Class: Rack::Lint

Inherits:
Object
  • Object
show all
Includes:
Assertion
Defined in:
lib/rack/lint.rb

Overview

Rack::Lint validates your application and the requests and responses according to the Rack spec.

Defined Under Namespace

Modules: Assertion Classes: ErrorWrapper, HijackWrapper, InputWrapper, LintError

Instance Method Summary (collapse)

Methods included from Assertion

#assert

Constructor Details

- (Lint) initialize(app)

Returns a new instance of Lint



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# File 'lib/rack/lint.rb', line 9

def initialize(app)
  @app = app
  @content_length = nil
end

Instance Method Details

- (Object) _call(env)



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# File 'lib/rack/lint.rb', line 40

def _call(env)
  ## It takes exactly one argument, the *environment*
  assert("No env given") { env }
  check_env env

  env['rack.input'] = InputWrapper.new(env['rack.input'])
  env['rack.errors'] = ErrorWrapper.new(env['rack.errors'])

  ## and returns an Array of exactly three values:
  status, headers, @body = @app.call(env)
  ## The *status*,
  check_status status
  ## the *headers*,
  check_headers headers

  check_hijack_response headers, env

  ## and the *body*.
  check_content_type status, headers
  check_content_length status, headers
  @head_request = env["REQUEST_METHOD"] == "HEAD"
  [status, headers, self]
end

- (Object) call(env = nil)

A Rack application is a Ruby object (not a class) that responds to call.



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# File 'lib/rack/lint.rb', line 36

def call(env=nil)
  dup._call(env)
end

- (Object) check_content_length(status, headers)

The Content-Length



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# File 'lib/rack/lint.rb', line 612

def check_content_length(status, headers)
  headers.each { |key, value|
    if key.downcase == 'content-length'
      ## There must not be a <tt>Content-Length</tt> header when the
      ## +Status+ is 1xx, 204, 205 or 304.
      assert("Content-Length header found in #{status} response, not allowed") {
        not Rack::Utils::STATUS_WITH_NO_ENTITY_BODY.include? status.to_i
      }
      @content_length = value
    end
  }
end

- (Object) check_content_type(status, headers)

The Content-Type



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# File 'lib/rack/lint.rb', line 598

def check_content_type(status, headers)
  headers.each { |key, value|
    ## There must not be a <tt>Content-Type</tt>, when the +Status+ is 1xx,
    ## 204, 205 or 304.
    if key.downcase == "content-type"
      assert("Content-Type header found in #{status} response, not allowed") {
        not Rack::Utils::STATUS_WITH_NO_ENTITY_BODY.include? status.to_i
      }
      return
    end
  }
end

- (Object) check_env(env)

The Environment



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# File 'lib/rack/lint.rb', line 65

def check_env(env)
  ## The environment must be an instance of Hash that includes
  ## CGI-like headers.  The application is free to modify the
  ## environment.
  assert("env #{env.inspect} is not a Hash, but #{env.class}") {
    env.kind_of? Hash
  }

  ##
  ## The environment is required to include these variables
  ## (adopted from PEP333), except when they'd be empty, but see
  ## below.

  ## <tt>REQUEST_METHOD</tt>:: The HTTP request method, such as
  ##                           "GET" or "POST". This cannot ever
  ##                           be an empty string, and so is
  ##                           always required.

  ## <tt>SCRIPT_NAME</tt>:: The initial portion of the request
  ##                        URL's "path" that corresponds to the
  ##                        application object, so that the
  ##                        application knows its virtual
  ##                        "location". This may be an empty
  ##                        string, if the application corresponds
  ##                        to the "root" of the server.

  ## <tt>PATH_INFO</tt>:: The remainder of the request URL's
  ##                      "path", designating the virtual
  ##                      "location" of the request's target
  ##                      within the application. This may be an
  ##                      empty string, if the request URL targets
  ##                      the application root and does not have a
  ##                      trailing slash. This value may be
  ##                      percent-encoded when I originating from
  ##                      a URL.

  ## <tt>QUERY_STRING</tt>:: The portion of the request URL that
  ##                         follows the <tt>?</tt>, if any. May be
  ##                         empty, but is always required!

