1 files changed, 83 insertions, 0 deletions
diff --git a/ffd/announce.c b/ffd/announce.c
new file mode 100644
index 0000000..eade2f1
--- /dev/null
+++ b/ffd/announce.c
@@ -0,0 +1,83 @@
+/*
+  Copyright (c) 2012, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+
+#include "ffd.h"
+
+
+static bool is_feasable(const ffd_announce_t *announce, const ffd_nexthop_t *nexthop) {
+	if (FFD_IS_INFINITY(announce->feasability_distance))
+		return true;
+
+	int16_t seqno_diff = nexthop->metric_seqno.seqno - announce->feasability_distance.seqno;
+
+	if (seqno_diff < 0)
+		return true;
+	if (seqno_diff == 0 && nexthop->metric_seqno.metric < announce->feasability_distance.metric)
+		return true;
+
+	return false;
+}
+
+static ffd_nexthop_t* select_nexthop(const ffd_announce_t *announce) {
+	ffd_nexthop_t *ret = NULL;
+
+	ffd_nexthop_t *nexthop;
+	for (nexthop = announce->nexthop_list->next; nexthop; nexthop = nexthop->next) {
+		if (is_feasable(announce, nexthop))
+			continue;
+
+		int16_t seqno_diff = nexthop->metric_seqno.seqno - ret->metric_seqno.seqno;
+
+		if (nexthop->metric_seqno.metric < ret->metric_seqno.metric
+		    || (nexthop->metric_seqno.metric == ret->metric_seqno.metric && seqno_diff < 0)) {
+			ret = nexthop;
+		}
+	}
+
+	return ret;
+}
+
+ffd_metric_seqno_t ffd_announce_get_metric(const ffd_announce_t *announce) {
+	ffd_nexthop_t *nexthop = select_nexthop(announce);
+
+	if (nexthop)
+		return nexthop->metric_seqno;
+	else
+		return (ffd_metric_seqno_t){0xffff, 0};
+}
+
+
+ffd_announce_t* ffd_announce_new(size_t len) {
+	ffd_announce_t *a = calloc(1, sizeof(ffd_announce_t)+len);
+
+	a->len = len;
+	a->feasability_distance = (ffd_metric_seqno_t){0xffff, 0};
+
+	a->next = announce_list;
+	announce_list = a;
+
+	return a;
+}