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234 lines
8.5 KiB
Ruby
234 lines
8.5 KiB
Ruby
require 'active_support/core_ext/hash/keys'
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require 'active_support/core_ext/object/blank'
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module ActionDispatch
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module Session
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# This cookie-based session store is the Rails default. Sessions typically
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# contain at most a user_id and flash message; both fit within the 4K cookie
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# size limit. Cookie-based sessions are dramatically faster than the
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# alternatives.
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#
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# If you have more than 4K of session data or don't want your data to be
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# visible to the user, pick another session store.
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#
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# CookieOverflow is raised if you attempt to store more than 4K of data.
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#
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# A message digest is included with the cookie to ensure data integrity:
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# a user cannot alter his +user_id+ without knowing the secret key
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# included in the hash. New apps are generated with a pregenerated secret
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# in config/environment.rb. Set your own for old apps you're upgrading.
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#
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# Session options:
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#
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# * <tt>:secret</tt>: An application-wide key string or block returning a
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# string called per generated digest. The block is called with the
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# CGI::Session instance as an argument. It's important that the secret
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# is not vulnerable to a dictionary attack. Therefore, you should choose
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# a secret consisting of random numbers and letters and more than 30
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# characters. Examples:
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#
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# :secret => '449fe2e7daee471bffae2fd8dc02313d'
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# :secret => Proc.new { User.current_user.secret_key }
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#
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# * <tt>:digest</tt>: The message digest algorithm used to verify session
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# integrity defaults to 'SHA1' but may be any digest provided by OpenSSL,
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# such as 'MD5', 'RIPEMD160', 'SHA256', etc.
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#
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# To generate a secret key for an existing application, run
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# "rake secret" and set the key in config/environment.rb.
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#
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# Note that changing digest or secret invalidates all existing sessions!
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class CookieStore
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# Cookies can typically store 4096 bytes.
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MAX = 4096
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SECRET_MIN_LENGTH = 30 # characters
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DEFAULT_OPTIONS = {
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:key => '_session_id',
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:domain => nil,
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:path => "/",
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:expire_after => nil,
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:httponly => true
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}.freeze
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class OptionsHash < Hash
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def initialize(by, env, default_options)
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@session_data = env[CookieStore::ENV_SESSION_KEY]
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default_options.each { |key, value| self[key] = value }
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end
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def [](key)
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key == :id ? @session_data[:session_id] : super(key)
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end
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end
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ENV_SESSION_KEY = "rack.session".freeze
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ENV_SESSION_OPTIONS_KEY = "rack.session.options".freeze
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HTTP_SET_COOKIE = "Set-Cookie".freeze
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# Raised when storing more than 4K of session data.
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class CookieOverflow < StandardError; end
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def initialize(app, options = {})
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# Process legacy CGI options
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options = options.symbolize_keys
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if options.has_key?(:session_path)
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options[:path] = options.delete(:session_path)
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end
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if options.has_key?(:session_key)
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options[:key] = options.delete(:session_key)
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end
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if options.has_key?(:session_http_only)
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options[:httponly] = options.delete(:session_http_only)
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end
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@app = app
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# The session_key option is required.
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ensure_session_key(options[:key])
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@key = options.delete(:key).freeze
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# The secret option is required.
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ensure_secret_secure(options[:secret])
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@secret = options.delete(:secret).freeze
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@digest = options.delete(:digest) || 'SHA1'
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@verifier = verifier_for(@secret, @digest)
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@default_options = DEFAULT_OPTIONS.merge(options).freeze
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freeze
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end
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def call(env)
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env[ENV_SESSION_KEY] = AbstractStore::SessionHash.new(self, env)
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env[ENV_SESSION_OPTIONS_KEY] = OptionsHash.new(self, env, @default_options)
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status, headers, body = @app.call(env)
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session_data = env[ENV_SESSION_KEY]
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options = env[ENV_SESSION_OPTIONS_KEY]
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if !session_data.is_a?(AbstractStore::SessionHash) || session_data.send(:loaded?) || options[:expire_after]
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session_data.send(:load!) if session_data.is_a?(AbstractStore::SessionHash) && !session_data.send(:loaded?)
