public static STUNQueryFullResult Query(Socket socket, IPEndPoint server, STUNQueryType queryType, int ReceiveTimeout)
{
var result = new STUNQueryFullResult(); // the query result
result.Socket = socket;
result.ServerEndPoint = server;
result.NATType = STUNNATType.Unspecified;
result.QueryType = queryType;
var transID = STUNMessage.GenerateTransactionID(); // get a random trans id
var message = new STUNMessage(STUNMessageTypes.BindingRequest, transID); // create a bind request
// send the request to server
socket.SendTo(message.GetBytes(), server);
// we set result local endpoint after calling SendTo,
// because if socket is unbound, the system will bind it after SendTo call.
result.LocalEndPoint = socket.LocalEndPoint as IPEndPoint;
// wait for response
var responseBuffer = STUNUtils.Receive(socket, ReceiveTimeout);
// didn't receive anything
if (responseBuffer == null)
{
result.QueryError = STUNQueryError.Timedout;
return(result);
}
// try to parse message
if (!message.TryParse(responseBuffer))
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
// check trans id
if (!STUNUtils.ByteArrayCompare(message.TransactionID, transID))
{
result.QueryError = STUNQueryError.BadTransactionID;
return(result);
}
// finds error-code attribute, used in case of binding error
var errorAttr = message.Attributes.FirstOrDefault(p => p is STUNErrorCodeAttribute)
as STUNErrorCodeAttribute;
// if server responsed our request with error
if (message.MessageType == STUNMessageTypes.BindingErrorResponse)
{
if (errorAttr == null)
{
// we count a binding error without error-code attribute as bad response (no?)
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
result.QueryError = STUNQueryError.ServerError;
result.ServerError = errorAttr.Error;
result.ServerErrorPhrase = errorAttr.Phrase;
return(result);
}
// return if receive something else binding response
if (message.MessageType != STUNMessageTypes.BindingResponse)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
// not used for now.
var changedAddr =
message.Attributes.FirstOrDefault(p => p is STUNChangedAddressAttribute) as
STUNChangedAddressAttribute;
// find mapped address attribue in message
// this attribue should present
var mappedAddressAttr = message.Attributes.FirstOrDefault(p => p is STUNMappedAddressAttribute)
as STUNMappedAddressAttribute;
if (mappedAddressAttr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
else
{
result.PublicEndPoint = mappedAddressAttr.EndPoint;
}
// stop querying and return the public ip if user just wanted to know public ip
if (queryType == STUNQueryType.PublicIP)
{
result.QueryError = STUNQueryError.None;
return(result);
}
// if our local ip and port equals to mapped address
if (mappedAddressAttr.EndPoint.Equals(socket.LocalEndPoint))
{
// we send to a binding request again but with change-request attribute
// that tells to server to response us with different endpoint
message = new STUNMessage(STUNMessageTypes.BindingRequest, transID);
message.Attributes.Add(new STUNChangeRequestAttribute(true, true));
socket.SendTo(message.GetBytes(), server);
responseBuffer = STUNUtils.Receive(socket, ReceiveTimeout);
// if we didnt receive a response
if (responseBuffer == null)
{
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.SymmetricUDPFirewall;
return(result);
}
if (!message.TryParse(responseBuffer))
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
if (!STUNUtils.ByteArrayCompare(message.TransactionID, transID))
{
result.QueryError = STUNQueryError.BadTransactionID;
return(result);
}
if (message.MessageType == STUNMessageTypes.BindingResponse)
{
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.OpenInternet;
return(result);
}
if (message.MessageType == STUNMessageTypes.BindingErrorResponse)
{
errorAttr =
message.Attributes.FirstOrDefault(p => p is STUNErrorCodeAttribute) as
STUNErrorCodeAttribute;
if (errorAttr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
result.QueryError = STUNQueryError.ServerError;
result.ServerError = errorAttr.Error;
result.ServerErrorPhrase = errorAttr.Phrase;
return(result);
}
// the message type is wrong
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
message = new STUNMessage(STUNMessageTypes.BindingRequest, transID);
