# -*- encoding: utf-8 -*-
"""
$Id: Lib.py,v 1.11.2.7 2009/06/09 18:39:06 customdesigned Exp $
This file is part of the pydns project.
Homepage: http://pydns.sourceforge.net
This code is covered by the standard Python License.
Library code. Largely this is packers and unpackers for various types.
"""
#
#
# See RFC 1035:
# ------------------------------------------------------------------------
# Network Working Group P. Mockapetris
# Request for Comments: 1035 ISI
# November 1987
# Obsoletes: RFCs 882, 883, 973
#
# DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION
# ------------------------------------------------------------------------
import string, types
import Type
import Class
import Opcode
import Status
import DNS
from Base import DNSError
LABEL_UTF8 = False
LABEL_ENCODING = 'idna'
class UnpackError(DNSError): pass
class PackError(DNSError): pass
# Low-level 16 and 32 bit integer packing and unpacking
from struct import pack
from struct import unpack
from socket import inet_ntoa,inet_aton
def pack16bit(n):
return struct_pack('!H', n)
def pack32bit(n):
return struct_pack('!L', n)
def unpack16bit(s):
return struct_unpack('!H', s)[0]
def unpack32bit(s):
return struct_unpack('!L', s)[0]
def addr2bin(addr):
return struct_unpack('!l', inet_aton(addr))[0]
def bin2addr(n):
return inet_ntoa(struct_pack('!L', n))
# Packing class
class Packer:
" packer base class. supports basic byte/16bit/32bit/addr/string/name "
def __init__(self):
self.buf = ''
self.index = {}
def getbuf(self):
return self.buf
def addbyte(self, c):
if len(c) != 1: raise TypeError, 'one character expected'
self.buf = self.buf + c
def addbytes(self, bytes):
self.buf = self.buf + bytes
def add16bit(self, n):
self.buf = self.buf + pack16bit(n)
def add32bit(self, n):
self.buf = self.buf + pack32bit(n)
def addaddr(self, addr):
n = addr2bin(addr)
self.buf = self.buf + pack32bit(n)
def addstring(self, s):
if len(s) > 255:
raise ValueError, "Can't encode string of length "+ \
"%s (> 255)"%(len(s))
self.addbyte(chr(len(s)))
self.addbytes(s)
def addname(self, name):
# Domain name packing (section 4.1.4)
# Add a domain name to the buffer, possibly using pointers.
# The case of the first occurrence of a name is preserved.
# Redundant dots are ignored.
list = []
for label in string.splitfields(name, '.'):
if not label:
raise PackError, 'empty label'
list.append(label)
keys = []
for i in range(len(list)):
key = string.upper(string.joinfields(list[i:], '.'))
keys.append(key)
if self.index.has_key(key):
pointer = self.index[key]
break
else:
i = len(list)
pointer = None
# Do it into temporaries first so exceptions don't
# mess up self.index and self.buf
buf = ''
offset = len(self.buf)
index = []
if DNS.LABEL_UTF8:
enc = 'utf8'
else:
enc = DNS.LABEL_ENCODING
for j in range(i):
label = list[j]
try:
label = label.encode(enc)
except UnicodeEncodeError:
if not DNS.LABEL_UTF8: raise
if not label.startswith('\ufeff'):
label = '\ufeff'+label
label = label.encode(enc)
n = len(label)
if n > 63:
raise PackError, 'label too long'
if offset + len(buf) < 0x3FFF:
index.append((keys[j], offset + len(buf)))
else:
print 'DNS.Lib.Packer.addname:',
print 'warning: pointer too big'
buf = buf + (chr(n) + label)
if pointer:
buf = buf + pack16bit(pointer | 0xC000)
else:
buf = buf + '\0'
self.buf = self.buf + buf
for key, value in index:
self.index[key] = value
def dump(self):
keys = self.index.keys()
keys.sort()
print '-'*40
for key in keys:
print '%20s %3d' % (key, self.index[key])
print '-'*40
space = 1
for i in range(0, len(self.buf)+1, 2):
if self.buf[i:i+2] == '**':
if not space: print
space = 1
continue
space = 0
print '%4d' % i,
for c in self.buf[i:i+2]:
if ' ' < c < '\177':
print ' %c' % c,
else:
print '%2d' % ord(c),
print
print '-'*40
# Unpacking class
class Unpacker:
def __init__(self, buf):
self.buf = buf
self.offset = 0
