php curl登录，但有些页面返回移动到此处的对象

此登录可以正常工作：

function login($url,$data)
{
    $fp = fopen("cookie.txt", "w");
    fclose($fp);
    $login = curl_init();
    curl_setopt($login, CURLOPT_COOKIEJAR, "cookie.txt");
    curl_setopt($login, CURLOPT_COOKIEFILE, "cookie.txt");
    curl_setopt($login, CURLOPT_TIMEOUT, 40000);
    curl_setopt($login, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($login, CURLOPT_URL, $url);
    curl_setopt($login, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
    curl_setopt($login, CURLOPT_FOLLOWLOCATION, TRUE);
    curl_setopt($login, CURLOPT_POST, TRUE);
    curl_setopt($login, CURLOPT_POSTFIELDS, $data);
    ob_start();
    return  curl_exec ($login);
    ob_end_clean();
    curl_close ($login);
    unset($login);  
}                  

但在某些页面上，这会返回移动到此处的对象

function grab_page($site)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
    curl_setopt($ch, CURLOPT_TIMEOUT, 40000);
    curl_setopt($ch, CURLOPT_COOKIEFILE, "cookie.txt");
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 0);
    curl_setopt($ch, CURLOPT_URL, $site);
    ob_start();
    return curl_exec ($ch);
    ob_end_clean();
    curl_close ($ch);
}

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我已经尝试了

CURLOPT\u FOLLOWLOCATION

，1但它返回登录页面

Remove$\u SERVER['HTTP\u USER\u AGENT']

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并输入登录后重定向的页面名称

对不起，我不太明白这会怎么做