finish transport listener

transport/internet/domainsocket/listener.go

@@ -5,45 +5,149 @@ import (
 	"net"
 	"os"
 	"syscall"
+	"time"
+
+	"v2ray.com/core/common/bitmask"
 )
 
 type Listener struct {
 	ln           net.Listener
-	listenerChan <-chan net.Conn
+	listenerChan chan<- net.Conn
 	ctx          context.Context
 	path         string
-	lockfile     os.File
+	lockfile     *os.File
+	state        bitmask.Byte
+	cancal       func()
 }
 
+const (
+	STATE_UNDEFINED   = 0
+	STATE_INITIALIZED = 1 << iota
+	STATE_LOWERUP     = 1 << iota
+	STATE_UP          = 1 << iota
+	STATE_TAINT       = 1 << iota
+)
+
 func ListenDS(ctx context.Context, path string) (*Listener, error) {
 
-	vln := &Listener{path: path}
+	vln := &Listener{path: path, state: STATE_INITIALIZED, ctx: ctx}
 	return vln, nil
 }
 
 func (ls *Listener) Down() error {
-	err := ls.ln.Close()
-	if err != nil {
-		newError(err).AtDebug().WriteToLog()
+	var err error
+	if !ls.state.Has(STATE_LOWERUP | STATE_UP) {
+		err = newError(ls.state).Base(newError("Invalid State:Down"))
+		if ___DEBUG_PANIC_WHEN_ENCOUNTED_IMPOSSIBLE_ERROR {
+			panic(err)
+		}
+		return err
 	}
-	return err
+
+	ls.cancal()
+	closeerr := ls.ln.Close()
+	var lockerr error
+	if isUnixDomainSocketFileSystemBased(ls.path) {
+		lockerr = giveupLock(ls.lockfile)
+	}
+	if closeerr != nil && lockerr != nil {
+		if ___DEBUG_PANIC_WHEN_ERROR_UNPROPAGATEABLE {
+			panic(closeerr.Error() + lockerr.Error())
+		}
+	}
+
+	if closeerr != nil {
+		return newError("Cannot Close Unix domain socket listener").Base(closeerr)
+	}
+	if lockerr != nil {
+		return newError("Cannot release lock for Unix domain socket listener").Base(lockerr)
+	}
+	ls.state.Clear(STATE_LOWERUP | STATE_UP)
+	return nil
 }
 
-//Setup systen level Listener
+//LowerUP Setup systen level Listener
 func (ls *Listener) LowerUP() error {
+	var err error
+
+	if !ls.state.Has(STATE_INITIALIZED) || ls.state.Has(STATE_LOWERUP) {
+		err = newError(ls.state).Base(newError("Invalid State:LowerUP"))
+		if ___DEBUG_PANIC_WHEN_ENCOUNTED_IMPOSSIBLE_ERROR {
+			panic(err)
+		}
+		return err
+	}
 
 	if isUnixDomainSocketFileSystemBased(ls.path) && !___DEBUG_IGNORE_FLOCK {
+		ls.lockfile, err = acquireLock(ls.path + ".lock")
+		if err != nil {
+			newError(err).AtDebug().WriteToLog()
+			return newError("Unable to acquire lock for filesystem based unix domain socket").Base(err)
+		}
+	}
 
+	err = cleansePath(ls.path)
+	if err != nil {
+		return newError("Unable to cleanse path for the creation of unix domain socket").Base(err)
 	}
 
 	addr := new(net.UnixAddr)
 	addr.Name = ls.path
 	addr.Net = "unix"
 	li, err := net.ListenUnix("unix", addr)
+	ls.ln = li
 	if err != nil {
-		return err
+		return newError("Unable to listen unix domain socket").Base(err)
 	}
 
+	ls.state.Set(STATE_LOWERUP)
+
+	return nil
+}
+
+func (ls *Listener) UP(listener chan<- net.Conn, allowkick bool) error {
+	var err error
+	if !ls.state.Has(STATE_INITIALIZED|STATE_LOWERUP) || (ls.state.Has(STATE_UP) && !allowkick) {
+		err = newError(ls.state).Base(newError("Invalid State:UP"))
+		if ___DEBUG_PANIC_WHEN_ENCOUNTED_IMPOSSIBLE_ERROR {
+			panic(err)
+		}
+		return err
+	}
+	ls.listenerChan = listener
+	if ls.state.Has(STATE_UP) {
+		cctx, cancel := context.WithCancel(ls.ctx)
+		ls.cancal = cancel
+		go ls.uploop(cctx)
+	}
+	return nil
+}
+
+func (ls *Listener) uploop(cctx context.Context) {
+	var lasterror error
+	errortolerance := 5
+	for {
+		if cctx.Err() != nil {
+			return
+		}
+		conn, err := ls.ln.Accept()
+
+		if err != nil {
+			newError("Cannot Accept socket from listener").Base(err).AtDebug().WriteToLog()
+			if err == lasterror {
+				errortolerance--
+				if errortolerance == 0 {
+					newError("unix domain socket melt down as the error is repeating").Base(err).AtError().WriteToLog()
+					ls.cancal()
+				}
+				newError("unix domain socket listener is throttling accept as the error is repeating").Base(err).AtError().WriteToLog()
+				time.Sleep(time.Second * 5)
+			}
+			lasterror = err
+		}
+
+		ls.listenerChan <- conn
+	}
 }
 
 func isUnixDomainSocketFileSystemBased(path string) bool {
@@ -51,7 +155,7 @@ func isUnixDomainSocketFileSystemBased(path string) bool {
 	return path[0] != 0
 }
 
-func AcquireLock(lockfilepath string) (*os.File, error) {
+func acquireLock(lockfilepath string) (*os.File, error) {
 	f, err := os.Create(lockfilepath)
 	if err != nil {
 		newError(err).AtDebug().WriteToLog()
@@ -69,6 +173,37 @@ func AcquireLock(lockfilepath string) (*os.File, error) {
 		}
 		return nil, err
 	}
+	return nil, err
+}
+
+func giveupLock(locker *os.File) error {
+	err := syscall.Flock(int(locker.Fd()), syscall.LOCK_UN)
+	if err != nil {
+		closeerr := locker.Close()
+		if err != nil {
+			if ___DEBUG_PANIC_WHEN_ERROR_UNPROPAGATEABLE {
+				panic(closeerr)
+			}
+			newError(closeerr).AtDebug().WriteToLog()
+		}
+		newError(err).AtDebug().WriteToLog()
+		return err
+	}
+	closeerr := locker.Close()
+	if closeerr != nil {
+		newError(closeerr).AtDebug().WriteToLog()
+		return closeerr
+	}
+	return closeerr
+}
+
+func cleansePath(path string) error {
+	_, err := os.Stat(path)
+	if err == os.ErrNotExist {
+		return nil
+	}
+	err = os.Remove(path)
+	return err
 }
 
 //DEBUG CONSTS