policy: use the hostname settingbg/hostname-setting-rh1766944

Rework update_system_hostname() to use the new properties from the
hostname setting.

In the default configuration where all the 3 boolean properties
hostname.{from-dhcp,from-dns,only-from-default} are true, the behavior
is the same as before.

3 files changed, 464 insertions, 76 deletions

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index b905855cf5..98b4d339e4 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -206,6 +206,23 @@ typedef struct {
     NMEthtoolRingState *    ring;
 } EthtoolState;
 
+typedef enum {
+    RESOLVER_WAIT_ADDRESS = 0,
+    RESOLVER_IN_PROGRESS,
+    RESOLVER_DONE,
+} ResolverState;
+
+typedef struct {
+    ResolverState state;
+    GResolver *   resolver;
+    GInetAddress *address;
+    GCancellable *cancellable;
+    char *        hostname;
+    NMDevice *    device;
+    guint         timeout_id; /* Used when waiting for the address */
+    int           addr_family;
+} HostnameResolver;
+
 /*****************************************************************************/
 
 enum {
@@ -218,6 +235,7 @@ enum {
     REMOVED,
     RECHECK_AUTO_ACTIVATE,
     RECHECK_ASSUME,
+    DNS_LOOKUP_DONE,
     LAST_SIGNAL,
 };
 static guint signals[LAST_SIGNAL] = {0};
@@ -325,6 +343,14 @@ typedef struct _NMDevicePrivate {
     int auth_retries;
 
     union {
+        struct {
+            HostnameResolver *hostname_resolver_6;
+            HostnameResolver *hostname_resolver_4;
+        };
+        HostnameResolver *hostname_resolver_x[2];
+    };
+
+    union {
         const guint8 hw_addr_len; /* read-only */
         guint8       hw_addr_len_;
     };
@@ -866,6 +892,22 @@ static NM_UTILS_LOOKUP_STR_DEFINE(mtu_source_to_str,
 
 /*****************************************************************************/
 
+static void
+_hostname_resolver_free(HostnameResolver *resolver)
+{
+    if (!resolver)
+        return;
+
+    nm_clear_g_source(&resolver->timeout_id);
+    nm_clear_g_cancellable(&resolver->cancellable);
+    nm_g_object_unref(resolver->resolver);
+    nm_g_object_unref(resolver->address);
+    g_free(resolver->hostname);
+    nm_g_slice_free(resolver);
+}
+
+/*****************************************************************************/
+
 static NMSettingIP6ConfigPrivacy
 _ip6_privacy_clamp(NMSettingIP6ConfigPrivacy use_tempaddr)
 {
@@ -15618,6 +15660,7 @@ static void
 _cleanup_generic_pre(NMDevice *self, CleanupType cleanup_type)
 {
     NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE(self);
+    guint            i;
 
     _cancel_activation(self);
 
@@ -15642,6 +15685,9 @@ _cleanup_generic_pre(NMDevice *self, CleanupType cleanup_type)
 
     nm_clear_pointer(&priv->shared_ip_handle, nm_netns_shared_ip_release);
 
+    for (i = 0; i < 2; i++)
+        nm_clear_pointer(&priv->hostname_resolver_x[i], _hostname_resolver_free);
+
     _cleanup_ip_pre(self, AF_INET, cleanup_type);
     _cleanup_ip_pre(self, AF_INET6, cleanup_type);
 }
@@ -17467,6 +17513,178 @@ nm_device_auth_retries_try_next(NMDevice *self)
     return TRUE;
 }
 