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session_data = marshal(session_data.to_hash)
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raise CookieOverflow if session_data.size > MAX
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cookie = Hash.new
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cookie[:value] = session_data
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unless options[:expire_after].nil?
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cookie[:expires] = Time.now + options[:expire_after]
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end
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cookie = build_cookie(@key, cookie.merge(options))
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unless headers[HTTP_SET_COOKIE].blank?
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headers[HTTP_SET_COOKIE] << "\n#{cookie}"
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else
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headers[HTTP_SET_COOKIE] = cookie
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end
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end
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[status, headers, body]
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end
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private
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# Should be in Rack::Utils soon
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def build_cookie(key, value)
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case value
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when Hash
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domain = "; domain=" + value[:domain] if value[:domain]
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path = "; path=" + value[:path] if value[:path]
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# According to RFC 2109, we need dashes here.
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# N.B.: cgi.rb uses spaces...
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expires = "; expires=" + value[:expires].clone.gmtime.
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strftime("%a, %d-%b-%Y %H:%M:%S GMT") if value[:expires]
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secure = "; secure" if value[:secure]
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httponly = "; HttpOnly" if value[:httponly]
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value = value[:value]
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end
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value = [value] unless Array === value
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cookie = Rack::Utils.escape(key) + "=" +
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value.map { |v| Rack::Utils.escape(v) }.join("&") +
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"#{domain}#{path}#{expires}#{secure}#{httponly}"
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end
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def load_session(env)
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request = Rack::Request.new(env)
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session_data = request.cookies[@key]
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data = unmarshal(session_data) || persistent_session_id!({})
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data.stringify_keys!
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[data["session_id"], data]
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end
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# Marshal a session hash into safe cookie data. Include an integrity hash.
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def marshal(session)
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@verifier.generate(persistent_session_id!(session))
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end
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# Unmarshal cookie data to a hash and verify its integrity.
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def unmarshal(cookie)
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persistent_session_id!(@verifier.verify(cookie)) if cookie
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rescue ActiveSupport::MessageVerifier::InvalidSignature
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nil
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end
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def ensure_session_key(key)
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if key.blank?
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raise ArgumentError, 'A key is required to write a ' +
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'cookie containing the session data. Use ' +
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'config.session_store :cookie_store, { :key => ' +
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'"_myapp_session" } in config/application.rb'
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end
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end
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# To prevent users from using something insecure like "Password" we make sure that the
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# secret they've provided is at least 30 characters in length.
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def ensure_secret_secure(secret)
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# There's no way we can do this check if they've provided a proc for the
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# secret.
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return true if secret.is_a?(Proc)
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if secret.blank?
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raise ArgumentError, "A secret is required to generate an " +
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"integrity hash for cookie session data. Use " +
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"config.secret_token = \"some secret phrase of at " +
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"least #{SECRET_MIN_LENGTH} characters\"" +
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"in config/application.rb"
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end
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if secret.length < SECRET_MIN_LENGTH
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raise ArgumentError, "Secret should be something secure, " +
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"like \"#{ActiveSupport::SecureRandom.hex(16)}\". The value you " +
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"provided, \"#{secret}\", is shorter than the minimum length " +
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"of #{SECRET_MIN_LENGTH} characters"
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end
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end
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def verifier_for(secret, digest)
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key = secret.respond_to?(:call) ? secret.call : secret
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ActiveSupport::MessageVerifier.new(key, digest)
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end
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def generate_sid
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ActiveSupport::SecureRandom.hex(16)
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end
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def persistent_session_id!(data)
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(data ||= {}).merge!(inject_persistent_session_id(data))
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end
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def inject_persistent_session_id(data)
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requires_session_id?(data) ? { "session_id" => generate_sid } : {}
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end
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def requires_session_id?(data)
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if data
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data.respond_to?(:key?) && !data.key?("session_id")
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else
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true
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end
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end
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end
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end
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end
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