fix(validator): preserve repeated query parameters

packages/void/src/runtime/validator.ts

@@ -66,11 +66,12 @@ export async function runValidation<V extends ValidatorSlots>(
   }
 
   if (validators.query) {
-    const url = new URL(c.req.url);
-    const raw: Record<string, string> = {};
-    for (const [key, value] of url.searchParams) {
-      raw[key] = value;
-    }
+    const raw = Object.fromEntries(
+      Object.entries(c.req.queries()).map(([key, values]) => [
+        key,
+        values.length === 1 ? values[0] : values,
+      ]),
+    );
     const result = await validateSlot(validators.query, raw);
     if (result.ok) {
       input.query = result.value;

packages/void/test/unit/define-handler.test.ts

@@ -257,6 +257,40 @@ describe('defineHandler.withValidator', () => {
     expect(await res.json()).toEqual({ query: { page: '2', limit: '10' } });
   });
 
+  it('preserves repeated query params as arrays', async () => {
+    const handler = defineHandler.withValidator({
+      query: passSchema(),
+    })((_c, { query }) => {
+      return { query };
+    });
+
+    const app = createValidatedApp('get', '/test', handler);
+
+    const res = await app.request(new Request('http://localhost/test?page=2&tag=work&tag=urgent'));
+
+    expect(res.status).toBe(200);
+    expect(await res.json()).toEqual({
+      query: {
+        page: '2',
+        tag: ['work', 'urgent'],
+      },
+    });
+  });
+
+  it.each([
+    ['__proto__=work', 'work'],
+    ['__proto__=work&__proto__=urgent', ['work', 'urgent']],
+  ])('preserves %s as an own query property', async (search, expected) => {
+    const handler = defineHandler.withValidator({ query: passSchema() })((_c, { query }) => ({
+      query,
+    }));
+    const app = createValidatedApp('get', '/test', handler);
+    const res = await app.request(new Request(`http://localhost/test?${search}`));
+
+    expect(res.status).toBe(200);
+    expect(await res.json()).toEqual({ query: { ['__proto__']: expected } });
+  });
+
   it('validates route params', async () => {
     const handler = defineHandler.withValidator({
       params: passSchema(),

packages/void/test/unit/validator-real-schemas.test.ts

@@ -71,3 +71,20 @@ describe.each(libraries)('withValidator + $library', ({ CreateUser }) => {
     expect(json.issues[0].issues.length).toBeGreaterThanOrEqual(1);
   });
 });
+
+it('does not validate inherited array length as a query parameter', async () => {
+  const app = createPostApp(
+    defineHandler.withValidator({ query: z.object({ length: z.number() }) })(
+      (_c, { query }) => query,
+    ),
+  );
+  const res = await app.request(
+    new Request('http://localhost/test?__proto__=work&__proto__=urgent', { method: 'POST' }),
+  );
+
+  expect(res.status).toBe(400);
+  const json = (await res.json()) as ValidationIssueBody;
+  expect(json.error).toBe('Validation failed');
+  expect(json.issues[0].slot).toBe('query');
+  expect(json.issues[0].issues[0].path).toBe('length');
+});