Build config validation into Config.get() accessor

lib/nntp/tiny/config.py

@@ -34,7 +34,7 @@ class ConfigFileException(ConfigException):
             ", ".join(self.paths)
         )
 
-class Config():
+class Config(configparser.ConfigParser):
     SEARCH_PATHS = [
         './server.conf',
         '/etc/nntp-tiny/server.conf'
@@ -48,6 +48,7 @@ class Config():
 
         return None
 
+    @staticmethod
     def load(path: Optional[str]=None):
         if path is None:
             path = Config.find()
@@ -55,7 +56,16 @@ class Config():
         if path is None:
             raise ConfigFileException(Config.SEARCH_PATHS)
 
-        parser = configparser.ConfigParser()
-        parser.read(path)
+        config = Config()
+        config.read(path)
 
-        return parser
+        return config
+
+    def get(self, section: str, option: str, *args, **kwargs):
+        if not self.has_section(section):
+            raise ConfigSectionException(section)
+
+        if not self.has_option(section, option):
+            raise ConfigValueException(section, option)
+
+        return super().get(section, option, *args, **kwargs)

lib/nntp/tiny/daemon.py

@@ -2,20 +2,12 @@ import os
 import signal
 import configparser
 
-from nntp.tiny.config import (ConfigSectionException,
-                              ConfigValueException)
+from nntp.tiny.config import Config
 
 class Daemon():
-    def init(config: configparser.ConfigParser):
-        if not config.has_section('daemon'):
-            raise ConfigSectionException('daemon')
-
-        if not config.has_option('daemon', 'pidfile'):
-            raise ConfigValueException('daemon', 'pidfile')
-
+    def init(config: Config):
         pidfile = config.get('daemon', 'pidfile')
-
-        pid = os.fork()
+        pid     = os.fork()
 
         if pid > 0:
             exit(0)

lib/nntp/tiny/server.py

@@ -5,10 +5,7 @@ import socket
 import selectors
 import ssl
 
-from configparser import ConfigParser
-
-from nntp.tiny.config    import (
-    ConfigException, ConfigSectionException, ConfigValueException)
+from nntp.tiny.config    import Config, ConfigException
 from nntp.tiny.db        import Database
 from nntp.tiny.newsgroup import Newsgroup
 from nntp.tiny.session   import Session
@@ -19,36 +16,21 @@ class ServerCapability(enum.Flag):
     POST = enum.auto()
 
 class Server():
-    def __init__(self, config: ConfigParser):
+    def __init__(self, config: Config):
         self.config       = config
         self.capabilities = ServerCapability.NONE
         self.newsgroups   = dict()
         self.sslctx       = None
 
         if config['listen'].get('tls', 'no') == 'yes':
-            if not config.has_section('tls'):
-                raise ConfigSectionException('tls')
-
-            if not config.has_option('tls', 'cert'):
-                raise ConfigValueException('tls', 'cert')
-
-            if not config.has_option('tls', 'key'):
-                raise ConfigValueException('tls', 'key')
-
             self.sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
-            self.sslctx.load_cert_chain(config['tls']['cert'],
-                                        config['tls']['key'])
+            self.sslctx.load_cert_chain(config.get('tls', 'cert'),
+                                        config.get('tls', 'key'))
 
         self._init_newsgroups()
 
     def connect_to_db(self):
-        if not self.config.has_section('database'):
-            raise ConfigSectionException('database')
-
-        if not self.config.has_option('database', 'path'):
-            raise ConfigValueException('database', 'path')
-
-        return Database.connect(self.config['database']['path'])
+        return Database.connect(self.config.get('database', 'path'))
 
     def _init_newsgroups(self):
         db = self.connect_to_db()
@@ -108,14 +90,8 @@ class Server():
         return True
 
     def run(self):
-        if not self.config.has_section('listen'):
-            raise ConfigSectionException('listen')
-
-        if not self.config.has_option('listen', 'host'):
-            raise ConfigValueException('listen', 'host')
-
-        hosts = re.split(r'\s*,\s*', self.config['listen']['host'])
-        port  = int(self.config['listen']['port'])
+        hosts = re.split(r'\s*,\s*', self.config.get('listen', 'host'))
+        port  = int(self.config.get('listen', 'port'))
 
         listeners = list()