From afd8272ac0a049d6b7da4b3370b476613ce9a3cf Mon Sep 17 00:00:00 2001
From: Case Duckworth
Date: Thu, 30 Apr 2020 15:45:19 -0500
Subject: Version 0.2

A LOT of changes here. Mostly I tried to make it more robust, and to
actually quit when I want it to quit. I also rewrote a lot of the
functions and stuff. I feel pretty happy with it now, enough to make it
an actual project on sourcehut.
---
 mrgrctrnl | 200 +++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 120 insertions(+), 80 deletions(-)

diff --git a/mrgrctrnl b/mrgrctrnl
index d51be58..796470c 100755
--- a/mrgrctrnl
+++ b/mrgrctrnl
@@ -1,95 +1,135 @@
 #!/bin/sh
-# mrgrctrnl
-# configurable ssh tunneler
-# by Case Duckworth <acdw@acdw.net>
-# version 0.1
-# LICENSE: MIT
+# mrgrctrnl: configurable ssh tunneler
+# Author: Case Duckworth <acdw@acdw.net>
+# Version: 0.2
+# License: MIT
 
-usage() {
-	cat <<-END
-		mrgrctrnl: make magic ssh tunnels
-		usage: mrgrctrnl [-h] [-c CONF] [-d] [-k]
+PRGN="${0##*/}"
 
-		-h       show this help
-		-c CONF use config file CONF.
-		.        default: \$XDG_CONFIG_HOME/mrgrctrnl/config
-		-d       do a dry run: don't actually tunnel
-		-k       kill all processes and exit
+usage() {
+	cat <<END
+$PRGN: make magic ssh tunnels
+usage:	$PRGN [-h] [-k]
+	$PRGN [-n] [-c CONF | -s SSH]
 
-	END
-	exit "${1:-0}"
+options:
+	-h	show this help
+	-k	kill all processes and exit
+	-r	restart $PRGN
+	-n	do a dry run: just print what would happen
+	-c CONFIG	use a different CONFIG file instead of
+			\$XDG_CONFIG_HOME/$PRGN/config
+	-s CMDLINE	directly input an ssh CMDLINE --
+			don't load the config file.
+END
 }
 
-die() {
-	[ "$#" -eq 0 ] && exit 1
-	case "$1" in
-	0-9*)
-		ec="$1"
-		shift
-		;;
-	*) ec=1 ;;
-	esac
-	printf '!!%s: %s\n' "mrgrctrnl" "$*"
-	exit "$ec"
-}
+# entry point
+main() {
+	__CONFIG="${XDG_CONFIG_HOME:-$HOME/.config}/$PRGN/config"
+	__SSHCMD="-N \"\$user@\$machine\" -L \"\$local:\$remote\""
+	__PIDF="/tmp/$PRGN.pid"
+	_run=true
+	_quiet=false
+	_use_config=true
 
-demolish_tunnels() {
-	printf '%s...' "Demolishing tunnels"
-	while read -r pid; do
-		[ -z "$pid" ] && continue
-		kill "$pid" 2>/dev/null
-	done <"$pidf"
-	rm "$pidf"
-	sleep 3
-	printf '%s.\n' "Done"
-}
+	while getopts hqkrnc:s: OPT; do
+		case "$OPT" in
+		h)
+			usage
+			exit 0
+			;;
+		q) _quiet=true ;;
+		k)
+			tear_down
+			pkill -x "$PRGN"
+			exit
+			;;
+		r)
+			tear_down
+			exec "$PRGN"
+			;;
+		n) _run=false ;;
+		c) __CONFIG="$OPTARG" ;;
+		s)
+			__SSHCMD="$OPTARG"
+			_use_config=false
+			;;
+		*)
+			usage
+			exit 1
+			;;
+		esac
+	done
 
-config="${XDG_CONFIG_HOME:=$HOME/.config}/mrgrctrnl/config"
-pidf=/tmp/mrgrctrnl.pid
-dry_run=false
+	if $_use_config && [ ! -r "$__CONFIG" ]; then
+		echo "!! $PRGN: Cannot find config file '$__CONFIG'."
+		echo "Aborting."
+		exit 2
+	fi
 
-while getopts hc:dk opt; do
-	case "$opt" in
-	h) usage ;;
-	c) config="$OPTARG" ;;
-	d) dry_run=true ;;
-	k)
-		demolish_tunnels
-		pkill -x mrgrctrnl
-		exit
-		;;
-	\?) usage 2 ;;
-	*) usage 2 ;;
-	esac
-done
-shift "$((OPTIND - 1))"
+	if $_use_config; then
+		awk '{sub(/#.*$/,"");print}' "$__CONFIG" |
+			while read -r machine user local remote key rest; do
+				if [ -z "$machine" ] || [ -z "$user" ] ||
+					[ -z "$local" ] || [ -z "$remote" ]; then
+					continue
+				fi
 
-[ -f "$config" ] || die "Need a config! Edit $config"
-if [ -e "$pidf" ] && ! "$dry_run"; then
-	demolish_tunnels
-fi
+				# shellcheck disable=2030
+				if [ -n "$key" ]; then
+					__SSHCMD="$__SSHCMD -i \"$key\""
+				fi
+				if [ -n "$rest" ]; then
+					__SSHCMD="$__SSHCMD $rest"
+				fi
 
-awk '{sub(/#.*$/,"");print}' "$config" |
-	while read -r machine user local remote key rest; do
-		if [ -z "$machine" ] || [ -z "$user" ] ||
-			[ -z "$local" ] || [ -z "$remote" ]; then
-			continue
-		fi
+				eval "tunnel $__SSHCMD" &
+			done
+	else
+		# shellcheck disable=2031
+		eval "tunnel $__SSHCMD" &
+	fi
 
-		set -- -N "$user@$machine" -L "$local:$remote"
-		[ -n "$key" ] && set -- "$@" -i "$key"
-		#shellcheck disable=2086
-		[ -n "$rest" ] && set -- "$@" $rest
+	wait
+}
 
-		echo ssh "$@"
+tunnel() {
+	# shellcheck disable=2086
+	$_quiet || echo ssh "$@"
+	$_run && {
+		touch "$__PIDF"
+		while [ -e "$__PIDF" ]; do
+			grep -q -e "$*" "$__PIDF" && {
+				sleep 3
+				continue
+			}
+			# shellcheck disable=2015
+			if ssh "$@" & then
+				printf '%s\t%s\n' "$!" "$*" >>"$__PIDF"
+			else
+				badpid="$!"
+				kill "$badpid"
+				sed "/^$badpid/d" "$__PIDF" >"$__PIDF~" &&
+					mv "$__PIDF~" "$__PIDF"
+				continue
+			fi
+			sleep 3
+		done
+	}
+}
 
-		"$dry_run" || {
-			while :; do
-				ssh "$@"
-				echo "$!" >>"$pidf"
-				sleep 5
-			done &
-		}
-	done
+tear_down() {
+	printf '%s...' "Killing extant tunnels"
+	if [ -e "$__PIDF" ]; then
+		while read -r pid _; do
+			kill "$pid" 2>/dev/null
+		done <"$__PIDF"
+		rm "$__PIDF"
+	else
+		pkill -x ssh
+	fi
+	echo Done.
+}
 
-wait
+main "$@"
-- 
cgit 1.4.1-21-gabe81