Fix bug in shortest path implementation

src/graph.c

@@ -141,6 +141,7 @@ void sssp_bfs(void) {
 	myself->prevedge = NULL;
 	myself->via = myself;
 	myself->distance = 0;
+	myself->weighted_distance = 0;
 	list_insert_head(todo_list, myself);
 
 	/* Loop while todo_list is filled */
@@ -178,14 +179,15 @@ void sssp_bfs(void) {
 
 			if(e->to->status.visited
 			                && (!e->to->status.indirect || indirect)
-			                && (e->to->distance != n->distance + 1 || e->weight >= e->to->prevedge->weight)) {
+			                && (e->to->distance != n->distance + 1 || e->to->weighted_distance <= n->weighted_distance + e->weight)) {
 				continue;
 			}
 
 			// Only update nexthop if it doesn't increase the path length
 
-			if(!e->to->status.visited || (e->to->distance == n->distance + 1 && e->weight < e->to->prevedge->weight)) {
+			if(!e->to->status.visited || (e->to->distance == n->distance + 1 && e->to->weighted_distance > n->weighted_distance + e->weight)) {
 				e->to->nexthop = (n->nexthop == myself) ? e->to : n->nexthop;
+				e->to->weighted_distance = n->weighted_distance + e->weight;
 			}
 
 			e->to->status.visited = true;

src/node.h

@@ -76,6 +76,7 @@ typedef struct node_t {
 	compression_level_t outcompression;     /* Compression level, 0 = no compression */
 
 	int distance;
+	int weighted_distance;
 	struct node_t *nexthop;                 /* nearest node from us to him */
 	struct edge_t *prevedge;                /* nearest node from him to us */
 	struct node_t *via;                     /* next hop for UDP packets */

test/unit/test_graph.c

@@ -26,6 +26,54 @@ static node_t *make_node(const char *name) {
 	return node;
 }
 
+static void test_sssp_bfs_2(void **state) {
+	(void)state;
+
+	node_t *mars = make_node("mars");
+	node_t *saturn = make_node("saturn");
+	node_t *neptune = make_node("neptune");
+
+	//          1000            500
+	// myself ---------- mars ------------- neptune
+	//      \                              /
+	//       ------- saturn --------------
+	//          50               501
+
+	// Upper route
+	connect_nodes(myself, mars, 1000);
+	connect_nodes(mars, neptune, 500);
+
+	// Lower route
+	connect_nodes(myself, saturn, 50);
+	connect_nodes(saturn, neptune, 501);
+
+	sssp_bfs();
+
+	assert_true(mars->status.visited);
+	assert_true(saturn->status.visited);
+	assert_true(neptune->status.visited);
+
+	assert_false(mars->status.indirect);
+	assert_false(saturn->status.indirect);
+	assert_false(neptune->status.indirect);
+
+	assert_int_equal(1, mars->distance);
+	assert_int_equal(1, saturn->distance);
+	assert_int_equal(2, neptune->distance);
+
+	assert_ptr_equal(mars, mars->nexthop);
+	assert_ptr_equal(saturn, saturn->nexthop);
+	assert_ptr_equal(saturn, neptune->nexthop);
+
+	assert_ptr_equal(lookup_edge(myself, mars), mars->prevedge);
+	assert_ptr_equal(lookup_edge(myself, saturn), saturn->prevedge);
+	assert_ptr_equal(lookup_edge(saturn, neptune), neptune->prevedge);
+
+	assert_ptr_equal(mars, mars->via);
+	assert_ptr_equal(saturn, saturn->via);
+	assert_ptr_equal(neptune, neptune->via);
+}
+
 static void test_sssp_bfs(void **state) {
 	(void)state;
 
@@ -91,6 +139,7 @@ static int teardown(void **state) {
 int main(void) {
 	const struct CMUnitTest tests[] = {
 		cmocka_unit_test_setup_teardown(test_sssp_bfs, setup, teardown),
+		cmocka_unit_test_setup_teardown(test_sssp_bfs_2, setup, teardown)
 	};
 	return cmocka_run_group_tests(tests, NULL, NULL);
 }