Googstr/public/bunker.js

// NIP-46 remote signer ("bunker") running inside this tab.
//
// Other nostr apps talk to us over relays with kind-24133 events, encrypted
// with NIP-44 (NIP-04 accepted from older clients). We use the user's own key
// as the remote-signer key, so bunker://<user pubkey>.
//
// Pairing:
//   * bunker:// link — we mint a one-time secret; the first client to send
//     `connect` with it becomes authorized.
//   * nostrconnect:// link — the app shows it; we authorize that client and
//     reply to `connect` with its secret, per the spec.
// Authorized clients are remembered per identity in localStorage (only their
// pubkeys and names; no secrets). Pending bunker secrets live in
// sessionStorage and die with the tab.
//
// ponytail: authorized clients get every method without per-request prompts,
// like NIP-07 "always allow". Add per-kind approval if users ask for it.

const KIND = 24133;
const LOG_MAX = 30;

const load = (store, key, fallback) => {
  try { return JSON.parse(store.getItem(key)) ?? fallback; } catch { return fallback; }
};
const save = (store, key, value) => {
  try { store.setItem(key, JSON.stringify(value)); } catch {}
};
const randomHex = (n) => [...crypto.getRandomValues(new Uint8Array(n))].map((b) => b.toString(16).padStart(2, "0")).join("");

export function createBunker({ signer, pool, relays, onChange = () => {} }) {
  const clientsKey = `goostr.bunker.clients.${signer.pubkey}`;
  const secretsKey = `goostr.bunker.secrets.${signer.pubkey}`;
  const clients = load(localStorage, clientsKey, {}); // pubkey -> { name, addedAt, lastSeen }
  const log = [];
  const handled = new Set();
  let unsub = null;

  const persist = () => { save(localStorage, clientsKey, clients); onChange(); };
  const note = (entry) => {
    log.unshift({ t: Date.now(), ...entry });
    if (log.length > LOG_MAX) log.pop();
    onChange();
  };

  async function reply(clientPk, scheme, payload) {
    const plain = JSON.stringify(payload);
    const content = scheme === "nip04"
      ? await signer.nip04.encrypt(clientPk, plain)
      : await signer.nip44.encrypt(clientPk, plain);
    pool.publish(signer.sign({ kind: KIND, content, tags: [["p", clientPk]] }));
  }

  async function run(method, params, clientPk) {
    switch (method) {
      case "connect": {
        if (clients[clientPk]) return "ack";
        const secret = params[1];
        const pending = load(sessionStorage, secretsKey, []);
        if (!secret || !pending.includes(secret)) throw new Error("unauthorized: invalid or already used connection secret");
        save(sessionStorage, secretsKey, pending.filter((s) => s !== secret));
        clients[clientPk] = { name: `App ${clientPk.slice(0, 8)}`, addedAt: Date.now(), lastSeen: Date.now() };
        persist();
        return "ack";
      }
      case "ping":
        return "pong";
      case "get_public_key":
        return signer.pubkey;
      case "sign_event": {
        const ev = JSON.parse(params[0]);
        if (!Number.isInteger(ev.kind)) throw new Error("sign_event: missing kind");
        return JSON.stringify(signer.sign(ev));
      }
      case "nip04_encrypt": return signer.nip04.encrypt(params[0], params[1]);
      case "nip04_decrypt": return signer.nip04.decrypt(params[0], params[1]);
      case "nip44_encrypt": return signer.nip44.encrypt(params[0], params[1]);
      case "nip44_decrypt": return signer.nip44.decrypt(params[0], params[1]);
      case "logout":
        delete clients[clientPk];
        persist();
        return "ack";
      default:
        throw new Error(`unsupported method: ${method}`);
    }
  }

  async function handle(ev) {
    if (handled.has(ev.id)) return;
    handled.add(ev.id);
    if (ev.kind !== KIND) return; // signature already checked by the pool
    const clientPk = ev.pubkey;

