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mqttpacket.cpp
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/*
This file is part of FlashMQ (https://www.flashmq.org)
Copyright (C) 2021-2023 Wiebe Cazemier
FlashMQ is free software: you can redistribute it and/or modify
it under the terms of The Open Software License 3.0 (OSL-3.0).
See LICENSE for license details.
*/
#include "mqttpacket.h"
#include <cstring>
#include <iostream>
#include <list>
#include <cassert>
#include "utils.h"
#include "threadglobals.h"
#include "subscriptionstore.h"
#include "mainapp.h"
#include "exceptions.h"
#include "acksender.h"
// constructor for parsing incoming packets
MqttPacket::MqttPacket(CirBuf &buf, size_t packet_len, size_t fixed_header_length, std::shared_ptr<Client> &sender) :
bites(packet_len),
fixed_header_length(fixed_header_length),
sender(sender)
{
assert(packet_len > 0);
if (packet_len > sender->getMaxIncomingPacketSize())
{
throw ProtocolError("Incoming packet size exceeded.", ReasonCodes::PacketTooLarge);
}
buf.read(bites.data(), packet_len);
protocolVersion = sender->getProtocolVersion();
first_byte = bites[0];
unsigned char _packetType = (first_byte & 0xF0) >> 4;
packetType = (PacketType)_packetType;
pos += fixed_header_length;
externallyReceived = true;
}
MqttPacket::MqttPacket(const ConnAck &connAck) :
bites(connAck.getLengthWithoutFixedHeader())
{
packetType = PacketType::CONNACK;
first_byte = static_cast<char>(packetType) << 4;
writeByte(connAck.session_present & 0b00000001); // all connect-ack flags are 0, except session-present. [MQTT-3.2.2.1]
writeByte(connAck.return_code);
if (connAck.protocol_version >= ProtocolVersion::Mqtt5)
{
// TODO: don't include the reason string and user properties when it would increase the CONACK packet beyond the max packet size as determined by client.
// We don't send those at all momentarily, so there is no logic to prevent it.
writeProperties(connAck.propertyBuilder);
}
calculateRemainingLength();
}
MqttPacket::MqttPacket(const SubAck &subAck) :
bites(subAck.getLengthWithoutFixedHeader())
{
packetType = PacketType::SUBACK;
first_byte = static_cast<char>(packetType) << 4;
writeUint16(subAck.packet_id);
if (subAck.protocol_version >= ProtocolVersion::Mqtt5)
{
// TODO: don't include the reason string and user properties when it would increase the SUBACK packet beyond the max packet size as determined by client.
// We don't send those at all momentarily, so there is no logic to prevent it.
writeProperties(subAck.propertyBuilder);
}
std::vector<char> returnList;
returnList.reserve(subAck.responses.size());
for (ReasonCodes code : subAck.responses)
{
returnList.push_back(static_cast<char>(code));
}
writeBytes(&returnList[0], returnList.size());
calculateRemainingLength();
}
MqttPacket::MqttPacket(const UnsubAck &unsubAck) :
bites(unsubAck.getLengthWithoutFixedHeader())
{
packetType = PacketType::UNSUBACK;
first_byte = static_cast<char>(packetType) << 4;
writeUint16(unsubAck.packet_id);
if (unsubAck.protocol_version >= ProtocolVersion::Mqtt5)
{
writeProperties(unsubAck.propertyBuilder);
for(const ReasonCodes &rc : unsubAck.reasonCodes)
{
writeByte(static_cast<uint8_t>(rc));
}
}
calculateRemainingLength();
}
size_t MqttPacket::setClientSpecificPropertiesAndGetRequiredSizeForPublish(const ProtocolVersion protocolVersion, Publish &publish) const
{
size_t result = publish.getLengthWithoutFixedHeader();
if (protocolVersion >= ProtocolVersion::Mqtt5)
{
publish.setClientSpecificProperties();
const size_t proplen = publish.propertyBuilder ? publish.propertyBuilder->getLength() : 1;
result += proplen;
}
return result;
}
/**
* @brief Construct a packet for a specific protocol version.
* @param protocolVersion is required here, and not on the Publish object, because publishes don't have a protocol until they are for a specific client.
* @param _publish
*
* Important to note here is that there are two concepts here: writing the byte array for sending to clients, and setting the data in publishData. The latter
* will only have stuff important for internal logic. In other words, it won't contain the payload.
