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This commit is contained in:
Andras Schmelczer 2026-05-13 12:11:54 +01:00
parent a08b5d2ae0
commit b98f0e3904
38 changed files with 3732 additions and 483 deletions
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50
screenshot/src/screenshot.ts
View file

@ -7,6 +7,10 @@ const NAVIGATION_TIMEOUT = 15_000;
const READY_TIMEOUT = 15_000;
const RENDER_BUFFER_MS = 500;
const POOL_SIZE = 3;
// Abort screenshots whose main frame navigates more than this many times after
// the initial load. Protects against redirect loops triggered by malicious
// invite codes (e.g. client-side `location.href` chains).
const MAX_POST_LOAD_NAVIGATIONS = 5;
let browser: Browser | null = null;
let sharedContext: BrowserContext | null = null;
@ -124,7 +128,7 @@ async function ensureContext(): Promise<BrowserContext> {
body: entry.body,
});
} catch {
await route.continue().catch(() => {});
await route.continue().catch(() => { });
}
});
@ -152,11 +156,11 @@ async function warmPool(): Promise<void> {
async function acquirePage(): Promise<Page> {
const page = pagePool.shift();
if (page && !page.isClosed()) {
warmPool().catch(() => {});
warmPool().catch(() => { });
return page;
}
const newPage = await createPage();
warmPool().catch(() => {});
warmPool().catch(() => { });
return newPage;
}
@ -165,14 +169,14 @@ async function releasePage(page: Page): Promise<void> {
if (page.isClosed()) return;
// Navigate to blank to free rendered page resources (DOM, WebGL context)
// while keeping the page object alive for V8 code cache reuse
await page.goto('about:blank', { timeout: 5000 }).catch(() => {});
await page.goto('about:blank', { timeout: 5000 }).catch(() => { });
if (!page.isClosed() && pagePool.length < POOL_SIZE) {
pagePool.push(page);
} else {
await page.close().catch(() => {});
await page.close().catch(() => { });
}
} catch {
await page.close().catch(() => {});
await page.close().catch(() => { });
}
}
@ -206,11 +210,11 @@ export async function initialize(appUrl: string): Promise<void> {
// Non-fatal — cache will still have JS/CSS/tiles from the partial load
}
console.log(`Pre-warm complete. Cache: ${networkCache.stats()}`);
await page.close().catch(() => {});
await page.close().catch(() => { });
await warmPool();
return;
} catch (err) {
await page.close().catch(() => {});
await page.close().catch(() => { });
if (attempt === MAX_RETRIES) {
console.warn(`Pre-warm failed after ${MAX_RETRIES} attempts (non-fatal):`, err);
} else {
@ -230,6 +234,17 @@ export async function takeScreenshot(url: string, authHeader?: string): Promise<
const page = await acquirePage();
const t0 = performance.now();
let postLoadNavigations = 0;
let navigationLoopDetected = false;
const mainFrame = page.mainFrame();
const onNavigated = (frame: ReturnType<typeof page.mainFrame>) => {
if (frame !== mainFrame) return;
postLoadNavigations += 1;
if (postLoadNavigations > MAX_POST_LOAD_NAVIGATIONS) {
navigationLoopDetected = true;
}
};
try {
// Inject Authorization header on API requests so the headless browser
// is authenticated (required for licensed users outside the free zone).
@ -250,6 +265,10 @@ export async function takeScreenshot(url: string, authHeader?: string): Promise<
if (response) {
console.log(` Navigate: ${(t1 - t0).toFixed(0)}ms (status ${response.status()})`);
}
// Start counting only AFTER the initial navigation completes — the
// initial `goto` itself fires framenavigated, so we'd double-count.
postLoadNavigations = 0;
page.on('framenavigated', onNavigated);
// Wait for the frontend to signal that data is loaded and layers created
try {
@ -259,6 +278,12 @@ export async function takeScreenshot(url: string, authHeader?: string): Promise<
} catch {
console.warn(' Timed out waiting for __screenshot_ready');
}
if (navigationLoopDetected) {
throw new Error(
`Navigation loop detected (${postLoadNavigations} post-load navigations)`,
);
}
const t2 = performance.now();
console.log(` Ready: ${(t2 - t1).toFixed(0)}ms`);
@ -277,10 +302,11 @@ export async function takeScreenshot(url: string, authHeader?: string): Promise<
return Buffer.from(screenshot);
} finally {
page.off('framenavigated', onNavigated);
// Remove page-level auth route before returning page to pool
// so the next screenshot doesn't inherit stale credentials
if (authHeader) {
await page.unrouteAll({ behavior: 'wait' }).catch(() => {});
await page.unrouteAll({ behavior: 'wait' }).catch(() => { });
}
await releasePage(page);
}
@ -311,17 +337,17 @@ export async function checkWebGL(): Promise<Record<string, unknown>> {
export async function closeBrowser(): Promise<void> {
for (const page of pagePool) {
await page.close().catch(() => {});
await page.close().catch(() => { });
}
pagePool.length = 0;
if (sharedContext) {
await sharedContext.close().catch(() => {});
await sharedContext.close().catch(() => { });
sharedContext = null;
}
if (browser) {
await browser.close().catch(() => {});
await browser.close().catch(() => { });
browser = null;
}
}

