fix: memory leak in the HTTP tunnel module under extreme scenarios

httptunnel/server.go

@@ -21,13 +21,19 @@ import (
 )
 
 const RelayBufferSize = cipherstream.MaxCipherRelaySize
+const DefaultConnCount = 256
 
 type Server struct {
 	addr    string
 	timeout time.Duration
 
-	sync.Mutex
-	connMap     map[string][]net.Conn
+	sync.RWMutex
+	connMap map[string]*struct {
+		conns              []net.Conn
+		ch                 chan struct{}
+		timer              *time.Timer
+		isPushCloseRunning bool
+	}
 	connCh      chan net.Conn
 	closing     chan struct{}
 	pullWaiting map[string]chan struct{}
@@ -44,12 +50,17 @@ func NewServer(addr string, timeout time.Duration, tlsConfig *tls.Config) *Serve
 	}
 
 	return &Server{
-		addr:        addr,
-		timeout:     timeout,
-		connMap:     make(map[string][]net.Conn, 256),
+		addr:    addr,
+		timeout: timeout,
+		connMap: make(map[string]*struct {
+			conns              []net.Conn
+			ch                 chan struct{}
+			timer              *time.Timer
+			isPushCloseRunning bool
+		}, DefaultConnCount),
 		connCh:      make(chan net.Conn, 1),
 		closing:     make(chan struct{}, 1),
-		pullWaiting: make(map[string]chan struct{}, 256),
+		pullWaiting: make(map[string]chan struct{}, DefaultConnCount),
 		tlsConfig:   tlsConfig,
 		server:      server,
 	}
@@ -131,9 +142,9 @@ func (s *Server) pull(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	s.Lock()
-	conns := s.connMap[reqID]
-	s.Unlock()
+	s.RLock()
+	conns := s.connMap[reqID].conns
+	s.RUnlock()
 	log.Debug("[HTTP_TUNNEL_SERVER] pull", "uuid", reqID)
 
 	w.Header().Set("Content-Type", "application/json")
@@ -172,7 +183,7 @@ func (s *Server) pull(w http.ResponseWriter, r *http.Request) {
 		log.Warn("[HTTP_TUNNEL_SERVER] read from conn", "err", err)
 	}
 
-	s.pullClose(reqID)
+	s.pullCloseConn(reqID)
 	log.Info("[HTTP_TUNNEL_SERVER] Pull completed...", "uuid", reqID)
 }
 
@@ -222,16 +233,43 @@ func (s *Server) push(w http.ResponseWriter, r *http.Request) {
 	conns, ok := s.connMap[reqID]
 	if !ok {
 		conn1, conn2 := netpipe.Pipe(2*cipherstream.MaxPayloadSize, addr)
-		conns = []net.Conn{conn1, conn2}
+		conns = &struct {
+			conns              []net.Conn
+			ch                 chan struct{}
+			timer              *time.Timer
+			isPushCloseRunning bool
+		}{
+			conns: []net.Conn{conn1, conn2},
+			ch:    make(chan struct{}, 1),
+			timer: time.NewTimer(s.timeout),
+		}
 		s.connMap[reqID] = conns
 		s.connCh <- conn2
 	}
 	s.notifyPull(reqID)
 	s.Unlock()
 
+	defer func() {
+		s.Lock()
+		defer s.Unlock()
+
+		conns, ok := s.connMap[reqID]
+		if !ok {
+			return
+		}
+		timer := conns.timer
+		timer.Reset(s.timeout)
+		if conns.isPushCloseRunning {
+			return
+		}
+		conns.isPushCloseRunning = true
+
+		go s.pushCloseConn(reqID)
+	}()
+
 	if p.Payload == "" {
 		// client end push
-		_ = conns[0].(interface{ CloseWrite() error }).CloseWrite()
+		_ = conns.conns[0].(interface{ CloseWrite() error }).CloseWrite()
 		return
 	}
 	cipher, err := base64.StdEncoding.DecodeString(p.Payload)
@@ -241,7 +279,7 @@ func (s *Server) push(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if _, err = conns[0].Write(cipher); err != nil {
+	if _, err = conns.conns[0].Write(cipher); err != nil {
 		log.Warn("[HTTP_TUNNEL_SERVER] write local", "err", err)
 		writeServiceUnavailableError(w, "write local:"+err.Error())
 		return
@@ -250,12 +288,43 @@ func (s *Server) push(w http.ResponseWriter, r *http.Request) {
 	writeSuccess(w)
 }
 
-func (s *Server) pullClose(reqID string) {
+func (s *Server) pushCloseConn(reqID string) {
+	s.RLock()
+	conns, ok := s.connMap[reqID]
+	if !ok {
+		s.RUnlock()
+		return
+	}
+
+	timer := conns.timer
+	ch := conns.ch
+	s.RUnlock()
+
+	select {
+	case <-s.closing:
+	case <-timer.C:
+	case <-ch:
+	}
+
+	s.Lock()
+	defer s.Unlock()
+	s.closeConn(reqID)
+}
+
+func (s *Server) pullCloseConn(reqID string) {
 	s.Lock()
 	defer s.Unlock()
 
 	if conns, ok := s.connMap[reqID]; ok {
-		_ = conns[0].Close()
+		close(conns.ch)
+	}
+
+	s.closeConn(reqID)
+}
+
+func (s *Server) closeConn(reqID string) {
+	if conns, ok := s.connMap[reqID]; ok {
+		_ = conns.conns[0].Close()
 	}
 
 	s.connMap[reqID] = nil