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Diffstat (limited to 'project2/proj2_s4498062/dns/resource.py')
| -rw-r--r-- | project2/proj2_s4498062/dns/resource.py | 248 |
1 files changed, 248 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..e552c22 --- /dev/null +++ b/project2/proj2_s4498062/dns/resource.py @@ -0,0 +1,248 @@ +""" 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 +import time + +from dns.types import Type + + +class ResourceRecord(object): + """ DNS resource record """ + def __init__(self, name, type_, class_, ttl, rdata, timestamp=None): + """ 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 + self.timestamp = int(timestamp or time.time()) + + def match(self, name=None, type_=None, class_=None, ttl=None): + """Check if the record matches properties""" + return (name is None or self.name == name) and \ + (type_ is None or self.type_ == type_) and \ + (class_ is None or self.class_ == class_) and \ + (ttl is None or self.ttl == ttl) + + def to_bytes(self, offset, composer): + """ Convert ResourceRecord to bytes """ + record = composer.to_bytes(offset, [self.name]) + record += struct.pack("!HHI", self.type_, self.class_, self.ttl) + offset += len(record) + 2 + rdata = self.rdata.to_bytes(offset, composer) + record += struct.pack("!H", len(rdata)) + rdata + return record + + @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, rdlen = struct.unpack_from("!HHIH", packet, offset) + offset += 10 + rdata = RecordData.from_bytes(type_, packet, offset, rdlen, parser) + offset += rdlen + 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): + """Data of an A record""" + + 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): + """Data of a CNAME record""" + + 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): + """Data of an NS record""" + + 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): + """Data of an AAAA record""" + + 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(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_ntop(socket.AF_INET6, packet[offset:offset+16]) + return cls(data) + + +class GenericRecordData(RecordData): + """Data of a generic record""" + + 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(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 = packet[offset:offset+rdlength] + return cls(data) |