#!/bin/sh -e

create_hosts_file() {
if [ -e /etc/hosts ]; then return 0; fi

cat > /etc/hosts <<-EOF
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

EOF
}

create_networks_file() {
if [ -e /etc/networks ]; then return 0; fi

cat > /etc/networks <<-EOF
default 0.0.0.0
loopback 127.0.0.0
link-local 169.254.0.0

EOF
}

# create bindv6only.conf on new installs and upgrades from << 4.38
create_bindv6only_conf() {
if [ -e /etc/sysctl.d/bindv6only.conf ]; then
return 0
fi
[ "$(uname -s)" = "Linux" ] || return 0
[ -d /etc/sysctl.d/ ] || mkdir /etc/sysctl.d/
if [ "$2" ] && dpkg --compare-versions "$2" ge "4.38"; then
return 0
fi

cat >> /etc/sysctl.d/bindv6only.conf <<-EOF
# This sysctl sets the default value of the IPV6_V6ONLY socket option.
#
# When disabled, IPv6 sockets will also be able to send and receive IPv4
# traffic with addresses in the form ::ffff:192.0.2.1 and daemons listening
# on IPv6 sockets will also accept IPv4 connections.
#
# When IPV6_V6ONLY is enabled, daemons interested in both IPv4 and IPv6
# connections must open two listening sockets.
# This is the default behaviour of almost all modern operating systems.

net.ipv6.bindv6only = 1
EOF
}

case "$1" in
configure)
if [ -z "$2" ]; then
create_hosts_file
create_networks_file
fi
#create_bindv6only_conf "$@"
;;

abort-upgrade|abort-remove|abort-deconfigure)
;;

*)
echo "postinst called with unknown argument '$1'" >&2
exit 1
;;
esac