*/
MqttPacket::MqttPacket(const ProtocolVersion protocolVersion, Publish &_publish) :
bites(setClientSpecificPropertiesAndGetRequiredSizeForPublish(protocolVersion, _publish))
{
if (_publish.topic.length() > 0xFFFF)
{
throw ProtocolError("Topic path too long.", ReasonCodes::ProtocolError);
}
this->protocolVersion = protocolVersion;
this->publishData.client_id = _publish.client_id;
this->publishData.username = _publish.username;
if (!_publish.skipTopic)
this->publishData.topic = _publish.topic;
packetType = PacketType::PUBLISH;
this->publishData.qos = _publish.qos;
first_byte = static_cast<char>(packetType) << 4;
first_byte |= (_publish.qos << 1);
first_byte |= (static_cast<char>(_publish.retain) & 0b00000001);
writeString(publishData.topic);
if (publishData.qos)
{
// Reserve the space for the packet id, which will be assigned later.
packet_id_pos = pos;
#ifndef NDEBUG
char zero[2] = {0,0};
writeBytes(zero, 2);
#else
advancePos(2);
#endif
}
if (protocolVersion >= ProtocolVersion::Mqtt5)
{
// Step 1: make certain properties available as objects, because FlashMQ needs access to them for internal logic (only ACL checking at this point).
if (_publish.hasUserProperties())
{
this->publishData.constructPropertyBuilder();
this->publishData.propertyBuilder->setNewUserProperties(_publish.propertyBuilder->getUserProperties());
}
// Step 2: this line will make sure the whole byte array containing all properties as flat bytes is present in the 'bites' vector,
// which is sent to the subscribers.
writeProperties(_publish.propertyBuilder);
// And again, even though the expiry info has been written in the byte array, we need to store them in the publish object too,
// in case we use that, like when queueing QoS packets.
if (_publish.getHasExpireInfo())
{
this->publishData.setExpireAfter(_publish.getExpiresAfter().count());
}
}
payloadStart = pos;
payloadLen = _publish.payload.length();
writeBytes(_publish.payload.c_str(), _publish.payload.length());
calculateRemainingLength();
}
MqttPacket::MqttPacket(const PubResponse &pubAck) :
bites(pubAck.getLengthIncludingFixedHeader())
{
this->protocolVersion = pubAck.protocol_version;
fixed_header_length = 2;
const uint8_t firstByteDefaultBits = pubAck.packet_type == PacketType::PUBREL ? 0b0010 : 0;
this->first_byte = (static_cast<uint8_t>(pubAck.packet_type) << 4) | firstByteDefaultBits;
writeByte(first_byte);
writeByte(pubAck.getRemainingLength());
this->packet_id_pos = this->pos;
writeUint16(pubAck.packet_id);
if (pubAck.needsReasonCode())
{
// TODO: don't include the reason string and user properties when it would increase the PUBACK/PUBREL/PUBCOMP packet beyond the max packet size as determined by client.
// We don't send those at all momentarily, so there is no logic to prevent it.
writeByte(static_cast<uint8_t>(pubAck.reason_code));
}
}
/**
* @brief Constructor to create a disconnect packet. In normal server mode, only MQTT5 is supposed to do that (MQTT3 has no concept of server-initiated
* disconnect packet). But, we also use it in the test client.
* @param disconnect
*/
MqttPacket::MqttPacket(const Disconnect &disconnect) :
bites(disconnect.getLengthWithoutFixedHeader())
{
this->protocolVersion = disconnect.protocolVersion;
packetType = PacketType::DISCONNECT;
first_byte = static_cast<char>(packetType) << 4;
if (this->protocolVersion >= ProtocolVersion::Mqtt5)
{
writeByte(static_cast<uint8_t>(disconnect.reasonCode));
writeProperties(disconnect.propertyBuilder);
}
calculateRemainingLength();
}
MqttPacket::MqttPacket(const Auth &auth) :
bites(auth.getLengthWithoutFixedHeader()),
protocolVersion(ProtocolVersion::Mqtt5),
packetType(PacketType::AUTH)
{
first_byte = static_cast<char>(packetType) << 4;
writeByte(static_cast<uint8_t>(auth.reasonCode));
writeProperties(auth.propertyBuilder);
calculateRemainingLength();
}
MqttPacket::MqttPacket(const Connect &connect) :
bites(connect.getLengthWithoutFixedHeader()),
protocolVersion(connect.protocolVersion),
packetType(PacketType::CONNECT)
{
first_byte = static_cast<char>(packetType) << 4;
const std::string_view magicString = connect.getMagicString();
writeString(magicString);
uint8_t protocolVersionByte = static_cast<uint8_t>(protocolVersion);
if (connect.bridgeProtocolBit && protocolVersion <= ProtocolVersion::Mqtt311) // MQTT5 uses subscription options for it.