message.Attributes.Add(new STUNChangeRequestAttribute(true, true));
var testmsg = new STUNMessage(STUNMessageTypes.BindingRequest, null);
testmsg.Parse(message.GetBytes());
socket.SendTo(message.GetBytes(), server);
responseBuffer = STUNUtils.Receive(socket, ReceiveTimeout);
if (responseBuffer != null)
{
if (!message.TryParse(responseBuffer))
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
if (!STUNUtils.ByteArrayCompare(message.TransactionID, transID))
{
result.QueryError = STUNQueryError.BadTransactionID;
return(result);
}
if (message.MessageType == STUNMessageTypes.BindingResponse)
{
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.FullCone;
return(result);
}
if (message.MessageType == STUNMessageTypes.BindingErrorResponse)
{
errorAttr =
message.Attributes.FirstOrDefault(p => p is STUNErrorCodeAttribute) as
STUNErrorCodeAttribute;
if (errorAttr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
result.QueryError = STUNQueryError.ServerError;
result.ServerError = errorAttr.Error;
result.ServerErrorPhrase = errorAttr.Phrase;
return(result);
}
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
// if user only wanted to know the NAT is open or not
if (queryType == STUNQueryType.OpenNAT)
{
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.Unspecified;
return(result);
}
// we now need changed-address attribute
// because we send our request to this address instead of the first server address
if (changedAddr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
else
{
server = changedAddr.EndPoint;
}
message = new STUNMessage(STUNMessageTypes.BindingRequest, transID);
socket.SendTo(message.GetBytes(), server);
responseBuffer = STUNUtils.Receive(socket, ReceiveTimeout);
if (responseBuffer == null)
{
result.QueryError = STUNQueryError.Timedout;
return(result);
}
if (!message.TryParse(responseBuffer))
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
if (!STUNUtils.ByteArrayCompare(message.TransactionID, transID))
{
result.QueryError = STUNQueryError.BadTransactionID;
return(result);
}
errorAttr =
message.Attributes.FirstOrDefault(p => p is STUNErrorCodeAttribute) as STUNErrorCodeAttribute;
if (message.MessageType == STUNMessageTypes.BindingErrorResponse)
{
if (errorAttr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
result.QueryError = STUNQueryError.ServerError;
result.ServerError = errorAttr.Error;
result.ServerErrorPhrase = errorAttr.Phrase;
return(result);
}
if (message.MessageType != STUNMessageTypes.BindingResponse)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
mappedAddressAttr = message.Attributes.FirstOrDefault(p => p is STUNMappedAddressAttribute)
as STUNMappedAddressAttribute;
if (mappedAddressAttr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
if (!mappedAddressAttr.EndPoint.Equals(result.PublicEndPoint))
{
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.Symmetric;
result.PublicEndPoint = null;
return(result);
}
message = new STUNMessage(STUNMessageTypes.BindingRequest, transID);
message.Attributes.Add(new STUNChangeRequestAttribute(false, true)); // change port but not ip
socket.SendTo(message.GetBytes(), server);
responseBuffer = STUNUtils.Receive(socket, ReceiveTimeout);
if (responseBuffer == null)
{
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.PortRestricted;
return(result);
}
if (!message.TryParse(responseBuffer))
{
result.QueryError = STUNQueryError.Timedout;
return(result);
}
if (!STUNUtils.ByteArrayCompare(message.TransactionID, transID))
{
result.QueryError = STUNQueryError.BadTransactionID;
return(result);
}
errorAttr = message.Attributes.FirstOrDefault(p => p is STUNErrorCodeAttribute)
as STUNErrorCodeAttribute;
if (message.MessageType == STUNMessageTypes.BindingErrorResponse)
{
if (errorAttr == null)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
result.QueryError = STUNQueryError.ServerError;
result.ServerError = errorAttr.Error;
result.ServerErrorPhrase = errorAttr.Phrase;
return(result);
}
if (message.MessageType != STUNMessageTypes.BindingResponse)
{
result.QueryError = STUNQueryError.BadResponse;
return(result);
}
result.QueryError = STUNQueryError.None;
result.NATType = STUNNATType.Restricted;
return(result);
}