http://seclists.org/nmap-dev/2012/q3/56. r29134 already addressed the issue but
was incomplete.
This replaces r29134 with an engine-agnostic approach, and additionally enforces
the reset of IOD flags before use or re-use.
The Nsock select engine stores readiness information in a mask instead
of doing an FD_ISSET against the descriptor every time. This is a good
idea, but it removed a special case in the pre-engines code: in case
PCAP_CAN_DO_SELECT is not defined, we can't do FD_ISSET on the
descriptor because it is -1. Here we check for that occurrence and set
EV_READ in the mask so that a non-blocking pcap read can happen every
iteration.
support for system-specific scalable IO notification facilities without breaking
portability. This initial version comes with an epoll(7)-based engine for Linux
and a select(2)-based fallback engine for all other operating systems.
This required an important refactoring of the library but the external API was
preserved.
The rewrite also tries to bring the coding standards of nmap to nsock.
See http://labs.unix-junkies.org/nsock_engines.html for the details.
