packet

lib/message/connack.go

@@ -0,0 +1,168 @@
+// Copyright (c) 2014 The SurgeMQ Authors. All rights reserved.
+//
+// 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 message
+
+import "fmt"
+
+// The CONNACK Packet is the packet sent by the Server in response to a CONNECT Packet
+// received from a Client. The first packet sent from the Server to the Client MUST
+// be a CONNACK Packet [MQTT-3.2.0-1].
+//
+// If the Client does not receive a CONNACK Packet from the Server within a reasonable
+// amount of time, the Client SHOULD close the Network Connection. A "reasonable" amount
+// of time depends on the type of application and the communications infrastructure.
+type ConnackMessage struct {
+	header
+
+	sessionPresent bool
+	returnCode     ConnackCode
+}
+
+var _ Message = (*ConnackMessage)(nil)
+
+// NewConnackMessage creates a new CONNACK message
+func NewConnackMessage() *ConnackMessage {
+	msg := &ConnackMessage{}
+	msg.SetType(CONNACK)
+
+	return msg
+}
+
+// String returns a string representation of the CONNACK message
+func (this ConnackMessage) String() string {
+	return fmt.Sprintf("%s, Session Present=%t, Return code=%q\n", this.header, this.sessionPresent, this.returnCode)
+}
+
+// SessionPresent returns the session present flag value
+func (this *ConnackMessage) SessionPresent() bool {
+	return this.sessionPresent
+}
+
+// SetSessionPresent sets the value of the session present flag
+func (this *ConnackMessage) SetSessionPresent(v bool) {
+	if v {
+		this.sessionPresent = true
+	} else {
+		this.sessionPresent = false
+	}
+
+	this.dirty = true
+}
+
+// ReturnCode returns the return code received for the CONNECT message. The return
+// type is an error
+func (this *ConnackMessage) ReturnCode() ConnackCode {
+	return this.returnCode
+}
+
+func (this *ConnackMessage) SetReturnCode(ret ConnackCode) {
+	this.returnCode = ret
+	this.dirty = true
+}
+
+func (this *ConnackMessage) Len() int {
+	if !this.dirty {
+		return len(this.dbuf)
+	}
+
+	ml := this.msglen()
+
+	if err := this.SetRemainingLength(int32(ml)); err != nil {
+		return 0
+	}
+
+	return this.header.msglen() + ml
+}
+
+func (this *ConnackMessage) Decode(src []byte) (int, error) {
+	total := 0
+
+	n, err := this.header.decode(src)
+	total += n
+	if err != nil {
+		return total, err
+	}
+
+	b := src[total]
+
+	if b&254 != 0 {
+		return 0, fmt.Errorf("connack/Decode: Bits 7-1 in Connack Acknowledge Flags byte (1) are not 0")
+	}
+
+	this.sessionPresent = b&0x1 == 1
+	total++
+
+	b = src[total]
+
+	// Read return code
+	if b > 5 {
+		return 0, fmt.Errorf("connack/Decode: Invalid CONNACK return code (%d)", b)
+	}
+
+	this.returnCode = ConnackCode(b)
+	total++
+
+	this.dirty = false
+
+	return total, nil
+}
+
+func (this *ConnackMessage) Encode(dst []byte) (int, error) {
+	if !this.dirty {
+		if len(dst) < len(this.dbuf) {
+			return 0, fmt.Errorf("connack/Encode: Insufficient buffer size. Expecting %d, got %d.", len(this.dbuf), len(dst))
+		}
+
+		return copy(dst, this.dbuf), nil
+	}
+
+	// CONNACK remaining length fixed at 2 bytes
+	hl := this.header.msglen()
+	ml := this.msglen()
+
+	if len(dst) < hl+ml {
+		return 0, fmt.Errorf("connack/Encode: Insufficient buffer size. Expecting %d, got %d.", hl+ml, len(dst))
+	}
+
+	if err := this.SetRemainingLength(int32(ml)); err != nil {
+		return 0, err
+	}
+
+	total := 0
+
+	n, err := this.header.encode(dst[total:])
+	total += n
+	if err != nil {
+		return 0, err
+	}
+
+	if this.sessionPresent {
+		dst[total] = 1
+	}
+	total++
+
+	if this.returnCode > 5 {
+		return total, fmt.Errorf("connack/Encode: Invalid CONNACK return code (%d)", this.returnCode)
+	}
+
+	dst[total] = this.returnCode.Value()
+	total++
+
+	return total, nil
+}
+
+func (this *ConnackMessage) msglen() int {
+	return 2
+}