bot.sh

#!/usr/bin/env bash
# Based on kekbot by dom, Aatrox, and Hunner from the CAT @ Portland State University.

syntax='Usage: MCBE_Bot.sh [OPTION] ...'

input() {
	# $USER, $HOSTNAME, and $fqdn are verified, name is clearly not
	# $USER = `whoami` and is not set in cron
	echo "USER $(whoami) $HOSTNAME $fqdn :The Mafia"
	echo "NICK $nick"
	echo "$join"
	# Last 10 lines of $buffer as IRC appends to it
	tail -f "$buffer"
}

ping_timeout() {
	diff=0
	# 15 minute timeout
	# irc.cat.pdx.edu ping timeout is 4m20s
	while [ "$diff" -lt 900 ]; do
		sleep 1
		# Seconds since epoch
		thyme=$(date +%s)
		# File modification time in seconds since epoch
		mthyme=$(stat -c %Y "$ping_time")
		diff=$((thyme - mthyme))
	done
	>&2 echo Ping timeout
	# Kill session processes of $$ (script PID)
	# exit doesn't exit script when backgrounded
	pkill -s $$
	exit 1
}

send() {
	# Avoid filename expansion
	echo "$*" >> "$buffer"
}

args=$(getopt -l help,instance: -o hi: -- "$@")
eval set -- "$args"
while [ "$1"  != -- ]; do
	case $1 in
	--help|-h)
		echo "$syntax"
		echo Minecraft Bedrock Edition server IRC bot
		echo
		echo Mandatory arguments to long options are mandatory for short options too.
		echo '-i, --instance=INSTANCE  use configuration file ~/.MCBE_Bot/{INSTANCE}Join.txt. defaults to MCBE_Bot.'
		echo
		echo 'See README.md for format of ~/.MCBE_Bot/{INSTANCE}Join.txt'
		exit
		;;
	--instance|-i)
		instance=$2
		shift 2
		;;
	esac
done
shift

if [ "$#" -gt 0 ]; then
	>&2 echo Too much arguments
	>&2 echo "$syntax"
	exit 1
fi

# If $instance doesn't exist
if [ -z "$instance" ]; then
	instance=MCBE_Bot
fi
# Make directory and parents quietly
mkdir -p /bedrock-server/MCBE_Bot
buffer=/bedrock-server/MCBE_Bot/${instance}Buffer
# Kill all doppelgangers
# Duplicate bots exit if $buffer is removed
rm -f "$buffer"
mkfifo "$buffer"
chmod 600 "$buffer"
ping_time=/bedrock-server/MCBE_Bot/${instance}Ping
touch "$ping_time"

join_file=/bedrock-server/MCBE_Bot/${instance}Join.txt
chmod 600 "$join_file"
join=$(grep -Ev '^[^ ]+:[0-9]+$' "$join_file")
if ! server=$(grep -E '^[^ ]+:[0-9]+$' "$join_file"); then
	echo "No server in $join_file"
	exit 1
fi
if echo "$join" | grep -q '^NICK '; then
	nick=$(echo "$join" | grep '^NICK ' | cut -d ' ' -f 2 -s)
	join=$(echo "$join" | grep -v '^NICK ')
else
	nick=$instance
fi

# DNS check
# Trim off $server after first :
if ! stdout=$(host "${server%%:*}"); then
	>&2 echo "$stdout"
	exit 1
fi
fqdn=$(host "$HOSTNAME" | head -n 1 | cut -d ' ' -f 1)

ping_timeout &

input | openssl s_client -connect "$server" 2>&1 | while read -r irc; do
	# If disconnected MCBE_Bot reads an empty string
	if [ -n "$irc" ]; then
		# Reset timeout
		touch "$ping_time"
		echo "$irc"
		if [ "$(echo "$irc" | cut -d ' ' -f 1)" = PING ]; then
			send PONG
		elif [[ "$(echo "$irc" | cut -d ' ' -f 1)" =~ connect:errno=[0-9]+ ]]; then
			pkill -s $$
			exit 1
		fi
	fi
done