Class: AtomicLti::OpenIdMiddleware

Inherits:
Object
  • Object
show all
Defined in:
lib/atomic_lti/open_id_middleware.rb

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ OpenIdMiddleware

Returns a new instance of OpenIdMiddleware.



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# File 'lib/atomic_lti/open_id_middleware.rb', line 7

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 219

def call(env)
  request = Rack::Request.new(env)
  if init_paths.include?(request.path)
    handle_init(request)
  elsif matches_redirect?(request)
    handle_redirect(request)
  elsif matches_target_link?(request) && request.params["id_token"].present?
    handle_lti_launch(env, request)
  else
    @app.call(env)
  end
end

#error!(body = "Error", status = 500, headers = { "Content-Type" => "text/html" }) ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 215

def error!(body = "Error", status = 500, headers = { "Content-Type" => "text/html" })
  [status, headers, [body]]
end

#handle_init(request) ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 23

def handle_init(request)
  platform = AtomicLti::Platform.find_by(iss: request.params["iss"])
  if !platform
    raise AtomicLti::Exceptions::NoLTIPlatform.new(iss: request.params["iss"])
  end

  nonce, state = AtomicLti::OpenId.generate_state

  headers = { "Content-Type" => "text/html" }
  Rack::Utils.set_cookie_header!(
    headers, "#{OPEN_ID_COOKIE_PREFIX}storage",
    { value: "1", path: "/", max_age: 365.days, http_only: false, secure: true, same_site: "None", partitioned: true }
  )
  Rack::Utils.set_cookie_header!(
    headers, "#{OPEN_ID_COOKIE_PREFIX}#{state}",
    { value: 1, path: "/", max_age: 1.minute, http_only: false, secure: true, same_site: "None", partitioned: true }
  )

  # Ensure our cookies are partitioned.  This can be removed once our Rack version
  # understands the partitioned: argument above.
  headers[Rack::SET_COOKIE] = partition_cookies(headers[Rack::SET_COOKIE])

  redirect_uri = [request.base_url, AtomicLti.oidc_redirect_path].join
  response_url = build_oidc_response(request, state, nonce, redirect_uri)

  if request.cookies.present? || !AtomicLti.enforce_csrf_protection
    # we know cookies will work, so redirect
    headers["Location"] = response_url

    [302, headers, ["Found"]]
  else
    # cookies might not work, so render our javascript form
    if request.params["lti_storage_target"].present? && AtomicLti.use_post_message_storage
      lti_storage_params = build_lti_storage_params(request, platform)
    end

    html = ApplicationController.renderer.render(
      :html,
      layout: false,
      template: "atomic_lti/shared/init",
      assigns: {
        settings: {
          state: state,
          responseUrl: response_url,
          ltiStorageParams: lti_storage_params,
          relaunchInitUrl: relaunch_init_url(request),
          privacyPolicyUrl: AtomicLti.privacy_policy_url,
          privacyPolicyMessage: AtomicLti.privacy_policy_message,
          openIdCookiePrefix: OPEN_ID_COOKIE_PREFIX,
        },
      },
    )

    [200, headers, [html]]
  end
end

#handle_lti_launch(env, request) ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 179

def handle_lti_launch(env, request)
  id_token_decoded, state, state_verified = validate_launch(request, true, true)

  id_token = request.params["id_token"]
  update_install(id_token: id_token_decoded)
  update_platform_instance(id_token: id_token_decoded)
  update_deployment(id_token: id_token_decoded)
  update_lti_context(id_token: id_token_decoded)

  errors = id_token_decoded.dig(AtomicLti::Definitions::TOOL_PLATFORM_CLAIM, "errors")
  if errors.present? && !errors["errors"].empty?
    Rails.logger.error("Detected errors in lti launch: #{errors}, id_token: #{id_token}")
  end

  env["atomic.validated.decoded_id_token"] = id_token_decoded
  env["atomic.validated.id_token"] = id_token

  platform = AtomicLti::Platform.find_by!(iss: id_token_decoded["iss"])

  # Add the values needed to do client side validate to the environment
  env["atomic.validated.state_validation"] = {
    state: state,
    state_verified: state_verified,
  }

  if !state_verified && AtomicLti.use_post_message_storage
    env["atomic.validated.state_validation"][:lti_storage_params] =
      build_lti_storage_params(request, platform)
  end

