/// <summary>
/// Resolves and returns a <see cref="AK.Net.Dns.DnsName"/> instance for
/// each of the authoritative name servers for the specified
/// <paramref name="domain"/>.
/// </summary>
/// <param name="domain">The domain.</param>
/// <returns>
/// The list of <see cref="AK.Net.Dns.DnsName"/> instances for each of the
/// authoritative name servers for the specified <paramref name="domain"/>.
/// </returns>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="domain"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsTransportException">
/// Thrown when a transport error occurs.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsResolutionException">
/// Thrown when an error occurs during the resolution, such as the query
/// not being answered.
/// </exception>
public virtual DnsName[] GetNameServers(DnsName domain)
{
DnsName qname = AppendNameSuffix(domain);
DnsReply reply = Resolve(new DnsQuestion(qname, DnsQueryType.NS, DnsQueryClass.IN));
return(reply.Answers.Where(F.IsNS).Select(x => F.ToNS(x).Domain).ToArray());
}
/// <summary>
/// Sends the specified <see cref="AK.Net.Dns.DnsQuery"/> to the specified
/// end point and return the <see cref="AK.Net.Dns.DnsReply"/>.
/// </summary>
/// <param name="query">The query to send.</param>
/// <param name="endpoint">The transport end point.</param>
/// <returns>
/// The <see cref="AK.Net.Dns.DnsReply"/> to the <see cref="AK.Net.Dns.DnsQuery"/>.
/// </returns>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="endpoint"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsTransportException">
/// Thrown when a transport error occurs.
/// </exception>
public override DnsReply Send(DnsQuery query, IPEndPoint endpoint)
{
Guard.NotNull(endpoint, "endpoint");
DnsReply reply = null;
IDnsTransport transport = SelectTransport(query);
try {
reply = transport.Send(query, endpoint);
} catch (DnsTransportException exc) {
// If the selected transport was TCP, we cannot fail over.
// NOTE this comparison is not thread safe, but at worst it would mean
// the query being sent again.
if (transport == this.TcpTransport)
{
throw;
}
this.Log.Warn("UDP transport failure, failing over to TCP:", exc);
}
if (reply != null)
{
if (!reply.Header.IsTruncated)
{
return(reply);
}
this.Log.InfoFormat("message truncated, failing over to TCP, question={0}", query.Question);
}
return(this.TcpTransport.Send(query, endpoint));
}
/// <summary>
///
/// </summary>
/// <param name="reply">The <see cref="AK.Net.Dns.DnsReply"/> to check.</param>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="reply"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsResolutionException">
/// Thrown when
/// </exception>
protected void AssertIsPositiveReply(DnsReply reply)
{
Guard.NotNull(reply, "reply");
if (reply.Header.ResponseCode != DnsResponseCode.NoError)
{
throw Guard.DnsResolverNegativeResponseCodeReceived(
reply.Header.ResponseCode, reply.Questions.FirstOrDefault());
}
}
public static void Main(string[] args)
{
var nameServers = AKDns.GetNameServers("rcmap.co.uk.");
var mxInfo = AKDns.GetMXInfo("rcmap.co.uk.");
IDnsTransport transport = new DnsUdpTransport();
DnsQuery query = new DnsQuery();
query.Questions.Add(new DnsQuestion("rcmap.co.uk.", DnsQueryType.A, DnsQueryClass.IN));
DnsReply reply = transport.Send(query, new IPEndPoint(IPAddress.Parse("8.8.8.8"), DnsTransport.DnsPort));
}
/// <summary>
/// Attemps to read a <see cref="AK.Net.Dns.DnsReply"/> from the specified
/// <paramref name="buffer"/> and returns a value indicating the result of
/// the operation.
/// </summary>
/// <param name="buffer">The data buffer.</param>
/// <param name="offset">The offset in <paramref name="buffer"/> at which
/// reading begins.</param>
/// <param name="count">The number of bytes available within
/// <paramref name="buffer"/>.</param>
/// <param name="reply">On success, this argument will contain the
/// read <see cref="AK.Net.Dns.DnsReply"/>.</param>
/// <returns><see langword="true"/> if a <see cref="AK.Net.Dns.DnsReply"/>
/// was successfully read from the specified <paramref name="buffer"/>,
/// otherwise; <see langword="false"/>.</returns>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="buffer"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// Thrown when
/// <list type="bullet">
/// <item>
/// <paramref name="offset"/> is negative or greater than the length
/// of <paramref name="buffer"/>
/// </item>
/// <item>
/// <paramref name="count"/> is negative or greater than the length of
/// <paramref name="buffer"/> given <paramref name="offset"/>.
