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https://github.com/paragonie/csp-builder

Build Content-Security-Policy headers from a JSON file (or build them programmatically)
https://github.com/paragonie/csp-builder

content-security-policy cross-site-scripting csp csp-builder csp-header easy-to-use http http-header json-configuration php secure-by-default security xss

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Build Content-Security-Policy headers from a JSON file (or build them programmatically)

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# Content Security Policy Builder

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Easily integrate Content-Security-Policy headers into your web application, either
from a JSON configuration file, or programatically.

CSP Builder was created by [Paragon Initiative Enterprises](https://paragonie.com)
as part of our effort to encourage better [application security](https://paragonie.com/service/appsec) practices.

Check out our other [open source projects](https://paragonie.com/projects) too.

There's also a [CSP middleware](https://github.com/geggleto/geggleto-csp-middleware) available that uses this library.

## Installing

First, get [Composer](https://getcomposer.org/download), then run:

```sh
composer require paragonie/csp-builder
```

## Build a Content Security Policy header from a JSON configuration file

```php
sendCSPHeader();

```

You can also load the configuration from a JSON string, like so:

```php
sendCSPHeader();

```

Finally, you can just pass an array to the first argument of the constructor:

```php
sendCSPHeader();

```

### Example

```json
{
"report-only": false,
"report-to": "PolicyName",
"report-uri": "/csp_violation_reporting_endpoint",
"base-uri": [],
"default-src": [],
"child-src": {
"allow": [
"https://www.youtube.com",
"https://www.youtube-nocookie.com"
],
"self": false
},
"connect-src": [],
"font-src": {
"self": true
},
"form-action": {
"allow": [
"https://example.com"
],
"self": true
},
"frame-ancestors": [],
"img-src": {
"blob": true,
"self": true,
"data": true
},
"media-src": [],
"object-src": [],
"plugin-types": [],
"script-src": {
"allow": [
"https://www.google-analytics.com"
],
"self": true,
"unsafe-inline": false,
"unsafe-eval": false
},
"style-src": {
"self": true
},
"upgrade-insecure-requests": true
}
```

## Build a Content Security Policy, programmatically

```php
nonce('script-src');
$body .= "";
$body .= $desiredJavascriptCode;
$body .= "";

// Let's add a hash to the CSP header for $someScript
$hash = $csp->hash('script-src', $someScript, 'sha256');

// Add a new source domain to the whitelist
$csp->addSource('image', 'https://ytimg.com');

// Set the Report URI
$csp->setReportUri('https://example.com/csp_report.php');

// Let's turn on HTTPS enforcement
$csp->addDirective('upgrade-insecure-requests', true);

$csp->sendCSPHeader();
```

Note that many of these methods can be chained together:

```php
$csp = CSPBuilder::fromFile('/path/to/source.json');
$csp->addSource('image', 'https://ytimg.com')
->addSource('frame', 'https://youtube.com')
->addDirective('upgrade-insecure-requests', true)
->sendCSPHeader();
```

* `addSource()`
* `addDirective()`
* `disableOldBrowserSupport()`
* `enableOldBrowserSupport()`
* `hash()`
* `preHash()`
* `setDirective()`
* `setBlobAllowed()`
* `setDataAllowed()`
* `setFileSystemAllowed()`
* `setMediaStreamAllowed()`
* `setReportUri()`
* `setSelfAllowed()`
* `setAllowUnsafeEval()`
* `setAllowUnsafeInline()`

## Inject a CSP header into a PSR-7 message

Instead of invoking `sendCSPHeader()`, you can instead inject the headers into
your PSR-7 message object by calling it like so:

```php
/**
* $yourMessageHere is an instance of an object that implements
* \Psr\Http\Message\MessageInterface
*
* Typically, this will be a Response object that implements
* \Psr\Http\Message\ResponseInterface
*
* @ref https://github.com/guzzle/psr7/blob/master/src/Response.php
*/
$csp->injectCSPHeader($yourMessageHere);
```

## Save a CSP header for configuring Apache/nginx

Instead of calling `sendCSPHeader()` on every request, you can build the CSP once
and save it to a snippet for including in your server configuration:

```php
$policy = CSPBuilder::fromFile('/path/to/source.json');
$policy->saveSnippet(
'/etc/nginx/snippets/my-csp.conf',
CSPBuilder::FORMAT_NGINX
);
```

Make sure you reload your webserver afterwards.

## Processing output before save to disk through hook

```php
$policy = CSPBuilder::fromFile('/path/to/source.json');
$policy->saveSnippet(
'/etc/nginx/snippets/my-csp.conf',
CSPBuilder::FORMAT_NGINX
fn ($output) => \str_replace('bar','foo',$output)
);
```

The output will change before save to file

## Support Contracts

If your company uses this library in their products or services, you may be
interested in [purchasing a support contract from Paragon Initiative Enterprises](https://paragonie.com/enterprise).