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dnseval.py
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dnseval.py
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#!/usr/bin/env python3
#
# Copyright (c) 2016, Babak Farrokhi
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import os
import getopt
import ipaddress
import signal
import socket
import sys
import time
from statistics import stdev
import dns.rdatatype
import dns.resolver
__author__ = 'Babak Farrokhi (babak@farrokhi.net)'
__license__ = 'BSD'
__version__ = "1.6.3"
__progname__ = os.path.basename(sys.argv[0])
shutdown = False
resolvers = dns.resolver.get_default_resolver().nameservers
class Colors(object):
N = '\033[m' # native
R = '\033[31m' # red
G = '\033[32m' # green
O = '\033[33m' # orange
B = '\033[34m' # blue
def __init__(self, mode):
if not mode:
self.N = ''
self.R = ''
self.G = ''
self.O = ''
self.B = ''
def usage():
print("""%s version %s
usage: %s [-h] [-f server-list] [-c count] [-t type] [-w wait] hostname
-h --help show this help
-f --file dns server list to use (default: system resolvers)
-c --count number of requests to send (default: 10)
-w --wait maximum wait time for a reply (default: 2)
-t --type DNS request record type (default: A)
-T --tcp Use TCP instead of UDP
-e --edns Disable EDNS0 (Default: Enabled)
-C --color Print colorful output
-v --verbose Print actual dns response
""" % (__progname__, __version__, __progname__))
sys.exit()
def signal_handler(sig, frame):
global shutdown
if shutdown: # pressed twice, so exit immediately
sys.exit(0)
shutdown = True # pressed once, exit gracefully
def maxlen(names):
sn = sorted(names, key=len)
return len(sn[-1])
def _order_flags(table):
return sorted(table.items(), reverse=True)
def flags_to_text(flags):
# Standard DNS flags
QR = 0x8000
AA = 0x0400
TC = 0x0200
RD = 0x0100
RA = 0x0080
AD = 0x0020
CD = 0x0010
# EDNS flags
DO = 0x8000
_by_text = {
'QR': QR,
'AA': AA,
'TC': TC,
'RD': RD,
'RA': RA,
'AD': AD,
'CD': CD
}
_by_value = dict([(y, x) for x, y in _by_text.items()])
_flags_order = _order_flags(_by_value)
_by_value = dict([(y, x) for x, y in _by_text.items()])
order = sorted(_by_value.items(), reverse=True)
text_flags = []
for k, v in order:
if flags & k != 0:
text_flags.append(v)
else:
text_flags.append('--')
return ' '.join(text_flags)
def dnsping(host, server, dnsrecord, timeout, count, use_tcp=False, use_edns=False):
resolver = dns.resolver.Resolver()
resolver.nameservers = [server]
resolver.timeout = timeout
resolver.lifetime = timeout
resolver.retry_servfail = 0
flags = 0
ttl = None
answers = None
if use_edns:
resolver.use_edns(edns=0, payload=8192, ednsflags=dns.flags.edns_from_text('DO'))
response_times = []
i = 0
for i in range(count):
if shutdown: # user pressed CTRL+C
break
try:
stime = time.perf_counter()
answers = resolver.query(host, dnsrecord, tcp=use_tcp,
raise_on_no_answer=False) # todo: response validation in future
etime = time.perf_counter()
except (dns.resolver.NoNameservers, dns.resolver.NoAnswer):
break
except dns.resolver.Timeout:
pass
else:
elapsed = (etime - stime) * 1000 # convert to milliseconds
response_times.append(elapsed)
r_sent = i + 1
r_received = len(response_times)
r_lost = r_sent - r_received
r_lost_percent = (100 * r_lost) / r_sent
if response_times:
r_min = min(response_times)