def getbyte(self):
if self.offset >= len(self.buf):
raise UnpackError, "Ran off end of data"
c = self.buf[self.offset]
self.offset = self.offset + 1
return c
def getbytes(self, n):
s = self.buf[self.offset : self.offset + n]
if len(s) != n: raise UnpackError, 'not enough data left'
self.offset = self.offset + n
return s
def get16bit(self):
return unpack16bit(self.getbytes(2))
def get32bit(self):
return unpack32bit(self.getbytes(4))
def getaddr(self):
return bin2addr(self.get32bit())
def getstring(self):
return self.getbytes(ord(self.getbyte()))
def getname(self):
# Domain name unpacking (section 4.1.4)
c = self.getbyte()
i = ord(c)
if i & 0xC0 == 0xC0:
d = self.getbyte()
j = ord(d)
pointer = ((i<<8) | j) & ~0xC000
save_offset = self.offset
try:
self.offset = pointer
domain = self.getname()
finally:
self.offset = save_offset
return domain
if i == 0:
return ''
domain = self.getbytes(i)
remains = self.getname()
if not remains:
return domain
else:
return domain + '.' + remains
# Test program for packin/unpacking (section 4.1.4)
def testpacker():
N = 2500
R = range(N)
import timing
# See section 4.1.4 of RFC 1035
timing.start()
for i in R:
p = Packer()
p.addaddr('192.168.0.1')
p.addbytes('*' * 20)
p.addname('f.ISI.ARPA')
p.addbytes('*' * 8)
p.addname('Foo.F.isi.arpa')
p.addbytes('*' * 18)
p.addname('arpa')
p.addbytes('*' * 26)
p.addname('')
timing.finish()
print timing.milli(), "ms total for packing"
print round(timing.milli() / i, 4), 'ms per packing'
#p.dump()
u = Unpacker(p.buf)
u.getaddr()
u.getbytes(20)
u.getname()
u.getbytes(8)
u.getname()
u.getbytes(18)
u.getname()
u.getbytes(26)
u.getname()
timing.start()
for i in R:
u = Unpacker(p.buf)
res = (u.getaddr(),
u.getbytes(20),
u.getname(),
u.getbytes(8),
u.getname(),
u.getbytes(18),
u.getname(),
u.getbytes(26),
u.getname())
timing.finish()
print timing.milli(), "ms total for unpacking"
print round(timing.milli() / i, 4), 'ms per unpacking'
#for item in res: print item
# Pack/unpack RR toplevel format (section 3.2.1)
class RRpacker(Packer):
def __init__(self):
Packer.__init__(self)
self.rdstart = None
def addRRheader(self, name, type, klass, ttl, *rest):
self.addname(name)
self.add16bit(type)
self.add16bit(klass)
self.add32bit(ttl)
if rest:
if rest[1:]: raise TypeError, 'too many args'
rdlength = rest[0]
else:
rdlength = 0
self.add16bit(rdlength)
self.rdstart = len(self.buf)
def patchrdlength(self):
rdlength = unpack16bit(self.buf[self.rdstart-2:self.rdstart])
if rdlength == len(self.buf) - self.rdstart:
return
rdata = self.buf[self.rdstart:]
save_buf = self.buf
ok = 0
try:
self.buf = self.buf[:self.rdstart-2]
self.add16bit(len(rdata))
self.buf = self.buf + rdata
ok = 1
finally:
if not ok: self.buf = save_buf
def endRR(self):
if self.rdstart is not None:
self.patchrdlength()
self.rdstart = None
def getbuf(self):
if self.rdstart is not None: self.patchrdlength()
return Packer.getbuf(self)
# Standard RRs (section 3.3)
def addCNAME(self, name, klass, ttl, cname):
self.addRRheader(name, Type.CNAME, klass, ttl)
self.addname(cname)
self.endRR()
def addHINFO(self, name, klass, ttl, cpu, os):
self.addRRheader(name, Type.HINFO, klass, ttl)
self.addstring(cpu)
self.addstring(os)
self.endRR()
def addMX(self, name, klass, ttl, preference, exchange):
self.addRRheader(name, Type.MX, klass, ttl)
self.add16bit(preference)
self.addname(exchange)
self.endRR()
def addNS(self, name, klass, ttl, nsdname):
self.addRRheader(name, Type.NS, klass, ttl)
self.addname(nsdname)
self.endRR()
def addPTR(self, name, klass, ttl, ptrdname):
self.addRRheader(name, Type.PTR, klass, ttl)
self.addname(ptrdname)
self.endRR()
def addSOA(self, name, klass, ttl,
mname, rname, serial, refresh, retry, expire, minimum):
self.addRRheader(name, Type.SOA, klass, ttl)
self.addname(mname)
self.addname(rname)
self.add32bit(serial)
self.add32bit(refresh)
self.add32bit(retry)
