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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)
{
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();
}
MqttPacket::MqttPacket(const ProtocolVersion protocolVersion, const Publish &_publish) :
MqttPacket(protocolVersion, _publish, _publish.qos, _publish.topicAlias, _publish.skipTopic, _publish.subscriptionIdentifier)
{
}
/**
* @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.
*
* The extra parameters are for overriding certain properties of the publish, because the receiving client wants it differently. Use the other overload
* if you just want the publish object's data.
*/
MqttPacket::MqttPacket(const ProtocolVersion protocolVersion, const Publish &_publish, const uint8_t _qos, const uint16_t _topic_alias,
const bool _skip_topic, const uint32_t subscriptionIdentifier)
{
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;
this->publishData.skipTopic = _skip_topic;
this->publishData.qos = _qos;
this->publishData.retain = _publish.retain;
this->publishData.topicAlias = _topic_alias;
this->packetType = PacketType::PUBLISH;
if (!this->publishData.skipTopic)
this->publishData.topic = _publish.topic;
first_byte = static_cast<char>(packetType) << 4;
first_byte |= (this->publishData.qos << 1);
first_byte |= (static_cast<char>(publishData.retain) & 0b00000001);
std::optional<Mqtt5PropertyBuilder> property_builder;
if (protocolVersion >= ProtocolVersion::Mqtt5)
{
if (_publish.expireInfo)
this->publishData.setExpireAfter(_publish.expireInfo->getCurrentTimeToExpire().count());
this->publishData.correlationData = _publish.correlationData;
this->publishData.responseTopic = _publish.responseTopic;
this->publishData.contentType = _publish.contentType;
this->publishData.payloadUtf8 = _publish.payloadUtf8;
this->publishData.userProperties = _publish.userProperties;
this->publishData.subscriptionIdentifier = subscriptionIdentifier;
property_builder = this->publishData.getPropertyBuilder();
}
size_t len = 0;
// Calculate length
{
len += 2; // topic string length field
if (!this->publishData.skipTopic)
len += this->publishData.topic.length();
len += _publish.payload.length();
if (this->publishData.qos)
len += 2;
if (protocolVersion >= ProtocolVersion::Mqtt5)
len += property_builder ? property_builder->getLength() : 1;
}
bites.resize(len);
writeString(publishData.topic);
if (publishData.qos)
{
// Reserve the space for the packet id, which will be assigned later.
packet_id_pos = pos;
char zero[2] = {0,0};
writeBytes(zero, 2);
}
if (protocolVersion >= ProtocolVersion::Mqtt5)
writeProperties(property_builder);
payloadStart = pos;
payloadLen = _publish.payload.length();
writeBytes(_publish.payload.c_str(), _publish.payload.length());
calculateRemainingLength();
assert(pos == bites.size());
}
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) :
protocolVersion(connect.protocolVersion),
packetType(PacketType::CONNECT)
{
first_byte = static_cast<char>(packetType) << 4;
const std::string_view magicString = connect.getMagicString();
std::optional<Mqtt5PropertyBuilder> properties;
// If absent, the other side has to assume 0.
if (connect.sessionExpiryInterval)
non_optional(properties)->writeSessionExpiry(connect.sessionExpiryInterval);
// We tell the other side they can send us topics with aliases, if set.
