/// <summary>
/// Parses attribute from data.
/// </summary>
/// <param name="data">SIP message data.</param>
/// <param name="offset">Offset in data.</param>
private 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 STUN_t_ChangeRequest((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>
/// Parses attribute from data.
/// </summary>
/// <param name="data">SIP message data.</param>
/// <param name="offset">Offset in data.</param>
private 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 STUN_t_ChangeRequest((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;
}
}