dhcp: NTP servers should be requested by networkd but not implicitly by sd-dhcp

The library so far always requested the NTP servers. This might be
unnecessary in some uses, hence let's move the request into networkd
instead.

src/libsystemd-network/sd-dhcp-client.c

@@ -105,7 +105,6 @@ static const uint8_t default_req_opts[] = {
         DHCP_OPTION_HOST_NAME,
         DHCP_OPTION_DOMAIN_NAME,
         DHCP_OPTION_DOMAIN_NAME_SERVER,
-        DHCP_OPTION_NTP_SERVER,
 };
 
 static int client_receive_message_raw(sd_event_source *s, int fd,

src/libsystemd-network/test-dhcp-client.c

@@ -87,10 +87,7 @@ static void test_request_basic(sd_event *e)
         assert_se(sd_dhcp_client_set_request_option(client,
                                         DHCP_OPTION_DOMAIN_NAME) == -EEXIST);
         assert_se(sd_dhcp_client_set_request_option(client,
-                                        DHCP_OPTION_DOMAIN_NAME_SERVER)
-                        == -EEXIST);
-        assert_se(sd_dhcp_client_set_request_option(client,
-                                        DHCP_OPTION_NTP_SERVER) == -EEXIST);
+                                        DHCP_OPTION_DOMAIN_NAME_SERVER) == -EEXIST);
 
         assert_se(sd_dhcp_client_set_request_option(client,
                                         DHCP_OPTION_PAD) == -EINVAL);

src/network/networkd-dhcp4.c

@@ -624,7 +624,11 @@ int dhcp4_configure(Link *link) {
                         return r;
         }
 
-        /* Always acquire the timezone */
+        /* Always acquire the timezone and NTP*/
+        r = sd_dhcp_client_set_request_option(link->dhcp_client, DHCP_OPTION_NTP_SERVER);
+        if (r < 0)
+                return r;
+
         r = sd_dhcp_client_set_request_option(link->dhcp_client, DHCP_OPTION_NEW_TZDB_TIMEZONE);
         if (r < 0)
                 return r;