feat: browser client for smol mail

web/js/transport.js

@@ -0,0 +1,22 @@
+// The byte pipe to a smolmaild server. Browsers cannot open TCP sockets, so
+// bytes travel through the local bridge's WebSocket relay unchanged; the
+// Noise session lives in this page either way.
+
+const BRIDGE = `${location.protocol === "https:" ? "wss" : "ws"}://${location.host}`;
+
+export function connectStream(host, port) {
+  return new Promise((resolve, reject) => {
+    const socket = new WebSocket(`${BRIDGE}/tcp/${host}/${port}`);
+    socket.binaryType = "arraybuffer";
+    const stream = {
+      send: bytes => socket.send(bytes),
+      close: () => socket.close(),
+      onData: null,
+      onClose: null,
+    };
+    socket.onopen = () => resolve(stream);
+    socket.onerror = () => reject(new Error(`cannot reach the bridge at ${BRIDGE}`));
+    socket.onmessage = event => stream.onData?.(new Uint8Array(event.data));
+    socket.onclose = () => stream.onClose?.();
+  });
+}