dynamicdns: Replace ez-ipupdate

Add Python implementation of GnuDIP client.

Tests:

- In testing container, configure Dynamic DNS with a (previously
  offlined) freedombox.rocks account. FreedomBox interface shows that
  the address has been updated. GnuDIP server also shows the correct
  IP address.

- Running "gnudip update" and "dynamicdns update" actions produce the
  expected results.

actions/dynamicdns

@@ -31,7 +31,7 @@ UPDATEMINUTES=5
 # a "blind" update
 UPDATEMINUTESUNKNOWN=3600
 TOOLNAME=ez-ipupdate
-UPDATE_TOOL=$(which ${TOOLNAME})
+GNUDIP_ACTION=/usr/share/plinth/actions/gnudip
 DISABLED_STRING='disabled'
 ENABLED_STRING='enabled'
 
@@ -157,13 +157,6 @@ doWriteCFG()
         else
             # we are directly connected
             echo "NAT no" >> ${HELPERCFG}
-            # if this file is added ez-ipupdate will take ip form this interface
-            {
-                echo "interface=${default_interface}"
-                # if this line is added to config file, ez-ipupdate will be launched on startup via init.d
-                echo "daemon"
-                echo "execute=${0} success"
-            } >> ${out_file}
         fi
     fi
 }
@@ -296,7 +289,7 @@ doGetWANIP()
     fi
 }
 
-# actualy do the update (using wget or ez-ipupdate or even both)
+# actualy do the update (using wget or gnudip action or even both)
 # this function is called via cronjob
 doUpdate()
 {
@@ -309,7 +302,11 @@ doUpdate()
         return
     fi
     if [ ! -z "${server}" ];then
-        start-stop-daemon -S -x "${UPDATE_TOOL}" -m -p "${PIDFILE}" -- -c "${cfgfile}"
+        if "${GNUDIP_ACTION}" update; then
+            ${0} success ${wanip}
+        else
+            ${0} failed
+        fi
     fi
     if [ ! -z "${updateurl}" ];then
         doReplaceVars
@@ -351,24 +348,14 @@ case ${cmd} in
     ;;
     start)
         doGetWANIP
-        if [ "$(grep ^NAT ${HELPERCFG} | awk '{print $2}')" = "no" ];then
-            #if we are not behind a NAT device and we use gnudip, start the daemon tool
-            gnudipServer=$(grep ^server= ${cfgfile} 2> /dev/null | cut -d = -f 2- |grep -v ^\'\')
-            if [ ! -f ${CFG} -a ! -z "${gnudipServer}" ];then
-                mv ${CFG_disabled} ${CFG}
-                /etc/init.d/${TOOLNAME} start
-            fi
-            # if we are not behind a NAT device and we use update-URL, add a cronjob
-            # (daemon tool does not support update-URL feature)
-            if [ ! -z "$(grep ^POSTURL $HELPERCFG | awk '{print $2}')" ];then
-                echo "*/${UPDATEMINUTES} * * * * root ${0} update" > ${CRONJOB}
-                $0 update
-            fi
-        else
-            # if we are behind a NAT device, add a cronjob (daemon tool cannot monitor WAN IP changes)
-            echo "*/${UPDATEMINUTES} * * * * root ${0} update" > $CRONJOB
-            $0 update
+        # if we use gnudip, enable gnudip.
+        gnudipServer=$(grep ^server= ${cfgfile} 2> /dev/null | cut -d = -f 2- |grep -v ^\'\')
+        if [ ! -f ${CFG} -a ! -z "${gnudipServer}" ];then
+            mv ${CFG_disabled} ${CFG}
         fi
+        # add a cronjob
+        echo "*/${UPDATEMINUTES} * * * * root ${0} update" > $CRONJOB
+        $0 update
     ;;
     get-nat)
         NAT=$(grep ^NAT $HELPERCFG 2> /dev/null | awk '{print $2}')

