logos-protocol/cpp/module_proxy.cpp

#include "module_proxy.h"
#include "logos_provider_interface.h"
#include "token_manager.h"
#include <QDebug>
#include <QByteArray>
#include <QJsonObject>
#include <QJsonValue>
#include <algorithm>

ModuleProxy::ModuleProxy(LogosProviderObject* provider, QObject* parent)
    : QObject(parent)
    , m_provider(provider)
{
    if (m_provider) {
        m_provider->setEventListener([this](const QString& eventName, const QVariantList& data) {
            qDebug() << "[LogosProviderObject] ModuleProxy: forwarding event" << eventName << "as Qt signal";
            // Events may be fired from any thread (e.g. a module's worker/FFI
            // thread), but this object is the QtRemoteObjects source and must be
            // driven from its own thread. Emitting directly from a foreign
            // thread runs QtRO's source serialization there, racing the source
            // socket against a reply being sent from the source thread, which
            // can silently drop the reply.
            //
            // We *always* queue the emission to this object's own thread, never
            // emit inline — even for a same-thread caller. A module that emits an
            // event from inside an async-call-completion callback (e.g. a
            // gather/fan-out completion firing `balances_updated` from within the
            // `__logos_call_complete__` reply dispatch) is on the source thread,
            // so an AutoConnection would run QtRO's source serialization for the
            // event *re-entrantly*, while a reply is still being marshalled on the
            // same stack — corrupting the source and crashing (SIGSEGV). A queued
            // connection defers the emit to the next event-loop turn, after the
            // reply has been sent, so events and replies stay serialized on the
            // thread QtRO owns. Passing `this` as the context also cancels a
            // queued emission if this object is destroyed first.
            QMetaObject::invokeMethod(this, [this, eventName, data]() {
                emit eventResponse(eventName, data);
            }, Qt::QueuedConnection);
        });
        qDebug() << "[LogosProviderObject] ModuleProxy: created, wrapping LogosProviderObject"
                 << m_provider->providerName();
    }
}

ModuleProxy::~ModuleProxy()
{
    qDebug() << "ModuleProxy: destroyed";
}

bool ModuleProxy::saveToken(const QString& from_module_name, const QString& token)
{
    if (from_module_name.isEmpty()) {
        qWarning() << "ModuleProxy: Cannot save token with empty module name";
        return false;
    }
    if (token.isEmpty()) {
        qWarning() << "ModuleProxy: Cannot save empty token for module:" << from_module_name;
        return false;
    }

    m_tokens[from_module_name] = token;
    qDebug() << "ModuleProxy: Token saved for module:" << from_module_name;
    return true;
}

QVariant ModuleProxy::callRemoteMethod(const QString& authToken, const QString& methodName, const QVariantList& args)
{
    if (!m_provider) {
        qWarning() << "ModuleProxy: Cannot call method on null provider:" << methodName;
        return QVariant();
    }

    if (methodName.isEmpty()) {
        qWarning() << "ModuleProxy: Method name cannot be empty";
        return QVariant();
    }

    if (methodName == "getPluginMethods" && args.isEmpty()) {
        return QVariant(getPluginMethods());
    }

    if (methodName == "getPluginEvents" && args.isEmpty()) {
        return QVariant(getPluginEvents());
    }

    if (methodName == "getPluginInterface" && args.isEmpty()) {
        return QVariant(getPluginInterface());
    }
    // NOTE: the three getPlugin* introspection calls above intentionally stay
    // ungated. They expose only the method/event signatures (no business logic
    // or state) and are needed before any token exists — a caller discovers a
    // module's interface as part of the connection handshake, ahead of the
    // capability_module token exchange. Everything past this point is a real
    // business-method dispatch and MUST be authorized.

