policy: prefer device with default route to determine the hostname

In case two devices have the same hostname-priority, prefer the one
with the best default route. In this way, even if
hostname.only-from-default is set to FALSE globally, the behavior is
similar to the past when there is a device with the default route.

Previously, NMPolicy considered only the hostname-priority and the
activation order to build the DeviceHostnameInfo list. Now it has to
consider also the presence of the default route, which depends on the
address family. Therefore, now there is a DeviceHostnameInfo for each
[device,address_family] combination.

1 files changed, 66 insertions, 70 deletions

diff --git a/src/nm-policy.c b/src/nm-policy.c
index cda22b1030..97d7e92e2c 100644
--- a/src/nm-policy.c
+++ b/src/nm-policy.c
@@ -640,14 +640,8 @@ typedef struct {
     int       priority;
     bool      from_dhcp : 1;
     bool      from_dns : 1;
-
-    union {
-        struct {
-            bool ip_6;
-            bool ip_4;
-        };
-        bool ip_x[2];
-    };
+    bool      IS_IPv4 : 1;
+    bool      is_default : 1;
 } DeviceHostnameInfo;
 
 static int
@@ -657,6 +651,7 @@ device_hostname_info_compare(gconstpointer a, gconstpointer b)
     const DeviceHostnameInfo *info2 = b;
 
     NM_CMP_FIELD(info1, info2, priority);
+    NM_CMP_FIELD_UNSAFE(info2, info1, is_default);
 
     return 0;
 }
@@ -726,6 +721,8 @@ build_device_hostname_infos(NMPolicy *self)
         DeviceHostnameInfo *info;
         NMDevice *          device;
         gboolean            only_from_default;
+        gboolean            is_default;
+        int                 IS_IPv4;
 
         device = nm_active_connection_get_device(ac);
         if (!device)
@@ -733,23 +730,28 @@ build_device_hostname_infos(NMPolicy *self)
 
         only_from_default =
             device_get_hostname_property_boolean(device, NM_SETTING_HOSTNAME_ONLY_FROM_DEFAULT);
-        if (only_from_default && ac != priv->default_ac4 && ac != priv->default_ac6)
-            continue;
 
-        if (!array)
-            array = g_array_sized_new(FALSE, FALSE, sizeof(DeviceHostnameInfo), 4);
+        for (IS_IPv4 = 1; IS_IPv4 >= 0; IS_IPv4--) {
+            is_default = (ac == (IS_IPv4 ? priv->default_ac4 : priv->default_ac6));
+            if (only_from_default && !is_default)
+                continue;
 
-        info  = nm_g_array_append_new(array, DeviceHostnameInfo);
-        *info = (DeviceHostnameInfo){
-            .device   = device,
-            .priority = device_get_hostname_priority(device),
-            .from_dhcp =
-                device_get_hostname_property_boolean(device, NM_SETTING_HOSTNAME_FROM_DHCP),
-            .from_dns =
-                device_get_hostname_property_boolean(device, NM_SETTING_HOSTNAME_FROM_DNS_LOOKUP),
-            .ip_4 = priv->default_ac4 || !only_from_default,
-            .ip_6 = priv->default_ac6 || !only_from_default,
-        };
+            if (!array)
+                array = g_array_sized_new(FALSE, FALSE, sizeof(DeviceHostnameInfo), 4);
+
+            info  = nm_g_array_append_new(array, DeviceHostnameInfo);
+            *info = (DeviceHostnameInfo){
+                .device   = device,
+                .priority = device_get_hostname_priority(device),
+                .from_dhcp =
+                    device_get_hostname_property_boolean(device, NM_SETTING_HOSTNAME_FROM_DHCP),
+                .from_dns =
+                    device_get_hostname_property_boolean(device,
+                                                         NM_SETTING_HOSTNAME_FROM_DNS_LOOKUP),
+                .IS_IPv4    = IS_IPv4,
+                .is_default = is_default,
+            };
+        }
     }
 
     if (array && array->len > 1) {
@@ -796,7 +798,7 @@ update_system_hostname(NMPolicy *self, const char *msg)
     gs_unref_array GArray *infos = NULL;
     DeviceHostnameInfo *   info;
     guint                  i;
-    int                    IS_IPv4;
+    int                    addr_family;
 
     g_return_if_fail(self != NULL);
 
