interactive service v3

interactive service v3

v1: Heiko Hund
 - Message-ID: <2215306.x9ci9DhAZ9@de-gn-40970>
 - extend openvpn service to provide "automatic service" and "interactive
   service" (which is used by GUI and OpenVPN to run openvpn non-privileged
   and still be able to install routes and configure IPv6 addresses)
 - add --msg-channel <n> option to openvpn to tell it which pipe to use
   to talk to the interactive service (used in tun.c for ifconfig + ARP
   flush, and route.c for routing)
 - add openvpn-msg.h with message definitions for talking to interactive
   service
 - routing in openvpn uses message-pipe automatically if --msg-channel <n>
   is configured, no other option needed
 - today, the integration in route.c and tun.c is windows-only, but could
   be adapted to other platforms

v2: Steffan Karger
 - Message-ID: <548D9046.5000600@karger.me>
 - include "openvpn-msg.h" not "include/openvpn-msg.h"
 - add $(top_srcdir)/include to openvpnsrv build for out-of-tree builds

v3: Gert Doering, rebasing and integrating review feedback
 - rebased to 417fe4a72c
 - r->metric_defined is now r->flags & RT_METRIC_DEFINED (c3ef2d2333fb)
 - move "openvpn-msg.h" include inside #ifdef WIN32 (windows-only right now)
 - hide "msg_channel" extra option inside tt->tuntap_options, so we do not
   need an extra argument to all the add/del_route...() functions
 - do_route_ipv6_service(): use r->adapter index (if set) for RGI6 routes

Signed-off-by: Heiko Hund <heiko.hund@sophos.com>
Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Selva Nair <selva.nair@gmail.com>        (Service changes)
Acked-by: Arne Schwabe <arne@rfc2549.org>          (OpenVPN changes)
Message-Id: <1453835508-26119-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/11027
Signed-off-by: Gert Doering <gert@greenie.muc.de>