mirror of
https://github.com/samba-team/samba.git
synced 2024-12-24 21:34:56 +03:00
8bd71350ab
Autobuild-User: Jelmer Vernooij <jelmer@samba.org> Autobuild-Date: Sat Aug 27 17:40:39 CEST 2011 on sn-devel-104
326 lines
12 KiB
Python
326 lines
12 KiB
Python
# Copyright (C) 2001-2007, 2009-2011 Nominum, Inc.
|
|
#
|
|
# Permission to use, copy, modify, and distribute this software and its
|
|
# documentation for any purpose with or without fee is hereby granted,
|
|
# provided that the above copyright notice and this permission notice
|
|
# appear in all copies.
|
|
#
|
|
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
|
|
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
|
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
|
|
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
|
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
|
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
|
|
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
|
|
|
"""Help for building DNS wire format messages"""
|
|
|
|
import cStringIO
|
|
import struct
|
|
import random
|
|
import time
|
|
|
|
import dns.exception
|
|
import dns.tsig
|
|
|
|
QUESTION = 0
|
|
ANSWER = 1
|
|
AUTHORITY = 2
|
|
ADDITIONAL = 3
|
|
|
|
class Renderer(object):
|
|
"""Helper class for building DNS wire-format messages.
|
|
|
|
Most applications can use the higher-level L{dns.message.Message}
|
|
class and its to_wire() method to generate wire-format messages.
|
|
This class is for those applications which need finer control
|
|
over the generation of messages.
|
|
|
|
Typical use::
|
|
|
|
r = dns.renderer.Renderer(id=1, flags=0x80, max_size=512)
|
|
r.add_question(qname, qtype, qclass)
|
|
r.add_rrset(dns.renderer.ANSWER, rrset_1)
|
|
r.add_rrset(dns.renderer.ANSWER, rrset_2)
|
|
r.add_rrset(dns.renderer.AUTHORITY, ns_rrset)
|
|
r.add_edns(0, 0, 4096)
|
|
r.add_rrset(dns.renderer.ADDTIONAL, ad_rrset_1)
|
|
r.add_rrset(dns.renderer.ADDTIONAL, ad_rrset_2)
|
|
r.write_header()
|
|
r.add_tsig(keyname, secret, 300, 1, 0, '', request_mac)
|
|
wire = r.get_wire()
|
|
|
|
@ivar output: where rendering is written
|
|
@type output: cStringIO.StringIO object
|
|
@ivar id: the message id
|
|
@type id: int
|
|
@ivar flags: the message flags
|
|
@type flags: int
|
|
@ivar max_size: the maximum size of the message
|
|
@type max_size: int
|
|
@ivar origin: the origin to use when rendering relative names
|
|
@type origin: dns.name.Name object
|
|
@ivar compress: the compression table
|
|
@type compress: dict
|
|
@ivar section: the section currently being rendered
|
|
@type section: int (dns.renderer.QUESTION, dns.renderer.ANSWER,
|
|
dns.renderer.AUTHORITY, or dns.renderer.ADDITIONAL)
|
|
@ivar counts: list of the number of RRs in each section
|
|
@type counts: int list of length 4
|
|
@ivar mac: the MAC of the rendered message (if TSIG was used)
|
|
@type mac: string
|
|
"""
|
|
|
|
def __init__(self, id=None, flags=0, max_size=65535, origin=None):
|
|
"""Initialize a new renderer.
|
|
|
|
@param id: the message id
|
|
@type id: int
|
|
@param flags: the DNS message flags
|
|
@type flags: int
|
|
@param max_size: the maximum message size; the default is 65535.
|
|
If rendering results in a message greater than I{max_size},
|
|
then L{dns.exception.TooBig} will be raised.
|
|
@type max_size: int
|
|
@param origin: the origin to use when rendering relative names
|
|
@type origin: dns.name.Namem or None.
|
|
"""
|
|
|
|
self.output = cStringIO.StringIO()
|
|
if id is None:
|
|
self.id = random.randint(0, 65535)
|
|
else:
|
|
self.id = id
|
|
self.flags = flags
|
|
self.max_size = max_size
|
|
self.origin = origin
|
|
self.compress = {}
|
|
self.section = QUESTION
|
|
self.counts = [0, 0, 0, 0]
|
|
self.output.write('\x00' * 12)
|
|
self.mac = ''
|
|
|
|
def _rollback(self, where):
|
|
"""Truncate the output buffer at offset I{where}, and remove any
|
|
compression table entries that pointed beyond the truncation
|
|
point.
