release: 2.1.1

- including review suggestions from @jgraichen

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 *.lock
 pkg/*
+.yardoc

.rubocop.yml

@@ -0,0 +1,87 @@
+AllCops:
+  TargetRubyVersion: '2.3'
+
+Gemspec/OrderedDependencies:
+  Enabled: false
+
+Layout/EmptyLineAfterGuardClause:
+  Enabled: false
+
+# allows nicer usage of private_class_method
+Layout/EmptyLinesAroundArguments:
+  Enabled: false
+
+Layout/HashAlignment:
+  Enabled: false
+
+Layout/LeadingEmptyLines:
+  Enabled: false
+
+Layout/LineLength:
+  Max: 200
+
+Layout/SpaceInsideHashLiteralBraces:
+  Enabled: false
+
+Metrics/AbcSize:
+  Enabled: false
+
+Metrics/BlockLength:
+  Enabled: false
+
+Metrics/ClassLength:
+  Enabled: false
+
+Metrics/CyclomaticComplexity:
+  Enabled: false
+
+Metrics/MethodLength:
+  Enabled: false
+
+Metrics/PerceivedComplexity:
+  Enabled: false
+
+Naming/MethodParameterName:
+  Enabled: false
+
+Naming/MemoizedInstanceVariableName:
+  Enabled: false
+
+Style/ConditionalAssignment:
+  Enabled: false
+
+Style/Documentation:
+  Enabled: false
+
+Style/FormatStringToken:
+  Enabled: false
+
+Style/FrozenStringLiteralComment:
+  Enabled: false
+
+Style/GuardClause:
+  Enabled: false
+
+Style/HashEachMethods:
+  Enabled: true
+
+Style/HashTransformKeys:
+  Enabled: true
+
+Style/HashTransformValues:
+  Enabled: true
+
+Style/IdenticalConditionalBranches:
+  Enabled: false
+
+Style/InverseMethods:
+  Enabled: false
+
+Style/NegatedIf:
+  Enabled: false
+
+Style/RescueModifier:
+  Enabled: false
+
+Style/SymbolArray:
+  Enabled: false

.solargraph.yml

@@ -0,0 +1,16 @@
+---
+include:
+- "**/*.rb"
+- "bin/dyndnsd"
+exclude:
+- spec/**/*
+- test/**/*
+- vendor/**/*
+- ".bundle/**/*"
+require: []
+domains: []
+reporters:
+- rubocop
+- require_not_found
+require_paths: []
+max_files: 5000

.travis.yml

@@ -1,11 +1,12 @@
+---
+os: linux
 language: ruby
-
 rvm:
-  - 2.0.0
-  - 1.9.3
+- 2.7
+- 2.6
+- 2.5
+- 2.4
+- 2.3
 
-gemfile:
-  - Gemfile
-
-before_install:
-  - gem install bundler
+script:
+- bundle exec rake travis

CHANGELOG.md

@@ -0,0 +1,93 @@
+# Changelog
+
+## 2.1.1 (March 1, 2020)
+
+IMPROVEMENTS:
+
+- Fix potential `nil` cases detected by [Sorbet](https://sorbet.org) including refactorings
+
+## 2.1.0 (March 1, 2020)
+
+IMPROVEMENTS:
+
+- Add Ruby 2.7 support
+- Add [solargraph](https://github.com/castwide/solargraph) to dev tooling as Ruby Language Server usable e.g. for IDEs (used solargraph version not compatible with Ruby 2.7 as bundler-audit 0.6.x requires old `thor` gem)
+- Document code using YARD tags, e.g. for type information and better code completion
+
+## 2.0.0 (January 25, 2019)
+
+IMPROVEMENTS:
+
+- Drop Ruby 2.2 and lower support
+- Better protocol compliance by returning `badauth` in response body on HTTP 401 errors
+- Better code maintainability by refactorings
+- Update dependencies, mainly `rack` to new major version 2
+- Add Ruby 2.5 and Ruby 2.6 support
+- Add experimental [OpenTracing](https://opentracing.io/) support with [CNCF Jaeger](https://github.com/jaegertracing/jaeger)
+- Support host offlining by deleting the associated DNS records
+- Add textfile reporter to write Graphite-style metrics (also compatible with [Prometheus](https://prometheus.io/)) into a file
+
+## 1.6.1 (October 31, 2017)
+
+IMPROVEMENTS:
+
+- Fix broken password check affecting all previous releases
+
+## 1.6.0 (December 7, 2016)
+
+IMPROVEMENTS:
+
+- Support providing an IPv6 address in addition to a IPv4 for the same hostname
+
+## 1.5.0 (November 30, 2016)
+
+IMPROVEMENTS:
+
+- Drop Ruby 1.8.7 support
+- Pin `json` gem to allow supporting Ruby 1.9.3
+- Support determining effective client IP address also from `X-Real-IP` header
+
+## 1.4.0 (November 27, 2016)
+
+IMPROVEMENTS:
+
+- Pin `rack` gem to allow supporting Ruby versions < 2.2.2
+- Support IPv6 addresses
+
+## 1.3.0 (October 8, 2013)
+
+IMPROVEMENTS:
+
+- Handle `SIGTERM` \*nix signal properly and shutdown the daemon
+
+## 1.2.2 (June 8, 2013)
+
+IMPROVEMENTS:
+
+- Add proper logging to the provided init script for dyndnsd.rb
+
+## 1.2.1 (June 5, 2013)
+
+IMPROVEMENTS:
+
+- Fix bug in previous release related to metrics preventing startup
+
+## 1.2.0 (May 29, 2013)
+
+IMPROVEMENTS:
+
+- Support sending metrics to graphite via undocumented `graphite:` section in configuration file
+
+## 1.1.0 (April 30, 2013)
+
+IMPROVEMENTS:
+
+- Support dropping priviliges on startup, also affects external commands run
+- Add [metriks](https://github.com/eric/metriks) support for basic metrics in the process title
+- Detach from child processes running external commands to avoid zombie processes
+
+## 1.0.0 (April 28, 2013)
+
+NEW FEATURES:
+
+- Initial 1.0 release

README.md

@@ -1,16 +1,18 @@
 # dyndnsd.rb
 
-[![Build Status](https://travis-ci.org/cmur2/dyndnsd.png)](https://travis-ci.org/cmur2/dyndnsd)
+[![Build Status](https://travis-ci.org/cmur2/dyndnsd.svg?branch=master)](https://travis-ci.org/cmur2/dyndnsd) [![Dependencies](https://badges.depfu.com/badges/4f25da8493f7a29f652ac892fbf9227b/overview.svg)](https://depfu.com/github/cmur2/dyndnsd)
 
 A small, lightweight and extensible DynDNS server written with Ruby and Rack.
 