protocolVersionByte |= 0x80;
writeByte(protocolVersionByte);
uint8_t flags = connect.clean_start << 1;
flags |= !connect.username.empty() << 7;
flags |= !connect.password.empty() << 6;
if (connect.will)
{
flags |= 4;
flags |= (connect.will->qos << 3);
flags |= (connect.will->retain << 5);
}
writeByte(flags);
writeUint16(connect.keepalive);
if (connect.protocolVersion >= ProtocolVersion::Mqtt5)
{
writeProperties(connect.propertyBuilder);
}
writeString(connect.clientid);
if (connect.will)
{
if (connect.protocolVersion >= ProtocolVersion::Mqtt5)
{
writeProperties(connect.will->propertyBuilder);
}
writeString(connect.will->topic);
writeString(connect.will->payload);
}
if (!connect.username.empty())
writeString(connect.username);
if (!connect.password.empty())
writeString(connect.password);
calculateRemainingLength();
}
MqttPacket::MqttPacket(const Subscribe &subscribe) :
bites(subscribe.getLengthWithoutFixedHeader()),
packetType(PacketType::SUBSCRIBE)
{
first_byte = static_cast<char>(packetType) << 4;
first_byte |= 2; // required reserved bit
writeUint16(subscribe.packetId);
if (subscribe.protocolVersion >= ProtocolVersion::Mqtt5)
{
writeProperties(subscribe.propertyBuilder);
}
writeString(subscribe.topic);
if (subscribe.protocolVersion < ProtocolVersion::Mqtt5)
{
writeByte(subscribe.qos);
}
else
{
SubscriptionOptionsByte options(subscribe.qos, subscribe.noLocal, subscribe.retainAsPublished);
writeByte(options.b);
}
calculateRemainingLength();
}
MqttPacket::MqttPacket(const Unsubscribe &unsubscribe) :
bites(unsubscribe.getLengthWithoutFixedHeader()),
packetType(PacketType::UNSUBSCRIBE)
{
#ifndef TESTING
throw NotImplementedException("Code is only for testing.");
#endif
first_byte = static_cast<char>(packetType) << 4;
first_byte |= 2; // required reserved bit
writeUint16(unsubscribe.packetId);
if (unsubscribe.protocolVersion >= ProtocolVersion::Mqtt5)
{
writeProperties(unsubscribe.propertyBuilder);
}
writeString(unsubscribe.topic);
calculateRemainingLength();
}
void MqttPacket::bufferToMqttPackets(CirBuf &buf, std::vector<MqttPacket> &packetQueueIn, std::shared_ptr<Client> &sender)
{
while (buf.usedBytes() >= MQTT_HEADER_LENGH)
{
// Determine the packet length by decoding the variable length
int remaining_length_i = 1; // index of 'remaining length' field is one after start.
uint fixed_header_length = 1;
size_t multiplier = 1;
size_t packet_length = 0;
unsigned char encodedByte = 0;
do
{
fixed_header_length++;
if (fixed_header_length > 5)
throw ProtocolError("Packet signifies more than 5 bytes in variable length header. Invalid.", ReasonCodes::MalformedPacket);
// This happens when you only don't have all the bytes that specify the remaining length.
if (fixed_header_length > buf.usedBytes())
return;
encodedByte = buf.peakAhead(remaining_length_i++);
packet_length += (encodedByte & 127) * multiplier;
multiplier *= 128;
if (multiplier > 128*128*128*128)
throw ProtocolError("Malformed Remaining Length.", ReasonCodes::MalformedPacket);
}
while ((encodedByte & 128) != 0);
packet_length += fixed_header_length;
if (sender && !sender->getAuthenticated() && packet_length >= 1024*1024)
{
throw ProtocolError("An unauthenticated client sends a packet of 1 MB or bigger? Probably it's just random bytes.", ReasonCodes::ProtocolError);
}
const uint32_t size_limit = std::min<uint32_t>(sender->getMaxIncomingPacketSize(), ABSOLUTE_MAX_PACKET_SIZE);
if (packet_length > size_limit)
{
std::ostringstream oss;
oss << "Packet size " << packet_length << " exceeds the server limit of " << size_limit << " bytes";
throw ProtocolError(oss.str(), ReasonCodes::PacketTooLarge);
}
if (packet_length <= buf.usedBytes())
{
packetQueueIn.emplace_back(buf, packet_length, fixed_header_length, sender);
}
else
break;
}
}
void MqttPacket::handle()
{
// For clients that send packets before they even receive a connack.
