--- /dev/null
+# ldd - DNS implementation in Python
+# Copyright (C) 2006 Fredrik Tolf <fredrik@dolda2000.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+from random import randint
+import struct
+
+import dn
+import rec
+
+class malformedpacket(Exception):
+ def __init__(self, text, qid):
+ self.text = text
+ self.qid = qid
+
+ def __str__(self):
+ return self.text
+
+class packet:
+ "An abstract representation of a DNS query"
+
+ def __init__(self, qid = None, flags = 0, addr = None):
+ if qid is None: qid = randint(0, 65535)
+ self.qid = qid
+ self.qlist = []
+ self.anlist = []
+ self.aulist = []
+ self.adlist = []
+ self.opcode = 0
+ self.rescode = 0
+ self.addr = addr
+ self.signed = False
+ self.tsigctx = None
+ if type(flags) == int:
+ self.initflags(flags)
+ elif type(flags) == set:
+ self.flags = flags
+ else:
+ self.flags = set(flags)
+
+ def setflags(self, flags):
+ flags = set(flags)
+ self.flags |= flags
+
+ def clrflags(self, flags):
+ flags = set(flags)
+ self.flags -= flags
+
+ def initflags(self, flags):
+ nf = set()
+ if flags & 0x8000: nf.add("resp")
+ if flags & 0x0400: nf.add("auth")
+ if flags & 0x0200: nf.add("trunc")
+ if flags & 0x0100: nf.add("recurse")
+ if flags & 0x0080: nf.add("recursed")
+ if flags & 0x0020: nf.add("isauthen")
+ if flags & 0x0010: nf.add("authok")
+ self.opcode = (flags & 0x7800) >> 11
+ self.rescode = flags & 0x000f
+ self.flags = nf
+
+ def encodeflags(self):
+ ret = 0
+ if "resp" in self.flags: ret |= 0x8000
+ if "auth" in self.flags: ret |= 0x0400
+ if "trunc" in self.flags: ret |= 0x0200
+ if "recurse" in self.flags: ret |= 0x0100
+ if "recursed" in self.flags: ret |= 0x0080
+ if "authok" in self.flags: ret |= 0x0010
+ ret |= self.opcode << 11
+ ret |= self.rescode
+ return ret
+
+ def addq(self, rr):
+ self.qlist.append(rr)
+
+ def addan(self, rr):
+ for rr2 in self.anlist:
+ if rr2.head == rr.head and rr2.data == rr.data:
+ break
+ else:
+ self.anlist.append(rr)
+
+ def addau(self, rr):
+ for rr2 in self.aulist:
+ if rr2.head == rr.head and rr2.data == rr.data:
+ break
+ else:
+ self.aulist.append(rr)
+
+ def addad(self, rr):
+ for rr2 in self.adlist:
+ if rr2.head == rr.head and rr2.data == rr.data:
+ break
+ else:
+ self.adlist.append(rr)
+
+ def allrrs(self):
+ return self.anlist + self.aulist + self.adlist
+
+ def merge(self, other):
+ for lst in ["anlist", "aulist", "adlist"]:
+ for rr in getattr(other, lst):
+ for rr2 in getattr(self, lst):
+ if rr2.head == rr.head and rr2.data == rr.data:
+ break
+ else:
+ getattr(self, lst).append(rr)
+
+ def getanswer(self, name, rtype):
+ for rr in self.anlist + self.aulist + self.adlist:
+ if rr.head.istype(rtype) and rr.head.name == name:
+ return rr
+ return None
+
+ def hasanswers(self):
+ for q in self.qlist:
+ for rr in self.anlist + self.aulist + self.adlist:
+ if rr.head.rtype == q.rtype and rr.head.name == q.name:
+ break
+ if rr.head.istype("CNAME") and rr.head.name == q.name and self.getanswer(rr.data["priname"], q.rtype) is not None:
+ break
+ else:
+ break
+ else:
+ return True
+ return False
+
+ def __str__(self):
+ ret = ""
+ ret += "ID: " + str(self.qid) + "\n"
