tunn

#!/bin/bash

# helper functions

tunn_check_op() {
	if [ "$OP" != "$1" ]; then
		usage 1
	fi
}

tunn_read() {
	# get list of tunnels
	readarray -t TLIST < "$CONFIG"
	export TLIST
}

tunn_entry() {
	ENTRY="${TLIST[$1]}"
	IFS=' ' read -r -a ENTRY_ARR <<< "$ENTRY"

	# reconstruct command based on output format
	export SOCKETNAME="${ENTRY_ARR[0]}"
	export PORT="${ENTRY_ARR[1]}"
	# gets last N-2 words
	export CMD="${ENTRY_ARR[*]: -$((${#ENTRY_ARR[@]}-2))}"
}

# operations

tunn_make() {
	CMD="$@"
	if [ -z "$CMD" ]; then
		usage 1
	fi

	# generate a random name for socket
	SOCKETNUM=$(uuidgen)
	SOCKETNAME="$NAMEPRE"_"$SOCKETNUM"

	# execute tunnel command
	eval $CMD -N -D $PORT -f -M -S "$SOCKETNAME" 2>/dev/null
	TEXIT=$?

	# add to list of tunnels
	if [ $TEXIT -eq 0 ]; then
		echo "$SOCKETNAME $PORT $CMD" >> "$CONFIG"
	else
		echo "Could not create tunnel (exit code $TEXIT)"
		exit $TEXIT
	fi
}

tunn_list() {
	if [ -n "$1" ]; then
		usage 1
	fi

	if [ -n "$UPDATE" ]; then
		tunn_read
		# clear list of tunnels
		: > "$CONFIG"
		# write open tunnels back into list
		for ((i=0; i < ${#TLIST[@]}; i++)); do
			tunn_entry $i
			if eval $CMD -S "$SOCKETNAME" -O check >&/dev/null; then
				echo "${TLIST[$i]}" >> "$CONFIG"
			else
				rm "$SOCKETNAME" >&/dev/null
			fi
		done
		unset TLIST
	fi

	tunn_read
	if [ ${#TLIST[@]} -eq 0 ]; then
		return
	fi
	echo "index: socket port command"
	for ((i=0; i < ${#TLIST[@]}; i++)); do
		echo "$i: ${TLIST[$i]}"
	done
}

tunn_kill() {
	INDEX="$1"
	if [ -z "$INDEX" ]; then
		usage 1
	fi

	# get this tunnel
	tunn_read
	if [ $INDEX -lt ${#TLIST[@]} ]; then
		tunn_entry $INDEX
	else
		echo "Tunnel index $INDEX not found"
		exit 2
	fi

	# execute kill command
	eval $CMD -S "$SOCKETNAME" -O exit

	# update list
	sed -i "$((INDEX+1))"d "$CONFIG"
}

# defaults
CONFIG=~/.tunnlist
USE_ALIASES=true
NAMEPRE=~/tsock
PORT=8864
SOCKETNAME=""
CMD=""
INDEX=""
UPDATE=""

usage() {
	ECHO="echo -e"
	$ECHO "tunn [operation] [options] [arguments]"
	$ECHO
	$ECHO "Operations:"
	$ECHO
	$ECHO "make       \t make new tunnel"
	$ECHO "\t-n [name]   \t tunnel socket name prefix (default: ${NAMEPRE})"
	$ECHO "\t-p [port]   \t tunnel port (default: $PORT)"
	$ECHO "\t[command]   \t ssh command to run when making tunnel (required)"
	$ECHO
	$ECHO "list       \t list open tunnels"
	$ECHO "\t-u       \t update list of tunnels (check status and remove closed ones)"
	$ECHO
	$ECHO "kill       \t kill specified tunnel"
	$ECHO "\t[index]       \t index of tunnel (required)"
	$ECHO
	$ECHO "Common options:"
	$ECHO "-A          \t disable loading of aliases"
	$ECHO "-h          \t print this message and exit"
	exit $1
}

# get operation
OP=$1
shift 1

OPFN=""
case "$OP" in
	make) OPFN=tunn_make
	;;
	list) OPFN=tunn_list
	;;
	kill) OPFN=tunn_kill
	;;
	*) usage 1
	;;
esac

while getopts "An:p:uh" opt; do
	case "$opt" in
		A) USE_ALIASES=""
		;;
		n) tunn_check_op make; NAMEPRE="$OPTARG"
		;;
		p) tunn_check_op make; PORT="$OPTARG"
		;;
		u) tunn_check_op list; UPDATE=true
		;;
		h) usage 0
		;;
	esac
done

# get ssh aliases
if [ -n "$USE_ALIASES" ]; then
	shopt -s expand_aliases
	source ~/.bashrc
fi

# get args for operation (if any)
shift $(($OPTIND - 1))

# execute operation
$OPFN "$@"