Winsock Error Codes

This section lists the error codes returned by Winsock functions. Understanding these errors is crucial for diagnosing and resolving network communication issues.

Code	Name	Description
WSAEINTR	WSAEINTR	A blocked Windows Sockets 1.1 call was canceled by an alarm or an interrupt.
WSAEBADF	WSAEBADF	A Windows Sockets specific error. This condition is normally detected by the sending code.
WSAEACCES	WSAEACCES	Permission denied.
WSAEFAULT	WSAEFAULT	Bad address. The system cannot access the specified address.
WSAEINVAL	WSAEINVAL	Invalid argument. Some invalid argument was encountered.
WSAEMFILE	WSAEMFILE	Too many open files.
WSAEWOULDBLOCK	WSAEWOULDBLOCK	Operation would block.
WSAEINPROGRESS	WSAEINPROGRESS	A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.
WSAEALREADY	WSAEALREADY	Operation already in progress.
WSAENOTSOCK	WSAENOTSOCK	An operation was attempted on something that is not a socket.
WSAEDESTADDRREQ	WSAEDESTADDRREQ	Destination address required.
WSAEMSGSZ	WSAEMSGSZ	Message too long.
WSAEPFNOSUPPORT	WSAEPFNOSUPPORT	Protocol family not supported.
WSAEOPNOTSUPP	WSAEOPNOTSUPP	Operation not supported.
WSAESHUTDOWN	WSAESHUTDOWN	Cannot send after transport endpoint shutdown.
WSAETOOMANYREFS	WSAETOOMANYREFS	Too many references.
WSAETIMEDOUT	WSAETIMEDOUT	Connection timed out.
WSAECONNREFUSED	WSAECONNREFUSED	Connection refused.
WSAELOOP	WSAELOOP	Too many levels of symbolic link.
WSAENAMETOOLONG	WSAENAMETOOLONG	File name too long.
WSAEHOST_NOT_FOUND	WSAEHOST_NOT_FOUND	Host not found.
WSAETRY_AGAIN	WSAETRY_AGAIN	Non-recoverable error.
WSAENO_RECOVERY	WSAENO_RECOVERY	Non-recoverable error.
WSAENOT_FOUND	WSAENOT_FOUND	Authoritative answer: host not found.
WSAENOT_RECOVERABLE	WSAENOT_RECOVERABLE	Entity returned is not a recoverable error.
WSAECONNABORTED	WSAECONNABORTED	Software caused connection abort.
WSAECONNRESET	WSAECONNRESET	Connection reset by peer.
WSAENOTCONN	WSAENOTCONN	Socket is not connected.
WSAESHUTDOWN	WSAESHUTDOWN	Cannot send after transport endpoint shutdown.
WSAETOOMANYREFS	WSAETOOMANYREFS	Too many references.
WSAETIMEDOUT	WSAETIMEDOUT	Connection timed out.
WSAECONNREFUSED	WSAECONNREFUSED	Connection refused.
WSAEHOST_DOWN	WSAEHOST_DOWN	Host is down.
WSAEPROCLIM	WSAEPROCLIM	Too many processes.
WSAEUSERS	WSAEUSERS	Too many users.
WSAEDQUOT	WSAEDQUOT	Disk quota exceeded.
WSAESTALE	WSAESTALE	Stale file handle reference.
WSAEREMOTE	WSAEREMOTE	Object is remote.
WSASYSNOTREADY	WSASYSNOTREADY	The network subsystem is unavailable.
WSAVERNOTSUPPORTED	WSAVERNOTSUPPORTED	The requested Windows Sockets version of the implementation is not supported.
WSANOTINITIALIZED	WSANOTINITIALIZED	Successful WSAStartup not yet performed.
WSAEDISCON	WSAEDISCON	A connection was forcibly terminated.
WSAENOMORE	WSAENOMORE	No more data is available.
WSAECANCELLED	WSAECANCELLED	Overlapped operation cancelled.
WSAERECEIVED_MORE_DATA	WSAERECEIVED_MORE_DATA	More data is available.
WSAESOCKTNOSUPPORT	WSAESOCKTNOSUPPORT	The specified socket type is not supported.

Understanding Winsock Errors

Winsock (Windows Sockets API) is the interface for network programming on Windows. When network operations fail, Winsock functions return specific error codes. These codes help developers identify the root cause of network problems, such as:

Network connectivity issues (e.g., WSAECONNREFUSED, WSAETIMEDOUT)
Address or name resolution problems (e.g., WSAEHOST_NOT_FOUND)
Protocol or socket configuration errors (e.g., WSAEPFNOSUPPORT, WSAENOTSOCK)
Resource limitations (e.g., WSAEMFILE, WSAEPROCLIM)

Common Error Handling Patterns

When calling Winsock functions, always check the return value. If an error occurs, you can use WSAGetLastError() to retrieve the specific error code and then consult this reference to understand and handle the error appropriately. A typical pattern looks like this:


int result = send(socket, buffer, length, flags);
if (result == SOCKET_ERROR) {
    int errorCode = WSAGetLastError();
    switch (errorCode) {
        case WSAEWOULDBLOCK:
            // Handle non-blocking send buffer full
            printf("Send would block.\n");
            break;
        case WSAECONNRESET:
            // Handle connection reset
            printf("Connection reset by peer.\n");
            break;
        default:
            // Handle other errors
            printf("Send failed with error: %d\n", errorCode);
            break;
    }
} else {
    // Send successful
    printf("Sent %d bytes.\n", result);
}

Remember to properly initialize Winsock using WSAStartup() before making any Winsock calls and clean up with WSACleanup() when your application is finished.

Windows API Reference

Winsock Error Codes

Understanding Winsock Errors

Common Error Handling Patterns