[security] Drop sensitive headers when following redirects (#2013)

Do not forward the `Authorization` and `Cookie` headers if the redirect
host is different from the original host.

Author: lpinca

Diff for: lib/websocket.js

@@ -766,6 +766,45 @@ function initAsClient(websocket, address, protocols, options) {
     opts.path = parts[1];
   }
 
+  if (opts.followRedirects) {
+    if (websocket._redirects === 0) {
+      websocket._originalHost = parsedUrl.host;
+
+      const headers = options && options.headers;
+
+      //
+      // Shallow copy the user provided options so that headers can be changed
+      // without mutating the original object.
+      //
+      options = { ...options, headers: {} };
+
+      if (headers) {
+        for (const [key, value] of Object.entries(headers)) {
+          options.headers[key.toLowerCase()] = value;
+        }
+      }
+    } else if (parsedUrl.host !== websocket._originalHost) {
+      //
+      // Match curl 7.77.0 behavior and drop the following headers. These
+      // headers are also dropped when following a redirect to a subdomain.
+      //
+      delete opts.headers.authorization;
+      delete opts.headers.cookie;
+      delete opts.headers.host;
+      opts.auth = undefined;
+    }
+
+    //
+    // Match curl 7.77.0 behavior and make the first `Authorization` header win.
+    // If the `Authorization` header is set, then there is nothing to do as it
+    // will take precedence.
+    //
+    if (opts.auth && !options.headers.authorization) {
+      options.headers.authorization =
+        'Basic ' + Buffer.from(opts.auth).toString('base64');
+    }
+  }
+
   let req = (websocket._req = get(opts));
 
   if (opts.timeout) {

Diff for: test/websocket.test.js

@@ -1140,6 +1140,119 @@ describe('WebSocket', () => {
         ws.on('close', () => done());
       });
     });
+
+    it('uses the first url userinfo when following redirects', (done) => {
+      const wss = new WebSocket.Server({ noServer: true, path: '/foo' });
+      const authorization = 'Basic Zm9vOmJhcg==';
+
+      server.once('upgrade', (req, socket) => {
+        socket.end('HTTP/1.1 302 Found\r\nLocation: /foo\r\n\r\n');
+        server.once('upgrade', (req, socket, head) => {
+          wss.handleUpgrade(req, socket, head, (ws, req) => {
+            assert.strictEqual(req.headers.authorization, authorization);
+            ws.close();
+          });
+        });
+      });
+
+      const port = server.address().port;
+      const ws = new WebSocket(`ws://foo:bar@localhost:${port}`, {
+        followRedirects: true
+      });
+
+      assert.strictEqual(ws._req.getHeader('Authorization'), authorization);
+
+      ws.on('close', (code) => {
+        assert.strictEqual(code, 1005);
+        assert.strictEqual(ws.url, `ws://foo:bar@localhost:${port}/foo`);
+        assert.strictEqual(ws._redirects, 1);
+
+        wss.close(done);
+      });
+    });
+
+    describe('When the redirect host is different', () => {
+      it('drops the `auth` option', (done) => {
+        const wss = new WebSocket.Server({ port: 0 }, () => {
+          const port = wss.address().port;
+
+          server.once('upgrade', (req, socket) => {
+            socket.end(
+              `HTTP/1.1 302 Found\r\nLocation: ws://localhost:${port}/\r\n\r\n`
+            );
+          });
+
+          const ws = new WebSocket(`ws://localhost:${server.address().port}`, {
+            auth: 'foo:bar',
+            followRedirects: true
+          });
+
+          assert.strictEqual(
+            ws._req.getHeader('Authorization'),
+            'Basic Zm9vOmJhcg=='
+          );
+
+          ws.on('close', (code) => {
+            assert.strictEqual(code, 1005);
+            assert.strictEqual(ws.url, `ws://localhost:${port}/`);
+            assert.strictEqual(ws._redirects, 1);
+
+            wss.close(done);
+          });
+        });
+
+        wss.on('connection', (ws, req) => {
+          assert.strictEqual(req.headers.authorization, undefined);
+          ws.close();
+        });
+      });
+
+      it('drops the Authorization, Cookie, and Host headers', (done) => {
+        const wss = new WebSocket.Server({ port: 0 }, () => {
+          const port = wss.address().port;
+
+          server.once('upgrade', (req, socket) => {
+            socket.end(
+              `HTTP/1.1 302 Found\r\nLocation: ws://localhost:${port}/\r\n\r\n`
+            );
+          });
+
+          const ws = new WebSocket(`ws://localhost:${server.address().port}`, {
+            headers: {
+              Authorization: 'Basic Zm9vOmJhcg==',
+              Cookie: 'foo=bar',
+              Host: 'foo'
+            },
+            followRedirects: true
+          });
+
+          assert.strictEqual(
+            ws._req.getHeader('Authorization'),
+            'Basic Zm9vOmJhcg=='
+          );
+          assert.strictEqual(ws._req.getHeader('Cookie'), 'foo=bar');
+          assert.strictEqual(ws._req.getHeader('Host'), 'foo');
+
+          ws.on('close', (code) => {
+            assert.strictEqual(code, 1005);
+            assert.strictEqual(ws.url, `ws://localhost:${port}/`);
+            assert.strictEqual(ws._redirects, 1);
+
+            wss.close(done);
+          });
+        });
+
+        wss.on('connection', (ws, req) => {
+          assert.strictEqual(req.headers.authorization, undefined);
+          assert.strictEqual(req.headers.cookie, undefined);
+          assert.strictEqual(
+            req.headers.host,
+            `localhost:${wss.address().port}`
+          );
+          ws.close();
+        });
+      });
+    });
   });
 
   describe('Connection with query string', () => {