First Commit

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diff --git a/README.md b/README.md
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+# `vpnswitch(1)`
+
+Automatically switch VPN based on internal network connectivity, similar to DirectAccess.
+
+## Configuration
+
+Refer to `profile` for more details.
+
+## License
+
+WTFPL
diff --git a/profile b/profile
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+# The command to check if this computer is connected to the internal network.
+# Return codes:
+#  - 0: This computer is in the internal network.
+#       vpnswitch(1) will then execute CHECK_VPN_CMD, and stop the VPN if needed.
+#  - 1: This computer is NOT in the internal network.
+#       vpnswitch(1) will then execute CHECK_VPN_CMD, and start the VPN if needed.
+#  - [2, 255]: An error occured. Abort the whole execution.
+#       vpnswitch(1) will exit with the same return code.
+# This command is usually ping(1) or curl(1).
+# Mandatory value.
+CHECK_NETWORK_CMD="ping -c 3 10.0.1.200"
+
+# The command to check if this computer is connected to the internal network, with VPN already on.
+# This command is only ran if CHECK_VPN_CMD returns 0.
+# Refer to CHECK_NETWORK_CMD for documentation.
+# Mandatory value. It can be simply $CHECK_NETWORK_CMD.
+CHECK_NETWORK_CMD_VPN="ping -c 2 10.0.3.1"
+
+# Specifies the timeout CHECK_NETWORK_CMD runs in seconds.
+# After the specified seconds:
+#  - CHECK_NETWORK_CMD will be killed using SIGTERM
+#  - The computer will be considered NOT in the internal network, thus starting the VPN.
+# Specifing 0 or not specifing this value will not set a timeout for CHECK_NETWORK_CMD.
+# However, it is the administrator's responsibility to not let vpnswitch(1) stucking.
+# Optional value.
+CHECK_NETWORK_TIMEOUT=5
+
+# The command to check if the VPN is already running.
+# Return codes:
+#  - 0: VPN is running.
+#       If CHECK_NETWORK_CMD returns 0 (in the internal network), VPN_DOWN_CMD will be executed.
+#  - 1: VPN is NOT running.
+#       If CHECK_NETWORK_CMD returns 1 (NOT in the internal network), VPN_UP_CMD will be executed.
+#  - [2, 255]: An error occured. Abort the whole execution.
+#       vpnswitch(1) will exit with the same return code.
+# Mandatory value.
+CHECK_VPN_CMD="ip a s dev sea1us"
+
+# The command to start the VPN and anything else depending on the VPN.
+# Return codes:
+#  - 0: The VPN is successfully started or requested to start.
+#       It is the administrator's responsibility to make sure the VPN started.
+#  - [1, 255]: An error occured. Abort the whole execution.
+#       vpnswitch(1) will exit with the same return code.
+# This command is executed when:
+#  - CHECK_NETWORK_CMD returns 1 (NOT in the ineternal network), AND
+#  - CHECK_VPN_CMD     returns 1 (VPN is NOT running).
+# Mandatory value.
+VPN_UP_CMD="echo Up"
+
+# The command to stop the VPN and anything else depending on the VPN.
+# Return codes:
+#  - 0: The VPN is successfully stopped or requested to stopped.
+#       It is the administrator's responsibility to make sure the VPN stopped.
+#  - [1, 255]: An error occured. Abort the whole execution.
+#       vpnswitch(1) will exit with the same return code.
+# This command is executed when:
+#  - CHECK_NETWORK_CMD returns 0 (in the ineternal network), AND
+#  - CHECK_VPN_CMD     returns 0 (VPN is running).
+# Mandatory value.
+VPN_DOWN_CMD="echo Down"
diff --git a/vpnswitch b/vpnswitch
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+#!/bin/sh
+set -e
+
+alias echoe=">&2 echo"
+
+## Debug setup
+
+# To be overrided by DEBUG
+function dbg() {
+	:
+}
+
+if ! test -z ${DEBUG+x}; then
+	set -x
+	function dbg() {
+		echoe $1
+	}
+fi
+
+## End debug setup
+
+## Util functions
+
+# Check if a variable named $1 is set. If not, apply the default value at $2.
