C++ 客户端套接字仅接收消息的第一个字母

Question

这几天我一直被一个问题困扰。我需要用 C++ 设计一个音乐流应用程序。但是，我发现很难发送从目录中读取文件时获得的文件名。文件名是“sample.wav”和“sample1.wav”，但客户端每次只接收和输出字母S。尽管如果我手动发送从服务器分配给变量的字符串消息，客户端就会收到它。你能指出我正确的方向吗？

提前致谢。

服务器端

        sockaddr_in hint;
        hint.sin_family = AF_INET;
        hint.sin_port = htons(54000);

        hint.sin_addr.S_un.S_addr = INADDR_ANY;
        // for local ip: inet_pton

        bind(listening, (sockaddr*)&hint, sizeof(hint));

        // max number of open connections (SOMAXCONN)
        listen(listening, SOMAXCONN);

        // waiting for connection
        sockaddr_in client;
        int clientSize = sizeof(client);

        SOCKET clientSocket = accept(listening, (sockaddr*)&client, &clientSize);

        SOCKET* client_ptr = &clientSocket;
        char host[NI_MAXHOST];
        // client's remote name

        char service[NI_MAXSERV];
        // the port on which the client connects

        ZeroMemory(host, NI_MAXHOST);
        //ZeroMemory(service, NI_MAXHOST);
        // cleaning memory

        sockList.push_back(&clientSocket);

        if (getnameinfo((sockaddr*)&client, sizeof(client), host, NI_MAXHOST, service, NI_MAXSERV, 0) == 0)
        {
            for (int i = 0; i < 2; i++) {
                int postList = send(clientSocket, mainList.GetSongName(i).c_str(), mainList.GetSongName(i).size() + 1,0);
            }
        }
        else {

            inet_ntop(AF_INET, &client.sin_addr, host, NI_MAXHOST);
            cout << host << " connected on port " << ntohs(client.sin_port) << endl;
        }

        closesocket(listening);
 }

客户端:

string ipAddress = "127.0.0.1";
int port = 54000;

WSAData data;
WORD ver = MAKEWORD(2, 2);

int wsResult = WSAStartup(ver, &data);

if (wsResult != 0) {
    cerr << "Can't start Winsock, Err #:" << wsResult << endl;
    return 0;
}

SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);

if (sock == INVALID_SOCKET) {
    cerr << "Can't create socket. Err #:" << WSAGetLastError << endl;
    return 0;
}

sockaddr_in hint;
hint.sin_family = AF_INET;
hint.sin_port = htons(port);

inet_pton(AF_INET, ipAddress.c_str(), &hint.sin_addr);

//hint.sin_addr.S_un.S_addr = INADDR_ANY;

int connResult = connect(sock, (sockaddr*)&hint, sizeof(hint));

bind(sock, (sockaddr*)&hint, sizeof(hint));

if (connResult == SOCKET_ERROR) {
    cerr << "Can't connect to Server, Err #:" << WSAGetLastError() << endl;
    closesocket(sock);
    WSACleanup();
}

char buffer[4096];
string userInput;

ZeroMemory(buffer, 4096);

int msglen;
int numbytes = 0;

int welcomemsg = recv(sock, buffer, sizeof(buffer), 0);

cout << sizeof(buffer) << endl;
cout << "Server >>" << string(buffer, 0, welcomemsg) << endl;

do {
     welcomemsg = recv(sock, buffer, 4096, 0);

    if (welcomemsg > 0) {
        cout << "Server >>" << string(buffer, 0, welcomemsg) << endl;
    }
    else {
        cerr << "Client disconnected" << endl;
    }
} while (welcomemsg > 0);

songList 对象构造函数:

wchar_t* w_Path = (wchar_t*)malloc(strlen(filePath) * sizeof(wchar_t));

mbstowcs(w_Path, filePath, strlen(filePath) + 1);

HANDLE hFind;
WIN32_FIND_DATA data;

LPCWSTR m_Path = w_Path;

memset(&data, 0, sizeof(WIN32_FIND_DATA));

hFind = FindFirstFile(m_Path, &data);

if (hFind != INVALID_HANDLE_VALUE) {
    int i = 0;

    do {
        printf("\n %S", data.cFileName);
        songNames[i] = (char*)data.cFileName;
        i++;
    } while (FindNextFile(hFind, &data));
    FindClose(hFind);
}
else {
    cout << "No songs found in directory" << endl;
}

Answer 1

问题是您正在 Unicode 模式下工作，并且结构 WIN32_FIND_DATA 被 typedef 转换为 WIN32_FIND_DATAW，因此 songNames[ i] = (char*)data.cFileName; 将 wchar_t 字符的字符串重新解释为单字节字符。

从多字节角度来看，whar_t 字符的字符串看起来像一个以 null 结尾的 1 个字符的字符串。

作为快速修复方法，请将服务器项目模式更改为多字节(注意 - 代码中可能存在更多错误，因此可能需要进行更多修复才能使其正常工作)。

但更好的是，继续使用 Unicode 模式并调整代码以使用 wchar_t 字符而不是 char。这意味着将 char buffer[] 更改为 wchar_t buffer[] 并在必要时调整大小值。