module ActionDispatch module Http # Provides access to the request's HTTP headers from the environment. # # env = { "CONTENT_TYPE" => "text/plain", "HTTP_USER_AGENT" => "curl/7.43.0" } # headers = ActionDispatch::Http::Headers.new(env) # headers["Content-Type"] # => "text/plain" # headers["User-Agent"] # => "curl/7/43/0" # # Also note that when headers are mapped to CGI-like variables by the Rack # server, both dashes and underscores are converted to underscores. This # ambiguity cannot be resolved at this stage anymore. Both underscores and # dashes have to be interpreted as if they were originally sent as dashes. # # # GET / HTTP/1.1 # # ... # # User-Agent: curl/7.43.0 # # X_Custom_Header: token # # headers["X_Custom_Header"] # => nil # headers["X-Custom-Header"] # => "token" class Headers CGI_VARIABLES = Set.new(%W[ AUTH_TYPE CONTENT_LENGTH CONTENT_TYPE GATEWAY_INTERFACE HTTPS PATH_INFO PATH_TRANSLATED QUERY_STRING REMOTE_ADDR REMOTE_HOST REMOTE_IDENT REMOTE_USER REQUEST_METHOD SCRIPT_NAME SERVER_NAME SERVER_PORT SERVER_PROTOCOL SERVER_SOFTWARE ]).freeze HTTP_HEADER = /\A[A-Za-z0-9-]+\z/ include Enumerable def self.from_hash(hash) new ActionDispatch::Request.new hash end def initialize(request) # :nodoc: @req = request end # Returns the value for the given key mapped to @env. def [](key) @req.get_header env_name(key) end # Sets the given value for the key mapped to @env. def []=(key, value) @req.set_header env_name(key), value end # Add a value to a multivalued header like Vary or Accept-Encoding. def add(key, value) @req.add_header env_name(key), value end def key?(key) @req.has_header? env_name(key) end alias :include? :key? DEFAULT = Object.new # :nodoc: # Returns the value for the given key mapped to @env. # # If the key is not found and an optional code block is not provided, # raises a KeyError exception. # # If the code block is provided, then it will be run and # its result returned. def fetch(key, default = DEFAULT) @req.fetch_header(env_name(key)) do return default unless default == DEFAULT return yield if block_given? raise NameError, key end end def each(&block) @req.each_header(&block) end # Returns a new Http::Headers instance containing the contents of # headers_or_env and the original instance. def merge(headers_or_env) headers = @req.dup.headers headers.merge!(headers_or_env) headers end # Adds the contents of headers_or_env to original instance # entries; duplicate keys are overwritten with the values from # headers_or_env. def merge!(headers_or_env) headers_or_env.each do |key, value| @req.set_header env_name(key), value end end def env; @req.env.dup; end private # Converts an HTTP header name to an environment variable name if it is # not contained within the headers hash. def env_name(key) key = key.to_s if key =~ HTTP_HEADER key = key.upcase.tr('-', '_') key = "HTTP_" + key unless CGI_VARIABLES.include?(key) end key end end end end