linux c++ 实现http的get()函数

使用linux c++实现了http的get请求

传入参数：传入参数是要请求的url

传出参数：请求到的网页

为了方便说明，这里假定url = "http://search.360buy.com/Search?keyword=ŮЬ&page=67&ev=";

std::string chttpget::run(std::string url)

{

    string page;

    int sockfd, ret, i, h;

    struct sockaddr_in servaddr;

    char str[4096],buf[BUFSIZE];

    socklen_t len;

    fd_set t_set1;

    fd_set mask;

    struct timeval  tv;

 

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) 

    {

       printf("创建网络连接失败,本线程即将终止---socket error!\n");

       exit(0);

    };

 

 

    bzero(&servaddr, sizeof(servaddr));

    servaddr.sin_family = AF_INET;

    servaddr.sin_port = htons(PORT);

    //将域名转为ip地址

    struct hostent *host = gethostbyname(search.360buy.com);

    

    char* ipstr = (char *)inet_ntoa(*(struct in_addr *)(host->h_addr));

    if (inet_pton(AF_INET, ipstr, &servaddr.sin_addr) <= 0 )

    {

          printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");

          exit(0);

    };

    // 非阻塞connect

     int flags=fcntl(sockfd,F_GETFL,0);

     fcntl(sockfd,F_SETFL,flags|O_NONBLOCK);

     ret =  connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));   

     if (-1 == ret)

     {

       printf("与远端建立了连接\n");

      if(errno != EINPROGRESS)

     {

       perror("connect");

       close(sockfd);

     }

 

     FD_ZERO(&mask);

     FD_SET(sockfd,&mask);

     tv.tv_sec = 1;

     tv.tv_usec = 0;

    

     switch(select(sockfd+1,NULL,&mask,NULL,&tv))

     {

     

      case -1:

      close(sockfd);

      case 0:

      close(sockfd);

     

      default:

      int error=0;

      socklen_t len = sizeof(int);

      if(getsockopt(sockfd,SOL_SOCKET,SO_ERROR,&error,&len))

      {

         if(0 == error)

        {

        printf("has connect");

        }

      }

     }

     }else if(0==ret)

     {

      printf("has connect\n");

     }

    memset(str, 0, 4096);

     // http协议请求字符串，每一行的后面一定要加\n隔开    

      strcat(str,"GET /Search?keyword=ŮЬ&page=68&ev= HTTP/1.1\n");

      strcat(str, "Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, application/x-ms-application, application/x-ms-xbap, application/vnd.ms-xpsdocument, application/xaml+xml, */* \n");

      strcat(str, "Accept-Language: zh-cn\n");

      strcat(str,"User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; (R1 1.6); .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)\n");

     strcat(str,"Host:search.360buy.com\n");

      strcat(str,"Connection: Keep-Alive");

      strcat(str, "\r\n\r\n");

 ret = write(sockfd,str,strlen(str));

 

  if (ret < 0) 

  {

         printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));

         exit(0);

  }

  else

  {

     printf("消息发送成功，共发送了%d个字节！\n\n", ret);

  }

      FD_ZERO(&t_set1);

      FD_SET(sockfd, &t_set1);

      while(1)

      {

   //设置超时为1秒，如果1秒还没有反应直接返回

             tv.tv_sec= 1;

              tv.tv_usec= 0;

              h= 0;

              memset(buf, 0, sizeof(buf));

              h= select(sockfd +1, &t_set1, NULL, NULL, &tv);

              if (h == 0)

              {

              close(sockfd);

                  return page;

              }

              if (h < 0) {

                      close(sockfd);

                      printf("在读取数据报文时SELECT检测到异常，该异常导致线程终止！\n");

                      return "";

              };

               if (h > 0){

                      memset(buf, 0, sizeof(buf));

                      

                      i= read(sockfd, buf, sizeof(buf));

                      

                      if(i>0)

                      {

                      page = page + buf;

                      

                      }else

                      {

                      close(sockfd);

                      return page;

                      }

   

              }

      }

      close(sockfd);

      return page;

}

这样就完成了一个http请求。