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StunClient.cs
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StunClient.cs
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using System;
using System.Net.Sockets;
using System.Net;
using System.Text;
namespace p2pcopy
{
/// <summary>
/// This enum specifies STUN message type.
/// </summary>
internal enum StunMessageType
{
/// <summary>
/// STUN message is binding request.
/// </summary>
BindingRequest = 0x0001,
/// <summary>
/// STUN message is binding request response.
/// </summary>
BindingResponse = 0x0101,
/// <summary>
/// STUN message is binding requesr error response.
/// </summary>
BindingErrorResponse = 0x0111,
/// <summary>
/// STUN message is "shared secret" request.
/// </summary>
SharedSecretRequest = 0x0002,
/// <summary>
/// STUN message is "shared secret" request response.
/// </summary>
SharedSecretResponse = 0x0102,
/// <summary>
/// STUN message is "shared secret" request error response.
/// </summary>
SharedSecretErrorResponse = 0x0112,
}
/// <summary>
/// This class implements STUN ERROR-CODE. Defined in RFC 3489 11.2.9.
/// </summary>
internal class STUN_t_ErrorCode
{
int m_Code = 0;
string m_ReasonText = "";
/// <summary>
/// Default constructor.
/// </summary>
/// <param name="code">Error code.</param>
/// <param name="reasonText">Reason text.</param>
internal STUN_t_ErrorCode(int code, string reasonText)
{
m_Code = code;
m_ReasonText = reasonText;
}
#region Properties Implementation
/// <summary>
/// Gets or sets error code.
/// </summary>
internal int Code
{
get { return m_Code; }
set { m_Code = value; }
}
/// <summary>
/// Gets reason text.
/// </summary>
internal string ReasonText
{
get { return m_ReasonText; }
set { m_ReasonText = value; }
}
#endregion
}
/// <summary>
/// This class implements STUN CHANGE-REQUEST attribute. Defined in RFC 3489 11.2.4.
/// </summary>
internal class StunChangeRequest
{
bool m_ChangeIP = true;
bool m_ChangePort = true;
/// <summary>
/// Default constructor.
/// </summary>
/// <param name="changeIP">Specifies if STUN server must
/// send response to different IP than request was received.</param>
/// <param name="changePort">Specifies if STUN server must
/// send response to different port than request was received.</param>
internal StunChangeRequest(bool changeIP, bool changePort)
{
m_ChangeIP = changeIP;
m_ChangePort = changePort;
}
/// <summary>
/// Gets or sets if STUN server must send response
/// to different IP than request was received.
/// </summary>
internal bool ChangeIP
{
get { return m_ChangeIP; }
set { m_ChangeIP = value; }
}
/// <summary>
/// Gets or sets if STUN server must send response
/// to different port than request was received.
/// </summary>
internal bool ChangePort
{
get { return m_ChangePort; }
set { m_ChangePort = value; }
}
}
/// <summary>
/// Implements STUN message. Defined in RFC 3489.
/// </summary>
internal class StunMessage
{
/// <summary>
/// Specifies STUN attribute type.
/// </summary>
enum AttributeType
{
MappedAddress = 0x0001,
ResponseAddress = 0x0002,
ChangeRequest = 0x0003,
SourceAddress = 0x0004,
ChangedAddress = 0x0005,
Username = 0x0006,
Password = 0x0007,
MessageIntegrity = 0x0008,
ErrorCode = 0x0009,
UnknownAttribute = 0x000A,
ReflectedFrom = 0x000B,
XorMappedAddress = 0x8020,
XorOnly = 0x0021,
ServerName = 0x8022,
}
/// <summary>
/// Specifies IP address family.
/// </summary>
enum IPFamily
{
IPv4 = 0x01,
IPv6 = 0x02,
}
StunMessageType m_Type = StunMessageType.BindingRequest;
Guid m_pTransactionID = Guid.Empty;
IPEndPoint m_pMappedAddress = null;
IPEndPoint m_pResponseAddress = null;
StunChangeRequest m_pChangeRequest = null;
IPEndPoint m_pSourceAddress = null;
IPEndPoint m_pChangedAddress = null;
string m_UserName = null;
string m_Password = null;
STUN_t_ErrorCode m_pErrorCode = null;
IPEndPoint m_pReflectedFrom = null;
string m_ServerName = null;
/// <summary>
/// Default constructor.