if (protocolVersion == ProtocolVersion::None)
protocolVersion = sender->getProtocolVersion();
// It may be a stale client. This is especially important for when a session is picked up by another client. The old client
// may still have stale data in the buffer, causing action on the session otherwise.
if (sender->isBeingDisconnected())
return;
if (packetType == PacketType::Reserved)
throw ProtocolError("Packet type 0 specified, which is reserved and invalid.", ReasonCodes::MalformedPacket);
if (!sender->getAuthenticated())
{
if (packetType == PacketType::AUTH && sender->getExtendedAuthenticationMethod().empty())
{
throw ProtocolError("You can't initiate first (extended) authentication with an AUTH packet.", ReasonCodes::ProtocolError);
}
if (!(packetType == PacketType::CONNECT || packetType == PacketType::AUTH || packetType == PacketType::DISCONNECT ||
packetType == PacketType::PINGREQ || packetType == PacketType::PINGRESP || packetType == PacketType::CONNACK))
{
exceptionOnNonMqtt(this->bites);
logger->log(LOG_WARNING) << "Unapproved packet type (code " << static_cast<int>(packetType)
<< ") from non-authenticated client " << sender->repr() << ". Dropping packet.";
return;
}
}
if (packetType == PacketType::PUBLISH)
handlePublish();
else if (packetType == PacketType::PUBACK)
handlePubAck();
else if (packetType == PacketType::PUBREC)
handlePubRec();
else if (packetType == PacketType::PUBREL)
handlePubRel();
else if (packetType == PacketType::PUBCOMP)
handlePubComp();
else if (packetType == PacketType::PINGREQ)
sender->writePingResp();
else if (packetType == PacketType::SUBSCRIBE)
handleSubscribe();
else if (packetType == PacketType::UNSUBSCRIBE)
handleUnsubscribe();
else if (packetType == PacketType::SUBACK)
handleSubAck();
else if (packetType == PacketType::CONNECT)
handleConnect();
else if (packetType == PacketType::DISCONNECT)
handleDisconnect();
else if (packetType == PacketType::CONNACK)
handleConnAck();
else if (packetType == PacketType::AUTH)
handleExtendedAuth();
}
ConnectData MqttPacket::parseConnectData()
{
if (this->packetType != PacketType::CONNECT)
throw std::runtime_error("Packet must be connect packet.");
setPosToDataStart();
ConnectData result;
uint16_t variable_header_length = readTwoBytesToUInt16();
if (!(variable_header_length == 4 || variable_header_length == 6))
{
throw ProtocolError("Invalid variable header length. Garbage?", ReasonCodes::MalformedPacket);
}
const Settings &settings = *ThreadGlobals::getSettings();
const char *c = readBytes(variable_header_length);
const std::string magic_marker(c, variable_header_length);
const uint8_t protocolVersionByte = readUint8();
result.protocol_level_byte = protocolVersionByte & 0x7F;
result.bridge = protocolVersionByte & 0x80; // Unofficial, defacto, way of specifying that. MQTT5 uses subscription options for it.
if (magic_marker == "MQTT")
{
if (result.protocol_level_byte == 0x04)
protocolVersion = ProtocolVersion::Mqtt311;
if (result.protocol_level_byte == 0x05)
protocolVersion = ProtocolVersion::Mqtt5;
}
else if (magic_marker == "MQIsdp" && result.protocol_level_byte == 0x03)
{
protocolVersion = ProtocolVersion::Mqtt31;
}
else
{
throw ProtocolError("Packet contains invalid MQTT marker.", ReasonCodes::MalformedPacket);
}
// Even though we're still parsing, setting this helps the exception handler to make decisions.
