Skip to main content

clientInfo

Type: RequestHandler Access: nauth.middleware.clientInfo

Express middleware that extracts client information (IP address, user agent, device info) and initializes async local storage context.

Signature​

nauth.middleware.clientInfo: RequestHandler

Overview​

The clientInfo middleware automatically extracts client metadata from incoming requests and stores it in async local storage. This provides transparent access to client information throughout the request lifecycle.

Key Features:

  • Automatic IP address extraction (handles proxies/load balancers)
  • User agent parsing
  • Device token extraction
  • Optional geolocation data
  • Initializes async local storage context
warning

MUST BE FIRST - This middleware must be mounted before all other NAuth middleware as it initializes the context.

Usage​

Mount Order​

Client info middleware must be mounted first:

import express from 'express';
import { NAuth, ExpressAdapter } from '@nauth-toolkit/core';

const app = express();
const nauth = await NAuth.create({
  config: authConfig,
  dataSource,
  adapter: new ExpressAdapter(),
});

// MUST BE FIRST - Initializes context
app.use(nauth.middleware.clientInfo);
app.use(nauth.middleware.csrf);
app.use(nauth.middleware.auth);
app.use(nauth.middleware.tokenDelivery);

Access Client Info​

Client information is automatically available via nauth.helpers.getCurrentUser() or context:

app.get('/api/info', async (req, res) => {
  // Client info is automatically extracted
  const clientInfo = nauth.helpers.getCurrentUser(); // Or from context
  res.json({
    ipAddress: clientInfo?.ipAddress,
    userAgent: clientInfo?.userAgent,
  });
});

Behavior​

  • Extracts IP address from req.ip (set by Express after applying trust proxy rules)
  • Parses user agent string
  • Extracts device token from request body or headers
  • Optionally performs geolocation lookup
  • Stores data in async local storage for transparent access

Proxy Trust​

The middleware reads the client IP from Express's req.ip. Express only populates req.ip from forwarding headers (X-Forwarded-For, etc.) when trust proxy is configured on the Express app. Without it, req.ip will be the IP of the last network hop (e.g. your load balancer), not the real client.

Configure trust proxy on your Express application before mounting NAuth middleware:

import express from 'express';

const app = express();

// Trust the first proxy in front of the app (e.g. a single Nginx or AWS ALB)
app.set('trust proxy', 1);

// For multiple known proxy IPs or CIDR ranges:
// app.set('trust proxy', ['loopback', '10.0.0.0/8']);

app.use(nauth.middleware.clientInfo);
// ...

See the Express behind proxies guide for all valid values.

Configuration​

Geolocation is optional and requires GeoLocationService:

const nauth = await NAuth.create({
  config: {
    // Geolocation config (optional)
  },
  dataSource,
  adapter: new ExpressAdapter(),
});
Last updated on