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<title>module Rack::Utils - rack-2.2.23 Documentation</title>

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<div id="class-metadata">
 
 
 
 
 
<div id="method-list-section" class="nav-section">
 <h3>Methods</h3>

<ul class="link-list" role="directory">
 
 <li ><a href="#method-c-key_space_limit">::key_space_limit</a>
 
 <li ><a href="#method-c-key_space_limit-3D">::key_space_limit=</a>
 
 <li ><a href="#method-c-param_depth_limit">::param_depth_limit</a>
 
 <li ><a href="#method-c-param_depth_limit-3D">::param_depth_limit=</a>
 
 <li ><a href="#method-i-add_cookie_to_header">#add_cookie_to_header</a>
 
 <li ><a href="#method-i-add_remove_cookie_to_header">#add_remove_cookie_to_header</a>
 
 <li ><a href="#method-i-best_q_match">#best_q_match</a>
 
 <li ><a href="#method-i-build_nested_query">#build_nested_query</a>
 
 <li ><a href="#method-i-build_query">#build_query</a>
 
 <li ><a href="#method-i-byte_ranges">#byte_ranges</a>
 
 <li ><a href="#method-i-clean_path_info">#clean_path_info</a>
 
 <li ><a href="#method-i-clock_time">#clock_time</a>
 
 <li ><a href="#method-i-delete_cookie_header-21">#delete_cookie_header!</a>
 
 <li ><a href="#method-i-escape">#escape</a>
 
 <li ><a href="#method-i-escape_html">#escape_html</a>
 
 <li ><a href="#method-i-escape_path">#escape_path</a>
 
 <li ><a href="#method-i-get_byte_ranges">#get_byte_ranges</a>
 
 <li ><a href="#method-i-make_delete_cookie_header">#make_delete_cookie_header</a>
 
 <li ><a href="#method-i-parse_cookies">#parse_cookies</a>
 
 <li ><a href="#method-i-parse_cookies_header">#parse_cookies_header</a>
 
 <li ><a href="#method-i-parse_nested_query">#parse_nested_query</a>
 
 <li ><a href="#method-i-parse_query">#parse_query</a>
 
 <li ><a href="#method-i-q_values">#q_values</a>
 
 <li ><a href="#method-i-rfc2109">#rfc2109</a>
 
 <li ><a href="#method-i-rfc2822">#rfc2822</a>
 
 <li ><a href="#method-i-secure_compare">#secure_compare</a>
 
 <li ><a href="#method-i-select_best_encoding">#select_best_encoding</a>
 
 <li ><a href="#method-i-set_cookie_header-21">#set_cookie_header!</a>
 
 <li ><a href="#method-i-status_code">#status_code</a>
 
 <li ><a href="#method-i-unescape">#unescape</a>
 
 <li ><a href="#method-i-unescape_path">#unescape_path</a>
 
 <li ><a href="#method-i-valid_path-3F">#valid_path?</a>
 
 </ul>
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<main role="main" aria-labelledby="module-Rack::Utils">
 <h1 id="module-Rack::Utils" class="module">
 module Rack::Utils
 </h1>

<section class="description">
 
<a href="Utils.html"><code>Rack::Utils</code></a> contains a grab-bag of useful methods for writing web applications adopted from all kinds of Ruby libraries.

</section>

<section class="constants-list">
 <header>
 <h3>Constants</h3>
 </header>
 <dl>
 
 <dt id="COMMON_SEP">COMMON_SEP
 
 <dd>
 
 
 <dt id="DEFAULT_SEP">DEFAULT_SEP
 
 <dd>
 
 
 <dt id="ESCAPE_HTML">ESCAPE_HTML
 
 <dd>
 
 
 <dt id="ESCAPE_HTML_PATTERN">ESCAPE_HTML_PATTERN
 
 <dd>
 
 
 <dt id="HTTP_STATUS_CODES">HTTP_STATUS_CODES
 
 <dd>Every standard HTTP code mapped to the appropriate message. Generated with:

<pre>curl -s https://www.iana.org/assignments/http-status-codes/http-status-codes-1.csv | \
 ruby -ne &#39;m = /^(\d{3}),(?!Unassigned|$Unused$)([^,]+)/.match($_) and \
 puts &quot;#{m[1]} =&gt; \x27#{m[2].strip}\x27,&quot;&#39;</pre>
 
