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require 'erb'
require 'active_support/core_ext/kernel/singleton_class'
require 'active_support/deprecation'
class ERB
module Util
HTML_ESCAPE = { '&' => '&amp;', '>' => '&gt;', '<' => '&lt;', '"' => '&quot;', "'" => '&#39;' }
JSON_ESCAPE = { '&' => '\u0026', '>' => '\u003e', '<' => '\u003c', "\u2028" => '\u2028', "\u2029" => '\u2029' }
HTML_ESCAPE_REGEXP = /[&"'><]/
HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+)|(#[xX][\dA-Fa-f]+));)/
JSON_ESCAPE_REGEXP = /[\u2028\u2029&><]/u
# A utility method for escaping HTML tag characters.
# This method is also aliased as <tt>h</tt>.
#
# In your ERB templates, use this method to escape any unsafe content. For example:
# <%=h @person.name %>
#
# puts html_escape('is a > 0 & a < 10?')
# # => is a &gt; 0 &amp; a &lt; 10?
def html_escape(s)
unwrapped_html_escape(s).html_safe
end
# Aliasing twice issues a warning "discarding old...". Remove first to avoid it.
remove_method(:h)
alias h html_escape
module_function :h
singleton_class.send(:remove_method, :html_escape)
module_function :html_escape
# HTML escapes strings but doesn't wrap them with an ActiveSupport::SafeBuffer.
# This method is not for public consumption! Seriously!
def unwrapped_html_escape(s) # :nodoc:
s = s.to_s
if s.html_safe?
s
else
s.gsub(HTML_ESCAPE_REGEXP, HTML_ESCAPE)
end
end
module_function :unwrapped_html_escape
# A utility method for escaping HTML without affecting existing escaped entities.
#
# html_escape_once('1 < 2 &amp; 3')
# # => "1 &lt; 2 &amp; 3"
#
# html_escape_once('&lt;&lt; Accept & Checkout')
# # => "&lt;&lt; Accept &amp; Checkout"
def html_escape_once(s)
result = s.to_s.gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE)
s.html_safe? ? result.html_safe : result
end
module_function :html_escape_once
# A utility method for escaping HTML entities in JSON strings. Specifically, the
# &, > and < characters are replaced with their equivalent unicode escaped form -
# \u0026, \u003e, and \u003c. The Unicode sequences \u2028 and \u2029 are also
# escaped as they are treated as newline characters in some JavaScript engines.
# These sequences have identical meaning as the original characters inside the
# context of a JSON string, so assuming the input is a valid and well-formed
# JSON value, the output will have equivalent meaning when parsed:
#
# json = JSON.generate({ name: "</script><script>alert('PWNED!!!')</script>"})
# # => "{\"name\":\"</script><script>alert('PWNED!!!')</script>\"}"
#
# json_escape(json)
# # => "{\"name\":\"\\u003C/script\\u003E\\u003Cscript\\u003Ealert('PWNED!!!')\\u003C/script\\u003E\"}"
#
# JSON.parse(json) == JSON.parse(json_escape(json))
# # => true
#
# The intended use case for this method is to escape JSON strings before including
# them inside a script tag to avoid XSS vulnerability:
#
# <script>
# var currentUser = <%= raw json_escape(current_user.to_json) %>;
# </script>
#
# It is necessary to +raw+ the result of +json_escape+, so that quotation marks
# don't get converted to <tt>&quot;</tt> entities. +json_escape+ doesn't
# automatically flag the result as HTML safe, since the raw value is unsafe to
# use inside HTML attributes.
#
# If you need to output JSON elsewhere in your HTML, you can just do something
# like this, as any unsafe characters (including quotation marks) will be
# automatically escaped for you:
#
# <div data-user-info="<%= current_user.to_json %>">...</div>
#
# WARNING: this helper only works with valid JSON. Using this on non-JSON values
# will open up serious XSS vulnerabilities. For example, if you replace the
# +current_user.to_json+ in the example above with user input instead, the browser
# will happily eval() that string as JavaScript.
#
# The escaping performed in this method is identical to those performed in the
# Active Support JSON encoder when +ActiveSupport.escape_html_entities_in_json+ is
# set to true. Because this transformation is idempotent, this helper can be
# applied even if +ActiveSupport.escape_html_entities_in_json+ is already true.
#
# Therefore, when you are unsure if +ActiveSupport.escape_html_entities_in_json+
# is enabled, or if you are unsure where your JSON string originated from, it
# is recommended that you always apply this helper (other libraries, such as the
# JSON gem, do not provide this kind of protection by default; also some gems
# might override +to_json+ to bypass Active Support's encoder).
def json_escape(s)
result = s.to_s.gsub(JSON_ESCAPE_REGEXP, JSON_ESCAPE)
s.html_safe? ? result.html_safe : result
end
module_function :json_escape
end
end
class Object
def html_safe?
false
end
end
class Numeric
def html_safe?
true
end
end
module ActiveSupport #:nodoc:
class SafeBuffer < String
UNSAFE_STRING_METHODS = %w(
capitalize chomp chop delete downcase gsub lstrip next reverse rstrip
slice squeeze strip sub succ swapcase tr tr_s upcase
)
alias_method :original_concat, :concat
private :original_concat
class SafeConcatError < StandardError
def initialize
super 'Could not concatenate to the buffer because it is not html safe.'
end
end
def [](*args)
if args.size < 2
super
else
if html_safe?
new_safe_buffer = super
new_safe_buffer.instance_eval { @html_safe = true }
new_safe_buffer
else
to_str[*args]
end
end
end
def safe_concat(value)
raise SafeConcatError unless html_safe?
original_concat(value)
end
def initialize(*)
@html_safe = true
super
end
def initialize_copy(other)
super
@html_safe = other.html_safe?
end
def clone_empty
self[0, 0]
end
def concat(value)
super(html_escape_interpolated_argument(value))
end
alias << concat
def prepend(value)
super(html_escape_interpolated_argument(value))
end
def prepend!(value)
ActiveSupport::Deprecation.deprecation_warning "ActiveSupport::SafeBuffer#prepend!", :prepend
prepend value
end
def +(other)
dup.concat(other)
end
def %(args)
case args
when Hash
escaped_args = Hash[args.map { |k,arg| [k, html_escape_interpolated_argument(arg)] }]
else
escaped_args = Array(args).map { |arg| html_escape_interpolated_argument(arg) }
end
self.class.new(super(escaped_args))
end
def html_safe?
defined?(@html_safe) && @html_safe
end
def to_s
self
end
def to_param
to_str
end
def encode_with(coder)
coder.represent_scalar nil, to_str
end
UNSAFE_STRING_METHODS.each do |unsafe_method|
if unsafe_method.respond_to?(unsafe_method)
class_eval <<-EOT, __FILE__, __LINE__ + 1
def #{unsafe_method}(*args, &block) # def capitalize(*args, &block)
to_str.#{unsafe_method}(*args, &block) # to_str.capitalize(*args, &block)
end # end
def #{unsafe_method}!(*args) # def capitalize!(*args)
@html_safe = false # @html_safe = false
super # super
end # end
EOT
end
end
private
def html_escape_interpolated_argument(arg)
(!html_safe? || arg.html_safe?) ? arg :
arg.to_s.gsub(ERB::Util::HTML_ESCAPE_REGEXP, ERB::Util::HTML_ESCAPE)
end
end
end
class String
def html_safe
ActiveSupport::SafeBuffer.new(self)
end
end
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