if (connect.maxIncomingTopicAliasValue)
non_optional(properties)->writeMaxTopicAliases(connect.maxIncomingTopicAliasValue);
if (connect.authenticationMethod)
non_optional(properties)->writeAuthenticationMethod(connect.authenticationMethod.value());
if (connect.authenticationData)
non_optional(properties)->writeAuthenticationData(connect.authenticationData.value());
std::optional<Mqtt5PropertyBuilder> will_properties;
if (connect.will && this->protocolVersion >= ProtocolVersion::Mqtt5)
will_properties = connect.will->getPropertyBuilder();
size_t len = 0;
// Calculate length
{
len += connect.clientid.length() + 2;
len += magicString.length();
len += 6; // header stuff, lengths, keep-alive
if (this->protocolVersion >= ProtocolVersion::Mqtt5)
len += properties ? properties->getLength() : 1;
if (connect.will)
{
if (this->protocolVersion >= ProtocolVersion::Mqtt5)
len += will_properties ? will_properties->getLength() : 1;
len += connect.will->topic.length() + 2;
len += connect.will->payload.length() + 2;
}
if (connect.username.has_value())
len += connect.username->size() + 2;
if (connect.password.has_value())
len += connect.password->size() + 2;
}
bites.resize(len);
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 |= static_cast<unsigned int>(connect.username.has_value()) << 7;
flags |= static_cast<unsigned int>(connect.password.has_value()) << 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(properties);
}
writeString(connect.clientid);
if (connect.will)
{
if (connect.protocolVersion >= ProtocolVersion::Mqtt5)
{
writeProperties(will_properties);
}
writeString(connect.will->topic);
writeString(connect.will->payload);
}
if (connect.username.has_value())
writeString(connect.username.value());
if (connect.password.has_value())
writeString(connect.password.value());
calculateRemainingLength();
assert(pos == bites.size());
}
MqttPacket::MqttPacket(const Subscribe &subscribe) :
protocolVersion(subscribe.protocolVersion),
packetType(PacketType::SUBSCRIBE)
{
first_byte = static_cast<char>(packetType) << 4;
first_byte |= 2; // required reserved bit
std::optional<Mqtt5PropertyBuilder> properties;
if (subscribe.protocolVersion >= ProtocolVersion::Mqtt5)
{
if (subscribe.subscriptionIdentifier > 0)
non_optional(properties)->writeSubscriptionIdentifier(subscribe.subscriptionIdentifier);
}
size_t len = 0;
// Calculate length
{
len += subscribe.topic.size() + 2;
len += 2; // packet id
len += 1; // requested QoS
if (subscribe.protocolVersion >= ProtocolVersion::Mqtt5)
len += properties ? properties->getLength() : 1;
}
bites.resize(len);
writeUint16(subscribe.packetId);
if (subscribe.protocolVersion >= ProtocolVersion::Mqtt5)
{
writeProperties(properties);
}
writeString(subscribe.topic);
if (subscribe.protocolVersion < ProtocolVersion::Mqtt5)
{
writeByte(subscribe.qos);
}
else
{
SubscriptionOptionsByte options(subscribe.qos, subscribe.noLocal, subscribe.retainAsPublished, subscribe.retainHandling);
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;
}
}
HandleResult MqttPacket::handle(std::shared_ptr<Client> &sender)
{
// 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->getDisconnectStage() > DisconnectStage::NotInitiated)
return HandleResult::Done;
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::CONNACK))
{
if (sender->getAsyncAuthenticating())
return HandleResult::Defer;
exceptionOnNonMqtt(this->bites);
if (sender->preAuthPacketCounter++ > 200)
throw ProtocolError("Too many pre-auth packets dropped", ReasonCodes::ProtocolError);
logger->log(LOG_WARNING) << "Unapproved packet type (" << packetTypeToString(packetType)
<< ") from non-authenticated client " << sender->repr() << ". Dropping packet.";
return HandleResult::Done;
}
}
if (packetType == PacketType::PUBLISH)
handlePublish(sender);
else if (packetType == PacketType::PUBACK)
handlePubAck(sender);
else if (packetType == PacketType::PUBREC)
handlePubRec(sender);
else if (packetType == PacketType::PUBREL)
handlePubRel(sender);
else if (packetType == PacketType::PUBCOMP)
handlePubComp(sender);
else if (packetType == PacketType::PINGREQ)
sender->writePingResp();
else if (packetType == PacketType::SUBSCRIBE)
handleSubscribe(sender);
else if (packetType == PacketType::UNSUBSCRIBE)
handleUnsubscribe(sender);
else if (packetType == PacketType::SUBACK)
handleSubAck(sender);
else if (packetType == PacketType::CONNECT)
handleConnect(sender);
else if (packetType == PacketType::DISCONNECT)
handleDisconnect(sender);
else if (packetType == PacketType::CONNACK)
handleConnAck(sender);
else if (packetType == PacketType::AUTH)
handleExtendedAuth(sender);
return HandleResult::Done;
}
ConnectData MqttPacket::parseConnectData(std::shared_ptr<Client> &sender)
{
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)
{
/*
* MQTT5: "If the Session Expiry Interval is absent the value 0 is used. If it is set to 0, or is absent,
* the Session ends when the Network Connection is closed."