 
 <dt id="InvalidParameterError">InvalidParameterError
 
 <dd>
 
 
 <dt id="KeySpaceConstrainedParams">KeySpaceConstrainedParams
 
 <dd>
 
 
 <dt id="NULL_BYTE">NULL_BYTE
 
 <dd>
 
 
 <dt id="PATH_SEPS">PATH_SEPS
 
 <dd>
 
 
 <dt id="ParameterTypeError">ParameterTypeError
 
 <dd>
 
 
 <dt id="RFC2396_PARSER">RFC2396_PARSER
 
 <dd>
 
 
 <dt id="RFC2822_DAY_NAME">RFC2822_DAY_NAME
 
 <dd>
 
 
 <dt id="RFC2822_MONTH_NAME">RFC2822_MONTH_NAME
 
 <dd>
 
 
 <dt id="STATUS_WITH_NO_ENTITY_BODY">STATUS_WITH_NO_ENTITY_BODY
 
 <dd>Responses with HTTP status codes that should not have an entity body
 
 
 <dt id="SYMBOL_TO_STATUS_CODE">SYMBOL_TO_STATUS_CODE
 
 <dd>
 
 
 </dl>
 </section>

<section class="attribute-method-details" class="method-section">
 <header>
 <h3>Attributes</h3>
 </header>

<div id="attribute-c-default_query_parser" class="method-detail">
 <div class="method-heading attribute-method-heading">
 default_query_parser[RW]
 </div>

<div class="method-description">
 
 
 
 </div>
 </div>
 
 <div id="attribute-c-multipart_file_limit" class="method-detail">
 <div class="method-heading attribute-method-heading">
 multipart_file_limit[RW]
 </div>

<div class="method-description">
 
 
 
 </div>
 </div>
 
 <div id="attribute-c-multipart_part_limit" class="method-detail">
 <div class="method-heading attribute-method-heading">
 multipart_part_limit[RW]
 </div>

<div class="method-description">
 
 
 
 </div>
 </div>
 
 <div id="attribute-c-multipart_part_limit-3D" class="method-detail">
 <div class="method-heading attribute-method-heading">
 multipart_part_limit=[RW]
 </div>

<div class="method-description">
 
 
 
 </div>
 </div>
 
 <div id="attribute-c-multipart_total_part_limit" class="method-detail">
 <div class="method-heading attribute-method-heading">
 multipart_total_part_limit[RW]
 </div>

<section id="public-class-5Buntitled-5D-method-details" class="method-section">
 <header>
 <h3>Public Class Methods</h3>
 </header>

<div id="method-c-key_space_limit" class="method-detail ">
 
 <div class="method-heading">
 key_space_limit()
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="key_space_limit-source">
 <pre># File lib/rack/utils.rb, line 88
def self.key_space_limit
 default_query_parser.key_space_limit
end</pre>
 </div>
 
 </div>

</div>

<div id="method-c-key_space_limit-3D" class="method-detail ">
 
 <div class="method-heading">
 key_space_limit=(v)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="key_space_limit-3D-source">
 <pre># File lib/rack/utils.rb, line 92
def self.key_space_limit=(v)
 self.default_query_parser = self.default_query_parser.new_space_limit(v)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-c-param_depth_limit" class="method-detail ">
 
 <div class="method-heading">
 param_depth_limit()
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="param_depth_limit-source">
 <pre># File lib/rack/utils.rb, line 80
def self.param_depth_limit
 default_query_parser.param_depth_limit
end</pre>
 </div>
 
 </div>

</div>

<div id="method-c-param_depth_limit-3D" class="method-detail ">
 
 <div class="method-heading">
 param_depth_limit=(v)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="param_depth_limit-3D-source">
 <pre># File lib/rack/utils.rb, line 84
def self.param_depth_limit=(v)
 self.default_query_parser = self.default_query_parser.new_depth_limit(v)
end</pre>
 </div>
 
 </div>

</div>

</section>
 
 <section id="public-instance-5Buntitled-5D-method-details" class="method-section">
 <header>
 <h3>Public Instance Methods</h3>
 </header>