|
|
|
|
@param where: the offset
|
|
@type where: int
|
|
"""
|
|
|
|
self.output.seek(where)
|
|
self.output.truncate()
|
|
keys_to_delete = []
|
|
for k, v in self.compress.iteritems():
|
|
if v >= where:
|
|
keys_to_delete.append(k)
|
|
for k in keys_to_delete:
|
|
del self.compress[k]
|
|
|
|
def _set_section(self, section):
|
|
"""Set the renderer's current section.
|
|
|
|
Sections must be rendered order: QUESTION, ANSWER, AUTHORITY,
|
|
ADDITIONAL. Sections may be empty.
|
|
|
|
@param section: the section
|
|
@type section: int
|
|
@raises dns.exception.FormError: an attempt was made to set
|
|
a section value less than the current section.
|
|
"""
|
|
|
|
if self.section != section:
|
|
if self.section > section:
|
|
raise dns.exception.FormError
|
|
self.section = section
|
|
|
|
def add_question(self, qname, rdtype, rdclass=dns.rdataclass.IN):
|
|
"""Add a question to the message.
|
|
|
|
@param qname: the question name
|
|
@type qname: dns.name.Name
|
|
@param rdtype: the question rdata type
|
|
@type rdtype: int
|
|
@param rdclass: the question rdata class
|
|
@type rdclass: int
|
|
"""
|
|
|
|
self._set_section(QUESTION)
|
|
before = self.output.tell()
|
|
qname.to_wire(self.output, self.compress, self.origin)
|
|
self.output.write(struct.pack("!HH", rdtype, rdclass))
|
|
after = self.output.tell()
|
|
if after >= self.max_size:
|
|
self._rollback(before)
|
|
raise dns.exception.TooBig
|
|
self.counts[QUESTION] += 1
|
|
|
|
def add_rrset(self, section, rrset, **kw):
|
|
"""Add the rrset to the specified section.
|
|
|
|
Any keyword arguments are passed on to the rdataset's to_wire()
|
|
routine.
|
|
|
|
@param section: the section
|
|
@type section: int
|
|
@param rrset: the rrset
|
|
@type rrset: dns.rrset.RRset object
|
|
"""
|
|
|
|
self._set_section(section)
|
|
before = self.output.tell()
|
|
n = rrset.to_wire(self.output, self.compress, self.origin, **kw)
|
|
after = self.output.tell()
|
|
if after >= self.max_size:
|
|
self._rollback(before)
|
|
raise dns.exception.TooBig
|
|
self.counts[section] += n
|
|
|
|
def add_rdataset(self, section, name, rdataset, **kw):
|
|
"""Add the rdataset to the specified section, using the specified
|
|
name as the owner name.
|
|
|
|
Any keyword arguments are passed on to the rdataset's to_wire()
|
|
routine.
|
|
|
|
@param section: the section
|
|
@type section: int
|
|
@param name: the owner name
|
|
@type name: dns.name.Name object
|
|
@param rdataset: the rdataset
|
|
@type rdataset: dns.rdataset.Rdataset object
|
|
"""
|
|
|
|
self._set_section(section)
|
|
before = self.output.tell()
|
|
n = rdataset.to_wire(name, self.output, self.compress, self.origin,
|
|
**kw)
|
|
after = self.output.tell()
|
|
if after >= self.max_size:
|
|
self._rollback(before)
|
|
raise dns.exception.TooBig
|
|
self.counts[section] += n
|
|
|
|
def add_edns(self, edns, ednsflags, payload, options=None):
|
|
"""Add an EDNS OPT record to the message.
|
|
|
|
@param edns: The EDNS level to use.
|
|
@type edns: int
|
|
@param ednsflags: EDNS flag values.
|
|
@type ednsflags: int
|
|
@param payload: The EDNS sender's payload field, which is the maximum
|
|
size of UDP datagram the sender can handle.