/// </summary>
internal StunMessage()
{
m_pTransactionID = Guid.NewGuid();
}
/// <summary>
/// Parses STUN message from raw data packet.
/// </summary>
/// <param name="data">Raw STUN message.</param>
internal void Parse(byte[] data)
{
/* RFC 3489 11.1.
All STUN messages consist of a 20 byte header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| STUN Message Type | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Transaction ID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The message length is the count, in bytes, of the size of the
message, not including the 20 byte header.
*/
if (data.Length < 20)
{
throw new ArgumentException("Invalid STUN message value !");
}
int offset = 0;
//--- message header --------------------------------------------------
// STUN Message Type
int messageType = (data[offset++] << 8 | data[offset++]);
if (messageType == (int)StunMessageType.BindingErrorResponse)
{
m_Type = StunMessageType.BindingErrorResponse;
}
else if (messageType == (int)StunMessageType.BindingRequest)
{
m_Type = StunMessageType.BindingRequest;
}
else if (messageType == (int)StunMessageType.BindingResponse)
{
m_Type = StunMessageType.BindingResponse;
}
else if (messageType == (int)StunMessageType.SharedSecretErrorResponse)
{
m_Type = StunMessageType.SharedSecretErrorResponse;
}
else if (messageType == (int)StunMessageType.SharedSecretRequest)
{
m_Type = StunMessageType.SharedSecretRequest;
}
else if (messageType == (int)StunMessageType.SharedSecretResponse)
{
m_Type = StunMessageType.SharedSecretResponse;
}
else
{
throw new ArgumentException("Invalid STUN message type value !");
}
// Message Length
int messageLength = (data[offset++] << 8 | data[offset++]);
// Transaction ID
byte[] guid = new byte[16];
Array.Copy(data, offset, guid, 0, 16);
m_pTransactionID = new Guid(guid);
offset += 16;
//--- Message attributes ---------------------------------------------
while ((offset - 20) < messageLength)
{
ParseAttribute(data, ref offset);
}
}
/// <summary>
/// Converts this to raw STUN packet.
/// </summary>
/// <returns>Returns raw STUN packet.</returns>
internal byte[] ToByteData()
{
/* RFC 3489 11.1.
All STUN messages consist of a 20 byte header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| STUN Message Type | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Transaction ID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The message length is the count, in bytes, of the size of the
message, not including the 20 byte header.
*/
// We allocate 512 for header, that should be more than enough.
byte[] msg = new byte[512];
int offset = 0;
//--- message header -------------------------------------
// STUN Message Type (2 bytes)
msg[offset++] = (byte)((int)this.Type >> 8);
msg[offset++] = (byte)((int)this.Type & 0xFF);
// Message Length (2 bytes) will be assigned at last.
msg[offset++] = 0;
msg[offset++] = 0;
// Transaction ID (16 bytes)
Array.Copy(m_pTransactionID.ToByteArray(), 0, msg, offset, 16);
offset += 16;
//--- Message attributes ------------------------------------
/* RFC 3489 11.2.
After the header are 0 or more attributes. Each attribute is TLV
encoded, with a 16 bit type, 16 bit length, and variable value:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
if (this.MappedAddress != null)
{
StoreEndPoint(AttributeType.MappedAddress, this.MappedAddress, msg, ref offset);
}
else if (this.ResponseAddress != null)
{
StoreEndPoint(AttributeType.ResponseAddress, this.ResponseAddress, msg, ref offset);
}
else if (this.ChangeRequest != null)
{
/*
The CHANGE-REQUEST attribute is used by the client to request that
the server use a different address and/or port when sending the
response. The attribute is 32 bits long, although only two bits (A
and B) are used:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A B 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The meaning of the flags is:
A: This is the "change IP" flag. If true, it requests the server
to send the Binding Response with a different IP address than the
one the Binding Request was received on.
B: This is the "change port" flag. If true, it requests the
server to send the Binding Response with a different port than the
one the Binding Request was received on.
