feat(node): fromNodeHeaders helper

docs/content/docs/integrations/node.mdx

@@ -26,4 +26,22 @@ app.listen(port, () => {
 });
 ```
 
-After completing the setup, start your server. Better Auth will be ready to use. You can send a `GET` request to the `/ok` endpoint (`/api/auth/ok`) to verify that the server is running.
+After completing the setup, start your server. Better Auth will be ready to use. You can send a `GET` request to the `/ok` endpoint (`/api/auth/ok`) to verify that the server is running.
+
+### Getting the User Session
+
+To retrieve the user's session, you can use the `getSession` method provided by the `auth` object. This method requires the request headers to be passed in a specific format. To simplify this process, Better Auth provides a `fromNodeHeaders` helper function that converts Node.js request headers to the format expected by Better Auth (a `Headers` object).
+
+Here's an example of how to use `getSession` in an Express route:
+
+```ts title="server.ts"
+import { fromNodeHeaders } from "better-auth/node";
+import { auth } from "./auth"; //your better auth instance
+
+app.get("/api/me", async (req, res) => {
+ 	const session = await auth.getSession({
+      headers: fromNodeHeaders(req.headers),
+    });
+	return res.json(session);
+});
+```

packages/better-auth/src/integrations/node.ts

@@ -1,6 +1,21 @@
 import { toNodeHandler as toNode } from "better-call";
 import type { Auth } from "../auth";
+import type { IncomingHttpHeaders } from "http";
 
 export const toNodeHandler = (auth: Auth | Auth["handler"]) => {
 	return "handler" in auth ? toNode(auth.handler) : toNode(auth);
 };
+
+export function fromNodeHeaders(nodeHeaders: IncomingHttpHeaders): Headers {
+	const webHeaders = new Headers();
+	for (const [key, value] of Object.entries(nodeHeaders)) {
+		if (value !== undefined) {
+			if (Array.isArray(value)) {
+				value.forEach((v) => webHeaders.append(key, v));
+			} else {
+				webHeaders.set(key, value);
+			}
+		}
+	}
+	return webHeaders;
+}