T560: refactor the pdns script and switch to jinja2.

1 files changed, 108 insertions, 102 deletions

diff --git a/src/conf-mode/vyos-config-dns-forwarding.py b/src/conf-mode/vyos-config-dns-forwarding.py
index 3b5142ea4..1aa42e1c1 100755
--- a/src/conf-mode/vyos-config-dns-forwarding.py
+++ b/src/conf-mode/vyos-config-dns-forwarding.py
@@ -19,13 +19,61 @@
 import sys
 import os
 import time
+
 import netifaces
+import jinja2
 
 from vyos.config import Config
 from vyos.util import ConfigError
 
 config_file = r'/etc/powerdns/recursor.conf'
 
+# XXX: pdns recursor doesn't like whitespace near entry separators,
+# especially in the semicolon-separated lists of name servers.
+# Please be careful if you edit the template.
+config_tmpl = """
+
+### Autogenerated by vyos-config-dns-forwarding.py ###
+
+# Non-configurable defaults
+daemon=yes
+threads=1
+allow-from=0.0.0.0/0
+log-common-errors=yes
+
+# cache-size
+max-cache-entries={{ cache_size }}
+
+# ignore-hosts-file
+export-etc-hosts={{ export_hosts_file }}
+
+# listen-on
+local-address= {{ listen_on | join(',') }}
+
+# domain ... server ...
+{% if domains -%}
+
+{% for d in domains -%}
+forward-zones = {{ d.name }} = {{ d.servers | join(";") }}
+{% endfor -%}
+
+{% endif %}
+
+# name-server
+forward-zones-recurse=.=  {{ name_servers | join(';') }}
+
+"""
+
+default_config_data = {
+    'cache_size' : 10000,
+    'export_hosts_file': 'yes',
+    'listen_on': [],
+    'interfaces': [],
+    'name_servers': [],
+    'domains': []
+}
+
+
 # borrowed from: https://github.com/donjajo/py-world/blob/master/resolvconfReader.py, THX!
 def get_resolvers(file):
     resolvers = []
@@ -41,99 +89,54 @@ def get_resolvers(file):
         return []
 
 def get_config():
-    dns = {}
+    dns = default_config_data
     conf = Config()
-    conf.set_level('service dns forwarding')
-    if not conf.exists(''):
-        return dns
+    if not conf.exists('service dns forwarding'):
+        return None
+    else:
+        conf.set_level('service dns forwarding')
 
     if conf.exists('cache-size'):
-        cache = conf.return_value('cache-size')
-        dns.setdefault('cache-size', cache)
-
-    if conf.exists('dhcp'):
-        dns.setdefault('dhcp', [])
-        interfaces = []
-        interfaces = conf.return_values('dhcp')
-        for interface in interfaces:
-            resolvers = get_resolvers("/etc/resolv.conf.dhclient-new-{0}".format(interface))
-            if len(resolvers) > 0:
-                dhcp = {
-                    "interface": interface,
-                    "resolvers": resolvers
-                }
-                dns['dhcp'].append(dhcp)
+        cache_size = conf.return_value('cache-size')
+        dns['cache_size'] = cache_size
 
     if conf.exists('domain'):
-        dns.setdefault('domain', [])
         for node in conf.list_nodes('domain'):
             server = conf.return_values("domain {0} server".format(node))
             domain = {
                 "name": node,
-                "server": server
+                "servers": server
             }
-            dns['domain'].append(domain)
+            dns['domains'].append(domain)
 
     if conf.exists('ignore-hosts-file'):
-        dns.setdefault('ignore-hosts-file', True)
-
-    if conf.exists('listen-on'):
-        interfaces = []
-        interfaces = conf.return_values('listen-on')
-        dns.setdefault('listen-on', interfaces)
+        dns.setdefault('export_hosts_file', "no")
 
     if conf.exists('name-server'):
-        nameservers = []
-        nameservers = conf.return_values('name-server')
-        dns.setdefault('name-server', nameservers)
+        name_servers = conf.return_values('name-server')
+        dns.setdefault('name_servers', name_servers)
 
     if conf.exists('system'):
         conf.set_level('system')
-        nameservers = []
-        nameservers = conf.return_values('name-server')
-        if len(nameservers) == 0:
+        system_name_servers = []
+        system_name_servers = conf.return_values('name-server')
+        if not system_name_servers:
             print("DNS forwarding warning: No name-servers set under 'system name-server'\n")
         else:
-            dns.setdefault('system-name-server', nameservers)
+            dns['name_servers'] = dns['name_servers'] + system_name_servers
+        conf.set_level('service dns forwarding')
 
-    return dns
-
-def verify(dns):
-    if len(dns) > 0:
-        if 'listen-on' not in dns.keys():
-            raise ConfigError('Error: DNS forwarding requires a configured listen interface!')
-
-        for interface in dns['listen-on']:
-            try:
-                netifaces.ifaddresses(interface)[netifaces.AF_INET]
-            except KeyError as e:
-                raise ConfigError('Error: Interface {0} has no IP address assigned'.format(interface))
-
-        if 'domain' in dns.keys():
-            for domain in dns['domain']:
-                if len(domain['server']) == 0:
-                    raise ConfigError('Error: No server configured for domain {0}'.format(domain['name']))
-
-    return None
-
-def generate(dns):
-    config_header = '### Autogenerated by vyos-config-dns-forwarding.py on {tm} ###\n'.format(tm=time.strftime("%a, %d %b %Y %H:%M:%S", time.localtime()))
+    ## Hacks and tricks
 
