multihomed-routing-ifup

#!/bin/bash

handle_nm_ifup()
{
    echo "$(env)" >> /tmp/nm-env.log
    echo "\n" >> /tmp/nm-env.log
    for ((i=0; i < IP4_NUM_ADDRESSES; i++))
    do
        varname="IP4_ADDRESS_$i"
        addr_str=$(echo ${!varname} | cut -d " " -f 1)
        network_address=$(echo "$addr_str" | cut -d "/" -f 1)

        if [ -n "$DHCP4_SUBNET_MASK" ];
        then
            network_number=$DHCP4_NETWORK_NUMBER
            netmask=$DHCP4_SUBNET_MASK;
        else
            netmask=$(ipcalc $addr_str | grep Netmask | tr -d " " | cut -d ":" -f 2 | cut -d "=" -f 1)
            network_number=$(ipcalc "$addr_str" | grep "^Network" | tr -d " " | cut -d ":" -f 2 | cut -d "/" -f 1)
        fi

        #get route
        rt_table=$(/usr/sbin/table_allocator_client -4 -s -a "$network_address" -n "$netmask" -i "$IFACE" -d tas_socket)

        if [ "$rt_table" -eq 0 ];
        then
            rt_table=254;
            if_metric=$(/sbin/ip link show dev "$IFACE" | head -1 | cut -d " " -f 1 | cut -d ":" -f 1)
        fi

        #move the address route created by default
        #ip -4 ro delete ${network_number}${netmask:+/$netmask} dev ${IFACE}
        ip -4 ro add ${network_number}${netmask:+/$netmask} dev ${IFACE} \
            src ${network_address} table ${rt_table} ${if_metric:+metric $if_metric}

        #move default route to table
        #ip -4 ro delete default via ${IP4_GATEWAY} dev ${IFACE}
        ip -4 ro add default via ${IP4_GATEWAY} dev ${IFACE} src ${network_address} \
            table ${rt_table} ${if_metric:+metric $if_metric}

        #move other provided routes
        for ((j=0; j < IP4_NUM_ROUTES; j++))
        do
            varname="IP4_ROUTE_$i"
            route_address=$(echo ${!varname} | cut -d " " -f 1)
            route_next_hop=$(echo ${!varname} | cut -d " " -f 2)
            route_metric=$(echo ${!varname} | cut -d " " -f 3)

            #ip -4 ro delete ${route_address} via ${route_next_hop} dev ${IFACE} \
            #    ${route_metric:+metric $route_metric}
            ip -4 ro add ${route_address} via ${route_next_hop} dev ${IFACE} \
                ${route_metric:+metric $route_metric} table ${rt_table} \
                src ${network_address}
        done
    done
}

handle_ifup()
{
    #get route
    rt_table=$(/usr/sbin/table_allocator_client -4 -s -a "$IF_ADDRESS" -n "$IF_NETMASK" -i "$IFACE" -d tas_socket)

    if [ "$rt_table" -eq 0 ];
    then
        rt_table=254;
        if_metric=$(/sbin/ip link show dev "$IFACE" | head -1 | cut -d " " -f 1 | cut -d ":" -f 1)
    fi

    #This is not the nicest way in the world to extract network number, look into
    #bash bitwise operators when time
    network_number=$(ipcalc "$IF_ADDRESS"/"$IF_NETMASK" | grep "^Network" | tr -d " " |
    cut -d ":" -f 2 | cut -d "/" -f 1)

    #we are run from up, static configuration is already applied

    #move the address route created by default
    ip -4 ro delete ${network_number}${IF_NETMASK:+/$IF_NETMASK} dev ${IFACE}
    ip -4 ro add ${network_number}${IF_NETMASK:+/$IF_NETMASK} dev ${IFACE} \
        src ${IF_ADDRESS} table ${rt_table} ${if_metric:+metric $if_metric}

    #move default route to table
    ip -4 ro delete default via ${IF_GATEWAY} dev ${IFACE}
    ip -4 ro add default via ${IF_GATEWAY} dev ${IFACE} src ${IF_ADDRESS} \
        table ${rt_table} ${if_metric:+metric $if_metric}
}

if [ "$ADDRFAM" != "inet" ];
then
    exit 0;
fi

if [ "$METHOD" = "NetworkManager" -a "$IP4_GATEWAY" ];
then
    handle_nm_ifup
elif [ "$METHOD" = "static" -a -n "$IF_GATEWAY" ];
then
    handle_ifup
fi

exit 0