module Sprockets::Server - sprockets-2.11.3 Documentation

# module Sprockets::Server

`Server` is a concern mixed into `Environment` and `Index` that provides a Rack compatible `call` interface and url generation helpers.

### Public Instance Methods

call(env) click to toggle source

`call` implements the Rack 1.x specification which accepts an `env` Hash and returns a three item tuple with the status code, headers, and body.

Mapping your environment at a url prefix will serve all assets in the path.

    map "/assets" do
      run Sprockets::Environment.new
    end

A request for `“/assets/foo/bar.js”` will search your environment for `“foo/bar.js”`.

    # File lib/sprockets/server.rb, line 22
    def call(env)
      start_time = Time.now.to_f
      time_elapsed = lambda { ((Time.now.to_f - start_time) * 1000).to_i }

      msg = "Served asset #{env['PATH_INFO']} -"

      # Mark session as "skipped" so no `Set-Cookie` header is set
      env['rack.session.options'] ||= {}
      env['rack.session.options'][:defer] = true
      env['rack.session.options'][:skip] = true

      # Extract the path from everything after the leading slash
      path = unescape(env['PATH_INFO'].to_s.sub(/^\//, ''))

      # Strip fingerprint
      if fingerprint = path_fingerprint(path)
        path = path.sub("-#{fingerprint}", '')
      end

      # URLs containing a `".."` are rejected for security reasons.
      if forbidden_request?(path)
        return forbidden_response
      end

      # Look up the asset.
      asset = find_asset(path, :bundle => !body_only?(env))

      # `find_asset` returns nil if the asset doesn't exist
      if asset.nil?
        logger.info "#{msg} 404 Not Found (#{time_elapsed.call}ms)"

        # Return a 404 Not Found
        not_found_response

      # Check request headers `HTTP_IF_NONE_MATCH` against the asset digest
      elsif etag_match?(asset, env)
        logger.info "#{msg} 304 Not Modified (#{time_elapsed.call}ms)"

        # Return a 304 Not Modified
        not_modified_response(asset, env)

      else
        logger.info "#{msg} 200 OK (#{time_elapsed.call}ms)"

        # Return a 200 with the asset contents
        ok_response(asset, env)
      end
    rescue Exception => e
      logger.error "Error compiling asset #{path}:"
      logger.error "#{e.class.name}: #{e.message}"

      case content_type_of(path)
      when "application/javascript"
        # Re-throw JavaScript asset exceptions to the browser
        logger.info "#{msg} 500 Internal Server Error\n\n"
        return javascript_exception_response(e)
      when "text/css"
        # Display CSS asset exceptions in the browser
        logger.info "#{msg} 500 Internal Server Error\n\n"
        return css_exception_response(e)
      else
        raise
      end
    end

### Private Instance Methods

body_only?(env) click to toggle source

Test if `?body=1` or `body=true` query param is set

    # File lib/sprockets/server.rb, line 182
    def body_only?(env)
      env["QUERY_STRING"].to_s =~ /body=(1|t)/
    end

css_exception_response(exception) click to toggle source

Returns a CSS response that hides all elements on the page and displays the exception

    # File lib/sprockets/server.rb, line 116
    def css_exception_response(exception)
      message   = "\n#{exception.class.name}: #{exception.message}"
      backtrace = "\n  #{exception.backtrace.first}"

      body = <<-CSS
        html {
          padding: 18px 36px;
        }

        head {
          display: block;
        }

        body {
          margin: 0;
          padding: 0;
        }

        body > * {
          display: none !important;
        }

        head:after, body:before, body:after {
          display: block !important;
        }

        head:after {
          font-family: sans-serif;
          font-size: large;
          font-weight: bold;
          content: "Error compiling CSS asset";
        }

        body:before, body:after {
          font-family: monospace;
          white-space: pre-wrap;
        }

        body:before {
          font-weight: bold;
          content: "#{escape_css_content(message)}";
        }

        body:after {
          content: "#{escape_css_content(backtrace)}";
        }
      CSS

      [ 200, { "Content-Type" => "text/css;charset=utf-8", "Content-Length" => Rack::Utils.bytesize(body).to_s }, [ body ] ]
    end

escape_css_content(content) click to toggle source

Escape special characters for use inside a CSS content(“…”) string

    # File lib/sprockets/server.rb, line 168
    def escape_css_content(content)
      content.
        gsub('\', '\\005c ').
        gsub("\n", '\\000a ').
        gsub('"',  '\\0022 ').
        gsub('/',  '\\002f ')
    end

etag(asset) click to toggle source

Helper to quote the assets digest for use as an ETag.

