Bugfix: parse email with no text content

decoders.go

@@ -129,34 +129,56 @@ func decodeInlineFile(part *multipart.Part, cte ContentTransferEncoding) (Inline
 	return ifl, nil
 }
 
-func decodeAttachedFile(part *multipart.Part, cte ContentTransferEncoding) (AttachedFile, error) {
+func decodeAttachmentFileFromBody(body io.Reader, headers Headers, cte ContentTransferEncoding) (AttachedFile, error) {
+	var afl AttachedFile
+
+	decoded, err := decodeContent(body, nil, cte)
+	if err != nil {
+		return afl, fmt.Errorf(
+			"letters.decoders.decodeAttachmentFileFromBody: cannot decode attached file content: %w",
+			err)
+	}
+
+	afl.ContentType = headers.ContentType
+	afl.ContentDisposition = headers.ContentDisposition
+	afl.Data, err = ioutil.ReadAll(decoded)
+	if err != nil {
+		return afl, fmt.Errorf(
+			"letters.decoders.decodeAttachmentFileFromBody: cannot read attached file data: %w",
+			err)
+	}
+
+	return afl, nil
+}
+
+func decodeAttachedFileFromPart(part *multipart.Part, cte ContentTransferEncoding) (AttachedFile, error) {
 	var afl AttachedFile
 
 	decoded, err := decodeContent(part, nil, cte)
 	if err != nil {
 		return afl, fmt.Errorf(
-			"letters.decoders.decodeAttachedFile: cannot decode attached file content: %w",
+			"letters.decoders.decodeAttachedFileFromPart: cannot decode attached file content: %w",
 			err)
 	}
 
 	afl.ContentType, err = parseContentTypeHeader(part.Header.Get("Content-Type"))
 	if err != nil {
 		return afl, fmt.Errorf(
-			"letters.decoders.decodeAttachedFile: cannot parse Content-Type of attached file: %w",
+			"letters.decoders.decodeAttachedFileFromPart: cannot parse Content-Type of attached file: %w",
 			err)
 	}
 
 	afl.ContentDisposition, err = parseContentDisposition(part.Header.Get("Content-Disposition"))
 	if err != nil {
 		return afl, fmt.Errorf(
-			"letters.decoders.decodeAttachedFile: cannot parse Content-Disposition of attached file: %w",
+			"letters.decoders.decodeAttachedFileFromPart: cannot parse Content-Disposition of attached file: %w",
 			err)
 	}
 
 	afl.Data, err = ioutil.ReadAll(decoded)
 	if err != nil {
 		return afl, fmt.Errorf(
-			"letters.decoders.decodeAttachedFile: cannot read attached file data: %w",
+			"letters.decoders.decodeAttachedFileFromPart: cannot read attached file data: %w",
 			err)
 	}
 

letters.go

@@ -66,11 +66,13 @@ func ParseEmail(r io.Reader) (Email, error) {
 		email.AttachedFiles = emailBodies.AttachedFiles
 
 	} else {
-		return email, fmt.Errorf(
-			"letters.ParseEmail: cannot parse unknown Content-Type %q: %w",
-			email.Headers.ContentType.ContentType,
-			&UnknownContentTypeError{contentType: email.Headers.ContentType.ContentType},
-		)
+		afl, err := decodeAttachmentFileFromBody(msg.Body, email.Headers, cte)
+		if err != nil {
+			return email, fmt.Errorf(
+				"letters.decoders.ParseEmail: cannot decode attached file content from body: %w",
+				err)
+		}
+		email.AttachedFiles = append(email.AttachedFiles, afl)
 	}
 
 	email.Text = normalizeMultilineString(email.Text)

letters_test.go

@@ -46,6 +46,111 @@ defaults (e.g. text/plain Content-Type).`,
 	testEmailFromFile(t, fp, expectedEmail)
 }
 
