fix: kcp 协议内部日志细节

cmd/internal/transport/kcp_packet_conn_linux.go

@@ -17,6 +17,7 @@ type kcpPendingPacketDebug struct {
 	remoteAddr  net.Addr
 	packetBytes int
 	kcpConv     *uint32
+	segments    []KCPPacketDebugSegment
 	timestamps  map[string]int64
 }
 
@@ -75,13 +76,15 @@ func (c *platformKCPPacketConn) ReadFrom(p []byte) (int, net.Addr, error) {
 		}
 
 		if rxTimestamp > 0 {
+			kcpConv, segments := parseKCPPacketMetadata(p[:n])
 			c.logKCPPacketDebugRecord(c.newKCPPacketDebugRecord(
 				latencylog.EventBRXSoftware,
 				addr,
 				n,
 				rxTimestamp,
 				nil,
-				parseKCPConversationID(p[:n]),
+				kcpConv,
+				segments,
 			))
 		}
 
@@ -102,7 +105,11 @@ func (c *platformKCPPacketConn) WriteTo(p []byte, addr net.Addr) (int, error) {
 		return 0, fmt.Errorf("transport: kcp packet write target must be UDPAddr, got %T", addr)
 	}
 
-	expectedTXID := c.nextExpectedTXID()
+	// Reserve the local txID before the send so an immediately-arriving errqueue
+	// event can still find its pending record. If the send never succeeds, roll
+	// the reservation back to keep the local txID mirror aligned with the kernel.
+	kcpConv, segments := parseKCPPacketMetadata(p)
+	expectedTXID := c.reservePendingTX(udpAddr, len(p), kcpConv, segments)
 	for {
 		err := c.sendmsgRaw(p, udpAddr)
 		if err != nil {
@@ -110,10 +117,10 @@ func (c *platformKCPPacketConn) WriteTo(p []byte, addr net.Addr) (int, error) {
 				time.Sleep(linuxDataPollInterval)
 				continue
 			}
+			c.rollbackPendingTX(expectedTXID)
 			return 0, err
 		}
 
-		c.storePendingTX(expectedTXID, udpAddr, len(p), parseKCPConversationID(p))
 		return len(p), nil
 	}
 }
@@ -247,6 +254,7 @@ func (c *platformKCPPacketConn) collectTXErrqueueLoop() {
 			event.TSUnixNano,
 			&udpTxID,
 			record.kcpConv,
+			record.segments,
 		))
 
 		if complete {
@@ -281,25 +289,31 @@ func (c *platformKCPPacketConn) recvTXErrqueueOnce() (txTimestampEvent, error) {
 	return event, nil
 }
 
-func (c *platformKCPPacketConn) nextExpectedTXID() uint32 {
+func (c *platformKCPPacketConn) reservePendingTX(remoteAddr net.Addr, packetBytes int, kcpConv *uint32, segments []KCPPacketDebugSegment) uint32 {
 	c.pendingMu.Lock()
 	defer c.pendingMu.Unlock()
 
-	next := c.nextTXID
+	txID := c.nextTXID
 	c.nextTXID++
-	return next
-}
-
-func (c *platformKCPPacketConn) storePendingTX(txID uint32, remoteAddr net.Addr, packetBytes int, kcpConv *uint32) {
-	c.pendingMu.Lock()
-	defer c.pendingMu.Unlock()
-
 	c.pendingTX[txID] = kcpPendingPacketDebug{
 		remoteAddr:  remoteAddr,
 		packetBytes: packetBytes,
 		kcpConv:     kcpConv,
+		segments:    append([]KCPPacketDebugSegment(nil), segments...),
 		timestamps:  make(map[string]int64, 2),
 	}
+
+	return txID
+}
+
+func (c *platformKCPPacketConn) rollbackPendingTX(txID uint32) {
+	c.pendingMu.Lock()
+	defer c.pendingMu.Unlock()
+
+	delete(c.pendingTX, txID)
+	if c.nextTXID == txID+1 {
+		c.nextTXID = txID
+	}
 }
 
 func (c *platformKCPPacketConn) recordPendingTXEvent(event txTimestampEvent) (*kcpPendingPacketDebug, bool) {