::getpeername() returns error code 10057 (on a connected socket)

Question

Hi, I am blocked on this issue and cannot find a solution by myself. Maybe someone has encountered a similar issue and could provide some hints.
Calling ::getpeername() (Win 7 x64) on an accepted (and open!) socket connection returns error code 10057 (for code details, please see the code snippet attached):
"A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied."
Any ideas why ::getpeername() fails with 10057 although ::getsockopt() says the socket is connected?
Best regards, M.
--- sample code snippet - begin - error handling left out for simplicity ---
    //accept call looks like this (call is asynchronous!):
    BOOL res = ::AcceptEx(_listenSocket, _socket, &_addrBuffer[0],0, 16+sizeof(SOCKADDR_STORAGE), 16+sizeof(SOCKADDR_STORAGE), &transfered, (LPOVERLAPPED)&_ov);
    // wait until the (previously accepted) socket is connected:
    INT seconds = 0;
    INT bytes = sizeof(seconds);
    int iResult = 0;
    do
      iResult = ::getsockopt(_socket, SOL_SOCKET, SO_CONNECT_TIME, (char *)&seconds, (PINT)&bytes);
    } while (seconds == -1 && iResult != SOCKET_ERROR);
    // now the socket should be connected, let's call ::getpeername():
    sockaddr remoteAddr = { 0 };
    socklen_t peeraddrlen = sizeof(remoteAddr);
    if (::getpeername(_socket, &remoteAddr, &peeraddrlen) == SOCKET_ERROR)
       int errno = getLastSocketError(); // this errno is 10057
--- code snippet - end ---

Answer 1

You also have to set the SO_UPDATE_ACCEPT_CONTEXT  option on the socket before you can use getpeername.  Mike L [MSFT] has provided a
community addition note (entitled "Does not work on accepted sockets without calling setsockopt() first") to
the documentation of getpeername to this effect.
The details of this particular quirk are described in the documentation for AcceptEx.
[See also GetAcceptExSockaddrs]