domainfind: Add a script to find domains in TLDs given dictionaries

domainfind

@@ -0,0 +1,157 @@
+#! /bin/bash
+#
+# tldfind
+# Copyright (C) 2020 Vintage Salt <rehashedsalt@cock.li>
+#
+# Distributed under terms of the MIT license.
+#
+set -e
+
+# Read-only set-once variables
+declare -r _name="$(basename -- "$0")"
+# Options
+declare _optdict="/usr/share/dict/words"
+declare -i _opthelp
+declare -i _optverbose
+# Working variables
+declare -a _args
+declare _return
+
+# Helper functions
+log() {
+	# Print a line to the terminal if _optverbose is greater than $2
+	# $2 defaults to 0
+	# loglevel 0: Daily-use messages
+	# loglevel 1: Detailed but not quite debugging
+	# loglevel 2: Definitely debugging
+	[ -z "$1" ] && return 1
+	if (( _optverbose >= ${2:-0} )); then
+		printf "%s\\n" "$1"
+	fi
+}
+warn() {
+	# Print a yellow line to the terminal, respecting _optverbose
+	[ -z "$1" ] && return 1
+	if (( _optverbose >= ${2:-0} )); then
+		if [ -t 1 ]; then
+			printf "\\e[33m%s\\e[0m\\n" "$1"
+		else
+			printf "WARN: %s\\n" "$1"
+		fi
+	fi
+}
+error() {
+	# Print a red line to the terminal, exit if $2 is specified
+	[ -z "$1" ] && return 1
+	if [ -t 2 ]; then
+		printf "\\e[31m%s\\e[0m\\n" "$1" 1>&2
+	else
+		printf "ERROR: %s\\n" "$1" 1>&2
+	fi
+	[ -z "$2" ] && return
+	exit "${2:-1}"
+}
+has() {
+	# Parse out all arguments and try to find them in path
+	# If an argument cannot be found, set _return and fail
+	for prog in "$@"; do
+		if ! command -v "$prog" > /dev/null 2>&1; then
+			_return="$prog"
+			return 1
+		fi
+	done
+	return 0
+}
+
+# Core program functions
+printhelp() {
+	cat << EOF
+Usage: $_name [OPTION]... [TLD]...
+Find available domain names in the dictionary that are whole words ending in
+the given TLDs
+
+  -d [FILE]		A dictionary to load. Defaults to /usr/share/dict/words
+  -h			Print this help text
+  -v			Print more status messages. Stacks
+
+Copyright (c) 2020 rehashedsalt@cock.li
+Licensed under the MIT license
+EOF
+}
+checkavaildomains() {
+	[ -z "$1" ] && return 1
+	# Strip leading periods
+	tld="${1#.}"
+	while read word; do
+		! [[ $word == *$tld ]] && continue
+		log "Processing word: $word" 2
+		prefix="${word%$tld}"
+		fqdn="$prefix.$tld"
+		log "Looking for domain: $fqdn" 2
+		# We wait here so a ^C kills our program, not nslookup
+		nslookup "$fqdn" > /dev/null 2>&1 &
+		if ! wait -n; then
+			log "$fqdn"
+		fi
+	done < "$_optdict"
+}
+
+# Main
+main() {
+	# Parse out arguments
+	while [ -n "$1" ]; do
+		# Parse out flags
+		while getopts ":dhv" opt; do
+			case $opt in
+				d)
+					_optdict="$OPTARG"
+					;;
+				h)
+					_opthelp=1
+					;;
+				v)
+					_optverbose+=1
+					;;
+				:)
+					error "Option requires argument: -$OPTARG" 2
+					;;
+				*)
+					error "Invalid option: -$OPTARG" 2
+					;;
+			esac
+		done
+		# Store arguments
+		shift $((OPTIND - 1))
+		if [ -n "$1" ]; then
+			_args+=("$1")
+			shift
+		fi
+		unset OPTIND
+	done
+	# Early hook for help
+	[ -n "$_opthelp" ] && printhelp && exit 0
+	# Validate critical options
+	if ! [ -f "$_optdict" ]; then
+		error "Failed to find dictionary: $_optdict" 1
+	fi
+	# Validate core program dependencies
+	log "Validating dependencies" 2
+	if ! has basename; then
+		error "Failed to find program: $_return" 1
+	fi
+
+	# Do the do
+	if [ -n "${_args[*]}" ]; then
+		for arg in "${_args[@]}"; do
+			if ! checkavaildomains "$arg"; then
+				error "Error check domains for TLD: $arg"
+			fi
+		done
+	else
+		warn "Nothing to do"
+		exit 0
+	fi
+}
+
+main "$@"
+