Gateway devices operating as an HA pair w/VRRP or CARP may send UPnP
replies from static addresses rather than the floating gateway address.
This commit relaxes our source address verification such that we parse
responses from non-gateway IPs, and re-point the UPnP root desc
URL to the gateway IP. This ensures we are still interfacing with the
gateway device (assuming L2 security intact), even though we got a
root desc from a non-gateway address.
This relaxed handling is required for ANY port mapping to work on certain
OPNsense/pfsense distributions using CARP at the time of writing, as
miniupnpd may only listen on the static, non-gateway interface address
for PCP and PMP.
Fixes#5502
Signed-off-by: Jordan Whited <jordan@tailscale.com>
25a0091f69