fixed security bugfix #4941 , process auth failed

deployer/src/main/resources/canal_local.properties

@@ -5,8 +5,8 @@ canal.register.ip =
 canal.admin.manager = 127.0.0.1:8089
 canal.admin.port = 11110
 canal.admin.user = admin
-canal.admin.passwd = 4ACFE3202A5FF5CF467898FC58AAB1D615029441
+canal.admin.passwd =
 # admin auto register
 canal.admin.register.auto = true
 canal.admin.register.cluster =
-canal.admin.register.name = 
+canal.admin.register.name = 

server/src/main/java/com/alibaba/otter/canal/server/netty/handler/ClientAuthenticationHandler.java

@@ -56,12 +56,14 @@ public class ClientAuthenticationHandler extends SimpleChannelHandler {
                     byte[] errorBytes = NettyUtils.errorPacket(400,
                         MessageFormatter.format("auth failed for seed is null", clientAuth.getUsername()).getMessage());
                     NettyUtils.write(ctx.getChannel(), errorBytes, null);
+                    break;
                 }
 
                 if (!embeddedServer.auth(clientAuth.getUsername(), clientAuth.getPassword().toStringUtf8(), seed)) {
                     byte[] errorBytes = NettyUtils.errorPacket(400,
                         MessageFormatter.format("auth failed for user:{}", clientAuth.getUsername()).getMessage());
                     NettyUtils.write(ctx.getChannel(), errorBytes, null);
+                    break;
                 }
 
                 // 如果存在订阅信息