pithos/web/lib/hosted.js

// The browser app's client for Drives on Silent Mode. It is served from the
// gateway's own origin, so every call here is same-origin: sign-in and the
// account API under /hosted/v1 and /api, S3 at /<drive>/<key>. Names and
// contents are encrypted and decrypted here exactly as core/hosted.js does.

import * as C from './crypt.js';
import { sign, presign, objectPath, canonicalQuery } from './sigv4.js';

const subtle = globalThis.crypto.subtle;
const b64 = (bytes) => btoa(String.fromCharCode(...bytes));
const unb64 = (s) => Uint8Array.from(atob(String(s || '')), (c) => c.charCodeAt(0));
const hex = (b) => Array.from(b, (x) => x.toString(16).padStart(2, '0')).join('');
const PKCS8_ED25519 = Uint8Array.from([0x30, 0x2e, 0x02, 0x01, 0x00, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x65, 0x70, 0x04, 0x22, 0x04, 0x20]);

export class ApiError extends Error {
  constructor(status, message, data) { super(message); this.status = status; this.data = data; }
}

// ---- key files -----------------------------------------------------------------------

// What a dropped or pasted file is: an owner key (Pithos key file, v1 secret or
// v2 browser key) or an S3 key ({endpoint, accessKey, secretKey, bucket}).
export async function readKeyFile(text) {
  let o;
  try { o = typeof text === 'string' ? JSON.parse(text) : text; } catch { throw new Error('This is not a key file (it is not JSON).'); }
  if (o && o.secret && (o.v === 1 || o.v == null)) {
    const secret = unb64(o.secret);
    if (secret.length !== 32) throw new Error('This Pithos key file is damaged.');
    return {
      kind: 'owner',
      identitySeed: await C.hkdf(secret, new Uint8Array(0), 'pithos/hosted-identity/v1', 32),
      encryptionKey: await C.hkdf(secret, new Uint8Array(0), 'pithos/hosted-encryption/v1', 32),
    };
  }
  if (o && o.v === 2 && o.identitySeed && o.encryptionKey) {
    const identitySeed = unb64(o.identitySeed);
    const encryptionKey = unb64(o.encryptionKey);
    if (identitySeed.length !== 32 || encryptionKey.length !== 32) throw new Error('This browser key file is damaged.');
    return { kind: 'owner', identitySeed, encryptionKey };
  }
  if (o && o.accessKey && o.secretKey) {
    return { kind: 's3', accessKeyId: String(o.accessKey), secretKey: String(o.secretKey), bucket: o.bucket ? String(o.bucket) : '', endpoint: o.endpoint ? String(o.endpoint) : '' };
  }
  throw new Error('This file is neither a Pithos key nor an S3 key (Export JSON) file.');
}

// ---- the gateway's account API -----------------------------------------------------------

export async function api(method, path, { token, body } = {}) {
  const headers = {};
  if (token) headers.authorization = `Bearer ${token}`;
  if (body !== undefined) headers['content-type'] = 'application/json';
  const res = await fetch(path, { method, headers, body: body === undefined ? undefined : JSON.stringify(body), cache: 'no-store' });
  const text = await res.text();
  let data = null;
  try { data = text ? JSON.parse(text) : null; } catch { data = { error: text.slice(0, 300) }; }
  if (!res.ok) throw new ApiError(res.status, data?.error || `HTTP ${res.status}`, data);
  return data;
}

async function identity(seed) {
  const key = await subtle.importKey('pkcs8', C.concat(PKCS8_ED25519, seed), { name: 'Ed25519' }, true, ['sign']);
  const jwk = await subtle.exportKey('jwk', key);
  const pub = C.unb64u(jwk.x);
  return { pubkey: hex(pub), sign: async (msg) => b64(new Uint8Array(await subtle.sign('Ed25519', key, C.utf8(msg)))) };
}

// Ed25519 sign-in. Returns { token, id, state }; accounts are made in Pithos.
export async function signIn(identitySeed) {
  const id = await identity(identitySeed);
  const { nonce, message } = await api('GET', '/hosted/v1/challenge');
  try {
    return await api('POST', '/hosted/v1/session', { body: { pubkey: id.pubkey, nonce, signature: await id.sign(message) } });
  } catch (e) {
    if (e.status === 404 && e.data?.needsSignup) throw new Error('There is no account on Silent Mode for this key yet. Create it in Pithos (Accounts › On Silent Mode), then sign in here.');
    throw e;
  }
}

export const signOut = (token) => api('DELETE', '/hosted/v1/session', { token }).catch(() => {});

