I want to create sub-domains using PHP on the fly. Suppose a user registers himself as a name "ABC". Then I want to create a sub-domain named 'ABC.mydomain.com' automatically by PHP. I'm using a linux based server.
Would anyone point me to the right direction?
You should be aware that this is easily done using wildcard DNS records. This way:
you do not have to register each user to your DNS server.
your DNS A-record may contain as few as 1 record: e.g *.mydomain.com -> 12.34.56.78
your web server at 12.34.56.78 have to be configured to accept wildcard
In your server-side scripts, you dynamically resolve "abc.mydomain.com" on your controller/routing code by checking if abc is an existing active username, sample code below:
<?php
// Note that I am using SERVER_NAME vs HTTP_HOST,
// but for additional safety also check your httpd.conf
list($user, $domain) = split("\.", $_SERVER['SERVER_NAME'], 2);
// check if domain is correct,
// or you can leave this part if the web server checks this already
if ($domain === "mydomain.com") {
// here, you verify $user if existent/active
// and reroute or render the page depending on request params
// ...
}
?>
Related
I am working on an php website,
my website url is something like
http://www.xyz.com/hosted/abc.com
I want to access the pages with above url with a cname like http://abc.xyz.com
Means if i type http://abc.xyz.com as url it should internally serve me the pages for http://www.xyz.com/hosted/abc.com.
Please suggest,if anyone know how to achieve this ?Thanks in advance.
If you use bind for dns server you must make a DNS zone manually and add an A record *.xyz.com. into this zone to redirect all the hosts like *.xyz.com to your web server.
Or if you use cPanel go to Simple DNS Zone Editor add an A Record with this name : *.xyz.com. and set Address your server's IP address.
If you use another Control Panel or DNS Server Service you have to read manual to handle requests for *.xyz.com
Then in your php code you can get the requested cname :
$host = $_SERVER['HTTP_HOST'];
$match = preg_match("([a-zA-Z0-9\-])\.xyz\.com");
$cname = $match[0];
I'm building an application that uses sub domains and custom domain names that sit in the database for users, so if a request comes from another domain I'll check from the database if that custom url is indeed there or when the request comes from a subdomain, I'll check if that's there. If it is I do my stuff.
Consider this a simple example of I'm looking for:
if(is_user_request())
{
$url = get_url();
// assuming that get_url() magically decides whether to output ..
// a custom domain (http://domain.tld)
// or a subdomain's first part (eg. "this".domain.tld)
}
else
{
// otherwise it's not a sub domain nor a custom domain,
// so we're dealing with our own main site.
}
Now before you go ahead assuming that because I have 0 rep, I'm here asking for "teh codes". I have a completely working way of doing this, which is the following:
// hosts
$hosts = explode('.', $_SERVER['HTTP_HOST']);
// if there is a subdomain and that's under our $sitename
if(!empty($hosts[1]) AND $hosts[1] === Config::get('domain_mid_name'))
{
$url = $hosts[0];
$url_custom = false;
}
// if there is no subdomain, but the domain is our $sitename
elseif(!empty($hosts[0]) AND $hosts[0] === Config::get('domain_mid_name') AND !empty($hosts[1]) AND $hosts[1] !== Config::get('domain_mid_name'))
{
$url = false;
$url_custom = false;
}
// otherwise it's most likely that the request
// came from a entirely different domain name.
// which means it's probably $custom_site
else
{
$url = false;
$url_custom = implode('.', $hosts);
}
if($url)
{
return $url;
}
if($url_custom)
{
return $url_custom;
}
However, I'm sure there are better way of doing this. Because first of all, HTTP_HOST does not include 'http://', so I need to add that manually and I'm pretty sure this entire if, else thing is just an overkill. So, people smarter than me, enlighten me, please.
Oh and, no .. I do not have pre-defined sub-domains. I have a simple wildcard *.domain.tld set up, so all sub-domains go to the main script. I'm just saying this because from my search for a solution I found numerous answers that suggested to manually create a sub-domain, which is not even remotely related to what I'm asking, so let's skip that subject.
$_SERVER['HTTP_HOST'] is the correct way to do it unless you want to pass different parameters from your web server into PHP.
As for the protocol, be aware the request protocol should be determined by $_SERVER['HTTPS'] rather than assuming it's http.
For extracting the subdomain you could look at using array_shift and then running
$subdomain = array_shift(explode('.', $_SERVER['HTTP_HOST']));
But generally what you have is how it should be done.
As already said, $_SERVER['HTTP_HOST'] is the way to go.