<div id="method-i-add_cookie_to_header" class="method-detail ">
 
 <div class="method-heading">
 add_cookie_to_header(header, key, value)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="add_cookie_to_header-source">
 <pre># File lib/rack/utils.rb, line 267
def add_cookie_to_header(header, key, value)
 case value
 when Hash
 domain = &quot;; domain=#{value[:domain]}&quot; if value[:domain]
 path = &quot;; path=#{value[:path]}&quot; if value[:path]
 max_age = &quot;; max-age=#{value[:max_age]}&quot; if value[:max_age]
 expires = &quot;; expires=#{value[:expires].httpdate}&quot; if value[:expires]
 secure = &quot;; secure&quot; if value[:secure]
 httponly = &quot;; HttpOnly&quot; if (value.key?(:httponly) ? value[:httponly] : value[:http_only])
 same_site =
 case value[:same_site]
 when false, nil
 nil
 when :none, &#39;None&#39;, :None
 &#39;; SameSite=None&#39;
 when :lax, &#39;Lax&#39;, :Lax
 &#39;; SameSite=Lax&#39;
 when true, :strict, &#39;Strict&#39;, :Strict
 &#39;; SameSite=Strict&#39;
 else
 raise ArgumentError, &quot;Invalid SameSite value: #{value[:same_site].inspect}&quot;
 end
 value = value[:value]
 end
 value = [value] unless Array === value

cookie = &quot;#{escape(key)}=#{value.map { |v| escape v }.join(&#39;&amp;&#39;)}#{domain}&quot; \
 &quot;#{path}#{max_age}#{expires}#{secure}#{httponly}#{same_site}&quot;

case header
 when nil, &#39;&#39;
 cookie
 when String
 [header, cookie].join(&quot;\n&quot;)
 when Array
 (header + [cookie]).join(&quot;\n&quot;)
 else
 raise ArgumentError, &quot;Unrecognized cookie header value. Expected String, Array, or nil, got #{header.inspect}&quot;
 end
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-add_remove_cookie_to_header" class="method-detail ">
 
 <div class="method-heading">
 add_remove_cookie_to_header(header, key, value = {})
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Adds a cookie that will remove a cookie from the client. Hence the strange method name.

<div class="method-source-code" id="add_remove_cookie_to_header-source">
 <pre># File lib/rack/utils.rb, line 350
def add_remove_cookie_to_header(header, key, value = {})
 new_header = make_delete_cookie_header(header, key, value)

add_cookie_to_header(new_header, key,
 { value: &#39;&#39;, path: nil, domain: nil,
 max_age: &#39;0&#39;,
 expires: Time.at(0) }.merge(value))

end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-best_q_match" class="method-detail ">
 
 <div class="method-heading">
 best_q_match(q_value_header, available_mimes)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Return best accept value to use, based on the algorithm in RFC 2616 Section 14. If there are multiple best matches (same specificity and quality), the value returned is arbitrary.

<div class="method-source-code" id="best_q_match-source">
 <pre># File lib/rack/utils.rb, line 159
def best_q_match(q_value_header, available_mimes)
 values = q_values(q_value_header)

matches = values.map do |req_mime, quality|
 match = available_mimes.find { |am| Rack::Mime.match?(am, req_mime) }
 next unless match
 [match, quality]
 end.compact.sort_by do |match, quality|
 (match.split(&#39;/&#39;, 2).count(&#39;*&#39;) * -10) + quality
 end.last
 matches &amp;&amp; matches.first
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-build_nested_query" class="method-detail ">
 
 <div class="method-heading">
 build_nested_query(value, prefix = nil)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="build_nested_query-source">
 <pre># File lib/rack/utils.rb, line 126
def build_nested_query(value, prefix = nil)
 case value
 when Array
 value.map { |v|
 build_nested_query(v, &quot;#{prefix}[]&quot;)
 }.join(&quot;&amp;&quot;)
 when Hash
 value.map { |k, v|
 build_nested_query(v, prefix ? &quot;#{prefix}[#{escape(k)}]&quot; : escape(k))
 }.delete_if(&amp;:empty?).join(&#39;&amp;&#39;)
 when nil
 prefix
 else
 raise ArgumentError, &quot;value must be a Hash&quot; if prefix.nil?
 &quot;#{prefix}=#{escape(value)}&quot;
 end
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-build_query" class="method-detail ">
 
 <div class="method-heading">
 build_query(params)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="build_query-source">
 <pre># File lib/rack/utils.rb, line 116
def build_query(params)
 params.map { |k, v|
 if v.class == Array
 build_query(v.map { |x| [k, x] })
 else
 v.nil? ? escape(k) : &quot;#{escape(k)}=#{escape(v)}&quot;
 end
 }.join(&quot;&amp;&quot;)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-byte_ranges" class="method-detail ">
 
 <div class="method-heading">
 byte_ranges(env, size, max_ranges: 100)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 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.

