Fix the numeric overflow bug of ping response data in the cluster module

sentinel-cluster/sentinel-cluster-client-default/pom.xml

@@ -53,5 +53,10 @@
             <artifactId>mockito-core</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>

sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/PingResponseDataDecoder.java

@@ -27,9 +27,14 @@ public class PingResponseDataDecoder implements EntityDecoder<ByteBuf, Integer>
 
     @Override
     public Integer decode(ByteBuf source) {
-        if (source.readableBytes() >= 1) {
+        int size = source.readableBytes();
+        if (size == 1) {
+            // Compatible with old version (< 1.7.0).
             return (int) source.readByte();
         }
+        if (size >= 4) {
+            return source.readInt();
+        }
         return -1;
     }
 }

sentinel-cluster/sentinel-cluster-client-default/src/test/java/com/alibaba/csp/sentinel/cluster/client/codec/data/PingResponseDataDecoderTest.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.csp.sentinel.cluster.client.codec.data;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Eric Zhao
+ */
+public class PingResponseDataDecoderTest {
+
+    @Test
+    public void testDecodePingResponseData() {
+        ByteBuf buf = Unpooled.buffer();
+        PingResponseDataDecoder decoder = new PingResponseDataDecoder();
+
+        int big = Integer.MAX_VALUE;
+        buf.writeInt(big);
+        assertThat(decoder.decode(buf)).isEqualTo(big);
+
+        byte small = 12;
+        buf.writeByte(small);
+        assertThat(decoder.decode(buf)).isEqualTo(small);
+
+        buf.release();
+    }
+}

sentinel-cluster/sentinel-cluster-server-default/pom.xml

@@ -52,5 +52,10 @@
             <artifactId>mockito-core</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>

sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/server/codec/data/PingResponseDataWriter.java

@@ -31,6 +31,6 @@ public void writeTo(Integer entity, ByteBuf target) {
         if (entity == null || target == null) {
             return;
         }
-        target.writeByte(entity);
+        target.writeInt(entity);
     }
 }

sentinel-cluster/sentinel-cluster-server-default/src/test/java/com/alibaba/csp/sentinel/cluster/server/codec/data/PingResponseDataWriterTest.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 1999-2019 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.csp.sentinel.cluster.server.codec.data;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Test cases for {@link PingResponseDataWriter}.
+ *
+ * @author Eric Zhao
+ */
+public class PingResponseDataWriterTest {
+
+    @Test
+    public void testWritePingResponseAndParse() {
+        ByteBuf buf = Unpooled.buffer();
+        PingResponseDataWriter writer = new PingResponseDataWriter();
+
+        int small = 120;
+        writer.writeTo(small, buf);
+        assertThat(buf.readableBytes()).isGreaterThanOrEqualTo(4);
+        assertThat(buf.readInt()).isEqualTo(small);
+
+        int big = Integer.MAX_VALUE;
+        writer.writeTo(big, buf);
+        assertThat(buf.readableBytes()).isGreaterThanOrEqualTo(4);
+        assertThat(buf.readInt()).isEqualTo(big);
+
+        buf.release();
+    }
+}