self.add32bit(expire)
self.add32bit(minimum)
self.endRR()
def addTXT(self, name, klass, ttl, list):
self.addRRheader(name, Type.TXT, klass, ttl)
if type(list) is types.StringType:
list = [list]
for txtdata in list:
self.addstring(txtdata)
self.endRR()
# Internet specific RRs (section 3.4) -- class = IN
def addA(self, name, klass, ttl, address):
self.addRRheader(name, Type.A, klass, ttl)
self.addaddr(address)
self.endRR()
def addWKS(self, name, ttl, address, protocol, bitmap):
self.addRRheader(name, Type.WKS, Class.IN, ttl)
self.addaddr(address)
self.addbyte(chr(protocol))
self.addbytes(bitmap)
self.endRR()
def addSRV(self):
raise NotImplementedError
def prettyTime(seconds):
if seconds<60:
return seconds,"%d seconds"%(seconds)
if seconds<3600:
return seconds,"%d minutes"%(seconds/60)
if seconds<86400:
return seconds,"%d hours"%(seconds/3600)
if seconds<604800:
return seconds,"%d days"%(seconds/86400)
else:
return seconds,"%d weeks"%(seconds/604800)
class RRunpacker(Unpacker):
def __init__(self, buf):
Unpacker.__init__(self, buf)
self.rdend = None
def getRRheader(self):
name = self.getname()
rrtype = self.get16bit()
klass = self.get16bit()
ttl = self.get32bit()
rdlength = self.get16bit()
self.rdend = self.offset + rdlength
return (name, rrtype, klass, ttl, rdlength)
def endRR(self):
if self.offset != self.rdend:
raise UnpackError, 'end of RR not reached'
def getCNAMEdata(self):
return self.getname()
def getHINFOdata(self):
return self.getstring(), self.getstring()
def getMXdata(self):
return self.get16bit(), self.getname()
def getNSdata(self):
return self.getname()
def getPTRdata(self):
return self.getname()
def getSOAdata(self):
return self.getname(), \
self.getname(), \
('serial',)+(self.get32bit(),), \
('refresh ',)+prettyTime(self.get32bit()), \
('retry',)+prettyTime(self.get32bit()), \
('expire',)+prettyTime(self.get32bit()), \
('minimum',)+prettyTime(self.get32bit())
def getTXTdata(self):
list = []
while self.offset != self.rdend:
list.append(self.getstring())
return list
getSPFdata = getTXTdata
def getAdata(self):
return self.getaddr()
def getWKSdata(self):
address = self.getaddr()
protocol = ord(self.getbyte())
bitmap = self.getbytes(self.rdend - self.offset)
return address, protocol, bitmap
def getSRVdata(self):
"""
_Service._Proto.Name TTL Class SRV Priority Weight Port Target
"""
priority = self.get16bit()
weight = self.get16bit()
port = self.get16bit()
target = self.getname()
#print '***priority, weight, port, target', priority, weight, port, target
return priority, weight, port, target
# Pack/unpack Message Header (section 4.1)
class Hpacker(Packer):
def addHeader(self, id, qr, opcode, aa, tc, rd, ra, z, rcode,
qdcount, ancount, nscount, arcount):
self.add16bit(id)
self.add16bit((qr&1)<<15 | (opcode&0xF)<<11 | (aa&1)<<10
| (tc&1)<<9 | (rd&1)<<8 | (ra&1)<<7
| (z&7)<<4 | (rcode&0xF))
self.add16bit(qdcount)
self.add16bit(ancount)
self.add16bit(nscount)
self.add16bit(arcount)
class Hunpacker(Unpacker):
def getHeader(self):
id = self.get16bit()
flags = self.get16bit()
qr, opcode, aa, tc, rd, ra, z, rcode = (
(flags>>15)&1,
(flags>>11)&0xF,
(flags>>10)&1,
(flags>>9)&1,
(flags>>8)&1,
(flags>>7)&1,
(flags>>4)&7,
(flags>>0)&0xF)
qdcount = self.get16bit()
ancount = self.get16bit()
nscount = self.get16bit()
arcount = self.get16bit()
return (id, qr, opcode, aa, tc, rd, ra, z, rcode,
qdcount, ancount, nscount, arcount)
# Pack/unpack Question (section 4.1.2)
class Qpacker(Packer):
def addQuestion(self, qname, qtype, qclass):
self.addname(qname)
self.add16bit(qtype)
self.add16bit(qclass)
class Qunpacker(Unpacker):
def getQuestion(self):
return self.getname(), self.get16bit(), self.get16bit()
# Pack/unpack Message(section 4)
# NB the order of the base classes is important for __init__()!
class Mpacker(RRpacker, Qpacker, Hpacker):
pass
class Munpacker(RRunpacker, Qunpacker, Hunpacker):