<div class="method-source-code" id="byte_ranges-source">
 <pre># File lib/rack/utils.rb, line 382
def byte_ranges(env, size, max_ranges: 100)
 get_byte_ranges env[&#39;HTTP_RANGE&#39;], size, max_ranges: max_ranges
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-clean_path_info" class="method-detail ">
 
 <div class="method-heading">
 clean_path_info(path_info)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="clean_path_info-source">
 <pre># File lib/rack/utils.rb, line 640
def clean_path_info(path_info)
 parts = path_info.split PATH_SEPS

clean = []

parts.each do |part|
 next if part.empty? || part == &#39;.&#39;
 part == &#39;..&#39; ? clean.pop : clean &lt;&lt; part
 end

clean_path = clean.join(::File::SEPARATOR)
 clean_path.prepend(&quot;/&quot;) if parts.empty? || parts.first.empty?
 clean_path
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-clock_time" class="method-detail ">
 
 <div class="method-heading">
 clock_time()
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="clock_time-source">
 <pre># File lib/rack/utils.rb, line 97
def clock_time
 Process.clock_gettime(Process::CLOCK_MONOTONIC)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-delete_cookie_header-21" class="method-detail ">
 
 <div class="method-heading">
 delete_cookie_header!(header, key, value = {})
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="delete_cookie_header-21-source">
 <pre># File lib/rack/utils.rb, line 343
def delete_cookie_header!(header, key, value = {})
 header[SET_COOKIE] = add_remove_cookie_to_header(header[SET_COOKIE], key, value)
 nil
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-escape" class="method-detail ">
 
 <div class="method-heading">
 escape(s)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 URI escapes. (CGI style space to +)

<div class="method-source-code" id="escape-source">
 <pre># File lib/rack/utils.rb, line 38
def escape(s)
 URI.encode_www_form_component(s)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-escape_html" class="method-detail ">
 
 <div class="method-heading">
 escape_html(string)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Escape ampersands, brackets and quotes to their HTML/XML entities.

<div class="method-source-code" id="escape_html-source">
 <pre># File lib/rack/utils.rb, line 184
def escape_html(string)
 string.to_s.gsub(ESCAPE_HTML_PATTERN){|c| ESCAPE_HTML[c] }
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-escape_path" class="method-detail ">
 
 <div class="method-heading">
 escape_path(s)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Like URI escaping, but with %20 instead of +. Strictly speaking this is true URI escaping.

<div class="method-source-code" id="escape_path-source">
 <pre># File lib/rack/utils.rb, line 44
def escape_path(s)
 RFC2396_PARSER.escape s
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-get_byte_ranges" class="method-detail ">
 
 <div class="method-heading">
 get_byte_ranges(http_range, size, max_ranges: 100)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="get_byte_ranges-source">
 <pre># File lib/rack/utils.rb, line 386
def get_byte_ranges(http_range, size, max_ranges: 100)
 # See &lt;http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35&gt;
 return nil unless http_range &amp;&amp; http_range =~ /bytes=([^;]+)/
 byte_range = $1
 return nil if byte_range.count(&#39;,&#39;) &gt;= max_ranges
 ranges = []
 byte_range.split(/,[ \t]*/).each do |range_spec|
 return nil unless range_spec.include?(&#39;-&#39;)
 range = range_spec.split(&#39;-&#39;)
 r0, r1 = range[0], range[1]
 if r0.nil? || r0.empty?
 return nil if r1.nil?
 # suffix-byte-range-spec, represents trailing suffix of file
 r0 = size - r1.to_i
 r0 = 0 if r0 &lt; 0
 r1 = size - 1
 else
 r0 = r0.to_i
 if r1.nil?
 r1 = size - 1
 else
 r1 = r1.to_i
 return nil if r1 &lt; r0 # backwards range is syntactically invalid
 r1 = size - 1 if r1 &gt;= size
 end
 end
 ranges &lt;&lt; (r0..r1) if r0 &lt;= r1
 end

return [] if ranges.map(&amp;:size).inject(0, :+) &gt; size

ranges
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-make_delete_cookie_header" class="method-detail ">
 