+# If no default value is supplied, prompt an error and exit with 64.
+function check_var() {
+	local _var=$1
+	local _t=$(eval "\${$_var+echo ' '}")
+	if test -z "$_t"; then
+		if test "$#" -eq 2; then
+			eval "$_var=$2"
+			dbg "Setting variable '$_var' to default value '$1'"
+		else
+			echoe "Required variable: '$_var' is missing in the profile."
+			exit 64
+		fi
+	fi
+}
+
+function run_test() {
+	local _cmd=$@
+	dbg "Running '$_cmd' ..."
+	if _out=$($_cmd); then
+		echo "$_out"
+		return 0
+	else
+		local _exit=$?
+		echo "$_out"
+		if test $_exit -eq 124; then
+			case $_cmd in
+				"timeout"*)
+					echoe "Command '$_cmd' timed out."
+					return 1
+					;;
+				*)
+					;;
+			esac
+		fi
+		case $_exit in
+			1)
+				return 1
+				;;
+			*)
+				echo "Command '$_cmd' exited with abnormal code: $_exit."
+				exit $_exit
+				;;
+		esac
+	fi
+}
+
+## End util functions
+
+## Main
+
+if test "$#" -ne 1; then
+	echoe "Usage: $0 [Profile]"
+	exit 64
+fi
+PROFILE=$1
+if test -e "$PROFILE"; then
+	dbg "Using profile from path $PROFILE"
+	. $PROFILE
+else
+	. /etc/vpnswitch/$PROFILE.conf
+fi
+
+check_var CHECK_NETWORK_CMD
+check_var CHECK_NETWORK_CMD_VPN
+check_var CHECK_NETWORK_TIMEOUT 0
+if test $CHECK_NETWORK_TIMEOUT -lt 0; then
+	echoe "\$CHECK_NETWORK_TIMEOUT must be greater or equals than 0, but it is currently set to $CHECK_NETWORK_TIMEOUT."
+	exit 64
+fi
+check_var CHECK_VPN_CMD
+check_var VPN_UP_CMD
+check_var VPN_DOWN_CMD
+
+## Gather information
+if _out=$(run_test $CHECK_VPN_CMD); then
+	echo "$_out"
+	echo "VPN running:		yes"
+	IN_VPN=0
+	dbg "Using CHECK_NETWORK_CMD_VPN when VPN is running."
+	CHECK_NETWORK_CMD=$CHECK_NETWORK_CMD_VPN
+else
+	echo "$_out"
+	echo "VPN running:		no"
+	IN_VPN=1
+fi
+
+if test $CHECK_NETWORK_TIMEOUT -gt 0; then
+	CHECK_NETWORK_CMD="timeout -s SIGTERM ${CHECK_NETWORK_TIMEOUT}s $CHECK_NETWORK_CMD"
+fi
+if _out=$(run_test $CHECK_NETWORK_CMD); then
+	echo "$_out"
+	echo "Internal network:	yes"
+	IN_NET=0
+else
+	echo "$_out"
+	echo "Internal network:	no"
+	IN_NET=1
+fi
+
+## Start / stop VPN
+if test $IN_NET -eq 1; then         # Not in internal network
+	if test $IN_VPN -eq 1; then # VPN not running
+		dbg "Starting VPN by running '$VPN_UP_CMD'"
+		exec $VPN_UP_CMD
+	else                        # VPN is running
+		exit 0
+	fi
+else                                # In internal network
+	if test $IN_VPN -eq 1; then # VPN not running
+		exit 0
+	else                        # VPN is running
+		dbg "Stopping VPN by running '$VPN_UP_CMD'"
+		exec $VPN_DOWN_CMD
+	fi
+fi