Content-Security-Policy in head?

[OutsourcedGuru]

The Mozilla documentation describes something called a Content-Security-Policy which is becoming more used in websites, especially those which serve up pages to smartphones.

From personal experience, they're a pain.

The Cordova (Adobe PhotoGap) documentation included this.

Here are some example CSP declarations for your `.html` pages:

    <!-- Good default declaration:
        * gap: is required only on iOS (when using UIWebView) and is needed for JS->native communication
        * https://ssl.gstatic.com is required only on Android and is needed for TalkBack to function properly
        * Disables use of eval() and inline scripts in order to mitigate risk of XSS vulnerabilities. To change this:
            * Enable inline JS: add 'unsafe-inline' to default-src
            * Enable eval(): add 'unsafe-eval' to default-src
    -->
    <meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com; style-src 'self' 'unsafe-inline'; media-src *">

    <!-- Allow everything but only from the same origin and foo.com -->
    <meta http-equiv="Content-Security-Policy" content="default-src 'self' foo.com">

    <!-- This policy allows everything (eg CSS, AJAX, object, frame, media, etc) except that 
        * CSS only from the same origin and inline styles,
        * scripts only from the same origin and inline styles, and eval()
    -->
    <meta http-equiv="Content-Security-Policy" content="default-src *; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline' 'unsafe-eval'">

    <!-- Allows XHRs only over HTTPS on the same domain. -->
    <meta http-equiv="Content-Security-Policy" content="default-src 'self' https:">

    <!-- Allow iframe to https://cordova.apache.org/ -->
    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; frame-src 'self' https://cordova.apache.org">

I've noticed that my own websites will happily work on a standard browser (Safari on macOS). But then you try the same thing from an iOS or Android device and suddenly they're getting all paranoid about the same things you did before. There will be some kind of terse error in the console log which boils down to either no CSP or it doesn't like it somehow.