套接字在send（）上失去连接

Question

编辑：向下滚动以查看更新后的代码。

我想用C语言为Minecraft打造一个假玩家。

My Minecraft服务器（bukkit）正在侦听端口25565，在我的本地IP 192.168.1.141上

当我启动我的应用程序时，（当它通过套接字发送数据时）bukkit服务器说：“192.168.1.141:xxxxx丢失了连接”，并且

我的申请告诉我：

socked created
socked connected
to send data = (smilie)kekos91;192.168.1.141:25565
to send length = 27
send !
response data = (a strange symbol)
response length = 1
socket disconnected

这可能是因为char-set？ 有人知道为什么吗？这是我的代码：

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <winsock2.h>

int main()
{
    char pseudo[] = "kekos91;192.168.1.141:25565";
    int pseudoLen = strlen(pseudo);

    char *packet = NULL;
    packet = (char*)malloc(3 + ((pseudoLen)*sizeof(char)*2));
    if(packet == NULL)
    {
        return -1;
    }
    memset(packet, '\0', sizeof(packet));
    packet[0] = (char)0x02;
    strcat(packet, pseudo);
    int pLenght = strlen(packet);

    char handshake[200];

    HANDLE hConsole;
    WSADATA wsaData;
    int iResult = 0;

    SOCKET serverSocket;
    sockaddr_in serverInfos;

    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != NO_ERROR) {
        printf("WSAStartup() failed with error: %d\n", iResult);
        return -1;
    }

    serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (serverSocket == INVALID_SOCKET) {
        printf("socket function failed with error: %i\n", WSAGetLastError());
        WSACleanup();
        return -1;
    }
    printf("socket created\n");

    serverInfos.sin_family = AF_INET;
    serverInfos.sin_addr.s_addr = inet_addr("192.168.1.141");
    serverInfos.sin_port = htons(25565);

    iResult = connect(serverSocket, (SOCKADDR *)&serverInfos, sizeof(serverInfos));
    if (iResult == SOCKET_ERROR)
    {
        printf("connect function failed with error: %i\n", WSAGetLastError());
        iResult = closesocket(serverSocket);
        if (iResult == SOCKET_ERROR)
        {
           printf("closesocket function failed with error: %i\n", WSAGetLastError());
        }
        WSACleanup();
        return -1;
    }
    printf("socket connected\n");



    printf("to send data = %s\n", packet);
    printf("to send length = %i\n", pseudoLen);
    Sleep(500); // after this point, the connection is loose :(
    if(send(serverSocket, (char*)packet , pLenght, 0) == SOCKET_ERROR)
    {
        printf("send function failed with error: %i\n", WSAGetLastError());
        iResult = closesocket(serverSocket);
        if (iResult == SOCKET_ERROR)
        {
           printf("closesocket function failed with error: %i\n", WSAGetLastError());
        }
        WSACleanup();
        return -1;
    }
    free(packet);

    printf("send !\n");




    if(recv(serverSocket, (char*)&handshake, 200, 0) == SOCKET_ERROR)
    {
        printf("recv function failed with error: %i\n", WSAGetLastError());
        iResult = closesocket(serverSocket);
        if (iResult == SOCKET_ERROR)
        {
           printf("closesocket function failed with error: %i\n", WSAGetLastError());
        }
        WSACleanup();
        return -1;
    }

    printf("response data = %s\n", handshake);      
    printf("response length = %i\n", strlen(handshake)); 

    iResult = closesocket(serverSocket);
    if (iResult == SOCKET_ERROR) {
        printf("closesocket function failed with error %i\n", WSAGetLastError());
        WSACleanup();
        return -1;
    }
    printf("socket disconnected.\n");

    WSACleanup();
    Sleep(5000);
    return 0;
}

提前致谢，请原谅我糟糕的英语：）

更新：

感谢建设性的评论，现在一切都很完美。 以下是工作代码，供您查看旧代码的内容。

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <winsock2.h>

int main()
{
    int iSocketResult = 0; // it will retrieve sockets return functions, like send / recv / errors

    wchar_t wcPseudo[] = L"kekos91;192.168.1.141:25565";
    int iPseudoLen = wcslen(wcPseudo);

    char *pPacket = NULL;
    pPacket = (char*)malloc(3 + ((iPseudoLen)*sizeof(char)*2));
    if(pPacket == NULL)
    {
        return -1;
    }
    pPacket[0] = 0x02;


    *(short*)( pPacket + 1 ) = htons( iPseudoLen );
    memcpy( pPacket + 3, wcPseudo, iPseudoLen * sizeof( wchar_t ));

    int iPacketLen = 3 + iPseudoLen*sizeof(wchar_t) ;    

    char *handshake  = NULL;
    handshake = (char*)malloc(sizeof(char)*200);
    if(handshake == NULL)
    {
        return -1;
    }


    HANDLE hConsole;
    WSADATA wsaData;        

