#!/bin/sh

#set -e

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

case $1 in
    prereqs)
        prereqs
        exit 0
        ;;
esac

[ -x /bin/tailscale ] || exit 0

. /scripts/functions

PIDFILE="/run/tailscale.pid"

if [ -e /etc/tailscale/initramfs/config ]; then
    . /etc/tailscale/initramfs/config
fi

if [ -z "${TAILSCALE_HOSTNAME-}" ]; then
    if [ -f /etc/tailscale/initramfs/hostname ]; then
        HOSTNAME=$(cat /etc/tailscale/initramfs/hostname)
    else
        HOSTNAME=$(hostname -s)
    fi

    TAILSCALE_HOSTNAME=${HOSTNAME}-initramfs
fi

network_up()
{
    for conf in /run/net-*.conf /run/net6-*.conf; do
        if [ -e "$conf" ]; then
            # shellcheck disable=SC1090
            . "$conf"
            return 0
        fi
    done
    return 1
}

# shellcheck disable=SC3043
create_resolv_conf()
{
    if [ -e /etc/resolv.conf ]; then
        return
    fi

    local ns
    for ns in "${IPV4DNS0:-}" "${IPV4DNS1:-}" "${IPV6DNS0:-}" "${IPV6DNS1:-}"; do
        if [ -n "$ns" ] && [ "$ns" != "0.0.0.0" ]; then
            echo "nameserver $ns" >> /etc/resolv.conf
        fi
    done

    if [ -e /etc/resolv.conf ]; then
        return
    fi

    for ns in ${FALLBACK_DNS_SERVERS:-}; do
        if [ -n "$ns" ]; then
            echo "nameserver $ns" >> /etc/resolv.conf
        fi
    done
}

# shellcheck disable=SC2039,SC2086,SC3043
run_tailscale()
{
    log_begin_msg "Starting tailscale"

    local options="--state=/var/lib/tailscale/tailscaled.state --socket=/run/tailscale/tailscaled.sock"

    # FIXME: This races with dropbear-initramfs bringing up the network
    # asynchronously
    if [ "$BOOT" != nfs ]; then
        # Keep trying to bring up the network until it's up
        # or the boot process continues toward finish.
        while true; do
            # "." builtin (in dash) exits on error. Run configure_networking
            # in a subshell and wait for it.
            configure_networking &
            wait $!
            if ! [ -e "$PIDFILE" ]; then
                break
            fi
            if network_up; then
                create_resolv_conf
                break
            fi
        done
    fi

    # A little race-y to start the client before the daemon, but the client
    # will attempt to connect to the socket for a while.
    # https://github.com/tailscale/tailscale/blob/8cf1af8a0703c36256fc58e98ddb63b8907848f1/safesocket/safesocket.go#L119-L122
    /bin/tailscale --socket=/run/tailscale/tailscaled.sock up --authkey="${TAILSCALE_AUTHKEY}" --hostname="${TAILSCALE_HOSTNAME}" $TAILSCALE_OPTIONS &

    if [ "${debug:-}" != y ]; then
        exec 2>/run/initramfs/tailscale.log
    fi
    exec /sbin/tailscaled $options $TAILSCALED_OPTIONS
}

[ "$BOOT" = nfs ] && configure_networking

modprobe tun
run_tailscale &
echo $! > "$PIDFILE"

exit 0