#!/bin/bash

# Konfiguration der Knoten
MYNODE=1
DEVICE=eth0
OTHERNODE=192.168.20.2

# Cluster-Konfiguration
CLUSTERIP=192.168.10.3
CLUSTERMAC=01:02:03:04:05:06
ONLINE=0

check_node () {
  ip link list dev $DEVICE | grep -q UP
  return $?
}

failover () {
  ip address delete $CLUSTERIP/24 dev $DEVICE
  echo "-$MYNODE" > /proc/net/ipt_CLUSTERIP/$CLUSTERIP
  ssh $OTHERNODE "echo '+$MYNODE' > /proc/net/ipt_CLUSTERIP/$CLUSTERIP"
}

recover () {
  ssh $OTHERNODE "echo '-$MYNODE' > /proc/net/ipt_CLUSTERIP/$CLUSTERIP"
  ip address add $CLUSTERIP/24 dev $DEVICE
  echo "+$MYNODE" > /proc/net/ipt_CLUSTERIP/$CLUSTERIP
}

# Knoten initialisieren
modprobe ipt_conntrack
ip address add $CLUSTERIP/24 dev $DEVICE
iptables -F INPUT
iptables -I INPUT -d $CLUSTERIP -i $DEVICE \
  -p icmp --icmp-type echo-request -j CLUSTERIP --new \
  --hashmode sourceip --clustermac $CLUSTERMAC \
  --total-nodes 2 --local-node $MYNODE

# Test, ob das Cluster-Interface funktioniert
ONLINE=1
while (true); do
  if ( check_node ) then
    echo "Interface up"
    if [ $ONLINE -eq 0 ]; then
      recover
      ONLINE=1
    fi
  else
    echo "Interface down"
    if [ $ONLINE -eq 1 ]; then
      failover
      ONLINE=0
    fi
  fi
  sleep 1
done

exit 0