refactor the error handling and optimize the heap allocation

config/config.go

@@ -18,10 +18,11 @@ package config
 
 import (
 	"fmt"
-	"gitea.suyono.dev/suyono/netbounce/abstract"
 	"maps"
 	"slices"
 
+	"gitea.suyono.dev/suyono/netbounce/abstract"
+
 	"github.com/spf13/viper"
 )
 
@@ -83,6 +84,10 @@ func GetConnection(name string) (abstract.ConnectionConfig, error) {
 
 		tcp.Name = name
 		tcp.Type = abstract.TCP
+		module := tcpModule{config: tcp}
+		if err = module.Validate(); err != nil {
+			return nil, fmt.Errorf("tcp config: %w", err)
+		}
 		return tcpModule{config: tcp}, nil
 	default:
 		return nil, fmt.Errorf("connection %s: invalid connection type: %s", name, configType)

config/tcp.go

@@ -23,11 +23,13 @@ import (
 )
 
 type tcpConfig struct {
-	Name      string                  `mapstructure:"-,"`
-	Type      abstract.ConnectionType `mapstructure:"-,"`
-	Listen    string                  `mapstructure:"listen"`
-	Backend   string                  `mapstructure:"backend"`
-	KeepAlive bool                    `mapstructure:"keepalive,false"`
+	Name       string                  `mapstructure:"-,"`
+	Type       abstract.ConnectionType `mapstructure:"-,"`
+	Listen     string                  `mapstructure:"listen"`
+	Backend    string                  `mapstructure:"backend"`
+	KeepAlive  bool                    `mapstructure:"keepalive,false"`
+	ReadRetry  int                     `mapstructure:"read-retry,5"`
+	WriteRetry int                     `mapstructure:"write-retry,5"`
 }
 
 type tcpModule struct {
@@ -62,3 +64,19 @@ func (t tcpModule) AsUDP() abstract.UDPConnectionConfig {
 	panic(fmt.Errorf("not UDP"))
 	// return nil
 }
+
+func (t tcpModule) ReadRetry() int {
+	return t.config.ReadRetry
+}
+
+func (t tcpModule) WriteRetry() int {
+	return t.config.WriteRetry
+}
+
+func (t tcpModule) Validate() error {
+	if t.ReadRetry() <= 0 || t.WriteRetry() <= 0 {
+		return fmt.Errorf("invalid retry config value")
+	}
+
+	return nil
+}