Close XSS issue in /base64 endpoint (fixes #67) (#68)

httpbin/handlers.go

@@ -982,7 +982,7 @@ func (h *HTTPBin) Base64(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, fmt.Sprintf("%s failed: %s", b.operation, base64Error), http.StatusBadRequest)
 		return
 	}
-	writeResponse(w, http.StatusOK, "text/html", result)
+	writeResponse(w, http.StatusOK, "text/plain", result)
 }
 
 // JSON - returns a sample json

httpbin/handlers_test.go

@@ -2425,6 +2425,7 @@ func TestBase64(t *testing.T) {
 			w := httptest.NewRecorder()
 			handler.ServeHTTP(w, r)
 			assertStatusCode(t, w, http.StatusOK)
+			assertContentType(t, w, "text/plain")
 			assertBodyEquals(t, w, test.want)
 		})
 	}