Index xroutes by (dest, nexthop) instead of just nexthop.

This avoids inconsistent routing if a neighbour is ingress filtering a
route.

babel.c

@@ -655,10 +655,11 @@ dump_tables(FILE *out)
                route_feasible(&routes[i]) ? " (feasible)" : "");
     }
     for(i = 0; i < numxroutes; i++) {
-        fprintf(out, "%s/%d gw %s cost %d metric %d age %d%s\n",
+        fprintf(out, "%s/%d gw %s nexthop %s cost %d metric %d age %d%s\n",
                 format_address(xroutes[i].prefix),
                 xroutes[i].plen,
                 format_address(xroutes[i].gateway->address),
+                format_address(xroutes[i].nexthop->address),
                 xroutes[i].cost,
                 xroutes[i].metric,
                 (int)(now.tv_sec - xroutes[i].time),

message.c

@@ -514,11 +514,14 @@ flushupdates(void)
                     int numpxroutes;
                     numpxroutes = 0;
                     for(j = 0; j < numxroutes; j++) {
-                        if(xroutes[j].gateway == buffered_updates[i])
+                        if(xroutes[j].installed &&
+                           xroutes[j].gateway == buffered_updates[i])
                             numpxroutes++;
                     }
                     start_message(net, 20 + 20 * numpxroutes);
                     for(j = 0; j < numxroutes; j++) {
+                        if(!xroutes[i].installed)
+                            continue;
                         if(xroutes[j].gateway != buffered_updates[i])
                             continue;
                         /* See comment above */

neighbour.c

@@ -31,6 +31,7 @@ THE SOFTWARE.
 #include "neighbour.h"
 #include "destination.h"
 #include "route.h"
+#include "xroute.h"
 #include "message.h"
 
 struct neighbour neighs[MAXNEIGHBOURS];
@@ -39,6 +40,7 @@ int numneighs = 0;
 void
 flush_neighbour(struct neighbour *neigh)
 {
+    flush_neighbour_xroutes(neigh);
     flush_neighbour_routes(neigh);
     memset(neigh, 0, sizeof(*neigh));
     if(neigh == &neighs[numneighs - 1]) {

route.c

@@ -159,6 +159,7 @@ install_route(struct route *route)
 
     for(i = 0; i < numxroutes; i++) {
         if(xroutes[i].gateway == route->dest &&
+           xroutes[i].nexthop == route->nexthop &&
            xroutes[i].time >= now.tv_sec - 240) {
             update_xroute_metric(&xroutes[i], xroutes[i].cost);
             consider_xroute(&xroutes[i]);
@@ -174,7 +175,7 @@ uninstall_route(struct route *route)
         return;
 
     for(i = 0; i < numxroutes; i++) {
-        if(xroutes[i].installed && xroutes[i].gateway == route->dest)
+        if(xroutes[i].installed && xroutes[i].nexthop == route->nexthop)
             uninstall_xroute(&xroutes[i]);
     }
 
@@ -329,11 +330,11 @@ update_route(const unsigned char *d, int seqno, int refmetric,
         change_route_metric(route, metric);
         if(seqno_compare(oldseqno, seqno) <= 0) {
             if(seqno_compare(oldseqno, seqno) < 0)
-                retract_xroutes(dest, pxroutes, numpxroutes);
+                retract_xroutes(dest, nexthop, pxroutes, numpxroutes);
             for(i = 0; i < numpxroutes; i++)
                 update_xroute(pxroutes[i].prefix,
                               pxroutes[i].plen,
-                              dest,
+                              dest, nexthop,
                               pxroutes[i].cost);
         }
         if(route->installed)
@@ -361,7 +362,7 @@ update_route(const unsigned char *d, int seqno, int refmetric,
         for(i = 0; i < numpxroutes; i++)
             update_xroute(pxroutes[i].prefix,
                           pxroutes[i].plen,
-                          dest,
+                          dest, nexthop,
                           pxroutes[i].cost);
         consider_route(route);
     }

xroute.c

@@ -74,6 +74,7 @@ static struct xroute *
 find_best_xroute(unsigned char *prefix, unsigned short plen)
 {
     struct xroute *xroute = NULL;
+    struct route *route;
     int i;
 
     for(i = 0; i < numxroutes; i++) {
@@ -82,8 +83,10 @@ find_best_xroute(unsigned char *prefix, unsigned short plen)
         if(xroutes[i].plen != plen ||
            memcmp(xroutes[i].prefix, prefix, 16) != 0)
             continue;
-        if((!xroute || xroutes[i].metric < xroute->metric) &&
-           find_installed_route(xroutes[i].gateway) != NULL)
+        route = find_installed_route(xroutes[i].gateway);
+        if(route->nexthop != xroutes[i].nexthop)
+            continue;
+        if(!xroute || xroutes[i].metric < xroute->metric)
             xroute = &xroutes[i];
     }
     return xroute;
@@ -109,7 +112,7 @@ install_xroute(struct xroute *xroute)
     }
 
     gwroute = find_installed_route(xroute->gateway);
-    if(!gwroute) {
+    if(!gwroute || gwroute->nexthop != xroute->nexthop) {
         fprintf(stderr,
                 "Attempted to install a blackhole xroute "
                 "(this shouldn't happen).\n");
@@ -162,11 +165,14 @@ void
 consider_xroute(struct xroute *xroute)
 {
     struct xroute *installed;
+    struct route *route;
 
     if(xroute->installed)
         return;
 
