feat(ip): support cidr strings in proxies (#5394)

Closes GH-5382.

Author: wooorm-arcjet

ip/index.ts

@@ -857,7 +857,21 @@ export function findIp(
   request: RequestLike,
   options?: Options | null | undefined,
 ): string {
-  const { platform, proxies } = options || {};
+  const { platform, proxies: rawProxies } = options || {};
+  const proxies: Array<Cidr | string> = [];
+
+  if (Array.isArray(rawProxies)) {
+    for (const cidrOrIp of rawProxies) {
+      if (typeof cidrOrIp === "string") {
+        proxies.push(parseProxy(cidrOrIp));
+      }
+
+      if (isIpv4Cidr(cidrOrIp) || isIpv6Cidr(cidrOrIp)) {
+        proxies.push(cidrOrIp);
+      }
+    }
+  }
+
   // Prefer anything available via the platform over headers since headers can
   // be set by users. Only if we don't have an IP available in `request` do we
   // search the `headers`.

ip/test/ip.test.ts

@@ -249,6 +249,51 @@ test("`findIp`", async (t) => {
     },
   );
 
+  await t.test("should support an IP string in a proxy", function () {
+    assert.equal(
+      findIp(
+        { headers: { "x-forwarded-for": "1.1.1.1, 2.2.2.2, 3.3.3.3" } },
+        { proxies: ["3.3.3.3"] },
+      ),
+      "2.2.2.2",
+    );
+  });
+
+  await t.test("should support an CIDR string in a proxy", function () {
+    assert.equal(
+      findIp(
+        { headers: { "x-forwarded-for": "1.1.1.1, 2.2.2.2, 3.3.3.3" } },
+        { proxies: ["3.3.3.3/32"] },
+      ),
+      "2.2.2.2",
+    );
+  });
+
+  await t.test("should support an CIDR object in a proxy", function () {
+    assert.equal(
+      findIp(
+        { headers: { "x-forwarded-for": "1.1.1.1, 2.2.2.2, 3.3.3.3" } },
+        { proxies: [parseProxy("3.3.3.3/32")] },
+      ),
+      "2.2.2.2",
+    );
+  });
+
+  await t.test("should filter an invalid value in a proxy", function () {
+    assert.equal(
+      findIp(
+        { headers: { "x-forwarded-for": "1.1.1.1, 2.2.2.2, 3.3.3.3" } },
+        {
+          proxies: [
+            // @ts-expect-error: Testing type annotation violations
+            123456789,
+          ],
+        },
+      ),
+      "3.3.3.3",
+    );
+  });
+
   await t.test("request: `ip`", async (t) => {
     for (const [message, input, expected, proxies] of cases) {
       await t.test(message, () => {