+static void
+hostname_dns_lookup_callback(GObject *source, GAsyncResult *result, gpointer user_data)
+{
+    HostnameResolver *resolver;
+    NMDevice *        self;
+    gs_free char *    hostname  = NULL;
+    gs_free char *    addr_str  = NULL;
+    gs_free_error GError *error = NULL;
+
+    hostname = g_resolver_lookup_by_address_finish(G_RESOLVER(source), result, &error);
+    if (g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        return;
+
+    resolver           = user_data;
+    self               = resolver->device;
+    resolver->state    = RESOLVER_DONE;
+    resolver->hostname = g_strdup(hostname);
+
+    _LOGD(LOGD_DNS,
+          "hostname-from-dns: lookup done for %s, result %s%s%s",
+          (addr_str = g_inet_address_to_string(resolver->address)),
+          NM_PRINT_FMT_QUOTE_STRING(hostname));
+
+    nm_clear_g_cancellable(&resolver->cancellable);
+    g_signal_emit(self, signals[DNS_LOOKUP_DONE], 0);
+}
+
+static gboolean
+hostname_dns_address_timeout(gpointer user_data)
+{
+    HostnameResolver *resolver = user_data;
+    NMDevice *        self     = resolver->device;
+
+    g_return_val_if_fail(NM_IS_DEVICE(self), G_SOURCE_REMOVE);
+
+    nm_assert(resolver->state == RESOLVER_WAIT_ADDRESS);
+    nm_assert(!resolver->address);
+    nm_assert(!resolver->cancellable);
+
+    _LOGT(LOGD_DNS,
+          "hostname-from-dns: timed out while waiting IPv%c address",
+          nm_utils_addr_family_to_char(resolver->addr_family));
+
+    resolver->timeout_id = 0;
+    resolver->state      = RESOLVER_DONE;
+    g_signal_emit(self, signals[DNS_LOOKUP_DONE], 0);
+
+    return G_SOURCE_REMOVE;
+}
+
+/* return value is valid only immediately */
+const char *
+nm_device_get_hostname_from_dns_lookup(NMDevice *self, int addr_family, gboolean *out_wait)
+{
+    NMDevicePrivate * priv;
+    const int         IS_IPv4 = NM_IS_IPv4(addr_family);
+    HostnameResolver *resolver;
+    NMIPConfig *      ip_config;
+    const char *      method;
+    gboolean          address_changed         = FALSE;
+    gs_unref_object GInetAddress *new_address = NULL;
+
+    g_return_val_if_fail(NM_IS_DEVICE(self), NULL);
+    priv = NM_DEVICE_GET_PRIVATE(self);
+
+    /* If the device is not supposed to have addresses,
+     * return an immediate empty result.*/
+    method = nm_device_get_effective_ip_config_method(self, addr_family);
+    if (IS_IPv4) {
+        if (NM_IN_STRSET(method, NM_SETTING_IP4_CONFIG_METHOD_DISABLED)) {
+            nm_clear_pointer(&priv->hostname_resolver_x[IS_IPv4], _hostname_resolver_free);
+            NM_SET_OUT(out_wait, FALSE);
+            return NULL;
+        }
+    } else {
+        if (NM_IN_STRSET(method,
+                         NM_SETTING_IP6_CONFIG_METHOD_DISABLED,
+                         NM_SETTING_IP6_CONFIG_METHOD_IGNORE)) {
+            nm_clear_pointer(&priv->hostname_resolver_x[IS_IPv4], _hostname_resolver_free);
+            NM_SET_OUT(out_wait, FALSE);
+            return NULL;
+        }
+    }
+
+    resolver = priv->hostname_resolver_x[IS_IPv4];
+    if (!resolver) {
+        resolver  = g_slice_new(HostnameResolver);
+        *resolver = (HostnameResolver){
+            .resolver    = g_resolver_get_default(),
+            .device      = self,
+            .addr_family = addr_family,
+            .state       = RESOLVER_WAIT_ADDRESS,
+        };
+        priv->hostname_resolver_x[IS_IPv4] = resolver;
+    }
+
+    /* Determine the first address of the interface and
+     * whether it changed from the previous lookup */
+    ip_config = priv->ip_config_x[IS_IPv4];
+    if (ip_config) {
+        const NMPlatformIPAddress *addr;
+
+        addr = nm_ip_config_get_first_address(ip_config);
+        if (addr) {
+            new_address = g_inet_address_new_from_bytes(addr->address_ptr,
+                                                        IS_IPv4 ? G_SOCKET_FAMILY_IPV4
+                                                                : G_SOCKET_FAMILY_IPV6);
+        }
+    }
+
+    if (new_address && resolver->address) {
+        if (!g_inet_address_equal(new_address, resolver->address))
+            address_changed = TRUE;
+    } else if (new_address != resolver->address)
+        address_changed = TRUE;
+
+    {
+        gs_free char *old_str = NULL;
+        gs_free char *new_str = NULL;
+
+        _LOGT(LOGD_DNS,
+              "hostname-from-dns: ipv%c resolver state %d, old address %s, new address %s",
+              nm_utils_addr_family_to_char(resolver->addr_family),
+              resolver->state,
+              resolver->address ? (old_str = g_inet_address_to_string(resolver->address))
+                                : "(null)",
+              new_address ? (new_str = g_inet_address_to_string(new_address)) : "(null)");
+    }
+
+    /* In every state, if the address changed, we restart
+     * the resolution with the new address */
+    if (address_changed) {
+        nm_clear_g_cancellable(&resolver->cancellable);
+        nm_g_object_unref(resolver->address);
+        resolver->state = RESOLVER_WAIT_ADDRESS;
+    }
+
+    if (address_changed && new_address) {
+        gs_free char *str = NULL;
+
+        _LOGT(LOGD_DNS,
+              "hostname-from-dns: starting lookup for address %s",
+              (str = g_inet_address_to_string(new_address)));
+
+        resolver->state       = RESOLVER_IN_PROGRESS;
+        resolver->cancellable = g_cancellable_new();
+        resolver->address     = g_steal_pointer(&new_address);
+        g_resolver_lookup_by_address_async(resolver->resolver,
+                                           resolver->address,
+                                           resolver->cancellable,
+                                           hostname_dns_lookup_callback,
+                                           resolver);
+        nm_clear_g_source(&resolver->timeout_id);
+    }
+
+    switch (resolver->state) {
+    case RESOLVER_WAIT_ADDRESS:
+        if (!resolver->timeout_id)
+            resolver->timeout_id = g_timeout_add(30000, hostname_dns_address_timeout, resolver);
+        NM_SET_OUT(out_wait, TRUE);
+        return NULL;
+    case RESOLVER_IN_PROGRESS:
+        NM_SET_OUT(out_wait, TRUE);
+        return NULL;
+    case RESOLVER_DONE:
+        NM_SET_OUT(out_wait, FALSE);
+        return resolver->hostname;
+    }
+
+    return nm_assert_unreachable_val(NULL);
+}
+
 /*****************************************************************************/
 
