[lightning] save node features as stringified json array in db

backend/src/utils/format.ts

@@ -26,4 +26,37 @@ export function formatBytes(bytes: number, toUnit: string, skipUnit = false): st
   }
 
   return `${bytes.toFixed(2)}${skipUnit ? '' : ' ' + byteUnits[unitIndex]}`;
+}
+
+// https://stackoverflow.com/a/64235212
+export function hex2bin(hex): string {
+  if (!hex) {
+    return '';
+  }
+
+  hex = hex.replace('0x', '').toLowerCase();
+  let out = '';
+
+  for (const c of hex) {
+    switch (c) {
+      case '0': out += '0000'; break;
+      case '1': out += '0001'; break;
+      case '2': out += '0010'; break;
+      case '3': out += '0011'; break;
+      case '4': out += '0100'; break;
+      case '5': out += '0101'; break;
+      case '6': out += '0110'; break;
+      case '7': out += '0111'; break;
+      case '8': out += '1000'; break;
+      case '9': out += '1001'; break;
+      case 'a': out += '1010'; break;
+      case 'b': out += '1011'; break;
+      case 'c': out += '1100'; break;
+      case 'd': out += '1101'; break;
+      case 'e': out += '1110'; break;
+      case 'f': out += '1111'; break;
+      default: return '';
+    }
+  }
+  return out;
 }