feat: get req.ip from custom header

src/base-middleware.ts

@@ -13,6 +13,16 @@ export function setupBaseMiddleware(ctx: AppContext, expressApp: Express) {
             req.id = requestId;
             res.setHeader(requestIdHeaderName, requestId);
 
+            const expressClientIpHeaderName = ctx.config.expressClientIpHeaderName?.toLowerCase();
+            if (expressClientIpHeaderName) {
+                const clientIp = req.headers[expressClientIpHeaderName] as string | undefined;
+                Object.defineProperty(req, 'ip', {
+                    value: clientIp,
+                    writable: true,
+                    configurable: true,
+                });
+            }
+
             req.routeInfo = {};
 
             const startTime = Date.now();

src/tests/client-ip-header.test.ts

@@ -0,0 +1,122 @@
+import {ExpressKit, Request, Response} from '..';
+import {AppConfig, NodeKit} from '@gravity-ui/nodekit';
+import request from 'supertest';
+
+const APP_NAME = 'app';
+
+const setupApp = ({config}: {config?: AppConfig} = {}) => {
+    const logger = {
+        write: () => {},
+    };
+
+    const nodekit = new NodeKit({
+        config: {
+            appLoggingDestination: logger,
+            appName: APP_NAME,
+            ...config,
+        },
+    });
+
+    const routes = {
+        'GET /ip': {
+            handler: (req: Request, res: Response) => {
+                res.status(200);
+                res.send({ip: req.ip});
+            },
+        },
+    };
+
+    const app = new ExpressKit(nodekit, routes);
+
+    return {app, logger};
+};
+
+describe('expressClientIpHeaderName', () => {
+    it('should use default req.ip from X-Forwarded-For when expressClientIpHeaderName is not set', async () => {
+        const {app} = setupApp();
+
+        const forwardedIp = '198.51.100.25';
+
+        const agent = request.agent(app.express);
+
+        const response = await agent.get('/ip').set('X-Forwarded-For', forwardedIp);
+
+        expect(response.status).toBe(200);
+        expect(response.body.ip).toBe(forwardedIp);
+    });
+
+    it('should override req.ip with value from custom header when expressClientIpHeaderName is set', async () => {
+        const customIpHeader = 'X-Real-IP';
+        const customIp = '203.0.113.42';
+
+        const {app} = setupApp({
+            config: {
+                expressClientIpHeaderName: customIpHeader,
+            },
+        });
+
+        const agent = request.agent(app.express);
+
+        const response = await agent.get('/ip').set(customIpHeader, customIp);
+
+        expect(response.status).toBe(200);
+        expect(response.body.ip).toBe(customIp);
+    });
+
+    it('should be case-insensitive for header names', async () => {
+        const customIpHeader = 'X-Real-IP';
+        const customIp = '203.0.113.99';
+
+        const {app} = setupApp({
+            config: {
+                expressClientIpHeaderName: customIpHeader,
+            },
+        });
+
+        const agent = request.agent(app.express);
+
+        const response = await agent.get('/ip').set('x-real-ip', customIp);
+
+        expect(response.status).toBe(200);
+        expect(response.body.ip).toBe(customIp);
+    });
+
+    it('should set req.ip to undefined when custom header is not present in request', async () => {
+        const customIpHeader = 'X-Real-IP';
+
+        const {app} = setupApp({
+            config: {
+                expressClientIpHeaderName: customIpHeader,
+            },
+        });
+
+        const agent = request.agent(app.express);
+
+        const response = await agent.get('/ip');
+
+        expect(response.status).toBe(200);
+        expect(response.body.ip).toBeUndefined();
+    });
+
+    it('should use configured header when both x-forwarded-for and x-real-ip are present', async () => {
+        const customIpHeader = 'X-Real-IP';
+        const realIp = '203.0.113.50';
+        const forwardedIp = '198.51.100.25';
+
+        const {app} = setupApp({
+            config: {
+                expressClientIpHeaderName: customIpHeader,
+            },
+        });
+
+        const agent = request.agent(app.express);
+
+        const response = await agent
+            .get('/ip')
+            .set('X-Real-IP', realIp)
+            .set('X-Forwarded-For', forwardedIp);
+
+        expect(response.status).toBe(200);
+        expect(response.body.ip).toBe(realIp);
+    });
+});

src/types.ts

@@ -26,6 +26,7 @@ declare module '@gravity-ui/nodekit' {
         expressTrustProxyNumber?: number | boolean;
         expressCookieSecret?: string | string[];
         expressRequestIdHeaderName?: string;
+        expressClientIpHeaderName?: string;
 
         expressDisableBodyParserJSON?: boolean;
         expressBodyParserJSONConfig?: bodyParser.OptionsJson;