fix: in for defer close (#2411)

Resource leakage may occur. Call 'defer' in the 'for' loop.
case: https://go.dev/doc/effective_go#defer

contrib/log/fluent/fluent_test.go

@@ -11,18 +11,23 @@ import (
 )
 
 func TestMain(m *testing.M) {
+	listener := func(ln net.Listener) {
+		conn, err := ln.Accept()
+		if err != nil {
+			return
+		}
+		defer conn.Close()
+		_, err = io.ReadAll(conn)
+		if err != nil {
+			return
+		}
+	}
+
 	if ln, err := net.Listen("tcp", ":24224"); err == nil {
 		defer ln.Close()
 		go func() {
 			for {
-				conn, err := ln.Accept()
-				if err != nil {
-					return
-				}
-				defer conn.Close()
-				if _, err = io.ReadAll(conn); err != nil {
-					continue
-				}
+				listener(ln)
 			}
 		}()
 	}

contrib/registry/eureka/client.go

@@ -307,39 +307,50 @@ func (e *Client) buildAPI(currentTimes int, params ...string) string {
 	return strings.Join(params, "/")
 }
 
-func (e *Client) do(ctx context.Context, method string, params []string, input io.Reader, output interface{}) error {
-	for i := 0; i < e.maxRetry; i++ {
-		request, err := http.NewRequest(method, e.buildAPI(i, params...), input)
+func (e *Client) request(ctx context.Context, method string, params []string, input io.Reader, output interface{}, i int) (bool, error) {
+	request, err := http.NewRequestWithContext(ctx, method, e.buildAPI(i, params...), input)
+	if err != nil {
+		return false, err
+	}
+	request.Header.Add("User-Agent", "go-eureka-client")
+	request.Header.Add("Accept", "application/json;charset=UTF-8")
+	request.Header.Add("Content-Type", "application/json;charset=UTF-8")
+	resp, err := e.client.Do(request)
+	if err != nil {
+		return true, err
+	}
+	defer func() {
+		_, _ = io.Copy(io.Discard, resp.Body)
+		_ = resp.Body.Close()
+	}()
+
+	if output != nil && resp.StatusCode/100 == 2 {
+		data, err := io.ReadAll(resp.Body)
 		if err != nil {
-			return err
+			return false, err
 		}
-		request = request.WithContext(ctx)
-		request.Header.Add("User-Agent", "go-eureka-client")
-		request.Header.Add("Accept", "application/json;charset=UTF-8")
-		request.Header.Add("Content-Type", "application/json;charset=UTF-8")
-		resp, err := e.client.Do(request)
+		err = json.Unmarshal(data, output)
 		if err != nil {
-			continue
-		}
-		defer func() {
-			_, _ = io.Copy(io.Discard, resp.Body)
-			resp.Body.Close()
-		}()
-
-		if output != nil && resp.StatusCode/100 == 2 {
-			data, err := io.ReadAll(resp.Body)
-			if err != nil {
-				return err
-			}
-			if err = json.Unmarshal(data, output); err != nil {
-				return err
-			}
+			return false, err
 		}
+	}
 
-		if resp.StatusCode >= http.StatusBadRequest {
-			return fmt.Errorf("response Error %d", resp.StatusCode)
-		}
+	if resp.StatusCode >= http.StatusBadRequest {
+		return false, fmt.Errorf("response Error %d", resp.StatusCode)
+	}
 
+	return false, nil
+}
+
+func (e *Client) do(ctx context.Context, method string, params []string, input io.Reader, output interface{}) error {
+	for i := 0; i < e.maxRetry; i++ {
+		retry, err := e.request(ctx, method, params, input, output, i)
+		if retry {
+			continue
+		}
+		if err != nil {
+			return err
+		}
 		return nil
 	}
 	return fmt.Errorf("retry after %d times", e.maxRetry)