lib/rack/utils.rb

# -*- encoding: binary -*-
require 'fileutils'
require 'set'
require 'tempfile'
require 'rack/multipart'

major, minor, patch = RUBY_VERSION.split('.').map { |v| v.to_i }

if major == 1 && minor < 9
  require 'rack/backports/uri/common_18'
elsif major == 1 && minor == 9 && patch < 3
  require 'rack/backports/uri/common_192'
else
  require 'uri/common'
end

module Rack
  # Rack::Utils contains a grab-bag of useful methods for writing web
  # applications adopted from all kinds of Ruby libraries.

  module Utils
    # URI escapes. (CGI style space to +)
    def escape(s)
      URI.encode_www_form_component(s)
    end
    module_function :escape

    # Like URI escaping, but with %20 instead of +. Strictly speaking this is
    # true URI escaping.
    def escape_path(s)
      escape(s).gsub('+', '%20')
    end
    module_function :escape_path

    # Unescapes a URI escaped string with +encoding+. +encoding+ will be the
    # target encoding of the string returned, and it defaults to UTF-8
    if defined?(::Encoding)
      def unescape(s, encoding = Encoding::UTF_8)
        URI.decode_www_form_component(s, encoding)
      end
    else
      def unescape(s, encoding = nil)
        URI.decode_www_form_component(s, encoding)
      end
    end
    module_function :unescape

    DEFAULT_SEP = /[&;] */n

    class << self
      attr_accessor :key_space_limit
    end

    # The default number of bytes to allow parameter keys to take up.
    # This helps prevent a rogue client from flooding a Request.
    self.key_space_limit = 65536

    # Stolen from Mongrel, with some small modifications:
    # Parses a query string by breaking it up at the '&'
    # and ';' characters.  You can also use this to parse
    # cookies by changing the characters used in the second
    # parameter (which defaults to '&;').
    def parse_query(qs, d = nil)
      params = KeySpaceConstrainedParams.new

      (qs || '').split(d ? /[#{d}] */n : DEFAULT_SEP).each do |p|
        k, v = p.split('=', 2).map { |x| unescape(x) }

        if cur = params[k]
          if cur.class == Array
            params[k] << v
          else
            params[k] = [cur, v]
          end
        else
          params[k] = v
        end
      end

      return params.to_params_hash
    end
    module_function :parse_query

    def parse_nested_query(qs, d = nil)
      params = KeySpaceConstrainedParams.new

      (qs || '').split(d ? /[#{d}] */n : DEFAULT_SEP).each do |p|
        k, v = p.split('=', 2).map { |s| unescape(s) }

        normalize_params(params, k, v)
      end

      return params.to_params_hash
    end
    module_function :parse_nested_query

    def normalize_params(params, name, v = nil)
      name =~ %r(\A[\[\]]*([^\[\]]+)\]*)
      k = $1 || ''
      after = $' || ''

      return if k.empty?

      if after == ""
        params[k] = v
      elsif after == "[]"
        params[k] ||= []
        raise TypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        params[k] << v
      elsif after =~ %r(^\[\]\[([^\[\]]+)\]$) || after =~ %r(^\[\](.+)$)
        child_key = $1
        params[k] ||= []
        raise TypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        if params_hash_type?(params[k].last) && !params[k].last.key?(child_key)
          normalize_params(params[k].last, child_key, v)
        else
          params[k] << normalize_params(params.class.new, child_key, v)
        end
      else
        params[k] ||= params.class.new
        raise TypeError, "expected Hash (got #{params[k].class.name}) for param `#{k}'" unless params_hash_type?(params[k])
        params[k] = normalize_params(params[k], after, v)
      end

      return params
    end
    module_function :normalize_params

    def params_hash_type?(obj)
      obj.kind_of?(KeySpaceConstrainedParams) || obj.kind_of?(Hash)
    end
    module_function :params_hash_type?

