Import rndc.py from the python-rndc project verbatim

Bring in the pure-Python RNDC protocol client as-is, with no
modifications, so that subsequent cleanup and integration changes can
be reviewed against the pristine upstream source.

Source: python-rndc rndc.py (version 0.2.0)

Co-authored-by: Matthew Pounsett <matt@conundrum.com>
Assisted-by: Claude:claude-fable-5

diff --git a/bin/tests/system/isctest/rndc.py b/bin/tests/system/isctest/rndc.py
new file mode 100644 (file)
index 0000000..53a4eef
--- /dev/null
+++ b/bin/tests/system/isctest/rndc.py
@@ -0,0 +1,174 @@
+############################################################################
+# Copyright (C) 2016-2018  Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+#
+############################################################################
+# rndc.py
+# This module implements the RNDC control protocol.
+############################################################################
+
+import time
+import struct
+import hashlib
+import hmac
+import base64
+import random
+import socket
+
+__version__ = "0.2.0"
+
+
+class rndc:
+    """RNDC protocol client library"""
+    __algos = {
+        'md5': 157,
+        'sha1': 161,
+        'sha224': 162,
+        'sha256': 163,
+        'sha384': 164,
+        'sha512': 165
+    }
+
+    def __init__(self, host, algo, secret):
+        """Creates a persistent connection to RNDC and logs in
+        host - (ip, port) tuple
+        algo - HMAC algorithm, one of md5, sha1, sha224, sha256, sha384, sha512
+        secret - HMAC secret, base64 encoded"""
+        self.host = host
+        self.algo = algo
+        self.hlalgo = getattr(hashlib, algo)
+        self.secret = base64.b64decode(secret)
+        self.ser = random.randint(0, 1 << 24)
+        self.nonce = None
+        self.__connect_login()
+
+    def call(self, cmd):
+        """Call a RNDC command, all parsing is done on the server side
+        cmd - a complete command as bytes (eg b'reload zone example.com')
+        """
+        return dict(self.__command({b'type': cmd})[b'_data'])
+
+    def __serialize_dict(self, data, ignore_auth=False):
+        rv = b''
+        for k, v in data.items():
+            if ignore_auth and k == b'_auth':
+                continue
+            rv += bytes([len(k)])
+            rv += k
+            if isinstance(v, bytes):
+                rv += struct.pack('>BI', 1, len(v)) + v
+            elif isinstance(v, dict):
+                sd = self.__serialize_dict(v)
+                rv += struct.pack('>BI', 2, len(sd)) + sd
+            else:
+                raise NotImplementedError('Cannot serialize element of type %s'
+                                          % type(v))
+        return rv
+
+    def __prep_message(self, data):
+        self.ser += 1
+        now = int(time.time())
+
+        d = {}
+        d[b'_auth'] = {}
+        d[b'_ctrl'] = {}
+        d[b'_ctrl'][b'_ser'] = b'%d' % self.ser
+        d[b'_ctrl'][b'_tim'] = b'%d' % now
+        d[b'_ctrl'][b'_exp'] = b'%d' % (now + 60)
+        if self.nonce is not None:
+            d[b'_ctrl'][b'_nonce'] = self.nonce
+        d[b'_data'] = data
+
+        msg = self.__serialize_dict(d, ignore_auth=True)
+        hash = hmac.new(self.secret, msg, self.hlalgo).digest()
+        bhash = base64.b64encode(hash)
+        if self.algo == 'md5':
+            d[b'_auth'][b'hmd5'] = struct.pack('22s', bhash)
+        else:
+            d[b'_auth'][b'hsha'] = struct.pack('B88s',
+                                               self.__algos[self.algo], bhash)
+        msg = self.__serialize_dict(d)
+        msg = struct.pack('>II', len(msg) + 4, 1) + msg
+        return msg
+
+    def __verify_msg(self, msg):
+        if self.nonce is not None and msg[b'_ctrl'][b'_nonce'] != self.nonce:
+            return False
+        bhash = msg[b'_auth'][b'hmd5' if self.algo == 'md5' else b'hsha']
+        bhash += b'=' * (4 - (len(bhash) % 4))
+        remote_hash = base64.b64decode(bhash)
+        my_msg = self.__serialize_dict(msg, ignore_auth=True)
+        my_hash = hmac.new(self.secret, my_msg, self.hlalgo).digest()
+        return (my_hash == remote_hash)
+
+    def __command(self, data):
+        msg = self.__prep_message(data)
+        sent = self.socket.send(msg)
+        if sent != len(msg):
+            raise IOError("Cannot send the message")
+
+        header = self.socket.recv(8)
+        if len(header) != 8:
+            # What should we throw here? Bad auth can cause this...
+            raise IOError("Can't read response header")
+
+        length, version = struct.unpack('>II', header)
+        if version != 1:
+            raise NotImplementedError('Wrong message version %d' % version)
+
+        # it includes the header
+        length -= 4
+        data = self.socket.recv(length, socket.MSG_WAITALL)
+        if len(data) != length:
+            raise IOError("Can't read response data")
+
+        msg = self.__parse_message(data)
+        if not self.__verify_msg(msg):
+            raise IOError("Authentication failure")
+
+        return msg
+
+    def __connect_login(self):
+        self.socket = socket.create_connection(self.host)
+        self.nonce = None
+        msg = self.__command({b'type': b'null'})
+        self.nonce = msg[b'_ctrl'][b'_nonce']
+
+    def __parse_element(self, input):
+        pos = 0
+        labellen = input[pos]
+        pos += 1
+        label = input[pos:pos + labellen]
+        pos += labellen
+        type = input[pos]
+        pos += 1
+        datalen = struct.unpack('>I', input[pos:pos + 4])[0]
+        pos += 4
+        data = input[pos:pos + datalen]
+        pos += datalen
+        rest = input[pos:]
+
+        if type == 1:         # raw binary value
+            return label, data, rest
+        elif type == 2:       # dictionary
+            d = {}
+            while len(data) > 0:
+                ilabel, value, data = self.__parse_element(data)
+                d[ilabel] = value
+            return label, d, rest
+        # TODO type 3 - list
+        else:
+            raise NotImplementedError('Unknown element type %d' % type)
+
+    def __parse_message(self, input):
+        rv = {}
+        while len(input) > 0:
+            label, value, input = self.__parse_element(input)
+            rv[label] = value
+        return rv