always try to find key and certificate in config

opennsa/config.py

@@ -315,6 +315,16 @@ class Config(object):
         except configparser.NoOptionError:
             vc[BASE_URL] = None
 
+        try:
+            vc[KEY] = cfg.get(BLOCK_SERVICE, KEY)
+        except configparser.NoOptionError:
+            vc[KEY] = None
+
+        try:
+            vc[CERTIFICATE] = cfg.get(BLOCK_SERVICE, CERTIFICATE)
+        except configparser.NoOptionError:
+            vc[CERTIFICATE] = None
+
         try:
             policies = cfg.get(BLOCK_SERVICE, POLICY).split(',')
             for policy in policies:
@@ -356,18 +366,19 @@ class Config(object):
         # tls
         if vc[TLS]:
             try:
-                hostkey = cfg.get(BLOCK_SERVICE, KEY)
-                hostcert = cfg.get(BLOCK_SERVICE, CERTIFICATE)
-
-                if not os.path.exists(hostkey):
+                if not vc[KEY]:
                     raise ConfigurationError(
-                        'Specified hostkey does not exist (%s)' % hostkey)
-                if not os.path.exists(hostcert):
+                        'must specify a key when TLS is enabled')
+                elif not os.path.exists(vc[KEY]):
                     raise ConfigurationError(
-                        'Specified hostcert does not exist (%s)' % hostcert)
+                        'Specified key does not exist (%s)' % vc[KEY])
 
-                vc[KEY] = hostkey
-                vc[CERTIFICATE] = hostcert
+                if not vc[CERTIFICATE]:
+                    raise ConfigurationError(
+                        'must specify a certificate when TLS is enabled')
+                elif not os.path.exists(vc[CERTIFICATE]):
+                    raise ConfigurationError(
+                        'Specified certificate does not exist (%s)' % vc[CERTIFICATE])
 
                 try:
                     allowed_hosts_cfg = cfg.get(BLOCK_SERVICE, ALLOWED_HOSTS)