knxultimate/src/protocol/KNXSearchResponse.ts

KNX IP protocol implementation for Node. This is the ENGINE of Node-Red KNX-Ultimate node.

/**
 * Parses KNX interface search responses.
 *
 * Written in Italy with love, sun and passion, by Massimo Saccani.
 *
 * Released under the MIT License.
 * Use at your own risk; the author assumes no liability for damages.
 */

import { KNX_CONSTANTS } from './KNXConstants'
import KNXPacket from './KNXPacket'
import DeviceInfo from './DeviceInfo'
import ServiceFamilies from './ServiceFamilies'
import HPAI from './HPAI'

export default class KNXSearchResponse extends KNXPacket {
	hpai: HPAI

	deviceInfo: DeviceInfo

	serviceFamilies: ServiceFamilies

	constructor(
		hpai: HPAI,
		deviceInfo: DeviceInfo,
		serviceFamilies: ServiceFamilies,
	) {
		super(
			KNX_CONSTANTS.SEARCH_RESPONSE,
			hpai.length + deviceInfo.length + serviceFamilies.length,
		)
		this.hpai = hpai
		this.deviceInfo = deviceInfo
		this.serviceFamilies = serviceFamilies
	}

	static createFromBuffer(
		buffer: Buffer,
		offset: number = 0,
	): KNXSearchResponse {
		const hpai = HPAI.createFromBuffer(buffer, offset)
		offset += hpai.length
		let deviceInfo: DeviceInfo
		let serviceFamilies: ServiceFamilies

		// Iterate over remaining blocks, pick DEVICE_INFO and SUPP_SVC_FAMILIES in any order
		let foundDevice = false
		let foundServices = false
		while (
			offset + 2 <= buffer.length &&
			(!foundDevice || !foundServices)
		) {
			const len = buffer.readUInt8(offset)
			if (len < 2 || offset + len > buffer.length) break
			const type = buffer.readUInt8(offset + 1)
			if (!foundDevice && type === KNX_CONSTANTS.DEVICE_INFO) {
				deviceInfo = DeviceInfo.createFromBuffer(buffer, offset)
				offset += deviceInfo.length
				foundDevice = true
				continue
			}
			if (!foundServices && type === KNX_CONSTANTS.SUPP_SVC_FAMILIES) {
				serviceFamilies = ServiceFamilies.createFromBuffer(
					buffer,
					offset,
				)
				offset += serviceFamilies.length
				foundServices = true
				continue
			}
			// skip unknown / unneeded DIB
			offset += len
		}

		if (!foundDevice) {
			throw new Error('KNXSearchResponse: DEVICE_INFO DIB not found')
		}
		if (!foundServices) {
			// create empty service families to avoid crashes
			serviceFamilies = new ServiceFamilies()
		}

		return new KNXSearchResponse(hpai, deviceInfo!, serviceFamilies!)
	}

	toBuffer(): Buffer {
		return Buffer.concat([
			this.header.toBuffer(),
			this.hpai.toBuffer(),
			this.deviceInfo.toBuffer(),
			this.serviceFamilies.toBuffer(),
		])
	}
}