New

core/internal/xorchunk/chunk.go

@@ -19,6 +19,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"dragontcp/internal/cover"
 	"dragontcp/internal/protocol"
 )
 
@@ -57,6 +58,24 @@ type Options struct {
 	pollDelay      time.Duration
 	txnTimeout     time.Duration
 	tcpBuffer      int
+	headerMask     byte
+	coverProfile   cover.Profile
+}
+
+// WithHeaderMask returns a copy using one fixed frame-magic profile. The mask
+// is selected during startup discovery and remains unchanged for normal data.
+func (o Options) WithHeaderMask(mask byte) Options {
+	o.headerMask = mask
+	o.coverProfile = cover.Profile{}
+	return o
+}
+
+// WithCoverProfile returns a copy using a fixed startup-selected preface,
+// padding length, and frame mask.
+func (o Options) WithCoverProfile(profile cover.Profile) Options {
+	o.coverProfile = profile
+	o.headerMask = profile.HeaderMask
+	return o
 }
 
 func wireToken(token string) string {
@@ -219,17 +238,21 @@ type txnLane struct {
 	tcpBuffer      int
 	reconnectEvery int
 	timeout        time.Duration
+	headerMask     byte
+	coverProfile   cover.Profile
 	conn           net.Conn
 	count          int
 	closed         bool
 }
 
-func newTxnLane(serverAddr string, tcpBuffer, reconnectEvery int, timeout time.Duration) *txnLane {
+func newTxnLane(serverAddr string, tcpBuffer, reconnectEvery int, timeout time.Duration, headerMask byte, coverProfile cover.Profile) *txnLane {
 	return &txnLane{
 		serverAddr:     serverAddr,
 		tcpBuffer:      tcpBuffer,
 		reconnectEvery: reconnectEvery,
 		timeout:        timeout,
+		headerMask:     headerMask,
+		coverProfile:   coverProfile,
 	}
 }
 
@@ -262,6 +285,10 @@ func (l *txnLane) ensureConn() error {
 	if err != nil {
 		return err
 	}
+	if err := cover.WritePreface(conn, l.coverProfile); err != nil {
+		_ = conn.Close()
+		return err
+	}
 	protocol.TuneTCP(conn)
 	protocol.TuneTCPBuffer(conn, l.tcpBuffer)
 	l.conn = conn
@@ -285,12 +312,12 @@ func (l *txnLane) Do(payload []byte) ([]byte, error) {
 	_ = l.conn.SetDeadline(time.Now().Add(timeout))
 	requestID := requestCounter.Add(1)
 
-	if err := protocol.WriteRequestFrame(l.conn, requestID, payload); err != nil {
+	if err := protocol.WriteRequestFrameProfile(l.conn, requestID, payload, l.headerMask); err != nil {
 		l.closeLocked()
 		return nil, err
 	}
 
-	responseID, response, err := protocol.ReadResponseFrame(l.conn)
+	responseID, response, err := protocol.ReadResponseFrameProfile(l.conn, l.headerMask)
 	if err != nil {
 		l.closeLocked()
 		return nil, err
@@ -324,6 +351,28 @@ func doControl(lane *txnLane, payload []byte) ([]byte, error) {
 	return nil, lastErr
 }
 
+// ProbeProfile performs one small authenticated transaction using the selected
+// frame-magic mask. It does not create a target session.
+func ProbeProfile(serverAddr, token string, opts Options) bool {
+	timeout := opts.txnTimeout
+	if timeout <= 0 || timeout > 2*time.Second {
+		timeout = 2 * time.Second
+	}
+	lane := newTxnLane(serverAddr, opts.tcpBuffer, 1, timeout, opts.headerMask, opts.coverProfile)
+	defer lane.Close()
+	resp, err := lane.Do([]byte("CPROBE " + wireToken(token)))
+	if err != nil {
+		return false
+	}
+	if string(resp) == "PROBEOK" {
+		return true
+	}
+	// Servers predating profile discovery do not know CPROBE, but receiving a
+	// correctly framed error still proves that the legacy mask-zero header
+	// survived. The subsequent end-to-end probe remains authoritative.
+	return opts.headerMask == 0 && strings.HasPrefix(string(resp), "ERR expected TUNNEL")
+}
+
 type chunkResult struct {
 	seq   uint64
 	data  []byte
@@ -425,7 +474,7 @@ func Open(serverAddr, token, targetHost string, targetPort int, opts Options) (n
 	c.upSizer = newAdaptiveSizer("upload", opts)
 	c.downSizer = newAdaptiveSizer("download", opts)
 
-	c.pushLane = newTxnLane(serverAddr, opts.tcpBuffer, opts.reconnectEvery, opts.txnTimeout)
+	c.pushLane = newTxnLane(serverAddr, opts.tcpBuffer, opts.reconnectEvery, opts.txnTimeout, opts.headerMask, opts.coverProfile)
 
 	openPayload := []byte(fmt.Sprintf(
 		"COPEN %s %s %s %d",
@@ -464,7 +513,7 @@ func Open(serverAddr, token, targetHost string, targetPort int, opts Options) (n
 
 	c.pullLanes = make([]*txnLane, opts.pollers)
 	for i := 0; i < opts.pollers; i++ {
-		lane := newTxnLane(serverAddr, opts.tcpBuffer, opts.reconnectEvery, opts.txnTimeout)
+		lane := newTxnLane(serverAddr, opts.tcpBuffer, opts.reconnectEvery, opts.txnTimeout, opts.headerMask, opts.coverProfile)
 		c.pullLanes[i] = lane
 		c.workers.Add(1)
 		go c.pullWorker(lane)
@@ -762,7 +811,7 @@ func (c *chunkConn) Close() error {
 	c.once.Do(func() {
 		c.cancel()
 
-		lane := newTxnLane(c.serverAddr, c.opts.tcpBuffer, 1, c.opts.txnTimeout)
+		lane := newTxnLane(c.serverAddr, c.opts.tcpBuffer, 1, c.opts.txnTimeout, c.opts.headerMask, c.opts.coverProfile)
 		_, _ = doControl(lane, []byte(fmt.Sprintf("CCLOSE %s %s", wireToken(c.token), c.sid)))
 		lane.Close()