我知道有大量的$_SERVER变量头可用于IP地址检索。我想知道是否有一个普遍的共识，如何最准确地检索用户的真实IP地址(好知道没有方法是完美的)使用上述变量?
我花了一些时间试图找到一个深入的解决方案，并根据一些来源提出了以下代码。如果有人能在答案中找出漏洞，或者提供一些更准确的信息，我会很高兴。
edit包含来自@Alix的优化
/**
* Retrieves the best guess of the client's actual IP address.
* Takes into account numerous HTTP proxy headers due to variations
* in how different ISPs handle IP addresses in headers between hops.
*/
public function get_ip_address() {
// Check for shared internet/ISP IP
if (!empty($_SERVER['HTTP_CLIENT_IP']) && $this->validate_ip($_SERVER['HTTP_CLIENT_IP']))
return $_SERVER['HTTP_CLIENT_IP'];
// Check for IPs passing through proxies
if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
// Check if multiple IP addresses exist in var
$iplist = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
foreach ($iplist as $ip) {
if ($this->validate_ip($ip))
return $ip;
}
}
}
if (!empty($_SERVER['HTTP_X_FORWARDED']) && $this->validate_ip($_SERVER['HTTP_X_FORWARDED']))
return $_SERVER['HTTP_X_FORWARDED'];
if (!empty($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']) && $this->validate_ip($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']))
return $_SERVER['HTTP_X_CLUSTER_CLIENT_IP'];
if (!empty($_SERVER['HTTP_FORWARDED_FOR']) && $this->validate_ip($_SERVER['HTTP_FORWARDED_FOR']))
return $_SERVER['HTTP_FORWARDED_FOR'];
if (!empty($_SERVER['HTTP_FORWARDED']) && $this->validate_ip($_SERVER['HTTP_FORWARDED']))
return $_SERVER['HTTP_FORWARDED'];
// Return unreliable IP address since all else failed
return $_SERVER['REMOTE_ADDR'];
}
/**
* Ensures an IP address is both a valid IP address and does not fall within
* a private network range.
*
* @access public
* @param string $ip
*/
public function validate_ip($ip) {
if (filter_var($ip, FILTER_VALIDATE_IP,
FILTER_FLAG_IPV4 |
FILTER_FLAG_IPV6 |
FILTER_FLAG_NO_PRIV_RANGE |
FILTER_FLAG_NO_RES_RANGE) === false)
return false;
self::$ip = $ip;
return true;
}
警告之词(更新)
REMOTE_ADDR仍然表示最可靠的IP地址来源。这里提到的其他$_SERVER变量很容易被远程客户端欺骗。此解决方案的目的是试图确定位于代理后面的客户机的IP地址。出于一般目的，您可以考虑将其与直接从$_SERVER['REMOTE_ADDR']返回的IP地址结合使用，并存储两者。
对于99.9%的用户，这个解决方案将完美地满足您的需求。它不能保护您免受0.1%的恶意用户通过注入他们自己的请求头来滥用您的系统。如果某些关键任务依赖于IP地址，请使用REMOTE_ADDR，而不必费心满足代理背后的需求。
/**
* Sanitizes IPv4 address according to Ilia Alshanetsky's book
* "php|architect?s Guide to PHP Security", chapter 2, page 67.
*
* @param string $ip An IPv4 address
*/
public static function sanitizeIpAddress($ip = '')
{
if ($ip == '')
{
$rtnStr = '0.0.0.0';
}
else
{
$rtnStr = long2ip(ip2long($ip));
}
return $rtnStr;
}
//---------------------------------------------------
/**
* Returns the sanitized HTTP_X_FORWARDED_FOR server variable.
*
*/
public static function getXForwardedFor()
{
if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
{
$rtnStr = $_SERVER['HTTP_X_FORWARDED_FOR'];
}
elseif (isset($HTTP_SERVER_VARS['HTTP_X_FORWARDED_FOR']))
{
$rtnStr = $HTTP_SERVER_VARS['HTTP_X_FORWARDED_FOR'];
}
elseif (getenv('HTTP_X_FORWARDED_FOR'))
{
$rtnStr = getenv('HTTP_X_FORWARDED_FOR');
}
else
{
$rtnStr = '';
}
// Sanitize IPv4 address (Ilia Alshanetsky):
if ($rtnStr != '')
{
$rtnStr = explode(', ', $rtnStr);
$rtnStr = self::sanitizeIpAddress($rtnStr[0]);
}
return $rtnStr;
}
//---------------------------------------------------
/**
* Returns the sanitized REMOTE_ADDR server variable.
*
*/
public static function getRemoteAddr()
{
if (isset($_SERVER['REMOTE_ADDR']))
{
$rtnStr = $_SERVER['REMOTE_ADDR'];
}
elseif (isset($HTTP_SERVER_VARS['REMOTE_ADDR']))
{
$rtnStr = $HTTP_SERVER_VARS['REMOTE_ADDR'];
}
elseif (getenv('REMOTE_ADDR'))
{
$rtnStr = getenv('REMOTE_ADDR');
}
else
{
$rtnStr = '';
}
// Sanitize IPv4 address (Ilia Alshanetsky):
if ($rtnStr != '')
{
$rtnStr = explode(', ', $rtnStr);
$rtnStr = self::sanitizeIpAddress($rtnStr[0]);
}
return $rtnStr;
}
//---------------------------------------------------
/**
* Returns the sanitized remote user and proxy IP addresses.