// The owner's S3 key: the first key of the first S3 user, as Pithos does.
export async function ownerS3(token) {
  const users = await api('GET', '/api/users', { token });
  const names = (Array.isArray(users) ? users : users?.users || []).map((u) => u.name || u.username || u).filter(Boolean);
  for (const user of names) {
    const keys = await api('GET', `/api/keys?user=${encodeURIComponent(user)}`, { token });
    if (keys?.length) return { user, accessKeyId: keys[0].accessKeyId, secretKey: keys[0].secretKey };
  }
  throw new Error('This account has no S3 keys yet. Create one in Pithos (Users & keys).');
}

// ---- S3, signed in the page ---------------------------------------------------------------

const xmlTag = (el, name) => el.getElementsByTagName(name)[0]?.textContent ?? '';
const xmlAll = (doc, name) => Array.from(doc.getElementsByTagName(name));
const parseXml = (text) => new DOMParser().parseFromString(text, 'application/xml');

async function s3Fail(res) {
  const text = await res.text().catch(() => '');
  let msg = `HTTP ${res.status}`;
  try { const d = parseXml(text); msg = xmlTag(d, 'Message') || xmlTag(d, 'Code') || msg; } catch {}
  try { const j = JSON.parse(text); msg = j.error || msg; } catch {}
  return new ApiError(res.status, msg);
}

// A drive client. master: the 32-byte encryption key (null for an S3 key file,
// which reads and writes readable files only). rules: async () => sharing rules.
export class Drives {
  constructor({ accessKeyId, secretKey, master = null, rules = async () => [] }) {
    this.creds = { host: location.host, origin: location.origin, accessKeyId, secretKey };
    this.master = master;
    this.rules = rules;
    this.dks = new Map();
  }

  async dk(bucket) {
    if (!this.master) return null;
    if (!this.dks.has(bucket)) this.dks.set(bucket, await C.driveKeys(this.master, bucket));
    return this.dks.get(bucket);
  }

  async req(method, path, { query = {}, headers = {}, body, ok = true } = {}) {
    const h = await sign(this.creds, method, path, query, headers);
    const qs = canonicalQuery(query);
    const res = await fetch(path + (qs ? '?' + qs : ''), { method, headers: h, body, cache: 'no-store' });
    if (ok && !res.ok) throw await s3Fail(res);
    return res;
  }

  async listBuckets() {
    const d = parseXml(await (await this.req('GET', '/')).text());
    return xmlAll(d, 'Bucket').map((b) => ({ name: xmlTag(b, 'Name'), created: xmlTag(b, 'CreationDate') }));
  }

  async rawList(bucket, { prefix = '', delimiter = '/', token, max = 1000 }) {
    const query = { 'list-type': '2', prefix, delimiter, 'max-keys': String(max) };
    if (token) query['continuation-token'] = token;
    const d = parseXml(await (await this.req('GET', objectPath(bucket), { query })).text());
    return {
      folders: xmlAll(d, 'CommonPrefixes').map((p) => xmlTag(p, 'Prefix')),
      objects: xmlAll(d, 'Contents').map((o) => ({ key: xmlTag(o, 'Key'), size: Number(xmlTag(o, 'Size')), modified: xmlTag(o, 'LastModified') })),
      truncated: xmlTag(d.documentElement, 'IsTruncated') === 'true',
      nextToken: xmlTag(d.documentElement, 'NextContinuationToken'),
    };
  }

  // One folder level, encrypted and readable names merged (core/hosted.js listObjects).
  async list(bucket, prefix = '') {
    const dk = await this.dk(bucket);
    const folders = new Map();
    const objects = new Map();
    const sources = dk && prefix ? [await C.encryptPath(dk, prefix), prefix] : [prefix];
    for (const pfx of sources) {
      let token;
      do {
        const page = await this.rawList(bucket, { prefix: pfx, token });
        for (const f of page.folders) {
          const d = dk ? await C.decryptPath(dk, f) : { path: f, encrypted: false };
          if (d.path.startsWith(prefix) && d.path !== prefix) folders.set(d.path, { path: d.path, encrypted: d.encrypted, locked: !dk && f.split('/').some((s) => s.startsWith('~')) });
        }
        for (const o of page.objects) {
          const d = dk ? await C.decryptPath(dk, o.key) : { path: o.key, encrypted: false };
          if (!d.path.startsWith(prefix) || d.path === prefix) continue;
          if (objects.has(d.path) && !d.encrypted) continue;
          const size = d.encrypted && !d.path.endsWith('/') ? C.plainSize(o.size) : o.size;
          objects.set(d.path, { key: d.path, size: size ?? o.size, modified: o.modified, encrypted: d.encrypted, storageKey: o.key, locked: !dk && o.key.split('/').some((s) => s.startsWith('~')) });
        }
        token = page.truncated ? page.nextToken : null;
      } while (token);
    }
    const order = (a, b) => (a < b ? -1 : a > b ? 1 : 0);
    return {
      folders: [...folders.values()].sort((a, b) => order(a.path, b.path)),
      files: [...objects.values()].filter((o) => !o.key.endsWith('/')).sort((a, b) => order(a.key, b.key)),
    };
  }

