>
>
> Hi all.
>
> I am maintaining a piece of software which uses the pcap library
> to monitor packets being sent from a given machine and then
> categorizing this packets based on the destination IP grabbed
> from the packet's headers.  The software uses pthreads to
> separate the recording of the packets (through call to
> pcap_open_live, pcap_loop, and a callback funtion) in one thread
> from the processing of this data in another pthread thread.  The
> implemented use of pthreads and mutex's are giving me problems
> which I would like to resolve by removing pthreads.
>
> I am not sure however how this can be done.  What i'd like to be
> able to do is something like the following pseudo-code:
>
>   while (!done) {
>     use pcap to count packets and bytes for next 200 ms;
>     evaluate last 200ms worth of data and process;
>   }
>
> The idea is only have one thread which does both things.  This
> only would work however if there is a way to ask the pcap library
> to 'watch packets for X MS'.  How can I do this?
>
> I think I can do this by using fork to have a child process do
> the capturing and using the callback to 'pipe' the data back to
> the parent process, and have the wile loop in the parent process.
>  However one of the platforms that I need a solution for does not
> have the fork method (its an MMU-less platform).
>
> Any help would be greatly appreciated.
>
> Steve
> shyatt () bigbangwidth com
>
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