55 lines
1.7 KiB
TypeScript
55 lines
1.7 KiB
TypeScript
import { MAX_DATA_LENGTH } from '../common'
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import { numberToUint16BE } from '../utilities/number'
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import { SmartBuffer } from '../utilities/smart-buffer'
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export interface IncomingPacket {
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messageType: number
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senderId: number
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data: Uint8Array
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}
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export interface OutgoingPacket {
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messageType: Uint8Array
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data: Uint8Array
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}
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/**
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* Create an outgoing packet ready-to-send over a WebSocket in line with the BENNC basic message strucure specification.
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* @param outgoingPacket The message type and data to send.
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* @returns A buffer containing the ready-to-send packet.
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*/
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export function packOutgoingPacket (outgoingPacket: OutgoingPacket): Uint8Array {
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// Verify that the data does not exceed the maximum data length.
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if (outgoingPacket.data.length > MAX_DATA_LENGTH) {
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throw RangeError(`Specified data of length ${outgoingPacket.data.length} exceeds max data length ${MAX_DATA_LENGTH}.`)
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}
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// Prepare the outgoing packet.
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const buffer = new SmartBuffer()
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buffer.writeBytes(outgoingPacket.messageType)
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buffer.writeBytes(numberToUint16BE(outgoingPacket.data.length))
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buffer.writeBytes(outgoingPacket.data)
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return buffer.data
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}
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/**
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* Unpack an incoming packet coming from a WebSocket in line with the BENNC basic message strucure specification.
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* @param incomingPacket The incoming buffer from a WebSocket to unpack.
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* @returns The unpacked data.
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*/
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export function unpackIncomingPacket (incomingPacket: ArrayBuffer): IncomingPacket {
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const buffer = SmartBuffer.from(incomingPacket)
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const messageType = buffer.readUInt16()
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const senderId = buffer.readUInt32()
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const length = buffer.readUInt16()
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const data = buffer.readBytes(length)
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return {
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messageType: messageType,
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senderId: senderId,
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data: data
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}
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}
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