/// <summary>
/// Sends query to server.
/// </summary>
/// <param name="timeout">Query timeout in milli seconds.</param>
/// <param name="qname">Query text.</param>
/// <param name="qtype">Query type.</param>
/// <param name="qclass">Query class.</param>
/// <returns>Returns DNS server response.</returns>
private DnsServerResponse QueryServer(int timeout, string qname, QTYPE qtype, int qclass)
{
if (m_DnsServers == null || m_DnsServers.Length == 0)
{
throw new Exception("Dns server isn't specified !");
}
// See if query is in cache
if (m_UseDnsCache)
{
DnsServerResponse resopnse = DnsCache.GetFromCache(qname, (int)qtype);
if (resopnse != null)
{
return(resopnse);
}
}
int queryID = Dns_Client.ID;
byte[] query = CreateQuery(queryID, qname, qtype, qclass);
// Create transcation and start processing it.
using (DnsTransaction transaction = new DnsTransaction(this, queryID, qname, (int)qtype, timeout, query)){
ManualResetEvent wait = new ManualResetEvent(false);
transaction.Timeout += delegate(object s, EventArgs e){
wait.Set();
};
transaction.Completed += delegate(object s, EventArgs e){
wait.Set();
};
m_pTransactions.Add(transaction.ID, transaction);
// Start transaction processing and wait transaction to complete.
transaction.Start();
wait.WaitOne();
// DNS server response received.
if (transaction.Response != null)
{
return(transaction.Response);
}
// No server response - timeout.
else
{
throw new Exception("Timeout - no response from DNS server.");
}
}
}
/// <summary>
/// Is called when IPv6 socket has received data.
/// </summary>
/// <param name="ar">The result of the asynchronous operation.</param>
private void IPv6ReceiveCompleted(IAsyncResult ar)
{
try{
if (m_IsDisposed)
{
return;
}
EndPoint remoteEP = new IPEndPoint(IPAddress.Any, 0);
int count = m_pIPv6Socket.EndReceiveFrom(ar, ref remoteEP);
DnsServerResponse serverResponse = ParseQuery((byte[])ar.AsyncState);
DnsTransaction transaction = null;
// Pass response to transaction.
if (m_pTransactions.TryGetValue(serverResponse.ID, out transaction))
{
transaction.ProcessResponse(serverResponse);
}
// No such transaction or transaction has timed out before answer received.
//else{
//}
// Cache query.
if (m_UseDnsCache && serverResponse.ResponseCode == RCODE.NO_ERROR)
{
DnsCache.AddToCache(transaction.QName, transaction.QType, serverResponse);
}
}
catch {
// Skip receiving socket errors.
}
try{
StartWaitingIPv6Packet();
}
catch {
}
}
public DnsTransaction.ResourceRecord lookup(DnsTransaction.QuestionRecord record)
{
uint qid = getDnsQueryId(record);
using (MySqlCommand sql = new MySqlCommand("SELECT (ttl,data) FROM records WHERE query=@query ORDER BY cached DESC LIMIT 1", db))
{
sql.Parameters.AddWithValue("@query", qid);
sql.Prepare();
using (MySqlDataReader results = sql.ExecuteReader())
{
byte[] chunk = new byte[1024];
long n = 0;
long r;
MemoryStream s = new MemoryStream();
do {
r = results.GetBytes(1, n, chunk, 0,chunk.Length);
s.Write(chunk, 0,(int) r);
} while(r == chunk.Length);
return new DnsTransaction.ResourceRecord(record, results.GetUInt32(0), s.ToArray());
}
}
}
public uint getDnsQueryId(DnsTransaction.QuestionRecord query, uint labelId = 0)
{
if (labelId == 0)
labelId = getDnsLabelId(query.name);
MySqlCommand sql = new MySqlCommand("SELECT (id) FROM queries WHERE label=@label AND type=@type AND class=@class LIMIT 1", db);
sql.Parameters.AddWithValue("@label", labelId.ToString());
sql.Parameters.AddWithValue("@type", (uint)query._type);
sql.Parameters.AddWithValue("@class", (uint)query._class);
sql.Prepare();
object r = sql.ExecuteScalar();
if (r != null)
return (uint)r;
// Doesn't Exist, lets create
sql.CommandText = "INSERT INTO queries (label,type,class) VALUES (@label,@type,@class)";
sql.Prepare();
sql.ExecuteNonQuery();
return (uint)sql.LastInsertedId;
}
