add client receiving base

client/tools.ts

@@ -0,0 +1,13 @@
+/**
+ * Convert big-endian u32 to native JavaScript number.
+ */
+export function uint_bytes_to_num(value: Uint8Array): number {
+	if (value.length != 4) { throw new Error("can't convert non 4-byte integer"); }
+	const data_view = new DataView(value.buffer);
+	return data_view.getUint32(0, false);
+}
+
+export function utf8_decode(value: Uint8Array): string {
+	const decoder = new TextDecoder("utf-8");
+	return decoder.decode(value);
+}