/usr/lib/python2.7/dist-packages/maxminddb/reader.py is in python-maxminddb 1.2.3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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maxminddb.reader
~~~~~~~~~~~~~~~~
This module contains the pure Python database reader and related classes.
"""
from __future__ import unicode_literals
try:
import mmap
except ImportError:
# pylint: disable=invalid-name
mmap = None
import struct
from maxminddb.compat import byte_from_int, compat_ip_address
from maxminddb.const import MODE_AUTO, MODE_MMAP, MODE_FILE, MODE_MEMORY
from maxminddb.decoder import Decoder
from maxminddb.errors import InvalidDatabaseError
from maxminddb.file import FileBuffer
class Reader(object):
"""
Instances of this class provide a reader for the MaxMind DB format. IP
addresses can be looked up using the ``get`` method.
"""
_DATA_SECTION_SEPARATOR_SIZE = 16
_METADATA_START_MARKER = b"\xAB\xCD\xEFMaxMind.com"
_ipv4_start = None
def __init__(self, database, mode=MODE_AUTO):
"""Reader for the MaxMind DB file format
Arguments:
database -- A path to a valid MaxMind DB file such as a GeoIP2
database file.
mode -- mode to open the database with. Valid mode are:
* MODE_MMAP - read from memory map.
* MODE_FILE - read database as standard file.
* MODE_MEMORY - load database into memory.
* MODE_AUTO - tries MODE_MMAP and then MODE_FILE. Default.
"""
# pylint: disable=redefined-variable-type
if (mode == MODE_AUTO and mmap) or mode == MODE_MMAP:
with open(database, 'rb') as db_file:
self._buffer = mmap.mmap(
db_file.fileno(), 0, access=mmap.ACCESS_READ)
self._buffer_size = self._buffer.size()
elif mode in (MODE_AUTO, MODE_FILE):
self._buffer = FileBuffer(database)
self._buffer_size = self._buffer.size()
elif mode == MODE_MEMORY:
with open(database, 'rb') as db_file:
self._buffer = db_file.read()
self._buffer_size = len(self._buffer)
else:
raise ValueError(
'Unsupported open mode ({0}). Only MODE_AUTO, '
' MODE_FILE, and MODE_MEMORY are support by the pure Python '
'Reader'.format(mode))
metadata_start = self._buffer.rfind(
self._METADATA_START_MARKER, max(0,
self._buffer_size - 128 * 1024))
if metadata_start == -1:
self.close()
raise InvalidDatabaseError('Error opening database file ({0}). '
'Is this a valid MaxMind DB file?'
''.format(database))
metadata_start += len(self._METADATA_START_MARKER)
metadata_decoder = Decoder(self._buffer, metadata_start)
(metadata, _) = metadata_decoder.decode(metadata_start)
self._metadata = Metadata(**metadata) # pylint: disable=bad-option-value
self._decoder = Decoder(self._buffer, self._metadata.search_tree_size +
self._DATA_SECTION_SEPARATOR_SIZE)
def metadata(self):
"""Return the metadata associated with the MaxMind DB file"""
return self._metadata
def get(self, ip_address):
"""Return the record for the ip_address in the MaxMind DB
Arguments:
ip_address -- an IP address in the standard string notation
"""
address = compat_ip_address(ip_address)
if address.version == 6 and self._metadata.ip_version == 4:
raise ValueError(
'Error looking up {0}. You attempted to look up '
'an IPv6 address in an IPv4-only database.'.format(ip_address))
pointer = self._find_address_in_tree(address)
return self._resolve_data_pointer(pointer) if pointer else None
def _find_address_in_tree(self, ip_address):
packed = bytearray(ip_address.packed)
bit_count = len(packed) * 8
node = self._start_node(bit_count)
for i in range(bit_count):
if node >= self._metadata.node_count:
break
bit = 1 & (packed[i >> 3] >> 7 - (i % 8))
node = self._read_node(node, bit)
if node == self._metadata.node_count:
# Record is empty
return 0
elif node > self._metadata.node_count:
return node
raise InvalidDatabaseError('Invalid node in search tree')
def _start_node(self, length):
if self._metadata.ip_version != 6 or length == 128:
return 0
# We are looking up an IPv4 address in an IPv6 tree. Skip over the
# first 96 nodes.
if self._ipv4_start:
return self._ipv4_start
node = 0
for _ in range(96):
if node >= self._metadata.node_count:
break
node = self._read_node(node, 0)
self._ipv4_start = node
return node
def _read_node(self, node_number, index):
base_offset = node_number * self._metadata.node_byte_size
record_size = self._metadata.record_size
if record_size == 24:
offset = base_offset + index * 3
node_bytes = b'\x00' + self._buffer[offset:offset + 3]
elif record_size == 28:
(middle, ) = struct.unpack(
b'!B', self._buffer[base_offset + 3:base_offset + 4])
if index:
middle &= 0x0F
else:
middle = (0xF0 & middle) >> 4
offset = base_offset + index * 4
node_bytes = byte_from_int(middle) + self._buffer[offset:offset +
3]
elif record_size == 32:
offset = base_offset + index * 4
node_bytes = self._buffer[offset:offset + 4]
else:
raise InvalidDatabaseError('Unknown record size: {0}'.format(
record_size))
return struct.unpack(b'!I', node_bytes)[0]
def _resolve_data_pointer(self, pointer):
resolved = pointer - self._metadata.node_count + \
self._metadata.search_tree_size
if resolved > self._buffer_size:
raise InvalidDatabaseError(
"The MaxMind DB file's search tree is corrupt")
(data, _) = self._decoder.decode(resolved)
return data
def close(self):
"""Closes the MaxMind DB file and returns the resources to the system"""
# pylint: disable=unidiomatic-typecheck
if type(self._buffer) not in (str, bytes):
self._buffer.close()
class Metadata(object):
"""Metadata for the MaxMind DB reader"""
# pylint: disable=too-many-instance-attributes
def __init__(self, **kwargs):
"""Creates new Metadata object. kwargs are key/value pairs from spec"""
# Although I could just update __dict__, that is less obvious and it
# doesn't work well with static analysis tools and some IDEs
self.node_count = kwargs['node_count']
self.record_size = kwargs['record_size']
self.ip_version = kwargs['ip_version']
self.database_type = kwargs['database_type']
self.languages = kwargs['languages']
self.binary_format_major_version = kwargs[
'binary_format_major_version']
self.binary_format_minor_version = kwargs[
'binary_format_minor_version']
self.build_epoch = kwargs['build_epoch']
self.description = kwargs['description']
@property
def node_byte_size(self):
"""The size of a node in bytes"""
return self.record_size // 4
@property
def search_tree_size(self):
"""The size of the search tree"""
return self.node_count * self.node_byte_size
def __repr__(self):
args = ', '.join('%s=%r' % x for x in self.__dict__.items())
return '{module}.{class_name}({data})'.format(
module=self.__module__,
class_name=self.__class__.__name__,
data=args)
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