feat: add MimeParser with GMime and safe attachment naming

1 files changed, 64 insertions, 0 deletions

diff --git a/src/mimeparser.h b/src/mimeparser.h
new file mode 100644
index 0000000..27a239f
--- /dev/null
+++ b/src/mimeparser.h
@@ -0,0 +1,64 @@
+#pragma once
+
+#include <QByteArray>
+#include <QHash>
+#include <QList>
+#include <QString>
+
+/// An inline part referenced by a cid: URL from the HTML body.
+struct InlinePart
+{
+    QString mimeType;
+    QByteArray data;
+};
+
+struct Attachment
+{
+    QString filename;   ///< As it appeared in the message. Untrusted.
+    QString mimeType;
+    QByteArray data;
+
+    /// filename reduced to a basename safe to join onto a directory.
+    /// Attacker-controlled input: a filename may contain path separators or
+    /// "..", so anything that could escape the target directory is stripped.
+    /// Returns a generated name when nothing usable remains.
+    QString safeFilename() const;
+
+    /// Writes the attachment into directory. Returns the full path written, or
+    /// an empty string on failure with *error set.
+    QString saveTo(const QString &directory, QString *error) const;
+};
+
+struct ParsedMessage
+{
+    bool ok = false;
+    QString error;
+
+    QString subject;
+    QString from;
+    QString to;
+    QString cc;
+    QString date;
+    QString messageId;
+
+    QString plainBody;
+    QString htmlBody;
+
+    QHash<QString, InlinePart> inlineParts;  ///< Keyed by Content-ID, no <>.
+    QList<Attachment> attachments;
+
+    bool hasHtml() const { return !htmlBody.isEmpty(); }
+};
+
+/// Parses a single message file using GMime.
+///
+/// Hand-rolling this would mean reimplementing RFC 2047 encoded words, RFC 2231
+/// parameter continuations, transfer encodings, and charset conversion, plus
+/// tolerance for malformed real-world mail.
+class MimeParser
+{
+public:
+    MimeParser();
+
+    ParsedMessage parse(const QString &filePath) const;
+};