openchamber/packages/web/server/lib/preview/proxy-runtime.test.js

import { describe, expect, it } from 'vitest';

import {
  classifyPreviewNavigation,
  classifyPreviewResourceError,
  normalizeProxyTargetUrl,
  rewritePreviewBody,
  rewritePreviewCspHeader,
  rewritePreviewRedirectLocation,
} from './proxy-runtime.js';

const rewrite = (bodyText, kind) => rewritePreviewBody({
  bodyText,
  kind,
  proxyBasePath: '/api/preview/proxy/abc123',
  targetOrigin: 'http://127.0.0.1:3000',
});

describe('preview resource error classification', () => {
  it('suppresses Astro/Vite stylesheet modules reported as failed scripts', () => {
    expect(classifyPreviewResourceError({
      tagName: 'script',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/src/styles/global.css',
    })).toBe('suppress');

    expect(classifyPreviewResourceError({
      tagName: 'script',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/src/pages/support.astro?astro&type=style&index=0&lang.css',
    })).toBe('suppress');
  });

  it('suppresses framework virtual modules reported by dev servers', () => {
    expect(classifyPreviewResourceError({
      tagName: 'script',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/src/layouts/BaseLayout.astro?astro&type=script&index=0&lang.ts',
    })).toBe('suppress');

    expect(classifyPreviewResourceError({
      tagName: 'script',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/@vite/client',
    })).toBe('suppress');

    expect(classifyPreviewResourceError({
      tagName: 'link',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/@id/astro:scripts/page.js',
    })).toBe('suppress');
  });

  it('suppresses conservative ecosystem dev-runtime resources', () => {
    const noisyResources = [
      '/_next/static/chunks/webpack.js',
      '/_next/static/chunks/react-refresh.js',
      '/.svelte-kit/generated/client/app.js',
      '/@id/__x00__virtual:sveltekit:browser',
      '/@remix-run/dev/dist/browser.js',
      '/__hmr?runtime=remix',
      '/_nuxt/@vite/client',
      '/_nuxt/@id/virtual:nuxt:%2FUsers%2Fapp',
      '/webpack-dev-server/client/index.js',
      '/webpack/hot/dev-server.js',
      '/__webpack_hmr',
    ];

    for (const resource of noisyResources) {
      expect(classifyPreviewResourceError({
        tagName: 'script',
        url: `http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc${resource}`,
      })).toBe('suppress');
    }
  });

  it('keeps ordinary application resource failures visible', () => {
    expect(classifyPreviewResourceError({
      tagName: 'script',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/assets/app.js',
    })).toBe('report');

    expect(classifyPreviewResourceError({
      tagName: 'img',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/missing.png',
    })).toBe('report');

    expect(classifyPreviewResourceError({
      tagName: 'link',
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/styles/missing.css',
    })).toBe('report');
  });
});

describe('preview body URL rewriting', () => {
  it('rewrites only HTML resource attributes in HTML responses', () => {
    const input = '<img src="/logo.png"><a href="/docs">Docs</a><script>const url = "/api/data";</script>';
    const output = rewrite(input, 'html');

    expect(output).toContain('src="/api/preview/proxy/abc123/logo.png"');
    expect(output).toContain('href="/api/preview/proxy/abc123/docs"');
    expect(output).toContain('const url = "/api/data";');
  });

  it('removes CSP meta tags that block the preview bridge', () => {
    const input = '<meta http-equiv="Content-Security-Policy" content="script-src \'self\'"><div>Preview</div>';
    const output = rewrite(input, 'html');

    expect(output).not.toContain('Content-Security-Policy');
    expect(output).toContain('<div>Preview</div>');
  });

  it('adds preview and URL auth tokens to rewritten proxy resources when provided', () => {
    const output = rewritePreviewBody({
      bodyText: '<script src="/entry.js"></script><a href="http://localhost:3000/docs?x=1&oc_client_token=legacy">Docs</a>',
      kind: 'html',
      proxyBasePath: '/api/preview/proxy/abc123',
      targetOrigin: 'http://127.0.0.1:3000',
      previewToken: 'preview-secret',
      urlAuthToken: 'url-secret',
    });

    expect(output).toContain('src="/api/preview/proxy/abc123/entry.js?oc_preview_token=preview-secret&oc_url_token=url-secret"');
    expect(output).toContain('href="/api/preview/proxy/abc123/docs?x=1&oc_preview_token=preview-secret&oc_url_token=url-secret"');
    expect(output).not.toContain('oc_client_token');
  });

