Question

（也许我用烦人的细节来解释这个问题，tl; dr版本在底部）

我一直在尝试使用JNA在Java中创建一个简单的Winsock测试应用程序。我调用的第一个函数是WSAStartup（），使用以下代码：

public interface Ws2_32 extends Library {
    Ws2_32 INSTANCE = (Ws2_32) Native.loadLibrary("ws2_32", Ws2_32.class);

    int WSAStartup(short version, LPWSADATA lpwsaData);

}

public static void main(String[] args){
    LPWSADATA   lpwsaData = new LPWSADATA();
    short       version = 2;
    int         result = Ws2_32.INSTANCE.WSAStartup(version,lpwsaData);

    System.out.println("WSAStartup() returned: " + result);

    if((resultado = Ws2_32.INSTANCE.WSAStartup(version,lpwsaData)) == 0){
        System.out.println("LPWSADATA struct:");
        System.out.println("wVersion: " + lpwsaData.wVersion);
        System.out.println("wHighVersion: " + lpwsaData.wHighVersion);

        System.out.print("szDescription: ");
        for(byte b : lpwsaData.szDescription){
            System.out.print((char) b);
        }
        System.out.print("\n");

        System.out.print("szSystemStatus: ");
        for(byte b : lpwsaData.szSystemStatus){
            System.out.print((char) b);
        }
        System.out.print("\n");

        System.out.println("iMaxSockets: " + lpwsaData.iMaxSockets);
        System.out.println("iMaxUdpDg: " + lpwsaData.iMaxUdpDg");
    }
}

这样可行，我得到以下值：

wVersion：2

wHighVersion：514

szDescription：WinSock 2.0

szSystemStatus：正在运行

iMaxSockets：0

iMaxUdpDg：0

WSAStartup（）成功返回后，我尝试调用WSAEnumProtocols（）但是我收到以下错误：

线程“main”中的异常java.lang.UnsatisfiedLinkError：查找函数'WSAEnumProtocols'时出错：找不到指定的过程。

然后我使用Dependency Walker打开了ws2_32.dll，发现没有该名称的函数。我只找到了3个名字相似的名字：WSAEnumProtocolsA（），WSAEnumProtocolsW（）和WSCEnumProtocols（）。我将使用WSAEnumProtocolsA（）作为示例，但我使用了下一个过程，并使用了所有3个并获得了相同的结果：

首先我调用了WSAStartup（）并且没有返回任何错误。根据WSAEnumProtocols的MSDN定义，对函数的第一次调用应该是这样的： WSAEnumProtocols（null，wsaprotocol_info，lpdwBufferLength）第一个参数为null，第二个参数是指向WSAPROTOCOL_INFO结构的指针，第三个参数是缓冲区的长度。如果该长度为零，则该函数应返回-1（SOCKET_ERROR）并且对WSAGetLastError（）的调用应返回WSAENOBUFS，这意味着缓冲区不足以包含WSAEnumProtocols（）返回的信息，并应设置变量lpdwBufferLength具有可传递给WSAEnumProtocols的最小缓冲区大小以检索所有请求的信息。我不能让这个工作。 WSAEnumProtocols（）返回-1，但lpdwBufferLength的值未更改，WSAGetLastError（）返回0而不是10055（WSAENOBUFS）

我还尝试使用WSASetLastError（）并将其设置为其他一些错误代码然后调用WSAGetLastError（），但它总是返回0.。

TL;博士 我无法使用WSAEnumProtocols（null，wsaprotocol_info，lpdwBufferLength）。 WSAEnumProtocols（）返回-1，但lpdwBufferLength的值未更改，WSAGetLastError（）返回0而不是10055（WSAENOBUFS）

更新：

这是我用来声明Winsock函数的接口

public interface Ws2_32 extends Library {
    Ws2_32 INSTANCE = (Ws2_32) Native.loadLibrary("ws2_32", Ws2_32.class);

    int WSAStartup(short version, LPWSADATA lpwsaData);
    int WSAEnumProtocolsW(int[] lpiProtocols, WSAPROTOCOL_INFO lpProtocolBuffer, int lpdwBufferLength);
    int WSACleanup();
    int WSAGetLastError();
    int WSASetLastError(int iError);
}