  ## <tt>SERVER_NAME</tt>, <tt>SERVER_PORT</tt>:: When combined with <tt>SCRIPT_NAME</tt> and <tt>PATH_INFO</tt>, these variables can be used to complete the URL. Note, however, that <tt>HTTP_HOST</tt>, if present, should be used in preference to <tt>SERVER_NAME</tt> for reconstructing the request URL.  <tt>SERVER_NAME</tt> and <tt>SERVER_PORT</tt> can never be empty strings, and so are always required.

  ## <tt>HTTP_</tt> Variables:: Variables corresponding to the
  ##                            client-supplied HTTP request
  ##                            headers (i.e., variables whose
  ##                            names begin with <tt>HTTP_</tt>). The
  ##                            presence or absence of these
  ##                            variables should correspond with
  ##                            the presence or absence of the
  ##                            appropriate HTTP header in the
  ##                            request. See <a href="https://tools.ietf.org/html/rfc3875#section-4.1.18">
  ##                            RFC3875 section 4.1.18</a> for specific behavior.

  ## In addition to this, the Rack environment must include these
  ## Rack-specific variables:

  ## <tt>rack.version</tt>:: The Array representing this version of Rack. See Rack::VERSION, that corresponds to the version of this SPEC.
  ## <tt>rack.url_scheme</tt>:: +http+ or +https+, depending on the request URL.
  ## <tt>rack.input</tt>:: See below, the input stream.
  ## <tt>rack.errors</tt>:: See below, the error stream.
  ## <tt>rack.multithread</tt>:: true if the application object may be simultaneously invoked by another thread in the same process, false otherwise.
  ## <tt>rack.multiprocess</tt>:: true if an equivalent application object may be simultaneously invoked by another process, false otherwise.
  ## <tt>rack.run_once</tt>:: true if the server expects (but does not guarantee!) that the application will only be invoked this one time during the life of its containing process. Normally, this will only be true for a server based on CGI (or something similar).
  ## <tt>rack.hijack?</tt>:: present and true if the server supports connection hijacking. See below, hijacking.
  ## <tt>rack.hijack</tt>:: an object responding to #call that must be called at least once before using rack.hijack_io. It is recommended #call return rack.hijack_io as well as setting it in env if necessary.
  ## <tt>rack.hijack_io</tt>:: if rack.hijack? is true, and rack.hijack has received #call, this will contain an object resembling an IO. See hijacking.
  ##

  ## Additional environment specifications have approved to
  ## standardized middleware APIs.  None of these are required to
  ## be implemented by the server.

  ## <tt>rack.session</tt>:: A hash like interface for storing request session data.
  ##                         The store must implement:
  if session = env['rack.session']
    ##                         store(key, value)         (aliased as []=);
    assert("session #{session.inspect} must respond to store and []=") {
      session.respond_to?(:store) && session.respond_to?(:[]=)
    }

    ##                         fetch(key, default = nil) (aliased as []);
    assert("session #{session.inspect} must respond to fetch and []") {
      session.respond_to?(:fetch) && session.respond_to?(:[])
    }

    ##                         delete(key);
    assert("session #{session.inspect} must respond to delete") {
      session.respond_to?(:delete)
    }

    ##                         clear;
    assert("session #{session.inspect} must respond to clear") {
      session.respond_to?(:clear)
    }
  end

  ## <tt>rack.logger</tt>:: A common object interface for logging messages.
  ##                        The object must implement:
  if logger = env['rack.logger']
    ##                         info(message, &block)
    assert("logger #{logger.inspect} must respond to info") {
      logger.respond_to?(:info)
    }

    ##                         debug(message, &block)
    assert("logger #{logger.inspect} must respond to debug") {
      logger.respond_to?(:debug)
    }

    ##                         warn(message, &block)
    assert("logger #{logger.inspect} must respond to warn") {
      logger.respond_to?(:warn)
    }

    ##                         error(message, &block)
    assert("logger #{logger.inspect} must respond to error") {
      logger.respond_to?(:error)
    }

    ##                         fatal(message, &block)
    assert("logger #{logger.inspect} must respond to fatal") {
      logger.respond_to?(:fatal)
    }
  end

  ## The server or the application can store their own data in the
  ## environment, too.  The keys must contain at least one dot,
  ## and should be prefixed uniquely.  The prefix <tt>rack.</tt>
  ## is reserved for use with the Rack core distribution and other
  ## accepted specifications and must not be used otherwise.
  ##

