翻出历史项目，先上传，未测试（MQTT3.1.1已经支持）

packet/connack.go

@@ -0,0 +1,127 @@
+package packet
+
+import (
+	"fmt"
+)
+
+type ConnackCode byte
+
+const (
+	CONNACK_ACCEPTED ConnackCode = iota
+	CONNACK_ERROR_VERSION
+	CONNACK_INVALID_CLIENT_ID
+	CONNACK_UNAVAILABLE
+	CONNACK_INVALID_USERNAME_PASSWORD
+	CONNACK_NOT_AUTHORIZED
+)
+
+type Connack struct {
+	Header
+
+	confirm byte
+	code    byte
+}
+
+func (msg *Connack) SessionPresent() bool {
+	return msg.confirm&0x01 == 0x01 //0000 0001
+}
+
+func (msg *Connack) SetSessionPresent(b bool) {
+	msg.dirty = true
+	if b {
+		msg.confirm |= 0x01 //0000 0001
+	} else {
+		msg.confirm &= 0xFE //1111 1110
+	}
+}
+
+func (msg *Connack) Code() ConnackCode {
+	return ConnackCode(msg.code)
+}
+
+func (msg *Connack) SetCode(c ConnackCode) {
+	msg.dirty = true
+	msg.code = byte(c)
+}
+
+func (msg *Connack) Decode(buf []byte) (int, error) {
+	msg.dirty = false
+
+	//Tips. remain length is fixed 2 & total is fixed 4
+	total := len(buf)
+	if total < 4 {
+		return 0, fmt.Errorf("Connack expect fixed 4 bytes (%d)", total)
+	}
+
+	offset := 0
+
+	//Header
+	msg.header = buf[0]
+	offset++
+
+	//Remain Length
+	if l, n, err := ReadRemainLength(buf[offset:]); err != nil {
+		return offset, err
+	} else if l != 2 {
+		return 0, fmt.Errorf("Remain length must be 2, got %d", l)
+	} else {
+		msg.remainLength = l
+		offset += n
+	}
+
+	//1 Confirm
+	msg.confirm = buf[offset]
+	offset++
+
+	//2 Code
+	msg.code = buf[offset]
+	offset++
+
+	// FixHead & VarHead
+	msg.head = buf[0:offset]
+
+	return offset, nil
+}
+
+func (msg *Connack) Encode() ([]byte, []byte, error) {
+	if !msg.dirty {
+		return msg.head, nil, nil
+	}
+
+	//Tips. remain length is fixed 2 & total is fixed 4
+	//Remain Length
+	msg.remainLength = 0
+	//Confirm
+	msg.remainLength += 1
+	//Code
+	msg.remainLength += 1
+
+	//FixHead & VarHead
+	hl := msg.remainLength
+
+	hl += 1 + LenLen(msg.remainLength)
+	//Alloc buffer
+	msg.head = make([]byte, hl)
+
+	//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
+	}
+
+	//1 Confirm
+	msg.head[ho] = msg.confirm
+	ho++
+
+	//2 Code
+	msg.head[ho] = msg.code
+	ho++
+
+	return msg.head, nil, nil
+}