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/*
* Copyright 2019-present HiveMQ GmbH
*
* 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 com.hivemq.codec.decoder;
import com.hivemq.bootstrap.ClientConnectionContext;
import com.hivemq.configuration.HivemqId;
import com.hivemq.configuration.service.FullConfigurationService;
import com.hivemq.configuration.service.InternalConfigurations;
import com.hivemq.extension.sdk.api.annotations.NotNull;
import com.hivemq.extension.sdk.api.annotations.Nullable;
import com.hivemq.mqtt.handler.connack.MqttConnacker;
import com.hivemq.mqtt.message.QoS;
import com.hivemq.mqtt.message.connect.CONNECT;
import com.hivemq.mqtt.message.connect.MqttWillPublish;
import com.hivemq.mqtt.message.reason.Mqtt5ConnAckReasonCode;
import com.hivemq.util.Bytes;
import com.hivemq.util.ClientIds;
import com.hivemq.util.ReasonStrings;
import com.hivemq.util.Strings;
import io.netty.buffer.ByteBuf;
import static com.hivemq.util.Bytes.isBitSet;
/**
* An Abstract Class for all Mqtt CONNECT Decoders
*
* @author Florian Limpöck
*/
public abstract class AbstractMqttConnectDecoder extends MqttDecoder {
protected static final int DISCONNECTED = -1;
private static final byte VARIABLE_HEADER_LENGTH = 10;
protected final @NotNull MqttConnacker mqttConnacker;
protected final @NotNull ClientIds clientIds;
protected final long maxSessionExpiryInterval;
protected final long maxUserPropertiesLength;
protected final boolean allowAssignedClientId;
protected final boolean validateUTF8;
protected AbstractMqttConnectDecoder(
final @NotNull MqttConnacker mqttConnacker,
final @NotNull FullConfigurationService configurationService,
final @NotNull ClientIds clientIds) {
this.mqttConnacker = mqttConnacker;
this.clientIds = clientIds;
validateUTF8 = configurationService.securityConfiguration().validateUTF8();
maxUserPropertiesLength = InternalConfigurations.USER_PROPERTIES_MAX_SIZE_BYTES;
maxSessionExpiryInterval = configurationService.mqttConfiguration().maxSessionExpiryInterval();
allowAssignedClientId = configurationService.securityConfiguration().allowServerAssignedClientId();
}
protected void disconnectByInvalidFixedHeader(final @NotNull ClientConnectionContext clientConnectionContext) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"A client (IP: {}) connected with an invalid fixed header.",
"Invalid CONNECT fixed header",
Mqtt5ConnAckReasonCode.MALFORMED_PACKET,
ReasonStrings.CONNACK_MALFORMED_PACKET_FIXED_HEADER);
}
protected void disconnectByInvalidHeader(final @NotNull ClientConnectionContext clientConnectionContext) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"A client (ID: {},IP: {}) connected with an invalid CONNECT header.",
"Invalid CONNECT header",
Mqtt5ConnAckReasonCode.PROTOCOL_ERROR,
ReasonStrings.CONNACK_PROTOCOL_ERROR_VARIABLE_HEADER);
}
/**
* Validates Will Flags by MQTT Specification.
*
* If the Will Flag is set to 0, then the Will QoS MUST be set to 0. If the Will Flag is set to 0, then Will Retain
* MUST be set to 0
*
* If the Will Flag is set to 1, the value of Will QoS can be 0, 1, or 2.
*
* A Will QoS of 3 is a malformed packet.
*
* A Will QoS of 0 and a Will Retain of 1 is a malformed packet.
*
* @param isWillFlag will flag set
* @param isWillRetain will retain set
* @param willQoS quality of service of will
* @param clientConnectionContext the connection of the mqtt client
* @return true if valid, else false
*/
protected boolean validateWill(
final boolean isWillFlag,
final boolean isWillRetain,
final int willQoS,
final @NotNull ClientConnectionContext clientConnectionContext) {
final boolean valid = (isWillFlag && willQoS < 3) || (!isWillRetain && willQoS == 0);
if (!valid) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"A client (IP: {}) connected with an invalid willTopic flag combination. Disconnecting client.",
"Invalid will-topic/flag combination",
Mqtt5ConnAckReasonCode.MALFORMED_PACKET,
ReasonStrings.CONNACK_MALFORMED_WILL_FLAG);
}
return valid;
}
/**
* Validates the connect flags byte
*
* If the first bit of the connect flags byte is set, it is a malformed packet
*
* @param connectFlagsByte the connect flags byte
* @param clientConnectionContext the connection of the mqtt client
* @return false if the reserved bit zero is set to 1, else true
*/
protected boolean validateConnectFlagByte(
final byte connectFlagsByte, final @NotNull ClientConnectionContext clientConnectionContext) {
if (isBitSet(connectFlagsByte, 0)) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"A client (IP: {}) connected with invalid CONNECT flags. Disconnecting client.",
"Invalid CONNECT flags",
Mqtt5ConnAckReasonCode.MALFORMED_PACKET,
ReasonStrings.CONNACK_MALFORMED_CONNECT_FLAGS);
return false;
}
return true;
}
/**
* Validates the protocol name of the MQTT Version
*
* If the validation fails it is an unsupported protocol version error.