    # File lib/sprockets/server.rb, line 243
    def etag(asset)
      %Q("#{asset.digest}")
    end

etag_match?(asset, env) click to toggle source

Compare the requests `HTTP_IF_NONE_MATCH` against the assets digest

    # File lib/sprockets/server.rb, line 177
    def etag_match?(asset, env)
      env["HTTP_IF_NONE_MATCH"] == etag(asset)
    end

forbidden_request?(path) click to toggle source

    # File lib/sprockets/server.rb, line 88
    def forbidden_request?(path)
      # Prevent access to files elsewhere on the file system
      #
      #     http://example.org/assets/../../../etc/passwd
      #
      path.include?("..") || Pathname.new(path).absolute?
    end

forbidden_response() click to toggle source

Returns a 403 Forbidden response tuple

    # File lib/sprockets/server.rb, line 97
    def forbidden_response
      [ 403, { "Content-Type" => "text/plain", "Content-Length" => "9" }, [ "Forbidden" ] ]
    end

headers(env, asset, length) click to toggle source

    # File lib/sprockets/server.rb, line 196
    def headers(env, asset, length)
      Hash.new.tap do |headers|
        # Set content type and length headers
        headers["Content-Type"]   = asset.content_type
        headers["Content-Length"] = length.to_s

        # Set caching headers
        headers["Cache-Control"]  = "public"
        headers["Last-Modified"]  = asset.mtime.httpdate
        headers["ETag"]           = etag(asset)

        # If the request url contains a fingerprint, set a long
        # expires on the response
        if path_fingerprint(env["PATH_INFO"])
          headers["Cache-Control"] << ", max-age=31536000"

        # Otherwise set `must-revalidate` since the asset could be modified.
        else
          headers["Cache-Control"] << ", must-revalidate"
        end
      end
    end

javascript_exception_response(exception) click to toggle source

Returns a JavaScript response that re-throws a Ruby exception in the browser

    # File lib/sprockets/server.rb, line 108
    def javascript_exception_response(exception)
      err  = "#{exception.class.name}: #{exception.message}"
      body = "throw Error(#{err.inspect})"
      [ 200, { "Content-Type" => "application/javascript", "Content-Length" => Rack::Utils.bytesize(body).to_s }, [ body ] ]
    end

not_found_response() click to toggle source

Returns a 404 Not Found response tuple

    # File lib/sprockets/server.rb, line 102
    def not_found_response
      [ 404, { "Content-Type" => "text/plain", "Content-Length" => "9", "X-Cascade" => "pass" }, [ "Not found" ] ]
    end

not_modified_response(asset, env) click to toggle source

Returns a 304 Not Modified response tuple

    # File lib/sprockets/server.rb, line 187
    def not_modified_response(asset, env)
      [ 304, {}, [] ]
    end

ok_response(asset, env) click to toggle source

Returns a 200 OK response tuple

    # File lib/sprockets/server.rb, line 192
    def ok_response(asset, env)
      [ 200, headers(env, asset, asset.length), asset ]
    end

path_fingerprint(path) click to toggle source

Gets digest fingerprint.

    "foo-0aa2105d29558f3eb790d411d7d8fb66.js"
    # => "0aa2105d29558f3eb790d411d7d8fb66"

    # File lib/sprockets/server.rb, line 224
    def path_fingerprint(path)
      path[/-([0-9a-f]{7,40})\.[^.]+\z/, 1]
    end

unescape(str) click to toggle source

    # File lib/sprockets/server.rb, line 231
    def unescape(str)
      str = URI::DEFAULT_PARSER.unescape(str)
      str.force_encoding(Encoding.default_internal) if Encoding.default_internal
      str
    end