 ## Description
 
-dyndnsd.rb aims to implement a small [DynDNS-compliant](http://dyn.com/support/developers/api/) server in Ruby supporting IPv4 and IPv6 addresses. It has an integrated user and hostname database in it's configuration file that is used for authentication and authorization. Besides talking the DynDNS protocol it is able to invoke an so-called *updater*, a small Ruby module that takes care of supplying the current host => ip mapping to a DNS server.
+dyndnsd.rb aims to implement a small [DynDNS-compliant](https://help.dyn.com/remote-access-api/) server in Ruby supporting IPv4 and IPv6 addresses. It has an integrated user and hostname database in it's configuration file that is used for authentication and authorization. Besides talking the DynDNS protocol it is able to invoke a so-called *updater*, a small Ruby module that takes care of supplying the current hostname => ip mapping to a DNS server.
 
-There is currently one updater shipped with dyndnsd.rb `command_with_bind_zone` that writes out a zone file in BIND syntax onto the current system and invokes a user-supplied command afterwards that is assumed to trigger the DNS server (not necessarily BIND since it's zone files are read by other DNS servers too) to reload it's zone configuration.
+There is currently one updater shipped with dyndnsd.rb `command_with_bind_zone` that writes out a zone file in BIND syntax onto the current system and invokes a user-supplied command afterwards that is assumed to trigger the DNS server (not necessarily BIND since it's zone files are read by other DNS servers, too) to reload it's zone configuration.
 
-Because of the mechanisms used dyndnsd.rb is known to work only on \*nix systems.
+Because of the mechanisms used, dyndnsd.rb is known to work only on \*nix systems.
+
+See the [changelog](CHANGELOG.md) before upgrading. The older version 1.x of dyndnsd.rb is still available on [branch dyndnsd-1.x](https://github.com/cmur2/dyndnsd/tree/dyndnsd-1.x).
 
 ## General Usage
 
@@ -101,7 +103,7 @@ Please provide ideas if you are using dyndnsd.rb with other DNS servers :)
 
 The update URL you want to tell your clients (humans or scripts ^^) consists of the following
 
-	http[s]://[USER]:[PASSWORD]@[DOMAIN]:[PORT]/nic/update?hostname=[HOSTNAMES]&myip=[MYIP]
+	http[s]://[USER]:[PASSWORD]@[DOMAIN]:[PORT]/nic/update?hostname=[HOSTNAMES]&myip=[MYIP]&myip6=[MYIP6]
 
 where:
 
@@ -110,7 +112,8 @@ where:
 * DOMAIN should match what you defined in your config.yaml as domain but may be anything else when using a webserver as proxy
 * PORT depends on your (webserver/proxy) settings
 * HOSTNAMES is a required list of comma separated FQDNs (they all have to end with your config.yaml domain) the user wants to update
-* MYIP is optional and the HTTP client's address will be used if missing
+* MYIP is optional and the HTTP client's IP address will be used if missing
+* MYIP6 is optional but if present also requires presence of MYIP
 
 ### IP address determination
 
@@ -130,6 +133,83 @@ Use a webserver as a proxy to handle SSL and/or multiple listen addresses and po
 
 The [Debian 6 init.d script](init.d/debian-6-dyndnsd) assumes that dyndnsd.rb is installed into the system ruby (no RVM support) and the config.yaml is at /opt/dyndnsd/config.yaml. Modify to your needs.
 
+### Monitoring
+
+For monitoring dyndnsd.rb uses the [metriks](https://github.com/eric/metriks) framework and exposes several metrics like the number of unauthenticated requests, requests that did (not) update a hostname, etc. By default the most important metrics are shown in the [proctitle](https://github.com/eric/metriks#proc-title-reporter) but you can also configure a [Graphite](https://graphiteapp.org/) backend for central monitoring or the [textfile_reporter](https://github.com/prometheus/node_exporter/#textfile-collector) which outputs Graphite-style metrics that are also compatible with Prometheus to a file.
+
+```yaml
+host: "0.0.0.0"
+port: "8245" # the DynDNS.com alternative HTTP port
+db: "/opt/dyndnsd/db.json"
+domain: "dyn.example.org"
+# configure the Graphite backend to be used instead of proctitle
+graphite:
+  host: localhost # defaults for host and port of a carbon server
+  port: 2003
+  prefix: "my.graphite.metrics.naming.structure.dyndnsd"
+# OR configure the textfile reporter instead of Graphite/proctitle
+textfile:
+  file: /path/to/file.prom
+  prefix: "my.graphite.metrics.naming.structure.dyndnsd"
+# configure the updater, here we use command_with_bind_zone, params are updater-specific
+updater:
+  name: "command_with_bind_zone"
+  params:
+    zone_file: "dyn.zone"
+    command: "echo 'Hello'"
+    ttl: "5m"
+    dns: "dns.example.org."
+    email_addr: "admin.example.org."
+# user database with hostnames a user is allowed to update
+users:
+  # 'foo' is username, 'secret' the password
+  foo:
+    password: "secret"
+    hosts:
+      - foo.example.org
+      - bar.example.org
+  test:
+    password: "ihavenohosts"
+```
+
+### Tracing (experimental)
+
+For tracing dyndnsd.rb is instrumented using the [OpenTracing](http://opentracing.io/) framework and will emit span tracing data for the most important operations happening during the request/response cycle. Using a middleware for Rack allows handling incoming OpenTracing span information properly.
+Currently only one OpenTracing-compatible tracer implementation named [CNCF Jaeger](https://github.com/jaegertracing/jaeger) can be configured to use with dyndnsd.rb.
+
+```yaml
+host: "0.0.0.0"
+port: "8245" # the DynDNS.com alternative HTTP port
+db: "/opt/dyndnsd/db.json"
+domain: "dyn.example.org"
+# enable and configure tracing using the (currently only) tracer jaeger
+tracing:
+  trust_incoming_span: false # default value, change to accept incoming OpenTracing spans as parents
+  jaeger:
+    host: 127.0.0.1 # defaults for host and port of local jaeger-agent
+    port: 6831
+    service_name: "my.dyndnsd.identifier"
+# configure the updater, here we use command_with_bind_zone, params are updater-specific
+updater:
+  name: "command_with_bind_zone"
+  params:
+    zone_file: "dyn.zone"
+    command: "echo 'Hello'"
+    ttl: "5m"
+    dns: "dns.example.org."
+    email_addr: "admin.example.org."
+# user database with hostnames a user is allowed to update
+users:
+  # 'foo' is username, 'secret' the password
+  foo:
+    password: "secret"
+    hosts:
+      - foo.example.org
+      - bar.example.org
+  test:
+    password: "ihavenohosts"
+```
+
 ## License
 
 dyndnsd.rb is licensed under the Apache License, Version 2.0. See LICENSE for more information.