+func TestParseEmailEnglishNoTextContent(t *testing.T) {
+	fp := "tests/test_english_no_text_content.txt"
+	tz, _ := time.LoadLocation("Europe/London")
+	expectedDate, _ := time.Parse(
+		time.RFC1123Z+" (MST)",
+		time.Date(2019, time.April, 1, 7, 55, 0, 0, tz).Format(time.RFC1123Z+" (MST)"))
+	expectedEmail := Email{
+		Headers: Headers{
+			Date:    expectedDate,
+			Subject: "Test No Text Content, Attachment Only",
+			ReplyTo: []*mail.Address{
+				{
+					Name:    "Alice Sender",
+					Address: "alice.sender@example.net",
+				},
+			},
+			Sender: &mail.Address{
+				Name:    "Alice Sender",
+				Address: "alice.sender@example.com",
+			},
+			From: []*mail.Address{
+				{
+					Name:    "Alice Sender",
+					Address: "alice.sender@example.com",
+				},
+				{
+					Name:    "Alice Sender",
+					Address: "alice.sender@example.net",
+				},
+			},
+			To: []*mail.Address{
+				{
+					Name:    "Bob Recipient",
+					Address: "bob.recipient@example.com",
+				},
+				{
+					Name:    "Carol Recipient",
+					Address: "carol.recipient@example.com",
+				},
+			},
+			Cc: []*mail.Address{
+				{
+					Name:    "Dan Recipient",
+					Address: "dan.recipient@example.com",
+				},
+				{
+					Name:    "Eve Recipient",
+					Address: "eve.recipient@example.com",
+				},
+			},
+			Bcc: []*mail.Address{
+				{
+					Name:    "Frank Recipient",
+					Address: "frank.recipient@example.com",
+				},
+				{
+					Name:    "Grace Recipient",
+					Address: "grace.recipient@example.com",
+				},
+			},
+			MessageID: "Message-Id-1@example.com",
+			ContentType: ContentTypeHeader{
+				ContentType: "application/pdf",
+				Params: map[string]string{
+					"name": "attached-pdf-name.pdf",
+				},
+			},
+			ContentDisposition: ContentDispositionHeader{
+				ContentDisposition: attachment,
+				Params: map[string]string{
+					"filename": "attached-pdf-filename.pdf",
+				},
+			},
+			ExtraHeaders: map[string][]string{
+				"X-Clacks-Overhead": {"GNU Terry Pratchett"},
+			},
+		},
+		Text:         "",
+		EnrichedText: "",
+		HTML:         "",
+		AttachedFiles: []AttachedFile{
+			{
+				ContentType: ContentTypeHeader{
+					ContentType: "application/pdf",
+					Params: map[string]string{
+						"name": "attached-pdf-name.pdf",
+					},
+				},
+				ContentDisposition: ContentDispositionHeader{
+					ContentDisposition: attachment,
+					Params: map[string]string{
+						"filename": "attached-pdf-filename.pdf",
+					},
+				},
+				Data: []byte{37, 80, 68, 70, 45, 49, 46, 13, 116, 114, 97, 105, 108, 101, 114, 60, 60,
+					47, 82, 111, 111, 116, 60, 60, 47, 80, 97, 103, 101, 115, 60, 60, 47, 75, 105, 100, 115, 91, 60,
+					60, 47, 77, 101, 100, 105, 97, 66, 111, 120, 91, 48, 32, 48, 32, 51, 32, 51, 93, 62, 62, 93, 62,
+					62, 62, 62, 62, 62},
+			},
+		},
+	}
+
+	testEmailFromFile(t, fp, expectedEmail)
+}
+
 func TestParseEmailEnglishPlaintextAsciiOver7bit(t *testing.T) {
 	fp := "tests/test_english_plaintext_ascii_over_7bit.txt"
 	tz, _ := time.LoadLocation("Europe/London")

parsers.go

@@ -231,6 +231,8 @@ func parseHeaders(header mail.Header) (Headers, error) {
 			err)
 	}
 
+	contentDisposition, _ := parseContentDisposition(header.Get("Content-Disposition"))
+
 	var extraHeaders = make(map[string][]string)
 	for key, value := range header {
 		_, isKnownHeader := knownHeaders[key]
@@ -322,28 +324,29 @@ func parseHeaders(header mail.Header) (Headers, error) {
 	}
 
