discourse/app/controllers/static_controller.rb

# frozen_string_literal: true

class StaticController < ApplicationController
  skip_before_action :check_xhr, :redirect_to_login_if_required, :redirect_to_profile_if_required
  skip_before_action :verify_authenticity_token,
                     only: %i[cdn_asset enter favicon llms_txt service_worker_asset]
  skip_before_action :preload_json, only: %i[cdn_asset enter favicon llms_txt service_worker_asset]
  skip_before_action :handle_theme, only: %i[cdn_asset enter favicon llms_txt service_worker_asset]

  before_action :apply_cdn_headers, only: %i[cdn_asset enter favicon service_worker_asset]

  PAGES_WITH_EMAIL_PARAM = %w[login password_reset signup]
  MODAL_PAGES = %w[password_reset signup]
  DEFAULT_PAGES = {
    "faq" => {
      redirect: "faq_url",
      topic_id: "guidelines_topic_id",
    },
    "tos" => {
      redirect: "tos_url",
      topic_id: "tos_topic_id",
    },
    "privacy" => {
      redirect: "privacy_policy_url",
      topic_id: "privacy_topic_id",
    },
  }
  CUSTOM_PAGES = {} # Add via `#add_topic_static_page` in plugin API

  def extract_redirect_param
    return "/" if params[:redirect].blank?

    uri = URI(params[:redirect])
    return "/" unless valid_redirect_uri?(uri)

    uri.query ? "#{uri.path}?#{uri.query}" : uri.path
  rescue URI::Error, ArgumentError
    "/"
  end

  def valid_redirect_uri?(uri)
    return false if uri.path.blank?
    return false if uri.path.starts_with?("#{Discourse.base_path}/login")
    return false if uri.host.present? && uri.host != URI(Discourse.base_url).host
    return false if !uri.path.match?(%r{\A/[^\.\s]*\z})

    true
  end

  def show
    if params[:id] == "login"
      destination = extract_redirect_param

      if current_user
        return redirect_to(path(destination), allow_other_host: false)
      elsif destination != "/"
        cookies[:destination_url] = path(destination)
      end
    elsif params[:id] == "signup" && current_user
      return redirect_to path("/")
    end

    if SiteSetting.login_required? && current_user.nil? && %w[faq guidelines].include?(params[:id])
      return redirect_to path("/login")
    end

    rename_faq =
      UpcomingChanges.enabled_for_user?(:experimental_rename_faq_to_guidelines, current_user)

    if rename_faq
      redirect_paths = %w[/rules /conduct]
      redirect_paths << "/faq" if SiteSetting.faq_url.blank?
      return redirect_to(path("/guidelines")) if redirect_paths.include?(request.path)
    end

    map = DEFAULT_PAGES.deep_merge(CUSTOM_PAGES)
    @page = params[:id]

    if map.has_key?(@page)
      site_setting_key = map[@page][:redirect]
      url = SiteSetting.get(site_setting_key) if site_setting_key
      return redirect_to(url, allow_other_host: true) if url.present?
    end

    # The /guidelines route ALWAYS shows our FAQ, ignoring the faq_url site setting.
    @page = "faq" if @page == "guidelines"

    # Don't allow paths like ".." or "/" or anything hacky like that
    @page = @page.gsub(/[^a-z0-9\_\-]/, "")

    if map.has_key?(@page)
      topic_id = map[@page][:topic_id]
      topic_id = instance_exec(&topic_id) if topic_id.is_a?(Proc)

      @topic = Topic.find_by_id(SiteSetting.get(topic_id))
      raise Discourse::NotFound unless @topic

      page_name =
        if @page == "faq"
          rename_faq ? "guidelines" : "faq"
        else
          @page
        end

      title_prefix =
        if I18n.exists?("js.#{page_name}")
          I18n.t("js.#{page_name}")
        else
          @topic.title
        end
      @title = "#{title_prefix} - #{SiteSetting.title}"
      @body = @topic.posts.first.cooked
      @faq_overridden = SiteSetting.faq_url.present?
      @experimental_rename_faq_to_guidelines = rename_faq

      render :show, layout: !request.xhr?, formats: [:html]
      return
    end

    @title = SiteSetting.title.dup

    if SiteSetting.short_site_description.present?
      @title << " - #{SiteSetting.short_site_description}"
    end

    if I18n.exists?("static.#{@page}")
      render html: I18n.t("static.#{@page}"), layout: !request.xhr?, formats: [:html]
      return
    end

    if PAGES_WITH_EMAIL_PARAM.include?(@page) && params[:email]
      cookies[:email] = { value: params[:email], expires: 1.day.from_now }
    end

    if lookup_context.find_all("static/#{@page}").any?
      render "static/#{@page}", layout: !request.xhr?, formats: [:html]
      return
    end

    if MODAL_PAGES.include?(@page)
      render html: nil, layout: true
      return
    end

    raise Discourse::NotFound
  end

  # This method just redirects to a given url.
  # It's used when an ajax login was successful but we want the browser to see
  # a post of a login form so that it offers to remember your password.
  def enter
    params.delete(:username)
    params.delete(:password)

    destination = extract_redirect_param
    allow_other_host = false

    # We need this to redirect the user back when Discourse Connect Provider is used.
    if cookies[:sso_destination_url]
      sso_url = cookies.delete(:sso_destination_url)

      begin
        uri = URI(sso_url)
        if valid_sso_redirect_uri?(uri)
          destination = sso_url
          allow_other_host = true
        end
      rescue URI::Error, ArgumentError
        # Invalid URI, ignore and use default destination
      end
    end

    destination = path(destination) if destination == "/"
    redirect_to(destination, allow_other_host:)
  end

