• $gurl 要下载的图片地址
• $rfurl 来路。如果目标图像做了防盗链设置，可以绕过。
• $filename 下载图片保存的文件名，相对路径，不要用realpath
• $gcookie 调整cookie 伪造的cookie
• $JumpCount 跳转计数
• $maxtime 最大次数

调用方法：

DownImageKeep(“http://www.baidu.com/img/baidu_jgylogo2.gif”,”http://baidu.com”,”a.gif”,”",0,10);

函数代码：

<?php
function    DownImageKeep($gurl,    $rfurl,    $filename,    $gcookie="",    $JumpCount=0,    $maxtime=30)
{
                $urlinfos    =    GetHostInfo($gurl);
                $ghost    =    trim($urlinfos['host']);
                if($ghost=='')
                {
                                return    FALSE;
                }
                $gquery    =    $urlinfos['query'];
                if($gcookie==""    &&    !empty($rfurl))
                {
                                $gcookie    =    RefurlCookie($rfurl);
                }
                $sessionQuery    =    "GET    $gquery    HTTP/1.1
";
                $sessionQuery    .=    "Host:    $ghost
";
                $sessionQuery    .=    "Referer:    $rfurl
";
                $sessionQuery    .=    "Accept:    */*
";
                $sessionQuery    .=    "User-Agent:    Mozilla/4.0    (compatible;    MSIE    5.00;    Windows    98)
";
                if($gcookie!=""    &&    !preg_match("/[
]/",    $gcookie))
                {
                                $sessionQuery    .=    $gcookie."
";
                }
                $sessionQuery    .=    "Connection:    Keep-Alive

";
                $errno    =    "";
                $errstr    =    "";
                $m_fp    =    fsockopen($ghost,    80,    $errno,    $errstr,10);
                fwrite($m_fp,$sessionQuery);
                $lnum    =    0;
                //获取详细应答头
                $m_httphead    =    Array();
                $httpstas    =    explode("    ",fgets($m_fp,256));
                $m_httphead["http-edition"]    =    trim($httpstas[0]);
                $m_httphead["http-state"]    =    trim($httpstas[1]);
                while(!feof($m_fp))
                {
                                $line    =    trim(fgets($m_fp,256));
                                if($line    ==    ""    ||    $lnum>100)
                                {
                                                break;
                                }
                                $hkey    =    "";
                                $hvalue    =    "";
                                $v    =    0;
                                for($i=0;    $i<strlen($line);    $i++)
                                {
                                                if($v==1)
                                                {
                                                                $hvalue    .=    $line[$i];
                                                }
                                                if($line[$i]==":")
                                                {
                                                                $v    =    1;
                                                }
                                                if($v==0)
                                                {
                                                                $hkey    .=    $line[$i];
                                                }
                                }
                                $hkey    =    trim($hkey);
                                if($hkey!="")
                                {
                                                $m_httphead[strtolower($hkey)]    =    trim($hvalue);
                                }
                }
                //分析返回记录
                if(preg_match("/^3/",    $m_httphead["http-state"]))
                {
                                if(isset($m_httphead["location"])    &&    $JumpCount<3)
                                {
                                                $JumpCount++;
                                                DownImageKeep($gurl,$rfurl,$filename,$gcookie,$JumpCount);
                                }
                                else
                                {
                                                return    FALSE;
                                }
                }
                if(!preg_match("/^2/",    $m_httphead["http-state"]))
                {
                                return    FALSE;
                }
                if(!isset($m_httphead))
                {
                                return    FALSE;
                }
                $contentLength    =    $m_httphead['content-length'];
                //保存文件
                $fp    =    fopen($filename,"w")    or    die("写入文件：{$filename}    失败！");
                $i=0;
                $okdata    =    "";
                $starttime    =    time();
                while(!feof($m_fp))
                {
                                $okdata    .=    fgetc($m_fp);
                                $i++;
                                //超时结束
                                if(time()-$starttime>$maxtime)
                                {
                                                break;
                                }
                                //到达指定大小结束
                                if($i    >=    $contentLength)
                                {
                                                break;
                                }
                }
                if($okdata!="")
                {
                                fwrite($fp,$okdata);
                }
                fclose($fp);
                if($okdata=="")
                {
                                @unlink($filename);
                                fclose($m_fp);
                                return    FALSE;
                }
                fclose($m_fp);
                return    TRUE;
}
/**
    *        获得某页面返回的Cookie信息
    *
    *    @access                public
    *    @param                    string        $gurl        调整地址
    *    @return                string
    */
function    RefurlCookie($gurl)
{
                global    $gcookie,$lastRfurl;
                $gurl    =    trim($gurl);
                if(!empty($gcookie)    &&    $lastRfurl==$gurl)
                {
                                return    $gcookie;
                }
                else
                {
                                $lastRfurl=$gurl;
                }
                if(trim($gurl)=='')
                {
                                return    '';
                }
                $urlinfos    =    GetHostInfo($gurl);
                $ghost    =    $urlinfos['host'];
                $gquery    =    $urlinfos['query'];
                $sessionQuery    =    "GET    $gquery    HTTP/1.1
";
                $sessionQuery    .=    "Host:    $ghost
";
                $sessionQuery    .=    "Accept:    */*
";
                $sessionQuery    .=    "User-Agent:    Mozilla/4.0    (compatible;    MSIE    5.00;    Windows    98)
";
                $sessionQuery    .=    "Connection:    Close

";
                $errno    =    "";
                $errstr    =    "";
                $m_fp    =    fsockopen($ghost,    80,    $errno,    $errstr,10)    or    die($ghost.'<br    />');
                fwrite($m_fp,$sessionQuery);
                $lnum    =    0;
                //获取详细应答头
                $gcookie    =    "";
                while(!feof($m_fp))
                {
                                $line    =    trim(fgets($m_fp,256));
                                if($line    ==    ""    ||    $lnum>100)
                                {
                                                break;
                                }
                                else
                                {
                                                if(preg_match("/^cookie/i",    $line))
                                                {
                                                                $gcookie    =    $line;
                                                                break;
                                                }
                                }
                }
                fclose($m_fp);
                return    $gcookie;
}
/**
    *        获得网址的host和query部份
    *
    *    @access                public
    *    @param                    string        $gurl        调整地址
    *    @return                string
    */
function    GetHostInfo($gurl)
{
                $gurl    =    preg_replace("/^http:///i",    "",    trim($gurl));
                $garr['host']    =    preg_replace("//(.*)$/i",    "",    $gurl);
                $garr['query']    =    "/".preg_replace("/^([^/]*)//i",    "",    $gurl);
                return    $garr;
}
?>