*/
// Attribute header
msg[offset++] = (int)AttributeType.ChangeRequest >> 8;
msg[offset++] = (int)AttributeType.ChangeRequest & 0xFF;
msg[offset++] = 0;
msg[offset++] = 4;
msg[offset++] = 0;
msg[offset++] = 0;
msg[offset++] = 0;
msg[offset++] = (byte)(Convert.ToInt32(this.ChangeRequest.ChangeIP) << 2 | Convert.ToInt32(this.ChangeRequest.ChangePort) << 1);
}
else if (this.SourceAddress != null)
{
StoreEndPoint(AttributeType.SourceAddress, this.SourceAddress, msg, ref offset);
}
else if (this.ChangedAddress != null)
{
StoreEndPoint(AttributeType.ChangedAddress, this.ChangedAddress, msg, ref offset);
}
else if (this.UserName != null)
{
byte[] userBytes = Encoding.ASCII.GetBytes(this.UserName);
// Attribute header
msg[offset++] = (int)AttributeType.Username >> 8;
msg[offset++] = (int)AttributeType.Username & 0xFF;
msg[offset++] = (byte)(userBytes.Length >> 8);
msg[offset++] = (byte)(userBytes.Length & 0xFF);
Array.Copy(userBytes, 0, msg, offset, userBytes.Length);
offset += userBytes.Length;
}
else if (this.Password != null)
{
byte[] userBytes = Encoding.ASCII.GetBytes(this.UserName);
// Attribute header
msg[offset++] = (int)AttributeType.Password >> 8;
msg[offset++] = (int)AttributeType.Password & 0xFF;
msg[offset++] = (byte)(userBytes.Length >> 8);
msg[offset++] = (byte)(userBytes.Length & 0xFF);
Array.Copy(userBytes, 0, msg, offset, userBytes.Length);
offset += userBytes.Length;
}
else if (this.ErrorCode != null)
{
/* 3489 11.2.9.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 |Class| Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase (variable) ..
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
byte[] reasonBytes = Encoding.ASCII.GetBytes(this.ErrorCode.ReasonText);
// Header
msg[offset++] = 0;
msg[offset++] = (int)AttributeType.ErrorCode;
msg[offset++] = 0;
msg[offset++] = (byte)(4 + reasonBytes.Length);
// Empty
msg[offset++] = 0;
msg[offset++] = 0;
// Class
msg[offset++] = (byte)Math.Floor((double)(this.ErrorCode.Code / 100));
// Number
msg[offset++] = (byte)(this.ErrorCode.Code & 0xFF);
// ReasonPhrase
Array.Copy(reasonBytes, msg, reasonBytes.Length);
offset += reasonBytes.Length;
}
else if (this.ReflectedFrom != null)
{
StoreEndPoint(AttributeType.ReflectedFrom, this.ReflectedFrom, msg, ref offset);
}
// Update Message Length. NOTE: 20 bytes header not included.
msg[2] = (byte)((offset - 20) >> 8);
msg[3] = (byte)((offset - 20) & 0xFF);
// Make reatval with actual size.
byte[] retVal = new byte[offset];
Array.Copy(msg, retVal, retVal.Length);
return retVal;
}
/// <summary>
/// Parses attribute from data.
/// </summary>
/// <param name="data">SIP message data.</param>
/// <param name="offset">Offset in data.</param>
void ParseAttribute(byte[] data, ref int offset)
{
/* RFC 3489 11.2.
Each attribute is TLV encoded, with a 16 bit type, 16 bit length, and variable value:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
// Type
AttributeType type = (AttributeType)(data[offset++] << 8 | data[offset++]);
// Length
int length = (data[offset++] << 8 | data[offset++]);
// MAPPED-ADDRESS
if (type == AttributeType.MappedAddress)
{
m_pMappedAddress = ParseEndPoint(data, ref offset);
}
// RESPONSE-ADDRESS
else if (type == AttributeType.ResponseAddress)
{
m_pResponseAddress = ParseEndPoint(data, ref offset);
}
// CHANGE-REQUEST
else if (type == AttributeType.ChangeRequest)
{
/*
The CHANGE-REQUEST attribute is used by the client to request that
the server use a different address and/or port when sending the
response. The attribute is 32 bits long, although only two bits (A
and B) are used:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A B 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The meaning of the flags is:
A: This is the "change IP" flag. If true, it requests the server
to send the Binding Response with a different IP address than the
one the Binding Request was received on.
