Add clash persistence support

experimental/clashapi/cachefile/cache.go

@@ -0,0 +1,61 @@
+package cachefile
+
+import (
+	"os"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+
+	"go.etcd.io/bbolt"
+)
+
+var bucketSelected = []byte("selected")
+
+var _ adapter.ClashCacheFile = (*CacheFile)(nil)
+
+type CacheFile struct {
+	DB *bbolt.DB
+}
+
+func Open(path string) (*CacheFile, error) {
+	const fileMode = 0o666
+	options := bbolt.Options{Timeout: time.Second}
+	db, err := bbolt.Open(path, fileMode, &options)
+	switch err {
+	case bbolt.ErrInvalid, bbolt.ErrChecksum, bbolt.ErrVersionMismatch:
+		if err = os.Remove(path); err != nil {
+			break
+		}
+		db, err = bbolt.Open(path, 0o666, &options)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &CacheFile{db}, nil
+}
+
+func (c *CacheFile) LoadSelected(group string) string {
+	var selected string
+	c.DB.View(func(t *bbolt.Tx) error {
+		bucket := t.Bucket(bucketSelected)
+		if bucket == nil {
+			return nil
+		}
+		selectedBytes := bucket.Get([]byte(group))
+		if len(selectedBytes) > 0 {
+			selected = string(selectedBytes)
+		}
+		return nil
+	})
+	return selected
+}
+
+func (c *CacheFile) StoreSelected(group, selected string) error {
+	return c.DB.Batch(func(t *bbolt.Tx) error {
+		bucket, err := t.CreateBucketIfNotExists(bucketSelected)
+		if err != nil {
+			return err
+		}
+		return bucket.Put([]byte(group), []byte(selected))
+	})
+}

experimental/clashapi/server.go

@@ -14,6 +14,7 @@ import (
 	"github.com/sagernet/sing-box/common/json"
 	"github.com/sagernet/sing-box/common/urltest"
 	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/experimental/clashapi/cachefile"
 	"github.com/sagernet/sing-box/experimental/clashapi/trafficontrol"
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
@@ -38,9 +39,11 @@ type Server struct {
 	urlTestHistory *urltest.HistoryStorage
 	tcpListener    net.Listener
 	mode           string
+	storeSelected  bool
+	cacheFile      adapter.ClashCacheFile
 }
 
-func NewServer(router adapter.Router, logFactory log.ObservableFactory, options option.ClashAPIOptions) *Server {
+func NewServer(router adapter.Router, logFactory log.ObservableFactory, options option.ClashAPIOptions) (*Server, error) {
 	trafficManager := trafficontrol.NewManager()
 	chiRouter := chi.NewRouter()
 	server := &Server{
@@ -57,6 +60,17 @@ func NewServer(router adapter.Router, logFactory log.ObservableFactory, options
 	if server.mode == "" {
 		server.mode = "rule"
 	}
+	if options.StoreSelected {
+		cachePath := os.ExpandEnv(options.CacheFile)
+		if cachePath == "" {
+			cachePath = "cache.db"
+		}
+		cacheFile, err := cachefile.Open(cachePath)
+		if err != nil {
+			return nil, E.Cause(err, "open cache file")
+		}
+		server.cacheFile = cacheFile
+	}
 	cors := cors.New(cors.Options{
 		AllowedOrigins: []string{"*"},
 		AllowedMethods: []string{"GET", "POST", "PUT", "PATCH", "DELETE"},
@@ -89,7 +103,7 @@ func NewServer(router adapter.Router, logFactory log.ObservableFactory, options
 			})
 		})
 	}
-	return server
+	return server, nil
 }
 
 func (s *Server) Start() error {
@@ -113,9 +127,22 @@ func (s *Server) Close() error {
 		common.PtrOrNil(s.httpServer),
 		s.tcpListener,
 		s.trafficManager,
+		s.cacheFile,
 	)
 }
 
+func (s *Server) Mode() string {
+	return s.mode
+}
+
+func (s *Server) StoreSelected() bool {
+	return s.storeSelected
+}
+
+func (s *Server) CacheFile() adapter.ClashCacheFile {
+	return s.cacheFile
+}
+
 func (s *Server) RoutedConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext, matchedRule adapter.Rule) (net.Conn, adapter.Tracker) {
 	tracker := trafficontrol.NewTCPTracker(conn, s.trafficManager, castMetadata(metadata), s.router, matchedRule)
 	return tracker, tracker
@@ -126,10 +153,6 @@ func (s *Server) RoutedPacketConnection(ctx context.Context, conn N.PacketConn,
 	return tracker, tracker
 }
 
-func (s *Server) Mode() string {
-	return s.mode
-}
-
 func castMetadata(metadata adapter.InboundContext) trafficontrol.Metadata {
 	var inbound string
 	if metadata.Inbound != "" {