Rakefile

@@ -1,6 +1,22 @@
 require 'bundler/gem_tasks'
 require 'rspec/core/rake_task'
+require 'rubocop/rake_task'
+require 'bundler/audit/task'
 
 RSpec::Core::RakeTask.new(:spec)
+RuboCop::RakeTask.new
+Bundler::Audit::Task.new
 
-task :default => :spec
+desc 'Should be run by developer once to prepare initial solargraph usage (fill caches etc.)'
+task :'solargraph:init' do
+  sh 'solargraph download-core'
+end
+
+desc 'Run experimental solargraph type checker'
+task :'solargraph:tc' do
+  sh 'solargraph typecheck'
+end
+
+task default: [:rubocop, :spec, 'bundle:audit']
+
+task travis: [:default, :'solargraph:tc']

dyndnsd.gemspec

@@ -1,5 +1,5 @@
 
-$:.push File.expand_path("../lib", __FILE__)
+$LOAD_PATH.push File.expand_path('lib', __dir__)
 
 require 'dyndnsd/version'
 
@@ -10,22 +10,28 @@ Gem::Specification.new do |s|
   s.description = 'A small, lightweight and extensible DynDNS server written with Ruby and Rack.'
   s.author = 'Christian Nicolai'
   s.email = 'chrnicolai@gmail.com'
-  s.license = 'Apache License Version 2.0'
   s.homepage = 'https://github.com/cmur2/dyndnsd'
+  s.license = 'Apache-2.0'
 
-  s.files = `git ls-files`.split($/)
+  s.files = `git ls-files`.split($INPUT_RECORD_SEPARATOR)
   s.test_files = s.files.grep(%r{^(test|spec|features)/})
-
   s.require_paths = ['lib']
-
   s.executables = ['dyndnsd']
 
-  s.add_runtime_dependency 'rack', '~> 1.6'
-  s.add_runtime_dependency 'json', '~> 1.8'
-  s.add_runtime_dependency 'metriks'
+  s.required_ruby_version = '>= 2.3'
 
-  s.add_development_dependency 'bundler', '~> 1.3'
+  s.add_runtime_dependency 'rack', '~> 2.0'
+  s.add_runtime_dependency 'json'
+  s.add_runtime_dependency 'metriks'
+  s.add_runtime_dependency 'opentracing', '~> 0.5.0'
+  s.add_runtime_dependency 'rack-tracer', '~> 0.9.0'
+  s.add_runtime_dependency 'jaeger-client', '~> 0.10.0'
+
+  s.add_development_dependency 'bundler'
   s.add_development_dependency 'rake'
   s.add_development_dependency 'rspec'
   s.add_development_dependency 'rack-test'
+  s.add_development_dependency 'rubocop', '~> 0.80.0'
+  s.add_development_dependency 'bundler-audit', '~> 0.6.0'
+  s.add_development_dependency 'solargraph'
 end

lib/dyndnsd.rb

@@ -8,172 +8,264 @@ require 'yaml'
 require 'rack'
 require 'metriks'
 require 'metriks/reporter/graphite'
+require 'opentracing'
+require 'rack/tracer'
 
 require 'dyndnsd/generator/bind'
 require 'dyndnsd/updater/command_with_bind_zone'
 require 'dyndnsd/responder/dyndns_style'
 require 'dyndnsd/responder/rest_style'
 require 'dyndnsd/database'
+require 'dyndnsd/helper'
+require 'dyndnsd/textfile_reporter'
 require 'dyndnsd/version'
 
 module Dyndnsd
+  # @return [Logger]
   def self.logger
     @logger
   end
 
+  # @param logger [Logger]
+  # @return [Logger]
   def self.logger=(logger)
     @logger = logger
   end
 
   class LogFormatter
-    def call(lvl, time, progname, msg)
-      "[%s] %-5s %s\n" % [Time.now.strftime('%Y-%m-%d %H:%M:%S'), lvl, msg.to_s]
+    # @param lvl [Object]
+    # @param _time [DateTime]
+    # @param _progname [String]
+    # @param msg [Object]
+    # @return [String]
+    def call(lvl, _time, _progname, msg)
+      format("[%s] %-5s %s\n", Time.now.strftime('%Y-%m-%d %H:%M:%S'), lvl, msg.to_s)
     end
   end
 
   class Daemon
-    def initialize(config, db, updater, responder)
+    # @param config [Hash{String => Object}]
+    # @param db [Dyndnsd::Database]
+    # @param updater [#update]
+    def initialize(config, db, updater)
       @users = config['users']
       @domain = config['domain']
       @db = db
       @updater = updater
-      @responder = responder
 
       @db.load
       @db['serial'] ||= 1
       @db['hosts'] ||= {}
-      (@db.save; update) if @db.changed?
-    end
-
-    def update
+      if @db.changed?
+        @db.save
         @updater.update(@db)
       end
-
-    def is_fqdn_valid?(hostname)
-      return false if hostname.length < @domain.length + 2
-      return false if not hostname.end_with?(@domain)
-      name = hostname.chomp(@domain)
-      return false if not name.match(/^[a-zA-Z0-9_-]+\.$/)
-      true
     end
 
+    # @param username [String]
+    # @param password [String]
+    # @return [Boolean]
+    def authorized?(username, password)
+      Helper.span('check_authorized') do |span|
+        span.set_tag('dyndnsd.user', username)
+
+        allow = Helper.user_allowed?(username, password, @users)
+        if !allow
+          Dyndnsd.logger.warn "Login failed for #{username}"
+          Metriks.meter('requests.auth_failed').mark
+        end
+        allow
+      end
+    end
+
+    # @param env [Hash{String => String}]
+    # @return [Array{Integer,Hash{String => String},Array{String}}]
     def call(env)
-      return @responder.response_for_error(:method_forbidden) if env["REQUEST_METHOD"] != "GET"
-      return @responder.response_for_error(:not_found) if env["PATH_INFO"] != "/nic/update"
+      return [422, {'X-DynDNS-Response' => 'method_forbidden'}, []] if env['REQUEST_METHOD'] != 'GET'
+      return [422, {'X-DynDNS-Response' => 'not_found'}, []] if env['PATH_INFO'] != '/nic/update'
 
