c++ - 使用C/C++(套接字)连接到Gmail SMTP服务器

Question

我尝试用纯套接字连接到Google SMTP服务器(“smtp.gmail.com”)。
我创建了一个套接字，当我读取数据仅给我“54”或“52”或“53”或“54”时连接。

    sockaddr_in service;
    WSADATA wsaData;

    struct hostent* remoteHost;

    int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (result != NO_ERROR) {
        std::cout << 1;
        return EXIT_FAILURE;
    }

    sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (sock == INVALID_SOCKET) {
        WSACleanup;
        return EXIT_FAILURE;
    }

    remoteHost = gethostbyname(SMTP_HOST);

    memset(&service, 0, sizeof(service));
    service.sin_family = AF_INET;
    service.sin_addr.s_addr = *(u_long*)remoteHost->h_addr_list[0];
    service.sin_port = htons(25);


    if (connect(sock, (SOCKADDR*)&service, sizeof(service)) == SOCKET_ERROR) {
        WSACleanup;
        return EXIT_FAILURE;
    }

    char senddata[] = "STARTTLS";

    read_socket();
    send(sock, EHLO, strlen(EHLO), 0);
    read_socket();
    send(sock, senddata, strlen(senddata), 0);

    std::cout << 0;
    return EXIT_SUCCESS;

我的read_socket函数

void read_socket() {
    int bytesRecv = recv(sock, recvbuf, BUFSIZ, 0);

    if (bytesRecv == 0 || bytesRecv == WSAECONNRESET) {
        std::cout << "Connection closed"<<std::endl;
        return;
    }

    std::cout << bytesRecv << std::endl;
}

编辑:添加read_socket函数。

Answer 1

recv将缓冲区作为参数并返回接收到的字节数，代码中的bytesRecv是接收到的字节数(54字节)而不是字节，以查找Google回答的问题，您需要显示recvbuf

std::cout << recvbuf << std::endl;