packet

lib/message/publish.go

@@ -0,0 +1,250 @@
+// 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"
+	"sync/atomic"
+)
+
+// A PUBLISH Control Packet is sent from a Client to a Server or from Server to a Client
+// to transport an Application Message.
+type PublishMessage struct {
+	header
+
+	topic   []byte
+	payload []byte
+}
+
+var _ Message = (*PublishMessage)(nil)
+
+// NewPublishMessage creates a new PUBLISH message.
+func NewPublishMessage() *PublishMessage {
+	msg := &PublishMessage{}
+	msg.SetType(PUBLISH)
+
+	return msg
+}
+
+func (this PublishMessage) String() string {
+	return fmt.Sprintf("%s, Topic=%q, Packet ID=%d, QoS=%d, Retained=%t, Dup=%t, Payload=%v",
+		this.header, this.topic, this.packetId, this.QoS(), this.Retain(), this.Dup(), this.payload)
+}
+
+// Dup returns the value specifying the duplicate delivery of a PUBLISH Control Packet.
+// If the DUP flag is set to 0, it indicates that this is the first occasion that the
+// Client or Server has attempted to send this MQTT PUBLISH Packet. If the DUP flag is
+// set to 1, it indicates that this might be re-delivery of an earlier attempt to send
+// the Packet.
+func (this *PublishMessage) Dup() bool {
+	return ((this.Flags() >> 3) & 0x1) == 1
+}
+
+// SetDup sets the value specifying the duplicate delivery of a PUBLISH Control Packet.
+func (this *PublishMessage) SetDup(v bool) {
+	if v {
+		this.mtypeflags[0] |= 0x8 // 00001000
+	} else {
+		this.mtypeflags[0] &= 247 // 11110111
+	}
+}
+
+// Retain returns the value of the RETAIN flag. This flag is only used on the PUBLISH
+// Packet. If the RETAIN flag is set to 1, in a PUBLISH Packet sent by a Client to a
+// Server, the Server MUST store the Application Message and its QoS, so that it can be
+// delivered to future subscribers whose subscriptions match its topic name.
+func (this *PublishMessage) Retain() bool {
+	return (this.Flags() & 0x1) == 1
+}
+
+// SetRetain sets the value of the RETAIN flag.
+func (this *PublishMessage) SetRetain(v bool) {
+	if v {
+		this.mtypeflags[0] |= 0x1 // 00000001
+	} else {
+		this.mtypeflags[0] &= 254 // 11111110
+	}
+}
+
+// QoS returns the field that indicates the level of assurance for delivery of an
+// Application Message. The values are QosAtMostOnce, QosAtLeastOnce and QosExactlyOnce.
+func (this *PublishMessage) QoS() byte {
+	return (this.Flags() >> 1) & 0x3
+}
+
+// SetQoS sets the field that indicates the level of assurance for delivery of an
+// Application Message. The values are QosAtMostOnce, QosAtLeastOnce and QosExactlyOnce.
+// An error is returned if the value is not one of these.
+func (this *PublishMessage) SetQoS(v byte) error {
+	if v != 0x0 && v != 0x1 && v != 0x2 {
+		return fmt.Errorf("publish/SetQoS: Invalid QoS %d.", v)
+	}
+
+	this.mtypeflags[0] = (this.mtypeflags[0] & 249) | (v << 1) // 249 = 11111001
+
+	return nil
+}
+
+// Topic returns the the topic name that identifies the information channel to which
+// payload data is published.
+func (this *PublishMessage) Topic() []byte {
+	return this.topic
+}
+
+// SetTopic sets the the topic name that identifies the information channel to which
+// payload data is published. An error is returned if ValidTopic() is falbase.
+func (this *PublishMessage) SetTopic(v []byte) error {
+	if !ValidTopic(v) {
+		return fmt.Errorf("publish/SetTopic: Invalid topic name (%s). Must not be empty or contain wildcard characters", string(v))
+	}
+
+	this.topic = v
+	this.dirty = true
+
+	return nil
+}
+
+// Payload returns the application message that's part of the PUBLISH message.
+func (this *PublishMessage) Payload() []byte {
+	return this.payload
+}
+
+// SetPayload sets the application message that's part of the PUBLISH message.
+func (this *PublishMessage) SetPayload(v []byte) {
+	this.payload = v
+	this.dirty = true
+}
+
+func (this *PublishMessage) 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 *PublishMessage) Decode(src []byte) (int, error) {
+	total := 0
+
+	hn, err := this.header.decode(src[total:])
+	total += hn
+	if err != nil {
+		return total, err
+	}
+
+	n := 0
+
+	this.topic, n, err = readLPBytes(src[total:])
+	total += n
+	if err != nil {
+		return total, err
+	}
+
+	if !ValidTopic(this.topic) {
+		return total, fmt.Errorf("publish/Decode: Invalid topic name (%s). Must not be empty or contain wildcard characters", string(this.topic))
+	}
+
+	// The packet identifier field is only present in the PUBLISH packets where the
+	// QoS level is 1 or 2
+	if this.QoS() != 0 {
+		//this.packetId = binary.BigEndian.Uint16(src[total:])
+		this.packetId = src[total : total+2]
+		total += 2
+	}
+
+	l := int(this.remlen) - (total - hn)
+	this.payload = src[total : total+l]
+	total += len(this.payload)
+
+	this.dirty = false
+
+	return total, nil
+}
+
+func (this *PublishMessage) Encode(dst []byte) (int, error) {
+	if !this.dirty {
+		if len(dst) < len(this.dbuf) {
+			return 0, fmt.Errorf("publish/Encode: Insufficient buffer size. Expecting %d, got %d.", len(this.dbuf), len(dst))
+		}
+
+		return copy(dst, this.dbuf), nil
+	}
+
+	if len(this.topic) == 0 {
+		return 0, fmt.Errorf("publish/Encode: Topic name is empty.")
+	}
+
+	if len(this.payload) == 0 {
+		return 0, fmt.Errorf("publish/Encode: Payload is empty.")
+	}
+
+	ml := this.msglen()
+
+	if err := this.SetRemainingLength(int32(ml)); err != nil {
+		return 0, err
+	}
+
+	hl := this.header.msglen()
+
+	if len(dst) < hl+ml {
+		return 0, fmt.Errorf("publish/Encode: Insufficient buffer size. Expecting %d, got %d.", hl+ml, len(dst))
+	}
+
+	total := 0
+
+	n, err := this.header.encode(dst[total:])
+	total += n
+	if err != nil {
+		return total, err
+	}
+
+	n, err = writeLPBytes(dst[total:], this.topic)
+	total += n
+	if err != nil {
+		return total, err
+	}
+
+	// The packet identifier field is only present in the PUBLISH packets where the QoS level is 1 or 2
+	if this.QoS() != 0 {
+		if this.PacketId() == 0 {
+			this.SetPacketId(uint16(atomic.AddUint64(&gPacketId, 1) & 0xffff))
+			//this.packetId = uint16(atomic.AddUint64(&gPacketId, 1) & 0xffff)
+		}
+
+		n = copy(dst[total:], this.packetId)
+		//binary.BigEndian.PutUint16(dst[total:], this.packetId)
+		total += n
+	}
+
+	copy(dst[total:], this.payload)
+	total += len(this.payload)
+
+	return total, nil
+}
+
+func (this *PublishMessage) msglen() int {
+	total := 2 + len(this.topic) + len(this.payload)
+	if this.QoS() != 0 {
+		total += 2
+	}
+
+	return total
+}