-      params = Rack::Utils.parse_query(env["QUERY_STRING"])
-
-      return @responder.response_for_error(:hostname_missing) if not params["hostname"]
-
-      hostnames = params["hostname"].split(',')
-
-      # Check if hostname match rules
-      hostnames.each do |hostname|
-        return @responder.response_for_error(:hostname_malformed) if not is_fqdn_valid?(hostname)
-      end
-
-      user = env["REMOTE_USER"]
-
-      hostnames.each do |hostname|
-        return @responder.response_for_error(:host_forbidden) if not @users[user]['hosts'].include? hostname
-      end
-
-      myip = nil
-
-      if params.has_key?("myip6")
-        # require presence of myip parameter as valid IPAddr (v4) and valid myip6
-        return @responder.response_for_error(:host_forbidden) if not params["myip"]
-        begin
-          IPAddr.new(params["myip"], Socket::AF_INET)
-          IPAddr.new(params["myip6"], Socket::AF_INET6)
-          
-          # myip will be an array
-          myip = [params["myip"], params["myip6"]]
-        rescue ArgumentError
-          return @responder.response_for_error(:host_forbidden)
-        end
-      else
-        # fallback value, always present
-        myip = env["REMOTE_ADDR"]
-
-        # check whether X-Real-IP header has valid IPAddr
-        if env.has_key?("HTTP_X_REAL_IP")
-          begin
-            IPAddr.new(env["HTTP_X_REAL_IP"])
-            myip = env["HTTP_X_REAL_IP"]
-          rescue ArgumentError
-          end
-        end
-
-        # check whether myip parameter has valid IPAddr
-        if params.has_key?("myip")
-          begin
-            IPAddr.new(params["myip"])
-            myip = params["myip"]
-          rescue ArgumentError
-          end
-        end
-      end
-
-      Metriks.meter('requests.valid').mark
-      Dyndnsd.logger.info "Request to update #{hostnames} to #{myip} for user #{user}"
-
-      changes = []
-      hostnames.each do |hostname|
-        if (not @db['hosts'].include? hostname) or (@db['hosts'][hostname] != myip)
-          changes << :good
-          @db['hosts'][hostname] = myip
-          Metriks.meter('requests.good').mark
-        else
-          changes << :nochg
-          Metriks.meter('requests.nochg').mark
-        end
-      end
-
-      if @db.changed?
-        @db['serial'] += 1
-        Dyndnsd.logger.info "Committing update ##{@db['serial']}"
-        @db.save
-        update
-        Metriks.meter('updates.committed').mark
-      end
-
-      @responder.response_for_changes(changes, myip)
+      handle_dyndns_request(env)
     end
 
+    # @return [void]
     def self.run!
       if ARGV.length != 1
-        puts "Usage: dyndnsd config_file"
+        puts 'Usage: dyndnsd config_file'
         exit 1
       end
 
       config_file = ARGV[0]
 
-      if not File.file?(config_file)
-        puts "Config file not found!"
+      if !File.file?(config_file)
+        puts 'Config file not found!'
         exit 1
       end
 
       puts "DynDNSd version #{Dyndnsd::VERSION}"
       puts "Using config file #{config_file}"
 
-      config = YAML::load(File.open(config_file, 'r') { |f| f.read })
+      config = YAML.safe_load(File.open(config_file, 'r', &:read))
 
+      setup_logger(config)
+
+      Dyndnsd.logger.info 'Starting...'
+
+      # drop priviliges as soon as possible
+      # NOTE: first change group than user
+      if config['group']
+        group = Etc.getgrnam(config['group'])
+        Process::Sys.setgid(group.gid) if group
+      end
+      if config['user']
+        user = Etc.getpwnam(config['user'])
+        Process::Sys.setuid(user.uid) if user
+      end
+
+      setup_traps
+
+      setup_monitoring(config)
+
+      setup_tracing(config)
+
+      setup_rack(config)
+    end
+
+    private
+
+    # @param params [Hash{String => String}]
+    # @return [Array{String}]
+    def extract_v4_and_v6_address(params)
+      return [] if !(params['myip'])
+      begin
+        IPAddr.new(params['myip'], Socket::AF_INET)
+        IPAddr.new(params['myip6'], Socket::AF_INET6)
+        [params['myip'], params['myip6']]
+      rescue ArgumentError
+        []
+      end
+    end
+
+    # @param env [Hash{String => String}]
+    # @param params [Hash{String => String}]
+    # @return [Array{String}]
+    def extract_myips(env, params)
+      # require presence of myip parameter as valid IPAddr (v4) and valid myip6
+      return extract_v4_and_v6_address(params) if params.key?('myip6')
+
+      # check whether myip parameter has valid IPAddr
+      return [params['myip']] if params.key?('myip') && Helper.ip_valid?(params['myip'])
+
+      # check whether X-Real-IP header has valid IPAddr
+      return [env['HTTP_X_REAL_IP']] if env.key?('HTTP_X_REAL_IP') && Helper.ip_valid?(env['HTTP_X_REAL_IP'])
+
+      # fallback value, always present
+      [env['REMOTE_ADDR']]
+    end
+
+    # @param hostnames [String]
+    # @param myips [Array{String}]
+    # @return [Array{Symbol}]
+    def process_changes(hostnames, myips)
+      changes = []
+      Helper.span('process_changes') do |span|
+        span.set_tag('dyndnsd.hostnames', hostnames.join(','))
+
+        hostnames.each do |hostname|
+          # myips order is always deterministic
+          if myips.empty? && @db['hosts'].include?(hostname)
+            @db['hosts'].delete(hostname)
+            changes << :good
+            Metriks.meter('requests.good').mark
+          elsif Helper.changed?(hostname, myips, @db['hosts'])
+            @db['hosts'][hostname] = myips
+            changes << :good
+            Metriks.meter('requests.good').mark
+          else
+            changes << :nochg
+            Metriks.meter('requests.nochg').mark
+          end
+        end
+      end
+      changes
+    end
+
+    # @return [void]
+    def update_db
+      @db['serial'] += 1
+      Dyndnsd.logger.info "Committing update ##{@db['serial']}"
+      @db.save
+      @updater.update(@db)
+      Metriks.meter('updates.committed').mark
+    end
+
+    # @param env [Hash{String => String}]
+    # @return [Array{Integer,Hash{String => String},Array{String}}]
+    def handle_dyndns_request(env)
+      params = Rack::Utils.parse_query(env['QUERY_STRING'])
+
+      # require hostname parameter
+      return [422, {'X-DynDNS-Response' => 'hostname_missing'}, []] if !(params['hostname'])
+
+      hostnames = params['hostname'].split(',')
+
+      # check for invalid hostnames
+      invalid_hostnames = hostnames.select { |h| !Helper.fqdn_valid?(h, @domain) }
+      return [422, {'X-DynDNS-Response' => 'hostname_malformed'}, []] if invalid_hostnames.any?
+
+      user = env['REMOTE_USER']
+
+      # check for hostnames that the user does not own
+      forbidden_hostnames = hostnames - @users[user]['hosts']
+      return [422, {'X-DynDNS-Response' => 'host_forbidden'}, []] if forbidden_hostnames.any?
+
+      if params['offline'] == 'YES'
+        myips = []
+      else
+        myips = extract_myips(env, params)
+        # require at least one IP to update
+        return [422, {'X-DynDNS-Response' => 'host_forbidden'}, []] if myips.empty?
+      end
+
+      Metriks.meter('requests.valid').mark
+      Dyndnsd.logger.info "Request to update #{hostnames} to #{myips} for user #{user}"
+
+      changes = process_changes(hostnames, myips)
+
+      update_db if @db.changed?
+
+      [200, {'X-DynDNS-Response' => 'success'}, [changes, myips]]
+    end
+
+    # SETUP
+
+    # @param config [Hash{String => Object}]
+    # @return [void]
+    private_class_method def self.setup_logger(config)
       if config['logfile']
         Dyndnsd.logger = Logger.new(config['logfile'])
       else
         Dyndnsd.logger = Logger.new(STDOUT)
       end
 