-    if(find_installed_route(xroute->gateway) == NULL)
+    route = find_installed_route(xroute->gateway);
+
+    if(xroute->nexthop != route->nexthop)
         return;
 
     installed = find_installed_myxroute(xroute->prefix, xroute->plen);
@@ -177,6 +183,17 @@ consider_xroute(struct xroute *xroute)
     }
 }
 
+void
+consider_all_xroutes(struct route *route)
+{
+    int i;
+
+    for(i = 0; i < numxroutes; i++) {
+        if(xroutes[i].nexthop == route->nexthop)
+            consider_route(route);
+    }
+}
+
 void
 flush_xroute(struct xroute *xroute)
 {
@@ -210,13 +227,29 @@ flush_xroute(struct xroute *xroute)
 }
 
 void
-retract_xroutes(struct destination *gateway,
+flush_neighbour_xroutes(struct neighbour *neigh)
+{
+    int i;
+
+    i = 0;
+    while(i < numxroutes) {
+        if(xroutes[i].nexthop == neigh) {
+            flush_xroute(xroutes + i);
+            continue;
+        }
+        i++;
+    }
+}
+
+void
+retract_xroutes(struct destination *gateway, struct neighbour *nexthop,
                 const struct xroute *except, int numexcept)
 {
     int i, j;
 
     for(i = 0; i < numxroutes; i++) {
-        if(xroutes[i].cost < INFINITY && xroutes[i].gateway == gateway) {
+        if(xroutes[i].cost < INFINITY && xroutes[i].gateway == gateway &&
+           xroutes[i].nexthop == nexthop) {
             for(j = 0; j < numexcept; j++) {
                 if(memcmp(xroutes[i].prefix, except[j].prefix, 16) == 0 &&
                    xroutes[i].plen == except[j].plen)
@@ -230,7 +263,7 @@ retract_xroutes(struct destination *gateway,
 
 struct xroute *
 update_xroute(const unsigned char *prefix, unsigned short plen,
-              struct destination *gateway, int cost)
+              struct destination *gateway, struct neighbour *nexthop, int cost)
 {
     int i;
     struct xroute *xroute = NULL;
@@ -248,7 +281,7 @@ update_xroute(const unsigned char *prefix, unsigned short plen,
 
     for(i = 0; i < numxroutes; i++) {
         xroute = &xroutes[i];
-        if(xroute->gateway == gateway &&
+        if(xroute->gateway == gateway && xroute->nexthop == nexthop &&
            memcmp(xroute->prefix, prefix, 16) == 0 && xroute->plen == plen) {
             update_xroute_metric(xroute, cost);
             xroute->time = now.tv_sec;
@@ -267,6 +300,7 @@ update_xroute(const unsigned char *prefix, unsigned short plen,
     memcpy(&xroute->prefix, prefix, 16);
     xroute->plen = plen;
     xroute->gateway = gateway;
+    xroute->nexthop = nexthop;
     xroute->cost = cost;
     xroute->metric =
         gwroute ? MIN(gwroute->metric + cost, INFINITY) : INFINITY;

xroute.h

@@ -26,6 +26,7 @@ struct xroute {
     unsigned char prefix[16];
     unsigned short plen;
     struct destination *gateway;
+    struct neighbour *nexthop;
     int cost;
     int metric;
     int time;
@@ -45,9 +46,11 @@ void install_xroute(struct xroute *xroute);
 void uninstall_xroute(struct xroute *xroute);
 void consider_xroute(struct xroute *xroute);
 void flush_xroute(struct xroute *xroute);
-void retract_xroutes(struct destination *gateway,
+void flush_neighbour_xroutes(struct neighbour *neigh);
+void retract_xroutes(struct destination *gateway, struct neighbour *nexthop,
                      const struct xroute *except, int numexcept);
 struct xroute * update_xroute(const unsigned char *prefix, unsigned short plen,
-                              struct destination *gateway, int cost);
+                              struct destination *gateway,
+                              struct neighbour *nexthop, int cost);
 void update_xroute_metric(struct xroute *xroute, int cost);
 int check_myxroutes(void);