*
* @param variableHeader the variable header of a mqtt connect message
* @param clientConnectionContext the connection of the mqtt client
* @return true if valid, else false
*/
protected boolean validateProtocolName(
final @NotNull ByteBuf variableHeader,
final @NotNull ClientConnectionContext clientConnectionContext,
final @NotNull String protocolName) {
if (!protocolName.equals(Strings.getPrefixedString(variableHeader))) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"A client (IP: {}) connected with an invalid protocol name. Disconnecting client.",
"Invalid CONNECT protocol name",
Mqtt5ConnAckReasonCode.UNSUPPORTED_PROTOCOL_VERSION,
ReasonStrings.CONNACK_UNSUPPORTED_PROTOCOL_VERSION);
variableHeader.clear();
return false;
}
return true;
}
/**
* THIS IS FOR MQTT 3 ONLY !
*
* checks if the username flag is set when the password flag is set
*/
protected boolean validateUsernamePassword(final boolean isUsernameFlag, final boolean isPasswordFlag) {
//Validates that the username flag is set if the password flag is set
return !isPasswordFlag || isUsernameFlag;
}
/**
* decodes the fixed part of the connect variable header.
*
* the buf reader index will be increased by the length
*
* if readable bytes less than length a connack with protocol error reason code will be sent.
*
* @param clientConnectionContext the connection of the mqtt client
* @param buf the encoded ByteBuf of the message
* @return a new ByteBuf of the fixed variable header part or {@code null} in an error case
*/
protected @Nullable ByteBuf decodeFixedVariableHeaderConnect(
final @NotNull ClientConnectionContext clientConnectionContext, final @NotNull ByteBuf buf) {
if (buf.readableBytes() >= VARIABLE_HEADER_LENGTH) {
return buf.readSlice(VARIABLE_HEADER_LENGTH);
} else {
disconnectByInvalidHeader(clientConnectionContext);
return null;
}
}
/**
* Decodes and validates a Mqtt3 LWT (Will)
*
* Client will be disconnected by:
*
* - Bad will topic length
*
* - topic with bad UTF-8 Character
*
* - topic is empty
*
* - topic contains null character
*
* @param clientConnectionContext the connection of the mqtt client
* @param buf the ByteBuf of the encoded will message
* @param willQoS the quality of service of the will message
* @param isWillRetain the retain flag of the will message
* @param hiveMQId the HiveMQ identifier
* @return a {@link MqttWillPublish} if valid, else {@code null}.
*/
@Nullable
protected MqttWillPublish readMqtt3WillPublish(
final @NotNull ClientConnectionContext clientConnectionContext,
final @NotNull ByteBuf buf,
final int willQoS,
final boolean isWillRetain,
final @NotNull HivemqId hiveMQId) {
final MqttWillPublish.Mqtt3Builder willBuilder = new MqttWillPublish.Mqtt3Builder();
willBuilder.withQos(QoS.valueOf(willQoS));
willBuilder.withRetain(isWillRetain);
final String willTopic;
final int utf8StringLengthWill;
if (buf.readableBytes() < 2 || buf.readableBytes() < (utf8StringLengthWill = buf.readUnsignedShort())) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"A client (IP: {}) sent a CONNECT with an incorrect will-topic length. Disconnecting client.",
"Incorrect CONNECT will-topic length",
Mqtt5ConnAckReasonCode.MALFORMED_PACKET,
ReasonStrings.CONNACK_MALFORMED_PACKET_INCORRECT_WILL_TOPIC_LENGTH);
return null;
}
if (validateUTF8) {
willTopic = Strings.getValidatedPrefixedString(buf, utf8StringLengthWill, true);
if (willTopic == null) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
"The will-topic of the client (IP: {}) is not well formed. This is not allowed. Disconnecting client.",
"Sent CONNECT with bad UTF-8 character",
Mqtt5ConnAckReasonCode.MALFORMED_PACKET,
ReasonStrings.CONNACK_MALFORMED_PACKET_BAD_UTF8);
return null;
}
} else {
willTopic = Strings.getPrefixedString(buf, utf8StringLengthWill);
}
if (isInvalidTopic(clientConnectionContext, willTopic)) {
mqttConnacker.connackError(clientConnectionContext.getChannel(),
null,
//already logged
"Sent CONNECT with invalid will-topic",
Mqtt5ConnAckReasonCode.MALFORMED_PACKET,
ReasonStrings.CONNACK_MALFORMED_PACKET_INVALID_WILL_TOPIC);
return null;
}
final byte[] prefixedBytes = Bytes.getPrefixedBytes(buf);
final byte[] willMessage = prefixedBytes != null ? prefixedBytes : new byte[0];
return willBuilder.withPayload(willMessage).withTopic(willTopic).withHivemqId(hiveMQId.get()).build();
}
}