added changes to address security loophole in the IFTTT app

addressed comments

PENG-157 IFTTT should not allow undefined commands
- added changes to address security loophole in the IFTTT app
- addressed comments
- removed an extra whitespace

smartapps/smartthings/ifttt.src/ifttt.groovy

@@ -131,19 +131,69 @@ def update() {
 	def type = params.deviceType
 	def data = request.JSON
 	def devices = settings[type]
+	def device = settings[type]?.find { it.id == params.id }
 	def command = data.command
 
 	log.debug "[PROD] update, params: ${params}, request: ${data}, devices: ${devices*.id}"
-	if (command) {
-		def device = devices?.find { it.id == params.id }
-		if (!device) {
-			httpError(404, "Device not found")
-		} else {
-			device."$command"()
-		}
+	
+	if (!device) {
+		httpError(404, "Device not found")
+	} 
+	
+	if (validateCommand(device, type, command)) {
+		device."$command"()
+	} else {
+		httpError(403, "Access denied. This command is not supported by current capability.")
 	}
 }
 
+/**
+ * Validating the command passed by the user based on capability.
+ * @return boolean
+ */
+def validateCommand(device, deviceType, command) {
+	def capabilityCommands = getDeviceCapabilityCommands(device.capabilities)
+	def currentDeviceCapability = getCapabilityName(deviceType)
+	if (capabilityCommands[currentDeviceCapability]) {
+		return command in capabilityCommands[currentDeviceCapability] ? true : false
+	} else {
+		// Handling other device types here, which don't accept commands
+		httpError(400, "Bad request.")
+	}
+}
+
+/**
+ * Need to get the attribute name to do the lookup. Only
+ * doing it for the device types which accept commands
+ * @return attribute name of the device type
+ */
+def getCapabilityName(type) {
+    switch(type) {
+		case "switches":
+			return "Switch"
+		case "alarms":
+			return "Alarm"
+		case "locks":
+			return "Lock"
+		default:
+			return type
+	}
+}
+
+/**
+ * Constructing the map over here of
+ * supported commands by device capability
+ * @return a map of device capability -> supported commands
+ */
+def getDeviceCapabilityCommands(deviceCapabilities) {
+	def map = [:]
+	deviceCapabilities.collect {
+		map[it.name] = it.commands.collect{ it.name.toString() }
+	}
+	return map
+}
+
+
 def show() {
 	def type = params.deviceType
 	def devices = settings[type]