platform: add oif argument to nm_platform_ip_route_get()

Analog to `ip route get $DST oif $IFACE`.

src/platform/nm-linux-platform.c

@@ -6033,6 +6033,7 @@ static NMPlatformError
 ip_route_get (NMPlatform *platform,
               int addr_family,
               gconstpointer address,
+              int oif_ifindex,
               NMPObject **out_route)
 {
 	const gboolean is_v4 = (addr_family == AF_INET);
@@ -6066,6 +6067,13 @@ ip_route_get (NMPlatform *platform,
 		if (!_nl_addattr_l (&req.n, sizeof (req), RTA_DST, address, addr_len))
 			nm_assert_not_reached ();
 
+		if (oif_ifindex > 0) {
+			gint32 ii = oif_ifindex;
+
+			if (!_nl_addattr_l (&req.n, sizeof (req), RTA_OIF, &ii, sizeof (ii)))
+				nm_assert_not_reached ();
+		}
+
 		seq_result = WAIT_FOR_NL_RESPONSE_RESULT_UNKNOWN;
 		nle = _nl_send_nlmsghdr (platform, &req.n, &seq_result, DELAYED_ACTION_RESPONSE_TYPE_ROUTE_GET, &route);
 		if (nle < 0) {

src/platform/nm-platform.c

@@ -3888,12 +3888,14 @@ NMPlatformError
 nm_platform_ip_route_get (NMPlatform *self,
                           int addr_family,
                           gconstpointer address /* in_addr_t or struct in6_addr */,
+                          int oif_ifindex,
                           NMPObject **out_route)
 {
 	nm_auto_nmpobj NMPObject *route = NULL;
 	NMPlatformError result;
 	char buf[NM_UTILS_INET_ADDRSTRLEN];
 	char buf_err[200];
+	char buf_oif[64];
 
 	_CHECK_SELF (self, klass, FALSE);
 
@@ -3901,9 +3903,10 @@ nm_platform_ip_route_get (NMPlatform *self,
 	g_return_val_if_fail (NM_IN_SET (addr_family, AF_INET,
 	                                              AF_INET6), NM_PLATFORM_ERROR_BUG);
 
-	_LOGT ("route: get IPv%c route for: %s",
+	_LOGT ("route: get IPv%c route for: %s%s",
 	       addr_family == AF_INET ? '4' : '6',
-	       inet_ntop (addr_family, address, buf, sizeof (buf)));
+	       inet_ntop (addr_family, address, buf, sizeof (buf)),
+	       oif_ifindex > 0 ? nm_sprintf_buf (buf_oif, " oif %d", oif_ifindex) : "");
 
 	if (!klass->ip_route_get)
 		result = NM_PLATFORM_ERROR_OPNOTSUPP;
@@ -3911,6 +3914,7 @@ nm_platform_ip_route_get (NMPlatform *self,
 		result = klass->ip_route_get (self,
 		                              addr_family,
 		                              address,
+		                              oif_ifindex,
 		                              &route);
 	}
 

src/platform/nm-platform.h

@@ -823,6 +823,7 @@ typedef struct {
 	NMPlatformError (*ip_route_get) (NMPlatform *self,
 	                                 int addr_family,
 	                                 gconstpointer address,
+	                                 int oif_ifindex,
 	                                 NMPObject **out_route);
 
 	gboolean (*check_support_kernel_extended_ifa_flags) (NMPlatform *);
@@ -1186,6 +1187,7 @@ gboolean nm_platform_ip_route_flush (NMPlatform *self,
 NMPlatformError nm_platform_ip_route_get (NMPlatform *self,
                                           int addr_family,
                                           gconstpointer address,
+                                          int oif_ifindex,
                                           NMPObject **out_route);
 
 const char *nm_platform_link_to_string (const NMPlatformLink *link, char *buf, gsize len);

src/platform/tests/test-route.c

@@ -409,6 +409,7 @@ test_ip_route_get (void)
 	result = nm_platform_ip_route_get (NM_PLATFORM_GET,
 	                                   AF_INET,
 	                                   &a,
+	                                   nmtst_get_rand_int () % 2 ? 0 : ifindex,
 	                                   &route);
 
 	g_assert (result == NM_PLATFORM_ERROR_SUCCESS);
@@ -417,6 +418,7 @@ test_ip_route_get (void)
 	g_assert (route->parent._ref_count == 1);
 	r = NMP_OBJECT_CAST_IP4_ROUTE (route);
 	g_assert (r->rt_cloned);
+	g_assert (r->ifindex == ifindex);
 	g_assert (r->network == a);
 	g_assert (r->plen == 32);
 

src/vpn/nm-vpn-connection.c

@@ -741,6 +741,7 @@ add_ip4_vpn_gateway_route (NMIP4Config *config,
 	if (nm_platform_ip_route_get (platform,
 	                              AF_INET,
 	                              &vpn_gw,
+	                              0,
 	                              (NMPObject **) &route_resolved) == NM_PLATFORM_ERROR_SUCCESS) {
 		const NMPlatformIP4Route *r = NMP_OBJECT_CAST_IP4_ROUTE (route_resolved);
 
@@ -811,6 +812,7 @@ add_ip6_vpn_gateway_route (NMIP6Config *config,
 	if (nm_platform_ip_route_get (platform,
 	                              AF_INET6,
 	                              vpn_gw,
+	                              0,
 	                              (NMPObject **) &route_resolved) == NM_PLATFORM_ERROR_SUCCESS) {
 		const NMPlatformIP6Route *r = NMP_OBJECT_CAST_IP6_ROUTE (route_resolved);