  %w[REQUEST_METHOD SERVER_NAME SERVER_PORT
     QUERY_STRING
     rack.version rack.input rack.errors
     rack.multithread rack.multiprocess rack.run_once].each { |header|
    assert("env missing required key #{header}") { env.include? header }
  }

  ## The environment must not contain the keys
  ## <tt>HTTP_CONTENT_TYPE</tt> or <tt>HTTP_CONTENT_LENGTH</tt>
  ## (use the versions without <tt>HTTP_</tt>).
  %w[HTTP_CONTENT_TYPE HTTP_CONTENT_LENGTH].each { |header|
    assert("env contains #{header}, must use #{header[5,-1]}") {
      not env.include? header
    }
  }

  ## The CGI keys (named without a period) must have String values.
  env.each { |key, value|
    next  if key.include? "."   # Skip extensions
    assert("env variable #{key} has non-string value #{value.inspect}") {
      value.kind_of? String
    }
  }

  ##
  ## There are the following restrictions:

  ## * <tt>rack.version</tt> must be an array of Integers.
  assert("rack.version must be an Array, was #{env["rack.version"].class}") {
    env["rack.version"].kind_of? Array
  }
  ## * <tt>rack.url_scheme</tt> must either be +http+ or +https+.
  assert("rack.url_scheme unknown: #{env["rack.url_scheme"].inspect}") {
    %w[http https].include? env["rack.url_scheme"]
  }

  ## * There must be a valid input stream in <tt>rack.input</tt>.
  check_input env["rack.input"]
  ## * There must be a valid error stream in <tt>rack.errors</tt>.
  check_error env["rack.errors"]
  ## * There may be a valid hijack stream in <tt>rack.hijack_io</tt>
  check_hijack env

  ## * The <tt>REQUEST_METHOD</tt> must be a valid token.
  assert("REQUEST_METHOD unknown: #{env["REQUEST_METHOD"]}") {
    env["REQUEST_METHOD"] =~ /\A[0-9A-Za-z!\#$%&'*+.^_`|~-]+\z/
  }

  ## * The <tt>SCRIPT_NAME</tt>, if non-empty, must start with <tt>/</tt>
  assert("SCRIPT_NAME must start with /") {
    !env.include?("SCRIPT_NAME") ||
    env["SCRIPT_NAME"] == "" ||
    env["SCRIPT_NAME"] =~ /\A\//
  }
  ## * The <tt>PATH_INFO</tt>, if non-empty, must start with <tt>/</tt>
  assert("PATH_INFO must start with /") {
    !env.include?("PATH_INFO") ||
    env["PATH_INFO"] == "" ||
    env["PATH_INFO"] =~ /\A\//
  }
  ## * The <tt>CONTENT_LENGTH</tt>, if given, must consist of digits only.
  assert("Invalid CONTENT_LENGTH: #{env["CONTENT_LENGTH"]}") {
    !env.include?("CONTENT_LENGTH") || env["CONTENT_LENGTH"] =~ /\A\d+\z/
  }

  ## * One of <tt>SCRIPT_NAME</tt> or <tt>PATH_INFO</tt> must be
  ##   set.  <tt>PATH_INFO</tt> should be <tt>/</tt> if
  ##   <tt>SCRIPT_NAME</tt> is empty.
  assert("One of SCRIPT_NAME or PATH_INFO must be set (make PATH_INFO '/' if SCRIPT_NAME is empty)") {
    env["SCRIPT_NAME"] || env["PATH_INFO"]
  }
  ##   <tt>SCRIPT_NAME</tt> never should be <tt>/</tt>, but instead be empty.
  assert("SCRIPT_NAME cannot be '/', make it '' and PATH_INFO '/'") {
    env["SCRIPT_NAME"] != "/"
  }
end

- (Object) check_error(error)

The Error Stream



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# File 'lib/rack/lint.rb', line 390

def check_error(error)
  ## The error stream must respond to +puts+, +write+ and +flush+.
  [:puts, :write, :flush].each { |method|
    assert("rack.error #{error} does not respond to ##{method}") {
      error.respond_to? method
    }
  }
end

- (Object) check_headers(header)

The Headers



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# File 'lib/rack/lint.rb', line 559

def check_headers(header)
  ## The header must respond to +each+, and yield values of key and value.
  assert("headers object should respond to #each, but doesn't (got #{header.class} as headers)") {
     header.respond_to? :each
  }
  header.each { |key, value|
    ## Special headers starting "rack." are for communicating with the
    ## server, and must not be sent back to the client.
    next if key =~ /^rack\..+$/