 	return Headers{
-		Date:            parseDateHeader(header.Get("Date")),
-		Sender:          sender,
-		From:            from,
-		ReplyTo:         replyTo,
-		To:              to,
-		Cc:              cc,
-		Bcc:             bcc,
-		MessageID:       parseMessageIdHeader(header.Get("Message-ID")),
-		InReplyTo:       parseCommaSeparatedMessageIdHeader(header.Get("In-Reply-To")),
-		References:      parseCommaSeparatedMessageIdHeader(header.Get("References")),
-		Subject:         parseStringHeader(header.Get("Subject")),
-		Comments:        parseStringHeader(header.Get("Comments")),
-		Keywords:        parseCommaSeparatedStringHeader(header.Get("Keywords")),
-		ResentDate:      parseDateHeader(header.Get("Resent-Date")),
-		ResentFrom:      resentFrom,
-		ResentSender:    resentSender,
-		ResentTo:        resentTo,
-		ResentCc:        resentCc,
-		ResentBcc:       resentBcc,
-		ResentMessageID: parseMessageIdHeader(header.Get("Resent-Message-ID")),
-		ContentType:     contentType,
-		ExtraHeaders:    extraHeaders,
+		Date:               parseDateHeader(header.Get("Date")),
+		Sender:             sender,
+		From:               from,
+		ReplyTo:            replyTo,
+		To:                 to,
+		Cc:                 cc,
+		Bcc:                bcc,
+		MessageID:          parseMessageIdHeader(header.Get("Message-ID")),
+		InReplyTo:          parseCommaSeparatedMessageIdHeader(header.Get("In-Reply-To")),
+		References:         parseCommaSeparatedMessageIdHeader(header.Get("References")),
+		Subject:            parseStringHeader(header.Get("Subject")),
+		Comments:           parseStringHeader(header.Get("Comments")),
+		Keywords:           parseCommaSeparatedStringHeader(header.Get("Keywords")),
+		ResentDate:         parseDateHeader(header.Get("Resent-Date")),
+		ResentFrom:         resentFrom,
+		ResentSender:       resentSender,
+		ResentTo:           resentTo,
+		ResentCc:           resentCc,
+		ResentBcc:          resentBcc,
+		ResentMessageID:    parseMessageIdHeader(header.Get("Resent-Message-ID")),
+		ContentType:        contentType,
+		ContentDisposition: contentDisposition,
+		ExtraHeaders:       extraHeaders,
 	}, nil
 }
 
@@ -500,7 +503,7 @@ func parsePart(msg io.Reader, parentContentType ContentTypeHeader, boundary stri
 				}
 				emailBodies.InlineFiles = append(emailBodies.InlineFiles, inlineFile)
 			} else if isAttFile {
-				attachedFile, err := decodeAttachedFile(part, cte)
+				attachedFile, err := decodeAttachedFileFromPart(part, cte)
 				if err != nil {
 					return emailBodies, fmt.Errorf(
 						"letters.parsers.parsePart: cannot decode attached file: %w",

structs.go

@@ -35,6 +35,7 @@ var knownHeaders = map[string]void{
 	"Resent-Message-Id":         member,
 	"Content-Transfer-Encoding": member,
 	"Content-Type":              member,
+	"Content-Disposition":       member,
 }
 
 type ContentDisposition string
@@ -525,8 +526,9 @@ type Headers struct {
 	// If another top-level type is to be used for any reason, it must be
 	// given a name starting with "X-" to indicate its non-standard status
 	// and to avoid a potential conflict with a future official name.
-	ContentType  ContentTypeHeader
-	ExtraHeaders map[string][]string
+	ContentType        ContentTypeHeader
+	ContentDisposition ContentDispositionHeader
+	ExtraHeaders       map[string][]string
 }
 
 type emailBodies struct {

tests/test_english_no_text_content.txt

@@ -0,0 +1,20 @@
+Date: Mon, 01 Apr 2019 07:55:00 +0100 (BST)
+From: =?uTf-8?b?QWxpY2UgU2VuZGVy?= <alice.sender@example.com>,
+ =?uTf-8?b?QWxpY2UgU2VuZGVy?= <alice.sender@example.net>
+Sender: =?uTf-8?b?QWxpY2UgU2VuZGVy?= <alice.sender@example.com>
+Reply-To: =?uTf-8?b?QWxpY2UgU2VuZGVy?= <alice.sender@example.net>
+To: =?utf-8?b?Qm9iIFJlY2lwaWVudA==?= <bob.recipient@example.com>,
+ =?UTF-8?B?Q2Fyb2wgUmVjaXBpZW50?= <carol.recipient@example.com>
+Cc: =?Utf-8?B?RGFuIFJlY2lwaWVudA==?= <dan.recipient@example.com>,
+ =?uTF-8?b?RXZlIFJlY2lwaWVudA==?= <eve.recipient@example.com>
+Bcc: =?utf-8?b?RnJhbmsgUmVjaXBpZW50?= <frank.recipient@example.com>,
+ =?Utf-8?B?R3JhY2UgUmVjaXBpZW50?= <grace.recipient@example.com>
+Message-ID: <Message-Id-1@example.com>
+Subject: Test No Text Content, Attachment Only
+Content-Type: applicaTION/PDF; NAME="attached-pdf-name.pdf"
+Content-Disposition: AttachmenT; FILENAMe="attached-pdf-filename.pdf"
+Content-Transfer-Encoding: BASE64
+X-Clacks-Overhead: GNU Terry Pratchett
+
+JVBERi0xLg10cmFpbGVyPDwvUm9vdDw8L1BhZ2VzPDwvS2lkc1s8PC9NZWRpYUJveFswIDAgMyAz
+XT4+XT4+Pj4+Pg==