#!/bin/sh
#
# /etc/network/if-up.d/reachable
# /etc/network/if-down.d/reachable
#
# Specify reachable destination networks inside
# an interface stanca:
#
# iface eth2
#   address 10.0.0.1
#   netmask 255.255.255.255
#   reachable 10.0.0.2 10.0.0.3
#   reachable-foo 10.0.0.2 10.0.0.3
#   reachable-bar 10.0.0.4 10.0.0.5
#   # subnet reachable via Gateway
#   reachable-baz via 10.0.0.2 10.0.0.128/25
#
# Stefan Tomanek <stefan.tomanek@wertarbyte.de>
# http://wertarbyte.de/debian/

CMD_IP=/bin/ip

if [ ! -x $CMD_IP ]; then
  exit 0
fi

if [ "$MODE" = "start" ]; then
  OP="add"
else
  OP="del"
fi

REACHABLE="$(/usr/bin/awk 'BEGIN {
    for (key in ENVIRON) {
        if (key ~ /^IF_REACHABLE(_|$)/) {
            split(ENVIRON[key], A);
            GW="";
            if (A[1] == "via") {
                GW=A[2];
                delete A[1];
                delete A[2];
            }
            for (j in A) {
                print A[j], GW;
            }
        }
    }
}')"

# Nothing to do?
if [ -z "$REACHABLE" ]; then
    exit 0
fi

echo "$REACHABLE" | while read DEST GW; do
  [ -n "$GW" ] && RPATH="via $GW" || RPATH="dev $IFACE";
  FULL_CMD="$CMD_IP route $OP $DEST $RPATH"
  $FULL_CMD || \
  echo "Error executing: $FULL_CMD" >&2
done