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fix: prevent unhandled exception crashes for invalid header values #9638

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Apr 13, 2023
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5 changes: 5 additions & 0 deletions .changeset/swift-ads-itch.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@sveltejs/kit': patch
---

fix: prevent unhandled exceptions for invalid header values
29 changes: 18 additions & 11 deletions packages/kit/src/exports/node/index.js
Original file line number Diff line number Diff line change
Expand Up @@ -105,29 +105,36 @@ export async function getRequest({ request, base, bodySizeLimit }) {

/** @type {import('@sveltejs/kit/node').setResponse} */
export async function setResponse(res, response) {
const headers = Object.fromEntries(response.headers);

if (response.headers.has('set-cookie')) {
const header = /** @type {string} */ (response.headers.get('set-cookie'));
const split = set_cookie_parser.splitCookiesString(header);

// @ts-expect-error
headers['set-cookie'] = split;
for (const [key, value] of response.headers) {
try {
res.setHeader(
key,
key === 'set-cookie'
? set_cookie_parser.splitCookiesString(
// This is absurd but necessary, TODO: investigate why
/** @type {string}*/ (response.headers.get(key))
)
: value
);
} catch (error) {
res.getHeaderNames().forEach((name) => res.removeHeader(name));
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Not sure on this one - should we just remove all headers, or just the ones up until the error, or try to parse the other headers and add all but the invalid ones? Are there any security implications to this?

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My thinking was that it's an entirely different response because of the error and it shouldn't carry over any of the original headers.

should we just remove all headers, or just the ones up until the error

In its current state at least, those two would mean the same as all the headers haven't yet been copied over to the res object yet, in essence we're undoing earlier iterations of this loop.

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I would agree with @gtm-nayan's implementation and reasoning

res.writeHead(500).end(String(error));
return;
}
}

res.writeHead(response.status, headers);
res.writeHead(response.status);

if (!response.body) {
res.end();
return;
}

if (response.body.locked) {
res.write(
res.end(
'Fatal error: Response body is locked. ' +
`This can happen when the response was already read (for example through 'response.json()' or 'response.text()').`
);
res.end();
return;
}

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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
import { json } from '@sveltejs/kit';

/** @type {import('@sveltejs/kit').RequestHandler} */
export function GET({ setHeaders }) {
setHeaders({
'x-test': '\u001f'
});

return json({});
}
22 changes: 16 additions & 6 deletions packages/kit/test/apps/basics/test/server.test.js
Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,15 @@ test.describe('Endpoints', () => {
expect(await response.text()).toEqual(digest);
});

// TODO see above
test('invalid headers return a 500', async ({ request }) => {
const response = await request.get('/endpoint-output/head-write-error');
expect(response.status()).toBe(500);
expect(await response.text()).toMatch(
'TypeError [ERR_INVALID_CHAR]: Invalid character in header content ["x-test"]'
);
});

test('OPTIONS handler', async ({ request }) => {
const url = '/endpoint-output/options';

Expand Down Expand Up @@ -485,19 +494,20 @@ test.describe('setHeaders', () => {
test('allows multiple set-cookie headers with different values', async ({ page }) => {
const response = await page.goto('/headers/set-cookie/sub');
const cookies = (await response?.allHeaders())['set-cookie'];
expect(cookies.includes('cookie1=value1') && cookies.includes('cookie2=value2')).toBe(true);

expect(cookies).toMatch('cookie1=value1');
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should we also check that there are no unexpected values?

expect(cookies).toMatch('cookie2=value2');
});
});

test.describe('cookies', () => {
test('cookie.serialize created correct cookie header string', async ({ page }) => {
const response = await page.goto('/cookies/serialize');
const cookies = await response.headerValue('set-cookie');
expect(
cookies.includes('before=before') &&
cookies.includes('after=after') &&
cookies.includes('endpoint=endpoint')
).toBe(true);

expect(cookies).toMatch('before=before');
expect(cookies).toMatch('after=after');
expect(cookies).toMatch('endpoint=endpoint');
});
});

Expand Down