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# -*- test-case-name: twisted.protocols.haproxy.test.test_v2parser -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
IProxyParser implementation for version two of the PROXY protocol.
"""
import binascii
import struct
from constantly import Values, ValueConstant
from zope.interface import implementer
from twisted.internet import address
from twisted.python import compat
from ._exceptions import (
convertError, InvalidProxyHeader, InvalidNetworkProtocol,
MissingAddressData
)
from . import _info
from . import _interfaces
class NetFamily(Values):
"""
Values for the 'family' field.
"""
UNSPEC = ValueConstant(0x00)
INET = ValueConstant(0x10)
INET6 = ValueConstant(0x20)
UNIX = ValueConstant(0x30)
class NetProtocol(Values):
"""
Values for 'protocol' field.
"""
UNSPEC = ValueConstant(0)
STREAM = ValueConstant(1)
DGRAM = ValueConstant(2)
_HIGH = 0b11110000
_LOW = 0b00001111
_LOCALCOMMAND = 'LOCAL'
_PROXYCOMMAND = 'PROXY'
@implementer(_interfaces.IProxyParser)
class V2Parser(object):
"""
PROXY protocol version two header parser.
Version two of the PROXY protocol is a binary format.
"""
PREFIX = b'\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A'
VERSIONS = [32]
COMMANDS = {0: _LOCALCOMMAND, 1: _PROXYCOMMAND}
ADDRESSFORMATS = {
# TCP4
17: '!4s4s2H',
18: '!4s4s2H',
# TCP6
33: '!16s16s2H',
34: '!16s16s2H',
# UNIX
49: '!108s108s',
50: '!108s108s',
}
def __init__(self):
self.buffer = b''
def feed(self, data):
"""
Consume a chunk of data and attempt to parse it.
@param data: A bytestring.
@type data: bytes
@return: A two-tuple containing, in order, a L{_interfaces.IProxyInfo}
and any bytes fed to the parser that followed the end of the
header. Both of these values are None until a complete header is
parsed.
@raises InvalidProxyHeader: If the bytes fed to the parser create an
invalid PROXY header.
"""
self.buffer += data
if len(self.buffer) < 16:
raise InvalidProxyHeader()
size = struct.unpack('!H', self.buffer[14:16])[0] + 16
if len(self.buffer) < size:
return (None, None)
header, remaining = self.buffer[:size], self.buffer[size:]
self.buffer = b''
info = self.parse(header)
return (info, remaining)
@staticmethod
def _bytesToIPv4(bytestring):
"""
Convert packed 32-bit IPv4 address bytes into a dotted-quad ASCII bytes
representation of that address.
@param bytestring: 4 octets representing an IPv4 address.
@type bytestring: L{bytes}
@return: a dotted-quad notation IPv4 address.
@rtype: L{bytes}
"""
return b'.'.join(
('%i' % (ord(b),)).encode('ascii')
for b in compat.iterbytes(bytestring)
)
@staticmethod
def _bytesToIPv6(bytestring):
"""
Convert packed 128-bit IPv6 address bytes into a colon-separated ASCII
bytes representation of that address.
@param bytestring: 16 octets representing an IPv6 address.
@type bytestring: L{bytes}
@return: a dotted-quad notation IPv6 address.
@rtype: L{bytes}
"""
hexString = binascii.b2a_hex(bytestring)
return b':'.join(
('%x' % (int(hexString[b:b+4], 16),)).encode('ascii')
for b in range(0, 32, 4)
)
@classmethod
def parse(cls, line):
"""
Parse a bytestring as a full PROXY protocol header.
@param line: A bytestring that represents a valid HAProxy PROXY
protocol version 2 header.
@type line: bytes
@return: A L{_interfaces.IProxyInfo} containing the
parsed data.
@raises InvalidProxyHeader: If the bytestring does not represent a
valid PROXY header.
"""
prefix = line[:12]
addrInfo = None
with convertError(IndexError, InvalidProxyHeader):
# Use single value slices to ensure bytestring values are returned
# instead of int in PY3.
versionCommand = ord(line[12:13])
familyProto = ord(line[13:14])
if prefix != cls.PREFIX:
raise InvalidProxyHeader()
version, command = versionCommand & _HIGH, versionCommand & _LOW
if version not in cls.VERSIONS or command not in cls.COMMANDS:
raise InvalidProxyHeader()
if cls.COMMANDS[command] == _LOCALCOMMAND:
return _info.ProxyInfo(line, None, None)
family, netproto = familyProto & _HIGH, familyProto & _LOW
with convertError(ValueError, InvalidNetworkProtocol):
family = NetFamily.lookupByValue(family)
netproto = NetProtocol.lookupByValue(netproto)
if (
family is NetFamily.UNSPEC or
netproto is NetProtocol.UNSPEC
):
return _info.ProxyInfo(line, None, None)
addressFormat = cls.ADDRESSFORMATS[familyProto]
addrInfo = line[16:16+struct.calcsize(addressFormat)]
if family is NetFamily.UNIX:
with convertError(struct.error, MissingAddressData):
source, dest = struct.unpack(addressFormat, addrInfo)
return _info.ProxyInfo(
line,
address.UNIXAddress(source.rstrip(b'\x00')),
address.UNIXAddress(dest.rstrip(b'\x00')),
)
addrType = 'TCP'
if netproto is NetProtocol.DGRAM:
addrType = 'UDP'
addrCls = address.IPv4Address
addrParser = cls._bytesToIPv4
if family is NetFamily.INET6:
addrCls = address.IPv6Address
addrParser = cls._bytesToIPv6
with convertError(struct.error, MissingAddressData):
info = struct.unpack(addressFormat, addrInfo)
source, dest, sPort, dPort = info
return _info.ProxyInfo(
line,
addrCls(addrType, addrParser(source), sPort),
addrCls(addrType, addrParser(dest), dPort),
)
|