+ ret += "Flags: " + str(self.flags) + "\n"
+ ret += "Opcode: " + str(self.opcode) + "\n"
+ ret += "Resp. code: " + str(self.rescode) + "\n"
+ ret += "Queries:\n"
+ for rr in self.qlist:
+ ret += "\t" + str(rr) + "\n"
+ ret += "Answers:\n"
+ for rr in self.anlist:
+ ret += "\t" + str(rr) + "\n"
+ ret += "Auth RRs:\n"
+ for rr in self.aulist:
+ ret += "\t" + str(rr) + "\n"
+ ret += "Additional RRs:\n"
+ for rr in self.adlist:
+ ret += "\t" + str(rr) + "\n"
+ return ret
+
+ def encode(self):
+ ret = ""
+ ret += struct.pack(">6H", self.qid, self.encodeflags(), len(self.qlist), len(self.anlist), len(self.aulist), len(self.adlist))
+ offset = len(ret)
+ names = []
+ for rr in self.qlist:
+ rre, names = rr.encode(names, offset)
+ offset += len(rre)
+ ret += rre
+ for rr in self.anlist:
+ rre, names = rr.encode(names, offset)
+ offset += len(rre)
+ ret += rre
+ for rr in self.aulist:
+ rre, names = rr.encode(names, offset)
+ offset += len(rre)
+ ret += rre
+ for rr in self.adlist:
+ rre, names = rr.encode(names, offset)
+ offset += len(rre)
+ ret += rre
+ return ret
+
+def decodepacket(string):
+ offset = struct.calcsize(">6H")
+ qid, flags, qno, anno, auno, adno = struct.unpack(">6H", string[0:offset])
+ ret = packet(qid, flags)
+ try:
+ for i in range(qno):
+ crr, offset = rec.rrhead.decode(string, offset)
+ ret.addq(crr)
+ for i in range(anno):
+ crr, offset = rec.rr.decode(string, offset)
+ ret.addan(crr)
+ for i in range(auno):
+ crr, offset = rec.rr.decode(string, offset)
+ ret.addau(crr)
+ for i in range(adno):
+ crr, offset = rec.rr.decode(string, offset)
+ ret.addad(crr)
+ except rec.malformedrr, inst:
+ raise malformedpacket(str(inst), qid)
+ return ret
+
+def responsefor(pkt, rescode = 0):
+ resp = packet(pkt.qid, ["resp"])
+ resp.opcode = pkt.opcode
+ resp.rescode = rescode
+ resp.tsigctx = pkt.tsigctx
+ resp.qlist = pkt.qlist + [] # Make a copy
+ return resp
+
+def decodename(packet, offset):
+ parts = []
+ while True:
+ clen = ord(packet[offset])
+ offset += 1
+ if clen & 0xc0:
+ my = dn.domainname(parts, False)
+ cont, = struct.unpack(">H", chr(clen & 0x3f) + packet[offset])
+ res, discard = decodename(packet, cont)
+ return my + res, offset + 1
+ elif clen == 0:
+ return dn.domainname(parts, True), offset
+ else:
+ parts.append(packet[offset:offset + clen])
+ offset += clen
+
+def encodename(dn, names, offset):
+ ret = ""
+ for i in range(len(dn)):
+ for name, off in names:
+ if name == dn[i:]:
+ ret += chr(0xc0 + (off >> 8))
+ ret += chr(off & 0xff)
+ offset += 2
+ return ret, names
+ if offset < 16384:
+ names += [(dn[i:], offset)]
+ ret += chr(len(dn.parts[i]))
+ ret += dn.parts[i]
+ offset += 1 + len(dn.parts[i])
+ ret += chr(0)
+ offset += 1
+ return ret, names
+
+# Opcode constants
+QUERY = 0
+IQUERY = 1
+STATUS = 2
+UPDATE = 5
+
+# Response code constants
+# RFC 1035:
+FORMERR = 1
+SERVFAIL = 2
+NXDOMAIN = 3
+NOTIMP = 4
+REFUSED = 5
+# RFC 2136:
+YXDOMAIN = 6
+YXRRSET = 7
+NXRRSET = 8
+NOTAUTH = 9
+NOTZONE = 10
+# RFC 2845:
+BADSIG = 16
+BADKEY = 17
+BADTIME = 18
+
+# Special RR types
+QTANY = 255
+QTMAILA = 254
+QTMAILB = 253
+QTAXFR = 252
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