  FAVICON = -"favicon"

  # We need to be able to draw our favicon on a canvas, this happens when you enable the feature
  # that draws the notification count on top of favicon (per user default off)
  #
  # With s3 the original upload is going to be stored at s3, we don't have a local copy of the favicon.
  # To allow canvas to work with s3 we are going to need to add special CORS headers and use
  # a special crossorigin hint on the original, this is not easily workable.
  #
  # Forcing all consumers to set magic CORS headers on a CDN is also not workable for us.
  #
  # So we cache the favicon in redis and serve it out real quick with
  # a huge expiry, we also cache these assets in nginx so it is bypassed if needed
  def favicon
    is_asset_path

    hijack do
      data =
        DistributedMemoizer.memoize("FAVICON#{SiteIconManager.favicon_url}", 60 * 30) do
          favicon = SiteIconManager.favicon
          next "" unless favicon

          if Discourse.store.external?
            begin
              file =
                FileHelper.download(
                  Discourse.store.cdn_url(favicon.url),
                  max_file_size: favicon.filesize,
                  tmp_file_name: FAVICON,
                  follow_redirect: true,
                )

              file&.read || ""
            rescue => e
              ProblemCheckTracker[:bad_favicon_url].problem!
              Rails.logger.debug("Failed to fetch favicon #{favicon.url}: #{e}\n#{e.backtrace}")
              ""
            ensure
              file&.unlink
            end
          else
            File.read(Rails.public_path.join(favicon.url[1..-1]))
          end
        end

      if data.bytesize == 0
        @@default_favicon ||= File.read(Rails.root + "public/images/default-favicon.png")
        response.headers["Content-Length"] = @@default_favicon.bytesize.to_s
        render body: @@default_favicon, content_type: "image/png"
      else
        immutable_for 1.year
        response.headers["Expires"] = 1.year.from_now.httpdate
        response.headers["Content-Length"] = data.bytesize.to_s
        response.headers["Last-Modified"] = Time.new(2000, 01, 01).httpdate
        render body: data, content_type: "image/png"
      end
    end
  end

  def llms_txt
    upload = SiteSetting.llms_txt
    return head(:not_found) if upload.blank?

    if Discourse.store.external?
      content =
        Discourse
          .cache
          .fetch("llms_txt_content:#{upload.sha1}") do
            Discourse.store.download_safe(upload)&.path&.then { |path| File.read(path) }
          end
      return head(:not_found) if content.blank?

      render plain: content, content_type: "text/plain"
    else
      path = Discourse.store.path_for(upload)
      return head(:not_found) if path.blank? || !File.exist?(path)

      send_file(path, type: "text/plain", disposition: "inline")
    end
  end

  def cdn_asset
    is_asset_path

    serve_asset
  end

  def service_worker_asset
    is_asset_path

    respond_to do |format|
      format.js do
        # https://github.com/w3c/ServiceWorker/blob/master/explainer.md#updating-a-service-worker
        # Maximum cache that the service worker will respect is 24 hours.
        # However, ensure that these may be cached and served for longer on servers.
        immutable_for 1.year
        render "service-worker"
      end
    end
  end

  protected

  def valid_sso_redirect_uri?(uri)
    return false unless SiteSetting.enable_discourse_connect_provider
    return false if uri.host.blank?

    provider_domains =
      SiteSetting
        .discourse_connect_provider_secrets
        .split("\n")
        .map { |row| row.split("|", 2).first }
        .compact

    provider_domains.any? { |domain| WildcardDomainChecker.check_domain(domain, uri.host) }
  end

  def serve_asset(suffix = nil)
    path = File.expand_path(Rails.root + "public/assets/#{params[:path]}#{suffix}")

    # SECURITY what if path has /../
    raise Discourse::NotFound unless path.start_with?(Rails.root.to_s + "/public/assets")

    response.headers["Expires"] = 1.year.from_now.httpdate
    response.headers["Access-Control-Allow-Origin"] = params[:origin] if params[:origin]

    begin
      response.headers["Last-Modified"] = File.ctime(path).httpdate
    rescue Errno::ENOENT
      begin
        if GlobalSetting.fallback_assets_path.present?
          path = File.expand_path("#{GlobalSetting.fallback_assets_path}/#{params[:path]}#{suffix}")
          response.headers["Last-Modified"] = File.ctime(path).httpdate
        else
          raise
        end
      rescue Errno::ENOENT
        expires_in 1.second, public: true, must_revalidate: false

        render plain: "can not find #{params[:path]}", status: :not_found
        return
      end
    end

    response.headers["Content-Length"] = File.size(path).to_s

    yield if block_given?

    immutable_for 1.year

    # disable NGINX mucking with transfer
    request.env["sendfile.type"] = ""

    opts = { disposition: nil }
    opts[:type] = "application/javascript" if params[:path] =~ /\.js$/
    send_file(path, opts)
  end
end