 static const char *
@@ -18644,6 +18862,16 @@ nm_device_class_init(NMDeviceClass *klass)
                                            NULL,
                                            G_TYPE_NONE,
                                            0);
+
+    signals[DNS_LOOKUP_DONE] = g_signal_new(NM_DEVICE_DNS_LOOKUP_DONE,
+                                            G_OBJECT_CLASS_TYPE(object_class),
+                                            G_SIGNAL_RUN_FIRST,
+                                            0,
+                                            NULL,
+                                            NULL,
+                                            NULL,
+                                            G_TYPE_NONE,
+                                            0);
 }
 
 /* Connection defaults from plugins */
diff --git a/src/devices/nm-device.h b/src/devices/nm-device.h
index d29a6a1506..c330411bc4 100644
--- a/src/devices/nm-device.h
+++ b/src/devices/nm-device.h
@@ -116,6 +116,7 @@ nm_device_state_reason_check(NMDeviceStateReason reason)
 #define NM_DEVICE_HAS_PENDING_ACTION "has-pending-action" /* Internal only */
 
 /* Internal signals */
+#define NM_DEVICE_DNS_LOOKUP_DONE       "dns-lookup-done"
 #define NM_DEVICE_IP4_CONFIG_CHANGED    "ip4-config-changed"
 #define NM_DEVICE_IP6_CONFIG_CHANGED    "ip6-config-changed"
 #define NM_DEVICE_IP6_PREFIX_DELEGATED  "ip6-prefix-delegated"
@@ -863,4 +864,7 @@ const char *nm_device_state_reason_to_str(NMDeviceStateReason reason);
 
 gboolean nm_device_is_vpn(NMDevice *self);
 
+const char *
+nm_device_get_hostname_from_dns_lookup(NMDevice *self, int addr_family, gboolean *out_pending);
+
 #endif /* __NETWORKMANAGER_DEVICE_H__ */
diff --git a/src/nm-policy.c b/src/nm-policy.c
index 5a14a663ee..bf54ede1a2 100644
--- a/src/nm-policy.c
+++ b/src/nm-policy.c
@@ -117,6 +117,8 @@ _PRIV_TO_SELF(NMPolicyPrivate *priv)
 /*****************************************************************************/
 
