add script/worker.js

script/worker.js

@@ -0,0 +1,88 @@
+const WORKER_URL = "myworker.workers.dev";
+
+export default {
+  async fetch(request) {
+    try {
+      if (request.headers.get("x-relay-hop") === "1") {
+        return json({ e: "loop detected" }, 508);
+      }
+
+      const req = await request.json();
+
+      if (!req.u) {
+        return json({ e: "missing url" }, 400);
+      }
+
+      const targetUrl = new URL(req.u);
+
+      const BLOCKED_HOSTS = [
+        WORKER_URL,
+      ];
+
+      if (BLOCKED_HOSTS.some(h => targetUrl.hostname.endsWith(h))) {
+        return json({ e: "self-fetch blocked" }, 400);
+      }
+
+      const headers = new Headers();
+      if (req.h && typeof req.h === "object") {
+        for (const [k, v] of Object.entries(req.h)) {
+          headers.set(k, v);
+        }
+      }
+
+      headers.set("x-relay-hop", "1");
+
+      const fetchOptions = {
+        method: (req.m || "GET").toUpperCase(),
+        headers,
+        redirect: req.r === false ? "manual" : "follow"
+      };
+
+      if (req.b) {
+        const binary = Uint8Array.from(atob(req.b), c => c.charCodeAt(0));
+        fetchOptions.body = binary;
+      }
+
+      const resp = await fetch(targetUrl.toString(), fetchOptions);
+
+      // Read response safely (no stack overflow)
+      const buffer = await resp.arrayBuffer();
+      const uint8 = new Uint8Array(buffer);
+
+      let binary = "";
+      const chunkSize = 0x8000; // prevent call stack overflow
+
+      for (let i = 0; i < uint8.length; i += chunkSize) {
+        binary += String.fromCharCode.apply(
+          null,
+          uint8.subarray(i, i + chunkSize)
+        );
+      }
+
+      const base64 = btoa(binary);
+
+      const responseHeaders = {};
+      resp.headers.forEach((v, k) => {
+        responseHeaders[k] = v;
+      });
+
+      return json({
+        s: resp.status,
+        h: responseHeaders,
+        b: base64
+      });
+
+    } catch (err) {
+      return json({ e: String(err) }, 500);
+    }
+  }
+};
+
+function json(obj, status = 200) {
+  return new Response(JSON.stringify(obj), {
+    status,
+    headers: {
+      "content-type": "application/json"
+    }
+  });
+}