But there are errors in your code. You're assuming that host names sent consist of 2 or 3 components but you can't be sure of that. You should at least check count($hosts) too.
If by example you use domain.tld for your own site then you're better off with first checking if domain.tld is sent (you return your page, fast); then see if substr($_SERVER['HTTP_HOST']...,-11)==='.domain.tld' and if so, return the subsite (works with any level of subdomain, still fast); else error-recovery, since a completely foreign domain has been routed to you. The key thing to note is that domain matching from the hierarchy's top means matching the hostname strings right-aligned:
.domain.tld | subsite-pattern
sub12.domain.tld | MATCH
sub12.dumain.tld | NO MATCH
sub12domain.tld | NO MATCH
I have my site on the server http://www.myserver.uk.com.
On this server I have two domains:
one.com and two.com
I would like to get the current domain using PHP, but if I use $_SERVER['HTTP_HOST'] then it is showing me
myserver.uk.com
instead of:
one.com or two.com
How can I get the domain, and not the server name?
Try using this:
$_SERVER['SERVER_NAME']
Or parse:
$_SERVER['REQUEST_URI']
Reference: apache_request_headers()
The best use would be
echo $_SERVER['HTTP_HOST'];
And it can be used like this:
if (strpos($_SERVER['HTTP_HOST'], 'banana.com') !== false) {
echo "Yes this is indeed the banana.com domain";
}
This code below is a good way to see all the variables in $_SERVER in a structured HTML output with your keywords highlighted that halts directly after execution. Since I do sometimes forget which one to use myself - I think this can be nifty.
<?php
// Change banana.com to the domain you were looking for..
$wordToHighlight = "banana.com";
$serverVarHighlighted = str_replace( $wordToHighlight, '<span style=\'background-color:#883399; color: #FFFFFF;\'>'. $wordToHighlight .'</span>', $_SERVER );
echo "<pre>";
print_r($serverVarHighlighted);
echo "</pre>";
exit();
?>
The only secure way of doing this
The only guaranteed secure method of retrieving the current domain is to store it in a secure location yourself.
Most frameworks take care of storing the domain for you, so you will want to consult the documentation for your particular framework. If you're not using a framework, consider storing the domain in one of the following places:
Secure methods of storing the domain
Used By
A configuration file
Joomla, Drupal/Symfony
The database
WordPress
An environmental variable
Laravel
A service registry
Kubernetes DNS
The following work... but they're not secure
Hackers can make the following variables output whatever domain they want. This can lead to cache poisoning and barely noticeable phishing attacks.
$_SERVER['HTTP_HOST']
This gets the domain from the request headers which are open to manipulation by hackers. Same with:
$_SERVER['SERVER_NAME']
This one can be made better if the Apache setting usecanonicalname is turned off; in which case $_SERVER['SERVER_NAME'] will no longer be allowed to be populated with arbitrary values and will be secure. This is, however, non-default and not as common of a setup.
In popular systems
Below is how you can get the current domain in the following frameworks/systems:
WordPress
$urlparts = parse_url(home_url());
$domain = $urlparts['host'];
If you're constructing a URL in WordPress, just use home_url or site_url, or any of the other URL functions.
Laravel
request()->getHost()
The request()->getHost function is inherited from Symfony, and has been secure since the 2013 CVE-2013-4752 was patched.
Drupal
The installer does not yet take care of making this secure (issue #2404259). But in Drupal 8 there is documentation you can you can follow at Trusted Host Settings to secure your Drupal installation after which the following can be used:
\Drupal::request()->getHost();
Other frameworks
Feel free to edit this answer to include how to get the current domain in your favorite framework. When doing so, please include a link to the relevant source code or to anything else that would help me verify that the framework is doing things securely.
Addendum
Exploitation examples:
Cache poisoning can happen if a botnet continuously requests a page using the wrong hosts header. The resulting HTML will then include links to the attackers website where they can phish your users. At first the malicious links will only be sent back to the hacker, but if the hacker does enough requests, the malicious version of the page will end up in your cache where it will be distributed to other users.
A phishing attack can happen if you store links in the database based on the hosts header. For example, let say you store the absolute URL to a user's profiles on a forum. By using the wrong header, a hacker could get anyone who clicks on their profile link to be sent a phishing site.
Password reset poisoning can happen if a hacker uses a malicious hosts header when filling out the password reset form for a different user. That user will then get an email containing a password reset link that leads to a phishing site. Another more complex form of this skips the user having to do anything by getting the email to bounce and resend to one of the hacker's SMTP servers (for example CVE-2017-8295.)
