knxultimate/src/protocol/CRIFactory.ts

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

/**
 * Factory helpers for KNX CRI structures.
 *
 * 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 TunnelCRI from './TunnelCRI'

export default class CRIFactory {
	static createFromBuffer(buffer: Buffer, offset: number): any {
		if (offset >= buffer.length) {
			throw new Error('Buffer too short')
		}
		const structureLength: number = buffer.readUInt8(offset)
		if (offset + structureLength > buffer.length) {
			throw new Error('Buffer too short')
		}
		offset += 1
		const connectionType: number = buffer.readUInt8(offset++)
		switch (connectionType) {
			case KNX_CONSTANTS.TUNNEL_CONNECTION:
				return TunnelCRI.createFromBuffer(buffer, offset)
		}

		throw new Error('Unknown CRI type')
	}
}