From 7500f59ce0dbd8d376c008001dd638ad2844ab2b Mon Sep 17 00:00:00 2001
From: Camil Staps
Date: Mon, 23 May 2016 22:01:31 +0200
Subject: Framework 2

---
 project2/proj2_s4498062/dns/cache.py | 89 ++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 project2/proj2_s4498062/dns/cache.py

(limited to 'project2/proj2_s4498062/dns/cache.py')

diff --git a/project2/proj2_s4498062/dns/cache.py b/project2/proj2_s4498062/dns/cache.py
new file mode 100644
index 0000000..e148d3a
--- /dev/null
+++ b/project2/proj2_s4498062/dns/cache.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python2
+
+"""A cache for resource records
+
+This module contains a class which implements a cache for DNS resource records,
+you still have to do most of the implementation. The module also provides a
+class and a function for converting ResourceRecords from and to JSON strings.
+It is highly recommended to use these.
+"""
+
+import json
+
+from dns.resource import ResourceRecord, RecordData
+from dns.types import Type
+from dns.classes import Class
+
+
+class ResourceEncoder(json.JSONEncoder):
+    """ Conver ResourceRecord to JSON
+
+    Usage:
+        string = json.dumps(records, cls=ResourceEncoder, indent=4)
+    """
+    def default(self, obj):
+        if isinstance(obj, ResourceRecord):
+            return {
+                "name": obj.name,
+                "type": Type.to_string(obj.type_),
+                "class": Class.to_string(obj.class_),
+                "ttl": obj.ttl,
+                "rdata": obj.rdata.data
+            }
+        return json.JSONEncoder.default(self, obj)
+
+
+def resource_from_json(dct):
+    """ Convert JSON object to ResourceRecord
+
+    Usage:
+        records = json.loads(string, object_hook=resource_from_json)
+    """
+    name = dct["name"]
+    type_ = Type.from_string(dct["type"])
+    class_ = Class.from_string(dct["class"])
+    ttl = dct["ttl"]
+    rdata = RecordData.create(type_, dct["rdata"])
+    return ResourceRecord(name, type_, class_, ttl, rdata)
+
+
+class RecordCache(object):
+    """ Cache for ResourceRecords """
+
+    def __init__(self, ttl):
+        """ Initialize the RecordCache
+
+        Args:
+            ttl (int): TTL of cached entries (if > 0)
+        """
+        self.records = []
+        self.ttl = ttl
+
+    def lookup(self, dname, type_, class_):
+        """ Lookup resource records in cache
+
+        Lookup for the resource records for a domain name with a specific type
+        and class.
+
+        Args:
+            dname (str): domain name
+            type_ (Type): type
+            class_ (Class): class
+        """
+        pass
+
+    def add_record(self, record):
+        """ Add a new Record to the cache
+
+        Args:
+            record (ResourceRecord): the record added to the cache
+        """
+        pass
+
+    def read_cache_file(self):
+        """ Read the cache file from disk """
+        pass
+
+    def write_cache_file(self):
+        """ Write the cache file to disk """
+        pass
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