Improve tls writer

common/badtls/link.go

@@ -0,0 +1,26 @@
+//go:build go1.19 && !go.1.20
+
+package badtls
+
+import (
+	"crypto/tls"
+	"reflect"
+	_ "unsafe"
+)
+
+const (
+	maxPlaintext    = 16384 // maximum plaintext payload length
+	recordHeaderLen = 5     // record header length
+)
+
+//go:linkname errShutdown crypto/tls.errShutdown
+var errShutdown error
+
+//go:linkname handshakeComplete crypto/tls.(*Conn).handshakeComplete
+func handshakeComplete(conn *tls.Conn) bool
+
+//go:linkname incSeq crypto/tls.(*halfConn).incSeq
+func incSeq(conn uintptr)
+
+//go:linkname valueInterface reflect.valueInterface
+func valueInterface(v reflect.Value, safe bool) any