    ## The header keys must be Strings.
    assert("header key must be a string, was #{key.class}") {
      key.kind_of? String
    }
    ## The header must not contain a +Status+ key,
    assert("header must not contain Status") { key.downcase != "status" }
    ## contain keys with <tt>:</tt> or newlines in their name,
    assert("header names must not contain : or \\n") { key !~ /[:\n]/ }
    ## contain keys names that end in <tt>-</tt> or <tt>_</tt>,
    assert("header names must not end in - or _") { key !~ /[-_]\z/ }
    ## but only contain keys that consist of
    ## letters, digits, <tt>_</tt> or <tt>-</tt> and start with a letter.
    assert("invalid header name: #{key}") { key =~ /\A[a-zA-Z][a-zA-Z0-9_-]*\z/ }

    ## The values of the header must be Strings,
    assert("a header value must be a String, but the value of " +
      "'#{key}' is a #{value.class}") { value.kind_of? String }
    ## consisting of lines (for multiple header values, e.g. multiple
    ## <tt>Set-Cookie</tt> values) separated by "\\n".
    value.split("\n").each { |item|
      ## The lines must not contain characters below 037.
      assert("invalid header value #{key}: #{item.inspect}") {
        item !~ /[\000-\037]/
      }
    }
  }
end

- (Object) check_hijack(env)

Hijacking

AUTHORS: n.b. The trailing whitespace between paragraphs is important and should not be removed. The whitespace creates paragraphs in the RDoc output.

Request (before status)



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# File 'lib/rack/lint.rb', line 455

def check_hijack(env)
  if env['rack.hijack?']
    ## If rack.hijack? is true then rack.hijack must respond to #call.
    original_hijack = env['rack.hijack']
    assert("rack.hijack must respond to call") { original_hijack.respond_to?(:call) }
    env['rack.hijack'] = proc do
      ## rack.hijack must return the io that will also be assigned (or is
      ## already present, in rack.hijack_io.
      io = original_hijack.call
      HijackWrapper.new(io)
      ## 
      ## rack.hijack_io must respond to:
      ## <tt>read, write, read_nonblock, write_nonblock, flush, close,
      ## close_read, close_write, closed?</tt>
      ## 
      ## The semantics of these IO methods must be a best effort match to
      ## those of a normal ruby IO or Socket object, using standard
      ## arguments and raising standard exceptions. Servers are encouraged
      ## to simply pass on real IO objects, although it is recognized that
      ## this approach is not directly compatible with SPDY and HTTP 2.0.
      ## 
      ## IO provided in rack.hijack_io should preference the
      ## IO::WaitReadable and IO::WaitWritable APIs wherever supported.
      ## 
      ## There is a deliberate lack of full specification around
      ## rack.hijack_io, as semantics will change from server to server.
      ## Users are encouraged to utilize this API with a knowledge of their
      ## server choice, and servers may extend the functionality of
      ## hijack_io to provide additional features to users. The purpose of
      ## rack.hijack is for Rack to "get out of the way", as such, Rack only
      ## provides the minimum of specification and support.
      env['rack.hijack_io'] = HijackWrapper.new(env['rack.hijack_io'])
      io
    end
  else
    ## 
    ## If rack.hijack? is false, then rack.hijack should not be set.
    assert("rack.hijack? is false, but rack.hijack is present") { env['rack.hijack'].nil? }
    ## 
    ## If rack.hijack? is false, then rack.hijack_io should not be set.
    assert("rack.hijack? is false, but rack.hijack_io is present") { env['rack.hijack_io'].nil? }
  end
end

- (Object) check_hijack_response(headers, env)

Response (after headers)

It is also possible to hijack a response after the status and headers have been sent.