 #define _NMLOG_PREFIX_NAME "policy"
+#undef _NMLOG_ENABLED
+#define _NMLOG_ENABLED(level, domain) (nm_logging_enabled((level), (domain)))
 #define _NMLOG(level, domain, ...)                                         \
     G_STMT_START                                                           \
     {                                                                      \
@@ -131,6 +133,7 @@ _PRIV_TO_SELF(NMPolicyPrivate *priv)
 
 /*****************************************************************************/
 
+static void      update_system_hostname(NMPolicy *self, const char *msg);
 static void      schedule_activate_all(NMPolicy *self);
 static void      schedule_activate_check(NMPolicy *self, NMDevice *device);
 static NMDevice *get_default_device(NMPolicy *self, int addr_family);
@@ -671,20 +674,168 @@ lookup_by_address(NMPolicy *self)
                                        self);
 }
 
+typedef struct {
+    NMDevice *device;
+    int       priority;
+    bool      from_dhcp : 1;
+    bool      from_dns : 1;
+
+    union {
+        struct {
+            bool ip_6;
+            bool ip_4;
+        };
+        bool ip_x[2];
+    };
+} DeviceHostnameInfo;
+
+static int
+device_hostname_info_compare(gconstpointer a, gconstpointer b)
+{
+    const DeviceHostnameInfo *info1 = a;
+    const DeviceHostnameInfo *info2 = b;
+
+    NM_CMP_FIELD(info1, info2, priority);
+
+    return 0;
+}
+
+NM_CON_DEFAULT_NOP("hostname.from-dhcp");
+NM_CON_DEFAULT_NOP("hostname.from-dns-lookup");
+NM_CON_DEFAULT_NOP("hostname.only-from-default");
+
+static gboolean
+device_get_hostname_property_boolean(NMDevice *device, const char *name)
+{
+    NMSettingHostname *s_hostname;
+    char               buf[128];
+    int                value;
+
+    nm_assert(NM_IN_STRSET(name,
+                           NM_SETTING_HOSTNAME_FROM_DHCP,
+                           NM_SETTING_HOSTNAME_FROM_DNS_LOOKUP,
+                           NM_SETTING_HOSTNAME_ONLY_FROM_DEFAULT));
+
+    s_hostname = nm_device_get_applied_setting(device, NM_TYPE_SETTING_HOSTNAME);
+
+    if (s_hostname) {
+        g_object_get(s_hostname, name, &value, NULL);
+        if (NM_IN_SET(value, NM_TERNARY_FALSE, NM_TERNARY_TRUE))
+            return value;
+    }
+
+    return nm_config_data_get_connection_default_int64(NM_CONFIG_GET_DATA,
+                                                       nm_sprintf_buf(buf, "hostname.%s", name),
+                                                       device,
+                                                       NM_TERNARY_FALSE,
+                                                       NM_TERNARY_TRUE,
+                                                       NM_TERNARY_TRUE);
+}
+
+static int
+device_get_hostname_priority(NMDevice *device)
+{
+    NMSettingHostname *s_hostname;
+    int                priority;
+
+    s_hostname = nm_device_get_applied_setting(device, NM_TYPE_SETTING_HOSTNAME);
+    if (s_hostname) {
+        priority = nm_setting_hostname_get_priority(s_hostname);
+        if (priority != 0)
+            return priority;
+    }
+
+    return nm_config_data_get_connection_default_int64(NM_CONFIG_GET_DATA,
+                                                       NM_CON_DEFAULT("hostname.priority"),
+                                                       device,
+                                                       G_MININT,
+                                                       G_MAXINT,
+                                                       100);
+}
+
+static GArray *
+build_device_hostname_infos(NMPolicy *self)
+{
+    NMPolicyPrivate *   priv = NM_POLICY_GET_PRIVATE(self);
+    const CList *       tmp_clist;
+    NMActiveConnection *ac;
+    GArray *            array = NULL;
+
+    nm_manager_for_each_active_connection (priv->manager, ac, tmp_clist) {
+        DeviceHostnameInfo *info;
+        NMDevice *          device;
+        gboolean            only_from_default;
+
+        device = nm_active_connection_get_device(ac);
+        if (!device)
+            continue;
+
+        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);
+
+        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->len > 1) {
+        const DeviceHostnameInfo *info0;
+        guint                     i;
+
+        g_array_sort(array, device_hostname_info_compare);
+
+        info0 = &g_array_index(array, DeviceHostnameInfo, 0);
+        if (info0->priority < 0) {
+            for (i = 1; i < array->len; i++) {
+                const DeviceHostnameInfo *info = &g_array_index(array, DeviceHostnameInfo, i);
+
+                if (info->priority > info0->priority) {
+                    g_array_set_size(array, i);
+                    break;
+                }
+            }
+        }
+    }
+
+    return array;
+}
+
+static void
+device_dns_lookup_done(NMDevice *device, gpointer user_data)
+{
+    NMPolicy *self = user_data;
+
+    g_signal_handlers_disconnect_by_func(device, device_dns_lookup_done, self);
+
+    update_system_hostname(self, "lookup finished");
+}
+
 static void
 update_system_hostname(NMPolicy *self, const char *msg)
 {
-    NMPolicyPrivate *           priv = NM_POLICY_GET_PRIVATE(self);
-    const char *                configured_hostname;
-    gs_free char *              temp_hostname = NULL;
-    const char *                dhcp_hostname, *p;
-    NMIP4Config *               ip4_config;
-    NMIP6Config *               ip6_config;
-    gboolean                    external_hostname = FALSE;
-    const NMPlatformIP4Address *addr4;
-    const NMPlatformIP6Address *addr6;
-    NMDevice *                  device;
-    NMDhcpConfig *              dhcp_config;
+    NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE(self);
+    const char *     configured_hostname;
+    gs_free char *   temp_hostname = NULL;
+    const char *     dhcp_hostname, *p;
+    gboolean         external_hostname = FALSE;
+    NMDhcpConfig *   dhcp_config;
+    gs_unref_array GArray *infos = NULL;
+    DeviceHostnameInfo *   info;
+    guint                  i;
+    int                    IS_IPv4;
 