43
screenshot/src/validation.test.ts
View file

@ -16,8 +16,17 @@ test('buildScreenshotRequest accepts supported screenshot parameters', () => {
crime: ['Burglary (avg/yr):0:5', 'Vehicle crime (avg/yr):0:10'],
voteShare: ['% Labour:30:55', '% Conservative:10:35'],
ethnicity: ['% White:10:80', '% South Asian:5:35'],
amenityDistance: [
'Distance%20to%20nearest%20amenity%20(Park)%20(km):0:0.4',
'Distance%20to%20nearest%20amenity%20(Caf%C3%A9)%20(km):0:1.5',
],
transportDistance: 'Distance%20to%20nearest%20amenity%20(Bus%20stop)%20(km):0:0.3',
amenityCount2km: 'Number%20of%20amenities%20(Cafe)%20within%202km:2:8',
amenityCount5km: 'Number%20of%20amenities%20(Park)%20within%205km:1:20',
poi: 'supermarket',
tt: 'transit:kings-cross:Kings Cross:b:0:30',
share: 'abc123',
pc: 'SW1A 1AA',
});
assert.equal(result.pagePath, '/invite/abc123');
@ -36,6 +45,31 @@ test('buildScreenshotRequest accepts supported screenshot parameters', () => {
]);
assert.deepEqual(result.qs.getAll('voteShare'), ['% Labour:30:55', '% Conservative:10:35']);
assert.deepEqual(result.qs.getAll('ethnicity'), ['% White:10:80', '% South Asian:5:35']);
assert.deepEqual(result.qs.getAll('amenityDistance'), [
'Distance%20to%20nearest%20amenity%20(Park)%20(km):0:0.4',
'Distance%20to%20nearest%20amenity%20(Caf%C3%A9)%20(km):0:1.5',
]);
assert.deepEqual(result.qs.getAll('transportDistance'), [
'Distance%20to%20nearest%20amenity%20(Bus%20stop)%20(km):0:0.3',
]);
assert.deepEqual(result.qs.getAll('amenityCount2km'), [
'Number%20of%20amenities%20(Cafe)%20within%202km:2:8',
]);
assert.deepEqual(result.qs.getAll('amenityCount5km'), [
'Number%20of%20amenities%20(Park)%20within%205km:1:20',
]);
assert.equal(result.qs.get('share'), 'abc123');
assert.equal(result.qs.get('pc'), 'SW1A 1AA');
});
test('buildScreenshotRequest safely passes through future dashboard parameters', () => {
const result = buildScreenshotRequest({
futureFilter: ['alpha:1:2', 'beta:3:4'],
viewMode_2: 'postcode',
});
assert.deepEqual(result.qs.getAll('futureFilter'), ['alpha:1:2', 'beta:3:4']);
assert.equal(result.qs.get('viewMode_2'), 'postcode');
});
test('buildScreenshotRequest rejects invalid numeric values', () => {
@ -67,3 +101,12 @@ test('buildScreenshotRequest limits repeated parameters', () => {
test('buildScreenshotRequest rejects control characters', () => {
assert.throws(() => buildScreenshotRequest({ filter: 'Feature:\u0000:1' }), ValidationError);
});
test('buildScreenshotRequest rejects reserved screenshot service parameters', () => {
assert.throws(() => buildScreenshotRequest({ screenshot: '0' }), ValidationError);
assert.throws(() => buildScreenshotRequest({ _auth: '1' }), ValidationError);
});
test('buildScreenshotRequest rejects unsafe passthrough parameter names', () => {
assert.throws(() => buildScreenshotRequest({ 'filter[]': 'Feature:0:1' }), ValidationError);
});

