debian-initramfs-ipv6-premount-script

#!/bin/sh
# Script to be placed in /etc/initramfs-tools/scripts/init-premount/ipv6

PREREQ=""
prereqs()
{
    echo "$PREREQ"
}

parse_options()
{
    v6opts="$1"
    echo "v6opts='$v6opts'"

    addr=""
    gw=""
    iface=""
    ll=""
    accept_ra=0
    forwarding=0

    IFS=","
    for opt in $v6opts; do
        case $opt in
            addr=*)
                addr=${opt#addr=}
                ;;
            gw=*)
                gw=${opt#gw=}
                ;;
            iface=*)
                iface=${opt#iface=}
                ;;
            accept_ra=*)
                iface=${opt#accept_ra=}
                ;;
            ll=*)
                ll=${opt#ll=}
                ;;
            forwarding=*)
                forwarding=${opt#forwarding=}
                ;;
        esac
    done
    if [ ! -d "/proc/sys/net/ipv6/conf/${iface}" ]; then
        log_failure_msg "IPv6: Interface ${iface} not found, sorry."
        return 0
    fi

    log_begin_msg "IPv6: Setup IPv6 on ${iface}"
    echo "${accept_ra}" > "/proc/sys/net/ipv6/conf/${iface}/accept_ra"
    echo "${forwarding}" > "/proc/sys/net/ipv6/conf/${iface}/forwarding"
    if [ -n "${ll}" ]; then
        /sbin/ip -6 address flush dev "${iface}"
        /sbin/ip -6 address add "${ll}" scope link dev "${iface}"
    fi
    /sbin/ip link set "${iface}" up
    /sbin/ip -6 address add "${addr}" dev "${iface}"
    if [ -n "${gw}" ]; then
        /sbin/ip -6 route del default
        /sbin/ip -6 route add default via "${gw}" dev "${iface}"
    fi
    log_end_msg

    return 0
}

case $1 in
# get pre-requisites
prereqs)
    prereqs
    exit 0
    ;;
esac

for arg in $(cat /proc/cmdline); do
    case ${arg} in
        ipv6=*)
            # syntax: ipv6=addr=<address>/<netmask>,gw=<gateway>,iface=<interface>,forwarding=<0/1>,accept_ra=<0/1/2>
            # colons are not used as delimiters due to them being in use in ipv6 addrs
            parse_options "${arg#ipv6=}"
            ;;
    esac
done