fix #121. Db user authentication shouldn't fall back to cluster admin authentication

src/coordinator/coordinator.go

@@ -603,7 +603,7 @@ func (self *CoordinatorImpl) DropDatabase(user common.User, db string) error {
 func (self *CoordinatorImpl) AuthenticateDbUser(db, username, password string) (common.User, error) {
 	dbUsers := self.clusterConfiguration.dbUsers[db]
 	if dbUsers == nil || dbUsers[username] == nil {
-		return self.AuthenticateClusterAdmin(username, password)
+		return nil, common.NewAuthorizationError("Invalid username/password")
 	}
 	user := dbUsers[username]
 	if user.isValidPwd(password) {

src/integration/benchmark_test.go

@@ -251,6 +251,16 @@ func (self *IntegrationSuite) TestMedians(c *C) {
 	c.Assert(data[0].Points[1][1], Equals, 70.0)
 }
 
+func (self *IntegrationSuite) TestDbUserAuthentication(c *C) {
+	resp, err := http.Get("http://localhost:8086/db/db1/authenticate?u=root&p=root")
+	c.Assert(err, IsNil)
+	c.Assert(resp.StatusCode, Equals, http.StatusUnauthorized)
+
+	resp, err = http.Get("http://localhost:8086/db/db2/authenticate?u=root&p=root")
+	c.Assert(err, IsNil)
+	c.Assert(resp.StatusCode, Equals, http.StatusUnauthorized)
+}
+
 func (self *IntegrationSuite) TestArithmeticOperations(c *C) {
 	queries := map[string][9]float64{
 		"select input + output from test_arithmetic_3.0;":       [9]float64{1, 2, 3, 4, 5, 9, 6, 7, 13},