使用PHP Curl的FTPS获得部分下载(FTPS with PHP Curl getting partial download)

 我有一个问题，使用php curl在ftps上使用隐式ssl检索文件（如下所述： ftp_ssl_connect，隐式ftp超过tls ）。 问题是有时候 - 大概有5％的时间，我最终会部分下载。 
 
 我的班级或多或少地改编自改编自Nico Westerdale的答案，以下是相关方法： 
 
class ftps {

    private $server;
    private $username;
    private $password;
    private $curlhandle;
    public $dir = '/';

    public function __construct($server, $username, $password) {
        $this->server = $server;
        $this->username = $username;
        $this->password = $password;
        $this->curlhandle = curl_init();
    }

    private function common($remote) {
        curl_reset($this->curlhandle);
        curl_setopt($this->curlhandle, CURLOPT_URL, 'ftps://' . $this->server . '/' . $remote);
        curl_setopt($this->curlhandle, CURLOPT_USERPWD, $this->username . ':' . $this->password);
        curl_setopt($this->curlhandle, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($this->curlhandle, CURLOPT_SSL_VERIFYHOST, FALSE);
        curl_setopt($this->curlhandle, CURLOPT_FTP_SSL, CURLFTPSSL_TRY);
        curl_setopt($this->curlhandle, CURLOPT_FTPSSLAUTH, CURLFTPAUTH_TLS);
        return $this->curlhandle;
    }

    public function download($filepath, $local = false) {
        $filename = basename($filepath);
        $remote   = dirname($filepath);
        if ($remote == '.') {
            $remote = $this->dir;
        }
        if ($local === false) {
            $local = $filename;
        }

        if ($fp = fopen($local, 'w')) {
            $this->curlhandle = self::common($remote . $filename);
            curl_setopt($this->curlhandle, CURLOPT_UPLOAD, 0);
            curl_setopt($this->curlhandle, CURLOPT_FILE, $fp);
            curl_exec($this->curlhandle);
            if (curl_error($this->curlhandle)) {
                return false;
            } else {
                return $local;
            }
        }
        return false;
    }
}
 
 我使用它是这样的： 
 
$ftps = new ftps('example.com','john_doe','123456');
$ftps->download('remote_filename','local_filename');
 
 正如我上面提到的， 除了大约5％的时间结果是部分下载的文件以外 ，这个工作几乎完美无缺。 然后我检查远程服务器，并且能够验证文件确实存在于其中 - 再次尝试脚本并且它总是在第二次尝试时获取整个文件。 
 
 什么会导致使用像这样的卷曲的间歇性问题？ 我的下一步行动是实施某种校验和，并继续下载尝试，直到所有的哈希结果，但这种感觉更像是一种琐碎的解决方法，而不是真正的解决方案，并且很高兴知道问题的实际根源。 

I'm having an issue retrieving a file using php curl over ftps with implicit ssl (as discussed here: ftp_ssl_connect with implicit ftp over tls). The problem is that sometimes - probably 5% of the time, I end up with a partial download.
 
My class is more or less adapted from adapted from Nico Westerdale's answer and here are the relevant methods:
 
class ftps {

    private $server;
    private $username;
    private $password;
    private $curlhandle;
    public $dir = '/';

    public function __construct($server, $username, $password) {
        $this->server = $server;
        $this->username = $username;
        $this->password = $password;
        $this->curlhandle = curl_init();
    }

    private function common($remote) {
        curl_reset($this->curlhandle);
        curl_setopt($this->curlhandle, CURLOPT_URL, 'ftps://' . $this->server . '/' . $remote);
        curl_setopt($this->curlhandle, CURLOPT_USERPWD, $this->username . ':' . $this->password);
        curl_setopt($this->curlhandle, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($this->curlhandle, CURLOPT_SSL_VERIFYHOST, FALSE);
        curl_setopt($this->curlhandle, CURLOPT_FTP_SSL, CURLFTPSSL_TRY);
        curl_setopt($this->curlhandle, CURLOPT_FTPSSLAUTH, CURLFTPAUTH_TLS);
        return $this->curlhandle;
    }

    public function download($filepath, $local = false) {
        $filename = basename($filepath);
        $remote   = dirname($filepath);
        if ($remote == '.') {
            $remote = $this->dir;
        }
        if ($local === false) {
            $local = $filename;
        }

        if ($fp = fopen($local, 'w')) {
            $this->curlhandle = self::common($remote . $filename);
            curl_setopt($this->curlhandle, CURLOPT_UPLOAD, 0);
            curl_setopt($this->curlhandle, CURLOPT_FILE, $fp);
            curl_exec($this->curlhandle);
            if (curl_error($this->curlhandle)) {
                return false;
            } else {
                return $local;
            }
        }
        return false;
    }
}
 
I'm using it like this:
 
$ftps = new ftps('example.com','john_doe','123456');
$ftps->download('remote_filename','local_filename');
 
As I mentioned above, this works almost flawlessly except about 5% of the time the result is a partially downloaded file. I then check the remote server and am able to verify that the file is indeed there in it's entirety - try the script again and it invariably gets the whole file on a second attempt.
 
What would cause an intermittent issue using curl like this? My next move would be to implement some kind of checksum and continue download attempts until everything hashes but this feels more like a sloppy workaround than a true solution and it would be nice to know the actual root of the problem.

原文：https://stackoverflow.com/questions/47001712