Add support for listening for interface arrival/departure events on

PF_SYSTEM sockets on OS X.

Pull iface_mon_nl_init() into iface_mon_start(), to make it a little
easier to figure out what interface monitoring code on other platforms
should do.

Add a bunch of XXX comments about additional things we should perhaps
do.

svn path=/trunk/; revision=43545

1 files changed, 33 insertions, 0 deletions

diff --git a/iface_monitor.h b/iface_monitor.h
index b883a7421f..a24c93ef4e 100644
--- a/iface_monitor.h
+++ b/iface_monitor.h
@@ -26,16 +26,49 @@
 
 #ifdef HAVE_LIBPCAP
 
+/*
+ * Callback for interface changes.
+ *
+ * iface is a pointer to the name of the interface.
+ *
+ * up is 1 if the interface is up, 0 if it's down.
+ *
+ * XXX - we really want "gone", not "down", where "gone" may include
+ * "down" if the OS requires an interface to be up in order to start
+ * a capture on it (as is the case in Linux and in OS X prior to
+ * Lion), but should also include *gone*, as in "there is no longer
+ * an interface with this name, so it's neither down nor up".
+ *
+ * We also may want other events, such as address changes, so what
+ * we might want is "add", "remove", and "modify" as the events.
+ */
 typedef void (*iface_mon_cb)(const char *iface, int up);
+
+/*
+ * Start watching for interface changes.
+ */
 int
 iface_mon_start(iface_mon_cb cb);
 
+/*
+ * Stop watching for interface changes.
+ */
 void
 iface_mon_stop(void);
 
+/*
+ * Get the socket on which interface changes are delivered, so that
+ * we can add it to the event loop.
+ *
+ * XXX - what if it's not a socket or other file descriptor?
+ */
 int
 iface_mon_get_sock(void);
 
+/*
+ * Call this if something is readable from the interface change socket.
+ * It will call the callback as appropriate.
+ */
 void
 iface_mon_event(void);