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Network-chat: Fix remote peer making multiple connections

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The system was just treating IP (and optionally port) as a unique
identifier, so if a peer had multiple possible paths to a client they
would connect multiple times.

This fixes that by generating using QUuid in each client.
We then use this during broadcast, replacing the username we
sent before (which was not used), and as part of the greeting.
The greeting now is more complex, since we need to send both
username and the ID.

Change-Id: I6c6c2ffd5198406aad48445a68dd6aab36de69c0
Reviewed-by: Konrad Kujawa <konrad.kujawa@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
This commit is contained in:
Mårten Nordheim 2023-06-14 18:48:19 +02:00
parent 5651be517a
commit 226d06402b
6 changed files with 77 additions and 39 deletions
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30
examples/network/network-chat/client.cpp
View File

@ -37,27 +37,14 @@ QString Client::nickName() const
+ ':' + QString::number(server.serverPort());
}
bool Client::hasConnection(const QHostAddress &senderIp, int senderPort) const
bool Client::hasConnection(const QByteArray &peerUniqueId) const
{
auto [begin, end] = peers.equal_range(senderIp);
if (begin == peers.constEnd())
return false;
if (senderPort == -1)
return true;
for (; begin != end; ++begin) {
Connection *connection = *begin;
if (connection->peerPort() == senderPort)
return true;
}
return false;
return peers.contains(peerUniqueId);
}
void Client::newConnection(Connection *connection)
{
connection->setGreetingMessage(peerManager->userName());
connection->setGreetingMessage(peerManager->userName(), peerManager->uniqueId());
connect(connection, &Connection::errorOccurred, this, &Client::connectionError);
connect(connection, &Connection::disconnected, this, &Client::disconnected);
@ -67,13 +54,18 @@ void Client::newConnection(Connection *connection)
void Client::readyForUse()
{
Connection *connection = qobject_cast<Connection *>(sender());
if (!connection || hasConnection(connection->peerAddress(), connection->peerPort()))
if (!connection || hasConnection(connection->uniqueId())) {
if (connection) {
connection->disconnectFromHost();
connection->deleteLater();
}
return;
}
connect(connection, &Connection::newMessage,
this, &Client::newMessage);
peers.insert(connection->peerAddress(), connection);
peers.insert(connection->uniqueId(), connection);
QString nick = connection->name();
if (!nick.isEmpty())
emit newParticipant(nick);
@ -93,7 +85,7 @@ void Client::connectionError(QAbstractSocket::SocketError /* socketError */)
void Client::removeConnection(Connection *connection)
{
if (peers.remove(connection->peerAddress(), connection) > 0) {
if (peers.remove(connection->uniqueId(), connection) > 0) {
QString nick = connection->name();
if (!nick.isEmpty())
emit participantLeft(nick);

4
examples/network/network-chat/client.h
View File

@ -21,7 +21,7 @@ public:
void sendMessage(const QString &message);
QString nickName() const;
bool hasConnection(const QHostAddress &senderIp, int senderPort = -1) const;
bool hasConnection(const QByteArray &peerUniqueId) const;
signals:
void newMessage(const QString &from, const QString &message);
@ -39,7 +39,7 @@ private:
PeerManager *peerManager;
Server server;
QMultiHash<QHostAddress, Connection *> peers;
QMultiHash<QByteArray, Connection *> peers;
};
#endif

41
examples/network/network-chat/connection.cpp
View File

@ -21,7 +21,7 @@ static const int PingInterval = 5 * 1000;
* plaintext = { 0 => text }
* ping = { 1 => null }
* pong = { 2 => null }
* greeting = { 3 => text }
* greeting = { 3 => { text, bytes } }
*/
Connection::Connection(QObject *parent)
@ -60,9 +60,15 @@ QString Connection::name() const
return username;
}
void Connection::setGreetingMessage(const QString &message)
void Connection::setGreetingMessage(const QString &message, const QByteArray &uniqueId)
{
greetingMessage = message;
localUniqueId = uniqueId;
}
QByteArray Connection::uniqueId() const
{
return peerUniqueId;
}
bool Connection::sendMessage(const QString &message)
@ -118,9 +124,31 @@ void Connection::processReadyRead()
reader.next();
} else {
// Current state: read command payload
if (currentDataType == Greeting) {
if (state == ReadingGreeting) {
if (!reader.isContainer() || !reader.isLengthKnown() || reader.length() != 2)
break; // protocol error
state = ProcessingGreeting;
reader.enterContainer();
}
if (state != ProcessingGreeting)
break; // protocol error
if (reader.isString()) {
auto r = reader.readString();
buffer += r.data;
} else if (reader.isByteArray()) {
auto r = reader.readByteArray();
peerUniqueId += r.data;
if (r.status == QCborStreamReader::EndOfString) {
reader.leaveContainer();
processGreeting();
}
}
if (state == ProcessingGreeting)
continue;
} else if (reader.isString()) {
auto r = reader.readString();
buffer += r.data;
if (r.status != QCborStreamReader::EndOfString)
continue;
} else if (reader.isNull()) {
@ -136,15 +164,9 @@ void Connection::processReadyRead()
transferTimerId = -1;
}
if (state == ReadingGreeting) {
if (currentDataType != Greeting)
break; // protocol error
processGreeting();
} else {
processData();
}
}
}
if (reader.lastError() != QCborError::EndOfFile)
abort(); // parse error
@ -172,7 +194,10 @@ void Connection::sendGreetingMessage()
writer.startMap(1);
writer.append(Greeting);
writer.startArray(2);
writer.append(greetingMessage);
writer.append(localUniqueId);
writer.endArray();
writer.endMap();
isGreetingMessageSent = true;