sender->setProtocolVersion(this->protocolVersion);
char flagByte = readByte();
bool reserved = !!(flagByte & 0b00000001);
if (reserved)
throw ProtocolError("Protocol demands reserved flag in CONNECT is 0", ReasonCodes::MalformedPacket);
bool user_name_flag = static_cast<bool>(flagByte & 0b10000000);
result.password_flag = !!(flagByte & 0b01000000);
result.will_retain = !!(flagByte & 0b00100000);
result.will_qos = (flagByte & 0b00011000) >> 3;
result.will_flag = !!(flagByte & 0b00000100);
result.clean_start = !!(flagByte & 0b00000010);
if (result.will_qos > 2)
throw ProtocolError("Invalid QoS for will.", ReasonCodes::MalformedPacket);
result.keep_alive = readTwoBytesToUInt16();
if (protocolVersion == ProtocolVersion::Mqtt5)
{
result.keep_alive = std::max<uint16_t>(result.keep_alive, 5);
const size_t proplen = decodeVariableByteIntAtPos();
const size_t prop_end_at = pos + proplen;
while (pos < prop_end_at)
{
const Mqtt5Properties prop = static_cast<Mqtt5Properties>(readUint8());
switch (prop)
{
case Mqtt5Properties::SessionExpiryInterval:
result.session_expire = std::min<uint32_t>(readFourBytesToUint32(), result.session_expire);
break;
case Mqtt5Properties::ReceiveMaximum:
result.client_receive_max = std::min<int16_t>(readTwoBytesToUInt16(), result.client_receive_max);
break;
case Mqtt5Properties::MaximumPacketSize:
result.max_outgoing_packet_size = std::min<uint32_t>(readFourBytesToUint32(), result.max_outgoing_packet_size);
break;
case Mqtt5Properties::TopicAliasMaximum:
result.max_outgoing_topic_aliases = std::min<uint16_t>(readTwoBytesToUInt16(), settings.maxOutgoingTopicAliasValue);
break;
case Mqtt5Properties::RequestResponseInformation:
result.request_response_information = !!readByte();
break;
case Mqtt5Properties::RequestProblemInformation:
result.request_problem_information = !!readByte();
break;
case Mqtt5Properties::UserProperty:
readUserProperty();
break;
case Mqtt5Properties::AuthenticationMethod:
{
result.authenticationMethod = readBytesToString();
break;
}
case Mqtt5Properties::AuthenticationData:
{
result.authenticationData = readBytesToString(false);
break;
}
default:
throw ProtocolError("Invalid connect property.", ReasonCodes::ProtocolError);
}
}
}
if (result.client_receive_max == 0 || result.max_outgoing_packet_size == 0)
{
throw ProtocolError("Receive max or max outgoing packet size can't be 0.", ReasonCodes::ProtocolError);
}
result.client_id = readBytesToString();
if (result.will_flag)
{
result.willpublish.qos = result.will_qos;
result.willpublish.retain = result.will_retain;
if (result.will_retain)
{
if (settings.retainedMessagesMode == RetainedMessagesMode::DisconnectWithError)
throw ProtocolError("Option 'retained_messages_mode' set to 'disconnect_with_error' and received a will with retain.", ReasonCodes::RetainNotSupported);
else if (settings.retainedMessagesMode == RetainedMessagesMode::Downgrade)
{
result.willpublish.retain = false;
result.will_retain = false;
}
else if (settings.retainedMessagesMode == RetainedMessagesMode::Drop)
result.will_flag = false; // This will make us not pick up later, and we still parse the bytes from the packet.
