Fix media URL extension for m4a uploads

server/media/media.go

@@ -4,6 +4,7 @@ package media
 import (
 	"errors"
 	"io"
+	"mime"
 	"net/http"
 	"net/url"
 	"path"
@@ -68,6 +69,37 @@ type AllowedOrigin struct {
 
 var fileNamePattern = regexp.MustCompile(`^[-_A-Za-z0-9]+`)
 
+// ExtensionByMimeType returns a stable URL extension for uploaded media.
+func ExtensionByMimeType(mimeType string) string {
+	switch strings.ToLower(strings.TrimSpace(strings.Split(mimeType, ";")[0])) {
+	case "audio/x-m4a", "audio/m4a", "audio/mp4", "audio/mp4a-latm":
+		return ".m4a"
+	case "audio/aac", "audio/aacp":
+		return ".aac"
+	case "audio/mpeg", "audio/mp3":
+		return ".mp3"
+	case "audio/ogg":
+		return ".ogg"
+	case "audio/wav", "audio/x-wav", "audio/wave":
+		return ".wav"
+	case "audio/webm":
+		return ".webm"
+	case "image/pjpeg", "image/jpg":
+		return ".jpg"
+	case "image/jpeg":
+		return ".jpg"
+	case "image/jfif":
+		return ".jfif"
+	case "video/mp4":
+		return ".mp4"
+	}
+	exts, _ := mime.ExtensionsByType(mimeType)
+	if len(exts) > 0 {
+		return exts[0]
+	}
+	return ""
+}
+
 // GetIdFromUrl is a helper method for extracting file ID from a URL.
 func GetIdFromUrl(url, serveUrl string) types.Uid {
 	dir, fname := path.Split(path.Clean(url))