GODT-213: Message Builder

pkg/message/build_rfc822_custom.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2021 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package message
+
+import (
+	"fmt"
+	"mime"
+
+	"github.com/ProtonMail/gopenpgp/v2/constants"
+	"github.com/ProtonMail/gopenpgp/v2/crypto"
+	"github.com/ProtonMail/proton-bridge/pkg/pmapi"
+	"github.com/emersion/go-message"
+)
+
+func writeCustomTextPart(
+	w *message.Writer,
+	msg *pmapi.Message,
+	decError error,
+) error {
+	enc, err := crypto.NewPGPMessageFromArmored(msg.Body)
+	if err != nil {
+		return err
+	}
+
+	arm, err := enc.GetArmoredWithCustomHeaders(
+		fmt.Sprintf("This message could not be decrypted: %v", decError),
+		constants.ArmorHeaderVersion,
+	)
+	if err != nil {
+		return err
+	}
+
+	var hdr message.Header
+
+	hdr.SetContentType(msg.MIMEType, nil)
+
+	part, err := w.CreatePart(hdr)
+	if err != nil {
+		return err
+	}
+
+	if _, err := part.Write([]byte(arm)); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func writeCustomAttachmentPart(
+	w *message.Writer,
+	att *pmapi.Attachment,
+	msg *crypto.PGPMessage,
+	decError error,
+) error {
+	arm, err := msg.GetArmoredWithCustomHeaders(
+		fmt.Sprintf("This attachment could not be decrypted: %v", decError),
+		constants.ArmorHeaderVersion,
+	)
+	if err != nil {
+		return err
+	}
+
+	var hdr message.Header
+
+	hdr.SetContentType("application/pgp-encrypted", map[string]string{"name": mime.QEncoding.Encode("utf-8", att.Name+".pgp")})
+
+	hdr.SetContentDisposition(att.Disposition, map[string]string{"filename": mime.QEncoding.Encode("utf-8", att.Name+".pgp")})
+
+	part, err := w.CreatePart(hdr)
+	if err != nil {
+		return err
+	}
+
+	if _, err := part.Write([]byte(arm)); err != nil {
+		return err
+	}
+
+	return part.Close()
+}