Writing Data to Poll Invalid Socket Causes Uncatchable Exception - c++

Question

I am working on a game server that uses sockets and implemented a polling function that sends the message "[POLL]" over all player sockets in a lobby every second to notify the player clients that their connection is still alive.
If I disconnect on the client-side the socket is still polled with no errors, however, if I create a new connection with the same client (Gets a new FD and is added to the map as a second player), the whole server crashes without any exceptions/warnings/messages when it attempts to write to the previous socket FD. My call to Write on the socket is wrapped in a try/catch that doesn't catch any exceptions and, when debugging using gdb, I am not given any error messaging.
This is the Socket Write function:
int Socket::Write(ByteArray const& buffer)
{
if (!open)
{
return -1;
}
// Convert buffer to raw char array
char* raw = new char[buffer.v.size()];
for (int i=0; i < buffer.v.size(); i++)
{
raw[i] = buffer.v[i];
}
// Perform the write operation
int returnValue = write(GetFD(), raw, buffer.v.size()); // <- Crashes program
if (returnValue <= 0)
{
open = false;
}
return returnValue;
}
And this is the Poll function (Players are stored in a map of uint -> Socket*):
/*
Polls all connected players to tell them
to keep their connections alive.
*/
void Lobby::Poll()
{
playerMtx.lock();
for (auto it = players.begin(); it != players.end(); it++)
{
try
{
if (it->second != nullptr && it->second->IsOpen())
{
it->second->Write("[POLL]");
}
}
catch (...)
{
std::cout << "Failed to write to " << it->first << std::endl;
}
}
playerMtx.unlock();
}
I would expect to see the "Failed to write to " message but instead the entire server program exits with no messaging. What could be happening here?

Answer 1

I was unable to find a reason for the program crashing in the call to write but I was able to find a workaround.
I perform a poll operation on the file descriptor prior to calling write and I query the POLLNVAL event. If I receive a nonzero value, the FD is now invalid.
// Check if FD is valid
struct pollfd pollFd;
pollFd.fd = GetFD();
pollFd.events = POLLNVAL;
if (poll(&pollFd, 1, 0) > 0)
{
open = false;
return -1;
}