upstream-affine/packages/frontend/apps/electron/src/main/protocol.ts

import path, { join } from 'node:path';
import { pathToFileURL } from 'node:url';

import { app, net, protocol, session } from 'electron';

import { anotherHost, mainHost } from '../shared/internal-origin';
import {
  isPathInsideBase,
  isWindows,
  resolveExistingPathInBase,
  resolvePathInBase,
  resourcesPath,
} from '../shared/utils';
import {
  executeAuthSessionRequest,
  getAccessTokenForUrl,
  initializeAuthSessions,
  isManagedAuthEndpoint,
} from './auth/auth-session';
import { buildType, isDev } from './config';
import { logger } from './logger';

const webStaticDir = join(resourcesPath, 'web-static');
const devServerBase = process.env.DEV_SERVER_URL;
const localWhiteListDirs = [
  path.resolve(app.getPath('sessionData')),
  path.resolve(app.getPath('temp')),
];

function isPathInWhiteList(filepath: string) {
  return localWhiteListDirs.some(whitelistDir =>
    isPathInsideBase(whitelistDir, filepath, {
      caseInsensitive: isWindows(),
    })
  );
}

async function resolveWhitelistedLocalPath(filepath: string) {
  for (const whitelistDir of localWhiteListDirs) {
    try {
      return await resolveExistingPathInBase(whitelistDir, filepath, {
        caseInsensitive: isWindows(),
        label: 'filepath',
      });
    } catch {
      continue;
    }
  }

  throw new Error('Invalid filepath');
}

const apiBaseByBuildType: Record<typeof buildType, string> = {
  stable: 'https://app.affine.pro',
  beta: 'https://insider.affine.pro',
  internal: 'https://insider.affine.pro',
  canary: 'https://affine.fail',
};

function resolveApiBaseUrl() {
  if (isDev && devServerBase) {
    return devServerBase;
  }

  return apiBaseByBuildType[buildType] ?? apiBaseByBuildType.stable;
}

function buildTargetUrl(base: string, urlObject: URL) {
  return new URL(`${urlObject.pathname}${urlObject.search}`, base).toString();
}

async function proxyRequest(
  request: Request,
  urlObject: URL,
  base: string,
  options: { bypassCustomProtocolHandlers?: boolean } = {}
) {
  const { bypassCustomProtocolHandlers = true } = options;
  const targetUrl = buildTargetUrl(base, urlObject);
  return await executeAuthSessionRequest(request, targetUrl, request =>
    net.fetch(
      bypassCustomProtocolHandlers
        ? Object.assign(request, { bypassCustomProtocolHandlers: true })
        : request
    )
  );
}

async function handleFileRequest(request: Request) {
  const urlObject = new URL(request.url);

  if (urlObject.host === anotherHost) {
    urlObject.host = mainHost;
  }

  const isAbsolutePath = urlObject.host !== '.';
  const isApiRequest =
    !isAbsolutePath &&
    (urlObject.pathname.startsWith('/api/') ||
      urlObject.pathname === '/graphql');

  if (isApiRequest) {
    return proxyRequest(request, urlObject, resolveApiBaseUrl());
  }

  const isFontRequest =
    urlObject.pathname &&
    /\.(woff2?|ttf|otf)$/i.test(urlObject.pathname.split('?')[0] ?? '');

  // Redirect to webpack dev server if available
  if (isDev && devServerBase && !isAbsolutePath && !isFontRequest) {
    return proxyRequest(request, urlObject, devServerBase, {
      bypassCustomProtocolHandlers: false,
    });
  }
  const clonedRequest = Object.assign(request.clone(), {
    bypassCustomProtocolHandlers: true,
  });
  // this will be file types (in the web-static folder)
  let filepath = '';

  // for relative path, load the file in resources
  if (!isAbsolutePath) {
    if (urlObject.pathname.split('/').at(-1)?.includes('.')) {
      const decodedPath = decodeURIComponent(urlObject.pathname).replace(
        /^\/+/,
        ''
      );
      filepath = resolvePathInBase(webStaticDir, decodedPath, {
        caseInsensitive: isWindows(),
        label: 'filepath',
      });
    } else {
      // else, fallback to load the index.html instead
      filepath = join(webStaticDir, 'index.html');
    }
  } else {
    filepath = decodeURIComponent(urlObject.pathname);
    // on windows, the path could be start with '/'
    if (isWindows()) {
      filepath = path.resolve(filepath.replace(/^\//, ''));
    }
    if (urlObject.host !== 'local-file' || !isPathInWhiteList(filepath)) {
      throw new Error('Invalid filepath');
    }
    filepath = await resolveWhitelistedLocalPath(filepath);
  }
  return net.fetch(pathToFileURL(filepath).toString(), clonedRequest);
}

