name-server: T3804: merge "system name-servers-dhcp" into "system name-server"

We have "set system name-server <ipv4|ipv6>" to specify a name-server IP
address we wan't to use. We also have "set system name-servers-dhcp <interface>"
which does the same, but the name-server in question is retrieved via DHCP.

Both CLI nodes are combined under "set system name-server <ipv4|ipv6|interface>"
to keep things as they are in real life - we need a name-server.

(cherry picked from commit 2ecf7a9f9cbe9359457bd23b4a0c45f3763123c7)

3 files changed, 88 insertions, 34 deletions

diff --git a/interface-definitions/dns-domain-name.xml.in b/interface-definitions/dns-domain-name.xml.in
index ff632e1d1..2b1644609 100644
--- a/interface-definitions/dns-domain-name.xml.in
+++ b/interface-definitions/dns-domain-name.xml.in
@@ -1,37 +1,34 @@
 <?xml version="1.0"?>
-<!-- host-name configuration -->
 <interfaceDefinition>
   <node name="system">
     <children>
       <leafNode name="name-server" owner="${vyos_conf_scripts_dir}/host_name.py">
         <properties>
-          <help>Domain Name Servers (DNS) used by the system (resolv.conf)</help>
+          <help>System Domain Name Servers (DNS)</help>
           <priority>400</priority>
+          <completionHelp>
+            <script>${vyos_completion_dir}/list_interfaces.py</script>
+          </completionHelp>
           <valueHelp>
             <format>ipv4</format>
-            <description>Domain Name Server (DNS) address</description>
+            <description>Domain Name Server IPv4 address</description>
           </valueHelp>
           <valueHelp>
             <format>ipv6</format>
-            <description>Domain Name Server (DNS) address</description>
+            <description>Domain Name Server IPv6 address</description>
+          </valueHelp>
+          <valueHelp>
+            <format>txt</format>
+            <description>Use Domain Name Server from DHCP interface</description>
           </valueHelp>
           <multi/>
           <constraint>
             <validator name="ipv4-address"/>
             <validator name="ipv6-address"/>
+            <validator name="interface-name"/>
           </constraint>
         </properties>
       </leafNode>
-      <leafNode name="name-servers-dhcp" owner="${vyos_conf_scripts_dir}/host_name.py">
-        <properties>
-          <help>Interfaces whose DHCP client nameservers will be used by the system (resolv.conf)</help>
-          <priority>400</priority>
-          <completionHelp>
-            <script>${vyos_completion_dir}/list_interfaces.py</script>
-          </completionHelp>
-          <multi/>
-        </properties>
-      </leafNode>
       <leafNode name="host-name" owner="${vyos_conf_scripts_dir}/host_name.py">
         <properties>
           <help>System host name (default: vyos)</help>
diff --git a/src/conf_mode/host_name.py b/src/conf_mode/host_name.py
index f4c75c257..a7135911d 100755
--- a/src/conf_mode/host_name.py
+++ b/src/conf_mode/host_name.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2018-2020 VyOS maintainers and contributors
+# Copyright (C) 2018-2021 VyOS maintainers and contributors
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 or later as
@@ -14,10 +14,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-"""
-conf-mode script for 'system host-name' and 'system domain-name'.
-"""
-
 import re
 import sys
 import copy
@@ -25,10 +21,13 @@ import copy
 import vyos.util
 import vyos.hostsd_client
 
-from vyos.config import Config
 from vyos import ConfigError
-from vyos.util import cmd, call, process_named_running
-
+from vyos.config import Config
+from vyos.ifconfig import Section
+from vyos.template import is_ip
+from vyos.util import cmd
+from vyos.util import call
+from vyos.util import process_named_running
 from vyos import airbag
 airbag.enable()
 
@@ -37,7 +36,7 @@ default_config_data = {
     'domain_name': '',
     'domain_search': [],
     'nameserver': [],
-    'nameservers_dhcp_interfaces': [],
+    'nameservers_dhcp_interfaces': {},
     'static_host_mapping': {}
 }
 
@@ -51,29 +50,37 @@ def get_config(config=None):
 
     hosts = copy.deepcopy(default_config_data)
 