    const scheme = ev.content.includes("?iv=") ? "nip04" : "nip44";
    let req;
    try {
      const plain = scheme === "nip04"
        ? await signer.nip04.decrypt(clientPk, ev.content)
        : await signer.nip44.decrypt(clientPk, ev.content);
      req = JSON.parse(plain);
    } catch {
      return; // not for us, or garbage
    }
    if (!req?.id || !req.method) return;
    const params = Array.isArray(req.params) ? req.params : [];

    const known = !!clients[clientPk];
    if (!known && req.method !== "connect") {
      // Unknown apps get an error rather than silence, so they can tell the
      // user to pair first. Nothing is signed or decrypted for them.
      await reply(clientPk, scheme, { id: req.id, error: "unauthorized: pair this app with Goostr first" });
      return;
    }

    const who = clients[clientPk]?.name || `App ${clientPk.slice(0, 8)}`;
    try {
      const result = await run(req.method, params, clientPk);
      await reply(clientPk, scheme, { id: req.id, result });
      if (clients[clientPk]) { clients[clientPk].lastSeen = Date.now(); persist(); }
      const detail = req.method === "sign_event" ? `kind ${safeKind(params[0])}` : "";
      note({ who, method: req.method, detail, ok: true });
    } catch (err) {
      await reply(clientPk, scheme, { id: req.id, error: String(err.message || err) });
      note({ who, method: req.method, detail: String(err.message || err), ok: false });
    }
  }

  return {
    get running() { return !!unsub; },
    get clients() { return clients; },
    get log() { return log; },

    start() {
      if (unsub) return;
      unsub = pool.subscribe(
        [{ kinds: [KIND], "#p": [signer.pubkey], since: Math.floor(Date.now() / 1000) - 60 }],
        (ev) => { handle(ev).catch((e) => console.warn("[bunker]", e)); }
      );
      onChange();
    },

    stop() {
      unsub?.();
      unsub = null;
      onChange();
    },

    // One-time bunker:// link for pasting into another app.
    newBunkerUrl() {
      const secret = randomHex(16);
      save(sessionStorage, secretsKey, [...load(sessionStorage, secretsKey, []), secret]);
      const qs = relays.map((r) => `relay=${encodeURIComponent(r)}`).join("&");
      return `bunker://${signer.pubkey}?${qs}&secret=${secret}`;
    },

    // Accept a nostrconnect:// link shown by another app.
    async acceptNostrConnect(uri) {
      const u = new URL(uri.trim());
      if (u.protocol !== "nostrconnect:") throw new Error("That isn't a nostrconnect:// link.");
      const clientPk = (u.hostname || u.pathname.replace(/^\/+/, "")).toLowerCase();
      if (!/^[0-9a-f]{64}$/.test(clientPk)) throw new Error("The link has no valid app public key.");
      const secret = u.searchParams.get("secret");
      if (!secret) throw new Error("The link has no secret; the app may use an old NIP-46 version.");
      const linkRelays = u.searchParams.getAll("relay");
      if (!linkRelays.length) throw new Error("The link names no relays.");
      linkRelays.forEach((r) => pool.addRelay(r));

      clients[clientPk] = {
        name: u.searchParams.get("name") || `App ${clientPk.slice(0, 8)}`,
        addedAt: Date.now(),
        lastSeen: Date.now(),
      };
      persist();
      this.start();
      await reply(clientPk, "nip44", { id: randomHex(8), result: secret });
      note({ who: clients[clientPk].name, method: "connect", detail: "via nostrconnect link", ok: true });
    },

    rename(clientPk, name) {
      if (!clients[clientPk]) return;
      clients[clientPk].name = name;
      persist();
    },

    revoke(clientPk) {
      delete clients[clientPk];
      persist();
    },
  };
}

function safeKind(json) {
  try { return JSON.parse(json).kind; } catch { return "?"; }
}