无法在 NS3 上调用 Tcp 套接字接收回调函数

Question

I am new with NS3. I am trying to create a custom application and currently have a difficulty on calling a Socket callback function using socket->SetRecvCallback. This problem occur while I use TcpSocketFactory, another socket such as UDP does not produce this issue.

On main

Ptr<Socket> ns3TcpSocket = Socket::CreateSocket(nodes.Get(0), TcpSocketFactory::GetTypeId());

Custom Tcp Application Class

this->socket->SetRecvCallback(MakeCallback(&CustomTcpApplication::RecvCallback, this));
this->socket->SetSendCallback(MakeCallback(&CustomTcpApplication::WriteUntilBufferFull, this));

My callback function

void CustomTcpApplication::RecvCallback(Ptr<Socket> socket)
{
    std::cout << "On Receive Callback Function" << std::endl;
}


void CustomTcpApplication::WriteUntilBufferFull(Ptr<Socket> localSocket, uint32_t txSpace)
{
    std::cout << "On Send Callback Function" << std::endl;
}

Also. I read from this answer to implements SetAcceptCallback, ns-3 wlan grid TCP not working while UDP is

this->socket->SetAcceptCallback(MakeNullCallback<bool, Ptr<Socket>, const Address &>(), MakeCallback(&CustomTcpApplication::Accept, this));

Callback Function

void CustomTcpApplication::Accept(Ptr<Socket> socket, const ns3::Address& from)
{
    std::cout << "Connection accepted" << std::endl;
    socket->SetRecvCallback(MakeCallback(&CustomTcpApplication::MainRecvCallback, this));
}

However, I still cannot log it on the function. Did I missing any step?

Answer 1

I got the same problem today. After tracing codes for hours, I found that there is no native support for TCP data receiving callback.

The tcp-socket-base.cc forks a new TcpSocketBase object for the following data transmission in TcpSocketBase::ProcessListen(). The copy constructor of TcpSocketBase resets new socket's callback functions including m_receivedData . That's why data receiving callback doesn't work for TCP.

A simple workaround is to reserve the callback variable from original TcpSocketBase and make m_receivedDataTCP public in src/network/model/socket.h.

TcpSocketBase::TcpSocketBase (const TcpSocketBase& sock)
{
   ...
   m_receivedDataTCP = sock.m_receivedDataTCP;
}