B: This is the "change port" flag. If true, it requests the
server to send the Binding Response with a different port than the
one the Binding Request was received on.
*/
// Skip 3 bytes
offset += 3;
m_pChangeRequest = new StunChangeRequest((data[offset] & 4) != 0, (data[offset] & 2) != 0);
offset++;
}
// SOURCE-ADDRESS
else if (type == AttributeType.SourceAddress)
{
m_pSourceAddress = ParseEndPoint(data, ref offset);
}
// CHANGED-ADDRESS
else if (type == AttributeType.ChangedAddress)
{
m_pChangedAddress = ParseEndPoint(data, ref offset);
}
// USERNAME
else if (type == AttributeType.Username)
{
m_UserName = Encoding.Default.GetString(data, offset, length);
offset += length;
}
// PASSWORD
else if (type == AttributeType.Password)
{
m_Password = Encoding.Default.GetString(data, offset, length);
offset += length;
}
// MESSAGE-INTEGRITY
else if (type == AttributeType.MessageIntegrity)
{
offset += length;
}
// ERROR-CODE
else if (type == AttributeType.ErrorCode)
{
/* 3489 11.2.9.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 |Class| Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase (variable) ..
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
int errorCode = (data[offset + 2] & 0x7) * 100 + (data[offset + 3] & 0xFF);
m_pErrorCode = new STUN_t_ErrorCode(errorCode, Encoding.Default.GetString(data, offset + 4, length - 4));
offset += length;
}
// UNKNOWN-ATTRIBUTES
else if (type == AttributeType.UnknownAttribute)
{
offset += length;
}
// REFLECTED-FROM
else if (type == AttributeType.ReflectedFrom)
{
m_pReflectedFrom = ParseEndPoint(data, ref offset);
}
// XorMappedAddress
// XorOnly
// ServerName
else if (type == AttributeType.ServerName)
{
m_ServerName = Encoding.Default.GetString(data, offset, length);
offset += length;
}
// Unknown
else
{
offset += length;
}
}
/// <summary>
/// Pasrses IP endpoint attribute.
/// </summary>
/// <param name="data">STUN message data.</param>
/// <param name="offset">Offset in data.</param>
/// <returns>Returns parsed IP end point.</returns>
IPEndPoint ParseEndPoint(byte[] data, ref int offset)
{
/*
It consists of an eight bit address family, and a sixteen bit
port, followed by a fixed length value representing the IP address.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x x x x x x x x| Family | Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
// Skip family
offset++;
offset++;
// Port
int port = (data[offset++] << 8 | data[offset++]);
// Address
byte[] ip = new byte[4];
ip[0] = data[offset++];
ip[1] = data[offset++];
ip[2] = data[offset++];
ip[3] = data[offset++];
return new IPEndPoint(new IPAddress(ip), port);
}
/// <summary>
/// Stores ip end point attribute to buffer.
/// </summary>
/// <param name="type">Attribute type.</param>
/// <param name="endPoint">IP end point.</param>
/// <param name="message">Buffer where to store.</param>
/// <param name="offset">Offset in buffer.</param>
void StoreEndPoint(AttributeType type, IPEndPoint endPoint, byte[] message, ref int offset)
{
/*
It consists of an eight bit address family, and a sixteen bit
port, followed by a fixed length value representing the IP address.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x x x x x x x x| Family | Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
// Header
message[offset++] = (byte)((int)type >> 8);
message[offset++] = (byte)((int)type & 0xFF);
message[offset++] = 0;
message[offset++] = 8;
// Unused
message[offset++] = 0;
// Family
message[offset++] = (byte)IPFamily.IPv4;
// Port
message[offset++] = (byte)(endPoint.Port >> 8);
message[offset++] = (byte)(endPoint.Port & 0xFF);
// Address
byte[] ipBytes = endPoint.Address.GetAddressBytes();
message[offset++] = ipBytes[0];
message[offset++] = ipBytes[0];
message[offset++] = ipBytes[0];
message[offset++] = ipBytes[0];
}
/// <summary>
/// Gets STUN message type.
