discourse/lib/content_security_policy/builder.rb

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# frozen_string_literal: true
require 'content_security_policy/default'
class ContentSecurityPolicy
class Builder
EXTENDABLE_DIRECTIVES = %i[
base_uri
frame_ancestors
manifest_src
object_src
script_src
worker_src
].freeze
# Make extending these directives no-op, until core includes them in default CSP
TO_BE_EXTENDABLE = %i[
connect_src
default_src
font_src
form_action
frame_src
img_src
media_src
prefetch_src
style_src
].freeze
def initialize(base_url:)
@directives = Default.new(base_url: base_url).directives
@base_url = base_url
end
def <<(extension)
return unless valid_extension?(extension)
extension.each { |directive, sources| extend_directive(normalize_directive(directive), sources) }
end
def build
policy = ActionDispatch::ContentSecurityPolicy.new
@directives.each do |directive, sources|
if sources.is_a?(Array)
policy.public_send(directive, *sources)
else
policy.public_send(directive, sources)
end
end
policy.build
end
private
def normalize_directive(directive)
directive.to_s.gsub('-', '_').to_sym
end
def normalize_source(source)
if source.starts_with?("/")
"#{@base_url}#{source}"
else
source
end
rescue URI::ParseError
source
end
def extend_directive(directive, sources)
return unless extendable?(directive)
@directives[directive] ||= []
sources = Array(sources).map { |s| normalize_source(s) }
@directives[directive].concat(sources)
@directives[directive].delete(:none) if @directives[directive].count > 1
end
def extendable?(directive)
EXTENDABLE_DIRECTIVES.include?(directive)
end
def valid_extension?(extension)
extension.is_a?(Hash)
end
end
end