Can specify MAC addresses for domains

virtweb_frontend/src/widgets/forms/MACInput.tsx

@@ -0,0 +1,46 @@
+import { TextInput } from "./TextInput";
+
+export function MACInput(p: {
+  label: string;
+  editable: boolean;
+  value?: string;
+  onValueChange?: (newVal: string | undefined) => void;
+}): React.ReactElement {
+  const { onValueChange, ...props } = p;
+  return (
+    <TextInput
+      onValueChange={(v) => {
+        onValueChange?.(sanitizeMacAddress(v));
+      }}
+      {...props}
+    />
+  );
+}
+
+function sanitizeMacAddress(s: string | undefined): string | undefined {
+  if (s === "" || s === undefined) return s;
+
+  const split = s.split(":");
+  if (split.length > 6) split.splice(6);
+
+  let needAnotherIteration = false;
+
+  const res = split
+    .map((e) => {
+      if (e === "") return e;
+
+      const num = parseInt(e, 16);
+      if (isNaN(num)) return "0";
+
+      let s = num.toString(16).padStart(2, "0");
+      if (num > 0xff) {
+        needAnotherIteration = true;
+        return s.slice(0, 2) + ":" + s.slice(2);
+      }
+
+      return s;
+    })
+    .join(":");
+
+  return needAnotherIteration ? sanitizeMacAddress(res) : res;
+}