Pin camera sources by parsed URL

Camera catalog image URLs were pinned by string prefix, so a URL that only
began with the agency's directory before dot segments or an encoded separator
were resolved still counted as inside it. The pin now parses the URL and
requires the same scheme, the exact host, no credentials, the default port and
a normalized path inside the pinned directory. Redirects on a pinned host must
stay inside the same directory.

Document the response format checks and API response headers alongside the
existing server hardening notes.

src/data/cctvSourcePins.test.mjs

@@ -0,0 +1,106 @@
+// Camera catalogs are pinned to their agency's image directory. The pin is a
+// parsed-URL check, not a string prefix, so a path that only starts with the
+// directory before dot segments, an encoded separator, credentials or another
+// port are resolved never counts as inside it, and a redirect on a pinned host
+// cannot leave the directory either.
+//
+// Run with: npm test   (node --test)
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { loadTflSourcesFromOpenData } from '../../server/providers/cctv/sources.js';
+import { fetchWithinHost } from '../../server/providers/cctv/media.js';
+
+const BUCKET = 'https://s3-eu-west-1.amazonaws.com/jamcams.tfl.gov.uk/';
+
+/** One available JamCam whose frame is at `imageUrl`. */
+const jamCam = (n, imageUrl) => ({
+  id: `JamCams_00001.0000${n}`,
+  commonName: `JamCam ${n}`,
+  lat: 51.5072,
+  lon: -0.1276,
+  additionalProperties: [
+    { key: 'available', value: 'true' },
+    { key: 'imageUrl', value: imageUrl },
+  ],
+});
+
+test('TfL JamCams keep only frames inside the official bucket, by parsed URL', async (t) => {
+  t.mock.method(console, 'log', () => {});
+  t.mock.method(console, 'warn', () => {});
+  const accepted = [
+    [`${BUCKET}00001.00001.jpg`, `${BUCKET}00001.00001.jpg`],
+    [`${BUCKET}00001.00002.jpg?t=1`, `${BUCKET}00001.00002.jpg?t=1`],
+    [
+      'https://s3-eu-west-1.amazonaws.com:443/jamcams.tfl.gov.uk/00001.00003.jpg',
+      `${BUCKET}00001.00003.jpg`,
+    ],
+  ];
+  const rejected = [
+    `${BUCKET}../other/x.jpg`,
+    `${BUCKET}%2e%2e/other/x.jpg`,
+    `${BUCKET}%2E%2E/other/x.jpg`,
+    `${BUCKET}.%2e/other/x.jpg`,
+    `${BUCKET}..%2fother/x.jpg`,
+    `${BUCKET}..%5Cother/x.jpg`,
+    `${BUCKET}..\\other\\x.jpg`,
+    'https://s3-eu-west-1.amazonaws.com/jamcams.tfl.gov.uk.other/x.jpg',
+    'https://s3-eu-west-1.amazonaws.com/jamcams.tfl.gov.uk-other/x.jpg',
+    'https://s3-eu-west-1.amazonaws.com/other/jamcams.tfl.gov.uk/x.jpg',
+    'https://user:[email protected]/jamcams.tfl.gov.uk/x.jpg',
+    'https://s3-eu-west-1.amazonaws.com:8443/jamcams.tfl.gov.uk/x.jpg',
+    'http://s3-eu-west-1.amazonaws.com/jamcams.tfl.gov.uk/x.jpg',
+    'https://s3-eu-west-1.amazonaws.com.other.example/jamcams.tfl.gov.uk/x.jpg',
+    'not a url',
+  ];
+  t.mock.method(globalThis, 'fetch', async () =>
+    Response.json(
+      [...accepted.map(([url]) => url), ...rejected].map((url, i) =>
+        jamCam(i + 1, url),
+      ),
+    ),
+  );
+  const cameras = await loadTflSourcesFromOpenData();
+  assert.deepEqual(
+    cameras.map((camera) => camera.url),
+    accepted.map(([, normalized]) => normalized),
+  );
+});
+
+test('a redirect on a pinned camera host stays inside the pinned directory', async () => {
+  const redirectTo = (location) => async (url) =>
+    url === `${BUCKET}00001.00001.jpg`
+      ? new Response(null, { status: 302, headers: { location } })
+      : new Response('frame', { headers: { 'content-type': 'image/jpeg' } });
+  for (const location of [
+    '/jamcams.tfl.gov.uk.other/x.jpg',
+    '/other/x.jpg',
+    '/jamcams.tfl.gov.uk/../other/x.jpg',
+    '/jamcams.tfl.gov.uk/%2e%2e/other/x.jpg',
+    '/jamcams.tfl.gov.uk/..%2fother/x.jpg',
+  ])
+    assert.equal(
+      await fetchWithinHost(
+        `${BUCKET}00001.00001.jpg`,
+        {},
+        redirectTo(location),
+      ),
+      null,
+      location,
+    );
+  const followed = await fetchWithinHost(
+    `${BUCKET}00001.00001.jpg`,
+    {},
+    redirectTo('/jamcams.tfl.gov.uk/00001.00002.jpg'),
+  );
+  assert.equal(await followed.text(), 'frame');
+  // A host with no pinned directory keeps the same-origin rule alone.
+  const unpinned = await fetchWithinHost(
+    'https://cams.example/a/frame.jpg',
+    {},
+    async (url) =>
+      url === 'https://cams.example/a/frame.jpg'
+        ? new Response(null, { status: 302, headers: { location: '/b/x.jpg' } })
+        : new Response('frame'),
+  );
+  assert.equal(await unpinned.text(), 'frame');
+});