}
result.willpublish.client_id = result.client_id;
if (protocolVersion == ProtocolVersion::Mqtt5)
{
result.willpublish.constructPropertyBuilder();
const size_t proplen = decodeVariableByteIntAtPos();
const size_t prop_end_at = pos + proplen;
while (pos < prop_end_at)
{
const Mqtt5Properties prop = static_cast<Mqtt5Properties>(readUint8());
switch (prop)
{
case Mqtt5Properties::WillDelayInterval:
result.willpublish.will_delay = readFourBytesToUint32();
break;
case Mqtt5Properties::PayloadFormatIndicator:
result.willpublish.propertyBuilder->writePayloadFormatIndicator(readByte());
break;
case Mqtt5Properties::ContentType:
{
const std::string contentType = readBytesToString();
result.willpublish.propertyBuilder->writeContentType(contentType);
break;
}
case Mqtt5Properties::ResponseTopic:
{
const std::string responseTopic = readBytesToString(true, true);
result.willpublish.propertyBuilder->writeResponseTopic(responseTopic);
break;
}
case Mqtt5Properties::MessageExpiryInterval:
{
const uint32_t expiresAfter = readFourBytesToUint32();
result.willpublish.setExpireAfter(expiresAfter);
break;
}
case Mqtt5Properties::CorrelationData:
{
const std::string correlationData = readBytesToString(false);
result.willpublish.propertyBuilder->writeCorrelationData(correlationData);
break;
}
case Mqtt5Properties::UserProperty:
{
result.willpublish.constructPropertyBuilder();
std::string key = readBytesToString();
std::string value = readBytesToString();
result.willpublish.propertyBuilder->writeUserProperty(std::move(key), std::move(value));
break;
}
default:
throw ProtocolError("Invalid will property in connect.", ReasonCodes::ProtocolError);
}
}
}
result.willpublish.topic = readBytesToString(true, true);
uint16_t will_payload_length = readTwoBytesToUInt16();
result.willpublish.payload = std::string(readBytes(will_payload_length), will_payload_length);
}
if (user_name_flag)
{
result.username = readBytesToString(false);
result.willpublish.username = result.username.value();
if (result.username.value().empty())
throw ProtocolError("Username flagged as present, but it's 0 bytes.", ReasonCodes::MalformedPacket);
if (!settings.allowUnsafeUsernameChars && containsDangerousCharacters(result.username.value()))
throw ProtocolError(formatString("Username '%s' contains unsafe characters and 'allow_unsafe_username_chars' is false.", result.username.value().c_str()),
ReasonCodes::BadUserNameOrPassword);
}
if (result.password_flag)
{
if (this->protocolVersion <= ProtocolVersion::Mqtt311 && !result.username)
{
throw ProtocolError("MQTT 3.1.1: If the User Name Flag is set to 0, the Password Flag MUST be set to 0.", ReasonCodes::MalformedPacket);
}
result.password = readBytesToString(false);
if (result.password.empty())
throw ProtocolError("Password flagged as present, but it's 0 bytes.", ReasonCodes::MalformedPacket);
}
return result;
}
ConnAckData MqttPacket::parseConnAckData()
{
if (this->packetType != PacketType::CONNACK)
throw std::runtime_error("Packet must be connack packet.");
const Settings &settings = *ThreadGlobals::getSettings();
setPosToDataStart();
ConnAckData result;
const uint8_t flagByte = readByte();
result.sessionPresent = flagByte & 0x01;
result.reasonCode = static_cast<ReasonCodes>(readUint8());
if (protocolVersion == ProtocolVersion::Mqtt5)
{
const size_t proplen = decodeVariableByteIntAtPos();
const size_t prop_end_at = pos + proplen;
while (pos < prop_end_at)
{
const Mqtt5Properties prop = static_cast<Mqtt5Properties>(readUint8());
switch (prop)
{
case Mqtt5Properties::SessionExpiryInterval:
result.session_expire = std::min<uint32_t>(readFourBytesToUint32(), result.session_expire);
break;
case Mqtt5Properties::ReceiveMaximum:
result.client_receive_max = std::min<int16_t>(readTwoBytesToUInt16(), result.client_receive_max);
break;
case Mqtt5Properties::MaximumQoS:
result.max_qos = std::min<uint8_t>(readUint8(), result.max_qos);
break;
case Mqtt5Properties::RetainAvailable:
result.retained_available = static_cast<bool>(readByte());
break;
case Mqtt5Properties::MaximumPacketSize:
result.max_outgoing_packet_size = std::min<uint32_t>(readFourBytesToUint32(), result.max_outgoing_packet_size);
break;
case Mqtt5Properties::AssignedClientIdentifier:
result.assigned_client_id = readBytesToString();
break;
case Mqtt5Properties::TopicAliasMaximum:
result.max_outgoing_topic_aliases = std::min<uint16_t>(readTwoBytesToUInt16(), settings.maxOutgoingTopicAliasValue);
break;
case Mqtt5Properties::ReasonString:
{
const std::string reason = readBytesToString();
logger->logf(LOG_INFO, "ConnAck reason string: %s", reason.c_str());
break;
}
case Mqtt5Properties::UserProperty:
{
std::string key = readBytesToString();
std::string value = readBytesToString();
break;
}
case Mqtt5Properties::WildcardSubscriptionAvailable:
