+/* Primitive operations. */
+@native protected def open_tun(): Int;
+@native protected def base_init();
+@native protected def setup_resolver();
+@native def load_keys(priv: CString, pub: CString, tag: CString);
+@native def unload_keys();
+@native def bind(host: CString, svc: CString);
+@native def unbind();
+@native def mark(seq: Int);
+@native def run();
+@native protected def send(buf: CString, start: Int, len: Int,
+ trig: Wrapper);
+@native protected def recv(buf: CString, start: Int, len: Int,
+ trig: Wrapper): Int;
+
+base_init();
+setup_resolver();
+
+/* Tunnel descriptor plumbing. */
+val pending = HashMap[String, Int]();
+
+def getTunnelFd(peer: CString): Int =
+ pending synchronized { pending(peer.toJString) };
+def storeTunnelFd(peer: String, fd: Int)
+ { pending synchronized { pending(peer) = fd; } }
+def withdrawTunnelFd(peer: String)
+ { pending synchronized { pending -= peer; } }
+def withTunnelFd[T](peer: String, fd: Int)(body: => T): T = {
+ storeTunnelFd(peer, fd);
+ try { body } finally { withdrawTunnelFd(peer); }
+}