#!/usr/bin/env bash

# Bash Finger client using /dev/tcp (shell I/O, slower than direct socket calls)
# Supports 8-bit characters, long files, ASCII art

# License:   Blue Oak Model License 1.0.0
# Copyright: https://640kb.neocities.org

# 09 Jul 2026: Added finger://domain.com format support; improved trap handling
# 24 Jun 2026: Help section, help flags, removed version numbers
# 14 Nov 2025: Fixed help flags
# 11 Oct 2025: 128k Transfer limit as default, minor other edits
# 30 May 2025: Added Transfer limit (BFINGER_MAX_BYTES) & timeouts
# 01 May 2025: Initial release

# ------------------------------ Start Script -------------------------------

set -eo pipefail

[ -n "${DEBUG:-}" ] && set -xu  

VERSION="09 Jul 2026"

export LC_ALL=C

cleanup() {
  exec 3<&- 3>&- 2>/dev/null || true
  exit 130
}
trap cleanup INT TERM EXIT

# Transfer limit: default is ~128KB. Adjust as needed.
MAX_BYTES=${BFINGER_MAX_BYTES:-128000}

if [ $# -eq 0 ] || [[ "$1" =~ ^(-h|--help)$ ]]; then
  echo ""
  echo " .-------------------------------------------------------------------------."
  echo " | bfinger - A Bash-based Finger Client ($VERSION)                      |"
  echo " |                                                                         |"
  echo " | Uses Bash's /dev/tcp for socket connections to query remote Finger      |"
  echo " | servers. Full support for 8-bit characters, long files and ASCII art.   |"
  echo " | ----------------------------------------------------------------------- |"
  echo " | Usage:                                                                  |"
  echo " |   bfinger @domain.com                # Queries host                     |"
  echo " |   bfinger user@domain.com            # Specific user                    |"
  echo " |   bfinger finger://domain.com/user   # URL format                       |"
  echo " |   bfinger @localhost                 # when fingerd installed locally   |"
  echo " | ----------------------------------------------------------------------- |"
  echo " | Options:                                                                |"
  echo " |   -v, --version                      Show version info                  |"
  echo " |   -h, --help                         Show this help message             |"
  echo " | ----------------------------------------------------------------------- |"
  echo " | Examples:                                                               |"
  echo " |   bfinger originsfinger@happynetbox.com | less                          |"
  echo " |   bfinger @plan.cat | head -n 20                                        |"
  echo " |   bfinger finger://happynetbox.com/originsfinger                        |"
  echo " | ----------------------------------------------------------------------- |"
  echo " | Compatibility: Linux, macOS, *BSD                                       |"
  echo " '-------------------------------------------------------------------------'"
  echo ""
  exit 0
fi

if [[ "${1:-}" == "--version" || "${1:-}" == "-v" ]]; then
  echo
  echo "bfinger - A Bash-based finger client ($VERSION)"
  echo
  exit 0
fi

if [[ "$1" == finger://* ]]; then
  path="${1#finger://}"
  if [[ "$path" == */* ]]; then
    HOST="${path%%/*}"
    USER="${path#*/}"
  else
    HOST="$path"
    USER=""
  fi
elif [[ "$1" == @* ]]; then
  USER=""
  HOST="${1#@}"
elif [[ "$1" =~ @ ]]; then
  USER="${1%%@*}"
  HOST="${1##*@}"
else
  echo "Error: Invalid format. Use user@domain.com, @domain.com, or finger://domain.com/user" >&2
  exit 1
fi

PORT=79

if [ -z "$HOST" ]; then
  echo "Error: No host specified" >&2
  exit 1
fi

if [[ ! "$HOST" =~ ^[a-zA-Z0-9._-]+$ ]]; then
  echo "Error: Hostname contains invalid characters" >&2
  exit 1
fi

if ! getent hosts "$HOST" >/dev/null; then
  echo "Error: Host '$HOST' could not be resolved" >&2
  exit 1
fi

if ! timeout 5 bash -c "exec 3<>/dev/tcp/$HOST/$PORT"; then
  echo "Error: Connection to $HOST:$PORT timed out or failed" >&2
  echo "Tip: Try 'telnet $HOST $PORT' to debug" >&2
  exit 1
fi
exec 3<>/dev/tcp/"$HOST"/"$PORT"

printf "%s\r\n" "$USER" >&3

bytes_read=0
while IFS= read -r -t 5 -N 1 char <&3 && (( bytes_read++ < MAX_BYTES )); do
  printf "%s" "$char"
done
(( bytes_read >= MAX_BYTES )) && echo >&2
(( bytes_read >= MAX_BYTES )) && echo "Output truncated after $MAX_BYTES bytes." >&2

exec 3<&- 3>&-