readByte();
break;
case Mqtt5Properties::SubscriptionIdentifierAvailable:
readByte();
break;
case Mqtt5Properties::SharedSubscriptionAvailable:
result.shared_subscriptions_available = !!readByte();
break;
case Mqtt5Properties::ServerKeepAlive:
result.keep_alive = readTwoBytesToUInt16();
break;
case Mqtt5Properties::ResponseInformation:
result.response_information = readBytesToString();
break;
case Mqtt5Properties::ServerReference:
result.server_reference = readBytesToString();
break;
case Mqtt5Properties::AuthenticationMethod:
result.authMethod = readBytesToString();
break;
case Mqtt5Properties::AuthenticationData:
result.authData = readBytesToString();
break;
default:
throw ProtocolError("Invalid connack property.", ReasonCodes::ProtocolError);
}
}
}
return result;
}
void MqttPacket::handleConnect()
{
if (sender->hasConnectPacketSeen())
throw ProtocolError("Client already sent a CONNECT.", ReasonCodes::ProtocolError);
std::shared_ptr<SubscriptionStore> subscriptionStore = MainApp::getMainApp()->getSubscriptionStore();
Authentication &authentication = *ThreadGlobals::getAuth();
ThreadData *threadData = ThreadGlobals::getThreadData();
threadData->mqttConnectCounter.inc();
ConnectData connectData = parseConnectData();
sender->setHasConnectPacketSeen();
sender->setProtocolVersion(this->protocolVersion);
sender->setBridge(connectData.bridge);
if (this->protocolVersion == ProtocolVersion::None)
{
if (this->protocolVersion == ProtocolVersion::None)
logger->logf(LOG_ERR, "Rejecting because of invalid protocol version: %s", sender->repr().c_str());
// The specs are unclear when to use the version 3 codes or version 5 codes when you don't know which protocol version to speak.
ProtocolVersion fuzzyProtocolVersion = connectData.protocol_level_byte < 0x05 ? ProtocolVersion::Mqtt31 : ProtocolVersion::Mqtt5;
ConnAck connAck(fuzzyProtocolVersion, ReasonCodes::UnsupportedProtocolVersion);
MqttPacket response(connAck);
sender->setReadyForDisconnect();
sender->writeMqttPacket(response);
sender->setDisconnectReason("Unsupported protocol version");
return;
}
const Settings &settings = *ThreadGlobals::getSettings();
// I deferred the initial UTF8 check on username to be able to give an appropriate connack here, but to me, the specs
// are actually vague whether 'BadUserNameOrPassword' should be given on invalid UTF8.
if (connectData.username && !isValidUtf8(connectData.username.value()))
{
ConnAck connAck(protocolVersion, ReasonCodes::BadUserNameOrPassword);
MqttPacket response(connAck);
sender->setReadyForDisconnect();
sender->writeMqttPacket(response);
logger->logf(LOG_ERR, "Username has invalid UTF8: %s", connectData.username.value().c_str());
return;
}
bool validClientId = true;
// Check for wildcard chars in case the client_id ever appears in topics.
if (!settings.allowUnsafeClientidChars && containsDangerousCharacters(connectData.client_id))
{
logger->logf(LOG_ERR, "ClientID '%s' has + or # in the id and 'allow_unsafe_clientid_chars' is false.", connectData.client_id.c_str());
validClientId = false;
}
else if (protocolVersion < ProtocolVersion::Mqtt5 && !connectData.clean_start && connectData.client_id.empty())
{
logger->logf(LOG_ERR, "ClientID empty and clean start 0, which is incompatible below MQTTv5.");
validClientId = false;
}
else if (protocolVersion < ProtocolVersion::Mqtt311 && connectData.client_id.empty())
{
logger->logf(LOG_ERR, "Empty clientID. Connect with protocol 3.1.1 or higher to have one generated securely.");
validClientId = false;
}
if (!validClientId)
{
ConnAck connAck(protocolVersion, ReasonCodes::ClientIdentifierNotValid);
MqttPacket response(connAck);
sender->setDisconnectReason("Invalid clientID");
sender->setReadyForDisconnect();
sender->writeMqttPacket(response);
return;
}
bool clientIdGenerated = false;
if (connectData.client_id.empty())
{
connectData.client_id = getSecureRandomString(23);
clientIdGenerated = true;
}
sender->setClientId(connectData.client_id);
std::string username = connectData.username ? connectData.username.value() : "";
if (sender->getX509ClientVerification() > X509ClientVerification::None)
{
std::optional<std::string> certificateUsername = sender->getUsernameFromPeerCertificate();
if (!certificateUsername || certificateUsername.value().empty())
throw ProtocolError("Client certificate did not provider username", ReasonCodes::BadUserNameOrPassword);
username = certificateUsername.value();
}
sender->setClientProperties(protocolVersion, connectData.client_id, username, true, connectData.keep_alive,
connectData.max_outgoing_packet_size, connectData.max_outgoing_topic_aliases);
if (settings.willsEnabled && connectData.will_flag)
{
sender->stageWill(std::move(connectData.willpublish));
}
// Stage connack, for immediate or delayed use when auth succeeds.
