1. pcap_get_selectable_fd() may return -1 for some devices, even if the
platform as a whole supports select() on these handles. Check for
this condition throughout.
2. The various backend system calls (kevent, poll, epoll, etc.) do not
sleep for the timeout period if no valid handles are registered,
unlike select on UNIX. This leads to busy wait, looping continuously.
Instead, we call usleep() in those cases.
For platforms without selectable pcap handles (e.g. Windows), the
arrival of data for a pcap read would previously skip checking for any
triggered non-pcap events in that loop iteration. This is not usually a
problem because the next loop will be triggered immediately, picking up
the non-pcap events before any further pcap data arrives. However,
excessive pcap data on a handle in immediate mode might prevent the
engine loop from checking for non-pcap events for long enough to result
in timeouts. Instead, do a non-blocking check for triggered events in
this case and handle those in the same loop iteration.
Make current loglevel and current log callback global
to the library. Attaching them to the nsock pool doesn't
bring any benefit and prevents from logging activity in
code sections that don't have access to a pool (such as
proxy chain specification parsing).
Updated external calls and nsock tests accordingly.
This prevents nsock from iterating over the whole list of events at
each runloop, thus improving performance.
It made it necessary to have pointers from the msevents to the event
lists they belong to. The patch therefore also changes gh_list from
autonomous containers to embedded structures.
Added unit tests accordingly and cosmetic changes to make things look
more consistent.
Reworked the logging infrastructure to make it more flexible
and consistent.
Updated nmap, nping and ncat accordingly. Nsock log level can
now be adjusted at runtime by pressing d/D in nmap.
