WINSocket编程发生HTTP GET请求，并接收服务器返回

最新推荐文章于 2024-04-16 18:06:47 发布

原创最新推荐文章于 2024-04-16 18:06:47 发布 · 275 阅读

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CC 4.0 BY-SA版权

本文介绍如何使用Winsock库在C++中实现一个简单的HTTP客户端。该客户端能够连接到指定的服务器，发送HTTP请求，并接收服务器响应。文章详细展示了从初始化Winsock到建立TCP连接、发送请求直至读取完整HTTP响应的全过程。

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首先要添加引用

#include "winsock2.h" //header
#pragma comment (lib, "ws2_32.lib") //lib

调用的代码：

BOOL HttpClient(std::string& rest) //用参数接收返回的字符数据
{
    std::string errMsg;//错误信息记录
    WSADATA wsaData;
    SOCKET sock;
    SOCKADDR_IN tcpaddr;
    hostent * remoteHost;
    char   host[] = {"192.168.1.1"};     //主机名就直接写了
    int   Ret,l;
    BOOL done;
    int   port = 80;
    int   chars = 0;
    char buffer[1024];

    if( (Ret = WSAStartup(MAKEWORD(1,1), &wsaData) ) != 0 )
    {
        errMsg+="WSAStartup failed with error "+Ret;
        return 1;
    }

    if( (remoteHost = gethostbyname(host)) == NULL )       //通过主机名获取地址
    {
        errMsg+="gethostbyname error!\n";
        return 1;
    }

    sock = socket (AF_INET, SOCK_STREAM, 0);

    tcpaddr.sin_family = AF_INET;
    tcpaddr.sin_port = htons( (unsigned short)port );
    tcpaddr.sin_addr.s_addr = *((unsigned long *)*remoteHost->h_addr_list); //转换地址

    if( connect(sock, (const sockaddr * )&tcpaddr, sizeof(tcpaddr)) )
    {
        errMsg+="connect error!";
        return 1;
    }
    //这里是要发送的http头部
    SendString(sock,"GET / HTTP/1.1\r\n");
    SendString(sock,"Host:192.168.1.1\r\n");
    SendString(sock,"Accept: */*\r\n");
    SendString(sock,"User-Agent: Mozilla/4.0");
    SendString(sock,"(compatible; MSIE 7.00; Windows 98)\r\n");
    SendString(sock,"Connection:Keep-Alive\r\n");
    SendString(sock,"\r\n");
    SendString(sock,"\r\n");//最后要加空行

    done = FALSE;
    //FILE * fp;
    //fp = fopen("1.txt","w");
    //打印并保存http响应的头部
    std::string str;
    while(!done)
    {
        l = recv(sock,buffer,1,0);//一个字节一个字节的接受HTTP头
        str+=*buffer;
        if(l<0)
            done=TRUE;
        switch(*buffer)
        {
        case '\r':
            break;
        case '\n'://判断HTTP头是否接受完毕
            if(chars==0)
                done = TRUE;
            chars=0;
            break;
        default:
            chars++;
            break;
        }
        printf("%c",str);
        //fputc(buffer[0],fp);
    }

    //接收正文部分
    int sum = 0;
    do
    {
        l = recv(sock,buffer,1024,0);
        if( l < 0 )
            break;
        sum += l;

        str.append(buffer,l);

        //*(buffer + l) = 0;
        //fputs(buffer,fp);

    } while( l > 0 );

    //这里输出正文部分大小，发现其实和响应消息头部的Content-length大小是一样的
    //这样就可以检查是否接受完毕
    printf("sum = %d\n",sum);

    closesocket(sock);

    if( WSACleanup() == SOCKET_ERROR )
    {
        errMsg+="WSACleanup failed with error "+WSAGetLastError();
    }
    rest=str;

    return 1;
}

void SendString(SOCKET sock,LPCSTR str)
{
    send(sock,str,strlen(str),0);
}