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| Current File : //usr/share/authconfig/dnsclient.py |
#
# Copyright 2001, 2005 Red Hat, Inc.
#
# This 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 Street, Fifth Floor, Boston, MA 02110-1301, USA
import struct
import socket
import sys
import acutil
DNS_C_IN = 1
DNS_C_CS = 2
DNS_C_CHAOS = 3
DNS_C_HS = 4
DNS_C_ANY = 255
DNS_T_A = 1
DNS_T_NS = 2
DNS_T_CNAME = 5
DNS_T_SOA = 6
DNS_T_NULL = 10
DNS_T_WKS = 11
DNS_T_PTR = 12
DNS_T_HINFO = 13
DNS_T_MX = 15
DNS_T_TXT = 16
DNS_T_SRV = 33
DNS_T_ANY = 255
DEBUG_DNSCLIENT = False
class DNSQueryHeader:
FORMAT = "!HBBHHHH"
def __init__(self):
self.dns_id = 0
self.dns_rd = 0
self.dns_tc = 0
self.dns_aa = 0
self.dns_opcode = 0
self.dns_qr = 0
self.dns_rcode = 0
self.dns_z = 0
self.dns_ra = 0
self.dns_qdcount = 0
self.dns_ancount = 0
self.dns_nscount = 0
self.dns_arcount = 0
def pack(self):
return struct.pack(DNSQueryHeader.FORMAT,
self.dns_id,
(self.dns_rd & 1) |
(self.dns_tc & 1) << 1 |
(self.dns_aa & 1) << 2 |
(self.dns_opcode & 15) << 3 |
(self.dns_qr & 1) << 7,
(self.dns_rcode & 15) |
(self.dns_z & 7) << 4 |
(self.dns_ra & 1) << 7,
self.dns_qdcount,
self.dns_ancount,
self.dns_nscount,
self.dns_arcount)
def unpack(self, data):
(self.dns_id, byte1, byte2, self.dns_qdcount, self.dns_ancount,
self.dns_nscount, self.dns_arcount) = struct.unpack(DNSQueryHeader.FORMAT, data[0:self.size()])
self.dns_rd = byte1 & 1
self.dns_tc = (byte1 >> 1) & 1
self.dns_aa = (byte1 >> 2) & 1
self.dns_opcode = (byte1 >> 3) & 15
self.dns_qr = (byte1 >> 7) & 1
self.dns_rcode = byte2 & 15
self.dns_z = (byte2 >> 4) & 7
self.dns_ra = (byte1 >> 7) & 1
def size(self):
return struct.calcsize(DNSQueryHeader.FORMAT)
def unpackQueryHeader(data):
header = DNSQueryHeader()
header.unpack(data)
return header
class DNSResult:
FORMAT = "!HHIH"
QFORMAT = "!HH"
def __init__(self):
self.dns_name = ""
self.dns_type = 0
self.dns_class = 0
self.dns_ttl = 0
self.dns_rlength = 0
self.rdata = None
def unpack(self, data):
(self.dns_type, self.dns_class, self.dns_ttl,
self.dns_rlength) = struct.unpack(DNSResult.FORMAT, data[0:self.size()])
def qunpack(self, data):
(self.dns_type, self.dns_class) = struct.unpack(DNSResult.QFORMAT, data[0:self.qsize()])
def size(self):
return struct.calcsize(DNSResult.FORMAT)
def qsize(self):
return struct.calcsize(DNSResult.QFORMAT)
class DNSRData:
def __init__(self):
pass
#typedef struct dns_rr_a {
# u_int32_t address;
#} dns_rr_a_t;
#
#typedef struct dns_rr_cname {
# const char *cname;
#} dns_rr_cname_t;
#
#typedef struct dns_rr_hinfo {
# const char *cpu, *os;
#} dns_rr_hinfo_t;
#
#typedef struct dns_rr_mx {
# u_int16_t preference;
# const char *exchange;
#} dns_rr_mx_t;
#
#typedef struct dns_rr_null {
# unsigned const char *data;
#} dns_rr_null_t;
#
#typedef struct dns_rr_ns {
# const char *nsdname;
#} dns_rr_ns_t;
#
#typedef struct dns_rr_ptr {
# const char *ptrdname;
#} dns_rr_ptr_t;
#
#typedef struct dns_rr_soa {
# const char *mname;
# const char *rname;
# u_int32_t serial;
# int32_t refresh;
# int32_t retry;
# int32_t expire;
# int32_t minimum;
#} dns_rr_soa_t;
#
#typedef struct dns_rr_txt {
# const char *data;
#} dns_rr_txt_t;
#
#typedef struct dns_rr_srv {
# const char *server;
# u_int16_t priority;
# u_int16_t weight;
# u_int16_t port;
#} dns_rr_srv_t;
def dnsNameToLabel(name):
out = ""
name = name.split(".")
