--- /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
+
+import socket
+import select
+import time
+import random
+
+import proto
+import rec
+import dn
+
+class error(Exception):
+ def __init__(self, text):
+ self.text = text
+
+ def __str__(self):
+ return self.text
+
+class servfail(error):
+ def __init__(self):
+ error.__init__(self, "SERVFAIL")
+
+class unreachable(error):
+ def __init__(self, server):
+ error.__init__(self, "could not reach server: " + str(server))
+
+def resolvecnames(pkt, res = None):
+ if res is None: res = default
+ for q in pkt.qlist:
+ cnrr = pkt.getanswer(q.name, rec.rtypebyname("CNAME"))
+ if cnrr is not None:
+ if pkt.getanswer(cnrr.data["priname"], q.rtype) is None:
+ try:
+ resp = res.squery(cnrr.data["priname"], q.rtype)
+ except error:
+ continue
+ if resp is None:
+ continue
+ anrr = resp.getanswer(cnrr.data["priname"], q.rtype)
+ if anrr is None:
+ continue
+ pkt.addan(anrr)
+
+def resolveadditional(pkt, rr, res = None):
+ if res is None: res = default
+ for name in rr.data:
+ if isinstance(rr.data[name], dn.domainname):
+ for rtype in ["A", "AAAA"]:
+ if pkt.getanswer(rr.data[name], rtype) is not None:
+ continue
+ try:
+ resp = res.squery(rr.data[name], rtype)
+ except error:
+ continue
+ if resp is None:
+ continue
+ anrr = resp.getanswer(rr.data[name], rtype)
+ if anrr is None:
+ continue
+ pkt.addad(anrr)
+
+def extractaddrinfo(packet, name):
+ ret = []
+ for rr in packet.anlist + packet.adlist:
+ if rr.head.name == name:
+ if rr.head.istype("A"):
+ ret += [(socket.AF_INET, socket.inet_ntop(socket.AF_INET, rr.data["address"]))]
+ elif rr.head.istype("AAAA"):
+ ret += [(socket.AF_INET6, socket.inet_ntop(socket.AF_INET6, rr.data["address"]))]
+ return ret
+
+def resolve(packet, nameserver, recurse, retries = 3, timeout = 2000, hops = 0, cnameres = None, verbose = False, visited = None):
+ if cnameres is None: cnameres = default
+ if visited is None: visited = set()
+ visited |= set([nameserver])
+ sk = socket.socket(nameserver[0], socket.SOCK_DGRAM)
+ sk.bind(("", 0))
+ for i in range(retries):
+ sk.sendto(packet.encode(), nameserver[1:])
+ p = select.poll()
+ p.register(sk.fileno(), select.POLLIN)
+ fds = p.poll(timeout)
+ if (sk.fileno(), select.POLLIN) in fds:
+ break
+ else:
+ raise unreachable(nameserver)
+ ret = sk.recv(65536)
+ sk.close()
+ try:
+ resp = proto.decodepacket(ret)
+ except proto.malformedpacket, inst:
+ raise error(str(inst))
+ if resp.qid != packet.qid:
+ raise error("got response with wrong qid(?!)")
+ if "resp" not in resp.flags:
+ raise error("got query in response")
+ if resp.rescode != 0:
+ if resp.rescode == proto.SERVFAIL:
+ raise servfail()
+ if resp.rescode == proto.NXDOMAIN:
+ return resp
+ raise error("non-successful response (" + str(resp.rescode) + ")")
+ if recurse:
+ resolvecnames(resp, cnameres)
+ if not recurse or resp.hasanswers():
+ return resp
+ if not resp.hasanswers() and "auth" in resp.flags:
+ return resp
+ if hops > 30:
+ raise error("too many levels deep")
+ for rr in resp.aulist:
+ if verbose:
+ print (hops * " ") + "Checking " + str(rr)
+ if rr.head.istype("NS"):
+ if verbose:
+ print (hops * " ") + "Will try " + str(rr)
+ ai = extractaddrinfo(resp, rr.data["nsname"])
+ if len(ai) == 0:
+ if verbose:
+ print (hops * " ") + "Resolving nameservers for " + str(rr.data["nsname"])
+ resolveadditional(resp, rr)
+ ai = extractaddrinfo(resp, rr.data["nsname"])
+ for ns in ai:
+ ns += (53,)
+ if ns in visited:
+ if verbose:
+ print (hops * " ") + "Will not try " + str(ns) + " again"
+ continue
+ if verbose:
+ print (hops * " ") + "Trying " + str(ns)
+ try:
+ resp2 = resolve(packet, ns, recurse, retries, timeout, hops + 1, verbose = verbose, visited = visited)
+ except unreachable:
+ if verbose:
+ print (hops * " ") + "Could not reach " + str(ns)
+ continue
+ if verbose:
+ if resp2 is None:
+ print (hops * " ") + "Got None"
+ else:
+ if "auth" in resp2.flags:
+ austr = "Auth"
+ else:
+ austr = "Nonauth"
+ print (hops * " ") + "Got " + str(resp2.hasanswers()) + " (" + austr + ")"
+ if resp2 is not None and resp2.hasanswers():