r_max = max(response_times)
r_avg = sum(response_times) / r_received
if len(response_times) > 1:
r_stddev = stdev(response_times)
else:
r_stddev = 0
else:
r_min = 0
r_max = 0
r_avg = 0
r_stddev = 0
if answers is not None:
flags = answers.response.flags
if len(answers.response.answer) > 0:
ttl = answers.response.answer[0].ttl
return server, r_avg, r_min, r_max, r_stddev, r_lost_percent, flags, ttl, answers
def main():
try:
signal.signal(signal.SIGTSTP, signal.SIG_IGN) # ignore CTRL+Z
signal.signal(signal.SIGINT, signal_handler) # catch CTRL+C
except AttributeError: # Some systems (e.g. Windows) may not support all signals
pass
if len(sys.argv) == 1:
usage()
# defaults
dnsrecord = 'A'
count = 10
waittime = 2
inputfilename = None
fromfile = False
use_tcp = False
use_edns = True
verbose = False
color_mode = False
hostname = 'wikipedia.org'
try:
opts, args = getopt.getopt(sys.argv[1:], "hf:c:t:w:TevC",
["help", "file=", "count=", "type=", "wait=", "tcp", "edns", "verbose", "color"])
except getopt.GetoptError as err:
print(err)
usage()
if args and len(args) == 1:
hostname = args[0]
else:
usage()
for o, a in opts:
if o in ("-h", "--help"):
usage()
elif o in ("-c", "--count"):
count = int(a)
elif o in ("-f", "--file"):
inputfilename = a
fromfile = True
elif o in ("-w", "--wait"):
waittime = int(a)
elif o in ("-t", "--type"):
dnsrecord = a
elif o in ("-T", "--tcp"):
use_tcp = True
elif o in ("-e", "--edns"):
use_edns = False
elif o in ("-C", "--color"):
color_mode = True
elif o in ("-v", "--verbose"):
verbose = True
else:
print("Invalid option: %s" % o)
usage()
color = Colors(color_mode)
try:
if fromfile:
with open(inputfilename, 'rt') as flist:
f = flist.read().splitlines()
else:
f = resolvers
if len(f) == 0:
print("No nameserver specified")
f = [name.strip() for name in f]
width = maxlen(f)
blanks = (width - 5) * ' '
print('server ', blanks, ' avg(ms) min(ms) max(ms) stddev(ms) lost(%) ttl flags')
print((93 + width) * '-')
for server in f:
# check if we have a valid dns server address
if server.lstrip() == '': # deal with empty lines
continue
server = server.replace(' ', '')
try:
ipaddress.ip_address(server)
except ValueError: # so it is not a valid IPv4 or IPv6 address, so try to resolve host name
try:
s = socket.getaddrinfo(server, port=None)[1][4][0]
except OSError:
print('Error: cannot resolve hostname:', server)
s = None
except:
pass
else:
s = server
if not s:
continue
try:
(s, r_avg, r_min, r_max, r_stddev, r_lost_percent, flags, ttl, answers) = dnsping(hostname, s,
dnsrecord,
waittime,
count,
use_tcp=use_tcp,
use_edns=use_edns)
except dns.resolver.NXDOMAIN:
print('%-15s NXDOMAIN' % server)
continue
except Exception as e:
print('%s: %s' % (server, e))
continue
s = server.ljust(width + 1)
text_flags = flags_to_text(flags)
s_ttl = str(ttl)
if s_ttl == "None":
s_ttl = "N/A"
if r_lost_percent > 0:
l_color = color.O
else:
l_color = color.N
print("%s %-8.3f %-8.3f %-8.3f %-8.3f %s%%%-3d%s %-8s %21s" % (
s, r_avg, r_min, r_max, r_stddev, l_color, r_lost_percent, color.N, s_ttl, text_flags), flush=True)
if verbose and hasattr(answers, 'response'):
ans_index = 1
for answer in answers.response.answer:
print("Answer %d [ %s%s%s ]" % (ans_index, color.G, answer, color.N))
ans_index += 1
print("")
except Exception as e:
print('%s: %s' % (server, e))
sys.exit(1)
if __name__ == '__main__':
main()