*/
result.session_expire = 0;
result.keep_alive = std::max<uint16_t>(result.keep_alive, 5);
const size_t proplen = decodeVariableByteIntAtPos();
const size_t prop_end_at = pos + proplen;
std::array<uint8_t, 8> pcounts;
pcounts.fill(0);
while (pos < prop_end_at)
{
const Mqtt5Properties prop = static_cast<Mqtt5Properties>(readUint8());
switch (prop)
{
case Mqtt5Properties::SessionExpiryInterval:
if (pcounts[0]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.session_expire = std::min<uint32_t>(readFourBytesToUint32(), settings.getExpireSessionAfterSeconds());
break;
case Mqtt5Properties::ReceiveMaximum:
if (pcounts[1]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.client_receive_max = std::min<int16_t>(readTwoBytesToUInt16(), result.client_receive_max);
break;
case Mqtt5Properties::MaximumPacketSize:
if (pcounts[2]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.max_outgoing_packet_size = std::min<uint32_t>(readFourBytesToUint32(), result.max_outgoing_packet_size);
break;
case Mqtt5Properties::TopicAliasMaximum:
if (pcounts[3]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.max_outgoing_topic_aliases = std::min<uint16_t>(readTwoBytesToUInt16(), settings.maxOutgoingTopicAliasValue);
break;
case Mqtt5Properties::RequestResponseInformation:
{
if (pcounts[4]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
const uint8_t x = readUint8();
if (x > 1)
throw ProtocolError(propertyToString(prop) + " must be 0 or 1", ReasonCodes::ProtocolError);
result.request_response_information = static_cast<bool>(x);
break;
}
case Mqtt5Properties::RequestProblemInformation:
{
if (pcounts[5]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
const uint8_t x = readUint8();
if (x > 1)
throw ProtocolError(propertyToString(prop) + " must be 0 or 1", ReasonCodes::ProtocolError);
result.request_problem_information = static_cast<bool>(x);
break;
}
case Mqtt5Properties::UserProperty:
{
// We (ab)use the publishData for the user properties, because it's there.
std::string key = readBytesToString();
std::string val = readBytesToString();
this->publishData.addUserProperty(std::move(key), std::move(val));
break;
}
case Mqtt5Properties::AuthenticationMethod:
{
if (pcounts[6]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.authenticationMethod = readBytesToString();
break;
}
case Mqtt5Properties::AuthenticationData:
{
if (pcounts[7]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.authenticationData = readBytesToString(false);
break;
}
default:
throw ProtocolError("Invalid connect property.", ReasonCodes::ProtocolError);
}
}
}
if (result.authenticationMethod.empty() && !result.authenticationData.empty())
throw ProtocolError("Including authentication data when there is no authentication method is not allowed", 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)
{
const size_t proplen = decodeVariableByteIntAtPos();
const size_t prop_end_at = pos + proplen;
std::array<uint8_t, 8> pcounts;
pcounts.fill(0);
while (pos < prop_end_at)
{
const Mqtt5Properties prop = static_cast<Mqtt5Properties>(readUint8());
switch (prop)
{
case Mqtt5Properties::WillDelayInterval:
if (pcounts[0]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.willpublish.will_delay = readFourBytesToUint32();
break;
case Mqtt5Properties::PayloadFormatIndicator:
if (pcounts[1]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.willpublish.payloadUtf8 = static_cast<bool>(readByte());
break;
case Mqtt5Properties::ContentType:
{
if (pcounts[2]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.willpublish.contentType = readBytesToString();
break;
}
case Mqtt5Properties::ResponseTopic:
{
if (pcounts[3]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.willpublish.responseTopic = readBytesToString(true, true);
if (result.willpublish.responseTopic->empty())
throw ProtocolError("Response topic in will cannot be empty", ReasonCodes::ProtocolError);
break;
}
case Mqtt5Properties::MessageExpiryInterval:
{
if (pcounts[4]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
const uint32_t expiresAfter = readFourBytesToUint32();
result.willpublish.setExpireAfter(expiresAfter);
break;
}
case Mqtt5Properties::CorrelationData:
{
if (pcounts[5]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.willpublish.correlationData = readBytesToString(false);
break;
}
case Mqtt5Properties::UserProperty:
{
