platform: use the "via" attribute in route NMPObject methods

Update the cmd_obj_hash_update(), cmd_obj_cmp(), cmd_obj_to_string()
NMPObject methods for IPv4 routes to consider the "via" attribute.

src/libnm-platform/nm-linux-platform.c

@@ -5828,9 +5828,11 @@ _nl_msg_new_route(uint16_t nlmsg_type, uint16_t nlmsg_flags, const NMPObject *ob
 
     /* We currently don't have need for multi-hop routes... */
     if (IS_IPv4) {
-        if (!obj->ip4_route.gateway && obj->ip4_route.via.addr_family) {
+        if (obj->ip4_route.gateway == INADDR_ANY && obj->ip4_route.via.addr_family != AF_UNSPEC) {
             struct rtvia *rtvia;
 
+            nm_assert(obj->ip4_route.via.addr_family == AF_INET6);
+
             rtvia = nla_data(nla_reserve(
                 msg,
                 RTA_VIA,

src/libnm-platform/nm-platform.c

@@ -7199,7 +7199,7 @@ nm_platform_ip4_route_to_string_full(const NMPlatformIP4Route     *route,
 {
     char *buf0;
     char  s_network[INET_ADDRSTRLEN];
-    char  s_gateway[INET_ADDRSTRLEN];
+    char  s_gateway[INET6_ADDRSTRLEN];
     char  s_pref_src[INET_ADDRSTRLEN];
     char  str_dev[30];
     char  str_mss[32];
@@ -7228,10 +7228,13 @@ nm_platform_ip4_route_to_string_full(const NMPlatformIP4Route     *route,
 
     inet_ntop(AF_INET, &route->network, s_network, sizeof(s_network));
 
-    if (route->gateway == 0)
+    if (route->gateway != INADDR_ANY) {
-        s_gateway[0] = '\0';
-    else
         inet_ntop(AF_INET, &route->gateway, s_gateway, sizeof(s_gateway));
+    } else if (route->via.addr_family == AF_INET6) {
+        inet_ntop(AF_INET6, route->via.addr.addr_ptr, s_gateway, sizeof(s_gateway));
+    } else {
+        s_gateway[0] = '\0';
+    }
 
     nm_strbuf_append(
         &buf,
@@ -8967,6 +8970,9 @@ nm_platform_ip4_route_hash_update(const NMPlatformIP4Route *obj,
                 nm_hash_update_vals(h,
                                     obj->ifindex,
                                     n_nexthops,
+                                    obj->via.addr_family,
+                                    obj->via.addr_family == AF_INET6 ? obj->via.addr.addr6
+                                                                     : in6addr_any,
                                     obj->gateway,
                                     _ip4_route_weight_normalize(n_nexthops, obj->weight, FALSE));
             }
@@ -9117,6 +9123,10 @@ nm_platform_ip4_route_cmp(const NMPlatformIP4Route *a,
             if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_ID) {
                 NM_CMP_FIELD(a, b, ifindex);
                 NM_CMP_FIELD(a, b, gateway);
+                NM_CMP_FIELD(a, b, via.addr_family);
+                if (a->via.addr_family == AF_INET6) {
+                    NM_CMP_FIELD_IN6ADDR(a, b, via.addr.addr6);
+                }
                 n_nexthops = nm_platform_ip4_route_get_n_nexthops(a);
                 NM_CMP_DIRECT(n_nexthops, nm_platform_ip4_route_get_n_nexthops(b));
                 NM_CMP_DIRECT(_ip4_route_weight_normalize(n_nexthops, a->weight, FALSE),
@@ -9142,6 +9152,10 @@ nm_platform_ip4_route_cmp(const NMPlatformIP4Route *a,
         NM_CMP_FIELD_UNSAFE(a, b, metric_any);
         NM_CMP_FIELD(a, b, metric);
         NM_CMP_FIELD(a, b, gateway);
+        NM_CMP_FIELD(a, b, via.addr_family);
+        if (a->via.addr_family == AF_INET6) {
+            NM_CMP_FIELD_IN6ADDR(a, b, via.addr.addr6);
+        }
         if (cmp_type == NM_PLATFORM_IP_ROUTE_CMP_TYPE_SEMANTICALLY) {
             n_nexthops = nm_platform_ip4_route_get_n_nexthops(a);
             NM_CMP_DIRECT(n_nexthops, nm_platform_ip4_route_get_n_nexthops(b));

src/libnm-platform/nm-platform.h

@@ -445,7 +445,7 @@ struct _NMPlatformIP4Route {
 
     /* RTA_VIA. Part of the primary key for a route. Allows a gateway for a
      * route to exist in a different address family.
-     * Only valid if: n_nexthops == 1, gateway == 0, via.family != 0
+     * Only valid if: n_nexthops == 1, gateway == 0, via.family != AF_UNSPEC
      */
     NMIPAddrTyped via;