for part in name:
out += chr(len(part)) + part
return out
def dnsFormatQuery(query, qclass, qtype):
header = DNSQueryHeader()
header.dns_id = 0 # FIXME: id = 0
header.dns_rd = 1 # don't know why the original code didn't request recursion for non SOA requests
header.dns_qr = 0 # query
header.dns_opcode = 0 # standard query
header.dns_qdcount = 1 # single query
qlabel = dnsNameToLabel(query)
if not qlabel:
return ""
out = header.pack() + qlabel
out += chr(qtype >> 8)
out += chr(qtype & 0xff)
out += chr(qclass >> 8)
out += chr(qclass & 0xff)
return out
def dnsParseLabel(label, base):
# returns (output, rest)
if not label:
return ("", None)
update = 1
rest = label
output = ""
skip = 0
try:
while ord(rest[0]):
if ord(rest[0]) & 0xc0:
rest = base[((ord(rest[0]) & 0x3f) << 8) + ord(rest[1]):]
if update:
skip += 2
update = 0
continue
output += rest[1:ord(rest[0]) + 1] + "."
if update:
skip += ord(rest[0]) + 1
rest = rest[ord(rest[0]) + 1:]
except IndexError:
return ("", None)
return (label[skip+update:], output)
def dnsParseA(data, base):
rdata = DNSRData()
if len(data) < 4:
rdata.address = 0
return None
rdata.address = (ord(data[0])<<24) | (ord(data[1])<<16) | (ord(data[2])<<8) | (ord(data[3])<<0)
if DEBUG_DNSCLIENT:
print "A = %d.%d.%d.%d." % (ord(data[0]), ord(data[1]), ord(data[2]), ord(data[3]))
return rdata
def dnsParseText(data):
if len(data) < 1:
return ("", None)
tlen = ord(data[0])
if len(data) < tlen + 1:
return ("", None)
return (data[tlen+1:], data[1:tlen+1])
def dnsParseNS(data, base):
rdata = DNSRData()
(rest, rdata.nsdname) = dnsParseLabel(data, base)
if DEBUG_DNSCLIENT:
print "NS DNAME = \"%s\"." % (rdata.nsdname)
return rdata
def dnsParseCNAME(data, base):
rdata = DNSRData()
(rest, rdata.cname) = dnsParseLabel(data, base)
if DEBUG_DNSCLIENT:
print "CNAME = \"%s\"." % (rdata.cname)
return rdata
def dnsParseSOA(data, base):
rdata = DNSRData()
format = "!IIIII"
(rest, rdata.mname) = dnsParseLabel(data, base)
if rdata.mname is None:
return None
(rest, rdata.rname) = dnsParseLabel(rest, base)
if rdata.rname is None:
return None
if len(rest) < struct.calcsize(format):
return None
(rdata.serial, rdata.refresh, rdata.retry, rdata.expire,
rdata.minimum) = struct.unpack(format, rest[:struct.calcsize(format)])
if DEBUG_DNSCLIENT:
print "SOA(mname) = \"%s\"." % rdata.mname
print "SOA(rname) = \"%s\"." % rdata.rname
print "SOA(serial) = %d." % rdata.serial
print "SOA(refresh) = %d." % rdata.refresh
print "SOA(retry) = %d." % rdata.retry
print "SOA(expire) = %d." % rdata.expire
print "SOA(minimum) = %d." % rdata.minimum
return rdata
def dnsParseNULL(data, base):
# um, yeah
return None
def dnsParseWKS(data, base):
return None
def dnsParseHINFO(data, base):
rdata = DNSRData()
(rest, rdata.cpu) = dnsParseText(data)
if rest:
(rest, rdata.os) = dnsParseText(rest)
if DEBUG_DNSCLIENT:
print "HINFO(cpu) = \"%s\"." % rdata.cpu
print "HINFO(os) = \"%s\"." % rdata.os
return rdata
def dnsParseMX(data, base):
rdata = DNSRData()
if len(data) < 2:
return None