/// </summary>
internal StunMessageType Type
{
get { return m_Type; }
set { m_Type = value; }
}
/// <summary>
/// Gets transaction ID.
/// </summary>
internal Guid TransactionID
{
get { return m_pTransactionID; }
}
/// <summary>
/// Gets or sets IP end point what was actually connected to STUN server. Returns null if not specified.
/// </summary>
internal IPEndPoint MappedAddress
{
get { return m_pMappedAddress; }
set { m_pMappedAddress = value; }
}
/// <summary>
/// Gets or sets IP end point where to STUN client likes to receive response.
/// Value null means not specified.
/// </summary>
internal IPEndPoint ResponseAddress
{
get { return m_pResponseAddress; }
set { m_pResponseAddress = value; }
}
/// <summary>
/// Gets or sets how and where STUN server must send response back to STUN client.
/// Value null means not specified.
/// </summary>
internal StunChangeRequest ChangeRequest
{
get { return m_pChangeRequest; }
set { m_pChangeRequest = value; }
}
/// <summary>
/// Gets or sets STUN server IP end point what sent response to STUN client. Value null
/// means not specified.
/// </summary>
internal IPEndPoint SourceAddress
{
get { return m_pSourceAddress; }
set { m_pSourceAddress = value; }
}
/// <summary>
/// Gets or sets IP end point where STUN server will send response back to STUN client
/// if the "change IP" and "change port" flags had been set in the ChangeRequest.
/// </summary>
internal IPEndPoint ChangedAddress
{
get { return m_pChangedAddress; }
set { m_pChangedAddress = value; }
}
/// <summary>
/// Gets or sets user name. Value null means not specified.
/// </summary>
internal string UserName
{
get { return m_UserName; }
set { m_UserName = value; }
}
/// <summary>
/// Gets or sets password. Value null means not specified.
/// </summary>
internal string Password
{
get { return m_Password; }
set { m_Password = value; }
}
//internal MessageIntegrity
/// <summary>
/// Gets or sets error info. Returns null if not specified.
/// </summary>
internal STUN_t_ErrorCode ErrorCode
{
get { return m_pErrorCode; }
set { m_pErrorCode = value; }
}
/// <summary>
/// Gets or sets IP endpoint from which IP end point STUN server got STUN client request.
/// Value null means not specified.
/// </summary>
internal IPEndPoint ReflectedFrom
{
get { return m_pReflectedFrom; }
set { m_pReflectedFrom = value; }
}
}
/// <summary>
/// This class implements STUN client. Defined in RFC 3489.
/// </summary>
/// <example>
/// <code>
/// // Create new socket for STUN client.
/// Socket socket = new Socket(AddressFamily.InterNetwork,SocketType.Dgram,ProtocolType.Udp);
/// socket.Bind(new IPEndPoint(IPAddress.Any,0));
///
/// // Query STUN server
/// STUN_Result result = STUN_Client.Query("stunserver.org",3478,socket);
/// if(result.NetType != STUN_NetType.UdpBlocked){
/// // UDP blocked or !!!! bad STUN server
/// }
/// else{
/// IPEndPoint publicEP = result.PublicEndPoint;
/// // Do your stuff
/// }
/// </code>
/// </example>
internal class StunClient
{
#region static method Query
/// <summary>
/// Gets NAT info from STUN server.
/// </summary>
/// <param name="host">STUN server name or IP.</param>
/// <param name="port">STUN server port. Default port is 3478.</param>
/// <param name="socket">UDP socket to use.</param>
/// <returns>Returns UDP netwrok info.</returns>
/// <exception cref="Exception">Throws exception if unexpected error happens.</exception>
internal static StunResult Query(string host, int port, Socket socket)
{
if (host == null)
{
throw new ArgumentNullException("host");
}
if (socket == null)
{
throw new ArgumentNullException("socket");
}
if (port < 1)
{
throw new ArgumentException("Port value must be >= 1 !");
}
if (socket.ProtocolType != ProtocolType.Udp)
{
throw new ArgumentException("Socket must be UDP socket !");
}
IPEndPoint remoteEndPoint = new IPEndPoint(System.Net.Dns.GetHostAddresses(host)[0], port);
socket.ReceiveTimeout = 3000;
socket.SendTimeout = 3000;
/*
In test I, the client sends a STUN Binding Request to a server, without any flags set in the
CHANGE-REQUEST attribute, and without the RESPONSE-ADDRESS attribute. This causes the server
to send the response back to the address and port that the request came from.