  async storeAsPlain(bucket, key) {
    if (!this.master) return true;
    const now = Date.now();
    return (await this.rules()).some((r) => r.bucket === bucket && (!r.expires || r.expires > now) && (r.type === 'link' ? r.prefix === key : key.startsWith(r.prefix)));
  }

  // Where a file lives: { encrypted, storageKey, size (plain) }.
  async locate(bucket, key) {
    const dk = await this.dk(bucket);
    if (dk) {
      const ek = await C.encryptPath(dk, key);
      const head = await this.req('HEAD', objectPath(bucket, ek), { ok: false });
      if (head.ok) {
        const total = Number(head.headers.get('content-length'));
        return { encrypted: true, storageKey: ek, cipherLen: total, size: C.plainSize(total) };
      }
    }
    const head = await this.req('HEAD', objectPath(bucket, key), { ok: false });
    if (!head.ok) throw new ApiError(head.status, head.status === 404 ? 'This file is gone.' : `HTTP ${head.status}`);
    return { encrypted: false, storageKey: key, size: Number(head.headers.get('content-length')) };
  }

  // Plaintext as a stream of Uint8Array chunks (whole file, or [start, end]).
  async *read(bucket, key, range) {
    const at = await this.locate(bucket, key);
    if (!at.encrypted) {
      const headers = range ? { range: `bytes=${range.start}-${range.end ?? ''}` } : {};
      const res = await this.req('GET', objectPath(bucket, at.storageKey), { headers });
      const reader = res.body.getReader();
      for (;;) { const { value, done } = await reader.read(); if (done) return; yield value; }
    }
    const dk = await this.dk(bucket);
    const r = C.cipherRange(at.cipherLen, range || null);
    if (r.unsatisfiable) return;
    const getBytes = async (from, to) => new Uint8Array(await (await this.req('GET', objectPath(bucket, at.storageKey), { headers: { range: `bytes=${from}-${to}` } })).arrayBuffer());
    const header = await getBytes(0, C.HEADER_LEN - 1);
    const ctx = await C.bodyContext(dk, key, header);
    const span = ctx.cs + C.TAG_LEN;
    // fetch a few chunks per request, open them one by one
    const BATCH = 8;
    let cache = { first: -1, bytes: null };
    const readChunk = async (i) => {
      if (i < cache.first || i >= cache.first + BATCH || !cache.bytes) {
        const from = C.HEADER_LEN + i * span;
        const to = Math.min(at.cipherLen - 1, from + BATCH * span - 1);
        cache = { first: i, bytes: await getBytes(from, to) };
      }
      const off = (i - cache.first) * span;
      return cache.bytes.subarray(off, Math.min(cache.bytes.length, off + span));
    };
    yield* C.decryptChunks(ctx, r, readChunk);
  }

  async blob(bucket, key, type) {
    const parts = [];
    for await (const p of this.read(bucket, key)) parts.push(p);
    return new Blob(parts, { type: type || guessType(key) });
  }

  // A link the page can hand to <audio>/<video>/<img> without decrypting:
  // only for readable files (encrypted ones go through blob()).
  presigned(bucket, storageKey, seconds = 3600) {
    return presign(this.creds, bucket, storageKey, seconds);
  }

  async write(bucket, key, file, onProgress = () => {}) {
    const dk = await this.dk(bucket);
    if (await this.storeAsPlain(bucket, key)) {
      await this.req('PUT', objectPath(bucket, key), { headers: { 'content-type': file.type || guessType(key) }, body: file });
      if (dk) { const ek = await C.encryptPath(dk, key); if (ek !== key) await this.req('DELETE', objectPath(bucket, ek), { ok: false }); }
      onProgress(file.size);
      return;
    }
    const ek = await C.encryptPath(dk, key);
    const parts = [];
    let done = 0;
    for await (const p of C.encryptBlob(dk, key, file)) { parts.push(p); done = Math.min(file.size, done + p.length); onProgress(done); }
    await this.req('PUT', objectPath(bucket, ek), { headers: { 'content-type': 'application/octet-stream' }, body: new Blob(parts) });
    if (ek !== key) await this.req('DELETE', objectPath(bucket, key), { ok: false });
  }

