#! /bin/bash
#
# nfs - start NFS in response to interface change
#
# Bastian Senst <bholst@lusku.de>

function net_umount {
    umount -l -f $1 &>/dev/null
}

function net_mount {
    mountpoint -q $1 || mount $1
}

function test_reach {
    if [ "$(ip link show up $1)" = "" ]; then
        return 1
    else 
        ping -n -c1 -w2 -I "$1" "$2" 2>&1 > /dev/null
    fi
}

DEVICE="$1"
COMMAND="$2"

function test_other_reaches {
    for other in $(ls /sys/class/net); do
        if [[ "$other" != "$DEVICE" ]]; then 
            if test_reach "$other" "$1"; then
                return 0
            fi
        fi
    done
    return 1
}

declare -A reaches

function other_reaches {
    if [[ "${reaches[$1]-}" == "yes" ]]; then
        return 0
    elif [[ "${reaches[$1]-}" == "no" ]]; then
        return 1
    else
        if test_other_reaches $1; then
            reaches[$1]="yes"
            return 0
        else 
            reaches[$1]="no"
            return 1
        fi
    fi
}

NET_MOUNTS=$(sed -e '/^.*#/d' -e '/^.*:/!d' -e 's/\t/ /g' -e '/x-systemd.automount/d' /etc/fstab | tr -s " ")$'\n'

case "$COMMAND" in
    up|dhcp4-change|dhcp6-change)
        # Check with systemd if nfs service is enabled
        if /usr/bin/systemctl is-enabled nfs-client.target >/dev/null 2>&1; then
            printf %s "$NET_MOUNTS" | while IFS= read -r line; do
                MOUNT_OPTIONS=$(echo $line | cut -f4 -d" ")
                MOUNT_POINT=$(echo $line | cut -f2 -d" ")
                FS_TYPE=$(echo $line | cut -f3 -d" ")
                # Only mount it if not "noauto "set in options
                case ",${MOUNT_OPTIONS}," in
                    *,noauto,*) continue ;;
                esac
                # Only mount it when the type is nfs or nfs4
                if [ "$FS_TYPE" == "nfs" -o "$FS_TYPE" == "nfs4" ]; then
                    net_mount "$MOUNT_POINT"
                fi
            done
        fi
        ;;
    pre-down|down|vpn-pre-down)
        printf %s "$NET_MOUNTS" | while IFS= read -r line; do
            [[ $line ]] || continue
            MOUNT_POINT=$(echo $line | cut -f2 -d" ")
            FS_TYPE=$(echo $line | cut -f3 -d" ")
            HOST=$(echo $line |  cut -f1 -d":")
            if other_reaches $HOST; then
                echo >&2 "Other network interfaces reach $HOST for $MOUNT_POINT."
            else
                # Only unmount it when the type is nfs or nfs4
                if [ "$FS_TYPE" == "nfs" -o "$FS_TYPE" == "nfs4" ]; then
                    net_umount "$MOUNT_POINT"
                fi
            fi
        done
        exit 0
        ;;
    *)
        exit 0
        ;;
esac