pass
# Routines to print an unpacker to stdout, for debugging.
# These affect the unpacker's current position!
def dumpM(u):
print 'HEADER:',
(id, qr, opcode, aa, tc, rd, ra, z, rcode,
qdcount, ancount, nscount, arcount) = u.getHeader()
print 'id=%d,' % id,
print 'qr=%d, opcode=%d, aa=%d, tc=%d, rd=%d, ra=%d, z=%d, rcode=%d,' \
% (qr, opcode, aa, tc, rd, ra, z, rcode)
if tc: print '*** response truncated! ***'
if rcode: print '*** nonzero error code! (%d) ***' % rcode
print ' qdcount=%d, ancount=%d, nscount=%d, arcount=%d' \
% (qdcount, ancount, nscount, arcount)
for i in range(qdcount):
print 'QUESTION %d:' % i,
dumpQ(u)
for i in range(ancount):
print 'ANSWER %d:' % i,
dumpRR(u)
for i in range(nscount):
print 'AUTHORITY RECORD %d:' % i,
dumpRR(u)
for i in range(arcount):
print 'ADDITIONAL RECORD %d:' % i,
dumpRR(u)
class DnsResult:
def __init__(self,u,args):
self.header={}
self.questions=[]
self.answers=[]
self.authority=[]
self.additional=[]
self.args=args
self.storeM(u)
def show(self):
import time
print '; <<>> PDG.py 1.0 <<>> %s %s'%(self.args['name'],
self.args['qtype'])
opt=""
if self.args['rd']:
opt=opt+'recurs '
h=self.header
print ';; options: '+opt
print ';; got answer:'
print ';; ->>HEADER<<- opcode %s, status %s, id %d'%(
h['opcode'],h['status'],h['id'])
flags=filter(lambda x,h=h:h[x],('qr','aa','rd','ra','tc'))
print ';; flags: %s; Ques: %d, Ans: %d, Auth: %d, Addit: %d'%(
string.join(flags),h['qdcount'],h['ancount'],h['nscount'],
h['arcount'])
print ';; QUESTIONS:'
for q in self.questions:
print ';; %s, type = %s, class = %s'%(q['qname'],q['qtypestr'],
q['qclassstr'])
print
print ';; ANSWERS:'
for a in self.answers:
print '%-20s %-6s %-6s %s'%(a['name'],`a['ttl']`,a['typename'],
a['data'])
print
print ';; AUTHORITY RECORDS:'
for a in self.authority:
print '%-20s %-6s %-6s %s'%(a['name'],`a['ttl']`,a['typename'],
a['data'])
print
print ';; ADDITIONAL RECORDS:'
for a in self.additional:
print '%-20s %-6s %-6s %s'%(a['name'],`a['ttl']`,a['typename'],
a['data'])
print
if self.args.has_key('elapsed'):
print ';; Total query time: %d msec'%self.args['elapsed']
print ';; To SERVER: %s'%(self.args['server'])
print ';; WHEN: %s'%time.ctime(time.time())
def storeM(self,u):
(self.header['id'], self.header['qr'], self.header['opcode'],
self.header['aa'], self.header['tc'], self.header['rd'],
self.header['ra'], self.header['z'], self.header['rcode'],
self.header['qdcount'], self.header['ancount'],
self.header['nscount'], self.header['arcount']) = u.getHeader()
self.header['opcodestr']=Opcode.opcodestr(self.header['opcode'])
self.header['status']=Status.statusstr(self.header['rcode'])
for i in range(self.header['qdcount']):
#print 'QUESTION %d:' % i,
self.questions.append(self.storeQ(u))
for i in range(self.header['ancount']):
#print 'ANSWER %d:' % i,
self.answers.append(self.storeRR(u))
for i in range(self.header['nscount']):
#print 'AUTHORITY RECORD %d:' % i,
self.authority.append(self.storeRR(u))
for i in range(self.header['arcount']):
#print 'ADDITIONAL RECORD %d:' % i,
self.additional.append(self.storeRR(u))
def storeQ(self,u):
q={}
q['qname'], q['qtype'], q['qclass'] = u.getQuestion()
q['qtypestr']=Type.typestr(q['qtype'])
q['qclassstr']=Class.classstr(q['qclass'])
return q
def storeRR(self,u):
r={}
r['name'],r['type'],r['class'],r['ttl'],r['rdlength'] = u.getRRheader()
r['typename'] = Type.typestr(r['type'])
r['classstr'] = Class.classstr(r['class'])
#print 'name=%s, type=%d(%s), class=%d(%s), ttl=%d' \
