Support auth switch in change user flow

closes #1776

Changes.md

@@ -19,6 +19,7 @@ you spot any mistakes.
 * Add Amazon RDS GovCloud SSL certificates #1876
 * Add new error codes up to MySQL 5.7.21
 * Include connection ID in debug output
+* Support auth switch in change user flow #1776
 * Support Node.js 9.x
 * Support Node.js 10.x #2003 #2024 #2026 #2034
 * Update Amazon RDS SSL certificates

lib/protocol/Auth.js

@@ -2,6 +2,18 @@ var Buffer = require('safe-buffer').Buffer;
 var Crypto = require('crypto');
 var Auth   = exports;
 
+function auth(name, data, options) {
+  options = options || {};
+
+  switch (name) {
+    case 'mysql_native_password':
+      return Auth.token(options.password, data.slice(0, 20));
+    default:
+      return undefined;
+  }
+}
+Auth.auth = auth;
+
 function sha1(msg) {
   var hash = Crypto.createHash('sha1');
   hash.update(msg, 'binary');

lib/protocol/sequences/ChangeUser.js

@@ -15,6 +15,14 @@ function ChangeUser(options, callback) {
   this._currentConfig = options.currentConfig;
 }
 
+ChangeUser.prototype.determinePacket = function determinePacket(firstByte) {
+  switch (firstByte) {
+    case 0xfe: return Packets.AuthSwitchRequestPacket;
+    case 0xff: return Packets.ErrorPacket;
+    default: return undefined;
+  }
+};
+
 ChangeUser.prototype.start = function(handshakeInitializationPacket) {
   var scrambleBuff = handshakeInitializationPacket.scrambleBuff();
   scrambleBuff     = Auth.token(this._password, scrambleBuff);
@@ -34,6 +42,24 @@ ChangeUser.prototype.start = function(handshakeInitializationPacket) {
   this.emit('packet', packet);
 };
 
+ChangeUser.prototype['AuthSwitchRequestPacket'] = function (packet) {
+  var name = packet.authMethodName;
+  var data = Auth.auth(name, packet.authMethodData, {
+    password: this._password
+  });
+
+  if (data !== undefined) {
+    this.emit('packet', new Packets.AuthSwitchResponsePacket({
+      data: data
+    }));
+  } else {
+    var err   = new Error('MySQL is requesting the ' + name + ' authentication method, which is not supported.');
+    err.code  = 'UNSUPPORTED_AUTH_METHOD';
+    err.fatal = true;
+    this.end(err);
+  }
+};
+
 ChangeUser.prototype['ErrorPacket'] = function(packet) {
   var err = this._packetToError(packet);
   err.fatal = true;

lib/protocol/sequences/Handshake.js

@@ -34,20 +34,19 @@ Handshake.prototype.determinePacket = function determinePacket(firstByte, parser
 };
 
 Handshake.prototype['AuthSwitchRequestPacket'] = function (packet) {
-  if (packet.authMethodName === 'mysql_native_password') {
-    var challenge = packet.authMethodData.slice(0, 20);
+  var name = packet.authMethodName;
+  var data = Auth.auth(name, packet.authMethodData, {
+    password: this._config.password
+  });
 
+  if (data !== undefined) {
     this.emit('packet', new Packets.AuthSwitchResponsePacket({
-      data: Auth.token(this._config.password, challenge)
+      data: data
     }));
   } else {
-    var err = new Error(
-      'MySQL is requesting the ' + packet.authMethodName + ' authentication method, which is not supported.'
-    );
-
-    err.code = 'UNSUPPORTED_AUTH_METHOD';
+    var err   = new Error('MySQL is requesting the ' + name + ' authentication method, which is not supported.');
+    err.code  = 'UNSUPPORTED_AUTH_METHOD';
     err.fatal = true;
-
     this.end(err);
   }
 };

test/unit/connection/test-change-user-auth-switch-unknown.js

@@ -0,0 +1,40 @@
+var assert     = require('assert');
+var Buffer     = require('safe-buffer').Buffer;
+var common     = require('../../common');
+var connection = common.createConnection({
+  port     : common.fakeServerPort,
+  user     : 'user_1',
+  password : 'pass_1'
+});
+
+var server = common.createFakeServer();
+
+server.listen(common.fakeServerPort, function(err) {
+  assert.ifError(err);
+
+  connection.query('SELECT CURRENT_USER()', function (err, result) {
+    assert.ifError(err);
+    assert.strictEqual(result[0]['CURRENT_USER()'], 'user_1@localhost');
+
+    connection.changeUser({user: 'user_2', password: 'pass_2'}, function (err) {
+      assert.ok(err);
+      assert.equal(err.code, 'UNSUPPORTED_AUTH_METHOD');
+      assert.equal(err.fatal, true);
+      assert.ok(/foo_plugin_password/.test(err.message));
+
+      connection.destroy();
+      server.destroy();
+    });
+  });
+});
+
+server.on('connection', function (incomingConnection) {
+  incomingConnection.on('changeUser', function () {
+    this.authSwitchRequest({
+      authMethodName : 'foo_plugin_password',
+      authMethodData : Buffer.alloc(0)
+    });
+  });
+
+  incomingConnection.handshake();
+});

test/unit/connection/test-change-user-auth-switch.js

@@ -0,0 +1,45 @@
+var assert     = require('assert');
+var Crypto     = require('crypto');
+var common     = require('../../common');
+var connection = common.createConnection({
+  port     : common.fakeServerPort,
+  user     : 'user_1',
+  password : 'pass_1'
+});
+
+var random = Crypto.pseudoRandomBytes || Crypto.randomBytes; // Depends on node.js version
+var server = common.createFakeServer();
+
+server.listen(common.fakeServerPort, function(err) {
+  assert.ifError(err);
+
+  connection.query('SELECT CURRENT_USER()', function (err, result) {
+    assert.ifError(err);
+    assert.strictEqual(result[0]['CURRENT_USER()'], 'user_1@localhost');
+
+    connection.changeUser({user: 'user_2', password: 'pass_2'}, function (err) {
+      assert.ifError(err);
+      connection.destroy();
+      server.destroy();
+    });
+  });
+});
+
+server.on('connection', function (incomingConnection) {
+  random(20, function (err, scramble) {
+    assert.ifError(err);
+
+    incomingConnection.on('authSwitchResponse', function (packet) {
+      this._sendAuthResponse(packet.data, common.Auth.token('pass_2', scramble));
+    });
+
+    incomingConnection.on('changeUser', function () {
+      this.authSwitchRequest({
+        authMethodName : 'mysql_native_password',
+        authMethodData : scramble
+      });
+    });
+
+    incomingConnection.handshake();
+  });
+});