  it('rewrites only CSS imports and url references in CSS responses', () => {
    const input = '@import "/theme.css"; .hero { background: url(/hero.png); } .copy::after { content: "/not-a-url"; }';
    const output = rewrite(input, 'css');

    expect(output).toContain('@import "/api/preview/proxy/abc123/theme.css"');
    expect(output).toContain('url(/api/preview/proxy/abc123/hero.png)');
    expect(output).toContain('content: "/not-a-url"');
  });

  it('rewrites only JavaScript static import specifiers in JavaScript responses', () => {
    const input = 'import "/entry.js"; import value from "/module.js"; const url = "/api/data"; fetch("/api/data");';
    const output = rewrite(input, 'javascript');

    expect(output).toContain('import "/api/preview/proxy/abc123/entry.js"');
    expect(output).toContain('from "/api/preview/proxy/abc123/module.js"');
    expect(output).toContain('const url = "/api/data"');
    expect(output).toContain('fetch("/api/data")');
  });

  it('adds URL auth tokens to CSS and JavaScript rewritten resources', () => {
    const cssOutput = rewritePreviewBody({
      bodyText: '@import "/theme.css"; .hero { background: url(/hero.png); }',
      kind: 'css',
      proxyBasePath: '/api/preview/proxy/abc123',
      targetOrigin: 'http://127.0.0.1:3000',
      previewToken: 'preview-secret',
      urlAuthToken: 'url-secret',
    });
    const jsOutput = rewritePreviewBody({
      bodyText: 'import("/entry.js"); import value from "/module.js";',
      kind: 'javascript',
      proxyBasePath: '/api/preview/proxy/abc123',
      targetOrigin: 'http://127.0.0.1:3000',
      previewToken: 'preview-secret',
      urlAuthToken: 'url-secret',
    });

    expect(cssOutput).toContain('@import "/api/preview/proxy/abc123/theme.css?oc_preview_token=preview-secret&oc_url_token=url-secret"');
    expect(cssOutput).toContain('url(/api/preview/proxy/abc123/hero.png?oc_preview_token=preview-secret&oc_url_token=url-secret)');
    expect(jsOutput).toContain('import("/api/preview/proxy/abc123/entry.js?oc_preview_token=preview-secret&oc_url_token=url-secret")');
    expect(jsOutput).toContain('from "/api/preview/proxy/abc123/module.js?oc_preview_token=preview-secret&oc_url_token=url-secret"');
  });
});

describe('preview redirect URL rewriting', () => {
  it('rewrites loopback redirects through the preview proxy', () => {
    expect(rewritePreviewRedirectLocation({
      location: 'http://localhost:3000/login?next=%2F#top',
      proxyBasePath: '/api/preview/proxy/abc123',
      targetOrigin: 'http://127.0.0.1:3000',
    })).toBe('/api/preview/proxy/abc123/login?next=%2F#top');
  });

  it('leaves external redirects unchanged', () => {
    expect(rewritePreviewRedirectLocation({
      location: 'https://example.com/login',
      proxyBasePath: '/api/preview/proxy/abc123',
      targetOrigin: 'http://127.0.0.1:3000',
    })).toBe('https://example.com/login');
  });

  it('adds proxy auth tokens to loopback redirects when provided', () => {
    expect(rewritePreviewRedirectLocation({
      location: 'http://localhost:3000/login?next=%2F#top',
      proxyBasePath: '/api/preview/proxy/abc123',
      targetOrigin: 'http://127.0.0.1:3000',
      previewToken: 'preview-secret',
      urlAuthToken: 'url-secret',
    })).toBe('/api/preview/proxy/abc123/login?next=%2F&oc_preview_token=preview-secret&oc_url_token=url-secret#top');
  });

  it('leaves redirects unchanged when no target origin is provided', () => {
    expect(rewritePreviewRedirectLocation({
      location: 'http://localhost:5174/callback',
      proxyBasePath: '/api/preview/proxy/abc123',
      previewToken: 'preview-secret',
    })).toBe('http://localhost:5174/callback');
  });
});

describe('preview navigation policy', () => {
  const currentUrl = 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/docs';

  it('keeps same-page hash and already-proxied links in the iframe', () => {
    expect(classifyPreviewNavigation({ url: '#section', currentUrl }).action).toBe('allow');
    expect(classifyPreviewNavigation({
      url: 'http://127.0.0.1:57123/api/preview/proxy/f4af70b4261d77706743959516f9cecc/roadmap',
      currentUrl,
    }).action).toBe('allow');
  });