-    hosts['hostname'] = conf.return_value("system host-name")
+    hosts['hostname'] = conf.return_value(['system', 'host-name'])
 
     # This may happen if the config is not loaded yet,
     # e.g. if run by cloud-init
     if not hosts['hostname']:
         hosts['hostname'] = default_config_data['hostname']
 
-    if conf.exists("system domain-name"):
-        hosts['domain_name'] = conf.return_value("system domain-name")
+    if conf.exists(['system', 'domain-name']):
+        hosts['domain_name'] = conf.return_value(['system', 'domain-name'])
         hosts['domain_search'].append(hosts['domain_name'])
 
-    for search in conf.return_values("system domain-search domain"):
+    for search in conf.return_values(['system', 'domain-search', 'domain']):
         hosts['domain_search'].append(search)
 
-    hosts['nameserver'] = conf.return_values("system name-server")
+    if conf.exists(['system', 'name-server']):
+        for ns in conf.return_values(['system', 'name-server']):
+            if is_ip(ns):
+                hosts['nameserver'].append(ns)
+            else:
+                tmp = ''
+                if_type = Section.section(ns)
+                if conf.exists(['interfaces', if_type, ns, 'address']):
+                    tmp = conf.return_values(['interfaces', if_type, ns, 'address'])
 
-    hosts['nameservers_dhcp_interfaces'] = conf.return_values("system name-servers-dhcp")
+                hosts['nameservers_dhcp_interfaces'].update({ ns : tmp })
 
     # system static-host-mapping
-    for hn in conf.list_nodes('system static-host-mapping host-name'):
+    for hn in conf.list_nodes(['system', 'static-host-mapping', 'host-name']):
         hosts['static_host_mapping'][hn] = {}
-        hosts['static_host_mapping'][hn]['address'] = conf.return_value(f'system static-host-mapping host-name {hn} inet')
-        hosts['static_host_mapping'][hn]['aliases'] = conf.return_values(f'system static-host-mapping host-name {hn} alias')
+        hosts['static_host_mapping'][hn]['address'] = conf.return_value(['system', 'static-host-mapping', 'host-name', hn, 'inet'])
+        hosts['static_host_mapping'][hn]['aliases'] = conf.return_values(['system', 'static-host-mapping', 'host-name', hn, 'alias'])
 
     return hosts
 
@@ -103,8 +110,10 @@ def verify(hosts):
             if not hostname_regex.match(a) and len(a) != 0:
                 raise ConfigError(f'Invalid alias "{a}" in static-host-mapping "{host}"')
 
-    # TODO: add warnings for nameservers_dhcp_interfaces if interface doesn't
-    # exist or doesn't have address dhcp(v6)
+    for interface, interface_config in hosts['nameservers_dhcp_interfaces'].items():
+        # Warnin user if interface does not have DHCP or DHCPv6 configured
+        if not set(interface_config).intersection(['dhcp', 'dhcpv6']):
+            print(f'WARNING: "{interface}" is not a DHCP interface but uses DHCP name-server option!')
 
     return None
 
diff --git a/src/migration-scripts/system/20-to-21 b/src/migration-scripts/system/20-to-21
new file mode 100755
index 000000000..1728995de
--- /dev/null
+++ b/src/migration-scripts/system/20-to-21
@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# T3795: merge "system name-servers-dhcp" into "system name-server"
+
+import os
+
+from sys import argv
+from vyos.configtree import ConfigTree
+
+if (len(argv) < 1):
+    print("Must specify file name!")
+    exit(1)
+
+file_name = argv[1]
+with open(file_name, 'r') as f:
+    config_file = f.read()
+
+base = ['system', 'name-servers-dhcp']
+config = ConfigTree(config_file)
+if not config.exists(base):
+    # Nothing to do
+    exit(0)
+
+for interface in config.return_values(base):
+    config.set(['system', 'name-server'], value=interface, replace=False)
+
+config.delete(base)
+
+try:
+    with open(file_name, 'w') as f:
+        f.write(config.to_string())
+except OSError as e:
+    print("Failed to save the modified config: {}".format(e))
+    exit(1)