-      Dyndnsd.logger.progname = "dyndnsd"
+      Dyndnsd.logger.progname = 'dyndnsd'
       Dyndnsd.logger.formatter = LogFormatter.new
+    end
 
-      Dyndnsd.logger.info "Starting..."
-
-      # drop privs (first change group than user)
-      Process::Sys.setgid(Etc.getgrnam(config['group']).gid) if config['group']
-      Process::Sys.setuid(Etc.getpwnam(config['user']).uid) if config['user']
+    # @return [void]
+    private_class_method def self.setup_traps
+      Signal.trap('INT') do
+        Dyndnsd.logger.info 'Quitting...'
+        Rack::Handler::WEBrick.shutdown
+      end
+      Signal.trap('TERM') do
+        Dyndnsd.logger.info 'Quitting...'
+        Rack::Handler::WEBrick.shutdown
+      end
+    end
 
+    # @param config [Hash{String => Object}]
+    # @return [void]
+    private_class_method def self.setup_monitoring(config)
       # configure metriks
       if config['graphite']
         host = config['graphite']['host'] || 'localhost'
@@ -182,6 +274,12 @@ module Dyndnsd
         options[:prefix] = config['graphite']['prefix'] if config['graphite']['prefix']
         reporter = Metriks::Reporter::Graphite.new(host, port, options)
         reporter.start
+      elsif config['textfile']
+        file = config['textfile']['file'] || '/tmp/dyndnsd-metrics.prom'
+        options = {}
+        options[:prefix] = config['textfile']['prefix'] if config['textfile']['prefix']
+        reporter = Dyndnsd::TextfileReporter.new(file, options)
+        reporter.start
       else
         reporter = Metriks::Reporter::ProcTitle.new
         reporter.add 'good', 'sec' do
@@ -192,33 +290,45 @@ module Dyndnsd
         end
         reporter.start
       end
+    end
 
+    # @param config [Hash{String => Object}]
+    # @return [void]
+    private_class_method def self.setup_tracing(config)
+      # configure OpenTracing
+      if config.dig('tracing', 'jaeger')
+        require 'jaeger/client'
+
+        host = config['tracing']['jaeger']['host'] || '127.0.0.1'
+        port = config['tracing']['jaeger']['port'] || 6831
+        service_name = config['tracing']['jaeger']['service_name'] || 'dyndnsd'
+        OpenTracing.global_tracer = Jaeger::Client.build(
+          host: host, port: port, service_name: service_name, flush_interval: 1
+        )
+      end
+    end
+
+    # @param config [Hash{String => Object}]
+    # @return [void]
+    private_class_method def self.setup_rack(config)
       # configure daemon
       db = Database.new(config['db'])
-      updater = Updater::CommandWithBindZone.new(config['domain'], config['updater']['params']) if config['updater']['name'] == 'command_with_bind_zone'
-      responder = Responder::DynDNSStyle.new
+      updater = Updater::CommandWithBindZone.new(config['domain'], config.dig('updater', 'params')) if config.dig('updater', 'name') == 'command_with_bind_zone'
+      daemon = Daemon.new(config, db, updater)
 
       # configure rack
-      app = Daemon.new(config, db, updater, responder)
-      app = Rack::Auth::Basic.new(app, "DynDNS") do |user,pass|
-        allow = (config['users'].has_key? user) and (config['users'][user]['password'] == pass)
-        if not allow
-          Dyndnsd.logger.warn "Login failed for #{user}"
-          Metriks.meter('requests.auth_failed').mark
-        end
-        allow
+      app = Rack::Auth::Basic.new(daemon, 'DynDNS', &daemon.method(:authorized?))
+
+      if config['responder'] == 'RestStyle'
+        app = Responder::RestStyle.new(app)
+      else
+        app = Responder::DynDNSStyle.new(app)
       end
 
-      Signal.trap('INT') do
-        Dyndnsd.logger.info "Quitting..."
-        Rack::Handler::WEBrick.shutdown
-      end
-      Signal.trap('TERM') do
-        Dyndnsd.logger.info "Quitting..."
-        Rack::Handler::WEBrick.shutdown
-      end
+      trust_incoming_span = config.dig('tracing', 'trust_incoming_span') || false
+      app = Rack::Tracer.new(app, trust_incoming_span: trust_incoming_span)
 
-      Rack::Handler::WEBrick.run app, :Host => config['host'], :Port => config['port']
+      Rack::Handler::WEBrick.run app, Host: config['host'], Port: config['port']
     end
   end
 end

lib/dyndnsd/database.rb

@@ -7,24 +7,30 @@ module Dyndnsd
 
     def_delegators :@db, :[], :[]=, :each, :has_key?
 
