Files
js8call/MessageClient.cpp
2024-11-06 06:28:51 -08:00

289 lines
7.8 KiB
C++

#include "MessageClient.hpp"
#include <stdexcept>
#include <QApplication>
#include <QHostInfo>
#include <QNetworkDatagram>
#include <QQueue>
#include <QSet>
#include <QTimer>
#include <QUdpSocket>
#include "DriftingDateTime.h"
#include "pimpl_impl.hpp"
#include "moc_MessageClient.cpp"
/******************************************************************************/
// Constants
/******************************************************************************/
namespace
{
constexpr auto PING_INTERVAL = std::chrono::seconds(15);
}
/******************************************************************************/
// Private Implementation
/******************************************************************************/
class MessageClient::impl final : public QUdpSocket
{
Q_OBJECT
public:
// Constructor
impl(quint16 const port,
MessageClient * self)
: self_ {self}
, port_ {port}
, ping_ {new QTimer {this}}
{
// Note that With UDP, error reporting is not guaranteed, which is not
// the same as a guarantee of no error reporting. Typically, a packet
// arriving on a port where there is no listener will trigger an ICMP
// Port Unreachable message back to the sender, and some implementations
// e.g., Windows, will report that to the application on the next attempt
// to transmit to the same destination.
connect(this, &QUdpSocket::errorOccurred, [this](SocketError const e)
{
if (e != ConnectionRefusedError)
{
Q_EMIT self_->error (errorString());
}
});
connect(this, &QIODevice::readyRead, this, [this]()
{
while (hasPendingDatagrams())
{
if (auto const datagram = receiveDatagram();
datagram.isValid())
{
try
{
Q_EMIT self_->message (Message::fromJson(datagram.data()));
}
catch (std::exception const & e)
{
Q_EMIT self_->error (QString {"MessageClient exception: %1"}.arg(e.what()));
}
}
}
});
connect(ping_, &QTimer::timeout, this, &impl::ping);
ping_->start(PING_INTERVAL);
}
// Destructor
~impl()
{
abort_host_lookup();
if (port_ && !host_.isNull())
{
send_message({"CLOSE"});
}
}
// Send a ping message, if we have a valid port and host.
void
ping()
{
if (port_ && !host_.isNull())
{
send_message({"PING", "", {
{"NAME", QVariant(QApplication::applicationName())},
{"VERSION", QVariant(QApplication::applicationVersion())},
{"UTC", QVariant(DriftingDateTime::currentDateTimeUtc().toMSecsSinceEpoch())}
}});
}
}
// If the JSON-serialized form of the message isn't exactly the same as
// the one that we last sent, send it and note it as the prior datagram
// sent.
//
// Caller is required to make the determination that our port and host
// are valid prior to calling this function.
void
send_message(Message const & message)
{
if (auto const datagram = message.toJson();
datagram != lastDatagram_)
{
writeDatagram(datagram, host_, port_);
lastDatagram_ = datagram;
}
}
// If we've got a host lookup in flight, but not yet completed, abort it
// and indicate that we no longer have one in flight.
void
abort_host_lookup()
{
if (hostLookupId_ != -1)
{
QHostInfo::abortHostLookup(hostLookupId_);
hostLookupId_ = -1;
}
}
// Abort any current host lookup that might be in flight, and start a new
// host lookup for the provided server name, noting that we have a lookup
// in flight.
//
// If, at the time of host lookup completion, we find ourselves to be the
// active host lookup, and we were able to look up addresses, then use the
// first address associated with the server as our host address, and send
// a ping.
//
// No matter the result of the host lookup, we're going to drain the queue,
// either via sending messages if the host lookup worked, or by clearing it
// if the lookup failed.
void
queue_host_lookup(QString const & name)
{
abort_host_lookup();
hostLookupId_ = QHostInfo::lookupHost(name,
this,
[this](QHostInfo const & info)
{
// This functor is always called in the context of the thread that
// made the call to lookupHost(), so we're safe to modify anything
// that we were safe to modify outside.
if (info.lookupId() == hostLookupId_)
{
hostLookupId_ = -1;
if (auto const & list = info.addresses();
!list.isEmpty())
{
host_ = list.first();
qDebug() << "MessageClient Host:" << host_.toString()
<< "loopback:" << host_.isLoopback()
<< "multicast:" << host_.isMulticast();
if (state() != UnconnectedState) close();
bind(host_.protocol() == IPv6Protocol ? QHostAddress::AnyIPv6
: QHostAddress::AnyIPv4);
if (host_.isMulticast()) joinMulticastGroup(host_);
ping();
if (port_ && !host_.isNull())
{
while (!messageQueue_.isEmpty()) send_message(messageQueue_.dequeue());
}
}
else
{
Q_EMIT self_->error (QString {"Host lookup failed: %1"}.arg(info.errorString()));
messageQueue_.clear();
}
}
});
}
// Data members
MessageClient * self_;
quint16 port_;
QTimer * ping_;
QHostAddress host_;
int hostLookupId_ = -1;
QQueue<Message> messageQueue_;
QByteArray lastDatagram_;
};
/******************************************************************************/
// Implementation
/******************************************************************************/
#include "MessageClient.moc"
// Constructor
MessageClient::MessageClient(QString const & name,
quint16 const port,
QObject * parent)
: QObject {parent}
, m_ {port, this}
{
set_server_name(name);
}
// Host accessor; returns host information for the server. Note
// that this will return an invalid object while a host lookup
// is in flight, so consider thread inertia before relying on
// this; the case may be that information is coming, but it's
// not here just yet.
QHostAddress
MessageClient::server_host() const
{
return m_->host_;
}
// Port accessor; if zero, anything sent to us will be dropped
// on the floor.
quint16
MessageClient::server_port() const
{
return m_->port_;
}
// Set our server name. If the name is empty, then what happens to
// messages provided to us via send() depends on what our port is
// set to. If it's zero, they'll just be dropped on the floor. If
// it's non-zero, they'll be queued until this method is called
// again with a non-empty name.
void
MessageClient::set_server_name(QString const & name)
{
m_->host_.clear();
if (name.isEmpty()) m_->abort_host_lookup();
else m_->queue_host_lookup(name);
}
// Set our port; if zero, no sending will be performed, and anything
// sent us for disposition via send() will be dropped on the floor.
void
MessageClient::set_server_port(quint16 const port)
{
m_->port_ = port;
}
// If we've got a port, i.e., we're supposed to send messages, then queue
// the message for later transmission if we don't have a host yet; attempt
// to send it immediately if we've got a host.
void
MessageClient::send(Message const & message)
{
if (m_->port_)
{
if (m_->host_.isNull()) m_->messageQueue_.enqueue(message);
else m_->send_message(message);
}
}
/******************************************************************************/