Make deny & src-prefix actions work in install filter

babeld.man

@@ -578,8 +578,26 @@ For a redistribute filter, redistribute this route with metric
 .IR value .
 .TP
 .BI src-prefix " prefix"
+.RS
+On Linux, this action is about the
+.BR from
+option in
+.BR ip-route (8).
 For a redistribute filter, set the source prefix of this route to
 .IR prefix .
+For an install filter:
+.IP \(bu 2
+when
+.IR prefix
+matches exactly the source prefix of the route to install,
+the latter is cleared at install;
+.IP \(bu
+otherwise, the route is not installed.
+.P
+The purpose of such an install filter is mainly to provide a fallback for
+routers without support of source-specific routes: only one route is kept,
+to a router that will be able to route correctly.
+.RE
 .TP
 .BI table " table"
 In an

configuration.c

@@ -1511,12 +1511,8 @@ install_filter(const unsigned char *prefix, unsigned short plen,
                unsigned int ifindex,
                struct filter_result *result)
 {
-    int res;
-    res = do_filter(install_filters, NULL, prefix, plen,
+    return do_filter(install_filters, NULL, prefix, plen,
                      src_prefix, src_plen, NULL, ifindex, 0, result);
-    if(res < 0)
-        res = INFINITY;
-    return res;
 }
 
 int

disambiguation.c

@@ -215,7 +215,7 @@ is_installed(struct zone *zone)
 }
 
 static int
-change_route(int operation, const struct zone *zone,
+change_route(int operation, struct zone *zone,
              const struct babel_route *route, int metric,
              const unsigned char *new_next_hop,
              int new_ifindex, int new_metric)
@@ -227,8 +227,19 @@ change_route(int operation, const struct zone *zone,
     int m = install_filter(zone->dst_prefix, zone->dst_plen,
                            zone->src_prefix, zone->src_plen,
                            ifindex, &filter_result);
-    if (m < INFINITY)
+    if(m >= 0) {
+        if(m == INFINITY)
+            return 0;
+        if(filter_result.src_prefix) {
+            if(prefix_cmp(zone->src_prefix, zone->src_plen,
+                          filter_result.src_prefix, filter_result.src_plen)
+                    != PST_EQUALS)
+                return 0;
+            zone->src_plen = zone->src_plen >= 96 && v4mapped(zone->src_prefix)
+                ? 96 : 0;
+        }
         pref_src = filter_result.pref_src;
+    }
 
     int table = filter_result.table ? filter_result.table :
         find_table(zone->dst_prefix, zone->dst_plen,
@@ -242,21 +253,21 @@ change_route(int operation, const struct zone *zone,
 }
 
 static int
-add_route(const struct zone *zone, const struct babel_route *route)
+add_route(struct zone *zone, const struct babel_route *route)
 {
     return change_route(ROUTE_ADD, zone, route,
                         metric_to_kernel(route_metric(route)), NULL, 0, 0);
 }
 
 static int
-del_route(const struct zone *zone, const struct babel_route *route)
+del_route(struct zone *zone, const struct babel_route *route)
 {
     return change_route(ROUTE_FLUSH, zone, route,
                         metric_to_kernel(route_metric(route)), NULL, 0, 0);
 }
 
 static int
-chg_route(const struct zone *zone, const struct babel_route *old,
+chg_route(struct zone *zone, const struct babel_route *old,
           const struct babel_route *new)
 {
     return change_route(ROUTE_MODIFY, zone, old,
@@ -266,7 +277,7 @@ chg_route(const struct zone *zone, const struct babel_route *old,
 }
 
 static int
-chg_route_metric(const struct zone *zone, const struct babel_route *route,
+chg_route_metric(struct zone *zone, const struct babel_route *route,
                  int old_metric, int new_metric)
 {
     return change_route(ROUTE_MODIFY, zone, route,