irr-asn2prefix

#!/bin/bash
#
# Copyright (c) 2022-2024 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}") [-h <host>] [-p <port>] [-4|-6]" \
              "<asn>"; }

declare mode=""
while getopts ":h:p:46" opts; do
  case "${opts}" in
    h) host=${OPTARG} ;;
    p) port=${OPTARG} ;;
    4) # shellcheck disable=SC2015
       [[ -z "${mode}" ]] && mode="g" || err "Can not combine -4 with -6" ;;
    6) # shellcheck disable=SC2015
       [[ -z "${mode}" ]] && mode="6" || err "Can not combine -6 with -4" ;;
    *) usage ;;
  esac
done
shift $((OPTIND-1))

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

# IRRd style TCP responses
#
# For a successful response returning data, the response is:
#
#   A<length>
#   <response content>
#   C
#
# The length is the number of bytes in the response, including the newline
# immediately after the response content. Different objects are part of one
# lock of response content, each object separated by a blank line.
#
# If the query was valid, but no entries were found, the response is:
#
#   C
#
# If the query was valid, but the primary key queried for did not exist:
#
#   D
#
# If the query was invalid:
#
#   F <error message>
#
# Reference: https://irrd.readthedocs.io/en/stable/users/queries/whois/

result="$(echo "!${mode:-g}${1}" | \
          nc -- "${host:-whois.radb.net}" "${port:-43}" 2>&1 || :)"

[[ "${result}" == "F "* ]] && err "${result/F /}"
[[ "${result}" == "D" ]] && err "Primary key does not exist"
[[ "${result}" == "C" ]] && err "No entries were found"

readarray -t lines <<< "${result}"
# shellcheck disable=SC2015
[[ ${#lines[@]} == 3 && "${lines[0]}" == "A"$((${#lines[1]} + 1)) && \
   "${lines[2]}" == "C" ]] && echo "${lines[1]}" || err "${result}"