diff options
Diffstat (limited to 'project2/proj2_s4498062/dns/resource.py')
| -rw-r--r-- | project2/proj2_s4498062/dns/resource.py | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/project2/proj2_s4498062/dns/resource.py b/project2/proj2_s4498062/dns/resource.py new file mode 100644 index 0000000..57fc53e --- /dev/null +++ b/project2/proj2_s4498062/dns/resource.py @@ -0,0 +1,236 @@ +#!/usr/bin/env python2
+
+""" A DNS resource record
+
+This class contains classes for DNS resource records and record data. This
+module is fully implemented. You will have this module in the implementation
+of your resolver and server.
+"""
+
+import socket
+import struct
+
+from dns.classes import Class
+from dns.types import Type
+
+
+class ResourceRecord(object):
+ """ DNS resource record """
+ def __init__(self, name, type_, class_, ttl, rdata):
+ """ Create a new resource record
+
+ Args:
+ name (str): domain name
+ type_ (Type): the type
+ class_ (Class): the class
+ rdata (RecordData): the record data
+ """
+ self.name = name
+ self.type_ = type_
+ self.class_ = class_
+ self.ttl = ttl
+ self.rdata = rdata
+
+ def to_bytes(self, offset, composer):
+ """ Convert ResourceRecord to bytes """
+ name = composer.to_bytes(offset, [self.name])
+ offset += len(name)
+ rdata = self.rdata.to_bytes(offset, composer)
+ return (name +
+ struct.pack("!HHIH",
+ self.type_,
+ self.class_,
+ self.ttl,
+ len(rdata)) +
+ rdata)
+
+ @classmethod
+ def from_bytes(cls, packet, offset, parser):
+ """ Convert ResourceRecord from bytes """
+ names, offset = parser.from_bytes(packet, offset, 1)
+ name = names[0]
+ type_, class_, ttl, rdlength = struct.unpack_from("!HHIH", packet, offset)
+ offset += 10
+ rdata = RecordData.from_bytes(type_, packet, offset, rdlength, parser)
+ offset += rdlength
+ return cls(name, type_, class_, ttl, rdata), offset
+
+
+class RecordData(object):
+ """ Record Data """
+
+ def __init__(self, data):
+ """ Initialize the record data
+
+ Args:
+ data (str): data
+ """
+ self.data = data
+
+ @staticmethod
+ def create(type_, data):
+ """ Create a RecordData object from bytes
+
+ Args:
+ type_ (Type): type
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ classdict = {
+ Type.A: ARecordData,
+ Type.CNAME: CNAMERecordData,
+ Type.NS: NSRecordData,
+ Type.AAAA: AAAARecordData
+ }
+ if type_ in classdict:
+ return classdict[type_](data)
+ else:
+ return GenericRecordData(data)
+
+ @staticmethod
+ def from_bytes(type_, packet, offset, rdlength, parser):
+ """ Create a RecordData object from bytes
+
+ Args:
+ type_ (Type): type
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ classdict = {
+ Type.A: ARecordData,
+ Type.CNAME: CNAMERecordData,
+ Type.NS: NSRecordData,
+ Type.AAAA: AAAARecordData
+ }
+ if type_ in classdict:
+ return classdict[type_].from_bytes(
+ packet, offset, rdlength, parser)
+ else:
+ return GenericRecordData.from_bytes(
+ packet, offset, rdlength, parser)
+
+
+class ARecordData(RecordData):
+ def to_bytes(self, offset, composer):
+ """ Convert to bytes
+
+ Args:
+ offset (int): offset in message
+ composer (Composer): domain name composer
+ """
+ return socket.inet_aton(self.data)
+
+ @classmethod
+ def from_bytes(cls, packet, offset, rdlength, parser):
+ """ Create a RecordData object from bytes
+
+ Args:
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ data = socket.inet_ntoa(packet[offset:offset+4])
+ return cls(data)
+
+
+class CNAMERecordData(RecordData):
+ def to_bytes(self, offset, composer):
+ """ Convert to bytes
+
+ Args:
+ offset (int): offset in message
+ composer (Composer): domain name composer
+ """
+ return composer.to_bytes(offset, [self.data])
+
+ @classmethod
+ def from_bytes(cls, packet, offset, rdlength, parser):
+ """ Create a RecordData object from bytes
+
+ Args:
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ names, offset = parser.from_bytes(packet, offset, 1)
+ data = names[0]
+ return cls(data)
+
+
+class NSRecordData(RecordData):
+ def to_bytes(self, offset, composer):
+ """ Convert to bytes
+
+ Args:
+ offset (int): offset in message
+ composer (Composer): domain name composer
+ """
+ return composer.to_bytes(offset, [self.data])
+
+ @classmethod
+ def from_bytes(cls, packet, offset, rdlength, parser):
+ """ Create a RecordData object from bytes
+
+ Args:
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ names, offset = parser.from_bytes(packet, offset, 1)
+ data = names[0]
+ return cls(data)
+
+
+class AAAARecordData(RecordData):
+ def to_bytes(self, offset, composer):
+ """ Convert to bytes
+
+ Args:
+ offset (int): offset in message
+ composer (Composer): domain name composer
+ """
+ return socket.inet_pton(socket.AF_INET6, self.data)
+
+ @classmethod
+ def from_bytes(packet, offset, rdlength, parser):
+ """ Create a RecordData object from bytes
+
+ Args:
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ data = socket.inet_ntop(socket.AF_INET6, packet[offset:offset+16])
+ return cls(data)
+
+
+class GenericRecordData(RecordData):
+ def to_bytes(self, offset, composer):
+ """ Convert to bytes
+
+ Args:
+ offset (int): offset in message
+ composer (Composer): domain name composer
+ """
+ return self.data
+
+ @classmethod
+ def from_bytes(packet, offset, rdlength, parser):
+ """ Create a RecordData object from bytes
+
+ Args:
+ packet (bytes): packet
+ offset (int): offset in message
+ rdlength (int): length of rdata
+ parser (int): domain name parser
+ """
+ data = packet[offset:offset+rdlength]
+ return cls(data)
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