maeqtt/mqtt/packets/Subscriptions.go

package packets

import (
	"bufio"
	"errors"
	"io"

	"badat.dev/maeqtt/v2/mqtt/properties"
	"badat.dev/maeqtt/v2/mqtt/types"
)

type TopicFilter struct {
	Topic             string
	MaxQoS            uint
	NoLocal           bool
	RetainAsPublished bool
	RetainHandling    uint
}

func parseTopicFilter(r *bufio.Reader) (TopicFilter, error) {
	filter := TopicFilter{}
	var err error

	filter.Topic, err = types.DecodeUTF8String(r)
	if err != nil {
		return filter, err
	}

	options, err := types.DecodeBits(r)
	if err != nil {
		return filter, err
	}
	filter.MaxQoS = types.BoolsToUint(options[0], options[1])
	filter.NoLocal = options[2]
	filter.RetainAsPublished = options[3]
	filter.RetainHandling = types.BoolsToUint(options[4], options[5])
	return filter, nil
}

// Both sub and unsubscribe packets are identitcal so we can reuse the parsing logic
type SubscriptionPacket struct {
	PacketId     uint16
	TopicFilters []TopicFilter
}

func parseSubscriptionPacket(control controlPacket, props []properties.Property) (SubscriptionPacket, error) {
	var err error
	r := bufio.NewReader(control.reader)
	packet := SubscriptionPacket{}

	if control.flags != 2 {
		return packet, errors.New("Malformed subscription packet")
	}

	packet.PacketId, err = types.DecodeUint16(r)
	if err != nil {
		return packet, err
	}

	err = properties.ParseProperties(r, props)
	if err != nil {
		return packet, err
	}

	for err != io.EOF {
		filter, err := parseTopicFilter(r)
		packet.TopicFilters = append(packet.TopicFilters, filter)
		if err != nil {
			return packet, err
		}
		_, err = r.Peek(1)
		if err != nil || err != io.EOF {
			return packet, err
		}
	}

	return packet, nil
}

type SubscribePacket struct {
	*SubscriptionPacket
	props properties.SubscribePacketProperties
}

func parseSubscribePacket(control controlPacket) (SubscribePacket, error) {
	if control.packetType != PacketTypeSubscribe {
		panic("Wrong packet type for parseSubscribePacket")
	}

	pack := SubscribePacket{}
	subscriptionPack, err := parseSubscriptionPacket(control, pack.props.ArrayOf())
	if err != nil {
		return pack, err
	}
	pack.PacketId = subscriptionPack.PacketId
	pack.TopicFilters = subscriptionPack.TopicFilters
	return pack, nil
}

type SubackReasonCode byte

const (
	SubackReasonGrantedQoSZero         PubackReasonCode = 0
	SubackReasonGrantedQoSOne                           = 1
	SubackReasonGrantedQoSTwo                           = 2
	SubackReasonUnspecified                             = 128
	SubackReasonImplSpecificError                       = 131
	SubackReasonNotAuthorized                           = 135
	SubackReasonTopicFilterInvalid                      = 143
	SubackReasonPacketIDInUse                           = 145
	SubackReasonQuotaExceeded                           = 151
	SubackReasonSharedSubNotSupported                   = 151
	SubackReasonSubIDUnsupported                        = 151
	SubackReasonWildcardSubUnsupported                  = 151
)

type SubAckPacket struct {
	PacketID   uint16
	Properties properties.SubackPacketProperties
	Reason     SubackReasonCode 
}


func (p SubAckPacket) Write(w io.Writer) error {
	resp := pubRespPacket{
		PacketType: PacketTypeSuback,
		PacketID:   p.PacketID,
		Properties: p.Properties.ArrayOf(),
		Reason:     byte(p.Reason),
	}
	return resp.Write(w)
}

type UnsubscribePacket struct {
	*SubscriptionPacket
	props properties.UnsubscribePacketProperties
}

func parseUnsubscribePacket(control controlPacket) (UnsubscribePacket, error) {
	if control.packetType != PacketTypeUnsubscribe {
		panic("Wrong packet type for parseSubscribePacket")
	}

	pack := UnsubscribePacket{}
	subscriptionPack, err := parseSubscriptionPacket(control, pack.props.ArrayOf())
	if err != nil {
		return pack, err
	}
	pack.PacketId = subscriptionPack.PacketId
	pack.TopicFilters = subscriptionPack.TopicFilters
	return pack, nil
}

type UnsubackReasonCode byte

const (
	UnsubackReasonSuccess         PubackReasonCode = 0
	UnSubackReasonUnspecified                             = 128
	UnSubackReasonImplSpecificError                       = 131
	UnSubackReasonNotAuthorized                           = 135
	UnSubackReasonTopicFilterInvalid                      = 143
	UnSubackReasonPacketIDInUse                           = 145
)

type UnsubAckPacket struct {
	PacketID   uint16
	Properties properties.UnsubackPacketProperties
	Reason     UnsubackReasonCode
}


func (p UnsubAckPacket) Write(w io.Writer) error {
	resp := pubRespPacket{
		PacketType: PacketTypeUnsuback,
		PacketID:   p.PacketID,
		Properties: p.Properties.ArrayOf(),
		Reason:     byte(p.Reason),
	}
	return resp.Write(w)
}