Fix Connection timeout

core/cmd/dragontcp-client/bp.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"net"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"dragontcp/internal/cover"
@@ -163,20 +164,29 @@ func (l *bpLane) single(mode byte, sid wire.SessionID, seq uint64, payload []byt
 	var lastErr error
 	for attempt := 0; attempt < 2; attempt++ {
 		if err := l.ensureLocked(); err != nil {
+			if isTransportTimeout(err) {
+				return 0, nil, err
+			}
 			lastErr = err
 			continue
 		}
 		reused := l.pc.requests > 0
 		_ = l.pc.conn.SetDeadline(time.Now().Add(timeout))
 		if err := writeBPRequest(l.pc.conn, mode, sid, seq, payload, downloadHint, l.coverProfile.HeaderMask, l.coverProfile.Clear); err != nil {
-			lastErr = err
 			l.transportFailureLocked(reused)
+			if isTransportTimeout(err) {
+				return 0, nil, err
+			}
+			lastErr = err
 			continue
 		}
 		status, body, err := readBPResponse(l.pc.conn, sid, mode, seq, l.coverProfile.HeaderMask, l.coverProfile.Clear)
 		if err != nil {
-			lastErr = err
 			l.transportFailureLocked(reused)
+			if isTransportTimeout(err) {
+				return 0, nil, err
+			}
+			lastErr = err
 			continue
 		}
 		l.pc.requests++
@@ -222,14 +232,20 @@ func (l *bpLane) download(sid wire.SessionID, offset uint64, maxChunk, count int
 	var lastErr error
 	for attempt := 0; attempt < 2; attempt++ {
 		if err := l.ensureLocked(); err != nil {
+			if isTransportTimeout(err) {
+				return nil, 0, err
+			}
 			lastErr = err
 			continue
 		}
 		reused := l.pc.requests > 0
 		_ = l.pc.conn.SetDeadline(time.Now().Add(timeout))
 		if err := writeBPRequest(l.pc.conn, mode, sid, offset, payload, hint, l.coverProfile.HeaderMask, l.coverProfile.Clear); err != nil {
-			lastErr = err
 			l.transportFailureLocked(reused)
+			if isTransportTimeout(err) {
+				return nil, 0, err
+			}
+			lastErr = err
 			continue
 		}
 
@@ -238,8 +254,11 @@ func (l *bpLane) download(sid wire.SessionID, offset uint64, maxChunk, count int
 		for i := 0; i < responses; i++ {
 			status, body, err := readBPResponse(l.pc.conn, sid, mode, offset, l.coverProfile.HeaderMask, l.coverProfile.Clear)
 			if err != nil {
-				lastErr = err
 				l.transportFailureLocked(reused)
+				if isTransportTimeout(err) {
+					return nil, 0, err
+				}
+				lastErr = err
 				goto retry
 			}
 			lastStatus = status
@@ -292,6 +311,7 @@ type bpConn struct {
 	pipeline       int
 
 	closeOnce sync.Once
+	dead      atomic.Bool
 }
 
 func openBPTunnel(serverAddr, token, targetHost string, targetPort int, opts chunkClientOptions) (net.Conn, error) {
@@ -385,6 +405,9 @@ func (c *bpConn) fillReadBuffer() error {
 		if c.consumedOffset > c.lastAck {
 			status, body, err := c.downloadLane.single(bpModeACK, c.sid, c.consumedOffset, nil, 0)
 			if err != nil {
+				if isTransportTimeout(err) {
+					c.dead.Store(true)
+				}
 				return err
 			}
 			if status == wire.StatusError {
@@ -402,6 +425,10 @@ func (c *bpConn) fillReadBuffer() error {
 		}
 		data, status, err := c.downloadLane.download(c.sid, c.downloadOffset, chunk, count)
 		if err != nil {
+			if isTransportTimeout(err) {
+				c.dead.Store(true)
+				return err
+			}
 			old, next := c.downSizer.FailureReason(chunk, err)
 			if old == next && next == c.opts.minSize {
 				return err
@@ -462,6 +489,10 @@ func (c *bpConn) Write(p []byte) (int, error) {
 		n := minInt(size, len(p))
 		status, body, err := c.uploadLane.single(bpModeUpload, c.sid, c.upOffset+2, p[:n], 0)
 		if err != nil {
+			if isTransportTimeout(err) {
+				c.dead.Store(true)
+				return total, err
+			}
 			old, next := c.upSizer.FailureReason(size, err)
 			if old == next && next == c.opts.minSize {
 				return total, err
@@ -485,7 +516,11 @@ func (c *bpConn) Write(p []byte) (int, error) {
 
 func (c *bpConn) Close() error {
 	c.closeOnce.Do(func() {
-		_, _, _ = c.downloadLane.single(bpModeACK, c.sid, c.consumedOffset, bpCloseMagic[:], 0)
+		// A timeout is a hard tunnel boundary. Do not create a fresh physical
+		// connection only to close a session that has already been abandoned.
+		if !c.dead.Load() {
+			_, _, _ = c.downloadLane.single(bpModeACK, c.sid, c.consumedOffset, bpCloseMagic[:], 0)
+		}
 		c.uploadLane.Close()
 		c.downloadLane.Close()
 	})