dnsdist: Add a 'source' option to select the source addr/interface
It only supports one source address/interface per downstream server.
The more I tried to support more than one, the more I realized I was
in fact having grouping several DS into one, without the benefits
of separate stats and status checking. In particular, having several
sources adresses mean that we would get "random" failures if some
addresses are allowed on the backend and some others are not.
Simply adding the same backend several times with different source
addresses means that only the ones with faulty addresses will be
disabled.
Closes #3138.
projects / pdns / commit