     g_return_if_fail(self != NULL);
 
@@ -724,10 +875,9 @@ update_system_hostname(NMPolicy *self, const char *msg)
     /* Hostname precedence order:
      *
      * 1) a configured hostname (from settings)
-     * 2) automatic hostname from the default device's config (DHCP, VPN, etc)
-     * 3) the last hostname set outside NM
-     * 4) reverse-DNS of the best device's IPv4 address
-     *
+     * 2) automatic hostname from DHCP of eligible interfaces
+     * 3) reverse-DNS lookup of the first address on eligible interfaces
+     * 4) the last hostname set outside NM
      */
 
     /* Try a persistent hostname first */
@@ -738,40 +888,73 @@ update_system_hostname(NMPolicy *self, const char *msg)
         return;
     }
 
-    if (priv->default_ac4) {
-        /* Grab a hostname out of the device's DHCP4 config */
-        dhcp_config = nm_device_get_dhcp_config(get_default_device(self, AF_INET), AF_INET);
-        if (dhcp_config) {
-            dhcp_hostname = nm_dhcp_config_get_option(dhcp_config, "host_name");
-            if (dhcp_hostname && dhcp_hostname[0]) {
-                p = nm_str_skip_leading_spaces(dhcp_hostname);
-                if (p[0]) {
-                    _set_hostname(self, p, "from DHCPv4");
-                    priv->dhcp_hostname = TRUE;
-                    return;
+    infos = build_device_hostname_infos(self);
+
+    if (infos && _LOGT_ENABLED(LOGD_DNS)) {
+        _LOGT(LOGD_DNS, "device hostname info:");
+        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",
+                  info->priority,
+                  info->ip_4 ? '4' : '-',
+                  info->ip_6 ? '6' : '-',
+                  info->from_dhcp,
+                  info->from_dns,
+                  nm_device_get_iface(info->device));
+        }
+    }
+
+    for (i = 0; infos && i < infos->len; i++) {
+        info = &g_array_index(infos, DeviceHostnameInfo, i);
+        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);
+                    }
                 }
-                _LOGW(LOGD_DNS,
-                      "set-hostname: DHCPv4-provided hostname '%s' looks invalid; ignoring it",
-                      dhcp_hostname);
             }
         }
-    }
 