 <div class="method-heading">
 make_delete_cookie_header(header, key, value)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="make_delete_cookie_header-source">
 <pre># File lib/rack/utils.rb, line 313
def make_delete_cookie_header(header, key, value)
 case header
 when nil, &#39;&#39;
 cookies = []
 when String
 cookies = header.split(&quot;\n&quot;)
 when Array
 cookies = header
 end

key = escape(key)
 domain = value[:domain]
 path = value[:path]
 regexp = if domain
 if path
 /\A#{key}=.*(?:domain=#{domain}(?:;|$).*path=#{path}(?:;|$)|path=#{path}(?:;|$).*domain=#{domain}(?:;|$))/
 else
 /\A#{key}=.*domain=#{domain}(?:;|$)/
 end
 elsif path
 /\A#{key}=.*path=#{path}(?:;|$)/
 else
 /\A#{key}=/
 end

cookies.reject! { |cookie| regexp.match? cookie }

cookies.join(&quot;\n&quot;)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-parse_cookies" class="method-detail ">
 
 <div class="method-heading">
 parse_cookies(env)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="parse_cookies-source">
 <pre># File lib/rack/utils.rb, line 250
def parse_cookies(env)
 parse_cookies_header env[HTTP_COOKIE]
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-parse_cookies_header" class="method-detail ">
 
 <div class="method-heading">
 parse_cookies_header(header)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="parse_cookies_header-source">
 <pre># File lib/rack/utils.rb, line 254
def parse_cookies_header(header)
 # According to RFC 6265:
 # The syntax for cookie headers only supports semicolons
 # User Agent -&gt; Server ==
 # Cookie: SID=31d4d96e407aad42; lang=en-US
 return {} unless header
 header.split(/[;] */n).each_with_object({}) do |cookie, cookies|
 next if cookie.empty?
 key, value = cookie.split(&#39;=&#39;, 2)
 cookies[key] = (unescape(value) rescue value) unless cookies.key?(key)
 end
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-parse_nested_query" class="method-detail ">
 
 <div class="method-heading">
 parse_nested_query(qs, d = nil)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="parse_nested_query-source">
 <pre># File lib/rack/utils.rb, line 112
def parse_nested_query(qs, d = nil)
 Rack::Utils.default_query_parser.parse_nested_query(qs, d)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-parse_query" class="method-detail ">
 
 <div class="method-heading">
 parse_query(qs, d = nil, &amp;unescaper)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="parse_query-source">
 <pre># File lib/rack/utils.rb, line 108
def parse_query(qs, d = nil, &amp;unescaper)
 Rack::Utils.default_query_parser.parse_query(qs, d, &amp;unescaper)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-q_values" class="method-detail ">
 
 <div class="method-heading">
 q_values(q_value_header)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="q_values-source">
 <pre># File lib/rack/utils.rb, line 144
def q_values(q_value_header)
 q_value_header.to_s.split(&#39;,&#39;).map do |part|
 value, parameters = part.split(&#39;;&#39;, 2).map(&amp;:strip)
 quality = 1.0
 if parameters &amp;&amp; (md = /\Aq=([\d.]+)/.match(parameters))
 quality = md[1].to_f
 end
 [value, quality]
 end
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-rfc2109" class="method-detail ">
 
 <div class="method-heading">
 rfc2109(time)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Modified version of stdlib time.rb Time#rfc2822 to use &#39;%d-%b-%Y&#39; instead of &#39;% %b %Y&#39;. It assumes that the time is in GMT to comply to the RFC 2109.

NOTE: I&#39;m not sure the RFC says it requires GMT, but is ambiguous enough that I&#39;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.

<div class="method-source-code" id="rfc2109-source">
 <pre># File lib/rack/utils.rb, line 373
def rfc2109(time)
 wday = RFC2822_DAY_NAME[time.wday]
 mon = RFC2822_MONTH_NAME[time.mon - 1]
 time.strftime(&quot;#{wday}, %d-#{mon}-%Y %H:%M:%S GMT&quot;)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-rfc2822" class="method-detail ">
 
 <div class="method-heading">
 rfc2822(time)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="rfc2822-source">
 <pre># File lib/rack/utils.rb, line 360
def rfc2822(time)
 time.rfc2822
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-secure_compare" class="method-detail ">
 
 <div class="method-heading">
 secure_compare(a, b)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Constant time string comparison.

NOTE: the values compared should be of fixed length, such as strings that have already been processed by HMAC. This should not be used on variable length plaintext strings because it could leak length info via timing attacks.

<div class="method-source-code" id="secure_compare-source">
 <pre># File lib/rack/utils.rb, line 426
def secure_compare(a, b)
 return false unless a.bytesize == b.bytesize

l = a.unpack(&quot;C*&quot;)

r, i = 0, -1
 b.each_byte { |v| r |= v ^ l[i += 1] }
 r == 0
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-select_best_encoding" class="method-detail ">
 
 <div class="method-heading">
 select_best_encoding(available_encodings, accept_encoding)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Given an array of available encoding strings, and an array of acceptable encodings for a request, where each element of the acceptable encodings array is an array where the first element is an encoding name and the second element is the numeric priority for the encoding, return the available encoding with the highest priority.