  it('routes loopback absolute links through the preview proxy', () => {
    expect(classifyPreviewNavigation({ url: 'http://localhost:3000/roadmap', currentUrl })).toEqual({
      action: 'proxy',
      url: 'http://localhost:3000/roadmap',
    });
  });

  it('maps app-origin root links back to the upstream origin while proxied', () => {
    expect(classifyPreviewNavigation({
      url: 'http://127.0.0.1:57123/support',
      currentUrl,
      targetOrigin: 'https://openchamber.dev',
    })).toEqual({
      action: 'proxy',
      url: 'https://openchamber.dev/support',
    });
  });

  it('sends non-loopback http links outside the preview iframe', () => {
    expect(classifyPreviewNavigation({ url: 'https://example.com/docs', currentUrl })).toEqual({
      action: 'external',
      url: 'https://example.com/docs',
    });
  });

  it('leaves non-http links to browser defaults', () => {
    expect(classifyPreviewNavigation({ url: 'mailto:test@example.com', currentUrl })).toEqual({
      action: 'allow',
      url: 'mailto:test@example.com',
    });
  });
});

describe('proxy target normalization (SSRF guard)', () => {
  it('allows ordinary external hosts when allowExternal is set', () => {
    expect(normalizeProxyTargetUrl('https://docs.openchamber.dev/security/', { allowExternal: true }))
      .toEqual({ ok: true, origin: 'https://docs.openchamber.dev' });
  });

  it('rejects non-loopback hosts without allowExternal', () => {
    expect(normalizeProxyTargetUrl('https://example.com/', {}).ok).toBe(false);
  });

  it('refuses private, loopback and link-local literals on the external path', () => {
    for (const url of [
      'http://127.0.0.1/',
      'http://10.0.0.5/',
      'http://172.16.9.9/',
      'http://192.168.1.1/',
      'http://169.254.169.254/latest/meta-data/',
      'http://100.64.0.1/',
      'http://localhost/',
      'http://service.local/',
      'http://[::1]/',
      'http://[fd00::1]/',
      'http://[fe80::1]/',
      'http://2130706433/', // decimal form of 127.0.0.1, normalized by WHATWG URL
    ]) {
      expect(normalizeProxyTargetUrl(url, { allowExternal: true }).ok, url).toBe(false);
    }
  });

  it('still blocks private hosts even via IPv4-mapped IPv6', () => {
    expect(normalizeProxyTargetUrl('http://[::ffff:127.0.0.1]/', { allowExternal: true }).ok).toBe(false);
  });
});

describe('preview CSP rewrite', () => {
  it('drops frame-ancestors and require-trusted-types-for but keeps the rest', () => {
    const result = rewritePreviewCspHeader(
      "default-src 'self'; frame-ancestors 'none'; require-trusted-types-for 'script'",
      'abc123',
    );
    expect(result).not.toContain('frame-ancestors');
    expect(result).not.toContain('require-trusted-types-for');
    expect(result).toContain("default-src 'self'");
  });

  it('adds the nonce to an existing script-src instead of removing it', () => {
    const result = rewritePreviewCspHeader("script-src 'self'", 'abc123');
    expect(result).toContain("script-src 'self' 'nonce-abc123'");
  });

  it('adds the nonce to script-src-elem when present', () => {
    const result = rewritePreviewCspHeader("script-src-elem 'self'", 'abc123');
    expect(result).toContain("script-src-elem 'self' 'nonce-abc123'");
  });

  it('synthesizes script-src from default-src when no script directive exists', () => {
    const result = rewritePreviewCspHeader("default-src 'self' https://cdn.example.com", 'abc123');
    expect(result).toContain("default-src 'self' https://cdn.example.com");
    expect(result).toContain("script-src 'self' https://cdn.example.com 'nonce-abc123'");
  });

  it("drops a lone 'none' so the nonce takes effect", () => {
    const result = rewritePreviewCspHeader("script-src 'none'", 'abc123');
    expect(result).toBe("script-src 'nonce-abc123'");
  });

  it('returns empty/unset CSP values unchanged', () => {
    expect(rewritePreviewCspHeader('', 'abc123')).toBe('');
    expect(rewritePreviewCspHeader(undefined, 'abc123')).toBe(undefined);
  });
});