+/* --- @p_addtun@ --- *
+ *
+ * Arguments: @const tunnel_ops *tops@ = tunnel ops to add
+ *
+ * Returns: Zero on success, @-1@ on failure.
+ *
+ * Use: Adds a tunnel class to the list of known classes, if it
+ * initializes properly. If there is no current default tunnel,
+ * then this one is made the default.
+ *
+ * Does nothing if the tunnel class is already known. So adding
+ * a bunch of tunnels takes quadratic time, but there will be
+ * too few to care about.
+ */
+
+extern int p_addtun(const tunnel_ops */*tops*/);
+
+/* --- @p_setdflttun@ --- *
+ *
+ * Arguments: @const tunnel_ops *tops@ = tunnel ops to set
+ *
+ * Returns: ---
+ *
+ * Use: Sets the default tunnel. It must already be registered. The
+ * old default is forgotten.
+ */
+
+extern void p_setdflttun(const tunnel_ops */*tops*/);
+
+/* --- @p_dflttun@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: A pointer to the current default tunnel operations, or null
+ * if no tunnels are defined.
+ */
+
+extern const tunnel_ops *p_dflttun(void);
+
+/* --- @p_findtun@ --- *
+ *
+ * Arguments: @const char *name@ = tunnel name
+ *
+ * Returns: Pointer to the tunnel operations, or null.
+ *
+ * Use: Finds the operations for a named tunnel class.
+ */
+
+extern const tunnel_ops *p_findtun(const char */*name*/);
+
+/* --- @p_mktuniter@ --- *
+ *
+ * Arguments: @tuniter *i@ = pointer to iterator to initialize
+ *
+ * Returns: ---
+ *
+ * Use: Initializes a tunnel iterator.
+ */
+
+extern void p_mktuniter(tun_iter */*i*/);
+
+/* --- @p_nexttun@ --- *
+ *
+ * Arguments: @tuniter *i@ = pointer to iterator
+ *
+ * Returns: Pointer to the next tunnel's operations, or null.
+ */
+
+extern const tunnel_ops *p_nexttun(tun_iter */*i*/);
+
+/* --- @FOREACH_TUN@ --- *
+ *
+ * Arguments: @tops@ = name to bind to each tunnel
+ * @stuff@ = thing to do for each item
+ *
+ * Use: Does something for each known tunnel class.
+ */
+
+#define FOREACH_TUN(tops, stuff) do { \
+ tun_iter i_; \
+ const tunnel_ops *tops; \
+ for (p_mktuniter(&i_); (tops = p_nexttun(&i_)) != 0; ) stuff; \
+} while (0)
+