*
*/
public static function getIpAndProxy()
{
$xForwarded = self::getXForwardedFor();
$remoteAddr = self::getRemoteAddr();
if ($xForwarded != '')
{
$ip = $xForwarded;
$proxy = $remoteAddr;
}
else
{
$ip = $remoteAddr;
$proxy = '';
}
return array($ip, $proxy);
}
我的回答基本上是@AlixAxel的回答的一个经过润色、完全验证和完全打包的版本:
<?php
/* Get the 'best known' client IP. */
if (!function_exists('getClientIP'))
{
function getClientIP()
{
if (isset($_SERVER["HTTP_CF_CONNECTING_IP"]))
{
$_SERVER['REMOTE_ADDR'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
};
foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key)
{
if (array_key_exists($key, $_SERVER))
{
foreach (explode(',', $_SERVER[$key]) as $ip)
{
$ip = trim($ip);
if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false)
{
return $ip;
};
};
};
};
return false;
};
};
$best_known_ip = getClientIP();
if(!empty($best_known_ip))
{
$ip = $clients_ip = $client_ip = $client_IP = $best_known_ip;
}
else
{
$ip = $clients_ip = $client_ip = $client_IP = $best_known_ip = '';
};
?>
变化:
它简化了函数名(使用'camelCase'格式样式)。
它包括一个检查，以确保函数没有在代码的另一部分中声明。
它还考虑了“CloudFlare”的兼容性。
它将多个“ip相关”变量名称初始化为'getClientIP'函数的返回值。
它确保如果函数没有返回有效的IP地址，所有变量都被设置为空字符串，而不是null。
它只有(45)行代码。
只是个VB。NET版的答案:
Private Function GetRequestIpAddress() As IPAddress
Dim serverVariables = HttpContext.Current.Request.ServerVariables
Dim headersKeysToCheck = {"HTTP_CLIENT_IP", _
"HTTP_X_FORWARDED_FOR", _
"HTTP_X_FORWARDED", _
"HTTP_X_CLUSTER_CLIENT_IP", _
"HTTP_FORWARDED_FOR", _
"HTTP_FORWARDED", _
"REMOTE_ADDR"}
For Each thisHeaderKey In headersKeysToCheck
Dim thisValue = serverVariables.Item(thisHeaderKey)
If thisValue IsNot Nothing Then
Dim validAddress As IPAddress = Nothing
If IPAddress.TryParse(thisValue, validAddress) Then
Return validAddress
End If
End If
Next
Return Nothing
End Function
来自Symfony的Request类
https://github.com/symfony/symfony/blob/1bd125ec4a01220878b3dbc3ec3156b073996af9/src/Symfony/Component/HttpFoundation/Request.php
const HEADER_FORWARDED = 'forwarded';
const HEADER_CLIENT_IP = 'client_ip';
const HEADER_CLIENT_HOST = 'client_host';
const HEADER_CLIENT_PROTO = 'client_proto';
const HEADER_CLIENT_PORT = 'client_port';
/**
* Names for headers that can be trusted when
* using trusted proxies.
*
* The FORWARDED header is the standard as of rfc7239.
*
* The other headers are non-standard, but widely used
* by popular reverse proxies (like Apache mod_proxy or Amazon EC2).
*/
protected static $trustedHeaders = array(
self::HEADER_FORWARDED => 'FORWARDED',
self::HEADER_CLIENT_IP => 'X_FORWARDED_FOR',
self::HEADER_CLIENT_HOST => 'X_FORWARDED_HOST',
self::HEADER_CLIENT_PROTO => 'X_FORWARDED_PROTO',
self::HEADER_CLIENT_PORT => 'X_FORWARDED_PORT',
);
/**
* Returns the client IP addresses.
*
* In the returned array the most trusted IP address is first, and the
* least trusted one last. The "real" client IP address is the last one,
* but this is also the least trusted one. Trusted proxies are stripped.
*
* Use this method carefully; you should use getClientIp() instead.
*
* @return array The client IP addresses
*
* @see getClientIp()
*/
public function getClientIps()
{
$clientIps = array();
$ip = $this->server->get('REMOTE_ADDR');
if (!$this->isFromTrustedProxy()) {
return array($ip);
}
if (self::$trustedHeaders[self::HEADER_FORWARDED] && $this->headers->has(self::$trustedHeaders[self::HEADER_FORWARDED])) {
$forwardedHeader = $this->headers->get(self::$trustedHeaders[self::HEADER_FORWARDED]);
preg_match_all('{(for)=("?\[?)([a-z0-9\.:_\-/]*)}', $forwardedHeader, $matches);
$clientIps = $matches[3];
} elseif (self::$trustedHeaders[self::HEADER_CLIENT_IP] && $this->headers->has(self::$trustedHeaders[self::HEADER_CLIENT_IP])) {
$clientIps = array_map('trim', explode(',', $this->headers->get(self::$trustedHeaders[self::HEADER_CLIENT_IP])));
}
$clientIps[] = $ip; // Complete the IP chain with the IP the request actually came from
$firstTrustedIp = null;
foreach ($clientIps as $key => $clientIp) {
// Remove port (unfortunately, it does happen)
if (preg_match('{((?:\d+\.){3}\d+)\:\d+}', $clientIp, $match)) {
$clientIps[$key] = $clientIp = $match[1];
}
if (!filter_var($clientIp, FILTER_VALIDATE_IP)) {
unset($clientIps[$key]);
}
if (IpUtils::checkIp($clientIp, self::$trustedProxies)) {
unset($clientIps[$key]);
// Fallback to this when the client IP falls into the range of trusted proxies
if (null === $firstTrustedIp) {
$firstTrustedIp = $clientIp;
}
}
}
// Now the IP chain contains only untrusted proxies and the client IP
return $clientIps ? array_reverse($clientIps) : array($firstTrustedIp);
}
