/// <summary>
/// Initiates an asynchronous operation to authenticate user credentials.
/// </summary>
/// <param name="realm">Specifies the authentication scope.</param>
/// <param name="account">The account.</param>
/// <param name="password">The password.</param>
/// <param name="callback">The delegate to be called when the operation completes (or <c>null</c>).</param>
/// <param name="state">Application defined state (or <c>null</c>).</param>
/// <returns>The <see cref="IAsyncResult" /> instance to be used to track the operation.</returns>
/// <remarks>
/// <note>
/// All successful calls to <see cref="BeginAuthenticate" /> must eventually be
/// matched by a call to <see cref="EndAuthenticate" />.
/// </note>
/// </remarks>
public IAsyncResult BeginAuthenticate(string realm, string account, string password, AsyncCallback callback, object state)
{
AsyncResult arAuth = new AsyncResult(null, callback, state);
AuthTransaction transaction;
RadiusPacket packet;
string userName;
int ID;
IPEndPoint binding;
using (TimedLock.Lock(this))
{
userName = Helper.GetUserName(realmFormat, realm, account);
ID = GetTransactionID();
if (ID == -1)
{
throw new RadiusException("RADIUS client cannot track more than 256 simultaneous authentication requests.");
}
binding = GetServerBinding(ref serverPos);
if (binding == NetworkBinding.Any)
{
throw new RadiusException("None of the RADIUS server hosts resolve to an IP address.");
}
packet = new RadiusPacket(RadiusCode.AccessRequest, ID, Crypto.Rand(16));
packet.Attributes.Add(new RadiusAttribute(RadiusAttributeType.UserName, userName));
packet.Attributes.Add(new RadiusAttribute(RadiusAttributeType.UserPassword, packet.EncryptUserPassword(password, secret)));
packet.Attributes.Add(new RadiusAttribute(RadiusAttributeType.NasIpAddress, nasIPAddress));
transaction = new AuthTransaction(userName, packet, serverPos, SysTime.Now + retryInterval, arAuth);;
transactions[ID] = transaction;
sock.SendTo(transaction.Packet.ToArray(), binding);
arAuth.Result = null;
arAuth.Started();
}
return(arAuth);
}