fix(GODT-2966): Allow permissive parsing of MediaType parameters for import.

pkg/message/parser.go

@@ -547,8 +547,8 @@ func parseAttachment(h message.Header, body []byte) (Attachment, error) {
 		return Attachment{}, err
 	}
 	att.Header = mimeHeader
+	mimeType, mimeTypeParams, err := pmmime.ParseMediaType(h.Get("Content-Type"))
 
-	mimeType, mimeTypeParams, err := h.ContentType()
 	if err != nil {
 		return Attachment{}, err
 	}
@@ -558,7 +558,8 @@ func parseAttachment(h message.Header, body []byte) (Attachment, error) {
 	// Prefer attachment name from filename param in content disposition.
 	// If not available, try to get it from name param in content type.
 	// Otherwise fallback to attachment.bin.
-	if disp, dispParams, err := h.ContentDisposition(); err == nil {
+	disp, dispParams, err := pmmime.ParseMediaType(h.Get("Content-Disposition"))
+	if err == nil {
 		att.Disposition = proton.Disposition(disp)
 
 		if filename, ok := dispParams["filename"]; ok {
@@ -585,7 +586,7 @@ func parseAttachment(h message.Header, body []byte) (Attachment, error) {
 	// (This is necessary because some clients don't set Content-Disposition at all,
 	// so we need to rely on other information to deduce if it's inline or attachment.)
 	if h.Has("Content-Disposition") {
-		disp, _, err := h.ContentDisposition()
+		disp, _, err := pmmime.ParseMediaType(h.Get("Content-Disposition"))
 		if err != nil {
 			return Attachment{}, err
 		}

pkg/message/parser_test.go

@@ -539,6 +539,18 @@ func TestParseMultipartAlternativeLatin1(t *testing.T) {
 	assert.Equal(t, "*aoeuaoeu*\n\n", string(m.PlainBody))
 }
 
+func TestParseMultipartAttachmentEncodedButUnquoted(t *testing.T) {
+	f := getFileReader("multipart_attachment_encoded_no_quote.eml")
+
+	p, err := parser.New(f)
+	require.NoError(t, err)
+
+	m, err := ParseWithParser(p, false)
+	require.NoError(t, err)
+	assert.Equal(t, `"Bridge Test" <bridgetest@pm.test>`, m.Sender.String())
+	assert.Equal(t, `"Internal Bridge" <bridgetest@protonmail.com>`, m.ToList[0].String())
+}
+
 func TestParseWithTrailingEndOfMailIndicator(t *testing.T) {
 	f := getFileReader("text_html_trailing_end_of_mail.eml")
 

pkg/message/testdata/multipart_attachment_encoded_no_quote.eml

@@ -0,0 +1,27 @@
+From: Bridge Test <bridgetest@pm.test>
+Date: 01 Jan 1980 00:00:00 +0000
+To: Internal Bridge <bridgetest@protonmail.com>
+Subject: Message with attachment name
+Content-type: multipart/mixed; boundary="boundary"
+Received: by 2002:0:0:0:0:0:0:0 with SMTP id 0123456789abcdef; Wed, 30 Dec 2020 01:23:45 0000
+
+This is a multi-part message in MIME format.
+
+--boundary
+Content-Type: text/plain
+
+Hello
+
+--boundary
+Content-Type: text/html; charset=utf-8
+Content-Transfer-Encoding: 7bit
+
+<h1> HELLO </h1>
+
+--boundary
+Content-Type: application/pdf; name==?US-ASCII?Q?filename?=
+Content-Disposition: attachment; filename==?US-ASCII?Q?filename?=
+
+somebytes
+
+--boundary--

pkg/mime/encoding.go

@@ -256,6 +256,10 @@ func DecodeCharset(original []byte, contentType string) ([]byte, error) {
 
 // ParseMediaType from MIME doesn't support RFC2231 for non asci / utf8 encodings so we have to pre-parse it.
 func ParseMediaType(v string) (mediatype string, params map[string]string, err error) {
-	v, _ = changeEncodingAndKeepLastParamDefinition(v)
+	decoded, err := DecodeHeader(v)
+	if err != nil {
+		return "", nil, err
+	}
+	v, _ = changeEncodingAndKeepLastParamDefinition(decoded)
 	return mime.ParseMediaType(v)
 }