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XmppSocket: Parse whole stream through QXmlStreamReader
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@lnjX
lnjX committed Aug 20, 2024
1 parent 6bb28e3 commit 2a7fcad
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Showing 12 changed files with 258 additions and 133 deletions.
274 changes: 177 additions & 97 deletions src/base/Stream.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,8 @@ StreamOpen StreamOpen::fromXml(QXmlStreamReader &reader)

out.from = attribute({}, u"from");
out.to = attribute({}, u"to");
out.id = attribute({}, u"id");
out.version = attribute({}, u"version");

const auto namespaceDeclarations = reader.namespaceDeclarations();
for (const auto &ns : namespaceDeclarations) {
Expand All @@ -58,11 +60,10 @@ void StreamOpen::toXml(QXmlStreamWriter *writer) const
{
writer->writeStartDocument();
writer->writeStartElement(QSL65("stream:stream"));
if (!from.isEmpty()) {
writer->writeAttribute(QSL65("from"), from);
}
writer->writeAttribute(QSL65("to"), to);
writer->writeAttribute(QSL65("version"), QSL65("1.0"));
writeOptionalXmlAttribute(writer, u"from", from);
writeOptionalXmlAttribute(writer, u"to", to);
writeOptionalXmlAttribute(writer, u"id", id);
writeOptionalXmlAttribute(writer, u"version", version);
writer->writeDefaultNamespace(xmlns);
writer->writeNamespace(toString65(ns_stream), QSL65("stream"));
writer->writeCharacters({});
Expand Down Expand Up @@ -170,6 +171,88 @@ std::variant<StreamErrorElement, QXmppError> StreamErrorElement::fromDom(const Q
}
/// \endcond

DomReader::State DomReader::process(QXmlStreamReader &r)
{
while (true) {
switch (r.tokenType()) {
case QXmlStreamReader::Invalid:
// error received
if (r.error() == QXmlStreamReader::PrematureEndOfDocumentError) {
return Unfinished;
}
return ErrorOccurred;
case QXmlStreamReader::StartElement: {
qDebug() << "start element token";
auto child = r.prefix().isNull()
? doc.createElement(r.name().toString())
: doc.createElementNS(r.namespaceUri().toString(), r.qualifiedName().toString());

// xmlns attribute
const auto nsDeclarations = r.namespaceDeclarations();
for (const auto &ns : nsDeclarations) {
if (ns.prefix().isEmpty()) {
child.setAttribute(QStringLiteral("xmlns"), ns.namespaceUri().toString());
} else {
// namespace declarations are not supported in XMPP
qDebug() << "err namespace decl";
return ErrorOccurred;
}
}

// other attributes
const auto attributes = r.attributes();
for (const auto &a : attributes) {
child.setAttribute(a.name().toString(), a.value().toString());
}

if (currentElement.isNull()) {
doc.appendChild(child);
} else {
currentElement.appendChild(child);
}
depth++;
currentElement = child;
break;
}
case QXmlStreamReader::EndElement:
qDebug() << "end element token";
if (depth == 0) {
qDebug() << "depth == 0";
return ErrorOccurred;
}

currentElement = currentElement.parentNode().toElement();
depth--;
qDebug() << "depth" << depth;
if (depth == 0) {
return Finished;
}
break;
case QXmlStreamReader::Characters:
if (depth == 0) {
qDebug() << "depth == 0";
return ErrorOccurred;
}

currentElement.appendChild(doc.createTextNode(r.text().toString()));
break;
case QXmlStreamReader::NoToken:
// skip
break;
case QXmlStreamReader::StartDocument:
case QXmlStreamReader::EndDocument:
case QXmlStreamReader::Comment:
case QXmlStreamReader::DTD:
case QXmlStreamReader::EntityReference:
case QXmlStreamReader::ProcessingInstruction:
qDebug() << "not allowed";
// not allowed or unexpected
return ErrorOccurred;
}
r.readNext();
}
}

XmppSocket::XmppSocket(QObject *parent)
: QXmppLoggable(parent)
{
Expand All @@ -189,16 +272,16 @@ void XmppSocket::setSocket(QSslSocket *socket)

// do not emit started() with direct TLS (this happens in encrypted())
if (!m_directTls) {
m_dataBuffer.clear();
m_streamOpenElement.clear();
m_reader.clear();
m_streamReceived = false;
Q_EMIT started();
}
});
QObject::connect(socket, &QSslSocket::encrypted, this, [this]() {
debug(u"Socket encrypted"_s);
// this happens with direct TLS or STARTTLS
m_dataBuffer.clear();
m_streamOpenElement.clear();
m_reader.clear();
m_streamReceived = false;
Q_EMIT started();
});
QObject::connect(socket, &QSslSocket::errorOccurred, this, [this](QAbstractSocket::SocketError) {
Expand Down Expand Up @@ -256,102 +339,99 @@ bool XmppSocket::sendData(const QByteArray &data)

void XmppSocket::processData(const QString &data)
{
// As we may only have partial XML content, we need to cache the received
// data until it has been successfully parsed. In case it can't be parsed,
//
// There are only two small problems with the current strategy:
// * When we receive a full stanza + a partial one, we can't parse the
// first stanza until another stanza arrives that is complete.
// * We don't know when we received invalid XML (would cause a growing
// cache and a timeout after some time).
// However, both issues could only be solved using an XML stream reader
// which would cause many other problems since we don't actually use it for
// parsing the content.
m_dataBuffer.append(data);

