237 lines
8.4 KiB
Python
237 lines
8.4 KiB
Python
### Binder Models
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# Standard Imports
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import base64
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import binascii
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import socket
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# 3rd Party
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from cryptography.fernet import Fernet, InvalidToken
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from pybindxml import reader as bindreader
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import dns.exception
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import dns.query
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import dns.tsig
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import dns.tsigkeyring
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import dns.zone
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# App Imports
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from binder import exceptions
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from binder.backends import nsd
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from django.db import models
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from django.conf import settings
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from django.core.validators import MinValueValidator, MaxValueValidator
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from binder import helpers
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TSIG_ALGORITHMS = (('HMAC-MD5.SIG-ALG.REG.INT', 'MD5'),
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('hmac-sha1', 'SHA1'),
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('hmac-sha256', 'SHA256'),
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('hmac-sha384', 'SHA384'),
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('hmac-sha512', 'SHA512'))
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DNS_BACKENDS = (
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('BIND', 'Bind'),
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('NSD', 'NSD'),
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)
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class Key(models.Model):
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"""Store and reference TSIG keys."""
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name = models.CharField(max_length=255,
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unique=True,
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help_text="A human readable name for the key to "
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"store, used for further references to the key.")
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data = models.CharField(max_length=255,
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help_text="The TSIG key.")
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algorithm = models.CharField(max_length=255,
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choices=TSIG_ALGORITHMS,
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help_text="The algorithm which has been used "
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"for the key.")
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def __unicode__(self):
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return self.name
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def __str__(self):
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return self.name
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class Meta:
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ordering = ["name"]
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app_label = 'binder'
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def save(self, *args, **kwargs):
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f = Fernet(settings.FERNET_KEY)
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encrypted_text = f.encrypt(bytes(self.data, 'utf-8'))
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self.data = encrypted_text
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super(Key, self).save(*args, **kwargs)
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def create_keyring(self):
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if self.name is None:
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return None
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try:
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key_data = self.decrypt_keydata()
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keyring = dns.tsigkeyring.from_text({self.name: key_data})
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except binascii.Error as err:
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raise exceptions.KeyringException("Incorrect key data. Verify key: %s. Reason: %s" % (self.name, err))
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return keyring
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def decrypt_keydata(self, key=None):
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if key:
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fernet_key=key
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else:
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fernet_key=settings.FERNET_KEY
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try:
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f = Fernet(fernet_key)
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# self.data is returned as a string. so we need to re-convert it
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# to a byte string with just the key, then decrypt it.
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decrypted_key = f.decrypt(bytes(self.data[2:-1], 'utf-8'))
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except InvalidToken as err:
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raise exceptions.KeyringException()
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return str(decrypted_key)[2:-1]
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class BindServer(models.Model):
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"""Store DNS servers and attributes for referencing their control ports.
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Also reference FK for TSIG transfer keys, if required.
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"""
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hostname = models.CharField(max_length=255,
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unique=True,
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help_text="Host name or IP address of the BIND server.")
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dns_port = models.IntegerField(default=53,
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verbose_name="DNS port",
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validators=[
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MinValueValidator(1),
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MaxValueValidator(65535),
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],
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help_text="The port where the DNS server is listening for DNS "
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"requests. binder especially uses that port for the dynamic "
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"zone updates. In most cases you should always leave it at the "
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"default port 53.")
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server_type = models.CharField(
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help_text="DNS Server Type.",
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choices=DNS_BACKENDS,
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default='BIND',
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max_length=20)
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control_port = models.IntegerField(
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default=0,
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validators=[
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MinValueValidator(1),
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MaxValueValidator(65535),
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],
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help_text="Port where the DNS server accepts remote statistic or control commands. "
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"8053 for BIND, 8952 for NSD.")
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default_transfer_key = models.ForeignKey(Key,
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on_delete=models.SET_NULL,
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null=True,
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help_text="The default key to use for all actions "
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"with this DNS server.")
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def __unicode__(self):
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return self.hostname
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def __str__(self):
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return self.hostname
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class Meta:
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ordering = ["hostname"]
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app_label = 'binder'
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def save(self, *args, **kwargs):
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if self.server_type == 'NSD':
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server = nsd.NSDServer(hostname=self.hostname, control_port=self.control_port)
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server.write_config()
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super().save(*args, **kwargs)
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def list_zones(self):
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"""List the DNS zones and attributes.
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TODO: Parse these XML more intelligently. Grab the view name. Any other data available?
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Returns:
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List of Dicts { String view_name,
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String zone_name,
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String zone_class,
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String zone_serial }
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"""
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if self.server_type == "BIND":
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# TODO: just return stats from get_stats call. This is probably not used
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# anywhere else.
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zone_data = bindreader.BindXmlReader(host=self.hostname, port=self.control_port)
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zone_data.get_stats()
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return zone_data
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elif self.server_type == "NSD":
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zone_data = nsd.NSDServer(hostname=self.hostname,
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control_port=self.control_port)
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zone_dict = zone_data.get_zone_list()
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return zone_dict
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def list_zone_records(self, zone_name):
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"""List all records in a specific zone.
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TODO: Print out current_record in the loop and see if we can parse this more programatically,
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rather than just splitting on space. What is the difference between class and type?
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Arguments:
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String zone_name: Name of the zone
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Returns:
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List of Dicts { String rr_name, String rr_ttl, String rr_class, String rr_type, String rr_data }
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"""
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try:
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transfer_key = Key.objects.get(name=self.default_transfer_key)
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except Key.DoesNotExist:
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keyring = None
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algorithm = None
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else:
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keyring = transfer_key.create_keyring()
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algorithm = transfer_key.algorithm
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try:
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xfr = dns.query.xfr(
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helpers.ip_address(self.hostname),
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zone_name,
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port=self.dns_port,
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keyring=keyring,
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keyalgorithm=algorithm)
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zone = dns.zone.from_xfr(xfr)
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except dns.tsig.PeerBadKey:
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# The incorrect TSIG key was selected for transfers.
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raise exceptions.TransferException("Unable to list zone records because of a TSIG key mismatch.")
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except socket.error as err:
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# Thrown when the DNS server does not respond for a zone transfer (XFR).
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raise exceptions.TransferException("DNS server did not respond for transfer. Reason: %s" % err)
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except dns.exception.FormError:
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# When the DNS message is malformed.
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# * Can happen if a TSIG key is required but a default_transfer_key is not specified.
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raise exceptions.TransferException("Unable to perform AXFR to list zone records. Did you forget to specify a default transfer key?")
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names = zone.nodes.keys()
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sorted(names)
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record_array = []
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for current_name in names:
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current_record = zone[current_name].to_text(current_name)
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for split_record in current_record.split("\n"):
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current_record = split_record.split(" ")
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rr_dict = {}
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rr_dict["rr_name"] = current_record[0]
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rr_dict["rr_ttl"] = current_record[1]
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rr_dict["rr_class"] = current_record[2]
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rr_dict["rr_type"] = current_record[3]
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rr_dict["rr_data"] = current_record[4]
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record_array.append(rr_dict)
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return record_array
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