+ return resp2
+ if resp2 is not None and not resp2.hasanswers() and "auth" in resp2.flags:
+ return resp2
+ return None
+
+class resolver:
+ def __init__(self, nameserver, recurse, nsrecurse = True, retries = 3, timeout = 2000, verbose = False):
+ self.nameserver = nameserver
+ self.recurse = recurse
+ self.nsrecurse = nsrecurse
+ self.retries = retries
+ self.timeout = timeout
+ self.verbose = verbose
+
+ def resolve(self, packet):
+ return resolve(packet, self.nameserver, self.recurse, self.retries, self.timeout, verbose = self.verbose)
+
+ def squery(self, name, rtype):
+ packet = proto.packet()
+ try:
+ if self.nsrecurse: packet.setflags(["recurse"])
+ except AttributeError: pass
+ packet.addq(rec.rrhead(name, rtype))
+ return self.resolve(packet)
+
+class multiresolver(resolver):
+ def __init__(self, resolvers):
+ self.rl = [{"res": res, "qs": []} for res in resolvers]
+ self.lastclean = int(time.time())
+
+ def clean(self):
+ now = int(time.time())
+ if now - self.lastclean < 60:
+ return
+ self.lastclean = now
+ for r in self.rl:
+ nl = []
+ for q in r["qs"]:
+ if now - q["time"] < 1800:
+ nl += [q]
+ r["qs"] = nl
+
+ def resolve(self, packet):
+ self.clean()
+ l = []
+ ts = 0
+ for r in self.rl:
+ if len(r["qs"]) < 1:
+ score = 1.0
+ else:
+ score = float(sum([q["s"] for q in r["qs"]])) / len(r["qs"])
+ l += [(score, r)]
+ ts += score
+ c = random.random() * ts
+ for score, r in l:
+ c -= score
+ if c <= 0:
+ break
+ else:
+ assert(False)
+ try:
+ res = r["res"].resolve(packet)
+ except error:
+ r["qs"] = r["qs"][:10] + [{"time": int(time.time()), "s": 0}]
+ raise
+ r["qs"] = r["qs"][:10] + [{"time": int(time.time()), "s": 1}]
+ return res
+
+class sysresolver(resolver):
+ def __init__(self, conffile = "/etc/resolv.conf"):
+ nslist = []
+ prelist = []
+ a = open(conffile, "r")
+ for line in (l.strip() for l in a):
+ p = line.find(" ")
+ if p >= 0:
+ c = line[:p]
+ line = line[p + 1:]
+ if c == "nameserver":
+ try:
+ socket.inet_pton(socket.AF_INET, line)
+ except socket.error: pass
+ else:
+ nslist += [(socket.AF_INET, line, 53)]
+ try:
+ socket.inet_pton(socket.AF_INET6, line)
+ except socket.error: pass
+ else:
+ nslist += [(socket.AF_INET6, line, 53)]
+ if c == "domain" or c == "search": # How do these differ?
+ prelist += line.split()
+ a.close()
+ rl = []
+ for ns in nslist:
+ rl += [resolver(ns, False, True)]
+ self.resolver = multiresolver(rl)
+ self.prelist = []
+ for prefix in prelist:
+ pp = dn.fromstring(prefix)
+ pp.rooted = True
+ self.prelist += [pp]
+
+ def resolve(self, packet):
+ res = self.resolver.resolve(packet)
+ return res
+
+ def squery(self, name, rtype):
+ if type(name) == str:
+ name = dn.fromstring(name)
+ if not name.rooted:
+ namelist = [name + prefix for prefix in self.prelist] + [name + dn.fromstring(".")]
+ else:
+ namelist = [name]
+ for name in namelist:
+ packet = proto.packet()
+ packet.setflags(["recurse"])
+ packet.addq(rec.rrhead(name, rtype))
+ res = self.resolve(packet)
+ if res.rescode == 0:
+ break
+ return res
+
+sysres = sysresolver()
+rootresolvers = {"a": resolver((socket.AF_INET, "198.41.0.4", 53), True, False),
+ "b": resolver((socket.AF_INET, "192.228.79.201", 53), True, False),
+ "c": resolver((socket.AF_INET, "192.33.4.12", 53), True, False),
+ "d": resolver((socket.AF_INET, "128.8.10.90", 53), True, False),
+ "e": resolver((socket.AF_INET, "192.203.230.10", 53), True, False),
+ "f": resolver((socket.AF_INET, "192.5.5.241", 53), True, False),
+ "g": resolver((socket.AF_INET, "192.112.36.4", 53), True, False),
+ "h": resolver((socket.AF_INET, "128.63.2.53", 53), True, False),
+ "i": resolver((socket.AF_INET, "192.36.148.17", 53), True, False),
+ "j": resolver((socket.AF_INET, "192.58.128.30", 53), True, False),
+ "k": resolver((socket.AF_INET, "193.0.14.129", 53), True, False),
+ "l": resolver((socket.AF_INET, "198.32.64.12", 53), True, False),
+ "m": resolver((socket.AF_INET, "202.12.27.33", 53), True, False)
+ }
+rootres = multiresolver(rootresolvers.values())
+
+default = sysres
Dolda2000 GitWeb / ldd.git / blobdiff