154 lines
3.8 KiB
Go
154 lines
3.8 KiB
Go
package load
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import (
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"bytes"
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"fmt"
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"io"
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"github.com/mochi-mqtt/server/v2/packets"
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)
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const (
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mqttProtocolLevel5 = 5
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mqttKeepaliveSec = 30
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)
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// encodeConnect 按 DEVELOPMENT §5 生成 MQTT 5 CONNECT：
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// ClientID=Username=端编号、CleanStart、心跳 30、会话过期间隔缺省为 0（Clean Start 时即为 0）。
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// 不声明 Receive Maximum，避免踩 mochi 发送配额路径。
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func encodeConnect(endpointID, password string) ([]byte, error) {
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pk := packets.Packet{
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FixedHeader: packets.FixedHeader{Type: packets.Connect},
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ProtocolVersion: mqttProtocolLevel5,
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Connect: packets.ConnectParams{
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ProtocolName: []byte("MQTT"),
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Clean: true,
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ClientIdentifier: endpointID,
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Keepalive: mqttKeepaliveSec,
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UsernameFlag: true,
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Username: []byte(endpointID),
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PasswordFlag: true,
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Password: []byte(password),
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},
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}
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var buf bytes.Buffer
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if err := pk.ConnectEncode(&buf); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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func encodeSubscribe(packetID uint16, endpointID string) ([]byte, error) {
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pk := packets.Packet{
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FixedHeader: packets.FixedHeader{Type: packets.Subscribe, Qos: 1},
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ProtocolVersion: mqttProtocolLevel5,
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PacketID: packetID,
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Filters: packets.Subscriptions{
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{Filter: downTopic(endpointID), Qos: 1},
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},
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}
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var buf bytes.Buffer
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if err := pk.SubscribeEncode(&buf); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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func encodePublish(packetID uint16, endpointID string, payload []byte) ([]byte, error) {
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pk := packets.Packet{
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FixedHeader: packets.FixedHeader{Type: packets.Publish, Qos: 1},
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ProtocolVersion: mqttProtocolLevel5,
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TopicName: upTopic(endpointID),
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PacketID: packetID,
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Payload: payload,
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}
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var buf bytes.Buffer
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if err := pk.PublishEncode(&buf); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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func encodePuback(packetID uint16) ([]byte, error) {
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pk := packets.Packet{
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FixedHeader: packets.FixedHeader{Type: packets.Puback},
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ProtocolVersion: mqttProtocolLevel5,
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PacketID: packetID,
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}
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var buf bytes.Buffer
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if err := pk.PubackEncode(&buf); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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func encodePingreq() []byte {
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return []byte{0xC0, 0x00}
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}
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func downTopic(id string) string { return "nix/c/" + id + "/down" }
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func upTopic(id string) string { return "nix/c/" + id + "/up" }
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func connackReason(raw []byte) (byte, error) {
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if len(raw) < 2 || raw[0]>>4 != packets.Connack {
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return 0, fmt.Errorf("不是 CONNACK：type=0x%02x len=%d", byteAt(raw, 0), len(raw))
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}
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rem, n, err := decodeRemainingLength(raw[1:])
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if err != nil {
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return 0, err
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}
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body := raw[1+n:]
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if rem < 2 || len(body) < 2 {
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return 0, fmt.Errorf("CONNACK 过短 remaining=%d body=%d", rem, len(body))
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}
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return body[1], nil
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}
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func decodePublish(raw []byte) (payload []byte, packetID uint16, qos byte, err error) {
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if len(raw) < 2 {
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return nil, 0, 0, io.ErrUnexpectedEOF
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}
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qos = (raw[0] >> 1) & 0x3
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rem, n, err := decodeRemainingLength(raw[1:])
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if err != nil {
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return nil, 0, 0, err
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}
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body := raw[1+n:]
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if len(body) != rem {
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return nil, 0, 0, io.ErrUnexpectedEOF
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}
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pk := packets.Packet{
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ProtocolVersion: mqttProtocolLevel5,
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FixedHeader: packets.FixedHeader{
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Type: packets.Publish,
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Remaining: rem,
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Qos: qos,
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},
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}
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if err := pk.PublishDecode(body); err != nil {
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return nil, 0, qos, err
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}
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return pk.Payload, pk.PacketID, qos, nil
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}
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func decodeRemainingLength(b []byte) (value int, n int, err error) {
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var mul uint32 = 1
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var v uint32
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for i := 0; i < len(b) && i < 4; i++ {
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v += uint32(b[i]&127) * mul
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n++
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if b[i]&128 == 0 {
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return int(v), n, nil
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}
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mul *= 128
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}
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return 0, 0, io.ErrUnexpectedEOF
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}
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func byteAt(b []byte, i int) byte {
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if i < 0 || i >= len(b) {
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return 0
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}
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return b[i]
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}
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