Initial Commit

cloudflare_dyndns_update.rb

@@ -0,0 +1,330 @@
+#!/usr/bin/env ruby
+
+# -----
+#
+# Copyright (c) 2024 mahesh
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+# of the Software, and to permit persons to whom the Software is furnished to do
+# so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+#
+# -----
+
+require 'pp'
+require 'optparse'
+require 'net/http'
+require 'uri'
+require 'json'
+require 'yaml'
+require 'logger'
+
+# ------------------
+# Helper Classes
+# ------------------
+class CloudflareDynDNSUpdater
+  attr_accessor :options, :myip, :config, :cache
+
+  def initialize(options)
+    @logger = Logger.new(STDOUT)
+    @options = options
+    @config = read_config_file
+    @logger.level = @options[:debug] ? Logger::DEBUG : Logger::INFO
+    @logger.info($0) { "Starting..." }
+    @query_info = Hash.new
+    @cache_updated = false
+    if @options[:api_key].empty?
+      @logger.error "Need Cloudflare API key to proceed"
+      exit 1
+    end
+  end
+
+  def run()
+    #
+    # Load the cache so we know hosts and their IPs were updated
+    # in the past
+    #
+    @cache = read_cache_file
+    @logger.debug @cache.inspect
+
+    #
+    # Get the Public IP (WAN). We will compare this with the IP
+    # in the cache to know if the IP has changed and needs to be
+    # updated in Cloudflare's DNS
+    #
+    @myip = get_public_ip
+    @logger.info "Public IP: #{@myip}"
+
+    #
+    # Query DNS records
+    #
+    process_dns
+
+    # Write updated cache
+    if @cache_updated
+      write_cache_file
+    end
+  end
+
+  def report()
+    @logger.info($0) { "Done." }
+  end
+
+  private
+
+  #
+  # Read configuration file, which contains the list of hosts and
+  # their credentials. Configuration file uses the YAML format
+  # and has the following template:
+  #
+  # -----------
+  # hosts:
+  # - host: hostone.com
+  #   zone_id: <cloudflare hostone zone_id>
+  # - host: hosttwo.com
+  #   zone_id: <cloudflare hosttwo zone_id>
+  # - ...
+  # -----------
+  #
+  # Default location of the configuration file is:
+  #
+  #   ~/.cfdyndns.yaml
+  #
+  # Alternate location may be provided with [-f|--config_file] option
+  #
+  def read_config_file()
+    if File.exists?(options[:config_file])
+      return YAML.load_file(options[:config_file])
+    else
+      @logger.error "Config file [#{options[:config_file]}] missing!"
+    end
+  end
+
+  #
+  # To avoid frequent queries to Cloudflare, store the status of
+  # latest update to a cache file. Cloudflare is updated only if
+  # our public IP has changed.
+  #
+  # Default location of cache file is:
+  #
+  #   ~/.cfdyndns.cache
+  #
+  # Alternate location may be provided with [-c|--cache_file] option
+  #
+  def read_cache_file()
+    #
+    # Update to Cloudflare may be forced by forgetting cached
+    # values. This is controlled by the [-u|--force_update] option
+    #
+    if options[:force_update]
+      if File.exists?(options[:cache_file])
+        File.delete(options[:cache_file])
+      end
+    end
+
+    #
+    # Load the cache file
+    #
+    return File.exists?(options[:cache_file]) ? YAML.load_file(options[:cache_file]) : {}
+  end
+
+  #
+  # Store IPs from current update into cache
+  #
+  def write_cache_file()
+    @logger.debug @cache.inspect
+    @logger.info "Writing updated cache file"
+    File.open(options[:cache_file], "w") {|f| f.write(@cache.to_yaml)}
+  end
+
+  #
+  # Acquire the public IP from an external service
+  #
+  def get_public_ip()
+    return Net::HTTP.get(URI('http://ipinfo.io/ip'))
+  end
+
+  #
+  # Query Cloudflare for Domains info
+  #
+  def process_dns()
+    #
+    # Handle each host in the config file at a time
+    #
+    @config['hosts'].each {|h|
+      if @cache[h['host']] && @myip.eql?(@cache[h['host']]['ip'])
+        @logger.info "Skipping #{h['host']} - Already pointing to #{@myip}"
+      else
+        query_sts_good = query_dns(h)
+
+        if query_sts_good
+            update_sts_good = update_dns(h['host'])
+        end
+      end
+    }
+  end
+
+  def query_dns(host)
+      sts_good = false
+      url = "https://api.cloudflare.com/client/v4/zones/#{host['zone_id']}/dns_records"
+