rdata.preference = (ord(data[0]) << 8) | ord(data[1])
(rest, rdata.exchange) = dnsParseLabel(data[2:], base)
if DEBUG_DNSCLIENT:
print "MX(exchanger) = \"%s\"." % rdata.exchange
print "MX(preference) = %d." % rdata.preference
return rdata
def dnsParseTXT(data, base):
rdata = DNSRData()
(rest, rdata.data) = dnsParseText(data)
if DEBUG_DNSCLIENT:
print "TXT = \"%s\"." % rdata.data
return rdata
def dnsParsePTR(data, base):
rdata = DNSRData()
(rest, rdata.ptrdname) = dnsParseLabel(data, base)
if DEBUG_DNSCLIENT:
print "PTR = \"%s\"." % rdata.ptrdname
def dnsParseSRV(data, base):
rdata = DNSRData()
format = "!HHH"
flen = struct.calcsize(format)
if len(data) < flen:
return None
(rdata.priority, rdata.weight, rdata.port) = struct.unpack(format, data[:flen])
(rest, rdata.server) = dnsParseLabel(data[flen:], base)
if DEBUG_DNSCLIENT:
print "SRV(server) = \"%s\"." % rdata.server
print "SRV(weight) = %d." % rdata.weight
print "SRV(priority) = %d." % rdata.priority
print "SRV(port) = %d." % rdata.port
return rdata
def dnsParseResults(results):
try:
header = unpackQueryHeader(results)
except struct.error:
return []
if header.dns_qr != 1: # should be a response
return []
if header.dns_rcode != 0: # should be no error
return []
rest = results[header.size():]
rrlist = []
for i in xrange(header.dns_qdcount):
if not rest:
return []
rr = DNSResult()
(rest, label) = dnsParseLabel(rest, results)
if label is None:
return []
if len(rest) < rr.qsize():
return []
rr.qunpack(rest)
rest = rest[rr.qsize():]
if DEBUG_DNSCLIENT:
print "Queried for '%s', class = %d, type = %d." % (label,
rr.dns_class, rr.dns_type)
for i in xrange(header.dns_ancount + header.dns_nscount + header.dns_arcount):
(rest, label) = dnsParseLabel(rest, results)
if label is None:
return []
rr = DNSResult()
rr.dns_name = label
if len(rest) < rr.size():
return []
rr.unpack(rest)
rest = rest[rr.size():]
if DEBUG_DNSCLIENT:
print "Answer %d for '%s', class = %d, type = %d, ttl = %d." % (i,
rr.dns_name, rr.dns_class, rr.dns_type,
rr.dns_ttl)
if len(rest) < rr.dns_rlength:
if DEBUG_DNSCLIENT:
print "Answer too short."
return []
fmap = { DNS_T_A: dnsParseA, DNS_T_NS: dnsParseNS,
DNS_T_CNAME: dnsParseCNAME, DNS_T_SOA: dnsParseSOA,
DNS_T_NULL: dnsParseNULL, DNS_T_WKS: dnsParseWKS,
DNS_T_PTR: dnsParsePTR, DNS_T_HINFO: dnsParseHINFO,
DNS_T_MX: dnsParseMX, DNS_T_TXT: dnsParseTXT,
DNS_T_SRV: dnsParseSRV}
if not rr.dns_type in fmap:
if DEBUG_DNSCLIENT:
print "Don't know how to parse RR type %d!" % rr.dns_type
else:
rr.rdata = fmap[rr.dns_type](rest[:rr.dns_rlength], results)
rest = rest[rr.dns_rlength:]
rrlist += [rr]
if not rrlist:
rrlist = [rr]
return rrlist
def query(query, qclass, qtype):
qdata = dnsFormatQuery(query, qclass, qtype)
if not qdata:
return []
answer = acutil.res_send(qdata)
if not answer:
return []
return dnsParseResults(answer)
if __name__ == '__main__':
DEBUG_DNSCLIENT = True
print "Sending query."
rr = query(len(sys.argv) > 1 and sys.argv[1] or "devserv.devel.redhat.com.",
DNS_C_IN, DNS_T_ANY)
sys.exit(0)