core: preserve the domain when system hostname is truncatedbg/dhcp-overlong-hostname

Pass the full hostname to the DNS manager, so that the domain gets
added to resolv.conf even when the hostname was truncated.

Note that "hostname" argument for plugins's update() function is
currently unused. Don't remove that because it can be potentially
useful to set a global search domain based on the hostname, but change
it to carry the domain directly.

7 files changed, 44 insertions, 38 deletions

diff --git a/src/core/dns/nm-dns-dnsmasq.c b/src/core/dns/nm-dns-dnsmasq.c
index 1be42b958d..43426882ed 100644
--- a/src/core/dns/nm-dns-dnsmasq.c
+++ b/src/core/dns/nm-dns-dnsmasq.c
@@ -848,7 +848,7 @@ static GVariant *
 create_update_args(NMDnsDnsmasq            *self,
                    const NMGlobalDnsConfig *global_config,
                    const CList             *ip_data_lst_head,
-                   const char              *hostname)
+                   const char              *hostdomain)
 {
     GVariantBuilder          servers;
     const NMDnsConfigIPData *ip_data;
@@ -1124,7 +1124,7 @@ static gboolean
 update(NMDnsPlugin             *plugin,
        const NMGlobalDnsConfig *global_config,
        const CList             *ip_data_lst_head,
-       const char              *hostname,
+       const char              *hostdomain,
        GError                 **error)
 {
     NMDnsDnsmasq        *self = NM_DNS_DNSMASQ(plugin);
@@ -1135,7 +1135,7 @@ update(NMDnsPlugin             *plugin,
 
     nm_clear_pointer(&priv->set_server_ex_args, g_variant_unref);
     priv->set_server_ex_args =
-        g_variant_ref_sink(create_update_args(self, global_config, ip_data_lst_head, hostname));
+        g_variant_ref_sink(create_update_args(self, global_config, ip_data_lst_head, hostdomain));
 
     send_dnsmasq_update(self);
     return TRUE;
diff --git a/src/core/dns/nm-dns-manager.c b/src/core/dns/nm-dns-manager.c
index 50c774c144..566f3d6626 100644
--- a/src/core/dns/nm-dns-manager.c
+++ b/src/core/dns/nm-dns-manager.c
@@ -26,6 +26,7 @@
 
 #include "libnm-core-intern/nm-core-internal.h"
 #include "libnm-glib-aux/nm-str-buf.h"
+#include "libnm-systemd-shared/nm-sd-utils-shared.h"
 
 #include "NetworkManagerUtils.h"
 #include "devices/nm-device.h"
@@ -97,7 +98,7 @@ typedef struct {
 
     bool config_changed : 1;
 
-    char *hostname;
+    char *hostdomain;
     guint updates_queue;
 
     guint8 hash[HASH_LEN];      /* SHA1 hash of current DNS config */
@@ -1260,24 +1261,8 @@ _collect_resolv_conf_data(NMDnsManager      *self,
         }
     }
 
-    /* If the hostname is a FQDN ("dcbw.example.com"), then add the domain part of it
-     * ("example.com") to the searches list, to ensure that we can still resolve its
-     * non-FQ form ("dcbw") too. (Also, if there are no other search domains specified,
-     * this makes a good default.) However, if the hostname is the top level of a domain
-     * (eg, "example.com"), then use the hostname itself as the search (since the user is
-     * unlikely to want "com" as a search domain).
-     */
-    if (priv->hostname) {
-        const char *hostdomain = strchr(priv->hostname, '.');
-
-        if (hostdomain && !nm_utils_ipaddr_is_valid(AF_UNSPEC, priv->hostname)) {
-            hostdomain++;
-            if (domain_is_valid(hostdomain, TRUE))
-                add_string_item(rc.searches, hostdomain, TRUE);
-            else if (domain_is_valid(priv->hostname, TRUE))
-                add_string_item(rc.searches, priv->hostname, TRUE);
-        }
-    }
+    if (priv->hostdomain)
+        add_string_item(rc.searches, priv->hostdomain, TRUE);
 
     if (rc.has_trust_ad == NM_TERNARY_TRUE)
         g_ptr_array_add(rc.options, g_strdup(NM_SETTING_DNS_OPTION_TRUST_AD));
@@ -1695,7 +1680,7 @@ update_dns(NMDnsManager *self, gboolean no_caching, gboolean force_emit, GError
         nm_dns_plugin_update(priv->sd_resolve_plugin,
                              global_config,
                              _mgr_get_ip_data_lst_head(self),
-                             priv->hostname,
+                             priv->hostdomain,
                              NULL);
     }
 
@@ -1717,7 +1702,7 @@ update_dns(NMDnsManager *self, gboolean no_caching, gboolean force_emit, GError
         if (!nm_dns_plugin_update(plugin,
                                   global_config,
                                   _mgr_get_ip_data_lst_head(self),
-                                  priv->hostname,
+                                  priv->hostdomain,
                                   &plugin_error)) {
             _LOGW("update-dns: plugin %s update failed: %s", plugin_name, plugin_error->message);
 
@@ -2005,16 +1990,37 @@ done:
 void
 nm_dns_manager_set_hostname(NMDnsManager *self, const char *hostname, gboolean skip_update)
 {
-    NMDnsManagerPrivate *priv = NM_DNS_MANAGER_GET_PRIVATE(self);
+    NMDnsManagerPrivate *priv   = NM_DNS_MANAGER_GET_PRIVATE(self);
+    const char          *domain = NULL;
 
