Implements token bucket filter for rate limiting.

lib/tbf.c

@@ -0,0 +1,29 @@
+/*
+ *	BIRD Library -- Token Bucket Filter
+ *
+ *	(c) 2014 Ondrej Zajicek <santiago@crfreenet.org>
+ *	(c) 2014 CZ.NIC z.s.p.o.
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include "nest/bird.h"
+
+void
+tbf_update(struct tbf *f)
+{
+  bird_clock_t delta = now - f->timestamp;
+
+  if (delta == 0)
+    return;
+
+  f->timestamp = now;
+
+  if ((0 < delta) && (delta < f->burst))
+  {
+    u32 next = f->count + delta * f->rate;
+    f->count = MIN(next, f->burst);
+  }
+  else
+    f->count = f->burst;
+}