+    # @param db_file [String]
     def initialize(db_file)
       @db_file = db_file
     end
 
+    # @return [void]
     def load
       if File.file?(@db_file)
-        @db = JSON.load(File.open(@db_file, 'r') { |f| f.read })
+        @db = JSON.parse(File.read(@db_file, mode: 'r'))
       else
         @db = {}
       end
       @db_hash = @db.hash
     end
 
+    # @return [void]
     def save
+      Helper.span('database_save') do |_span|
         File.open(@db_file, 'w') { |f| JSON.dump(@db, f) }
         @db_hash = @db.hash
       end
+    end
 
+    # @return [Boolean]
     def changed?
       @db_hash != @db.hash
     end

lib/dyndnsd/generator/bind.rb

@@ -2,6 +2,8 @@
 module Dyndnsd
   module Generator
     class Bind
+      # @param domain [String]
+      # @param config [Hash{String => Object}]
       def initialize(domain, config)
         @domain = domain
         @ttl = config['ttl']
@@ -10,25 +12,27 @@ module Dyndnsd
         @additional_zone_content = config['additional_zone_content']
       end
 
-      def generate(zone)
+      # @param db [Dyndnsd::Database]
+      # @return [String]
+      def generate(db)
         out = []
         out << "$TTL #{@ttl}"
         out << "$ORIGIN #{@domain}."
-        out << ""
-        out << "@ IN SOA #{@dns} #{@email_addr} ( #{zone['serial']} 3h 5m 1w 1h )"
+        out << ''
+        out << "@ IN SOA #{@dns} #{@email_addr} ( #{db['serial']} 3h 5m 1w 1h )"
         out << "@ IN NS #{@dns}"
-        out << ""
-        zone['hosts'].each do |hostname,ips|
-          (ips.is_a?(Array) ? ips : [ips]).each do |ip|
+        out << ''
+        db['hosts'].each do |hostname, ips|
+          ips.each do |ip|
             ip = IPAddr.new(ip).native
-            type = ip.ipv6? ? "AAAA" : "A"
+            type = ip.ipv6? ? 'AAAA' : 'A'
             name = hostname.chomp('.' + @domain)
             out << "#{name} IN #{type} #{ip}"
           end
         end
-        out << ""
+        out << ''
         out << @additional_zone_content
-        out << ""
+        out << ''
         out.join("\n")
       end
     end

lib/dyndnsd/helper.rb

@@ -0,0 +1,68 @@
+
+require 'ipaddr'
+
+module Dyndnsd
+  class Helper
+    # @param hostname [String]
+    # @param domain [String]
+    # @return [Boolean]
+    def self.fqdn_valid?(hostname, domain)
+      return false if hostname.length < domain.length + 2
+      return false if !hostname.end_with?(domain)
+      name = hostname.chomp(domain)
+      return false if !name.match(/^[a-zA-Z0-9_-]+\.$/)
+      true
+    end
+
+    # @param ip [String]
+    # @return [Boolean]
+    def self.ip_valid?(ip)
+      IPAddr.new(ip)
+      true
+    rescue ArgumentError
+      false
+    end
+
+    # @param username [String]
+    # @param password [String]
+    # @param users [Hash]
+    # @return [Boolean]
+    def self.user_allowed?(username, password, users)
+      (users.key? username) && (users[username]['password'] == password)
+    end
+
+    # @param hostname [String]
+    # @param myips [Array]
+    # @param hosts [Hash]
+    # @return [Boolean]
+    def self.changed?(hostname, myips, hosts)
+      # myips order is always deterministic
+      ((!hosts.include? hostname) || (hosts[hostname] != myips)) && !myips.empty?
+    end
+
+    # @param operation [String]
+    # @param block [Proc]
+    # @return [void]
+    def self.span(operation, &block)
+      scope = OpenTracing.start_active_span(operation)
+      span = scope.span
+      span.set_tag('component', 'dyndnsd')
+      span.set_tag('span.kind', 'server')
+      begin
+        block.call(span)
+      rescue StandardError => e
+        span.set_tag('error', true)
+        span.log_kv(
+          event: 'error',
+          'error.kind': e.class.to_s,
+          'error.object': e,
+          message: e.message,
+          stack: e.backtrace&.join("\n") || ''
+        )
+        raise
+      ensure
+        scope.close
+      end
+    end
+  end
+end

lib/dyndnsd/responder/dyndns_style.rb

@@ -2,19 +2,67 @@
 module Dyndnsd
   module Responder
     class DynDNSStyle
-      def response_for_error(state)
-        # general http errors
-        return [405, {"Content-Type" => "text/plain"}, ["Method Not Allowed"]] if state == :method_forbidden
-        return [404, {"Content-Type" => "text/plain"}, ["Not Found"]] if state == :not_found
-        # specific errors
-        return [200, {"Content-Type" => "text/plain"}, ["notfqdn"]] if state == :hostname_missing
-        return [200, {"Content-Type" => "text/plain"}, ["nohost"]] if state == :host_forbidden
-        return [200, {"Content-Type" => "text/plain"}, ["notfqdn"]] if state == :hostname_malformed
+      # @param app [#call]
+      def initialize(app)
+        @app = app
       end
 
-      def response_for_changes(states, ip)
-        body = states.map { |state| "#{state} #{ip.is_a?(Array) ? ip.join(' ') : ip}" }.join("\n")
-        return [200, {"Content-Type" => "text/plain"}, [body]]
+      # @param env [Hash{String => String}]
+      # @return [Array{Integer,Hash{String => String},Array{String}}]
+      def call(env)
+        @app.call(env).tap do |status_code, headers, body|
+          if headers.key?('X-DynDNS-Response')
+            return decorate_dyndnsd_response(status_code, headers, body)
+          else
+            return decorate_other_response(status_code, headers, body)
+          end
+        end
+      end
+
+      private
+
+      # @param status_code [Integer]
+      # @param headers [Hash{String => String}]
+      # @param body [Array{String}]
+      # @return [Array{Integer,Hash{String => String},Array{String}}]
+      def decorate_dyndnsd_response(status_code, headers, body)
+        if status_code == 200
+          [200, {'Content-Type' => 'text/plain'}, [get_success_body(body[0], body[1])]]
+        elsif status_code == 422
+          error_response_map[headers['X-DynDNS-Response']]
+        end
+      end
+
+      # @param status_code [Integer]
+      # @param headers [Hash{String => String}]
+      # @param _body [Array{String}]
+      # @return [Array{Integer,Hash{String => String},Array{String}}]
+      def decorate_other_response(status_code, headers, _body)
+        if status_code == 400
+          [status_code, headers, ['Bad Request']]
+        elsif status_code == 401
+          [status_code, headers, ['badauth']]
+        end
+      end
+
+      # @param changes [Array{Symbol}]
+      # @param myips [Array{String}]
+      # @return [String]
+      def get_success_body(changes, myips)
+        changes.map { |change| "#{change} #{myips.join(' ')}" }.join("\n")
+      end
+
+      # @return [Hash{String => Object}]
+      def error_response_map
+        {
+          # general http errors
+          'method_forbidden'   => [405, {'Content-Type' => 'text/plain'}, ['Method Not Allowed']],
+          'not_found'          => [404, {'Content-Type' => 'text/plain'}, ['Not Found']],
+          # specific errors
+          'hostname_missing'   => [200, {'Content-Type' => 'text/plain'}, ['notfqdn']],
+          'hostname_malformed' => [200, {'Content-Type' => 'text/plain'}, ['notfqdn']],
+          'host_forbidden'     => [200, {'Content-Type' => 'text/plain'}, ['nohost']]
+        }
       end
     end
   end

