Optimize Linux process finder

common/process/searcher_linux.go

@@ -4,33 +4,82 @@ package process
 
 import (
 	"context"
+	"errors"
 	"net/netip"
+	"syscall"
+	"time"
 
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-box/log"
+	E "github.com/sagernet/sing/common/exceptions"
 )
 
 var _ Searcher = (*linuxSearcher)(nil)
 
 type linuxSearcher struct {
-	logger log.ContextLogger
+	logger           log.ContextLogger
+	diagConns        [4]*socketDiagConn
+	processPathCache *uidProcessPathCache
 }
 
 func NewSearcher(config Config) (Searcher, error) {
-	return &linuxSearcher{config.Logger}, nil
+	searcher := &linuxSearcher{
+		logger:           config.Logger,
+		processPathCache: newUIDProcessPathCache(time.Second),
+	}
+	for _, family := range []uint8{syscall.AF_INET, syscall.AF_INET6} {
+		for _, protocol := range []uint8{syscall.IPPROTO_TCP, syscall.IPPROTO_UDP} {
+			searcher.diagConns[socketDiagConnIndex(family, protocol)] = newSocketDiagConn(family, protocol)
+		}
+	}
+	return searcher, nil
+}
+
+func (s *linuxSearcher) Close() error {
+	var errs []error
+	for _, conn := range s.diagConns {
+		if conn == nil {
+			continue
+		}
+		errs = append(errs, conn.Close())
+	}
+	return E.Errors(errs...)
 }
 
 func (s *linuxSearcher) FindProcessInfo(ctx context.Context, network string, source netip.AddrPort, destination netip.AddrPort) (*adapter.ConnectionOwner, error) {
-	inode, uid, err := resolveSocketByNetlink(network, source, destination)
+	inode, uid, err := s.resolveSocketByNetlink(network, source, destination)
 	if err != nil {
 		return nil, err
 	}
-	processPath, err := resolveProcessNameByProcSearch(inode, uid)
+	processInfo := &adapter.ConnectionOwner{
+		UserId: int32(uid),
+	}
+	processPath, err := s.processPathCache.findProcessPath(inode, uid)
 	if err != nil {
 		s.logger.DebugContext(ctx, "find process path: ", err)
+	} else {
+		processInfo.ProcessPath = processPath
 	}
-	return &adapter.ConnectionOwner{
-		UserId:      int32(uid),
-		ProcessPath: processPath,
-	}, nil
+	return processInfo, nil
+}
+
+func (s *linuxSearcher) resolveSocketByNetlink(network string, source netip.AddrPort, destination netip.AddrPort) (inode, uid uint32, err error) {
+	family, protocol, err := socketDiagSettings(network, source)
+	if err != nil {
+		return 0, 0, err
+	}
+	conn := s.diagConns[socketDiagConnIndex(family, protocol)]
+	if conn == nil {
+		return 0, 0, E.New("missing socket diag connection for family=", family, " protocol=", protocol)
+	}
+	if destination.IsValid() && source.Addr().BitLen() == destination.Addr().BitLen() {
+		inode, uid, err = conn.query(source, destination)
+		if err == nil {
+			return inode, uid, nil
+		}
+		if !errors.Is(err, ErrNotFound) {
+			return 0, 0, err
+		}
+	}
+	return querySocketDiagOnce(family, protocol, source)
 }