The accept_encoding argument is typically generated by calling <a href="Request/Helpers.html#method-i-accept_encoding"><code>Request#accept_encoding</code></a>.

Example:

<pre class="ruby">select_best_encoding(%w(compress gzip identity),
 [[&quot;compress&quot;, 0.5], [&quot;gzip&quot;, 1.0]])
# =&gt; &quot;gzip&quot;
</pre>

To reduce denial of service potential, only the first 16 acceptable encodings are considered.

<div class="method-source-code" id="select_best_encoding-source">
 <pre># File lib/rack/utils.rb, line 206
def select_best_encoding(available_encodings, accept_encoding)
 # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

# Only process the first 16 encodings
 accept_encoding = accept_encoding[0...16]
 expanded_accept_encoding = []
 wildcard_seen = false

accept_encoding.each do |m, q|
 preference = available_encodings.index(m) || available_encodings.size

if m == &quot;*&quot;
 unless wildcard_seen
 (available_encodings - accept_encoding.map(&amp;:first)).each do |m2|
 expanded_accept_encoding &lt;&lt; [m2, q, preference]
 end
 wildcard_seen = true
 end
 else
 expanded_accept_encoding &lt;&lt; [m, q, preference]
 end
 end

encoding_candidates = expanded_accept_encoding
 .sort do |(_, q1, p1), (_, q2, p2)|
 if r = (q1 &lt;=&gt; q2).nonzero?
 -r
 else
 (p1 &lt;=&gt; p2).nonzero? || 0
 end
 end
 .map!(&amp;:first)

unless encoding_candidates.include?(&quot;identity&quot;)
 encoding_candidates.push(&quot;identity&quot;)
 end

expanded_accept_encoding.each do |m, q|
 encoding_candidates.delete(m) if q == 0.0
 end

(encoding_candidates &amp; available_encodings)[0]
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-set_cookie_header-21" class="method-detail ">
 
 <div class="method-heading">
 set_cookie_header!(header, key, value)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="set_cookie_header-21-source">
 <pre># File lib/rack/utils.rb, line 308
def set_cookie_header!(header, key, value)
 header[SET_COOKIE] = add_cookie_to_header(header[SET_COOKIE], key, value)
 nil
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-status_code" class="method-detail ">
 
 <div class="method-heading">
 status_code(status)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="status_code-source">
 <pre># File lib/rack/utils.rb, line 630
def status_code(status)
 if status.is_a?(Symbol)
 SYMBOL_TO_STATUS_CODE.fetch(status) { raise ArgumentError, &quot;Unrecognized status code #{status.inspect}&quot; }
 else
 status.to_i
 end
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-unescape" class="method-detail ">
 
 <div class="method-heading">
 unescape(s, encoding = Encoding::UTF_8)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Unescapes a URI escaped string with <code>encoding</code>. <code>encoding</code> will be the target encoding of the string returned, and it defaults to UTF-8

<div class="method-source-code" id="unescape-source">
 <pre># File lib/rack/utils.rb, line 56
def unescape(s, encoding = Encoding::UTF_8)
 URI.decode_www_form_component(s, encoding)
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-unescape_path" class="method-detail ">
 
 <div class="method-heading">
 unescape_path(s)
 
 click to toggle source
 
 </div>

<div class="method-description">
 
 Unescapes the *path* component of a URI. See <a href="Utils.html#method-i-unescape"><code>Rack::Utils.unescape</code></a> for unescaping query parameters or form components.

<div class="method-source-code" id="unescape_path-source">
 <pre># File lib/rack/utils.rb, line 50
def unescape_path(s)
 RFC2396_PARSER.unescape s
end</pre>
 </div>
 
 </div>

</div>

<div id="method-i-valid_path-3F" class="method-detail ">
 
 <div class="method-heading">
 valid_path?(path)
 
 click to toggle source
 
 </div>

<div class="method-source-code" id="valid_path-3F-source">
 <pre># File lib/rack/utils.rb, line 657
def valid_path?(path)
 path.valid_encoding? &amp;&amp; !path.include?(NULL_BYTE)
end</pre>
 </div>
 
 </div>

</div>

</section>
 
 </section>

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