-    fwds = []
-    fwds_src = []
-
-    # write new configuration file
-    f = open(config_file, 'w')
-    f.write(config_header)
-    f.write('daemon=yes\n')
-    f.write('threads=1\n')
-    f.write('allow-from=0.0.0.0/0\n')
-    f.write('log-common-errors=yes\n')
+    # The old VyOS syntax that comes from dnsmasq was "listen-on $interface".
+    # pdns wants addresses instead, so we emulate it by looking up all addresses
+    # of a given interface and writing them to the config
+    if conf.exists('listen-on'):
+        interfaces = conf.return_values('listen-on')
 
-    if 'listen-on' in dns.keys():
         listen4 = []
         listen6 = []
-        for interface in dns['listen-on']:
+        for interface in interfaces:
             addrs = netifaces.ifaddresses(interface)
             for ip4 in addrs[netifaces.AF_INET]:
                 listen4.append(ip4['addr'])
@@ -141,52 +144,55 @@ def generate(dns):
             for ip6 in addrs[netifaces.AF_INET6]:
                 listen6.append(ip6['addr'])
 
-        # build local-address string, example:
-        # local-address=172.16.37.240, 127.0.0.1, 172.16.254.35, 172.16.77.1, 2001:DB8::1:25, ::1
-        f.write('local-address=' + ', '.join(listen4) + ', ' + ', '.join(listen6) + '\n')
+        dns['listen_on'] = listen4 + listen6
 
-    if 'cache-size' in dns.keys():
-        f.write("max-cache-entries={0}\n".format(dns['cache-size']))
+        # Save interfaces in the dict for the reference
+        dns['interfaces'] = interfaces
 
-    if 'dhcp' in dns.keys():
-        for dhcp in dns['dhcp']:
-            fwds_src.append('DHCP: {0} ({1})'.format(dhcp['interface'], ', '.join(str(ns) for ns in dhcp['resolvers'])))
-            fwds.append(', '.join(str(ns) for ns in dhcp['resolvers']))
+    # Add name servers received from DHCP
+    if conf.exists('dhcp'):
+        interfaces = []
+        interfaces = conf.return_values('dhcp')
+        for interface in interfaces:
+            dhcp_resolvers = get_resolvers("/etc/resolv.conf.dhclient-new-{0}".format(interface))
+            if dhcp_resolvers:
+                dns['name_servers'] = dns['name_servers'] + dhcp_resolvers
 
-    if 'domain' in dns.keys():
-        zones = []
-        for domain in dns['domain']:
-            zones.append('{0}={1}'.format(domain['name'], ';'.join(str(ns) for ns in domain['server'])))
-        f.write('forward-zones=' + ', '.join(zones) + '\n')
+    return dns
 
-    if 'ignore-hosts-file' in dns.keys():
-        f.write("export-etc-hosts=no\n")
-    else:
-        f.write("export-etc-hosts=yes\n")
+def verify(dns):
+    if not dns['interfaces']:
+        raise ConfigError('Error: DNS forwarding requires a configured listen interface!')
 
-    if 'name-server' in dns.keys():
-        fwds_src.append('statically configured: {0}'.format(', '.join(str(ns) for ns in dns['name-server'])))
-        fwds.append(', '.join(str(ns) for ns in dns['name-server']))
+    for interface in dns['interfaces']:
+        try:
+            netifaces.ifaddresses(interface)[netifaces.AF_INET]
+        except KeyError as e:
+            raise ConfigError('Error: Interface {0} has no IP address assigned'.format(interface))
 
-    if 'system-name-server' in dns.keys():
-        fwds_src.append('system: {0}'.format(', '.join(str(ns) for ns in dns['system-name-server'])))
-        fwds.append(', '.join(str(ns) for ns in dns['system-name-server']))
+    if dns['domains']:
+        for domain in dns['domains']:
+            if not domain['servers']:
+                raise ConfigError('Error: No server configured for domain {0}'.format(domain['name']))
 
-    if len(fwds) > 0:
-        f.write('\n')
-        f.write('# ' + '\n# '.join(fwds_src) + '\n')
-        f.write('forward-zones-recurse=.=' + '; '.join(fwds) + '\n')
+    return None
+
+def generate(dns):
+    tmpl = jinja2.Template(config_tmpl)
 
-    f.close()
+    config_text = tmpl.render(dns)
+    with open(config_file, 'w') as f:
+        f.write(config_text)
     return None
 
 def apply(dns):
-    if len(dns) == 0:
-        cmd = "sudo systemctl stop pdns-recursor"
+    if dns:
+        os.system("systemctl restart pdns-recursor")
     else:
-        cmd = "sudo systemctl restart pdns-recursor"
+        # DNS forwarding is removed in the commit
+        os.system("systemctl stop pdns-recursor")
+        os.unlink(config_file)
 
-    os.system(cmd)
     return None
 
 if __name__ == '__main__':