    def build_query(params)
      params.map { |k, v|
        if v.class == Array
          build_query(v.map { |x| [k, x] })
        else
          v.nil? ? escape(k) : "#{escape(k)}=#{escape(v)}"
        end
      }.join("&")
    end
    module_function :build_query

    def build_nested_query(value, prefix = nil)
      case value
      when Array
        value.map { |v|
          build_nested_query(v, "#{prefix}[]")
        }.join("&")
      when Hash
        value.map { |k, v|
          build_nested_query(v, prefix ? "#{prefix}[#{escape(k)}]" : escape(k))
        }.join("&")
      when String
        raise ArgumentError, "value must be a Hash" if prefix.nil?
        "#{prefix}=#{escape(value)}"
      else
        prefix
      end
    end
    module_function :build_nested_query

    ESCAPE_HTML = {
      "&" => "&amp;",
      "<" => "&lt;",
      ">" => "&gt;",
      "'" => "&#x27;",
      '"' => "&quot;",
      "/" => "&#x2F;"
    }
    if //.respond_to?(:encoding)
      ESCAPE_HTML_PATTERN = Regexp.union(*ESCAPE_HTML.keys)
    else
      # On 1.8, there is a kcode = 'u' bug that allows for XSS otherwhise
      # TODO doesn't apply to jruby, so a better condition above might be preferable?
      ESCAPE_HTML_PATTERN = /#{Regexp.union(*ESCAPE_HTML.keys)}/n
    end

    # Escape ampersands, brackets and quotes to their HTML/XML entities.
    def escape_html(string)
      string.to_s.gsub(ESCAPE_HTML_PATTERN){|c| ESCAPE_HTML[c] }
    end
    module_function :escape_html

    def select_best_encoding(available_encodings, accept_encoding)
      # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

      expanded_accept_encoding =
        accept_encoding.map { |m, q|
          if m == "*"
            (available_encodings - accept_encoding.map { |m2, _| m2 }).map { |m2| [m2, q] }
          else
            [[m, q]]
          end
        }.inject([]) { |mem, list|
          mem + list
        }

      encoding_candidates = expanded_accept_encoding.sort_by { |_, q| -q }.map { |m, _| m }

      unless encoding_candidates.include?("identity")
        encoding_candidates.push("identity")
      end

      expanded_accept_encoding.find_all { |m, q|
        q == 0.0
      }.each { |m, _|
        encoding_candidates.delete(m)
      }

      return (encoding_candidates & available_encodings)[0]
    end
    module_function :select_best_encoding

    def set_cookie_header!(header, key, value)
      case value
      when Hash
        domain  = "; domain="  + value[:domain] if value[:domain]
        path    = "; path="    + value[:path]   if value[:path]
        # According to RFC 2109, we need dashes here.
        # N.B.: cgi.rb uses spaces...
        expires = "; expires=" +
          rfc2822(value[:expires].clone.gmtime) if value[:expires]
        secure = "; secure"  if value[:secure]
        httponly = "; HttpOnly" if value[:httponly]
        value = value[:value]
      end
      value = [value] unless Array === value
      cookie = escape(key) + "=" +
        value.map { |v| escape v }.join("&") +
        "#{domain}#{path}#{expires}#{secure}#{httponly}"

      case header["Set-Cookie"]
      when nil, ''
        header["Set-Cookie"] = cookie
      when String
        header["Set-Cookie"] = [header["Set-Cookie"], cookie].join("\n")
      when Array
        header["Set-Cookie"] = (header["Set-Cookie"] + [cookie]).join("\n")
      end

      nil
    end
    module_function :set_cookie_header!

    def delete_cookie_header!(header, key, value = {})
      case header["Set-Cookie"]
      when nil, ''
        cookies = []
      when String
        cookies = header["Set-Cookie"].split("\n")
      when Array
        cookies = header["Set-Cookie"]
      end

      cookies.reject! { |cookie|
        if value[:domain]
          cookie =~ /\A#{escape(key)}=.*domain=#{value[:domain]}/
        elsif value[:path]
          cookie =~ /\A#{escape(key)}=.*path=#{value[:path]}/
        else
          cookie =~ /\A#{escape(key)}=/
        end
      }

      header["Set-Cookie"] = cookies.join("\n")

      set_cookie_header!(header, key,
                 {:value => '', :path => nil, :domain => nil,
                   :expires => Time.at(0) }.merge(value))

      nil
    end
    module_function :delete_cookie_header!