//
// Check for whitespace pings
//
if (m_dataBuffer.isEmpty() || m_dataBuffer.trimmed().isEmpty()) {
m_dataBuffer.clear();

if (data.isEmpty()) {
qDebug() << "empty ping received";
logReceived({});
Q_EMIT stanzaReceived(QDomElement());
return;
}

//
// Check whether we received a stream open or closing tag
//
static const QRegularExpression streamStartRegex(uR"(^(<\?xml.*\?>)?\s*<stream:stream[^>]*>)"_s);
static const QRegularExpression streamEndRegex(u"</stream:stream>$"_s);

auto streamOpenMatch = streamStartRegex.match(m_dataBuffer);
bool hasStreamOpen = streamOpenMatch.hasMatch();

bool hasStreamClose = streamEndRegex.match(m_dataBuffer).hasMatch();

//
// The stream start/end and stanza packets can't be parsed without any
// modifications with QDomDocument. This is because of multiple reasons:
// * The <stream:stream> open element is not considered valid without the
// closing tag.
// * Only the closing tag is of course not valid too.
// * Stanzas/Nonzas need to have the correct stream namespaces set:
// * For being able to parse <stream:features/>
// * For having the correct namespace (e.g. 'jabber:client') set to
// stanzas and their child elements (e.g. <body/> of a message).
//
// The wrapping strategy looks like this:
// * The stream open tag is cached once it arrives, for later access
// * Incoming XML that has no <stream> open tag will be prepended by the
// cached <stream> tag.
// * Incoming XML that has no <stream> close tag will be appended by a
// generic string "</stream:stream>"
//
// The result is parsed by QDomDocument and the child elements of the stream
// are processed. In case the received data contained a stream open tag,
// the stream is processed (before the stanzas are processed). In case we
// received a </stream> closing tag, the connection is closed.
//
auto wrappedStanzas = m_dataBuffer;
if (!hasStreamOpen) {
wrappedStanzas.prepend(m_streamOpenElement);
}
if (!hasStreamClose) {
wrappedStanzas.append(u"</stream:stream>"_s);
}

//
// Try to parse the wrapped XML
//
QDomDocument doc;
if (!doc.setContent(wrappedStanzas, true)) {
return;
}

//
// Success: We can clear the buffer and send a 'received' log message
//
logReceived(m_dataBuffer);
m_dataBuffer.clear();

// process stream start
if (hasStreamOpen) {
m_streamOpenElement = streamOpenMatch.captured();
Q_EMIT streamReceived(doc.documentElement());
}

// process stanzas
auto stanza = doc.documentElement().firstChildElement();
for (; !stanza.isNull(); stanza = stanza.nextSiblingElement()) {
Q_EMIT stanzaReceived(stanza);
// log data received and process
logReceived(data);
m_reader.addData(data);

// we're still reading a previously started top-level element
if (m_domReader) {
m_reader.readNext();
switch (m_domReader->process(m_reader)) {
case DomReader::Finished:
Q_EMIT stanzaReceived(m_domReader->element());
m_domReader.reset();
break;
case DomReader::Unfinished:
return;
case DomReader::ErrorOccurred:
// emit error
break;
}
}

// process stream end
if (hasStreamClose) {
Q_EMIT streamClosed();
}
do {
switch (m_reader.readNext()) {
case QXmlStreamReader::Invalid:
// error received
if (m_reader.error() != QXmlStreamReader::PrematureEndOfDocumentError) {
// emit error
}
break;
case QXmlStreamReader::StartDocument:
// pre-stream open
break;
case QXmlStreamReader::EndDocument:
// post-stream close
break;
case QXmlStreamReader::StartElement:
// stream open or stream-level element
if (m_reader.name() == u"stream" && m_reader.namespaceUri() == ns_stream) {
m_streamReceived = true;
Q_EMIT streamReceived(StreamOpen::fromXml(m_reader));
} else if (!m_streamReceived) {
// error: expected stream open element
qDebug() << "err no stream recevied";
} else {
qDebug() << "start el";
// parse top-level stream element
m_domReader = DomReader();

switch (m_domReader->process(m_reader)) {
case DomReader::Finished:
Q_EMIT stanzaReceived(m_domReader->element());
m_domReader.reset();
break;
case DomReader::Unfinished:
qDebug() << "unfi";
return;
case DomReader::ErrorOccurred:
qDebug() << "el err";
// emit error
break;
}
}
break;
case QXmlStreamReader::EndElement:
// end of stream
Q_EMIT streamClosed();
break;
case QXmlStreamReader::Characters:
if (m_reader.isWhitespace()) {
logReceived({});
Q_EMIT stanzaReceived(QDomElement());
} else {
// invalid: emit error
}
break;
case QXmlStreamReader::NoToken:
// skip
break;
case QXmlStreamReader::Comment:
case QXmlStreamReader::DTD:
case QXmlStreamReader::EntityReference:
case QXmlStreamReader::ProcessingInstruction:
// not allowed in XMPP: emit error
break;
}
} while (!m_reader.hasError());
}

} // namespace QXmpp::Private
5 changes: 5 additions & 0 deletions src/base/Stream.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@

#include <optional>

#include <QMetaType>
#include <QString>

class QDomElement;
Expand All @@ -21,6 +22,8 @@ struct StreamOpen {

QString to;
QString from;
QString id;
QString version;
QString xmlns;
};

Expand All @@ -44,4 +47,6 @@ struct CsiInactive {

} // namespace QXmpp::Private

Q_DECLARE_METATYPE(QXmpp::Private::StreamOpen)

#endif // STREAM_H
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