Here are some more malicious examples
Additional Caveats and Notes:
When usecanonicalname is turned off the $_SERVER['SERVER_NAME'] is populated with the same header $_SERVER['HTTP_HOST'] would have used anyway (plus the port). This is Apache's default setup. If you or DevOps turns this on then you're okay -- ish -- but do you really want to rely on a separate team, or yourself three years in the future, to keep what would appear to be a minor configuration at a non-default value? Even though this makes things secure, I would caution against relying on this setup.
Red Hat, however, does turn usecanonical on by default [source].
If serverAlias is used in the virtual hosts entry, and the aliased domain is requested, $_SERVER['SERVER_NAME'] will not return the current domain, but will return the value of the serverName directive.
If the serverName cannot be resolved, the operating system's hostname command is used in its place [source].
If the host header is left out, the server will behave as if usecanonical
was on [source].
Lastly, I just tried exploiting this on my local server, and was unable to spoof the hosts header. I'm not sure if there was an update to Apache that addressed this, or if I was just doing something wrong. Regardless, this header would still be exploitable in environments where virtual hosts are not being used.
A Little Rant:
This question received hundreds of thousands of views without a single mention of the security problems at hand! It shouldn't be this way, but just because a Stack Overflow answer is popular, that doesn't mean it is secure.
Using $_SERVER['HTTP_HOST'] gets me (subdomain.)maindomain.extension. It seems like the easiest solution to me.
If you're actually 'redirecting' through an iFrame, you could add a GET parameter which states the domain.
<iframe src="myserver.uk.com?domain=one.com"/>
And then you could set a session variable that persists this data throughout your application.
Try $_SERVER['SERVER_NAME'].
Tips: Create a PHP file that calls the function phpinfo() and see the "PHP Variables" section. There are a bunch of useful variables we never think of there.
To get the domain:
$_SERVER['HTTP_HOST']
Domain with protocol:
$protocol = strpos(strtolower($_SERVER['SERVER_PROTOCOL']), 'https') === FALSE ? 'http' : 'https';
$domainLink = $protocol . '://' . $_SERVER['HTTP_HOST'];
Protocol, domain, and queryString total:
$url = $protocol . '://' . $_SERVER['HTTP_HOST'] . '?' . $_SERVER['QUERY_STRING'];
**As the $_SERVER['SERVER_NAME'] is not reliable for multi-domain hosting!
I know this might not be entirely on the subject, but in my experience, I find storing the WWW-ness of the current URL in a variable useful.
In addition, please see my comment below, to see what this is getting at.
This is important when determining whether to dispatch Ajax calls with "www", or without:
$.ajax("url" : "www.site.com/script.php", ...
$.ajax("url" : "site.com/script.php", ...
When dispatching an Ajax call the domain name must match that of in the browser's address bar, and otherwise you will have an Uncaught SecurityError in the console.
So I came up with this solution to address the issue:
<?php
substr($_SERVER['SERVER_NAME'], 0, 3) == "www" ? $WWW = true : $WWW = false;
if ($WWW) {
/* We have www.example.com */
} else {
/* We have example.com */
}
?>
Then, based on whether $WWW is true, or false run the proper Ajax call.
I know this might sound trivial, but this is such a common problem that is easy to trip over.
Everybody is using the parse_url function, but sometimes a user may pass the argument in different formats.
So as to fix that, I have created a function. Check this out:
function fixDomainName($url='')
{
$strToLower = strtolower(trim($url));
$httpPregReplace = preg_replace('/^http:\/\//i', '', $strToLower);
$httpsPregReplace = preg_replace('/^https:\/\//i', '', $httpPregReplace);
$wwwPregReplace = preg_replace('/^www\./i', '', $httpsPregReplace);
$explodeToArray = explode('/', $wwwPregReplace);
$finalDomainName = trim($explodeToArray[0]);
return $finalDomainName;
}
Just pass the URL and get the domain.
For example,
echo fixDomainName('https://stackoverflow.com');
will return:
stackoverflow.com
And in some situation:
echo fixDomainName('stackoverflow.com/questions/id/slug');
And it will also return stackoverflow.com.
This quick & dirty works for me.
Whichever way you get the string containing the domain you want to extract, i.e. using a super global -$_SERVER['SERVER_NAME']- or, say, in Drupal: global $base_url, regex is your friend:
global $base_url;
preg_match("/\w+\.\w+$/", $base_url, $matches);
$domain = $matches[0];
The particular regex string I am using in the example will only capture the last two components of the $base_url string, of course, but you can add as many "\w+." as desired.
Hope it helps.
I am on shared hosting and on a add on domain.
