import { BufferReader , BufferWriter } from "@node-lightning/bufio" ; import { PONG_BYTE_THRESHOLD } from "../Constants" ; import { MessageType } from "../MessageType" ; import { IWireMessage } from "./IWireMessage" ; /**
 * In order to allow for the existence of long-lived TCP
 * connections,  at times it may be required that both ends keep
 * alive the TCP connection at the application level.
 *
 * The ping message is sent by an initiator and includes a value
 * for the number of pong bytes it expects to receive as
 * a reply. The ignored bits should be set to 0.
 */ export class PingMessage implements IWireMessage { /**
     * Deserialize a message and return a new instance of the
     * PingMessage type.
     */ public static deserialize ( payload ) { const cursor = new BufferReader ( payload ) ; cursor . readUInt16BE ( ) ; const instance = new PingMessage ( ) ; instance . numPongBytes = cursor . readUInt16BE ( ) ; const bytesLength = cursor . readUInt16BE ( ) ; instance . ignored = cursor . readBytes ( bytesLength ) ; return instance ; } /**
     * Ping message type is 18
     */ public type : MessageType = MessageType . Ping ; /**
     * The number of bytes that should be returned in the pong message.
     * Can be set to 65532 to indicate that no pong message should be
     * sent. Setting to any number below 65532 will require a pong
     * matching the corresponding number of bytes. If the reply
     * byteslen does not match this, you may terminate the channels
     * with the client.
     */ public numPongBytes : number = 1 ; /**
     * Should set ignored to 0s. Must not set ignored to
     * sensitive data such as secrets or portions of initialized
     * memory.
     */ public ignored : Buffer = Buffer . alloc ( 0 ) ; /**
     * Serialize the PingMessage and return a Buffer
     */ public serialize ( ) { const len = 2 + 2 + 2 + this . ignored . length ; const br = new BufferWriter ( Buffer . alloc ( len ) ) ; br . writeUInt16BE ( this . type ) ; br . writeUInt16BE ( this . numPongBytes ) ; br . writeUInt16BE ( this . ignored . length ) ; br . writeBytes ( this . ignored ) ; return br . toBuffer ( ) ; } /**
     * triggersReply indicates if a pong message must send a reply.
     * Ping messages than are smaller than 65532 must send a reply
     * with the corresponding number of bytes. Above this value
     * no reply is necessary.  Refer to BOLT #1.
     */ public get triggersReply ( ) : boolean { return this . numPongBytes < PONG_BYTE_THRESHOLD ; } }