Add API function to research some routes, or approximations.

route.c

@@ -389,6 +389,107 @@ route_stream_done(struct route_stream *stream)
     free(stream);
 }
 
+/* Search for a route having dst_prefix/dst_len as destination prefix and
+   src_prefix/src_plen as source prefix.  However, if is_min_dst is specified,
+   the route returns has just as constraint to contains the given destination
+   prefix.  As multiple routes can matched this one, the minimum among the
+   possibles routes is returned.  If exclusive_min is specified, it will be
+   requier for the destination to be different than the one in argument.  The
+   same behaviour holds for the source prefix with is_min_src. */
+struct babel_route *
+find_min_iroute(const unsigned char *dst_prefix, unsigned char dst_plen,
+                const unsigned char *src_prefix, unsigned char src_plen,
+                int is_min_dst, int is_min_src, int exclusive_min)
+{
+    enum prefix_status st;
+    struct babel_route *result = NULL;
+    int i;
+
+    if(!is_min_dst && !is_min_src) {
+        i = find_route_slot(dst_prefix, dst_plen, src_prefix, src_plen, NULL);
+        result = (i < 0 || !routes[i]->installed) ? NULL : routes[i];
+
+    } else if(is_min_src) { /* only dst is exactly specified */
+        for(i = 0; i < route_slots; i++) {
+            if(!routes[i]->installed)
+                continue;
+            st = prefix_cmp(dst_prefix, dst_plen,
+                            routes[i]->src->prefix, routes[i]->src->plen);
+            if(st != PST_EQUALS)
+                continue;
+            st = prefix_cmp(src_prefix, src_plen,
+                            routes[i]->src->src_prefix,
+                            routes[i]->src->src_plen);
+            if(!(st & (exclusive_min ? PST_MORE_SPECIFIC :
+                       PST_MORE_SPECIFIC | PST_EQUALS)))
+                continue;
+            if(result &&
+               (prefix_cmp(result->src->src_prefix,
+                           result->src->src_plen,
+                           routes[i]->src->src_prefix,
+                           routes[i]->src->src_plen)
+                == PST_MORE_SPECIFIC))
+                continue;
+
+            result = routes[i];
+        }
+
+    } else if(is_min_dst) { /* only src is exactly specified */
+        for(i = 0; i < route_slots; i++) {
+            if(!routes[i]->installed)
+                continue;
+            st = prefix_cmp(src_prefix, src_plen,
+                            routes[i]->src->src_prefix,
+                            routes[i]->src->src_plen);
+            if(st != PST_EQUALS)
+                continue;
+            st = prefix_cmp(dst_prefix, dst_plen,
+                            routes[i]->src->prefix, routes[i]->src->plen);
+            if(!(st & (exclusive_min ? PST_MORE_SPECIFIC :
+                       PST_MORE_SPECIFIC | PST_EQUALS)))
+                continue;
+            if(result &&
+               (prefix_cmp(result->src->prefix,
+                           result->src->plen,
+                           routes[i]->src->prefix,
+                           routes[i]->src->plen)
+                == PST_MORE_SPECIFIC))
+                continue;
+
+            result = routes[i];
+        }
+
+    } else {
+        for(i = 0; i < route_slots; i++) {
+            if(!routes[i]->installed)
+                continue;
+            st = prefix_cmp(dst_prefix, dst_plen,
+                            routes[i]->src->prefix, routes[i]->src->plen);
+            if(!(st & (exclusive_min ? PST_MORE_SPECIFIC :
+                       PST_MORE_SPECIFIC | PST_EQUALS)))
+                continue;
+            st = prefix_cmp(src_prefix, src_plen,
+                            routes[i]->src->src_prefix,
+                            routes[i]->src->src_plen);
+            if(!(st & (exclusive_min ? PST_MORE_SPECIFIC :
+                       PST_MORE_SPECIFIC | PST_EQUALS)))
+                continue;
+            if(result &&
+               (prefix_cmp(result->src->src_prefix,
+                           result->src->src_plen,
+                           routes[i]->src->src_prefix,
+                           routes[i]->src->src_plen)
+                == PST_MORE_SPECIFIC))
+                continue;
+
+            result = routes[i];
+        }
+    }
+    if(result)
+        assert(v4mapped(dst_prefix) == v4mapped(result->src->prefix));
+    return result;
+}
+
 static int
 metric_to_kernel(int metric)
 {