core,glib-aux: move nm_hostname_manager_validate_hostname() to shared-utils

This function is badly named, because it has no NMHostnameManager self
argument. It's just a simple function that entirely operates on a string
argument.

Move it away from "nm-hostname-manager.h" to "libnm-glib-aux/nm-shared-utils.h".

Hostname handling is complicated enough. Simple string validation
functions should not obscure the view on the complicated parts.

src/core/devices/nm-device.c

@@ -17653,7 +17653,7 @@ hostname_dns_lookup_callback(GObject *source, GAsyncResult *result, gpointer use
         gboolean valid;
 
         resolver->hostname = g_steal_pointer(&output);
-        valid              = nm_hostname_manager_validate_hostname(resolver->hostname);
+        valid              = nm_utils_validate_hostname(resolver->hostname);
 
         _LOGD(LOGD_DNS,
               "hostname-from-dns: lookup done for %s, result %s%s%s%s",

src/core/nm-hostname-manager.c

@@ -389,33 +389,6 @@ nm_hostname_manager_write_hostname(NMHostnameManager *self, const char *hostname
     return TRUE;
 }
 
-gboolean
-nm_hostname_manager_validate_hostname(const char *hostname)
-{
-    const char *p;
-    gboolean    dot = TRUE;
-
-    if (!hostname || !hostname[0])
-        return FALSE;
-
-    for (p = hostname; *p; p++) {
-        if (*p == '.') {
-            if (dot)
-                return FALSE;
-            dot = TRUE;
-        } else {
-            if (!g_ascii_isalnum(*p) && (*p != '-') && (*p != '_'))
-                return FALSE;
-            dot = FALSE;
-        }
-    }
-
-    if (dot)
-        return FALSE;
-
-    return (p - hostname <= HOST_NAME_MAX);
-}
-
 static void
 hostname_file_changed_cb(GFileMonitor *    monitor,
                          GFile *           file,

src/core/nm-hostname-manager.h

@@ -45,6 +45,4 @@ void nm_hostname_manager_set_transient_hostname(NMHostnameManager *            s
 
 gboolean nm_hostname_manager_get_transient_hostname(NMHostnameManager *self, char **hostname);
 
-gboolean nm_hostname_manager_validate_hostname(const char *hostname);
-
 #endif /* __NM_HOSTNAME_MANAGER_H__ */

src/core/settings/nm-settings.c

@@ -3441,7 +3441,7 @@ impl_settings_save_hostname(NMDBusObject *                     obj,
     g_variant_get(parameters, "(&s)", &hostname);
 
     /* Minimal validation of the hostname */
-    if (!nm_hostname_manager_validate_hostname(hostname)) {
+    if (!nm_utils_validate_hostname(hostname)) {
         error_code   = NM_SETTINGS_ERROR_INVALID_HOSTNAME;
         error_reason = "The hostname was too long or contained invalid characters";
         goto err;

src/libnm-glib-aux/nm-shared-utils.c

@@ -6356,3 +6356,32 @@ nm_utils_get_process_exit_status_desc(int status)
     else
         return g_strdup_printf("exited with unknown status 0x%x", status);
 }
+
+/*****************************************************************************/
+
+gboolean
+nm_utils_validate_hostname(const char *hostname)
+{
+    const char *p;
+    gboolean    dot = TRUE;
+
+    if (!hostname || !hostname[0])
+        return FALSE;
+
+    for (p = hostname; *p; p++) {
+        if (*p == '.') {
+            if (dot)
+                return FALSE;
+            dot = TRUE;
+        } else {
+            if (!g_ascii_isalnum(*p) && (*p != '-') && (*p != '_'))
+                return FALSE;
+            dot = FALSE;
+        }
+    }
+
+    if (dot)
+        return FALSE;
+
+    return (p - hostname <= HOST_NAME_MAX);
+}

src/libnm-glib-aux/nm-shared-utils.h

@@ -2992,4 +2992,6 @@ void nm_crypto_md5_hash(const guint8 *salt,
 
 char *nm_utils_get_process_exit_status_desc(int status);
 
+gboolean nm_utils_validate_hostname(const char *hostname);
+
 #endif /* __NM_SHARED_UTILS_H__ */