    if (!isAuthorized(authToken)) {
        qWarning() << "ModuleProxy: rejecting unauthorized call to" << methodName
                   << "- auth token not recognized";
        return QVariant();
    }

    qDebug() << "ModuleProxy: callRemoteMethod" << methodName << "args:" << args;
    return m_provider->callMethod(methodName, args);
}

namespace {
// note: this is to ensure comparison is constant time to prevent timing attacks
// Length-independent constant-time comparison of two tokens. Returns true only
// when both byte sequences are identical. We compare over the longer of the two
// lengths (folding any length difference into the result) so the running time
// does not reveal a correct prefix or the secret's length.
bool constantTimeEquals(const QString& a, const QString& b)
{
    const QByteArray ba = a.toUtf8();
    const QByteArray bb = b.toUtf8();
    const int n = std::max(ba.size(), bb.size());
    // A different length is a mismatch, but keep scanning to stay constant-time.
    int diff = ba.size() ^ bb.size();
    for (int i = 0; i < n; ++i) {
        const unsigned char ca = i < ba.size() ? static_cast<unsigned char>(ba[i]) : 0;
        const unsigned char cb = i < bb.size() ? static_cast<unsigned char>(bb[i]) : 0;
        diff |= (ca ^ cb);
    }
    return diff == 0;
}
} // namespace

bool ModuleProxy::informModuleToken(const QString& authToken, const QString& moduleName, const QString& token)
{
    if (!m_provider) {
        qWarning() << "ModuleProxy: Cannot inform token on null provider";
        return false;
    }

    const QString coreToken = TokenManager::instance().getToken(QStringLiteral("core"));
    const QString capToken  = TokenManager::instance().getToken(QStringLiteral("capability_module"));
    const bool callerIsTrusted =
        (!coreToken.isEmpty() && constantTimeEquals(authToken, coreToken)) ||
        (!capToken.isEmpty()  && constantTimeEquals(authToken, capToken));
    if (authToken.isEmpty() || !callerIsTrusted) {
        qWarning() << "ModuleProxy: rejecting informModuleToken for" << moduleName
                   << "- caller is not the trusted core/capability_module channel";
        return false;
    }

    if (moduleName.isEmpty()) {
        qWarning() << "ModuleProxy: Cannot inform token with empty module name";
        return false;
    }
    if (token.isEmpty()) {
        qWarning() << "ModuleProxy: Cannot inform empty token for module:" << moduleName;
        return false;
    }

    return m_provider->informModuleToken(moduleName, token);
}

bool ModuleProxy::isAuthorized(const QString& authToken) const
{
    // Fail closed: an empty token is never valid, even if some empty value
    // somehow ended up in a token store.
    if (authToken.isEmpty()) {
        return false;
    }

    // A token is valid only if THIS module actually issued it to some caller.
    // Two stores hold issued tokens:
    //   * m_tokens          — legacy per-proxy store (LogosAPIProvider::saveToken)
    //   * TokenManager      — the capability-flow store that informModuleToken
    //                         writes when capability_module mints a token for a
    //                         (caller, target) pair.
    // We scan every issued token with a constant-time compare and never early
    // out, so neither a match position nor the number of issued tokens leaks
    // through timing.
    bool authorized = false;
    for (auto it = m_tokens.constBegin(); it != m_tokens.constEnd(); ++it) {
        authorized |= constantTimeEquals(authToken, it.value());
    }
    for (const QString& key : TokenManager::instance().getTokenKeys()) {
        authorized |= constantTimeEquals(authToken, TokenManager::instance().getToken(key));
    }
    return authorized;
}

namespace {
// getMethods() returns the module's full interface — both methods and events,
// each tagged with a "type" ("method"/"event"). Split it back out. An entry
// with no "type" counts as a method, so modules built against the pre-events
// SDK (whose getMethods() contains no events) report zero events, not a crash.
QJsonArray filterInterface(const QJsonArray& interface, bool keepEvents)
{
    QJsonArray out;
    for (const QJsonValue& v : interface) {
        const bool isEvent =
            v.toObject().value(QStringLiteral("type")).toString() == QStringLiteral("event");
        if (isEvent == keepEvents) out.append(v);
    }
    return out;
}
} // namespace

QJsonArray ModuleProxy::getPluginInterface()
{
    if (!m_provider) return QJsonArray();

    qDebug() << "[LogosProviderObject] ModuleProxy: calling LogosProviderObject::getMethods()";
    return m_provider->getMethods();
}

QJsonArray ModuleProxy::getPluginMethods()
{
    return filterInterface(getPluginInterface(), /*keepEvents=*/false);
}

QJsonArray ModuleProxy::getPluginEvents()
{
    return filterInterface(getPluginInterface(), /*keepEvents=*/true);
}

#include "moc_module_proxy.cpp"