[ISSUE-41] Modify parsers.go to parse Content Disposition header in p…

…arsePart() to correctly handle attachments of any content type. Simplify parsePart() loop. Simplify isInlineFile() and isAttachedFile() to not parse Content Disposition header multiple times.
mnako · Aug 13, 2023 · 13b2791 · 13b2791
1 parent baed02e
commit 13b2791
Showing 1 changed file with 48 additions and 50 deletions.
diff --git a/parsers.go b/parsers.go
@@ -368,36 +368,21 @@ func parseText(t io.Reader, e encoding.Encoding, cte ContentTransferEncoding) (s
 	return strings.TrimSuffix(string(textBody), "\n"), nil
 }
 
-func isInlineFile(contentType ContentTypeHeader, parentContentType ContentTypeHeader, p *multipart.Part) (bool, error) {
-	cdh, err := parseContentDisposition(p.Header.Get("Content-Disposition"))
-	if err != nil {
-		return false, fmt.Errorf(
-			"letters.parsers.isInlineFile: cannot parse Content-Disposition: %w",
-			err)
-	}
+func isInlineFile(contentType ContentTypeHeader, parentContentType ContentTypeHeader, cdh ContentDispositionHeader) bool {
 	if cdh.ContentDisposition == inline {
-		return true, nil
+		return true
 	}
 	if contentType.ContentType == contentTypeTextPlain || contentType.ContentType == contentTypeTextEnriched || contentType.ContentType == contentTypeTextHtml {
-		return false, nil
+		return false
 	}
-	return parentContentType.ContentType == contentTypeMultipartRelated, nil
+	return parentContentType.ContentType == contentTypeMultipartRelated
 }
 
-func isAttachedFile(contentType ContentTypeHeader, parentContentType ContentTypeHeader, part *multipart.Part) (bool, error) {
-	cdh, err := parseContentDisposition(part.Header.Get("Content-Disposition"))
-	if err != nil {
-		return false, fmt.Errorf(
-			"letters.parsers.isAttachedFile: cannot parse Content-Disposition: %w",
-			err)
-	}
-	if cdh.ContentDisposition == attachment {
-		return true, nil
-	}
+func isAttachedFile(contentType ContentTypeHeader, parentContentType ContentTypeHeader) bool {
 	if contentType.ContentType != contentTypeTextPlain && contentType.ContentType != contentTypeTextEnriched && contentType.ContentType != contentTypeTextHtml {
-		return true, nil
+		return true
 	}
-	return parentContentType.ContentType == contentTypeMultipartMixed || parentContentType.ContentType == contentTypeMultipartParallel, nil
+	return parentContentType.ContentType == contentTypeMultipartMixed || parentContentType.ContentType == contentTypeMultipartParallel
 }
 
 func parsePart(msg io.Reader, parentContentType ContentTypeHeader, boundary string) (emailBodies, error) {
@@ -441,6 +426,23 @@ func parsePart(msg io.Reader, parentContentType ContentTypeHeader, boundary stri
 				err)
 		}
 
+		cdh, err := parseContentDisposition(part.Header.Get("Content-Disposition"))
+		if err != nil {
+			return emailBodies, fmt.Errorf(
+				"letters.parsers.parsePart: cannot parse Content-Disposition: %w",
+				err)
+		}
+		if cdh.ContentDisposition == attachment {
+			attachedFile, err := decodeAttachedFileFromPart(part, cte)
+			if err != nil {
+				return emailBodies, fmt.Errorf(
+					"letters.parsers.parsePart: cannot decode attached file: %w",
+					err)
+			}
+			emailBodies.AttachedFiles = append(emailBodies.AttachedFiles, attachedFile)
+			continue
+		}
+
 		if partContentType.ContentType == contentTypeTextPlain {
 			partTextBody, err := parseText(part, enc, cte)
 			if err != nil {
@@ -450,26 +452,32 @@ func parsePart(msg io.Reader, parentContentType ContentTypeHeader, boundary stri
 			}
 			emailBodies.text += partTextBody
 			emailBodies.text += "\n\n"
+			continue
+		}
 
-		} else if partContentType.ContentType == contentTypeTextEnriched {
+		if partContentType.ContentType == contentTypeTextEnriched {
 			partEnrichedText, err := parseText(part, enc, cte)
 			if err != nil {
 				return emailBodies, fmt.Errorf(
 					"letters.parsers.parsePart: cannot parse enriched text: %w",
 					err)
 			}
 			emailBodies.enrichedText += partEnrichedText
+			continue
+		}
 
-		} else if partContentType.ContentType == contentTypeTextHtml {
+		if partContentType.ContentType == contentTypeTextHtml {
 			partHtmlBody, err := parseText(part, enc, cte)
 			if err != nil {
 				return emailBodies, fmt.Errorf(
 					"letters.parsers.parsePart: cannot parse html text: %w",
 					err)
 			}
 			emailBodies.html += partHtmlBody
+			continue
+		}
 
-		} else if strings.HasPrefix(partContentType.ContentType, contentTypeMultipartPrefix) {
+		if strings.HasPrefix(partContentType.ContentType, contentTypeMultipartPrefix) {
 			nestedEmailBodies, err := parsePart(part, partContentType, partContentType.Params["boundary"])
 			if err != nil {
 				return emailBodies, fmt.Errorf(
@@ -478,42 +486,32 @@ func parsePart(msg io.Reader, parentContentType ContentTypeHeader, boundary stri
 			}
 
 			emailBodies.extend(nestedEmailBodies)
-		} else {
+			continue
+		}
 
-			isInlFile, err := isInlineFile(partContentType, parentContentType, part)
+		if isInlineFile(partContentType, parentContentType, cdh) {
+			inlineFile, err := decodeInlineFile(part, cte)
 			if err != nil {
 				return emailBodies, fmt.Errorf(
-					"letters.parsers.parsePart: cannot read part: %w",
+					"letters.parsers.parsePart: cannot decode inline file: %w",
 					err)
 			}
+			emailBodies.InlineFiles = append(emailBodies.InlineFiles, inlineFile)
+			continue
+		}
 
-			isAttFile, err := isAttachedFile(partContentType, parentContentType, part)
+		if isAttachedFile(partContentType, parentContentType) {
+			attachedFile, err := decodeAttachedFileFromPart(part, cte)
 			if err != nil {
 				return emailBodies, fmt.Errorf(
-					"letters.parsers.parsePart: cannot check attached file: %w",
+					"letters.parsers.parsePart: cannot decode attached file: %w",
 					err)
 			}
-
-			if isInlFile {
-				inlineFile, err := decodeInlineFile(part, cte)
-				if err != nil {
-					return emailBodies, fmt.Errorf(
-						"letters.parsers.parsePart: cannot decode inline file: %w",
-						err)
-				}
-				emailBodies.InlineFiles = append(emailBodies.InlineFiles, inlineFile)
-			} else if isAttFile {
-				attachedFile, err := decodeAttachedFileFromPart(part, cte)
-				if err != nil {
-					return emailBodies, fmt.Errorf(
-						"letters.parsers.parsePart: cannot decode attached file: %w",
-						err)
-				}
-				emailBodies.AttachedFiles = append(emailBodies.AttachedFiles, attachedFile)
-			} else {
-				return emailBodies, &UnknownContentTypeError{contentType: parentContentType.ContentType}
-			}
+			emailBodies.AttachedFiles = append(emailBodies.AttachedFiles, attachedFile)
+			continue
 		}
+
+		return emailBodies, &UnknownContentTypeError{contentType: parentContentType.ContentType}
 	}
 
 	emailBodies.text = strings.Trim(emailBodies.text, "\n")