Handle invalid IPs and localhost lookup failures in location detection

src/lib/detect.test.ts

@@ -1,8 +1,23 @@
-import { expect, test } from 'vitest';
+import { beforeEach, expect, test, vi } from 'vitest';
+import { getLocation, hasBlockedIp } from './detect';
 import { getIpAddress } from './ip';
 
 const IP = '127.0.0.1';
 
+const isLocalhost = vi.mocked(await import('is-localhost-ip'));
+
+vi.mock('is-localhost-ip', () => ({
+  default: vi.fn(),
+}));
+
+beforeEach(() => {
+  vi.resetAllMocks();
+
+  delete process.env.CLIENT_IP_HEADER;
+  delete process.env.IGNORE_IP;
+  delete process.env.SKIP_LOCATION_HEADERS;
+});
+
 test('getIpAddress: Custom header', () => {
   process.env.CLIENT_IP_HEADER = 'x-custom-ip-header';
 
@@ -20,3 +35,43 @@ test('getIpAddress: Standard header', () => {
 test('getIpAddress: No header', () => {
   expect(getIpAddress(new Headers())).toEqual(undefined);
 });
+
+test('getLocation: returns null for malformed ip', async () => {
+  await expect(
+    getLocation(
+      'not-an-ip',
+      new Headers({
+        'cf-ipcountry': 'US',
+        'cf-region-code': 'CA',
+        'cf-ipcity': 'Los Angeles',
+      }),
+      false,
+    ),
+  ).resolves.toEqual(null);
+});
+
+test('getLocation: treats localhost check errors as non-local', async () => {
+  isLocalhost.default.mockRejectedValue(new Error('DNS Lookup failed.'));
+
+  await expect(
+    getLocation(
+      '8.8.8.8',
+      new Headers({
+        'cf-ipcountry': 'US',
+        'cf-region-code': 'CA',
+        'cf-ipcity': 'Los Angeles',
+      }),
+      false,
+    ),
+  ).resolves.toEqual({
+    country: 'US',
+    region: 'US-CA',
+    city: 'Los Angeles',
+  });
+});
+
+test('hasBlockedIp: returns false for malformed client ip with cidr block', () => {
+  process.env.IGNORE_IP = '10.0.0.0/8';
+
+  expect(hasBlockedIp('not-an-ip')).toBe(false);
+});

src/lib/detect.ts

@@ -76,11 +76,19 @@ function decodeHeader(s: string | undefined | null): string | undefined | null {
   return Buffer.from(s, 'latin1').toString('utf-8');
 }
 
+async function isLocalIp(ip: string) {
+  try {
+    return await isLocalhost(ip);
+  } catch {
+    return false;
+  }
+}
+
 export async function getLocation(ip: string = '', headers: Headers, skipHeaders: boolean) {
   const cleanIp = stripPort(ip);
 
   // Ignore local or invalid ips
-  if (!cleanIp || !ipaddr.isValid(cleanIp) || (await isLocalhost(cleanIp))) {
+  if (!cleanIp || !ipaddr.isValid(cleanIp) || (await isLocalIp(cleanIp))) {
     return null;
   }