lib/dyndnsd/responder/rest_style.rb

@@ -2,19 +2,67 @@
 module Dyndnsd
   module Responder
     class RestStyle
-      def response_for_error(state)
-        # general http errors
-        return [405, {"Content-Type" => "text/plain"}, ["Method Not Allowed"]] if state == :method_forbidden
-        return [404, {"Content-Type" => "text/plain"}, ["Not Found"]] if state == :not_found
-        # specific errors
-        return [422, {"Content-Type" => "text/plain"}, ["Hostname missing"]] if state == :hostname_missing
-        return [403, {"Content-Type" => "text/plain"}, ["Forbidden"]] if state == :host_forbidden
-        return [422, {"Content-Type" => "text/plain"}, ["Hostname malformed"]] if state == :hostname_malformed
+      # @param app [#call]
+      def initialize(app)
+        @app = app
       end
 
-      def response_for_changes(states, ip)
-        body = states.map { |state| state == :good ? "Changed to #{ip.is_a?(Array) ? ip.join(' ') : ip}" : "No change needed for #{ip.is_a?(Array) ? ip.join(' ') : ip}" }.join("\n")
-        return [200, {"Content-Type" => "text/plain"}, [body]]
+      # @param env [Hash{String => String}]
+      # @return [Array{Integer,Hash{String => String},Array{String}}]
+      def call(env)
+        @app.call(env).tap do |status_code, headers, body|
+          if headers.key?('X-DynDNS-Response')
+            return decorate_dyndnsd_response(status_code, headers, body)
+          else
+            return decorate_other_response(status_code, headers, body)
+          end
+        end
+      end
+
+      private
+
+      # @param status_code [Integer]
+      # @param headers [Hash{String => String}]
+      # @param body [Array{String}]
+      # @return [Array{Integer,Hash{String => String},Array{String}}]
+      def decorate_dyndnsd_response(status_code, headers, body)
+        if status_code == 200
+          [200, {'Content-Type' => 'text/plain'}, [get_success_body(body[0], body[1])]]
+        elsif status_code == 422
+          error_response_map[headers['X-DynDNS-Response']]
+        end
+      end
+
+      # @param status_code [Integer]
+      # @param headers [Hash{String => String}]
+      # @param _body [Array{String}]
+      # @return [Array{Integer,Hash{String => String},Array{String}}]
+      def decorate_other_response(status_code, headers, _body)
+        if status_code == 400
+          [status_code, headers, ['Bad Request']]
+        elsif status_code == 401
+          [status_code, headers, ['Unauthorized']]
+        end
+      end
+
+      # @param changes [Array{Symbol}]
+      # @param myips [Array{String}]
+      # @return [String]
+      def get_success_body(changes, myips)
+        changes.map { |change| change == :good ? "Changed to #{myips.join(' ')}" : "No change needed for #{myips.join(' ')}" }.join("\n")
+      end
+
+      # @return [Hash{String => Object}]
+      def error_response_map
+        {
+          # general http errors
+          'method_forbidden'   => [405, {'Content-Type' => 'text/plain'}, ['Method Not Allowed']],
+          'not_found'          => [404, {'Content-Type' => 'text/plain'}, ['Not Found']],
+          # specific errors
+          'hostname_missing'   => [422, {'Content-Type' => 'text/plain'}, ['Hostname missing']],
+          'hostname_malformed' => [422, {'Content-Type' => 'text/plain'}, ['Hostname malformed']],
+          'host_forbidden'     => [403, {'Content-Type' => 'text/plain'}, ['Forbidden']]
+        }
       end
     end
   end

lib/dyndnsd/textfile_reporter.rb

@@ -0,0 +1,123 @@
+
+# Adapted from https://github.com/eric/metriks-graphite/blob/master/lib/metriks/reporter/graphite.rb
+
+require 'metriks'
+
+module Dyndnsd
+  class TextfileReporter
+    # @return [String]
+    attr_reader :file
+
+    # @param file [String]
+    # @param options [Hash{Symbol => Object}]
+    def initialize(file, options = {})
+      @file = file
+
+      @prefix = options[:prefix]
+
+      @registry  = options[:registry] || Metriks::Registry.default
+      @interval  = options[:interval] || 60
+      @on_error  = options[:on_error] || proc { |ex| }
+    end
+
+    # @return [void]
+    def start
+      @thread ||= Thread.new do
+        loop do
+          sleep @interval
+
+          Thread.new do
+            begin
+              write
+            rescue StandardError => e
+              @on_error[e] rescue nil
+            end
+          end
+        end
+      end
+    end
+
+    # @return [void]
+    def stop
+      @thread&.kill
+      @thread = nil
+    end
+
+    # @return [void]
+    def restart
+      stop
+      start
+    end
+
+    # @return [void]
+    def write
+      File.open(@file, 'w') do |f|
+        @registry.each do |name, metric|
+          case metric
+          when Metriks::Meter
+            write_metric f, name, metric, [
+              :count, :one_minute_rate, :five_minute_rate,
+              :fifteen_minute_rate, :mean_rate
+            ]
+          when Metriks::Counter
+            write_metric f, name, metric, [
+              :count
+            ]
+          when Metriks::UtilizationTimer
+            write_metric f, name, metric, [
+              :count, :one_minute_rate, :five_minute_rate,
+              :fifteen_minute_rate, :mean_rate,
+              :min, :max, :mean, :stddev,
+              :one_minute_utilization, :five_minute_utilization,
+              :fifteen_minute_utilization, :mean_utilization
+            ], [
+              :median, :get_95th_percentile
+            ]
+          when Metriks::Timer
+            write_metric f, name, metric, [
+              :count, :one_minute_rate, :five_minute_rate,
+              :fifteen_minute_rate, :mean_rate,
+              :min, :max, :mean, :stddev
+            ], [
+              :median, :get_95th_percentile
+            ]
+          when Metriks::Histogram
+            write_metric f, name, metric, [
+              :count, :min, :max, :mean, :stddev
+            ], [
+              :median, :get_95th_percentile
+            ]
+          end
+        end
+      end
+    end
+
+    # @param file [String]
+    # @param base_name [String]
+    # @param metric [Object]
+    # @param keys [Array{Symbol}]
+    # @param snapshot_keys [Array{Symbol}]
+    # @return [void]
+    def write_metric(file, base_name, metric, keys, snapshot_keys = [])
+      time = Time.now.to_i
+
+      base_name = base_name.to_s.gsub(/ +/, '_')
+      base_name = "#{@prefix}.#{base_name}" if @prefix
+
+      keys.flatten.each do |key|
+        name = key.to_s.gsub(/^get_/, '')
+        value = metric.send(key)
+        file.write("#{base_name}.#{name} #{value} #{time}\n")
+      end
+
+      unless snapshot_keys.empty?
+        snapshot = metric.snapshot
+        snapshot_keys.flatten.each do |key|
+          name = key.to_s.gsub(/^get_/, '')
+          value = snapshot.send(key)
+          file.write("#{base_name}.#{name} #{value} #{time}\n")
+        end
+      end
+    end
+  end
+end

