Merge branch 'master' of github.com:thekhanj/salsa

Author: TheKhanj

bin/salsa

@@ -0,0 +1,151 @@
+#!/usr/bin/env bash
+
+PID=$$
+PROC_DIR="/var/run/salsa/$PID"
+[ "$USER" != 'root' ] && PROC_DIR="/run/user/$(id -u)/salsa/$PID"
+SLEEP_INTERVAL=5
+CHECK_PROXY=
+PROXIES_ADDRESS=()
+LISTENING_ADDRESS=
+HELP=0
+
+help() {
+	exec man salsa
+}
+
+error() {
+	echo "$1" >&2
+}
+
+parse_args() {
+	while [ $# -gt 0 ]; do
+		case "$1" in
+		'-l')
+			LISTENING_ADDRESS="$2"
+			shift 2
+			;;
+		'-t')
+			SLEEP_INTERVAL="$2"
+			shift 2
+			;;
+		'-c')
+			CHECK_PROXY="$2"
+			shift 2
+			;;
+		'-h' | '--help')
+			HELP=1
+			shift
+			;;
+		*)
+			PROXIES_ADDRESS+=("$1")
+			shift
+			;;
+		esac
+	done
+}
+
+validate_proxy_address() {
+	local address="$1"
+
+	[ -z "$address" ] && {
+		error 'empty proxy address.'
+		exit 3
+	}
+	echo "$address" |
+		grep -E '^(([0-9a-z]+\.)*[0-9a-z]+|([0-9]{1,3}\.){3}[0-9]{1,3})?:[0-9]{1,5}$' >/dev/null ||
+		{
+			error "invalid proxy address. ($address)"
+			exit 3
+		}
+}
+
+validate_input() {
+	for address in "${PROXIES_ADDRESS[@]}"; do
+		validate_proxy_address "$address"
+	done
+
+	[ -z "$LISTENING_ADDRESS" ] && help
+
+	echo "$LISTENING_ADDRESS" |
+		grep -E '^(([0-9]{1,3}\.){3}[0-9]{1,3})?:[0-9]{1,5}$' >/dev/null ||
+		{
+			error "invalid listening address. ($LISTENING_ADDRESS)"
+			exit 1
+		}
+
+	echo "$SLEEP_INTERVAL" |
+		grep '^[0-9]\+$' >/dev/null ||
+		{
+			error "invalid sleep interval. ($SLEEP_INTERVAL)"
+			exit 2
+		}
+}
+
+get_host() {
+	local ret="$(echo "$1" |
+		grep -oP '^(([0-9a-z]+\.)*[0-9a-z]+|([0-9]{1,3}\.){3}[0-9]{1,3})?')"
+
+	[ -z "$ret" ] && echo -n '0.0.0.0' || echo -n "$ret"
+}
+
+get_port() {
+	echo "$1" |
+		grep -oP '(?<=:)[0-9]{1,5}$'
+}
+
+check_proxy() {
+	local proxy="$1"
+
+	[ -z "$CHECK_PROXY" ] && {
+		local port="$(get_port "$proxy")"
+		ss -tnlp | grep :$port >/dev/null
+		return $?
+	}
+
+	$CHECK_PROXY "$proxy"
+}
+
+check_proxies() {
+	while true; do
+		for proxy in "${PROXIES_ADDRESS[@]}"; do
+			if check_proxy "$proxy"; then
+				[ -f "$PROC_DIR/${proxy}.unhealthy" ] && {
+					echo "proxy $proxy is back up"
+					rm "${PROC_DIR}/${proxy}.unhealthy"
+				}
+			else
+				[ -f "$PROC_DIR/${proxy}.unhealthy" ] || {
+					echo "proxy $proxy is down"
+					touch "${PROC_DIR}/${proxy}.unhealthy"
+				}
+			fi
+		done
+
+		sleep $SLEEP_INTERVAL
+	done
+}
+
+parse_args "$@"
+validate_input
+
+[ $HELP -eq 1 ] && help
+
+mkdir -p "$PROC_DIR"
+
+listening_host="$(get_host "$LISTENING_ADDRESS")"
+listening_port="$(get_port "$LISTENING_ADDRESS")"
+
+error "process id is $PID"
+error "listening on address $listening_host:$listening_port"
+printf "forwarding requests to proxies %s\n" "${PROXIES_ADDRESS[@]}"
+
+command="salsa-handler '$PROC_DIR' '${PROXIES_ADDRESS[@]}'"
+
+check_proxies &
+CHECK_PROXIES_PID=$!
+
+socat TCP-LISTEN:$listening_port,bind=$listening_host,fork,reuseaddr,forever \
+	EXEC:"$command"
+
+kill -9 $CHECK_PROXIES_PID
+rm -rf $PROC_DIR