    # Return the bytesize of String; uses String#size under Ruby 1.8 and
    # String#bytesize under 1.9.
    if ''.respond_to?(:bytesize)
      def bytesize(string)
        string.bytesize
      end
    else
      def bytesize(string)
        string.size
      end
    end
    module_function :bytesize

    # Modified version of stdlib time.rb Time#rfc2822 to use '%d-%b-%Y' instead
    # of '% %b %Y'.
    # It assumes that the time is in GMT to comply to the RFC 2109.
    #
    # NOTE: I'm not sure the RFC says it requires GMT, but is ambigous enough
    # that I'm certain someone implemented only that option.
    # Do not use %a and %b from Time.strptime, it would use localized names for
    # weekday and month.
    #
    def rfc2822(time)
      wday = Time::RFC2822_DAY_NAME[time.wday]
      mon = Time::RFC2822_MONTH_NAME[time.mon - 1]
      time.strftime("#{wday}, %d-#{mon}-%Y %H:%M:%S GMT")
    end
    module_function :rfc2822

    # Parses the "Range:" header, if present, into an array of Range objects.
    # Returns nil if the header is missing or syntactically invalid.
    # Returns an empty array if none of the ranges are satisfiable.
    def byte_ranges(env, size)
      # See <http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35>
      http_range = env['HTTP_RANGE']
      return nil unless http_range
      ranges = []
      http_range.split(/,\s*/).each do |range_spec|
        matches = range_spec.match(/bytes=(\d*)-(\d*)/)
        return nil  unless matches
        r0,r1 = matches[1], matches[2]
        if r0.empty?
          return nil  if r1.empty?
          # suffix-byte-range-spec, represents trailing suffix of file
          r0 = [size - r1.to_i, 0].max
          r1 = size - 1
        else
          r0 = r0.to_i
          if r1.empty?
            r1 = size - 1
          else
            r1 = r1.to_i
            return nil  if r1 < r0  # backwards range is syntactically invalid
            r1 = size-1  if r1 >= size
          end
        end
        ranges << (r0..r1)  if r0 <= r1
      end
      ranges
    end
    module_function :byte_ranges

    # Context allows the use of a compatible middleware at different points
    # in a request handling stack. A compatible middleware must define
    # #context which should take the arguments env and app. The first of which
    # would be the request environment. The second of which would be the rack
    # application that the request would be forwarded to.
    class Context
      attr_reader :for, :app

      def initialize(app_f, app_r)
        raise 'running context does not respond to #context' unless app_f.respond_to? :context
        @for, @app = app_f, app_r
      end

      def call(env)
        @for.context(env, @app)
      end

      def recontext(app)
        self.class.new(@for, app)
      end

      def context(env, app=@app)
        recontext(app).call(env)
      end
    end

    # A case-insensitive Hash that preserves the original case of a
    # header when set.
    class HeaderHash < Hash
      def self.new(hash={})
        HeaderHash === hash ? hash : super(hash)
      end

      def initialize(hash={})
        super()
        @names = {}
        hash.each { |k, v| self[k] = v }
      end

      def each
        super do |k, v|
          yield(k, v.respond_to?(:to_ary) ? v.to_ary.join("\n") : v)
        end
      end

      def to_hash
        hash = {}
        each { |k,v| hash[k] = v }
        hash
      end

      def [](k)
        super(k) || super(@names[k.downcase])
      end

      def []=(k, v)
        canonical = k.downcase
        delete k if @names[canonical] && @names[canonical] != k # .delete is expensive, don't invoke it unless necessary
        @names[k] = @names[canonical] = k
        super k, v
      end

      def delete(k)
        canonical = k.downcase
        result = super @names.delete(canonical)
        @names.delete_if { |name,| name.downcase == canonical }
        result
      end

      def include?(k)
        @names.include?(k) || @names.include?(k.downcase)
      end

      alias_method :has_key?, :include?
      alias_method :member?, :include?
      alias_method :key?, :include?

