On Feb 6, 2014, at 8:13 AM, Michal Sekletar <msekl...@redhat.com> wrote:
> Activated refers to pcap_t handle. Before you can do capture on the device
> you have to have handle and after that capture parameters are set and finally
> handle is marked as activated. So it doesn't refer to status of the device in
> OS.
Yes.
With pcap_open_live(), there is a fixed set of parameters that can be specified
- promiscuous mode, snapshot length, and buffering timeout.
Paolo Abeni added support for the memory-mapped capture mode, and wanted the
ability to configure the ring buffer size from the program. I wanted one to
configure the capture buffer size for other platforms as well; there was
already one in WinPcap for Windows, but that was a call you make after
pcap_open_live(), and that wouldn't work for BPF on *BSD/OS X.
I also wanted the ability to add new parameters in the future, rather than just
having a pcap_open_live_with_buffer_size() call that just added the buffer
size, with a new open call having to be added for each new parameter.
After some discussion on tcpdump-workers, we came up with a scheme where:
you create a handle for a device with pcap_create();
you make calls to routines to set various parameters, handing them that
handle;
when you've set all the parameters, you call pcap_activate() to
"activate" the handle, opening the device with the specified parameters.
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