这是我调用函数的代码：

public class TestWSAEnumProtocolsA {

    public void start(){

        WSAPROTOCOL_INFO        wsaprotocol_info = new WSAPROTOCOL_INFO();
        LPWSADATA               lpwsaData = new LPWSADATA();
        int                     lpdwBufferLength = -2;
        int                     result = 0;
        short                   version = 514;

        if((result = Ws2_32.INSTANCE.WSAStartup(version, lpwsaData)) != 0){
            System.out.println("Error #" + result + " at WSAStartup()");
            return;
        } else {
            System.out.println("WSAStartup() finished correctly.");

            if((result = Ws2_32.INSTANCE.WSAEnumProtocols(null, wsaprotocol_info, lpdwBufferLength)) == -1){
                System.out.println("WSAEnumProtocolsW() returned: " + result);
                System.out.println("lpdwBufferLength is: " + lpdwBufferLength);

                System.out.println("WSAGetLastError() returned: " + Ws2_32.INSTANCE.WSAGetLastError());

                System.out.println("Now I'm setting it to 10004");
                Ws2_32.INSTANCE.WSASetLastError(10004);
                System.out.println("WSAGetLastError() returned: " + Ws2_32.INSTANCE.WSAGetLastError());
            }
        }
    }
}

该代码产生以下输出：

WSAStartup（）正确完成。

WSAEnumProtocolsW（）返回：-1

lpdwBufferLength是：-2

WSAGetLastError（）返回：0

现在我将其设置为10004

WSAGetLastError（）返回：0

这就是我在调用这些函数时定义的结构：

public class WinSock2_structs {

    public static class LPWSADATA extends Structure{

        public short            wVersion;
        public short            wHighVersion;
        public byte             szDescription[] = new byte[256+1];
        public byte             szSystemStatus[] = new byte[128+1];
        public short            iMaxSockets;
        public short            iMaxUdpDg;
        public char             lpVendorInfo;       
}

    public static class WSAPROTOCOLCHAIN extends Structure{

        public int   ChainLen;
        public int   ChainEntries[] = new int[7];
    }

    public static class GUID extends Structure{

        public int      Data1;
        public short    Data2;
        public short    Data3;
        public short    Data4;
        public byte     Data5[] = new byte[8];

    }

    public static class WSAPROTOCOL_INFO extends Structure{

        public int                  dwServiceFlags1;
        public int                  dwServiceFlags2;
        public int                  dwServiceFlags3;
        public int                  dwServiceFlags4;
        public int                  dwProviderFlags;
        public GUID                 ProviderId;
        public int                  dwCatalogEntryId;
        public WSAPROTOCOLCHAIN     ProtocolChain;
        public int                  iVersion;
        public int                  iAddressFamily;
        public int                  iMaxSockAddr;
        public int                  iMinSockAddr;
        public int                  iSocketType;
        public int                  iProtocol;
        public int                  iProtocolMaxOffset;
        public int                  iNetworkByteOrder;
        public int                  iSecurityScheme;
        public int                  dwMessageSize;
        public int                  dwProviderReserved;
        public char                 szProtocol[] = new char[256];

    }
}

Answer 1

您正在调用WSAStartup()两次，这需要您两次调用WSACleanup()才能正确卸载WinSock。你应该只调用WSAStartup()一次。

szProtocol结构的WSAPROTOCOL_INFO成员是TCHAR个元素的数组。 TCHAR映射到char或wchar_t，具体取决于调用的应用是针对ANSI / MBCS还是UNICODE编译的。这就是ws2_32.dll中没有WSAEnumProtocols()函数的原因。而是有单独的WSAEnumProtocolsA()（对于Ansi）和WSAEnumProtocolsW()（对于Unicode）函数。由于Java使用Unicode字符串，因此您应该使用JNA代码WSAEnumProtocolsW()。 WSAStartup()不使用TCHAR，仅使用char，这就是为什么没有单独的WSAStartupA()和WSAStartupW()函数的原因。