/// </item>
/// </list>
/// </exception>
protected virtual bool TryReadReply(byte[] buffer, int offset, int count,
out DnsReply reply)
{
reply = new DnsReply();
try {
using (DnsWireReader reader = new DnsWireReader(buffer, offset, count))
reply.Read(reader);
} catch (DnsFormatException) {
reply = null;
}
return(reply != null);
}
/// <summary>
/// Resolves and returns an <see cref="System.Net.IPHostEntry"/> for the
/// specified <see cref="System.Net.IPAddress"/>.
/// </summary>
/// <param name="address">The host's IP address.</param>
/// <returns>An <see cref="System.Net.IPHostEntry"/> containing information
/// associated with the host.</returns>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="address"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsTransportException">
/// Thrown when a transport error occurs.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsResolutionException">
/// Thrown when an error occurs during the resolution, such as the query
/// not being answered.
/// </exception>
public virtual IPHostEntry GetHostEntry(IPAddress address)
{
Guard.NotNull(address, "address");
DnsName qname = PtrRecord.MakeName(address);
DnsReply reply = Resolve(new DnsQuestion(qname, DnsQueryType.Ptr, DnsQueryClass.IN));
return(new IPHostEntry()
{
AddressList = new IPAddress[] { address },
Aliases = DnsUtility.EMPTY_STRING_ARRAY,
HostName = (from ptr in reply.Answers
where F.IsPtr(ptr) && ptr.Owner.Equals(qname)
select F.ToPtr(ptr).Domain).FirstOrDefault() ?? null
});
}
/// <summary>
/// Resolves and returns the <see cref="AK.Net.Dns.MXInfo"/> instance for the
/// specified <paramref name="domain"/>.
/// </summary>
/// <param name="domain">The domain name.</param>
/// <returns>The mail exchange information associated with the
/// <paramref name="domain"/>.</returns>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="domain"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsTransportException">
/// Thrown when a transport error occurs.
/// </exception>
/// <exception cref="AK.Net.Dns.DnsResolutionException">
/// Thrown when an error occurs during the resolution, such as the query
/// not being answered.
/// </exception>
public virtual MXInfo GetMXInfo(DnsName domain)
{
DnsName qname = AppendNameSuffix(domain);
DnsReply reply = Resolve(new DnsQuestion(qname, DnsQueryType.MX, DnsQueryClass.IN));
if (reply.Answers.Count > 0)
{
return(new MXInfo(qname,
(from ans in reply.Answers
where F.IsMX(ans)
let mx = F.ToMX(ans)
orderby mx
select mx.Exchange).ToArray()
));
}
return(new MXInfo(domain));
}
/// <summary>
/// Puts the records contained within the specified <paramref name="reply"/>
/// into the cache.
/// </summary>
/// <param name="reply">The reply containing the records to cache.</param>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="reply"/> is <see langword="null"/>.
/// </exception>
public void Put(DnsReply reply)
{
Guard.NotNull(reply, "reply");
}
/// <summary>
/// Attemps to read a <see cref="AK.Net.Dns.DnsReply"/> from the specified
/// <paramref name="buffer"/> and returns a value indicating the result of
/// the operation.
/// </summary>
/// <param name="buffer">The data buffer.</param>
/// <param name="reply">On success, this argument will contain the
/// read <see cref="AK.Net.Dns.DnsReply"/>.</param>
/// <returns><see langword="true"/> if a <see cref="AK.Net.Dns.DnsReply"/>
/// was successfully read from the specified <paramref name="buffer"/>,
/// otherwise; <see langword="false"/>.</returns>
/// <exception cref="System.ArgumentNullException">
/// Thrown when <paramref name="buffer"/> is <see langword="null"/>.
/// </exception>
protected virtual bool TryReadReply(byte[] buffer, out DnsReply reply)
{
Guard.NotNull(buffer, "buffer");
return(TryReadReply(buffer, 0, buffer.Length, out reply));
}