std::string key = readBytesToString();
std::string val = readBytesToString();
result.willpublish.addUserProperty(std::move(key), std::move(val));
break;
}
default:
throw ProtocolError("Invalid will property in connect.", ReasonCodes::ProtocolError);
}
}
}
result.willpublish.topic = readBytesToString(true, true);
if (result.willpublish.topic.empty())
{
logger->log(LOG_WARNING) << "Empty will topic is not allowed. Dropping will for client " << sender->repr() << ".";
result.will_flag = false;
}
uint16_t will_payload_length = readTwoBytesToUInt16();
result.willpublish.payload = std::string(readBytes(will_payload_length), will_payload_length);
if (result.willpublish.payloadUtf8 && !isValidUtf8Generic(result.willpublish.payload))
{
throw ProtocolError("Will payload announced as UTF8, but it's not valid.", ReasonCodes::PayloadFormatInvalid);
}
}
else
{
if (result.will_retain)
throw ProtocolError("Will retain bit can't be set without will.", ReasonCodes::ProtocolError);
if (result.will_qos != 0)
throw ProtocolError("Will QoS must be 0 when there is no will.", ReasonCodes::ProtocolError);
}
if (user_name_flag)
{
// Usernames must be UTF-8, but we defer that check so we can give proper a CONNACK, and continue parsing.
result.username = readBytesToString(false);
if (result.username.value().empty())
{
if (settings.zeroByteUsernameIsAnonymous)
result.username.reset();
else
throw ProtocolError("Attempting anonymous login with zero byte username. See config option 'zero_byte_username_is_anonymous'.",
ReasonCodes::BadUserNameOrPassword);
}
}
if (result.username)
{
result.willpublish.username = result.username.value();
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 && !user_name_flag)
{
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);
}
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;
std::array<uint8_t, 16> pcounts;
pcounts.fill(0);
while (pos < prop_end_at)
{
const Mqtt5Properties prop = static_cast<Mqtt5Properties>(readUint8());
switch (prop)
{
case Mqtt5Properties::SessionExpiryInterval:
if (pcounts[0]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.session_expire = std::min<uint32_t>(readFourBytesToUint32(), result.session_expire);
break;
case Mqtt5Properties::ReceiveMaximum:
if (pcounts[1]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.client_receive_max = std::min<int16_t>(readTwoBytesToUInt16(), result.client_receive_max);
break;
case Mqtt5Properties::MaximumQoS:
if (pcounts[2]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.max_qos = std::min<uint8_t>(readUint8(), result.max_qos);
break;
case Mqtt5Properties::RetainAvailable:
if (pcounts[3]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.retained_available = static_cast<bool>(readByte());
break;
case Mqtt5Properties::MaximumPacketSize:
if (pcounts[4]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.max_outgoing_packet_size = std::min<uint32_t>(readFourBytesToUint32(), result.max_outgoing_packet_size);
break;
case Mqtt5Properties::AssignedClientIdentifier:
if (pcounts[5]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.assigned_client_id = readBytesToString();
break;
case Mqtt5Properties::TopicAliasMaximum:
if (pcounts[6]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.max_outgoing_topic_aliases = std::min<uint16_t>(readTwoBytesToUInt16(), settings.maxOutgoingTopicAliasValue);
break;
case Mqtt5Properties::ReasonString:
{
if (pcounts[7]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
const std::string reason = readBytesToString();
logger->logf(LOG_NOTICE, "ConnAck reason string: %s", reason.c_str());
break;
}
case Mqtt5Properties::UserProperty:
{
std::string key = readBytesToString();
std::string value = readBytesToString();
break;
}
case Mqtt5Properties::WildcardSubscriptionAvailable:
if (pcounts[8]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
readByte();
break;
case Mqtt5Properties::SubscriptionIdentifierAvailable:
if (pcounts[9]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
readByte();
break;
case Mqtt5Properties::SharedSubscriptionAvailable:
if (pcounts[10]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);
result.shared_subscriptions_available = !!readByte();
break;
case Mqtt5Properties::ServerKeepAlive:
if (pcounts[11]++ > 0)
throw ProtocolError("Can't specify " + propertyToString(prop) + " more than once", ReasonCodes::ProtocolError);