linkchecker/linkcheck/DNS/Lib.py

# -*- coding: iso-8859-1 -*-
"""
 $Id$

 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

from Base import DNSError

class UnpackError(DNSError): pass
class PackError(DNSError): pass

# Low-level 16 and 32 bit integer packing and unpacking

from struct import pack as struct_pack
from struct import unpack as struct_unpack

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):
    if type(addr) == type(0): return addr
    bytes = addr.split('.')
    if len(bytes) != 4: raise ValueError, 'bad IP address'
    n = 0
    for byte in bytes: n = n<<8 | int(byte)
    return n

def bin2addr(n):
    return '%d.%d.%d.%d' % ((n>>24)&0xFF, (n>>16)&0xFF,
                  (n>>8)&0xFF, n&0xFF)


# 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 label:
                if len(label) > 63:
                    raise PackError, 'label too long'
                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 = []
        for j in range(i):
            label = list[j]
            n = len(label)
            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())
        print res
    timing.finish()
    print timing.milli(), "ms total for unpacking"
    print round(timing.milli() / i, 4), 'ms per unpacking'


# 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
    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()
#
# $Log$
# Revision 1.5  2003/07/04 14:23:22  calvin
# add coding line
#
# Revision 1.4  2003/01/05 17:39:19  calvin
# pychecker fixes
#
# Revision 1.3  2002/11/26 23:27:43  calvin
# update to Python >= 2.2.1
#
# 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 Str<74>der.
#
# Revision 1.6  2001/07/19 07:39:18  anthony
# 'type' -> 'rrtype' in getRRheader(). Fix from Michael Str<74>der.
#
# 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
#
#