fix: fix zero-value problem in config override

config/config.go

@@ -365,7 +365,7 @@ type RawOverride struct {
 	Hostname     string            `yaml:"hostname" json:"hostname"`
 	Username     string            `yaml:"username" json:"username"`
 	ListStrategy ListMergeStrategy `yaml:"list-strategy" json:"list-strategy"`
-	Content      *RawConfig        `yaml:"content" json:"content"`
+	Content      map[string]any    `yaml:"content" json:"content"`
 }
 
 type RawConfig struct {

config/override.go

@@ -1,17 +1,19 @@
 package config
 
 import (
-	"dario.cat/mergo"
-	"fmt"
 	"github.com/metacubex/mihomo/log"
+	"gopkg.in/yaml.v3"
 	"os"
 	"os/user"
-	"reflect"
 	"runtime"
 )
 
 type ListMergeStrategy string
 
+// insert-front: 	[old slice] -> [new slice, old slice]
+// append: 			[old slice] -> [old slice, new slice]
+// override: 		[old slice] -> [new slice] (Default)
+
 const (
 	InsertFront ListMergeStrategy = "insert-front"
 	Append      ListMergeStrategy = "append"
@@ -19,44 +21,9 @@ const (
 	Default     ListMergeStrategy = ""
 )
 
-// overrideTransformer is to merge slices with give strategy instead of the default behavior
-// - insert-front: 	[old slice] -> [new slice, old slice]
-// - append: 		[old slice] -> [old slice, new slice]
-// - override: 		[old slice] -> [new slice] (Default)
-type overrideTransformer struct {
-	listStrategy ListMergeStrategy
-}
-
-func (t overrideTransformer) Transformer(typ reflect.Type) func(dst, src reflect.Value) error {
-	if typ.Kind() == reflect.Slice {
-		return func(dst, src reflect.Value) error {
-			if src.IsNil() || !dst.CanSet() {
-				return nil
-			}
-			if src.Kind() != reflect.Slice || dst.Kind() != reflect.Slice {
-				return nil
-			}
-			// merge slice according to strategy
-			switch t.listStrategy {
-			case InsertFront:
-				newSlice := reflect.AppendSlice(src, dst)
-				dst.Set(newSlice)
-			case Append:
-				newSlice := reflect.AppendSlice(dst, src)
-				dst.Set(newSlice)
-			case Override, Default:
-				dst.Set(src)
-			default:
-				return fmt.Errorf("unknown list override strategy: %s", t.listStrategy)
-			}
-			return nil
-		}
-	}
-	return nil
-}
-
 func ApplyOverride(rawCfg *RawConfig, overrides []RawOverride) error {
 	for id, override := range overrides {
+		// check override conditions
 		if override.OS != "" && override.OS != runtime.GOOS {
 			continue
 		}
@@ -84,12 +51,29 @@ func ApplyOverride(rawCfg *RawConfig, overrides []RawOverride) error {
 			}
 		}
 
-		// merge rawConfig override
-		err := mergo.Merge(rawCfg, *override.Content, mergo.WithTransformers(overrideTransformer{
-			listStrategy: override.ListStrategy,
-		}), mergo.WithOverride)
+		// marshal override content back to text
+		overrideContent, err := yaml.Marshal(override.Content)
 		if err != nil {
 			log.Errorln("Error when applying override #%v: %v", id, err)
+			continue
+		}
+
+		// unmarshal override content into rawConfig, with custom list merge strategy
+		switch override.ListStrategy {
+		case Append:
+			options := yaml.NewDecodeOptions().ListDecodeOption(yaml.ListDecodeAppend)
+			err = yaml.UnmarshalWith(options, overrideContent, rawCfg)
+		case InsertFront:
+			options := yaml.NewDecodeOptions().ListDecodeOption(yaml.ListDecodeInsertFront)
+			err = yaml.UnmarshalWith(options, overrideContent, rawCfg)
+		case Override, Default:
+			err = yaml.Unmarshal(overrideContent, rawCfg)
+		default:
+			log.Errorln("Bad list strategy in override #%v: %v", id, override.ListStrategy)
+		}
+		if err != nil {
+			log.Errorln("Error when applying override #%v: %v", id, err)
+			continue
 		}
 	}
 	return nil

config/override_test.go

@@ -36,6 +36,30 @@ override:
 		assert.Equal(t, "0.0.0.0:9090", cfg.Controller.ExternalController)
 	})
 
+	t.Run("override_zero_value_test", func(t *testing.T) {
+		config_file := `
+mixed-port: 7890
+ipv6: true
+log-level: debug
+allow-lan: true
+unified-delay: false
+tcp-concurrent: true
+external-controller: 127.0.0.1:9090
+default-nameserver:
+  - "223.5.5.5"
+override:
+  - content:
+      external-controller: ""
+      allow-lan: false`
+		rawCfg, err := UnmarshalRawConfig([]byte(config_file))
+		assert.NoError(t, err)
+		cfg, err := ParseRawConfig(rawCfg)
+		assert.NoError(t, err)
+		assert.Equal(t, log.DEBUG, cfg.General.LogLevel)
+		assert.Equal(t, false, cfg.General.AllowLan)
+		assert.Equal(t, "", cfg.Controller.ExternalController)
+	})
+
 	t.Run("add_new", func(t *testing.T) {
 		config_file := `
 mixed-port: 7890

go.mod

@@ -3,7 +3,6 @@ module github.com/metacubex/mihomo
 go 1.20
 
 require (
-	dario.cat/mergo v1.0.1
 	github.com/3andne/restls-client-go v0.1.6
 	github.com/bahlo/generic-list-go v0.2.0
 	github.com/coreos/go-iptables v0.8.0