[ULOGD2] UNIXSOCK plugin (v5)

[Pierre Chifflier <chifflier@edenwall.com>]

Hi,

Here is an updated version of the UNIXSOCK plugin.

Changes for v5:
- align all structures on 64 bits instead of 32
  This has been tested on a sparc64 (thanks to Jan)
- update pcap2ulog to handle different pcap formats

Changes for v4:
- use structures instead of reading integers directly
- all structures and fields are now aligned (4 bytes)
- update pcap2ulog script to use aligned data as well

Changes for v3:
- if the bufsize value (from conf) is 0, try to guess the buffer size
  using getsockopt(SOL_SOCKET, SO_RCVBUF ..)
- set default path to /var/run/ulogd/ulogd2.sock with mode 0600
- add new configuration options perms, owner and group to be able
  to set these parameters on the created socket
- change the input algorithm to make it more robust against junk data (which
  can happen if the client is desynchronized)
- fixed a few bugs

Description:

[1] add new input plugin UNISOCK, using a unix socket. This allows userspace
applications to send packets to ulogd, for example to send packets offline.
It uses a key-length-value protocol to handle optional fields or extensions.

[2] is a Perl script to load a PCAP file and send it to ulogd using the
UNIXSOCK plugin.

Pierre