  async mkdir(bucket, folder) {
    const dk = await this.dk(bucket);
    const key = folder.endsWith('/') ? folder : folder + '/';
    const store = dk && !(await this.storeAsPlain(bucket, key)) ? await C.encryptPath(dk, key) : key;
    await this.req('PUT', objectPath(bucket, store), { body: new Uint8Array(0) });
  }

  async remove(bucket, key) {
    const dk = await this.dk(bucket);
    if (dk) await this.req('DELETE', objectPath(bucket, await C.encryptPath(dk, key)), { ok: false });
    await this.req('DELETE', objectPath(bucket, key), { ok: false });
  }

  async removeFolder(bucket, prefix, onEach = () => {}) {
    const all = [];
    const walk = async (p) => {
      const l = await this.list(bucket, p);
      for (const f of l.files) all.push(f);
      for (const d of l.folders) { await walk(d.path); all.push({ key: d.path, storageKey: null }); }
    };
    await walk(prefix);
    for (const f of all) { await this.remove(bucket, f.key); onEach(f.key); }
    await this.remove(bucket, prefix);
  }

  // Encrypted names and contents are bound to their path, so a rename is a
  // decrypt-and-encrypt copy here, then a delete.
  async rename(bucket, from, to) {
    if (from === to) return;
    const blob = await this.blob(bucket, from);
    await this.write(bucket, to, blob);
    await this.remove(bucket, from);
  }
}

const MIME = {
  html: 'text/html', htm: 'text/html', txt: 'text/plain', md: 'text/markdown', css: 'text/css', js: 'text/javascript', json: 'application/json',
  xml: 'application/xml', csv: 'text/csv', pdf: 'application/pdf', zip: 'application/zip', png: 'image/png', jpg: 'image/jpeg', jpeg: 'image/jpeg',
  gif: 'image/gif', webp: 'image/webp', svg: 'image/svg+xml', avif: 'image/avif', mp3: 'audio/mpeg', ogg: 'audio/ogg', oga: 'audio/ogg', wav: 'audio/wav',
  flac: 'audio/flac', m4a: 'audio/mp4', opus: 'audio/opus', mp4: 'video/mp4', webm: 'video/webm', mov: 'video/quicktime',
};
export const guessType = (key) => MIME[String(key).split('.').pop().toLowerCase()] || 'application/octet-stream';

// ---- remember on this device ------------------------------------------------------------------
// The key file, sealed with a passphrase (PBKDF2-SHA256 600k + AES-GCM), in
// IndexedDB on this origin. Nothing usable is stored without the passphrase.

const DB = 'pithos-web';
function idb() {
  return new Promise((resolve, reject) => {
    const r = indexedDB.open(DB, 1);
    r.onupgradeneeded = () => r.result.createObjectStore('kv');
    r.onsuccess = () => resolve(r.result);
    r.onerror = () => reject(r.error);
  });
}
async function kv(mode, fn) {
  const db = await idb();
  return new Promise((resolve, reject) => {
    const tx = db.transaction('kv', mode);
    const req = fn(tx.objectStore('kv'));
    tx.oncomplete = () => resolve(req?.result);
    tx.onerror = () => reject(tx.error);
  });
}
async function passKey(pass, salt) {
  const base = await subtle.importKey('raw', C.utf8(pass), 'PBKDF2', false, ['deriveKey']);
  return subtle.deriveKey({ name: 'PBKDF2', hash: 'SHA-256', salt, iterations: 600000 }, base, { name: 'AES-GCM', length: 256 }, false, ['encrypt', 'decrypt']);
}
export async function remember(keyText, pass) {
  const salt = crypto.getRandomValues(new Uint8Array(16));
  const iv = crypto.getRandomValues(new Uint8Array(12));
  const ct = new Uint8Array(await subtle.encrypt({ name: 'AES-GCM', iv }, await passKey(pass, salt), C.utf8(keyText)));
  await kv('readwrite', (s) => s.put({ v: 1, salt, iv, ct, saved: Date.now() }, 'key'));
}
export const remembered = () => kv('readonly', (s) => s.get('key')).catch(() => null);
export async function recall(pass) {
  const r = await remembered();
  if (!r) return null;
  try { return new TextDecoder().decode(await subtle.decrypt({ name: 'AES-GCM', iv: r.iv }, await passKey(pass, r.salt), r.ct)); } catch { throw new Error('Wrong passphrase.'); }
}
export const forget = () => kv('readwrite', (s) => s.delete('key')).catch(() => {});