lib/dyndnsd/updater/command_with_bind_zone.rb

@@ -2,21 +2,30 @@
 module Dyndnsd
   module Updater
     class CommandWithBindZone
+      # @param domain [String]
+      # @param config [Hash{String => Object}]
       def initialize(domain, config)
         @zone_file = config['zone_file']
         @command = config['command']
         @generator = Generator::Bind.new(domain, config)
       end
 
-      def update(zone)
+      # @param db [Dyndnsd::Database]
+      # @return [void]
+      def update(db)
+        Helper.span('updater_update') do |span|
+          span.set_tag('dyndnsd.updater.name', self.class.name&.split('::')&.last || 'None')
+
           # write zone file in bind syntax
-        File.open(@zone_file, 'w') { |f| f.write(@generator.generate(zone)) }
+          File.open(@zone_file, 'w') { |f| f.write(@generator.generate(db)) }
           # call user-defined command
           pid = fork do
             exec @command
           end
+
           # detach so children don't become zombies
-        Process.detach(pid)
+          Process.detach(pid) if pid
+        end
       end
     end
   end

lib/dyndnsd/version.rb

@@ -1,4 +1,4 @@
 
 module Dyndnsd
-  VERSION = "1.6.0"
+  VERSION = '2.1.1'.freeze
 end

spec/daemon_spec.rb

@@ -18,20 +18,25 @@ describe Dyndnsd::Daemon do
     }
     db = Dyndnsd::DummyDatabase.new({})
     updater = Dyndnsd::Updater::Dummy.new
-    responder = Dyndnsd::Responder::DynDNSStyle.new
-    app = Dyndnsd::Daemon.new(config, db, updater, responder)
+    daemon = Dyndnsd::Daemon.new(config, db, updater)
 
-    Rack::Auth::Basic.new(app, "DynDNS") do |user,pass|
-      (config['users'].has_key? user) and (config['users'][user]['password'] == pass)
-    end
+    app = Rack::Auth::Basic.new(daemon, 'DynDNS', &daemon.method(:authorized?))
+
+    app = Dyndnsd::Responder::DynDNSStyle.new(app)
+
+    Rack::Tracer.new(app, trust_incoming_span: false)
   end
 
   it 'requires authentication' do
     get '/'
     expect(last_response.status).to eq(401)
+    expect(last_response.body).to eq('badauth')
+  end
 
-    pending 'Need to find a way to add custom body on 401 responses'
-    expect(last_response).not_to be_ok
+  it 'requires configured correct credentials' do
+    authorize 'test', 'wrongsecret'
+    get '/'
+    expect(last_response.status).to eq(401)
     expect(last_response.body).to eq('badauth')
   end
 
@@ -96,6 +101,7 @@ describe Dyndnsd::Daemon do
 
   it 'rejects request if user does not own one hostname' do
     authorize 'test', 'secret'
+
     get '/nic/update?hostname=notmyhost.example.org'
     expect(last_response).to be_ok
     expect(last_response.body).to eq('nohost')
@@ -161,6 +167,34 @@ describe Dyndnsd::Daemon do
     expect(last_response.body).to eq("nochg 2001:db8::1\ngood 2001:db8::1")
   end
 
+  it 'offlines a host' do
+    authorize 'test', 'secret'
+
+    get '/nic/update?hostname=foo.example.org&myip=1.2.3.4'
+    expect(last_response).to be_ok
+    expect(last_response.body).to eq('good 1.2.3.4')
+
+    get '/nic/update?hostname=foo.example.org&offline=YES'
+    expect(last_response).to be_ok
+    expect(last_response.body).to eq('good ')
+
+    get '/nic/update?hostname=foo.example.org&offline=YES'
+    expect(last_response).to be_ok
+    expect(last_response.body).to eq('nochg ')
+
+    get '/nic/update?hostname=foo.example.org&myip=1.2.3.4'
+    expect(last_response).to be_ok
+    expect(last_response.body).to eq('good 1.2.3.4')
+
+    get '/nic/update?hostname=foo.example.org&myip=1.2.3.4&offline=YES'
+    expect(last_response).to be_ok
+    expect(last_response.body).to eq('good ')
+
+    get '/nic/update?hostname=foo.example.org&myip=1.2.3.4&offline=YES'
+    expect(last_response).to be_ok
+    expect(last_response.body).to eq('nochg ')
+  end
+
   it 'uses clients remote IP address if myip not specified' do
     authorize 'test', 'secret'
     get '/nic/update?hostname=foo.example.org'
@@ -185,7 +219,7 @@ describe Dyndnsd::Daemon do
 
     get '/nic/update?hostname=foo.example.org&myip=1.2.3.4&myip6=2001:db8::1'
     expect(last_response).to be_ok
-    expect(last_response.body).to eq("good 1.2.3.4 2001:db8::1")
+    expect(last_response.body).to eq('good 1.2.3.4 2001:db8::1')
 
     get '/nic/update?hostname=foo.example.org&myip=BROKENIP&myip6=2001:db8::1'
     expect(last_response).to be_ok

spec/support/dummy_database.rb

@@ -25,5 +25,3 @@ module Dyndnsd
     end
   end
 end
-
-