{
bool sessionPresent = false;
std::shared_ptr<Session> existingSession;
if (protocolVersion >= ProtocolVersion::Mqtt311 && !connectData.clean_start)
{
existingSession = subscriptionStore->lockSession(connectData.client_id);
if (existingSession && !existingSession->getDestroyOnDisconnect())
sessionPresent = true;
}
std::unique_ptr<ConnAck> connAck = std::make_unique<ConnAck>(protocolVersion, ReasonCodes::Success, sessionPresent);
if (protocolVersion >= ProtocolVersion::Mqtt5)
{
connAck->propertyBuilder = std::make_shared<Mqtt5PropertyBuilder>();
connAck->propertyBuilder->writeSessionExpiry(connectData.session_expire);
connAck->propertyBuilder->writeReceiveMax(settings.maxQosMsgPendingPerClient);
connAck->propertyBuilder->writeRetainAvailable(settings.retainedMessagesMode == RetainedMessagesMode::Enabled);
connAck->propertyBuilder->writeMaxPacketSize(sender->getMaxIncomingPacketSize());
if (clientIdGenerated)
connAck->propertyBuilder->writeAssignedClientId(connectData.client_id);
connAck->propertyBuilder->writeMaxTopicAliases(sender->getMaxIncomingTopicAliasValue());
connAck->propertyBuilder->writeWildcardSubscriptionAvailable(1);
connAck->propertyBuilder->writeSubscriptionIdentifiersAvailable(0);
connAck->propertyBuilder->writeSharedSubscriptionAvailable(1);
connAck->propertyBuilder->writeServerKeepAlive(connectData.keep_alive);
if (!connectData.authenticationMethod.empty())
{
connAck->propertyBuilder->writeAuthenticationMethod(connectData.authenticationMethod);
}
}
sender->stageConnack(std::move(connAck));
}
sender->setRegistrationData(connectData.clean_start, connectData.client_receive_max, connectData.session_expire);
AuthResult authResult = AuthResult::login_denied;
std::string authReturnData;
if (!connectData.username && connectData.authenticationMethod.empty() && settings.allowAnonymous)
{
authResult = AuthResult::success;
}
else if (sender->getX509ClientVerification() == X509ClientVerification::X509IsEnough)
{
// The client will have been kicked out already if the certificate is not valid, so we can just approve it.
authResult = AuthResult::success;
}
else if (connectData.authenticationMethod.empty())
{
authResult = authentication.unPwdCheck(connectData.client_id, username, connectData.password, getUserProperties(), sender);
}
else
{
sender->setExtendedAuthenticationMethod(connectData.authenticationMethod);
authResult = authentication.extendedAuth(connectData.client_id, ExtendedAuthStage::Auth, connectData.authenticationMethod, connectData.authenticationData,
getUserProperties(), authReturnData, sender->getMutableUsername(), sender);
}
if (authResult != AuthResult::async)
{
threadData->continuationOfAuthentication(sender, authResult, connectData.authenticationMethod, authReturnData);
}
}
void MqttPacket::handleConnAck()
{
if (!sender->isOutgoingConnection())
return;
if (sender->hasConnectPacketSeen())
throw ProtocolError("Client already sent a CONNACK.", ReasonCodes::ProtocolError);
const Settings *settings = ThreadGlobals::getSettings();
const ConnAckData data = parseConnAckData();
if (data.reasonCode != ReasonCodes::Success)
{
throw std::runtime_error(formatString("Client '%s' connection failed. Reason code: %d", sender->repr().c_str(), data.reasonCode));
}
if (!settings->allowUnsafeClientidChars && containsDangerousCharacters(data.assigned_client_id))
{
const std::string error = formatString("Assigned clientID '%s' has + or # in the id and 'allow_unsafe_clientid_chars' is false.", data.assigned_client_id.c_str());
throw ProtocolError(error, ReasonCodes::ImplementationSpecificError);
}
sender->setAuthenticated(true);
std::shared_ptr<BridgeState> bridgeState = sender->getBridgeState();
// Should be impossible.