actions/gnudip

@@ -0,0 +1,77 @@
+#!/usr/bin/python3
+# -*- mode: python -*-
+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""
+GnuDIP client for updating Dynamic DNS records.
+"""
+
+import argparse
+import logging
+import pathlib
+import sys
+
+from plinth.modules.dynamicdns import gnudip
+
+logger = logging.getLogger(__name__)
+
+CONFIG_FILE = pathlib.Path('/etc/ez-ipupdate/ez-ipupdate.conf')
+
+
+def parse_arguments():
+    """Return parsed command line arguments as dictionary."""
+    parser = argparse.ArgumentParser()
+    subparsers = parser.add_subparsers(dest='subcommand', help='Sub command')
+
+    subparsers.add_parser('update', help='Update Dynamic DNS record')
+
+    subparsers.required = True
+    return parser.parse_args()
+
+
+def subcommand_update(_):
+    """Update Dynamic DNS record.
+
+    Uses settings from ez-ipupdate config file.
+    """
+    if not CONFIG_FILE.is_file():
+        logger.info('GnuDIP configuration not found.')
+        return
+
+    config = {}
+    with CONFIG_FILE.open() as cf:
+        lines = cf.readlines()
+        for line in lines:
+            if '=' in line:
+                items = line.split('=')
+                key = items[0].strip()
+                value = items[1].strip()
+            else:
+                key = line.strip()
+                value = True
+
+            config[key] = value
+
+    if not all(['host' in config, 'server' in config, 'user' in config]):
+        logger.warn('GnuDIP configuration is not complete.')
+        return
+
+    username, password = config['user'].split(':')
+    result, new_ip = gnudip.update(config['server'], config['host'], username,
+                                   password)
+    if result == 0 and new_ip:
+        print(new_ip)
+
+    return result
+
+
+def main():
+    """Parse arguments and perform all duties."""
+    arguments = parse_arguments()
+
+    subcommand = arguments.subcommand.replace('-', '_')
+    subcommand_method = globals()['subcommand_' + subcommand]
+    sys.exit(subcommand_method(arguments))
+
+
+if __name__ == '__main__':
+    main()

plinth/modules/dynamicdns/__init__.py

@@ -11,7 +11,6 @@ from plinth import cfg, menu
 from plinth.modules.backups.components import BackupRestore
 from plinth.modules.names.components import DomainType
 from plinth.modules.users.components import UsersAndGroups
-from plinth.package import Packages
 from plinth.signals import domain_added
 from plinth.utils import format_lazy
 
@@ -58,9 +57,6 @@ class DynamicDNSApp(app_module.App):
                               'dynamicdns:index', parent_url_name='system')
         self.add(menu_item)
 
-        packages = Packages('packages-dynamicdns', ['ez-ipupdate'])
-        self.add(packages)
-
         domain_type = DomainType('domain-type-dynamic',
                                  _('Dynamic Domain Name'), 'dynamicdns:index',
                                  can_have_certificate=True)

plinth/modules/dynamicdns/gnudip.py

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""
+GnuDIP client for updating Dynamic DNS records.
+"""
+
+import hashlib
+import logging
+import socket
+
+BUF_SIZE = 50
+GNUDIP_PORT = 3495
+
+logger = logging.getLogger(__name__)
+
+
+def update(server, domain, username, password):
+    """Update Dynamic DNS record."""
+    domain = domain.removeprefix(username + '.')
+    password_digest = hashlib.md5(password.encode()).hexdigest()
+
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+        logger.debug('Connecting to %s:%d', server, GNUDIP_PORT)
+        s.connect((server, GNUDIP_PORT))
+        salt = s.recv(BUF_SIZE).decode().strip()
+        salted_digest = password_digest + '.' + salt
+        final_digest = hashlib.md5(salted_digest.encode()).hexdigest()
+
+        update_request = username + ':' + final_digest + ':' + domain + ':2\n'
+        s.sendall(update_request.encode())
+
+        response = s.recv(BUF_SIZE).decode().strip()
+        result, new_ip = response.split(':')
+        result = int(result)
+        if result == 0:
+            logger.info('GnuDIP update success: %s', new_ip)
+        else:
+            logger.warn('GnuDIP update error: %s', response)
+
+        return result, new_ip