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, InputWrapper, LintError

Instance Method Summary collapse

Methods included from Assertion

#assert

Constructor Details

#initialize(app) ⇒ Lint

Returns a new instance of Lint.



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# File 'lib/rack/lint.rb', line 6

def initialize(app)
  @app = app
end

Instance Method Details

#call(env = nil) ⇒ Object

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



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# File 'lib/rack/lint.rb', line 32

def call(env=nil)
  ## 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
  ## and the *body*.
  check_content_type status, headers
  [status, headers, self]
end

#check_content_type(status, headers) ⇒ Object

The Content-Type



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# File 'lib/rack/lint.rb', line 343

def check_content_type(status, headers)
  headers.each { |key, value|
    ## There must be a <tt>Content-Type</tt>, except when the
    ## +Status+ is 204 or 304, in which case there must be none
    ## given.
    if key.downcase == "content-type"
      assert("Content-Type header found in #{status} response, not allowed"){
        not [204, 304].include? status.to_i
      }
      return
    end
  }
  assert("No Content-Type header found") {
    [201, 204, 304].include? status.to_i
  }
end

#check_env(env) ⇒ Object

The Environment



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# File 'lib/rack/lint.rb', line 52

def check_env(env)
  ## The environment must be an true instance of Hash (no
  ## subclassing allowed) 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.instance_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.

  ## <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.

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

  ## <tt>rack.version</tt>:: The Array [0,1], representing this version of Rack.
  ## <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).

  ## 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 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.instance_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"].instance_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"]

  ## * The <tt>REQUEST_METHOD</tt> must be one of +GET+, +POST+, +PUT+,
  ##   +DELETE+, +HEAD+, +OPTIONS+, +TRACE+.
  assert("REQUEST_METHOD unknown: #{env["REQUEST_METHOD"]}") {
    %w[GET POST PUT DELETE
       HEAD OPTIONS TRACE].include?(env["REQUEST_METHOD"])
  }

  ## * 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

#check_error(error) ⇒ Object

The Error Stream



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# File 'lib/rack/lint.rb', line 261

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

#check_headers(header) ⇒ Object

The Headers



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# File 'lib/rack/lint.rb', line 309

def check_headers(header)
  ## The header must respond to each, and yield values of key and value.
  assert("header should respond to #each") { header.respond_to? :each }
  header.each { |key, value|
    ## The header keys must be Strings.
    assert("header key must be a string, was #{key.class}") {
      key.instance_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 respond to #each.
    assert("header values must respond to #each") { value.respond_to? :each }
    value.each { |item|
      ## The values passed on #each must be Strings
      assert("header values must consist of Strings") {
        item.instance_of?(String)
      }
      ## and not contain characters below 037.
      assert("invalid header value #{key}: #{item.inspect}") {
        item !~ /[\000-\037]/
      }
    }
  }
end

#check_input(input) ⇒ Object

The Input Stream



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# File 'lib/rack/lint.rb', line 198

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

#check_status(status) ⇒ Object

The Status



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# File 'lib/rack/lint.rb', line 303

def check_status(status)
  ## The status, if parsed as integer (+to_i+), must be bigger than 100.
  assert("Status must be >100 seen as integer") { status.to_i > 100 }
end

#close ⇒ Object 



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# File 'lib/rack/lint.rb', line 380

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

#each ⇒ Object

The Body



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# File 'lib/rack/lint.rb', line 361

def each
  @closed = false
  ## The Body must respond to #each
  @body.each { |part|
    ## and must only yield String values.
    assert("Body yielded non-string value #{part.inspect}") {
      part.instance_of? String
    }
    yield part
  }
  ## 
  ## If the Body responds to #close, it will be called after iteration.
  # XXX howto: assert("Body has not been closed") { @closed }

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