+      @logger.debug "Querying Cloudflare for host [#{host['host']}] - #{url}"
+      uri = URI(url)
+
+      Net::HTTP.start(uri.host, uri.port, :use_ssl => true) do |http|
+        request = Net::HTTP::Get.new uri
+        request.add_field 'Content-Type', 'application/json'
+        request.add_field 'Authorization', "Bearer #{@options[:api_key]}"
+        request.add_field 'User-Agent', "#{@options[:user_agent]}"
+        response = http.request request # Net::HTTPResponse object
+        sts_good = handle_query(JSON.parse(response.body))
+      end
+      return sts_good
+  end
+
+  def handle_query(body)
+    if body['success']
+      body['result'].each {|entry|
+        if entry['type'].eql?('A')
+          @query_info[entry['name']] = entry
+          return true
+        end
+      }
+      return false
+    else
+      body['errors'].each {|err|
+        @logger.error "Error status returned #{err['code']}: #{err['message']}"
+      }
+      return false
+    end
+  end
+
+  #
+  # Update Cloudflare if IP has changed
+  #
+  def update_dns(host)
+    sts_good = false
+
+    #
+    # Handle each host in the config file at a time
+    #
+    if @query_info.has_key?(host)
+      # Use information from query response when possible
+      q_info = @query_info[host]
+
+      url = "https://api.cloudflare.com/client/v4/zones/#{q_info['zone_id']}/dns_records/#{q_info['id']}"
+      @logger.debug "Updating Cloudflare for host [#{host['host']}] - #{url}"
+
+      uri = URI(url)
+      request_body = {
+        'type' => q_info['type'],
+        'name' => q_info['name'],
+        'content' => @myip
+      }
+
+      @logger.debug request_body.to_json
+
+      Net::HTTP.start(uri.host, uri.port, :use_ssl => true) do |http|
+        request = Net::HTTP::Patch.new uri
+        request.add_field 'Content-Type', 'application/json'
+        request.add_field 'Authorization', "Bearer #{@options[:api_key]}"
+        request.add_field 'User-Agent', "#{@options[:user_agent]}"
+        request.body = request_body.to_json
+        response = http.request request # Net::HTTPResponse object
+        sts_good = handle_update(JSON.parse(response.body))
+      end
+      return sts_good
+
+    else
+      @logger.error "Did not find query information for host #{host}"
+    end
+    return sts_good
+  end
+
+  def handle_update(body)
+    if body['success']
+      entry = body['result']
+      @logger.info "Successfully updated DNS entry type #{entry['type']} - #{entry['name']} - #{entry['content']}"
+      @cache[entry['name']] = {'ip' => entry['content']}
+      @cache_updated = true
+      return true
+    else
+      body['errors'].each {|err|
+        @logger.error "Error status returned #{err['code']}: #{err['message']}"
+      }
+      return false
+    end
+  end
+end
+
+# -------------------
+# Options parsing
+# -------------------
+#
+# Default values of command line options
+#
+options = {
+  :config_file => "#{Dir.home}/.cfdyndns.yaml",
+  :cache_file => "#{Dir.home}/.cfdyndns.cache",
+  :user_agent => 'HeshApps Cloudflare Dynamic DNS Updater v1.0',
+  :force_update => false,
+  :debug => false,
+  :api_key => ''
+}
+
+#
+# Get command line options
+#
+op = OptionParser.new do |opts|
+  opts.banner = "Usage: cloudflare_dyndns_update.rb [options]"
+
+  opts.on("-d", "--debug", "Enable debug messages") do |debug|
+    options[:debug] = debug
+  end
+  opts.on("-u", "--force_update", "Force DNS update") do |force_update|
+    options[:force_update] = force_update
+  end
+  opts.on("-f", "--config_file FILE", "Location of configuration file") do |file|
+    options[:config_file] = file
+  end
+  opts.on("-c", "--cache_file FILE", "Location of cache file") do |file|
+    options[:cache_file] = file
+  end
+  opts.on("-k", "--api_key KEY", "Cloudflare API authorization key") do |key|
+    options[:api_key] = key
+  end
+  opts.on("-h", "--help", "Display this help") do |help|
+    options[:help] = help
+  end
+end
+
+op.parse!
+
+if options[:help]
+  puts op.help
+  exit
+end
+
+# ------------------
+# Execution part
+# ------------------
+updater = CloudflareDynDNSUpdater.new(options)
+updater.run
+updater.report
+
+#
+# Mahesh Asolkar, 2024
+# vim: ai ts=2 sts=2 et sw=2 filetype=ruby