protocol_fetch() {
    local url file RETVAL i server remote_file
    url="$1"
    file="$2"
    server="$(echo $url | cut -d/ -f 3)"
    remote_file="/$(echo $url | cut -d/ -f 4-)"
    RETVAL=0
    for i in 1 2; do
        tftp -g -l "$file" -r "$remote_file" "$server" || RETVAL=$?
        [ $RETVAL = 1 ] || return $RETVAL
        [ "$TRY_REPEAT" ] || break
    done
    return $RETVAL
}