C++ HTTP Winsock：在学校"Banned URL"，甚至是允许的网站

C++ HTTP Winsock: "Banned URL" at school, even websites that are permitted

本文关键字：网站 URL Winsock HTTP Banned 学校 C++      更新时间：2023-10-16

我对使用套接字相当陌生，正在做我的第一个项目之一;其中第一个我实际上完全打算在没有任何库的情况下完成。 我使用的是Windows 7，只使用WinAPI。

我正在学校部分研究它，在我的学校，他们有一个网络过滤器，我相信FortiGuard。 即使我尝试在尝试通过 Web 浏览器(例如 google.com(打开时允许的域中获取页面，我也会收到以下消息：

<!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>

(我试图打破一点(。

如您所见，它说URL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 请求来访问在 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什么吗？

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", &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;
}

和 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/1.0rn");
                /*
                //user agent header
                str_req.append("User-Agent: conley-client/");
                str_req.append(VERSION);
                str_req.append("rn");
                */
                //final newline
                str_req.append("rn");
    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", 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, "");
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);

谢谢你的时间！

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user-agent之类的标头，以向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。

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