openstreetmap-website/app/controllers/api_controller.rb

class ApiController < ApplicationController
  skip_before_action :verify_authenticity_token

  private

  ##
  # Set default request format to xml unless a client requests a specific format,
  # which can be done via (a) URL suffix and/or (b) HTTP Accept header, where
  # the URL suffix always takes precedence over the Accept header.
  def set_default_request_format
    unless params[:format]
      accept_header = request.headers["HTTP_ACCEPT"]
      if accept_header.nil?
        # e.g. unit tests don't set an Accept: header by default, force XML in this case
        request.format = "xml"
        return
      end

      req_mimetypes = []

      # Some clients (JOSM) send Accept headers which cannot be parsed by Rails, example: *; q=.2
      # To be fair, JOSM's Accept header doesn't adhere to RFC 7231, section 5.3.1, et al. either
      # As a workaround for backwards compatibility, we're assuming XML format
      begin
        req_mimetypes = Mime::Type.parse(accept_header)
      rescue Mime::Type::InvalidMimeType
        request.format = "xml"
        return
      end

      # req_mimetypes contains all Accept header MIME types with descending priority
      req_mimetypes.each do |mime|
        if mime.symbol == :xml
          request.format = "xml"
          break
        end

        if mime.symbol == :json
          request.format = "json"
          break
        end

        # Any format, not explicitly requesting XML or JSON -> assume XML as default
        if mime == "*/*"
          request.format = "xml"
          break
        end

        # In case the client requests some other format besides XML, JSON and */*,
        # we deliberately don't set request.format. The framework will return an
        # ActionController::UnknownFormat error to the client later on in this case.
      end
    end
  end

  def authorize(realm = "Web Password", errormessage = "Couldn't authenticate you")
    # make the current_user object from any auth sources we have
    setup_user_auth

    # handle authenticate pass/fail
    unless current_user
      # no auth, the user does not exist or the password was wrong
      response.headers["WWW-Authenticate"] = "Basic realm=\"#{realm}\""
      render :plain => errormessage, :status => :unauthorized
      false
    end
  end

  def current_ability
    # Use capabilities from the oauth token if it exists and is a valid access token
    if Authenticator.new(self, [:token]).allow?
      ApiAbility.new(nil).merge(ApiCapability.new(current_token))
    else
      ApiAbility.new(current_user)
    end
  end

  def deny_access(_exception)
    if current_token
      set_locale
      report_error t("oauth.permissions.missing"), :forbidden
    elsif current_user
      head :forbidden
    else
      realm = "Web Password"
      errormessage = "Couldn't authenticate you"
      response.headers["WWW-Authenticate"] = "Basic realm=\"#{realm}\""
      render :plain => errormessage, :status => :unauthorized
    end
  end

  def gpx_status
    status = database_status
    status = "offline" if status == "online" && Settings.status == "gpx_offline"
    status
  end

  ##
  # sets up the current_user for use by other methods. this is mostly called
  # from the authorize method, but can be called elsewhere if authorisation
  # is optional.
  def setup_user_auth
    # try and setup using OAuth
    unless Authenticator.new(self, [:token]).allow?
      username, passwd = get_auth_data # parse from headers
      # authenticate per-scheme
      self.current_user = if username.nil?
                            nil # no authentication provided - perhaps first connect (client should retry after 401)
                          elsif username == "token"
                            User.authenticate(:token => passwd) # preferred - random token for user from db, passed in basic auth
                          else
                            User.authenticate(:username => username, :password => passwd) # basic auth
                          end
    end

    # have we identified the user?
    if current_user
      # check if the user has been banned
      user_block = current_user.blocks.active.take
      unless user_block.nil?
        set_locale
        if user_block.zero_hour?
          report_error t("application.setup_user_auth.blocked_zero_hour"), :forbidden
        else
          report_error t("application.setup_user_auth.blocked"), :forbidden
        end
      end

      # if the user hasn't seen the contributor terms then don't
      # allow editing - they have to go to the web site and see
      # (but can decline) the CTs to continue.
      if !current_user.terms_seen && flash[:skip_terms].nil?
        set_locale
        report_error t("application.setup_user_auth.need_to_see_terms"), :forbidden
      end
    end
  end
end