RTA_PREFSRC

babeld.c

@@ -106,6 +106,7 @@ main(int argc, char **argv)
     void *vrc;
     unsigned int seed;
     struct interface *ifp;
+    unsigned char *addr;
 
     gettime(&now);
 
@@ -123,7 +124,7 @@ main(int argc, char **argv)
     change_smoothing_half_life(4);
 
     while(1) {
-        opt = getopt(argc, argv, "m:p:h:H:i:k:A:sruS:d:g:lwz:M:t:T:c:C:DL:I:F");
+        opt = getopt(argc, argv, "m:p:h:H:i:k:A:sruS:d:g:lwz:M:t:T:c:C:DL:I:FP:");
         if(opt < 0)
             break;
 
@@ -256,6 +257,13 @@ main(int argc, char **argv)
         case 'F':
             setup = 1;
             break;
+        case 'P':
+            addr = malloc(16);
+            rc = parse_address(optarg, addr, &i);
+            if(rc < 0)
+                goto usage;
+            preferred_source[i == AF_INET] = addr;
+            break;
         default:
             goto usage;
         }

kernel.h

@@ -43,6 +43,7 @@ struct kernel_route {
 #define CHANGE_ADDR  (1 << 2)
 
 extern int export_table, import_table;
+extern unsigned char *preferred_source[2];
 
 int kernel_setup(int setup);
 int kernel_setup_socket(int setup);

kernel_netlink.c

@@ -52,6 +52,7 @@ THE SOFTWARE.
 #include "interface.h"
 
 int export_table = -1, import_table = -1;
+unsigned char *preferred_source[2] = {NULL, NULL};
 
 static int old_forwarding = -1;
 static int old_ipv4_forwarding = -1;
@@ -940,45 +941,45 @@ kernel_route(int operation, const unsigned char *dest, unsigned short plen,
 
     rta = RTM_RTA(rtm);
 
-    if(ipv4) {
-        rta = RTA_NEXT(rta, len);
-        rta->rta_len = RTA_LENGTH(sizeof(struct in_addr));
-        rta->rta_type = RTA_DST;
-        memcpy(RTA_DATA(rta), dest + 12, sizeof(struct in_addr));
-    } else {
-        rta = RTA_NEXT(rta, len);
-        rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
-        rta->rta_type = RTA_DST;
-        memcpy(RTA_DATA(rta), dest, sizeof(struct in6_addr));
-    }
+#define ADD_IPARG(type, addr) \
+    do if(ipv4) { \
+        rta = RTA_NEXT(rta, len); \
+        rta->rta_len = RTA_LENGTH(sizeof(struct in_addr)); \
+        rta->rta_type = type; \
+        memcpy(RTA_DATA(rta), addr + 12, sizeof(struct in_addr)); \
+    } else { \
+        rta = RTA_NEXT(rta, len); \
+        rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr)); \
+        rta->rta_type = type; \
+        memcpy(RTA_DATA(rta), addr, sizeof(struct in6_addr)); \
+    } while (0)
+
+    ADD_IPARG(RTA_DST, dest);
 
     rta = RTA_NEXT(rta, len);
     rta->rta_len = RTA_LENGTH(sizeof(int));
     rta->rta_type = RTA_PRIORITY;
 
     if(metric < KERNEL_INFINITY) {
+        unsigned char *src;
+
         *(int*)RTA_DATA(rta) = metric;
         rta = RTA_NEXT(rta, len);
         rta->rta_len = RTA_LENGTH(sizeof(int));
         rta->rta_type = RTA_OIF;
         *(int*)RTA_DATA(rta) = ifindex;
 
-        if(ipv4) {
-            rta = RTA_NEXT(rta, len);
-            rta->rta_len = RTA_LENGTH(sizeof(struct in_addr));
-            rta->rta_type = RTA_GATEWAY;
-            memcpy(RTA_DATA(rta), gate + 12, sizeof(struct in_addr));
-        } else {
-            rta = RTA_NEXT(rta, len);
-            rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
-            rta->rta_type = RTA_GATEWAY;
-            memcpy(RTA_DATA(rta), gate, sizeof(struct in6_addr));
-        }
+        ADD_IPARG(RTA_GATEWAY, gate);
+        src = preferred_source[ipv4];
+        if(src)
+            ADD_IPARG(RTA_PREFSRC, src);
     } else {
         *(int*)RTA_DATA(rta) = -1;
     }
     buf.nh.nlmsg_len = (char*)rta + rta->rta_len - buf.raw;
 
+#undef ADD_IPARG
+
     return netlink_talk(&buf.nh);
 }