core: add nm_utils_shorten_hostname()

Add nm_utils_shorten_hostname() to shorten a hostname when too long.

3 files changed, 88 insertions, 1 deletions

diff --git a/src/nm-core-utils.c b/src/nm-core-utils.c
index 7adc011e30..0b62c86aff 100644
--- a/src/nm-core-utils.c
+++ b/src/nm-core-utils.c
@@ -34,6 +34,7 @@
 #include "nm-setting-ip6-config.h"
 #include "nm-setting-wireless.h"
 #include "nm-setting-wireless-security.h"
+#include "systemd/nm-sd-utils-shared.h"
 
 #ifdef __NM_SD_UTILS_H__
     #error \
@@ -5119,3 +5120,48 @@ NM_UTILS_LOOKUP_STR_DEFINE(nm_activation_type_to_string,
                            NM_UTILS_LOOKUP_STR_ITEM(NM_ACTIVATION_TYPE_MANAGED, "managed"),
                            NM_UTILS_LOOKUP_STR_ITEM(NM_ACTIVATION_TYPE_ASSUME, "assume"),
                            NM_UTILS_LOOKUP_STR_ITEM(NM_ACTIVATION_TYPE_EXTERNAL, "external"), );
+
+/*****************************************************************************/
+
+/**
+ * nm_utils_shorten_hostname:
+ * @hostname: the input hostname
+ * @shortened: (out) (transfer full): on return, the shortened hostname
+ *
+ * Checks whether the input hostname is valid. If not, tries to shorten it
+ * to HOST_NAME_MAX or to the first dot, whatever comes earlier.
+ * The new hostname is returned in @shortened.
+ *
+ * Returns: %TRUE if the input hostname was already valid or if was shortened
+ * successfully; %FALSE otherwise
+ */
+gboolean
+nm_utils_shorten_hostname(const char *hostname, char **shortened)
+{
+    gs_free char *s = NULL;
+    char *        dot;
+
+    nm_assert(hostname);
+    nm_assert(shortened);
+
+    if (nm_sd_hostname_is_valid(hostname, FALSE)) {
+        NM_SET_OUT(shortened, NULL);
+        return TRUE;
+    }
+
+    s   = g_strdup(hostname);
+    dot = strchr(s, '.');
+    if (dot)
+        *dot = 0;
+
+    if (strnlen(s, HOST_NAME_MAX + 1) > HOST_NAME_MAX)
+        s[HOST_NAME_MAX] = 0;
+
+    if (!nm_sd_hostname_is_valid(s, FALSE)) {
+        NM_SET_OUT(shortened, NULL);
+        return FALSE;
+    }
+
+    NM_SET_OUT(shortened, g_steal_pointer(&s));
+    return TRUE;
+}
diff --git a/src/nm-core-utils.h b/src/nm-core-utils.h
index ecbf1ebbff..ab6ff4a018 100644
--- a/src/nm-core-utils.h
+++ b/src/nm-core-utils.h
@@ -316,7 +316,7 @@ gboolean nm_utils_sysctl_ip_conf_is_path(int         addr_family,
                                          const char *ifname,
                                          const char *property);
 
-gboolean nm_utils_is_specific_hostname(const char *name);
+gboolean nm_utils_shorten_hostname(const char *hostname, char **shortened);
 
 struct _NMUuid;
 
diff --git a/src/tests/test-utils.c b/src/tests/test-utils.c
index 4635d98285..71fc4d9e48 100644
--- a/src/tests/test-utils.c
+++ b/src/tests/test-utils.c
@@ -216,6 +216,46 @@ test_hw_addr_gen_stable_eth(void)
                     "04:0D:CD:0C:9E:2C");
 }
 
+static void
+test_shorten_hostname(void)
+{
+    gboolean res;
+    char *   shortened = NULL;
+
+    res = nm_utils_shorten_hostname("name1", &shortened);
+    g_assert_cmpint(res, ==, TRUE);
+    g_assert_cmpstr(shortened, ==, NULL);
+    nm_clear_g_free(&shortened);
+
+    res = nm_utils_shorten_hostname("name1.example.com", &shortened);
+    g_assert_cmpint(res, ==, TRUE);
+    g_assert_cmpstr(shortened, ==, NULL);
+    nm_clear_g_free(&shortened);
+
+    res = nm_utils_shorten_hostname(
+        "name1.test-dhcp-this-one-here-is-a-very-very-long-domain.example.com",
+        &shortened);
+    g_assert_cmpint(res, ==, TRUE);
+    g_assert_cmpstr(shortened, ==, "name1");
+    nm_clear_g_free(&shortened);
+
+    res = nm_utils_shorten_hostname(
+        "test-dhcp-this-one-here-is-a-very-very-long-hostname-without-domainname",
+        &shortened);
+    g_assert_cmpint(res, ==, TRUE);
+    g_assert_cmpstr(shortened,
+                    ==,
+                    "test-dhcp-this-one-here-is-a-very-very-long-hostname-without-dom");
+    nm_clear_g_free(&shortened);
+
+    res = nm_utils_shorten_hostname(
+        ".test-dhcp-this-one-here-is-a-very-very-long-hostname.example.com",
+        &shortened);
+    g_assert_cmpint(res, ==, FALSE);
+    g_assert_cmpstr(shortened, ==, NULL);
+    nm_clear_g_free(&shortened);
+}
+
 /*****************************************************************************/
 
 NMTST_DEFINE();
@@ -227,6 +267,7 @@ main(int argc, char **argv)
 
     g_test_add_func("/utils/stable_privacy", test_stable_privacy);
     g_test_add_func("/utils/hw_addr_gen_stable_eth", test_hw_addr_gen_stable_eth);
+    g_test_add_func("/utils/shorten-hostname", test_shorten_hostname);
 
     return g_test_run();
 }