pkt_ping.go

/*
 * Copyright Go-IIoT (https://github.com/goiiot)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package libmqtt

import "bytes"

var (
	PingReqPacket  = &pingReqPacket{}
	PingRespPacket = &pingRespPacket{}
)

// pingReqPacket is sent from a Client to the Server.
//
// It can be used to:
// 		1. Indicate to the Server that the Client is alive in the absence of any other Control Packets being sent from the Client to the Server.
// 		2. Request that the Server responds to confirm that it is alive.
// 		3. Exercise the network to indicate that the Network Connection is active.
//
// This Packet is used in Keep Alive processing
type pingReqPacket struct {
	BasePacket
}

func (p *pingReqPacket) Type() CtrlType {
	return CtrlPingReq
}

func (p *pingReqPacket) Bytes() []byte {
	if p == nil {
		return nil
	}

	w := new(bytes.Buffer)
	_ = p.WriteTo(w)
	return w.Bytes()
}

func (p *pingReqPacket) WriteTo(w BufferedWriter) error {
	if p == nil {
		return ErrEncodeBadPacket
	}

	switch p.Version() {
	case V311, V5:
		_ = w.WriteByte(CtrlPingReq << 4)
		return w.WriteByte(0x00)
	default:
		return ErrUnsupportedVersion
	}
}

// pingRespPacket is sent by the Server to the Client in response to
// a pingReqPacket. It indicates that the Server is alive.
type pingRespPacket struct {
	BasePacket
}

func (p *pingRespPacket) Type() CtrlType {
	return CtrlPingResp
}

func (p *pingRespPacket) Bytes() []byte {
	if p == nil {
		return nil
	}

	w := new(bytes.Buffer)
	_ = p.WriteTo(w)
	return w.Bytes()
}

func (p *pingRespPacket) WriteTo(w BufferedWriter) error {
	if p == nil {
		return ErrEncodeBadPacket
	}

	switch p.Version() {
	case V311, V5:
		_ = w.WriteByte(CtrlPingResp << 4)
		return w.WriteByte(0x00)
	default:
		return ErrUnsupportedVersion
	}
}