如果您的JNA代码无法使WSAEnumProtocols()和WSAGetLastError()正常工作，则可能是您声明/使用它们错误，但您没有显示任何代码，所以没有人可以肯定地说为什么它不适合你。

更新：尝试这样的事情（我不使用JNA，所以这可能需要一些调整，但这会给你一般的想法）：

public interface Ws2_32 extends Library {

    // I don't know how to declare fixed size arrays in JNA,
    // so you will have to adjust these Structue declarations
    // as needed...

    public static class WSAData extends Structure {
        short wVersion;
        short wHighVersion;
        byte  szDescription[257];
        byte  szSystemStatus[129];
        short iMaxSockets;
        short iMaxUdpDg;
        String lpVendorInfo;
    };

    public static class WSAPROTOCOLCHAIN extends Structure {
        int ChainLen;
        int ChainEntries[7];
    };

    public static class WSAPROTOCOL_INFOW extends Structure {
        int dwServiceFlags1;
        int dwServiceFlags2;
        int dwServiceFlags3;
        int dwServiceFlags4;
        int dwProviderFlags;
        GUID ProviderId;
        int dwCatalogEntryId;
        WSAPROTOCOLCHAIN ProtocolChain;
        int iVersion;
        int iAddressFamily;
        int iMaxSockAddr;
        int iMinSockAddr;
        int iSocketType;
        int iProtocol;
        int iProtocolMaxOffset;
        int iNetworkByteOrder;
        int iSecurityScheme;
        int dwMessageSize;
        int dwProviderReserved;
        char szProtocol[256];
    };

    Ws2_32 INSTANCE = (Ws2_32) Native.loadLibrary("ws2_32", Ws2_32.class);

    int WSAStartup(short version, WSADATA lpwsaData);
    int WSAEnumProtocolsW(int[] lpiProtocols, WSAPROTOCOL_INFOW[] lpProtocolBuffer, IntByReference lpdwBufferLength);
    int WSACleanup();
    int WSAGetLastError();
    int WSASetLastError(int iError);
}

public static void main(String[] args){
    WSADATA     wsaData = new WSADATA();
    short       version = 2;
    int         result = Ws2_32.INSTANCE.WSAStartup(version, wsaData);

    System.out.println("WSAStartup() returned: " + result);

    if(result == 0){
        System.out.println("WSADATA struct:");
        System.out.println("wVersion: " + wsaData.wVersion);
        System.out.println("wHighVersion: " + wsaData.wHighVersion);

        System.out.print("szDescription: ");
        for(byte b : wsaData.szDescription){
            System.out.print((char) b);
        }
        System.out.print("\n");

        System.out.print("szSystemStatus: ");
        for(byte b : wsaData.szSystemStatus){
            System.out.print((char) b);
        }
        System.out.print("\n");

        System.out.println("iMaxSockets: " + wsaData.iMaxSockets);
        System.out.println("iMaxUdpDg: " + wsaData.iMaxUdpDg");
    }
}

public class TestWSAEnumProtocolsA {

    public void start(){

        WSAPROTOCOL_INFOW[]     wsaprotocol_info = new WSAPROTOCOL_INFOW[1];
        WSADATA                 wsaData = new WSADATA();
        IntByReference          dwBufferLength = new IntByReference(628); // sizeof WSAPROTOCOL_INFOW, in bytes
        int                     result = 0;
        short                   version = 2;

        if((result = Ws2_32.INSTANCE.WSAStartup(version, wsaData)) != 0){
            System.out.println("Error #" + result + " at WSAStartup()");
            return;
        }

        System.out.println("WSAStartup() finished correctly.");

        if((result = Ws2_32.INSTANCE.WSAEnumProtocolsW(null, wsaprotocol_info, dwBufferLength)) == -1){
            System.out.println("WSAEnumProtocolsW() returned: " + result);
            System.out.println("dwBufferLength is: " + dwBufferLength.getValue());
            System.out.println("WSAGetLastError() returned: " + Ws2_32.INSTANCE.WSAGetLastError());
        }
    }
}

Winsock2＆amp; JNA，无法让WSAEnumProtocols（）正常工作

1 个答案: