private static byte[] GenerateAnswer(Record rec, SuffixTree names, int startAddr)
{
var answer = new List <byte>();
answer.AddRange(GenerateName(rec.Name, answer.Count, names));
answer.AddRange(To2Bytes((int)rec.Type));
answer.AddRange(To2Bytes(1));
var ttl = rec.ActualTo.Subtract(DateTime.Now).Seconds;
answer.AddRange(To2Bytes(ttl / 65536));
answer.AddRange(To2Bytes(ttl % 65536));
switch (rec.Type)
{
case RecordType.A:
var address4 = (byte[])rec.Data;
answer.AddRange(To2Bytes(4));
answer.AddRange(address4);
break;
case RecordType.AAA:
var address16 = (byte[])rec.Data;
answer.AddRange(To2Bytes(16));
answer.AddRange(address16);
break;
case RecordType.NS:
var nsname = (string)rec.Data;
var nsData = GenerateName(nsname, answer.Count, names);
answer.AddRange(To2Bytes(nsData.Length));
answer.AddRange(nsData);
break;
case RecordType.SOA:
var soaData = (SOAData)rec.Data;
var dat = new List <byte>();
dat.AddRange(GenerateName(soaData.Server, answer.Count + dat.Count, names));
dat.AddRange(GenerateName(soaData.Mail, answer.Count + dat.Count, names));
dat.AddRange(To2Bytes((int)(soaData.Serial / 65536)));
dat.AddRange(To2Bytes((int)(soaData.Serial % 65536)));
dat.AddRange(To2Bytes(soaData.Refresh));
dat.AddRange(To2Bytes(soaData.Retry));
dat.AddRange(To2Bytes(soaData.Expire));
dat.AddRange(To2Bytes(soaData.MinTTL));
answer.AddRange(To2Bytes(dat.Count));
answer.AddRange(dat);
break;
}
return(answer.ToArray());
}
public static byte[] GenerateResponse(Record[] records, Request req)
{
var response = new List <byte>();
var names = new SuffixTree();
response.AddRange(GenerateRequest(req.Questions[0], (short)req.ID, names));
response[6] = (byte)(records.Length / 256);
response[7] = (byte)(records.Length % 256);
foreach (var record in records)
{
response.AddRange(GenerateAnswer(record, names, response.Count));
}
return(response.ToArray());
}
//преобразование имени
//доменное имя, есть набор подимен
//парсер должен сделать следующее
//1. прочитать имя и разбить на зоны
//2. найти максимальное подимя в дереве суффиксов
//3. заменить его на ссылку
//4. остальное написать
public static byte[] GenerateName(string name, int addr, SuffixTree names)
{
var bytes = new List <byte>();
var codes = GenerateZones(name);
int reference = 0;
int suffix = suffix = names.ReadNameAndUpdate(name, ref reference, addr);
foreach (var bs in codes)
{
bytes.Add((byte)bs.Length);
bytes.AddRange(bs);
}
if (suffix > 0)
{
bytes.RemoveRange(bytes.Count - suffix, suffix);
bytes.AddRange(To2Bytes(192 * 256 + reference));
}
return(bytes.ToArray());
}
public static byte[] GenerateRequest(Question quest, short id, SuffixTree names)
{
var request = new List <byte>();
request.AddRange(To2Bytes(id));
request.Add(1); //0... - request, .0000... - opcode (std. query), ...0.. - isn't truncated, ...0. - in't fragmented, ...1 - recursion
request.Add(0); //0... - server supports recursion, .000... - reserved, ...0000 - RCODE (NOError)
request.AddRange(To2Bytes(1)); //questions count
request.AddRange(To2Bytes(0)); //answers count
request.AddRange(To2Bytes(0)); //authoritive RRs count
request.AddRange(To2Bytes(0)); //additional RRs count
//simple single question
int trash = 0;
names.ReadNameAndUpdate(quest.Domain, ref trash, request.Count);
request.AddRange(EncodeDName(quest.Domain)); //name
request.AddRange(To2Bytes((int)quest.Type)); //Type
request.AddRange(To2Bytes(1)); //Class (IN)
return(request.ToArray());
}
