从FTP传输文件并让用户同时下载它 [英] Streaming a file fromFTP and letting user to download it at the same time

问题描述

我正在创建一个备份系统，备份将自动生成，因此我将把备份存储在不同的服务器上，但是当我想要下载它们时，我希望链接是一次性链接，但这不是不难做出，但为了保证安全，我正在考虑存储这些文件，以免他们通过另一台服务器上的http进行访问。

因此，我要做的是通过ftp连接，将文件下载到主服务器，然后将其下载并删除，但是这会花费很长时间备份很大，有没有一种方法可以通过FTP进行流式传输，而不需要显示下载人员的实际位置，也不需要将其存储在服务器上？

解决方案

这是一个使用卷曲。它指定了一个读取回调函数，当可以从FTP读取数据时，将调用该回调函数，并将数据输出到浏览器，以在FTP备份服务器与FTP服务器进行同步下载的同时下载到客户端。

这是一个非常基本的例子，您可以扩展它。

 < php 
 
 // ftp URL到文件
 $ url ='ftp://ftp.mozilla.org/pub/firefox/nightly/latest-firefox-3.6.x/firefox-3.6 .29pre.en-US.linux-i686.tar.bz2' ; 
 
 //使用FTP地址初始化curl会话
 $ ch = curl_init（$ url）; 
 
 //指定读取数据的回调函数
 curl_setopt（$ ch，CURLOPT_READFUNCTION，'readCallback'）; 
 
 //发送客户端下载头
头（'Content-type：application / octet-stream'）; 
 header（'Content-Disposition：attachment; filename =backup.tar.bz2'）; 
 
 //执行请求，当数据可用时，我们的读取回调将被调用
 curl_exec（$ ch）; 
 
 
 //读取回调函数，需要3个参数，curl句柄，要读取的流以及读取的最大字节数
函数readCallback（$ curl，$流，$ maxRead）
 {
 //从ftp流读取数据
 $ read = fgets（$ stream，$ maxRead）; 
 
 //回显刚刚读给客户端的内容，这些内容有助于他们的总下载
 echo $ read; 
 
 //返回读取的数据，使函数继续运行
 return $ read; 
} 
  

请参阅 curl_setopt（）获取更多关于 CURLOPT_READFUNCTION 选项的信息。

I'm creating a backup system, where backups will be generated automaticly, so I will be storing backups on a different server, however when I want to download them, I want the link to be a one time link, this isn't hard to make, however to make this secure I was thinking about storing the files so their not accesible via http on the other server.

So what I would do is connet via ftp, download the file to the main server, then present it for download and deleteit, however this will take a long time if the backup is large, is there a way to stream it from FTP without showing the person who is downloadiong the actual location and not store it on the server?

解决方案

Here is a very basic example using cURL. It specifies a read callback which will be called when data is available to be read from FTP, and outputs the data to the browser to serve a simultaneous download to the client while the FTP transaction is taking place with the backup server.

This is a very basic exmaple which you can expand on.

<?php

// ftp URL to file
$url = 'ftp://ftp.mozilla.org/pub/firefox/nightly/latest-firefox-3.6.x/firefox-3.6.29pre.en-US.linux-i686.tar.bz2';

// init curl session with FTP address
$ch = curl_init($url);

// specify a callback function for reading data
curl_setopt($ch, CURLOPT_READFUNCTION, 'readCallback');

// send download headers for client
header('Content-type: application/octet-stream');
header('Content-Disposition: attachment; filename="backup.tar.bz2"');

// execute request, our read callback will be called when data is available
curl_exec($ch);


// read callback function, takes 3 params, the curl handle, the stream to read from and the maximum number of bytes to read    
function readCallback($curl, $stream, $maxRead)
{
    // read the data from the ftp stream
    $read = fgets($stream, $maxRead);

    // echo the contents just read to the client which contributes to their total download
    echo $read;

    // return the read data so the function continues to operate
    return $read;
}

See curl_setopt() for more info on the CURLOPT_READFUNCTION option.

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