private byte[] GetQuery(byte[] query,int queryID)
{
byte[] retVal = null;
try
{
int helper = 0;
int count = 0;
while(count < 10){
if(count > m_DnsServers.Length){
helper = 0;
}
byte[] reply = QueryServer(query,m_DnsServers[helper]);
Dns_Answers answers = new Dns_Answers();
// If reply is ok, return it
if(reply != null && answers.ParseAnswers(reply,queryID)){
return reply;
}
count++;
helper++;
}
}
catch{
}
return retVal;
}
/// <summary>
/// Gets MX records.(MX records are sorted by preference, lower array element is prefered)
/// </summary>
/// <param name="domain"></param>
/// <param name="mxRecords"></param>
/// <returns></returns>
public DnsReplyCode GetMXRecords(string domain,out MX_Record[] mxRecords)
{
mxRecords = null;
//--- Try to get MX records from cache
if(m_UseDnsCache){
mxRecords = DnsCache.GetMXFromCache(domain);
if(mxRecords != null){
// Console.WriteLine("domain:" + domain + " from cahce.");
return DnsReplyCode.Ok;
}
}
//------------------------------------//
Dns_Header header = new Dns_Header(DnsEx.ID,OPCODE.IQUERY);
Dns_Query query = new Dns_Query(domain,QTYPE.MX,1);
byte[] bQuery = query.GetQuery(header);
byte[] reply = GetQuery(bQuery,header.ID);
if(reply != null){
Dns_Answers answers = new Dns_Answers();
if(answers.ParseAnswers(reply,header.ID)){
mxRecords = answers.GetMxRecordsFromAnswers();
if(mxRecords != null){
// Add to cache
DnsCache.AddMXToCache(domain,mxRecords);
return DnsReplyCode.Ok;
}
else{
return DnsReplyCode.NoEntries;
}
}
}
return DnsReplyCode.TempError;
}