-    if (priv->default_ac6) {
-        /* Grab a hostname out of the device's DHCP6 config */
-        dhcp_config = nm_device_get_dhcp_config(get_default_device(self, AF_INET6), AF_INET6);
-        if (dhcp_config) {
-            dhcp_hostname = nm_dhcp_config_get_option(dhcp_config, "fqdn_fqdn");
-            if (dhcp_hostname && dhcp_hostname[0]) {
-                p = nm_str_skip_leading_spaces(dhcp_hostname);
-                if (p[0]) {
-                    _set_hostname(self, p, "from DHCPv6");
-                    priv->dhcp_hostname = TRUE;
-                    return;
+        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_INET6 : AF_INET;
+
+                if (info->from_dns && info->ip_x[IS_IPv4]) {
+                    const char *result;
+                    gboolean    wait;
+
+                    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;
+                    }
                 }
-                _LOGW(LOGD_DNS,
-                      "set-hostname: DHCPv6-provided hostname '%s' looks invalid; ignoring it",
-                      dhcp_hostname);
             }
         }
     }
@@ -795,14 +978,6 @@ update_system_hostname(NMPolicy *self, const char *msg)
 
     priv->dhcp_hostname = FALSE;
 
-    if (!priv->default_ac4 && !priv->default_ac6) {
-        /* No best device; fall back to the last hostname set externally
-         * to NM or if there wasn't one, 'localhost.localdomain'
-         */
-        _set_hostname(self, priv->orig_hostname, "no default device");
-        return;
-    }
-
     /* If no automatically-configured hostname, try using the last hostname
      * set externally to NM
      */
@@ -811,30 +986,7 @@ update_system_hostname(NMPolicy *self, const char *msg)
         return;
     }
 
-    /* No configured hostname, no automatically determined hostname, and no
-     * bootup hostname. Start reverse DNS of the current IPv4 or IPv6 address.
-     */
-    device     = get_default_device(self, AF_INET);
-    ip4_config = device ? nm_device_get_ip4_config(device) : NULL;
-
-    device     = get_default_device(self, AF_INET6);
-    ip6_config = device ? nm_device_get_ip6_config(device) : NULL;
-
-    if (ip4_config && (addr4 = nm_ip4_config_get_first_address(ip4_config))) {
-        g_clear_object(&priv->lookup.addr);
-        priv->lookup.addr =
-            g_inet_address_new_from_bytes((guint8 *) &addr4->address, G_SOCKET_FAMILY_IPV4);
-    } else if (ip6_config && (addr6 = nm_ip6_config_get_first_address(ip6_config))) {
-        g_clear_object(&priv->lookup.addr);
-        priv->lookup.addr =
-            g_inet_address_new_from_bytes((guint8 *) &addr6->address, G_SOCKET_FAMILY_IPV6);
-    } else {
-        /* No valid IP config; fall back to localhost.localdomain */
-        _set_hostname(self, NULL, "no IP config");
-        return;
-    }
-
-    lookup_by_address(self);
+    _set_hostname(self, NULL, "no hostname found");
 }
 
 static void
@@ -1796,6 +1948,8 @@ device_state_changed(NMDevice *          device,
 
     switch (new_state) {
     case NM_DEVICE_STATE_FAILED:
+        g_signal_handlers_disconnect_by_func(device, device_dns_lookup_done, self);
+
         /* Mark the connection invalid if it failed during activation so that
          * it doesn't get automatically chosen over and over and over again.
          */
@@ -1934,6 +2088,8 @@ device_state_changed(NMDevice *          device,
         ip6_remove_device_prefix_delegations(self, device);
         break;
     case NM_DEVICE_STATE_DISCONNECTED:
+        g_signal_handlers_disconnect_by_func(device, device_dns_lookup_done, self);
+
         /* Reset retry counts for a device's connections when carrier on; if cable
          * was unplugged and plugged in again, we should try to reconnect.
          */