How to Access-Control-Allow-Origin for multiple origin domains?

Query explained:

Is there a way to allow multiple cross-domains using the Access-Control-Allow-Origin header?

I’m aware of the *, but it is too open. I really want to allow just a couple domains.

As an example, something like this:

Access-Control-Allow-Origin: , 

I have tried the above code but it does not seem to work in Firefox.

Is it possible to specify multiple domains or am I stuck with just one?

How to allow multiple cross-domains using the Access-Control-Allow-Origin?

Sounds like the recommended way to do it is to have your server read the Origin header from the client, compare that to the list of domains you would like to allow, and if it matches, echo the value of the Origin header back to the client as the Access-Control-Allow-Origin header in the response.

With .htaccess you can do it like this:

# ----------------------------------------------------------------------
# Allow loading of external fonts
# ----------------------------------------------------------------------
<FilesMatch "\.(ttf|otf|eot|woff|woff2)$">
    <IfModule mod_headers.c>
        SetEnvIf Origin "http(s)?://(www\.)?(google.com|staging.google.com|development.google.com|otherdomain.example|dev02.otherdomain.example)$" AccessControlAllowOrigin=$0
        Header add Access-Control-Allow-Origin %{AccessControlAllowOrigin}e env=AccessControlAllowOrigin
        Header merge Vary Origin
    </IfModule>
</FilesMatch>

Solution using PHP:

Another solution I’m using in PHP:

$http_origin = $_SERVER['HTTP_ORIGIN'];

if ($http_origin == "http://www.domain1.com" || $http_origin == "http://www.domain2.com" || $http_origin == "http://www.domain3.com")
{  
    header("Access-Control-Allow-Origin: $http_origin");
}

Answer #3:

This worked for me:

SetEnvIf Origin "^http(s)?://(.+\.)?(domain\.example|domain2\.example)$" origin_is=$0 
Header always set Access-Control-Allow-Origin %{origin_is}e env=origin_is

When put in .htaccess, it will work for sure.

Answer #4:

I had the same problem with woff-fonts, multiple subdomains had to have access. To allow subdomains I added something like this to my httpd.conf:

SetEnvIf Origin "^(.*\.example\.com)$" ORIGIN_SUB_DOMAIN=$1
<FilesMatch "\.woff$">
    Header set Access-Control-Allow-Origin "%{ORIGIN_SUB_DOMAIN}e" env=ORIGIN_SUB_DOMAIN
</FilesMatch>

For multiple domains you could just change the regex in SetEnvIf.

Answer #5:

Here’s how to echo the Origin header back if it matches your domain with Nginx, this is useful if you want to serve a font multiple sub-domains:

location /fonts {
    # this will echo back the origin header
    if ($http_origin ~ "example.org$") {
        add_header "Access-Control-Allow-Origin" $http_origin;
    }
}

Answer #6:

Here is what i did for a PHP application which is being requested by AJAX

$request_headers        = apache_request_headers();
$http_origin            = $request_headers['Origin'];
$allowed_http_origins   = array(
                            "http://myDumbDomain.example"   ,
                            "http://anotherDumbDomain.example"  ,
                            "http://localhost"  ,
                          );
if (in_array($http_origin, $allowed_http_origins)){  
    @header("Access-Control-Allow-Origin: " . $http_origin);
}

If the requesting origin is allowed by my server, return the $http_origin itself as value of the Access-Control-Allow-Origin header instead of returning a * wildcard.

Answer #7:

For ExpressJS applications you can use:

app.use((req, res, next) => {
    const corsWhitelist = [
        'https://domain1.example',
        'https://domain2.example',
        'https://domain3.example'
    ];
    if (corsWhitelist.indexOf(req.headers.origin) !== -1) {
        res.header('Access-Control-Allow-Origin', req.headers.origin);
        res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
    }

    next();
});

Answer #8:

There is one disadvantage you should be aware of: As soon as you out-source files to a CDN (or any other server which doesn’t allow scripting) or if your files are cached on a proxy, altering response based on ‘Origin’ request header will not work.

Answer #9:

For Nginx users to allow CORS for multiple domains. I like the @marshall’s example although his anwers only matches one domain. To match a list of domain and subdomain this regex make it ease to work with fonts:

location ~* \.(?:ttf|ttc|otf|eot|woff|woff2)$ {
   if ( $http_origin ~* (https?://(.+\.)?(domain1|domain2|domain3)\.(?:me|co|com)$) ) {
      add_header "Access-Control-Allow-Origin" "$http_origin";
   }
}

This will only echo “Access-Control-Allow-Origin” headers that matches with the given list of domains.

Answer #10:

For multiple domains, in your .htaccess:

<IfModule mod_headers.c>
    SetEnvIf Origin "http(s)?://(www\.)?(domain1.example|domain2.example)$" AccessControlAllowOrigin=$0$1
    Header add Access-Control-Allow-Origin %{AccessControlAllowOrigin}e env=AccessControlAllowOrigin
    Header set Access-Control-Allow-Credentials true
</IfModule>

Answer #11:

As mentioned above, Access-Control-Allow-Origin should be unique and Vary should be set to Origin if you are behind a CDN (Content Delivery Network).

Relevant part of my Nginx configuration:

if ($http_origin ~* (https?://.*\.mydomain.example(:[0-9]+)?)) {
  set $cors "true";
}
if ($cors = "true") {
  add_header 'Access-Control-Allow-Origin' "$http_origin";
  add_header 'X-Frame-Options' "ALLOW FROM $http_origin";
  add_header 'Access-Control-Allow-Credentials' 'true';
  add_header 'Vary' 'Origin';
}

Hope you learned something from this post.

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Linux and Python enthusiast, in love with open source since 2014, Writer at programming-articles.com, India.

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