    SOCKET serverSocket;
    sockaddr_in serverInfos;

    iSocketResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iSocketResult != NO_ERROR) {
        printf("WSAStartup() failed with error: %d\n", iSocketResult);
        return -1;
    }

    serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (serverSocket == INVALID_SOCKET) {
        printf("socket function failed with error: %i\n", WSAGetLastError());
        WSACleanup();
        return -1;
    }

    printf("socket created\n");

    serverInfos.sin_family = AF_INET;
    serverInfos.sin_addr.s_addr = inet_addr("192.168.1.141");
    serverInfos.sin_port = htons(25565);

    iSocketResult = connect(serverSocket, (SOCKADDR *)&serverInfos, sizeof(serverInfos));
    if (iSocketResult == SOCKET_ERROR)
    {
        printf("connect function failed with error: %i\n", WSAGetLastError());
        iSocketResult = closesocket(serverSocket);
        if (iSocketResult == SOCKET_ERROR)
        {
           printf("closesocket function failed with error: %i\n", WSAGetLastError());
        }
        WSACleanup();
        return -1;
    }
    printf("socket connected\n\n");

    printf("to send protocol = %#1.2x \nlenght = %i\n", pPacket[0], iPseudoLen);

    iSocketResult = send(serverSocket, pPacket , iPacketLen, 0);
    if(iSocketResult == SOCKET_ERROR)
    {
        printf("send function failed with error: %i\n", WSAGetLastError());
        iSocketResult = closesocket(serverSocket);
        if (iSocketResult == SOCKET_ERROR)
        {
           printf("closesocket function failed with error: %i\n", WSAGetLastError());
        }
        WSACleanup();
        return -1;
    }
    free(pPacket);

    printf("send %i (bytes) !\n\n",iSocketResult);


    iSocketResult = recv(serverSocket, handshake, 50, 0);
    if( iSocketResult == SOCKET_ERROR)
    {
        printf("recv function failed with error: %i\n", WSAGetLastError());
        iSocketResult = closesocket(serverSocket);
        if (iSocketResult == SOCKET_ERROR)
        {
           printf("closesocket function failed with error: %i\n", WSAGetLastError());
        }
        WSACleanup();
        return -1;
    }

    printf("response protocol = %#1.2x\nresponse lenght = %i (bytes)\n\n", handshake[0], iSocketResult);
    free(handshake);    


    iSocketResult = closesocket(serverSocket);
    if (iSocketResult == SOCKET_ERROR)
    {
        printf("closesocket function failed with error %i\n", WSAGetLastError());
        WSACleanup();
        return -1;
    }
    printf("socket disconnected.\n");

    WSACleanup();
    Sleep(7000);
    return 0;
}

输出控制台现在打印：

socket created
socket connected

to send protocol = 0x02 
lenght = 27
send 57 (bytes) !

response protocol = 0x02
response lenght = 37 (bytes)

socket disconnected.

谢谢大家！

Answer 1

一般来说，你所做的似乎是正确的。我想，当您的测试代码关闭自己的套接字时，服务器发生“连接丢失”消息。但是，您似乎没有正确处理string data type。该字符串需要以Unicode格式发送，并且您似乎将其作为单字节字符发送。此外，字符串需要以表示为2字节整数的长度开头。

也可以使用wchar_t（或您喜欢的宽字符数据类型）将握手字符串指定如下。并在文字上使用L来指定宽字符串。实际的发送长度（以字节为单位）需要确保将字符串长度乘以2.

wchar_t pseudo [] = L“kekos91; 192.168.1.141：25565”;    int pseudoLen = wcslen（伪）;

然后，同样地，使用宽字符串函数来复制字符串（strcat将不起作用）。

要将字符串长度放在0x02协议代码之后的两个字节中，您可以这样做：

*((short*)( packet + 1 ) = htons( pseudolLen );

要将字符串复制到数据包中，也许这样（我正在编写此文件而不编译：

memcpy( packet + 3, pseudo, pseudoLen * sizeof( wchar_t ));

实际发送长度（以字节为单位）为：3 + pseudoLen * sizeof( wchar_t )

打印生成的响应时，可能会出现这样的内容：

printf( "Protocol response: %02x\n", handshake[0] );

然后提取字符串（协议字节后面的两个字节应该是连接散列字符串的长度（按网络字节顺序）。所以你需要使用ntohs来提取它。然后以下N个宽字符代表哈希值。

编写完所有内容后，在我看来，您可能希望寻找一个库来处理所有协议。我没看过，但似乎有一些可用于C的Minecraft相关套接字库。只是一个疯狂的猜测。 修改第二个想法，这取决于您的目标。如果您只是想尽快建立一个客户端，那么寻找一个库肯定是有意义的。但是，如果您想要了解协议，网络编程等的详细信息，那么在您开始的级别编写它是一个好主意，并且会很有趣，因为您可以制作显示实际结果的增量步骤经常。

另一件事。分配内存后memset可能没有按预期执行。假设一个32位架构，sizeof( packet )将为4（它是一个4字节指针）。但是，由于您将使用数据填充数据包，因此不需要memset。