const needRefererDomains = [
  /^(?:[a-zA-Z0-9-]+\.)*youtube\.com$/,
  /^(?:[a-zA-Z0-9-]+\.)*youtube-nocookie\.com$/,
  /^(?:[a-zA-Z0-9-]+\.)*googlevideo\.com$/,
];
const defaultReferer = 'https://client.affine.local/';
const affineDomains = [
  /^(?:[a-z0-9-]+\.)*usercontent\.affine\.pro$/i,
  /^(?:[a-z0-9-]+\.)*affine\.pro$/i,
  /^(?:[a-z0-9-]+\.)*affine\.fail$/i,
  /^(?:[a-z0-9-]+\.)*affine\.run$/i,
];

function setHeader(
  headers: Record<string, string[]>,
  name: string,
  value: string
) {
  Object.keys(headers).forEach(key => {
    if (key.toLowerCase() === name.toLowerCase()) {
      delete headers[key];
    }
  });
  headers[name] = [value];
}

function ensureFrameAncestors(
  headers: Record<string, string[]>,
  directive: string
) {
  const cspHeaderKey = Object.keys(headers).find(
    key => key.toLowerCase() === 'content-security-policy'
  );
  if (!cspHeaderKey) {
    headers['Content-Security-Policy'] = [`frame-ancestors ${directive}`];
    return;
  }

  const values = headers[cspHeaderKey];
  headers[cspHeaderKey] = values.map(val => {
    if (typeof val !== 'string') return val as any;
    const directives = val
      .split(';')
      .map(v => v.trim())
      .filter(Boolean)
      .filter(d => !d.toLowerCase().startsWith('frame-ancestors'));
    directives.push(`frame-ancestors ${directive}`);
    return directives.join('; ');
  });
}

function allowCors(
  headers: Record<string, string[]>,
  origin: string = 'assets://.'
) {
  // Object-storage upload and Copilot URLs do not include application CORS headers.
  setHeader(headers, 'Access-Control-Allow-Origin', origin);
  setHeader(headers, 'Access-Control-Allow-Credentials', 'true');
  setHeader(headers, 'Access-Control-Allow-Methods', 'GET, HEAD, PUT, OPTIONS');
  setHeader(
    headers,
    'Access-Control-Allow-Headers',
    '*, Authorization, Content-Type, Range'
  );
}

export async function registerProtocol() {
  await initializeAuthSessions();

  protocol.handle('assets', request => {
    return handleFileRequest(request);
  });

  session.defaultSession.webRequest.onHeadersReceived(
    (responseDetails, callback) => {
      const { responseHeaders, url } = responseDetails;
      (async () => {
        if (responseHeaders) {
          const { protocol, hostname } = new URL(url);

          // Adjust CORS for local assets and application-owned object storage.
          if (protocol === 'assets:') {
            delete responseHeaders['access-control-allow-origin'];
            delete responseHeaders['access-control-allow-headers'];
            delete responseHeaders['Access-Control-Allow-Origin'];
            delete responseHeaders['Access-Control-Allow-Headers'];
            setHeader(responseHeaders, 'X-Frame-Options', 'SAMEORIGIN');
            ensureFrameAncestors(responseHeaders, "'self'");
          } else if (
            (protocol === 'http:' || protocol === 'https:') &&
            affineDomains.some(regex => regex.test(hostname))
          ) {
            allowCors(responseHeaders);
          }
        }
      })()
        .catch(err => {
          logger.error('error handling headers received', err);
        })
        .finally(() => {
          callback({ responseHeaders });
        });
    }
  );

  session.defaultSession.webRequest.onBeforeSendHeaders((details, callback) => {
    const url = new URL(details.url);
    const managedAuthRequest =
      (url.protocol === 'http:' ||
        url.protocol === 'https:' ||
        url.protocol === 'ws:' ||
        url.protocol === 'wss:') &&
      isManagedAuthEndpoint(details.url);
    let cancel = false;

    (async () => {
      if (managedAuthRequest) {
        delete details.requestHeaders.authorization;
        delete details.requestHeaders.Authorization;
        const token = await getAccessTokenForUrl(details.url, 120_000);
        if (token) {
          details.requestHeaders.Authorization = `Bearer ${token}`;
        }
      }

      const hostname = url.hostname;
      const needReferer = needRefererDomains.some(regex =>
        regex.test(hostname)
      );
      if (needReferer && !details.requestHeaders['Referer']) {
        details.requestHeaders['Referer'] = defaultReferer;
      }
    })()
      .catch(err => {
        cancel = managedAuthRequest;
        logger.error('error handling before send headers', err);
      })
      .finally(() => {
        callback({
          cancel,
          requestHeaders: details.requestHeaders,
        });
      });
  });
}