@@ -854,65 +856,59 @@ update_system_hostname(NMPolicy *self, const char *msg)
         for (i = 0; i < infos->len; i++) {
             info = &g_array_index(infos, DeviceHostnameInfo, i);
             _LOGT(LOGD_DNS,
-                  "  - prio:%4d ipv:%c%c dhcp:%d dns:%d dev:%s",
+                  "  - prio:%5d ipv%c%s %s %s dev:%s",
                   info->priority,
-                  info->ip_4 ? '4' : '-',
-                  info->ip_6 ? '6' : '-',
-                  info->from_dhcp,
-                  info->from_dns,
+                  info->IS_IPv4 ? '4' : '6',
+                  info->is_default ? " (def)" : "      ",
+                  info->from_dhcp ? "dhcp " : "     ",
+                  info->from_dns ? "dns " : "    ",
                   nm_device_get_iface(info->device));
         }
     }
 
     for (i = 0; infos && i < infos->len; i++) {
-        info = &g_array_index(infos, DeviceHostnameInfo, i);
+        info        = &g_array_index(infos, DeviceHostnameInfo, i);
+        addr_family = info->IS_IPv4 ? AF_INET : AF_INET6;
         g_signal_handlers_disconnect_by_func(info->device, device_dns_lookup_done, self);
-        for (IS_IPv4 = 1; IS_IPv4 >= 0; IS_IPv4--) {
-            const int addr_family = IS_IPv4 ? AF_INET : AF_INET6;
-
-            if (info->from_dhcp && info->ip_x[IS_IPv4]) {
-                dhcp_config = nm_device_get_dhcp_config(info->device, addr_family);
-                if (dhcp_config) {
-                    dhcp_hostname =
-                        nm_dhcp_config_get_option(dhcp_config, IS_IPv4 ? "host_name" : "fqdn_fqdn");
-                    if (dhcp_hostname && dhcp_hostname[0]) {
-                        p = nm_str_skip_leading_spaces(dhcp_hostname);
-                        if (p[0]) {
-                            _set_hostname(self, p, IS_IPv4 ? "from DHCPv4" : "from DHCPv6");
-                            priv->dhcp_hostname = TRUE;
-                            return;
-                        }
-                        _LOGW(LOGD_DNS,
-                              "set-hostname: DHCPv%c-provided hostname '%s' looks invalid; "
-                              "ignoring it",
-                              nm_utils_addr_family_to_char(addr_family),
-                              dhcp_hostname);
+
+        if (info->from_dhcp) {
+            dhcp_config = nm_device_get_dhcp_config(info->device, addr_family);
+            if (dhcp_config) {
+                dhcp_hostname =
+                    nm_dhcp_config_get_option(dhcp_config,
+                                              info->IS_IPv4 ? "host_name" : "fqdn_fqdn");
+                if (dhcp_hostname && dhcp_hostname[0]) {
+                    p = nm_str_skip_leading_spaces(dhcp_hostname);
+                    if (p[0]) {
+                        _set_hostname(self, p, info->IS_IPv4 ? "from DHCPv4" : "from DHCPv6");
+                        priv->dhcp_hostname = TRUE;
+                        return;
                     }
+                    _LOGW(LOGD_DNS,
+                          "set-hostname: DHCPv%c-provided hostname '%s' looks invalid; "
+                          "ignoring it",
+                          nm_utils_addr_family_to_char(addr_family),
+                          dhcp_hostname);
                 }
             }
         }
 
         if (priv->hostname_mode != NM_POLICY_HOSTNAME_MODE_DHCP) {
-            for (IS_IPv4 = 1; IS_IPv4 >= 0; IS_IPv4--) {
-                const int addr_family = IS_IPv4 ? AF_INET : AF_INET6;
-
-                if (info->from_dns && info->ip_x[IS_IPv4]) {
-                    const char *result;
-                    gboolean    wait = FALSE;
-
-                    result =
-                        nm_device_get_hostname_from_dns_lookup(info->device, addr_family, &wait);
-                    if (result) {
-                        _set_hostname(self, result, "from address lookup");
-                        return;
-                    }
-                    if (wait) {
-                        g_signal_connect(info->device,
-                                         NM_DEVICE_DNS_LOOKUP_DONE,
-                                         (GCallback) device_dns_lookup_done,
-                                         self);
-                        return;
-                    }
+            if (info->from_dns) {
+                const char *result;
+                gboolean    wait = FALSE;
+
+                result = nm_device_get_hostname_from_dns_lookup(info->device, addr_family, &wait);
+                if (result) {
+                    _set_hostname(self, result, "from address lookup");
+                    return;
+                }
+                if (wait) {
+                    g_signal_connect(info->device,
+                                     NM_DEVICE_DNS_LOOKUP_DONE,
+                                     (GCallback) device_dns_lookup_done,
+                                     self);
+                    return;
                 }
             }
         }