In test II, the client sends a Binding Request with both the "change IP" and "change port" flags
from the CHANGE-REQUEST attribute set.
In test III, the client sends a Binding Request with only the "change port" flag set.
+--------+
| Test |
| I |
+--------+
|
|
V
/\ /\
N / \ Y / \ Y +--------+
UDP <-------/Resp\--------->/ IP \------------->| Test |
Blocked \ ? / \Same/ | II |
\ / \? / +--------+
\/ \/ |
| N |
| V
V /\
+--------+ Sym. N / \
| Test | UDP <---/Resp\
| II | Firewall \ ? /
+--------+ \ /
| \/
V |Y
/\ /\ |
Symmetric N / \ +--------+ N / \ V
NAT <--- / IP \<-----| Test |<--- /Resp\ Open
\Same/ | I | \ ? / Internet
\? / +--------+ \ /
\/ \/
| |Y
| |
| V
| Full
| Cone
V /\
+--------+ / \ Y
| Test |------>/Resp\---->Restricted
| III | \ ? /
+--------+ \ /
\/
|N
| Port
+------>Restricted
*/
// Test I
StunMessage test1 = new StunMessage();
test1.Type = StunMessageType.BindingRequest;
StunMessage test1response = DoTransaction(test1, socket, remoteEndPoint);
// UDP blocked.
if (test1response == null)
{
return new StunResult(StunNetType.UdpBlocked, null);
}
else
{
// Test II
StunMessage test2 = new StunMessage();
test2.Type = StunMessageType.BindingRequest;
test2.ChangeRequest = new StunChangeRequest(true, true);
// No NAT.
if (socket.LocalEndPoint.Equals(test1response.MappedAddress))
{
StunMessage test2Response = DoTransaction(test2, socket, remoteEndPoint);
// Open Internet.
if (test2Response != null)
{
return new StunResult(StunNetType.OpenInternet, test1response.MappedAddress);
}
// Symmetric UDP firewall.
else
{
return new StunResult(StunNetType.SymmetricUdpFirewall, test1response.MappedAddress);
}
}
// NAT
else
{
StunMessage test2Response = DoTransaction(test2, socket, remoteEndPoint);
// Full cone NAT.
if (test2Response != null)
{
return new StunResult(StunNetType.FullCone, test1response.MappedAddress);
}
else
{
/*
If no response is received, it performs test I again, but this time, does so to
the address and port from the CHANGED-ADDRESS attribute from the response to test I.
*/
// Test I(II)
StunMessage test12 = new StunMessage();
test12.Type = StunMessageType.BindingRequest;
StunMessage test12Response = DoTransaction(test12, socket, test1response.ChangedAddress);
if (test12Response == null)
{
throw new Exception("STUN Test I(II) dind't get resonse !");
}
else
{
// Symmetric NAT
if (!test12Response.MappedAddress.Equals(test1response.MappedAddress))
{
return new StunResult(StunNetType.Symmetric, test1response.MappedAddress);
}
else
{
// Test III
StunMessage test3 = new StunMessage();
test3.Type = StunMessageType.BindingRequest;
test3.ChangeRequest = new StunChangeRequest(false, true);
StunMessage test3Response = DoTransaction(test3, socket, test1response.ChangedAddress);
// Restricted
if (test3Response != null)
{
return new StunResult(StunNetType.RestrictedCone, test1response.MappedAddress);
}
// Port restricted
else
{
return new StunResult(StunNetType.PortRestrictedCone, test1response.MappedAddress);
}
}
}
}
}
}
}
#endregion
#region method DoTransaction
/// <summary>
/// Does STUN transaction. Returns transaction response or null if transaction failed.