shim plugin related APIs, proxy web requests.

shims/request-url.js

@@ -0,0 +1,111 @@
+// Override window.requestUrl to proxy external requests through our server,
+// bypassing browser CORS restrictions. Obsidian sets window.requestUrl = UA
+// in app.js, so we override it after app.js loads.
+
+function base64ToArrayBuffer(base64) {
+  const binary = atob(base64);
+  const bytes = new Uint8Array(binary.length);
+  for (let i = 0; i < binary.length; i++) {
+    bytes[i] = binary.charCodeAt(i);
+  }
+  return bytes.buffer;
+}
+
+function arrayBufferToBase64(buf) {
+  const bytes = new Uint8Array(buf);
+  let binary = "";
+  const chunk = 8192;
+  for (let i = 0; i < bytes.length; i += chunk) {
+    binary += String.fromCharCode.apply(null, bytes.subarray(i, i + chunk));
+  }
+  return btoa(binary);
+}
+
+async function proxyRequestUrl(request) {
+  if (typeof request === "string") {
+    request = { url: request };
+  }
+
+  const isSameOrigin =
+    request.url.startsWith(window.location.origin) ||
+    request.url.startsWith("/");
+
+  // Same-origin requests don't need the proxy
+  if (isSameOrigin) {
+    const res = await fetch(request.url, {
+      method: request.method || "GET",
+      headers: request.headers || {},
+      body: request.body,
+    });
+    const arrayBuf = await res.arrayBuffer();
+    return makeResponse(
+      request,
+      res.status,
+      Object.fromEntries(res.headers),
+      arrayBuf,
+    );
+  }
+
+  // Cross-origin: route through server proxy
+  let body = request.body;
+  let binary = false;
+  if (body instanceof ArrayBuffer) {
+    body = arrayBufferToBase64(body);
+    binary = true;
+  }
+
+  const res = await fetch("/api/proxy", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({
+      url: request.url,
+      method: request.method || "GET",
+      headers: request.headers || {},
+      body,
+      binary,
+    }),
+  });
+
+  if (!res.ok) {
+    const err = await res
+      .json()
+      .catch(() => ({ error: "Proxy request failed" }));
+    throw new Error(err.error);
+  }
+
+  const proxyResult = await res.json();
+  const arrayBuf = base64ToArrayBuffer(proxyResult.body);
+  return makeResponse(
+    request,
+    proxyResult.status,
+    proxyResult.headers,
+    arrayBuf,
+  );
+}
+
+function makeResponse(request, status, headers, arrayBuf) {
+  const text = new TextDecoder().decode(arrayBuf);
+  let json;
+  try {
+    json = JSON.parse(text);
+  } catch {
+    json = null;
+  }
+  return { status, headers, arrayBuffer: arrayBuf, text, json };
+}
+
+export function installRequestUrlShim() {
+  // Obsidian sets window.requestUrl in app.js. We override it once the page loads.
+  // Use a getter so it intercepts even if app.js sets it later.
+  let _original = null;
+
+  Object.defineProperty(window, "requestUrl", {
+    get() {
+      return proxyRequestUrl;
+    },
+    set(val) {
+      _original = val;
+    },
+    configurable: true,
+  });
+}