rir-geofeed2prefix

#!/bin/bash
#
# Copyright (c) 2024 Nagrind <https://github.com/nagrind>
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#

set -euo pipefail

err() { echo "${@}" 1>&2; exit 1; }
usage() { err "Usage: $(basename "${0}") [-4|-6] <geofeed>"; }

declare mode=""
while getopts ":46" opts; do
  case "${opts}" in
    4) mode+="\." ;;
    6) mode+=":" ;;
    *) usage ;;
  esac
done
shift $((OPTIND-1))

[[ ${#} != 1 ]] && usage

result="$(curl --silent --user-agent "rir-geofeed2prefix/0.0.1" -- "${1}" | \
  gawk -F ',' '{ if (!/^#/ && tolower($1) ~ /^[0-9a-f].*['"${mode:-\.:}"']/) \
    print $1 }')"

readarray -t lines <<< "${result}"
# shellcheck disable=SC2015
[[ ${#lines[@]} != 0 && -n "${lines[0]}" ]] && echo "${result}" || \
  err "No entries found"