翻出历史项目，先上传，未测试（MQTT3.1.1已经支持）

packet/suback.go

@@ -0,0 +1,127 @@
+package packet
+
+import (
+	"encoding/binary"
+)
+
+type SubCode byte
+
+const (
+	SUB_CODE_QOS0 SubCode = iota
+	SUB_CODE_QOS1
+	SUB_CODE_QOS2
+	SUB_CODE_ERR = 128
+)
+
+type SubAck struct {
+	Header
+
+	packetId uint16
+
+	codes []byte
+}
+
+func (msg *SubAck) PacketId() uint16 {
+	return msg.packetId
+}
+
+func (msg *SubAck) SetPacketId(p uint16) {
+	msg.dirty = true
+	msg.packetId = p
+}
+
+func (msg *SubAck) Codes() []byte {
+	return msg.codes
+}
+
+func (msg *SubAck) AddCode(c SubCode) {
+	msg.dirty = true
+	msg.codes = append(msg.codes, byte(c))
+}
+
+func (msg *SubAck) ClearCode() {
+	msg.dirty = true
+	msg.codes = msg.codes[0:0]
+}
+
+func (msg *SubAck) Decode(buf []byte) (int, error) {
+	msg.dirty = false
+
+	//total := len(buf)
+	offset := 0
+
+	//Header
+	msg.header = buf[0]
+	offset++
+
+	//Remain Length
+	if l, n, err := ReadRemainLength(buf[offset:]); err != nil {
+		return offset, err
+	} else {
+		msg.remainLength = l
+		offset += n
+	}
+	headerLen := offset
+
+	// PacketId
+	msg.packetId = binary.BigEndian.Uint16(buf[offset:])
+	offset += 2
+
+	// FixHead & VarHead
+	msg.head = buf[0:offset]
+	//plo := offset
+
+	// Parse Codes
+	l := msg.remainLength + headerLen
+	msg.codes = buf[offset:l]
+
+	//Payload
+	msg.payload = msg.codes
+
+	return offset, nil
+}
+
+func (msg *SubAck) Encode() ([]byte, []byte, error) {
+	if !msg.dirty {
+		return msg.head, msg.payload, nil
+	}
+
+	//Remain Length
+	msg.remainLength = 0
+	//Packet Id
+	msg.remainLength += 2
+
+	//FixHead & VarHead
+	hl := msg.remainLength
+
+	//Codes
+	msg.remainLength += len(msg.codes)
+
+	//pl := msg.remainLength - hl
+	hl += 1 + LenLen(msg.remainLength)
+
+	//Alloc buffer
+	msg.head = make([]byte, hl)
+	//msg.payload = make([]byte, pl)
+
+	//Header
+	ho := 0
+	msg.head[ho] = msg.header
+	ho++
+
+	//Remain Length
+	if n, err := WriteRemainLength(msg.head[ho:], msg.remainLength); err != nil {
+		return nil, nil, err
+	} else {
+		ho += n
+	}
+
+	//Packet Id
+	binary.BigEndian.PutUint16(msg.head[ho:], msg.packetId)
+	ho += 2
+
+	//Codes
+	msg.payload = msg.codes
+
+	return msg.head, msg.payload, nil
+}