ikarienator / salvation

Parse Content Security Policy headers, warn about policy errors, safely manipulate, render, and optimise policies

salvation

This is a general purpose library for working with Content Security Policy policies.

• parse CSP policies into an easy-to-use representation
• ask questions about what a CSP policy allows or restricts
• warn about nonsensical CSP policies and deprecated or nonstandard features
• safely create, manipulate, and merge CSP policies
• render and optimise CSP policies

Install

mvn install

Create a Policy

Parse a policy using one of the Parser.parse static methods. An Origin or String may be given as the origin. The third parameter, if given, will be populated with warnings.

List<Warning> warnings = new ArrayList();
Origin origin = URI.parse("http://example.com");
String policyText = "...";
Policy p = Parser.parse(policyText, origin, warnings);

To include location information, use ParserWithLocation.parse in place of Parser.parse.

A policy may also be created using the Policy constructor and populated using the addDirective method.

Origin origin = URI.parse("http://example.com");
Policy p = new Policy(origin);
Set<SourceExpression> scriptSourceValues = new HashSet<>();
scriptSourceValues.add(new None());
p.addDirective(new ScriptSrcDirective(scriptSourceValues));

Query a Policy

Policy p = Parser.parse("script-src a; default-src b", "http://example.com");
p.allowsScriptFromSource(Uri.parse("a")); // true
p.allowsScriptFromSource(Uri.parse("b")); // false
p.allowsStyleFromSource(Uri.parse("b")); // true