Set the source prefixes through filters.

Since it's a route attribute, it fits better there.

babeld.man

@@ -472,6 +472,10 @@ For an input or output filter, allow this route after increasing its metric by
 .IR value .
 For a redistribute filter, redistribute this route with metric
 .IR value .
+.TP
+.BI src-prefix " prefix"
+For a redistribute filter, set the source prefix of this route to
+.IR prefix .
 .PP
 If
 .I action
@@ -514,6 +518,12 @@ or, if you want to constrain the routes that you redistribute,
     \-C 'redistribute proto 11 ip ::/0 le 64 metric 256' \\
     \-C 'redistribute proto 11 ip 0.0.0.0/0 le 24 metric 256' \\
     wlan0
+.SS Source-sensitive routing
+.PP
+If your want to redistribute kernel routes as source-specific to the network,
+with the 2001:DB8:0:1::/64 prefix:
+.IP
+redistribute src-prefix 2001:DB8:0:1::/64
 .SH FILES
 .TP
 .B /etc/babeld.conf

configuration.c

@@ -381,16 +381,28 @@ parse_filter(int c, gnc_t gnc, void *closure, struct filter **filter_return)
             filter->ifname = interface;
             filter->ifindex = if_nametoindex(interface);
         } else if(strcmp(token, "allow") == 0) {
-            filter->add_metric = 0;
+            filter->action.add_metric = 0;
         } else if(strcmp(token, "deny") == 0) {
-            filter->add_metric = INFINITY;
+            filter->action.add_metric = INFINITY;
         } else if(strcmp(token, "metric") == 0) {
             int metric;
             c = getint(c, &metric, gnc, closure);
             if(c < -1) goto error;
             if(metric <= 0 || metric > INFINITY)
                 goto error;
-            filter->add_metric = metric;
+            filter->action.add_metric = metric;
+        } else if(strcmp(token, "src-prefix") == 0) {
+            int af;
+            c = getnet(c, &filter->action.src_prefix, &filter->action.src_plen,
+                       &af, gnc, closure);
+            if(c < -1)
+                goto error;
+            if(filter->af == AF_UNSPEC)
+                filter->af = af;
+            else if(filter->af != af)
+                goto error;
+            if(af == AF_INET && filter->action.src_plen == 96)
+                memset(&filter->action.src_prefix, 0, 16);
         } else {
             goto error;
         }
@@ -988,12 +1000,18 @@ static int
 do_filter(struct filter *f, const unsigned char *id,
           const unsigned char *prefix, unsigned short plen,
           const unsigned char *src_prefix, unsigned short src_plen,
-          const unsigned char *neigh, unsigned int ifindex, int proto)
+          const unsigned char *neigh, unsigned int ifindex, int proto,
+          struct filter_result *result)
 {
+    if(result)
+        memset(result, 0, sizeof(struct filter_result));
     while(f) {
         if(filter_match(f, id, prefix, plen, src_prefix, src_plen,
-                        neigh, ifindex, proto))
-            return f->add_metric;
+                        neigh, ifindex, proto)) {
+            if(result)
+                memcpy(result, &f->action, sizeof(struct filter_result));
+            return f->action.add_metric;
+        }
         f = f->next;
     }
     return -1;
@@ -1003,11 +1021,12 @@ int
 input_filter(const unsigned char *id,
              const unsigned char *prefix, unsigned short plen,
              const unsigned char *src_prefix, unsigned short src_plen,
-             const unsigned char *neigh, unsigned int ifindex)
+             const unsigned char *neigh, unsigned int ifindex,
+             struct filter_result *result)
 {
     int res;
     res = do_filter(input_filters, id, prefix, plen,
-                    src_prefix, src_plen, neigh, ifindex, 0);
+                    src_prefix, src_plen, neigh, ifindex, 0, result);
     if(res < 0)
         res = 0;
     return res;
@@ -1017,11 +1036,12 @@ int
 output_filter(const unsigned char *id,
               const unsigned char *prefix, unsigned short plen,
               const unsigned char *src_prefix, unsigned short src_plen,
-              unsigned int ifindex)
+              unsigned int ifindex,
+              struct filter_result *result)
 {
     int res;
     res = do_filter(output_filters, id, prefix, plen,
-                    src_prefix, src_plen, NULL, ifindex, 0);
+                    src_prefix, src_plen, NULL, ifindex, 0, result);
     if(res < 0)
         res = 0;
     return res;
@@ -1030,11 +1050,12 @@ output_filter(const unsigned char *id,
 int
 redistribute_filter(const unsigned char *prefix, unsigned short plen,
                     const unsigned char *src_prefix, unsigned short src_plen,
-                    unsigned int ifindex, int proto)
+                    unsigned int ifindex, int proto,
+                    struct filter_result *result)
 {
     int res;
     res = do_filter(redistribute_filters, NULL, prefix, plen,
-                    src_prefix, src_plen, NULL, ifindex, proto);
+                    src_prefix, src_plen, NULL, ifindex, proto, result);
     if(res < 0)
         res = INFINITY;
     return res;

configuration.h

@@ -20,6 +20,12 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 */
 
+struct filter_result {
+    unsigned int add_metric; /* allow = 0, deny = INF, metric = <0..INF> */
+    unsigned char *src_prefix;
+    unsigned char src_plen;
+};
+
 struct filter {
     int af;
     char *ifname;
@@ -33,7 +39,7 @@ struct filter {
     unsigned char src_plen_ge, src_plen_le;
     unsigned char *neigh;
     int proto;                  /* May be negative */
-    unsigned int add_metric;
+    struct filter_result action;
     struct filter *next;
 };
 