  # Delete the state cookie
  status, headers, body = @app.call(env)
  # Rack::Utils.delete_cookie_header(headers, "#{OPEN_ID_COOKIE_PREFIX}#{state}")
  [status, headers, body]
end

#handle_redirect(request) ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 106

def handle_redirect(request)
  id_token_decoded, _state, _state_verified = validate_launch(request, false, false)

  uri = URI(request.url)
  # Technically the target_link_uri is not required and the certification suite
  # does not send it on a deep link launch. Typically target link uri will be present
  # but at least for the certification suite we have to have a backup default
  # value that can be set in the configuration of Atomic LTI using
  # the default_deep_link_path
  target_link_uri = id_token_decoded[AtomicLti::Definitions::TARGET_LINK_URI_CLAIM] ||
    File.join("#{uri.scheme}://#{uri.host}", AtomicLti.default_deep_link_path)

  target = URI.parse(target_link_uri)

  # Optionally update the target link host to match the redirect host
  if AtomicLti.update_target_link_host && target.host != uri.host
    target.host = uri.host
  end

  # We want to strip out the redirect path params from the request params
  # so that we can support having the redirect path be the same as the
  # launch path, only differentiated by a query parameter. This is needed
  # because socialize journals redirects straight to /lti_launches and we
  # have preexisting lti keys that we won't get to migrate and can't break
  redirect_uri = URI.parse(AtomicLti.oidc_redirect_path)
  redirect_path_params = if redirect_uri.query
                           CGI.parse(redirect_uri.query)
                         else
                           {}
                         end

  launch_params = request.params.except(*redirect_path_params.keys)

  html = ApplicationController.renderer.render(
    :html,
    layout: false,
    template: "atomic_lti/shared/redirect",
    assigns: {
      launch_params: launch_params,
      launch_url: target,
    },
  )

  [200, { "Content-Type" => "text/html" }, [html]]
end

#init_paths ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 11

def init_paths
  [
    AtomicLti.oidc_init_path,
  ]
end

#matches_redirect?(request) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/atomic_lti/open_id_middleware.rb', line 152

def matches_redirect?(request)
  if AtomicLti.oidc_redirect_path.blank?
    raise AtomicLti::Exceptions::ConfigurationError.new("AtomicLti.oidc_redirect_path is not configured")
  end

  redirect_uri = URI.parse(AtomicLti.oidc_redirect_path)
  redirect_path_params = if redirect_uri.query
                           CGI.parse(redirect_uri.query)
                         else
                           {}
                         end

  matches_redirect_path = request.path == redirect_uri.path

  return false if !matches_redirect_path

  params_match = redirect_path_params.all? { |key, values| request.params[key] == values.first }

  matches_redirect_path && params_match
end

#matches_target_link?(request) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/atomic_lti/open_id_middleware.rb', line 173

def matches_target_link?(request)
  AtomicLti.target_link_path_prefixes.any? do |prefix|
    request.path.starts_with? prefix
  end || request.path.starts_with?(AtomicLti.default_deep_link_path)
end

#redirect_paths ⇒ Object 



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# File 'lib/atomic_lti/open_id_middleware.rb', line 17

def redirect_paths
  [
    AtomicLti.oidc_redirect_path,
  ]
end

#validate_launch(request, validate_target_link_url, destroy_state) ⇒ Object

Raises:



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# File 'lib/atomic_lti/open_id_middleware.rb', line 80

def validate_launch(request, validate_target_link_url, destroy_state)
  # Validate and decode id_token
  raise AtomicLti::Exceptions::NoLTIToken if request.params["id_token"].blank?

  id_token_decoded = AtomicLti::Authorization.validate_token(request.params["id_token"])

  raise AtomicLti::Exceptions::InvalidLTIToken.new if id_token_decoded.nil?

  # Validate id token contents
  AtomicLti::Lti.validate!(id_token_decoded, request.url, validate_target_link_url)

  # Check for the state cookie
  state_verified = false
  state = request.params["state"]
  if request.cookies["open_id_#{state}"]
    state_verified = true
  end

  # Validate the state and nonce
  if !AtomicLti::OpenId.validate_state(id_token_decoded["nonce"], state, destroy_state)
    raise AtomicLti::Exceptions::OpenIDStateError.new("Invalid OIDC state.")
  end

  [id_token_decoded, state, state_verified]
end