CODEWITHSUNDEEP
c++cnetwork-programmingtcpwinsock2
Youda008
Youda008

Reputation: 1959

Calling accept() causes WSAEFAULT 10014 Bad address

I'm writing a custom TCP server for Windows, using MinGW compiler and winsock2 API.

I have this piece of code:

TCPSocket TCPSocket::accept() {

    TCPSocket clSocket;
    struct sockaddr_in clAddr;
    socklen_t clAddrSize;

    clAddrSize = sizeof(clAddr);

    clSocket.shared->sockFd = ::accept(shared->sockFd, (struct sockaddr *)&clAddr, &clAddrSize);
    if (clSocket.shared->sockFd < 0) {
        printf("failed to accept incoming connection (code: %d)\n", WSAGetLastError());
        throw SocketException(6, "failed to accept incoming connection");
    }

    clSocket.shared->buffer = new byte [BUFFER_SIZE];
    clSocket.shared->curPos = clSocket.shared->endPos = clSocket.shared->buffer;

    return clSocket;

}

However after calling accept() i get

failed to accept incoming connection (code: 10014)

which is according to MSDN:

WSAEFAULT 10014 Bad address. The system detected an invalid pointer address in attempting to use a pointer argument of a call. This error occurs if an application passes an invalid pointer value, or if the length of the buffer is too small. For instance, if the length of an argument, which is a sockaddr structure, is smaller than the sizeof(sockaddr).

I don't see, how these pointers can be bad, they both directly address a local variable. The clAddrSize is initialized and shared->sockFd is initialized in another function

void TCPSocket::listen(uint16_t port, int backlog) {

    struct addrinfo * ainfo;
    char portStr[8];
    int res;

    if (shared->sockFd != -1)
        logicError(1, "socket already initialized, need to close first");

    snprintf(portStr, sizeof(portStr), "%hu", (ushort)port);
    if (getaddrinfo("localhost", portStr, NULL, &ainfo) != 0)
        systemError(2, "failed to retrieve info about localhost", false);

    shared->sockFd = socket(ainfo->ai_family, SOCK_STREAM, IPPROTO_TCP);
    if (shared->sockFd < 0)
        systemError(3, "failed to create a TCP socket", false);

    res = bind(shared->sockFd, ainfo->ai_addr, ainfo->ai_addrlen);
    if (res != 0)
        systemError(5, "failed to bind socket to local port", true);

    res = ::listen(shared->sockFd, backlog);
    if (res != 0)
        systemError(6, "failed to set socket to listen state", true);

    freeaddrinfo(ainfo);

}

Do you see anything that i overlooked?

Upvotes: 1

Views: 2580

Answers (1)

Youda008
Youda008

Reputation: 1959

Ok, so thanks to CristiFati i found the problem. The function getaddrinfo("localhost", portStr, NULL, &ainfo) used that way was returning an IPv6 address. While accept was getting sockaddr_in, which is a struct for IPv4 address.

It could be probably solved more ways, for example

  • using sockaddr_in6 for IPv6 communication
  • telling getaddrinfo to to search only IPv4 results with 3rd argument
  • picking up next result in the linked list returned by getaddrinfo

But i chose to manualy init the socket for IPv4 protocol this way:

    struct sockaddr_in myAddr;

    memset(&myAddr, 0, sizeof(myAddr));
    myAddr.sin_family = AF_INET;
    myAddr.sin_port   = htons((ushort)port);

    shared->sockFd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (shared->sockFd < 0)
        systemError(3, "failed to create a TCP socket", false);

    res = bind(shared->sockFd, (struct sockaddr *)&myAddr, sizeof(myAddr));
    if (res != 0)
        systemError(5, "failed to bind socket to local port", true);

Since that, everything works.

Upvotes: 1

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