@@ -46,12 +52,15 @@ void renumber_filters(void);
 int input_filter(const unsigned char *id,
                  const unsigned char *prefix, unsigned short plen,
                  const unsigned char *src_prefix, unsigned short src_plen,
-                 const unsigned char *neigh, unsigned int ifindex);
+                 const unsigned char *neigh, unsigned int ifindex,
+                 struct filter_result *result);
 int output_filter(const unsigned char *id,
                   const unsigned char *prefix, unsigned short plen,
                   const unsigned char *src_prefix, unsigned short src_plen,
-                  unsigned int ifindex);
+                  unsigned int ifindex,
+                  struct filter_result *result);
 int redistribute_filter(const unsigned char *prefix, unsigned short plen,
                     const unsigned char *src_prefix, unsigned short src_plen,
-                    unsigned int ifindex, int proto);
+                    unsigned int ifindex, int proto,
+                    struct filter_result *result);
 int finalise_config(void);

message.c

@@ -1093,7 +1093,7 @@ really_send_update(struct interface *ifp,
         return;
 
     add_metric = output_filter(id, prefix, plen, src_prefix,
-                               src_plen, ifp->ifindex);
+                               src_plen, ifp->ifindex, NULL);
     if(add_metric >= INFINITY)
         return;
 

resend.c

@@ -101,10 +101,11 @@ record_resend(int kind, const unsigned char *prefix, unsigned char plen,
         return 0;
 
     if((kind == RESEND_REQUEST &&
-        input_filter(NULL, prefix, plen, NULL, 0, NULL, ifindex) >=
+        input_filter(NULL, prefix, plen, NULL, 0, NULL, ifindex, NULL) >=
         INFINITY) ||
        (kind == RESEND_UPDATE &&
-        output_filter(NULL, prefix, plen, src_prefix, src_plen, ifindex) >=
+        output_filter(NULL, prefix, plen, src_prefix, src_plen,
+                      ifindex, NULL) >=
         INFINITY))
         return 0;
 

route.c

@@ -767,7 +767,7 @@ update_route_metric(struct babel_route *route)
                                       route->src->src_prefix,
                                       route->src->src_plen,
                                       neigh->address,
-                                      neigh->ifp->ifindex);
+                                      neigh->ifp->ifindex, NULL);
         change_route_metric(route, route->refmetric,
                             neighbour_cost(route->neigh), add_metric);
         if(route_metric(route) != oldmetric ||
@@ -849,9 +849,9 @@ update_route(const unsigned char *id,
         return NULL;
 
 
-    add_metric = input_filter(id, prefix, plen,
-                              src_prefix, src_plen,
-                              neigh->address, neigh->ifp->ifindex);
+    add_metric = input_filter(id, prefix, plen, src_prefix, src_plen,
+                              neigh->address, neigh->ifp->ifindex,
+                              NULL);
     if(add_metric >= INFINITY)
         return NULL;
 

xroute.c

@@ -169,7 +169,8 @@ check_xroutes(int send_updates)
 {
     int i, j, metric, export, change = 0, rc;
     struct kernel_route *routes;
-    int numroutes;
+    struct filter_result filter_result = {0};
+    int numroutes, numaddresses;
     static int maxroutes = 8;
     const int maxmaxroutes = 16 * 1024;
 
@@ -191,6 +192,8 @@ check_xroutes(int send_updates)
     if(numroutes >= maxroutes)
         goto resize;
 
+    numaddresses = numroutes;
+
     rc = kernel_routes(routes + numroutes, maxroutes - numroutes);
     if(rc < 0)
         fprintf(stderr, "Couldn't get kernel routes.\n");
@@ -200,6 +203,21 @@ check_xroutes(int send_updates)
     if(numroutes >= maxroutes)
         goto resize;
 
+    /* Apply filter to kernel routes (e.g. change the source prefix). */
+
+    for(i = numaddresses; i < numroutes; i++) {
+        filter_result.src_prefix = NULL;
+        redistribute_filter(routes[i].prefix, routes[i].plen,
+                            routes[i].src_prefix, routes[i].src_plen,
+                            routes[i].ifindex, routes[i].proto,
+                            &filter_result);
+        if(filter_result.src_prefix) {
+            memcpy(routes[i].src_prefix, filter_result.src_prefix, 16);
+            routes[i].src_plen = filter_result.src_plen;
+        }
+
+    }
+
     /* Check for any routes that need to be flushed */
 
     i = 0;
@@ -207,7 +225,8 @@ check_xroutes(int send_updates)
         export = 0;
         metric = redistribute_filter(xroutes[i].prefix, xroutes[i].plen,
                                      xroutes[i].src_prefix, xroutes[i].src_plen,
-                                     xroutes[i].ifindex, xroutes[i].proto);
+                                     xroutes[i].ifindex, xroutes[i].proto,
+                                     NULL);
         if(metric < INFINITY && metric == xroutes[i].metric) {
             for(j = 0; j < numroutes; j++) {
                 if(xroutes[i].plen == routes[j].plen &&
@@ -249,7 +268,7 @@ check_xroutes(int send_updates)
             continue;
         metric = redistribute_filter(routes[i].prefix, routes[i].plen,
                                      routes[i].src_prefix, routes[i].src_plen,
-                                     routes[i].ifindex, routes[i].proto);
+                                     routes[i].ifindex, routes[i].proto, NULL);
         if(metric < INFINITY) {
             rc = add_xroute(routes[i].prefix, routes[i].plen,
                             routes[i].src_prefix, routes[i].src_plen,