nmcli: emit warning for unreachable gateways

src/nmcli/connections.c

@@ -5645,6 +5645,7 @@ connection_warnings(NmCli *nmc, NMConnection *connection)
     guint            i, found;
     const char      *id;
     const char      *deprecated;
+    gs_free char    *gw_warning = NULL;
 
     deprecated = nmc_connection_check_deprecated(NM_CONNECTION(connection));
     if (deprecated)
@@ -5673,6 +5674,10 @@ connection_warnings(NmCli *nmc, NMConnection *connection)
                      nm_connection_get_uuid(NM_CONNECTION(connection)),
                      found);
     }
+
+    gw_warning = nm_connection_get_unreachable_gateways_warning(connection, TRUE);
+    if (gw_warning)
+        nmc_printerr("Warning: %s.\n", gw_warning);
 }
 
 static void

src/tests/client/test-client.check-on-disk/test_005.expected

@@ -0,0 +1,15 @@
+size: 683
+location: src/tests/client/test-client.py:test_005()/1
+cmd: $NMCLI c add type ethernet ifname eth0 con-name con-xx1 ipv4.method manual ipv4.addresses 192.168.1.1/24 ipv4.gateway 192.168.2.1 ipv4.routes '192.168.4.4 192.168.4.1'
+lang: C
+returncode: 0
+stdout: 80 bytes
+>>>
+Connection 'con-xx1' (UUID-con-xx1-REPLACED-REPLACED-REPLA) successfully added.
+
+<<<
+stderr: 300 bytes
+>>>
+Warning: the following gateways are not directly reachable from any configured address or route: 192.168.2.1, 192.168.4.1. NetworkManager currently adds on-link routes for them automatically, but this will change in the future. Consider adding addresses or routes whose subnets cover these gateways.
+
+<<<

src/tests/client/test-client.py

@@ -2222,6 +2222,41 @@ class TestNmcli(unittest.TestCase):
             replace_stdout=replace_uuids,
         )
 
+    @nm_test
+    def test_005(self):
+        self.init_001()
+
+        replace_uuids = []
+
+        replace_uuids.append(
+            self.ctx.srv.ReplaceTextConUuid(
+                "con-xx1", "UUID-con-xx1-REPLACED-REPLACED-REPLA"
+            )
+        )
+
+        # Check the warning about unreachable gateways
+        self.call_nmcli(
+            [
+                "c",
+                "add",
+                "type",
+                "ethernet",
+                "ifname",
+                "eth0",
+                "con-name",
+                "con-xx1",
+                "ipv4.method",
+                "manual",
+                "ipv4.addresses",
+                "192.168.1.1/24",
+                "ipv4.gateway",
+                "192.168.2.1",
+                "ipv4.routes",
+                "192.168.4.4 192.168.4.1",
+            ],
+            replace_stdout=replace_uuids,
+        )
+
     @nm_test_no_dbus
     def test_offline(self):
         # Make sure we're not using D-Bus