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我对使用套接字还很陌生，并且正在从事我的第一个项目之一；第一个我实际上完全打算在没有任何库的情况下完成。我在 Windows 7 上，只使用 WinAPI。

我正在学校部分研究它，我相信在我的学校他们有一个网络过滤器，FortiGuard。即使我尝试通过网络浏览器（例如 google.com）打开允许的域中的页面，我也会返回以下消息：

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<style type="text/css">html,body{height:100%;padding:0;margin:0;}.oc{display:table;width:100%;height:100%;}.ic{display:table-cell;vertical-align:middle;height:100%;}div.msg{display:block;border:1px solid#30c;padding:0;width:500px;font-family:helvetica,sans-serif;margin:10px auto;}h1{font-weight:bold;color:#fff;font-size:14px;margin:0;padding:2px;text-align:center;background: #30c;}p{font-size:12px;margin:15px auto;width:75%;font-family:helvetica,sans-serif;text-align:left;}</style>
<title>The URL you requested has been blocked</title>
</head>
<body><div class="oc"><div class="ic"><div class="msg"><h1>The URL you requested has been blocked</h1><p>The page you have requested has been blocked, because the URL is banned.<br /><br />URL = invalid<br /></p></div></div></div></body>
</html>

（我试图打破这一点）。

如您所见，它说该 URL 已被禁止，我认为这是网络过滤器，因为这只发生在我在学校时

至少我相信我正在使用正确的标准 HTTP GET 请求到在 Web 浏览器上正常工作的网站，但我收到了这条消息。我对套接字请求做错了吗？

这是我的套接字代码：

我有一个基本的“socket_t”结构可以传递给我的所有函数。这是它的定义：

//custom socket structure
typedef struct
{
    //windows-specific
    struct sockaddr win_addr;
    u_long mode;
    SOCKET socket;//acutal SOCKET structure

    // General
    bool listening;//set to true if actively listening
    bool thread_terminate;//when boolean is set to true, listening thread terminates
    void (*error_callback) (int);
    http_response_t * response;
} socket_t;

对于连接：

//see socket_t definition in socket.h
//returns 0 on success, SOCKET_ERROR on WinSock failure, positive error code on DNS failure
int socket_connect(socket_t * sock, char * addr, int port)
{
    //bear in mind sock is the custom socket_t structure.  sock->socket is the actual SOCKET structure.
    //pardon the nomenclature.  rookie code.
    //TODO:  IPv6 support?

    //DNS lookup structures
    struct addrinfo *   res             = NULL;// Result of the getaddrinfo() call
    struct sockaddr *   sockaddr_v4     = NULL;// IPv4 sockaddr structure

    // So-called "hints" structure detailed in the getaddrinfo() MSDN page.
    // I guess it contains information for the DNS lookup.
    struct addrinfo hints;
    memset(&hints, 0, sizeof(hints));
    hints.ai_family     = AF_UNSPEC;
    hints.ai_socktype   = SOCK_STREAM;
    hints.ai_protocol   = IPPROTO_TCP;

    //Perform DNS lookup
    DWORD getaddrinfo_res = getaddrinfo(addr, "80\0", &hints, &res);//hardcode port number, for now
    if(getaddrinfo_res != 0) return getaddrinfo_res;

    //for each
    for(struct addrinfo * ptr = res; ptr != NULL; ptr = ptr->ai_next)
    {
        switch(ptr->ai_family)
        {
        case AF_INET:
            sockaddr_v4 = (struct sockaddr *) ptr->ai_addr;//set current address
            sock->win_addr = * sockaddr_v4;//set socket address
        }
    }

    //initialize actual SOCKET
    sock->socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);// TCP/IP, stream-oriented, and TCP rather than UDP; respectively
    if(sock->socket == INVALID_SOCKET) return SOCKET_ERROR;

    //actual connection
    int connect_res = connect(sock->socket, &(sock->win_addr), sizeof(sock->win_addr));
    if(connect_res == SOCKET_ERROR) return SOCKET_ERROR;
    return 0;
}

HTTP请求位：

// Execute an HTTP request.
// Param 1: socket_t object
// Param 2: resource locator not including site name.
int socket_httprequest(socket_t * sock, char * rl)
{
    std::string str_req = std::string("GET /");
                str_req.append(rl);
                str_req.append(" HTTP/1.0\r\n");

                /*
                //user agent header
                str_req.append("User-Agent: conley-client/");
                str_req.append(VERSION);
                str_req.append("\r\n");
                */

                //final newline
                str_req.append("\r\n");

    const char * z_req = str_req.c_str();
    return send(sock->socket, z_req, (int) strlen(z_req), 0);
}

它们都在主函数中调用，如下所示：

// Initialization
conley::init_sockets();
conley::init_http();

conley::socket_t * sock = conley::socket_alloc(err_callback);
int connect_res = conley::socket_connect(sock, "google.com\0", 80);
if(connect_res > 0) std::cout << "DNS ERR " << connect_res << std::endl;
if(connect_res < 0) std::cout << "CONNECT ERR " << WSAGetLastError() << std::endl;
if(connect_res == 0) std::cout << "Connected" << std::endl;

int httpreq_res = conley::socket_httprequest(sock, "\0");
if(httpreq_res != -1) std::cout << "HTTP request success: " << httpreq_res << " bytes sent" << std::endl;
else std::cout << "HTTP request failure: Error " << WSAGetLastError() << std::endl;

conley::socket_listen(sock);

感谢您的时间！

4

1 回答 1

1

错误可能不是由您的程序引起的，而是因为过滤器检测到请求不是由浏览器发送的。浏览器发送诸如用户代理之类的标头以向它们发送请求的服务器标识自己。我的建议是使用像Wireshark这样的工具来捕获浏览器生成的流量并尝试从您的应用程序中模仿它。

于 2013-11-27T15:13:50.767 回答