     /* Certain hostnames we don't want to include in resolv.conf 'searches' */
-    if (hostname && nm_utils_is_specific_hostname(hostname) && !strstr(hostname, ".in-addr.arpa")
-        && strchr(hostname, '.')) {
-        /* pass */
-    } else
-        hostname = NULL;
+    if (hostname && nm_utils_is_specific_hostname(hostname)
+        && !g_str_has_suffix(hostname, ".in-addr.arpa")
+        && !nm_utils_ipaddr_is_valid(AF_UNSPEC, hostname)) {
+        domain = strchr(hostname, '.');
+        if (domain) {
+            domain++;
+            /* If the hostname is a FQDN ("dcbw.example.com"), then add
+             * the domain part of it ("example.com") to the searches list,
+             * to ensure that we can still resolve its non-FQ form
+             * ("dcbw") too. (Also, if there are no other search domains
+             * specified, this makes a good default.) However, if the
+             * hostname is the top level of a domain (eg, "example.com"),
+             * then use the hostname itself as the search (since the user
+             * is unlikely to want "com" as a search domain).a
+             */
+            if (domain_is_valid(domain, TRUE)) {
+                /* pass */
+            } else if (domain_is_valid(hostname, TRUE)) {
+                domain = hostname;
+            }
+
+            if (!nm_sd_hostname_is_valid(domain, FALSE))
+                domain = NULL;
+        }
+    }
 
-    if (!nm_strdup_reset(&priv->hostname, hostname))
+    if (!nm_strdup_reset(&priv->hostdomain, domain))
         return;
 
     if (skip_update)
@@ -2659,7 +2665,7 @@ finalize(GObject *object)
     NMDnsManager        *self = NM_DNS_MANAGER(object);
     NMDnsManagerPrivate *priv = NM_DNS_MANAGER_GET_PRIVATE(self);
 
-    g_free(priv->hostname);
+    g_free(priv->hostdomain);
     g_free(priv->mode);
 
     G_OBJECT_CLASS(nm_dns_manager_parent_class)->finalize(object);
diff --git a/src/core/dns/nm-dns-plugin.c b/src/core/dns/nm-dns-plugin.c
index 2126da775f..847d783996 100644
--- a/src/core/dns/nm-dns-plugin.c
+++ b/src/core/dns/nm-dns-plugin.c
@@ -60,7 +60,7 @@ gboolean
 nm_dns_plugin_update(NMDnsPlugin             *self,
                      const NMGlobalDnsConfig *global_config,
                      const CList             *ip_config_lst_head,
-                     const char              *hostname,
+                     const char              *hostdomain,
                      GError                 **error)
 {
     g_return_val_if_fail(NM_DNS_PLUGIN_GET_CLASS(self)->update != NULL, FALSE);
@@ -68,7 +68,7 @@ nm_dns_plugin_update(NMDnsPlugin             *self,
     return NM_DNS_PLUGIN_GET_CLASS(self)->update(self,
                                                  global_config,
                                                  ip_config_lst_head,
-                                                 hostname,
+                                                 hostdomain,
                                                  error);
 }
 
diff --git a/src/core/dns/nm-dns-plugin.h b/src/core/dns/nm-dns-plugin.h
index bc854cceab..f9c424abfa 100644
--- a/src/core/dns/nm-dns-plugin.h
+++ b/src/core/dns/nm-dns-plugin.h
@@ -34,7 +34,7 @@ typedef struct {
     gboolean (*update)(NMDnsPlugin             *self,
                        const NMGlobalDnsConfig *global_config,
                        const CList             *ip_config_lst_head,
-                       const char              *hostname,
+                       const char              *hostdomain,
                        GError                 **error);
 
     void (*stop)(NMDnsPlugin *self);
diff --git a/src/core/dns/nm-dns-systemd-resolved.c b/src/core/dns/nm-dns-systemd-resolved.c
index a043e8555d..c4993884d2 100644
--- a/src/core/dns/nm-dns-systemd-resolved.c
+++ b/src/core/dns/nm-dns-systemd-resolved.c
@@ -551,7 +551,7 @@ static gboolean
 update(NMDnsPlugin             *plugin,
        const NMGlobalDnsConfig *global_config,
        const CList             *ip_data_lst_head,
-       const char              *hostname,
+       const char              *hostdomain,
        GError                 **error)
 {
     NMDnsSystemdResolved          *self            = NM_DNS_SYSTEMD_RESOLVED(plugin);
diff --git a/src/core/dns/nm-dns-unbound.c b/src/core/dns/nm-dns-unbound.c
index f5a533324f..8a75cf08f0 100644
--- a/src/core/dns/nm-dns-unbound.c
+++ b/src/core/dns/nm-dns-unbound.c
@@ -28,7 +28,7 @@ static gboolean
 update(NMDnsPlugin             *plugin,
        const NMGlobalDnsConfig *global_config,
        const CList             *ip_config_lst_head,
-       const char              *hostname,
+       const char              *hostdomain,
        GError                 **error)
 {
     char                 *argv[] = {DNSSEC_TRIGGER_PATH, "--async", "--update", NULL};
diff --git a/src/core/nm-policy.c b/src/core/nm-policy.c
index c6ecfa4bc7..2d47772d65 100644
--- a/src/core/nm-policy.c
+++ b/src/core/nm-policy.c
@@ -606,7 +606,7 @@ _set_hostname(NMPolicy *self, const char *new_hostname, const char *msg)
          */
         priv->updating_dns = TRUE;
         nm_dns_manager_set_hostname(priv->dns_manager,
-                                    priv->cur_hostname,
+                                    priv->cur_hostname_full,
                                     all_devices_not_active(self));
         priv->updating_dns = FALSE;
     }