netsniff-ng: Add netlink dissector

Add an initial implementation of a dissector to work on netlink messages
as received from an nlmon device.

Use can use it as follows to monitor netlink traffic to/from the kernel:

  modprobe nlmon
  ip link add type nlmon
  ip link set nlmon0 up

  netsniff-ng -i nlmon0

  ip link set nlmon 0 down
  ip link del dev nlmon0
  rmmod nlmon

Fixes: #89
Suggested-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 33 insertions, 0 deletions

diff --git a/dissector_netlink.c b/dissector_netlink.c
new file mode 100644
index 0000000..387f198
--- /dev/null
+++ b/dissector_netlink.c
@@ -0,0 +1,33 @@
+/*
+ * netsniff-ng - the packet sniffing beast
+ * Copyright 2014 Tobias Klauser.
+ * Subject to the GPL, version 2.
+ */
+
+#include "dissector.h"
+#include "dissector_netlink.h"
+
+#ifdef HAVE_DISSECTOR_PROTOS
+static inline void dissector_init_entry(int type)
+{
+	dissector_set_print_type(&nlmsg_ops, type);
+}
+
+static inline void dissector_init_exit(int type)
+{
+	dissector_set_print_type(&none_ops, type);
+}
+#else
+static inline void dissector_init_entry(int type __maybe_unused) {}
+static inline void dissector_init_exit(int type __maybe_unused) {}
+#endif
+
+void dissector_init_netlink(int fnttype)
+{
+	dissector_init_entry(fnttype);
+	dissector_init_exit(fnttype);
+}
+
+void dissector_cleanup_netlink(void)
+{
+}