Fixed improper implementation of content type (#501)

* Fixed improper implementation of content type

Add text/plain content type if metadata.ContentType is unable to determine the content type of the file

* Update server/handlers.go

Co-authored-by: Farhan Khursheed <41877347+blind-intruder@users.noreply.github.com>

* Update handlers.go

let's trim space

* Update handlers.go

Co-authored-by: Andrea Spacca <andrea.spacca@gmail.com>

server/handlers.go

@@ -1034,6 +1034,13 @@ func (s *Server) getHandler(w http.ResponseWriter, r *http.Request) {
 
 	if action == "inline" {
 		disposition = "inline"
+		/*
+		metadata.ContentType is unable to determine the type of the content, 
+		So add text/plain in this case to fix XSS related issues/
+		*/
+		if strings.TrimSpace(contentType) == "" {
+		      contentType = "text/plain"
+		 }
 	} else {
 		disposition = "attachment"
 	}