feat: add deny-by-default web request interceptor

1 files changed, 42 insertions, 0 deletions

diff --git a/src/requestinterceptor.h b/src/requestinterceptor.h
new file mode 100644
index 0000000..817a4d1
--- /dev/null
+++ b/src/requestinterceptor.h
@@ -0,0 +1,42 @@
+#pragma once
+
+#include <QSet>
+#include <QUrl>
+#include <QWebEngineUrlRequestInterceptor>
+
+/// Deny-by-default request policy for the message view.
+///
+/// A message body is untrusted input from a stranger. Everything is blocked
+/// unless explicitly permitted: remote loads leak the fact that a message was
+/// read (tracking pixels) and file: loads would expose the local filesystem.
+class RequestInterceptor : public QWebEngineUrlRequestInterceptor
+{
+    Q_OBJECT
+public:
+    explicit RequestInterceptor(QObject *parent = nullptr);
+
+    /// The whole policy, as a pure function so it can be tested directly.
+    bool shouldAllow(const QUrl &url);
+
+    void interceptRequest(QWebEngineUrlRequestInfo &info) override;
+
+    /// Content-IDs belonging to the currently displayed message.
+    void setAllowedCids(const QSet<QString> &cids) { m_allowedCids = cids; }
+
+    /// Per-message opt-in, triggered by the user clicking "Load remote content".
+    /// Never persisted, never carried to the next message.
+    void setAllowRemote(bool allow) { m_allowRemote = allow; }
+    bool allowRemote() const { return m_allowRemote; }
+
+    /// True once any request has been denied, so the UI can offer the button.
+    bool blockedAnything() const { return m_blockedAnything; }
+
+    /// Called before rendering a new message: clears both the remote grant and
+    /// the blocked flag.
+    void resetForNewMessage();
+
+private:
+    QSet<QString> m_allowedCids;
+    bool m_allowRemote = false;
+    bool m_blockedAnything = false;
+};