      def merge!(other)
        other.each { |k, v| self[k] = v }
        self
      end

      def merge(other)
        hash = dup
        hash.merge! other
      end

      def replace(other)
        clear
        other.each { |k, v| self[k] = v }
        self
      end
    end

    class KeySpaceConstrainedParams
      def initialize(limit = Utils.key_space_limit)
        @limit  = limit
        @size   = 0
        @params = {}
      end

      def [](key)
        @params[key]
      end

      def []=(key, value)
        @size += key.size unless @params.key?(key)
        raise RangeError, 'exceeded available parameter key space' if @size > @limit
        @params[key] = value
      end

      def key?(key)
        @params.key?(key)
      end

      def to_params_hash
        hash = @params
        hash.keys.each do |key|
          value = hash[key]
          if value.kind_of?(self.class)
            hash[key] = value.to_params_hash
          elsif value.kind_of?(Array)
            value.map! {|x| x.kind_of?(self.class) ? x.to_params_hash : x}
          end
        end
        hash
      end
    end

    # Every standard HTTP code mapped to the appropriate message.
    # Generated with:
    #   curl -s http://www.iana.org/assignments/http-status-codes | \
    #     ruby -ane 'm = /^(\d{3}) +(\S[^\[(]+)/.match($_) and
    #                puts "      #{m[1]}  => \x27#{m[2].strip}x27,"'
    HTTP_STATUS_CODES = {
      100  => 'Continue',
      101  => 'Switching Protocols',
      102  => 'Processing',
      200  => 'OK',
      201  => 'Created',
      202  => 'Accepted',
      203  => 'Non-Authoritative Information',
      204  => 'No Content',
      205  => 'Reset Content',
      206  => 'Partial Content',
      207  => 'Multi-Status',
      226  => 'IM Used',
      300  => 'Multiple Choices',
      301  => 'Moved Permanently',
      302  => 'Found',
      303  => 'See Other',
      304  => 'Not Modified',
      305  => 'Use Proxy',
      306  => 'Reserved',
      307  => 'Temporary Redirect',
      400  => 'Bad Request',
      401  => 'Unauthorized',
      402  => 'Payment Required',
      403  => 'Forbidden',
      404  => 'Not Found',
      405  => 'Method Not Allowed',
      406  => 'Not Acceptable',
      407  => 'Proxy Authentication Required',
      408  => 'Request Timeout',
      409  => 'Conflict',
      410  => 'Gone',
      411  => 'Length Required',
      412  => 'Precondition Failed',
      413  => 'Request Entity Too Large',
      414  => 'Request-URI Too Long',
      415  => 'Unsupported Media Type',
      416  => 'Requested Range Not Satisfiable',
      417  => 'Expectation Failed',
      418  => "I'm a Teapot",
      422  => 'Unprocessable Entity',
      423  => 'Locked',
      424  => 'Failed Dependency',
      426  => 'Upgrade Required',
      500  => 'Internal Server Error',
      501  => 'Not Implemented',
      502  => 'Bad Gateway',
      503  => 'Service Unavailable',
      504  => 'Gateway Timeout',
      505  => 'HTTP Version Not Supported',
      506  => 'Variant Also Negotiates',
      507  => 'Insufficient Storage',
      510  => 'Not Extended',
    }

    # Responses with HTTP status codes that should not have an entity body
    STATUS_WITH_NO_ENTITY_BODY = Set.new((100..199).to_a << 204 << 205 << 304)

    SYMBOL_TO_STATUS_CODE = Hash[*HTTP_STATUS_CODES.map { |code, message|
      [message.downcase.gsub(/\s|-/, '_').to_sym, code]
    }.flatten]

    def status_code(status)
      if status.is_a?(Symbol)
        SYMBOL_TO_STATUS_CODE[status] || 500
      else
        status.to_i
      end
    end
    module_function :status_code

    Multipart = Rack::Multipart

  end
end