|
|
@type payload: int
|
|
@param options: The EDNS options list
|
|
@type options: list of dns.edns.Option instances
|
|
@see: RFC 2671
|
|
"""
|
|
|
|
# make sure the EDNS version in ednsflags agrees with edns
|
|
ednsflags &= 0xFF00FFFFL
|
|
ednsflags |= (edns << 16)
|
|
self._set_section(ADDITIONAL)
|
|
before = self.output.tell()
|
|
self.output.write(struct.pack('!BHHIH', 0, dns.rdatatype.OPT, payload,
|
|
ednsflags, 0))
|
|
if not options is None:
|
|
lstart = self.output.tell()
|
|
for opt in options:
|
|
stuff = struct.pack("!HH", opt.otype, 0)
|
|
self.output.write(stuff)
|
|
start = self.output.tell()
|
|
opt.to_wire(self.output)
|
|
end = self.output.tell()
|
|
assert end - start < 65536
|
|
self.output.seek(start - 2)
|
|
stuff = struct.pack("!H", end - start)
|
|
self.output.write(stuff)
|
|
self.output.seek(0, 2)
|
|
lend = self.output.tell()
|
|
assert lend - lstart < 65536
|
|
self.output.seek(lstart - 2)
|
|
stuff = struct.pack("!H", lend - lstart)
|
|
self.output.write(stuff)
|
|
self.output.seek(0, 2)
|
|
after = self.output.tell()
|
|
if after >= self.max_size:
|
|
self._rollback(before)
|
|
raise dns.exception.TooBig
|
|
self.counts[ADDITIONAL] += 1
|
|
|
|
def add_tsig(self, keyname, secret, fudge, id, tsig_error, other_data,
|
|
request_mac, algorithm=dns.tsig.default_algorithm):
|
|
"""Add a TSIG signature to the message.
|
|
|
|
@param keyname: the TSIG key name
|
|
@type keyname: dns.name.Name object
|
|
@param secret: the secret to use
|
|
@type secret: string
|
|
@param fudge: TSIG time fudge
|
|
@type fudge: int
|
|
@param id: the message id to encode in the tsig signature
|
|
@type id: int
|
|
@param tsig_error: TSIG error code; default is 0.
|
|
@type tsig_error: int
|
|
@param other_data: TSIG other data.
|
|
@type other_data: string
|
|
@param request_mac: This message is a response to the request which
|
|
had the specified MAC.
|
|
@type request_mac: string
|
|
@param algorithm: the TSIG algorithm to use
|
|
@type algorithm: dns.name.Name object
|
|
"""
|
|
|
|
self._set_section(ADDITIONAL)
|
|
before = self.output.tell()
|
|
s = self.output.getvalue()
|
|
(tsig_rdata, self.mac, ctx) = dns.tsig.sign(s,
|
|
keyname,
|
|
secret,
|
|
int(time.time()),
|
|
fudge,
|
|
id,
|
|
tsig_error,
|
|
other_data,
|
|
request_mac,
|
|
algorithm=algorithm)
|
|
keyname.to_wire(self.output, self.compress, self.origin)
|
|
self.output.write(struct.pack('!HHIH', dns.rdatatype.TSIG,
|
|
dns.rdataclass.ANY, 0, 0))
|
|
rdata_start = self.output.tell()
|
|
self.output.write(tsig_rdata)
|
|
after = self.output.tell()
|
|
assert after - rdata_start < 65536
|
|
if after >= self.max_size:
|
|
self._rollback(before)
|
|
raise dns.exception.TooBig
|
|
self.output.seek(rdata_start - 2)
|
|
self.output.write(struct.pack('!H', after - rdata_start))
|
|
self.counts[ADDITIONAL] += 1
|
|
self.output.seek(10)
|
|
self.output.write(struct.pack('!H', self.counts[ADDITIONAL]))
|
|
self.output.seek(0, 2)
|
|
|
|
def write_header(self):
|
|
"""Write the DNS message header.
|
|
|
|
Writing the DNS message header is done asfter all sections
|
|
have been rendered, but before the optional TSIG signature
|
|
is added.
|
|
"""
|
|
|
|
self.output.seek(0)
|
|
self.output.write(struct.pack('!HHHHHH', self.id, self.flags,
|
|
self.counts[0], self.counts[1],
|
|
self.counts[2], self.counts[3]))
|
|
self.output.seek(0, 2)
|
|
|
|
def get_wire(self):
|
|
"""Return the wire format message.
|
|
|
|
@rtype: string
|
|
"""
|
|
|
|
return self.output.getvalue()
|