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<?php
namespace React\Dns\Config;
use RuntimeException;
class Config
{
/**
* Loads the system DNS configuration
*
* Note that this method may block while loading its internal files and/or
* commands and should thus be used with care! While this should be
* relatively fast for most systems, it remains unknown if this may block
* under certain circumstances. In particular, this method should only be
* executed before the loop starts, not while it is running.
*
* Note that this method will try to access its files and/or commands and
* try to parse its output. Currently, this will only parse valid nameserver
* entries from its output and will ignore all other output without
* complaining.
*
* Note that the previous section implies that this may return an empty
* `Config` object if no valid nameserver entries can be found.
*
* @return self
* @codeCoverageIgnore
*/
public static function loadSystemConfigBlocking()
{
// Use WMIC output on Windows
if (DIRECTORY_SEPARATOR === '\\') {
return self::loadWmicBlocking();
}
// otherwise (try to) load from resolv.conf
try {
return self::loadResolvConfBlocking();
} catch (RuntimeException $ignored) {
// return empty config if parsing fails (file not found)
return new self();
}
}
/**
* Loads a resolv.conf file (from the given path or default location)
*
* Note that this method blocks while loading the given path and should
* thus be used with care! While this should be relatively fast for normal
* resolv.conf files, this may be an issue if this file is located on a slow
* device or contains an excessive number of entries. In particular, this
* method should only be executed before the loop starts, not while it is
* running.
*
* Note that this method will throw if the given file can not be loaded,
* such as if it is not readable or does not exist. In particular, this file
* is not available on Windows.
*
* Currently, this will only parse valid "nameserver X" lines from the
* given file contents. Lines can be commented out with "#" and ";" and
* invalid lines will be ignored without complaining. See also
* `man resolv.conf` for more details.
*
* Note that the previous section implies that this may return an empty
* `Config` object if no valid "nameserver X" lines can be found. See also
* `man resolv.conf` which suggests that the DNS server on the localhost
* should be used in this case. This is left up to higher level consumers
* of this API.
*
* @param ?string $path (optional) path to resolv.conf file or null=load default location
* @return self
* @throws RuntimeException if the path can not be loaded (does not exist)
*/
public static function loadResolvConfBlocking($path = null)
{
if ($path === null) {
$path = '/etc/resolv.conf';
}
$contents = @file_get_contents($path);
if ($contents === false) {
throw new RuntimeException('Unable to load resolv.conf file "' . $path . '"');
}
preg_match_all('/^nameserver\s+(\S+)\s*$/m', $contents, $matches);
$config = new self();
$config->nameservers = $matches[1];
return $config;
}
/**
* Loads the DNS configurations from Windows's WMIC (from the given command or default command)
*
* Note that this method blocks while loading the given command and should
* thus be used with care! While this should be relatively fast for normal
* WMIC commands, it remains unknown if this may block under certain
* circumstances. In particular, this method should only be executed before
* the loop starts, not while it is running.
*
* Note that this method will only try to execute the given command try to
* parse its output, irrespective of whether this command exists. In
* particular, this command is only available on Windows. Currently, this
* will only parse valid nameserver entries from the command output and will
* ignore all other output without complaining.
*
* Note that the previous section implies that this may return an empty
* `Config` object if no valid nameserver entries can be found.
*
* @param ?string $command (advanced) should not be given (NULL) unless you know what you're doing
* @return self
* @link https://ss64.com/nt/wmic.html
*/
public static function loadWmicBlocking($command = null)
{
$contents = shell_exec($command === null ? 'wmic NICCONFIG get "DNSServerSearchOrder" /format:CSV' : $command);
preg_match_all('/(?<=[{;,"])([\da-f.:]{4,})(?=[};,"])/i', $contents, $matches);
$config = new self();
$config->nameservers = $matches[1];
return $config;
}
public $nameservers = array();
}
|