# % (name,
# type, typename,
# klass, Class.classstr(class),
# ttl)
mname = 'get%sdata' % r['typename']
if hasattr(u, mname):
r['data']=getattr(u, mname)()
else:
r['data']=u.getbytes(r['rdlength'])
return r
def dumpQ(u):
qname, qtype, qclass = u.getQuestion()
print 'qname=%s, qtype=%d(%s), qclass=%d(%s)' \
% (qname,
qtype, Type.typestr(qtype),
qclass, Class.classstr(qclass))
def dumpRR(u):
name, type, klass, ttl, rdlength = u.getRRheader()
typename = Type.typestr(type)
print 'name=%s, type=%d(%s), class=%d(%s), ttl=%d' \
% (name,
type, typename,
klass, Class.classstr(klass),
ttl)
mname = 'get%sdata' % typename
if hasattr(u, mname):
print ' formatted rdata:', getattr(u, mname)()
else:
print ' binary rdata:', u.getbytes(rdlength)
if __name__ == "__main__":
testpacker()
#
# $Log: Lib.py,v $
# Revision 1.11.2.7 2009/06/09 18:39:06 customdesigned
# Built-in SPF support
#
# Revision 1.11.2.6 2008/10/15 22:34:06 customdesigned
# Default to idna encoding.
#
# Revision 1.11.2.5 2008/09/17 17:35:14 customdesigned
# Use 7-bit ascii encoding, because case folding needs to be disabled
# before utf8 is safe to use, even experimentally.
#
# Revision 1.11.2.4 2008/09/17 16:09:53 customdesigned
# Encode unicode labels as UTF-8
#
# Revision 1.11.2.3 2007/05/22 20:27:40 customdesigned
# Fix unpacker underflow.
#
# Revision 1.11.2.2 2007/05/22 20:25:53 customdesigned
# Use socket.inetntoa,inetaton.
#
# Revision 1.11.2.1 2007/05/22 20:20:39 customdesigned
# Mark utf-8 encoding
#
# Revision 1.11 2002/03/19 13:05:02 anthonybaxter
# converted to class based exceptions (there goes the python1.4 compatibility :)
#
# removed a quite gross use of 'eval()'.
#
# Revision 1.10 2002/03/19 12:41:33 anthonybaxter
# tabnannied and reindented everything. 4 space indent, no tabs.
# yay.
#
# Revision 1.9 2002/03/19 10:30:33 anthonybaxter
# first round of major bits and pieces. The major stuff here (summarised
# from my local, off-net CVS server :/ this will cause some oddities with
# the
#
# tests/testPackers.py:
# a large slab of unit tests for the packer and unpacker code in DNS.Lib
#
# DNS/Lib.py:
# placeholder for addSRV.
# added 'klass' to addA, make it the same as the other A* records.
# made addTXT check for being passed a string, turn it into a length 1 list.
# explicitly check for adding a string of length > 255 (prohibited).
# a bunch of cleanups from a first pass with pychecker
# new code for pack/unpack. the bitwise stuff uses struct, for a smallish
# (disappointly small, actually) improvement, while addr2bin is much
# much faster now.
#
# DNS/Base.py:
# added DiscoverNameServers. This automatically does the right thing
# on unix/ win32. No idea how MacOS handles this. *sigh*
# Incompatible change: Don't use ParseResolvConf on non-unix, use this
# function, instead!
# a bunch of cleanups from a first pass with pychecker
#
# Revision 1.8 2001/08/09 09:08:55 anthonybaxter
# added identifying header to top of each file
#
# Revision 1.7 2001/07/19 07:50:44 anthony
# Added SRV (RFC 2782) support. Code from Michael Strder.
#
# Revision 1.6 2001/07/19 07:39:18 anthony
# 'type' -> 'rrtype' in getRRheader(). Fix from Michael Strder.
#
# Revision 1.5 2001/07/19 07:34:19 anthony
# oops. glitch in storeRR (fixed now).
# Reported by Bastian Kleineidam and by greg lin.
#
# Revision 1.4 2001/07/19 07:16:42 anthony
# Changed (opcode&0xF)<<11 to (opcode*0xF)<<11.
# Patch from Timothy J. Miller.
#
# Revision 1.3 2001/07/19 06:57:07 anthony
# cvs keywords added
#
#
|