7
examples/network/network-chat/connection.h
View File

@ -20,6 +20,7 @@ public:
enum ConnectionState {
WaitingForGreeting,
ReadingGreeting,
ProcessingGreeting,
ReadyForUse
};
enum DataType {
@ -35,9 +36,11 @@ public:
~Connection();
QString name() const;
void setGreetingMessage(const QString &message);
void setGreetingMessage(const QString &message, const QByteArray &uniqueId);
bool sendMessage(const QString &message);
QByteArray uniqueId() const;
signals:
void readyForUse();
void newMessage(const QString &from, const QString &message);
@ -62,6 +65,8 @@ private:
QTimer pingTimer;
QElapsedTimer pongTime;
QString buffer;
QByteArray localUniqueId;
QByteArray peerUniqueId;
ConnectionState state = WaitingForGreeting;
DataType currentDataType = Undefined;
int transferTimerId = -1;

26
examples/network/network-chat/peermanager.cpp
View File

@ -7,6 +7,7 @@
#include "peermanager.h"
#include <QNetworkInterface>
#include <QUuid>
static const qint32 BroadcastInterval = 2000;
static const unsigned broadcastPort = 45000;
@ -27,6 +28,11 @@ PeerManager::PeerManager(Client *client)
if (username.isEmpty())
username = "unknown";
// We generate a unique per-process identifier so we can avoid multiple
// connections to/from the same remote peer as well as ignore our own
// broadcasts.
localUniqueId = QUuid::createUuid().toByteArray();
updateAddresses();
broadcastSocket.bind(QHostAddress::Any, broadcastPort, QUdpSocket::ShareAddress
@ -49,6 +55,11 @@ QString PeerManager::userName() const
return username;
}
QByteArray PeerManager::uniqueId() const
{
return localUniqueId;
}
void PeerManager::startBroadcasting()
{
broadcastTimer.start();
@ -65,7 +76,7 @@ void PeerManager::sendBroadcastDatagram()
{
QCborStreamWriter writer(&datagram);
writer.startArray(2);
writer.append(username);
writer.append(localUniqueId);
writer.append(serverPort);
writer.endArray();
}
@ -92,6 +103,7 @@ void PeerManager::readBroadcastDatagram()
continue;
int senderServerPort;
QByteArray peerUniqueId;
{
// decode the datagram
QCborStreamReader reader(datagram);
@ -101,10 +113,12 @@ void PeerManager::readBroadcastDatagram()
continue;
reader.enterContainer();
if (reader.lastError() != QCborError::NoError || !reader.isString())
if (reader.lastError() != QCborError::NoError || !reader.isByteArray())
continue;
while (reader.readString().status == QCborStreamReader::Ok) {
// we don't actually need the username right now
auto r = reader.readByteArray();
while (r.status == QCborStreamReader::Ok) {
peerUniqueId = r.data;
r = reader.readByteArray();
}
if (reader.lastError() != QCborError::NoError || !reader.isUnsignedInteger())
@ -112,10 +126,10 @@ void PeerManager::readBroadcastDatagram()
senderServerPort = reader.toInteger();
}
if (isLocalHostAddress(senderIp) && senderServerPort == serverPort)
if (peerUniqueId == localUniqueId)
continue;
if (!client->hasConnection(senderIp)) {
if (!client->hasConnection(peerUniqueId)) {
Connection *connection = new Connection(this);
emit newConnection(connection);
connection->connectToHost(senderIp, senderServerPort);

2
examples/network/network-chat/peermanager.h
View File

@ -22,6 +22,7 @@ public:
void setServerPort(int port);
QString userName() const;
QByteArray uniqueId() const;
void startBroadcasting();
bool isLocalHostAddress(const QHostAddress &address) const;
@ -41,6 +42,7 @@ private:
QUdpSocket broadcastSocket;
QTimer broadcastTimer;
QString username;
QByteArray localUniqueId;
int serverPort = 0;
};