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Izviniaus
Asked:2022-08-20 19:43:03 +0000 UTC2022-08-20 19:43:03 +0000 UTC

您如何提前知道来自服务器的响应的长度以及是否有必要？

  • 772

我在套接字上发出了一个 http GET 请求，但遇到了一个问题：我怎样才能提前知道来自服务器的响应的长度以及是否有必要？这是请求（响应）代码：

 bool SendHttpGETRequest(LPCSTR PTFWP, LPCSTR site)
{
    string get = "GET "s + PTFWP + " HTTP/1.1\r\nHost: " + site + "\r\nConnection: close\r\n\r\n";

    if (send(servSock, get.c_str(), get.size(), 0) <= 0) {
        result = "Error\0";
        return false;
    }
    
    char* resHeaders = new char[310];

    if (recv(servSock, resHeaders, 310, 0) < 0) {
        result = "Error!\0";
        return false;
    }
    result = resHeaders;

    result = result.substr(result.find("Content-Length:") + 15);
    result = result.substr(0, result.find_first_of("\r\n"));

    int bufSize = stoi(result);
    delete resHeaders;
    resHeaders = new char[bufSize + 1];

    int readOfBytes = 0;
    int AllSize = 0;
    result = "";
    while (((readOfBytes = recv(servSock, resHeaders, bufSize, 0)) > 0) && ((AllSize+=readOfBytes)<= bufSize)) {
        result += resHeaders;
    }
    result[bufSize] = '\0';
    if ((readOfBytes < 0) && result.empty())
        return false;
    return true;
}
c++ winapi

1 个回答

  1. Best Answer

    将作者的答案从问题的正文中移开

    以下代码可以正常工作（我找到了一种接受服务器响应的方法）：

    bool CheckHTTPHeaders(string headers) {
    if (headers.empty())
        return false;
    
    string oneHead = headers.substr(0, headers.find_first_of("\r\n"));
    headers = headers.substr(oneHead.size()+1);
    if (oneHead != "HTTP/1.1 200 OK")
        return false;
    try
    {
        headers = headers.substr(headers.find("Content-Length:")+15);
        oneHead = headers.substr(0, headers.find("\r\n"));
        contentLength = stoi(oneHead);
        return true;
    }
    catch (...)
    {
        return false;
    }
}
bool SendHttpGETRequest(LPCSTR PTFWP, LPCSTR site)
{
    string get = "GET "s + PTFWP + " HTTP/1.1\r\nHost: " + site + "\r\nConnection: close\r\n\r\n";

    if (send(servSock, get.c_str(), get.size(), 0) <= 0) {
        result = "Error\0";
        return false;
    }
    
    char* res = new char[1024];
    int AllReadBytes = 0;
    if ((AllReadBytes = recv(servSock, res, 1024, 0)) < 0) {
        result = "Internet error\0";
        return false;
    }

    result = res;
    string headers = result.substr(0, result.find("\r\n\r\n"));
    result = result.substr(result.find("\r\n\r\n"));
    

    if (!CheckHTTPHeaders(headers)) {
        result = "SERVER SEND ERROR HEADER!\0";
        return false;
    }
    
    if (AllReadBytes < contentLength) {
        delete res;
        res = new char[contentLength];
        int ReadBytes;
        if ((ReadBytes = recv(servSock, res, contentLength, 0)) < 0) {
            result = "ERROR CONTENT!\0";
            return false;
        }
        AllReadBytes += ReadBytes;
        if (AllReadBytes < contentLength) {
            return false;
        }
        res[ReadBytes] = '\0';
        result += res;
        delete res;
    }

    return true;
}
    • 2

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