It is sometimes needed in application server environments to easily tell
if a source is local to the machine or a remote one, without necessarily
knowing all the local addresses (dhcp, vrrp, etc). Similarly in transparent
proxy configurations it is sometimes desired to tell the difference between
local and remote destination addresses.
This patch adds two new sample fetch functions for this :
dst_is_local : boolean
Returns true if the destination address of the incoming connection is local
to the system, or false if the address doesn't exist on the system, meaning
that it was intercepted in transparent mode. It can be useful to apply
certain rules by default to forwarded traffic and other rules to the traffic
targetting the real address of the machine. For example the stats page could
be delivered only on this address, or SSH access could be locally redirected.
Please note that the check involves a few system calls, so it's better to do
it only once per connection.
src_is_local : boolean
Returns true if the source address of the incoming connection is local to the
system, or false if the address doesn't exist on the system, meaning that it
comes from a remote machine. Note that UNIX addresses are considered local.
It can be useful to apply certain access restrictions based on where the
client comes from (eg: require auth or https for remote machines). Please
note that the check involves a few system calls, so it's better to do it only
once per connection.
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