I need to create subdomain for each user of my website like if the username is jeff then he should have a url jeff.mydomain.com.
How can I create it programmatically using PHP?
There's two parts to this. Firstly you'll need to setup a wildcard dns entry.
Once you've got that setup you should have all your requests pointed back to a single domain. From there you can then use php to figure out which domain you're currently on:
$domain = $_SERVER['HTTP_HOST'];
$base = 'mydomain.com';
$user = substr($domain, 0, -(strlen($base)+1));// the user part of the domain
if(!empty($user)) {
$user = sanatiseUser($user);
require_once $user.'.php';
}
You need to set apache to listen for all domains coming into a specific IP.
You then need to setup a wildcard DNS entry to point *.domain.com to that IP.
Then inside your app, use $_SERVER['HTTP_HOST'] to determine which user to load.
How can I get real host name by not using $_SERVER['SERVER_NAME'] in PHP? Is there other more reliable way to get it ?
I have created a function which gets host name from the path to the domain.
I would like to avoid using $_SERVER['SERVER_NAME'] variable, because it can be faked by sending modified headers in the HTTP request.
This is my current implementation (this works if the path has an actual domain name in it. For instance: /vhosts/website.com/public_html):
function getServerName() {
$path = realpath(__FILE__);
$url = array();
preg_match_all("/\/[a-z0-9-]+(\.[a-z0-9-]+)+/i", $path, $url);
// 4 is minimum requirement for the address (e.g: http://www.in.tv)
if (strlen($url[0][0]) > 4) {
$result = str_replace("/", "", $url[0][0]);
return $result;
}
else
return false;
}
Thanks!
If you want a server name that can't be set by the client, use $_SERVER['SERVER_NAME']. It is set by the server itself but can also be forged under certain circumstances using a bug, as Gumbo points out and links to in the comments.
I think the one you are referring to is
$_SERVER['HTTP_HOST'];
which, given the HTTP prefix means it comes from the HTTP Headers.
You might want to use:
$_SERVER['SERVER_NAME']
which is defined by the server and can't be changed via a request?
this will get the hostname server-side, but if you're running on a commercial host (not hosting yourself), I don't imagine this will be all that useful.
$host = php_uname( 'n' );
If you're using Apache, what you should do is make your server / site only answer to certain names (else there should be a default that doesn't do much). You can do with with the ServerName and ServerAlias directives.
Edit: as pointed by Gumbo, the original poster probably means HTTP_HOST rather than HOST_NAME. Otherwise, my answer is plain wrong.
The HTTP_HOST variable reflects the domain name that the visitor used to access the site. If doesn't have anything to do with file paths! Its value is conveniently stored in $_SERVER['HTTP_HOST']. Is there any other way to get it? Of course, there're normally several ways to do things. For instance, this works when PHP runs as Apache module.
<?php
$request_headers = apache_request_headers();
echo $request_headers['Host'];
?>
The question is: why would anyone want to do such a thing? Why replace a reliable standard method with a quirky workaround that eventually fetches the same piece of data from the same place?
You have the concern that $_SERVER['HTTP_HOST'] is altered by the HTTP request. Of course it is: that's where it comes from. The browser has to specify what site it wants to visit (that's the base of name based virtual hosts) and if it sends a rogue value, well, it just won't reach the site.
Of course $_SERVER['HTTP_HOST'] can be modified by the client - because in fact IT IS sent by the client. This is part of the http protocol. If you want to get the primary server name defined in the vhost configuration of apache or whatever you can access $_SERVER['SERVER_NAME'] as proposed by the others.
I suggest it is not wise to extract the domain name from the file path of the server (which is stored in __FILE__) as it may render your application non-relocatable (it will no longer be storage location agnostic).
You may see the contents of the array by dumping it within the script using var_dump($_SERVER) but keep in mind the not all web servers and all web server settings expose the same environment. This is documented in the web server documentation and I think it is partly documented in the php online docs.
Update / Important notice: As others pointed out, the content of $_SERVER['SERVER_NAME'] could be spoofed if apache is configured for UseCanonicalName off (which may be a default setting if you are using eg Plesk-based hosting). So actually going with the __FILE__ can solve this (if your doc root contains the host name). The bigger problem of the first approach is that it can be used to inject any sort of stuff into your application (SQL, JavaScript) because php programmers usually take it granted that SERVER_NAME is no user input and thus apply no sanitizing to it.
You don't. That's the purpose of the $_SERVER variables. If you want to get the HOST_NAME from the path, you must first get the PATH from $_SERVER['HTTP_HOST']