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# File 'lib/rack/lint.rb', line 502

def check_hijack_response(headers, env)

  # this check uses headers like a hash, but the spec only requires
  # headers respond to #each
  headers = Rack::Utils::HeaderHash.new(headers)

  ## In order to do this, an application may set the special header
  ## <tt>rack.hijack</tt> to an object that responds to <tt>call</tt>
  ## accepting an argument that conforms to the <tt>rack.hijack_io</tt>
  ## protocol.
  ## 
  ## After the headers have been sent, and this hijack callback has been
  ## called, the application is now responsible for the remaining lifecycle
  ## of the IO. The application is also responsible for maintaining HTTP
  ## semantics. Of specific note, in almost all cases in the current SPEC,
  ## applications will have wanted to specify the header Connection:close in
  ## HTTP/1.1, and not Connection:keep-alive, as there is no protocol for
  ## returning hijacked sockets to the web server. For that purpose, use the
  ## body streaming API instead (progressively yielding strings via each).
  ## 
  ## Servers must ignore the <tt>body</tt> part of the response tuple when
  ## the <tt>rack.hijack</tt> response API is in use.

  if env['rack.hijack?'] && headers['rack.hijack']
    assert('rack.hijack header must respond to #call') {
      headers['rack.hijack'].respond_to? :call
    }
    original_hijack = headers['rack.hijack']
    headers['rack.hijack'] = proc do |io|
      original_hijack.call HijackWrapper.new(io)
    end
  else
    ## 
    ## The special response header <tt>rack.hijack</tt> must only be set
    ## if the request env has <tt>rack.hijack?</tt> <tt>true</tt>.
    assert('rack.hijack header must not be present if server does not support hijacking') {
      headers['rack.hijack'].nil?
    }
  end
end

- (Object) check_input(input)

The Input Stream

The input stream is an IO-like object which contains the raw HTTP POST data.



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# File 'lib/rack/lint.rb', line 278

def check_input(input)
  ## When applicable, its external encoding must be "ASCII-8BIT" and it
  ## must be opened in binary mode, for Ruby 1.9 compatibility.
  assert("rack.input #{input} does not have ASCII-8BIT as its external encoding") {
    input.external_encoding.name == "ASCII-8BIT"
  } if input.respond_to?(:external_encoding)
  assert("rack.input #{input} is not opened in binary mode") {
    input.binmode?
  } if input.respond_to?(:binmode?)

  ## The input stream must respond to +gets+, +each+, +read+ and +rewind+.
  [:gets, :each, :read, :rewind].each { |method|
    assert("rack.input #{input} does not respond to ##{method}") {
      input.respond_to? method
    }
  }
end

- (Object) check_status(status)

The Status



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# File 'lib/rack/lint.rb', line 552

def check_status(status)
  ## This is an HTTP status. When parsed as integer (+to_i+), it must be
  ## greater than or equal to 100.
  assert("Status must be >=100 seen as integer") { status.to_i >= 100 }
end

- (Object) close



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# File 'lib/rack/lint.rb', line 685

def close
  @closed = true
  @body.close  if @body.respond_to?(:close)
end

- (Object) each

The Body



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# File 'lib/rack/lint.rb', line 638

def each
  @closed = false
  bytes = 0

  ## The Body must respond to +each+
  assert("Response body must respond to each") do
    @body.respond_to?(:each)
  end

  @body.each { |part|
    ## and must only yield String values.
    assert("Body yielded non-string value #{part.inspect}") {
      part.kind_of? String
    }
    bytes += Rack::Utils.bytesize(part)
    yield part
  }
  verify_content_length(bytes)

  ##
  ## The Body itself should not be an instance of String, as this will
  ## break in Ruby 1.9.
  ##
  ## If the Body responds to +close+, it will be called after iteration. If
  ## the body is replaced by a middleware after action, the original body
  ## must be closed first, if it responds to close.
  # XXX howto: assert("Body has not been closed") { @closed }


  ##
  ## If the Body responds to +to_path+, it must return a String
  ## identifying the location of a file whose contents are identical
  ## to that produced by calling +each+; this may be used by the
  ## server as an alternative, possibly more efficient way to
  ## transport the response.

  if @body.respond_to?(:to_path)
    assert("The file identified by body.to_path does not exist") {
      ::File.exist? @body.to_path
    }
  end

  ##
  ## The Body commonly is an Array of Strings, the application
  ## instance itself, or a File-like object.
end

- (Object) verify_content_length(bytes)



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# File 'lib/rack/lint.rb', line 625

def verify_content_length(bytes)
  if @head_request
    assert("Response body was given for HEAD request, but should be empty") {
      bytes == 0
    }
  elsif @content_length
    assert("Content-Length header was #{@content_length}, but should be #{bytes}") {
      @content_length == bytes.to_s
    }
  end
end