65
screenshot/src/validation.ts
View file

@ -8,11 +8,27 @@ export interface ValidatedScreenshotRequest {
}
const MAX_REPEATED_PARAMS = 40;
const MAX_QUERY_KEYS = 80;
const MAX_VALUE_LENGTH = 500;
const NUMERIC_RE = /^-?(?:\d+|\d*\.\d+)$/;
const PATH_RE = /^\/(?:invite\/[A-Za-z0-9]{1,20})?$/;
const QUERY_KEY_RE = /^[A-Za-z][A-Za-z0-9_-]{0,63}$/;
const SAFE_VALUE_RE = /^[^\u0000-\u001f\u007f]+$/;
const REPEATED_KEYS = ['filter', 'school', 'crime', 'voteShare', 'ethnicity', 'poi', 'tt'] as const;
const REPEATED_KEYS = [
'filter',
'school',
'crime',
'voteShare',
'ethnicity',
'amenityDistance',
'transportDistance',
'amenityCount2km',
'amenityCount5km',
'poi',
'tt',
] as const;
const PASSTHROUGH_SINGLE_KEYS = ['share', 'pc'] as const;
const RESERVED_QUERY_KEYS = new Set(['path', 'screenshot', '_auth']);
type Query = Record<string, unknown>;
@ -56,6 +72,20 @@ function assertSafeValue(key: string, value: string): void {
}
}
function assertSafeKey(key: string): void {
if (!QUERY_KEY_RE.test(key)) {
validationError(`${key} is invalid`);
}
}
function appendSafeValues(qs: URLSearchParams, query: Query, key: string): void {
assertSafeKey(key);
for (const value of repeatedStrings(query, key)) {
assertSafeValue(key, value);
qs.append(key, value);
}
}
function appendBoundedNumber(
qs: URLSearchParams,
query: Query,
@ -76,7 +106,22 @@ function appendBoundedNumber(
}
export function buildScreenshotRequest(query: Query): ValidatedScreenshotRequest {
const queryKeys = Object.keys(query);
if (queryKeys.length > MAX_QUERY_KEYS) {
validationError('query has too many parameters');
}
const qs = new URLSearchParams();
const handledKeys = new Set<string>([
'lat',
'lon',
'zoom',
'tab',
'og',
'path',
...PASSTHROUGH_SINGLE_KEYS,
...REPEATED_KEYS,
]);
appendBoundedNumber(qs, query, 'lat', -90, 90);
appendBoundedNumber(qs, query, 'lon', -180, 180);
@ -98,11 +143,23 @@ export function buildScreenshotRequest(query: Query): ValidatedScreenshotRequest
qs.set('og', og);
}
for (const key of PASSTHROUGH_SINGLE_KEYS) {
const value = firstString(query, key);
if (value == null) continue;
assertSafeValue(key, value);
qs.set(key, value);
}
for (const key of REPEATED_KEYS) {
for (const value of repeatedStrings(query, key)) {
assertSafeValue(key, value);
qs.append(key, value);
appendSafeValues(qs, query, key);
}
for (const key of queryKeys) {
if (handledKeys.has(key)) continue;
if (RESERVED_QUERY_KEYS.has(key)) {
validationError(`${key} is reserved`);
}
appendSafeValues(qs, query, key);
}
const pagePath = firstString(query, 'path') ?? '/';