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Add -m to force cache-miss measurement in dnseval (Closes #41)

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Using `-m` causes dnseval to add a random hostname prefix to the given
domain name (format is "_dnseval_RANDOM_."). This will cause NXDOMAIN
and the query fails, but we do measure the response time anyway.
This commit is contained in:
Babak Farrokhi 2018-01-23 15:20:36 +03:30
parent 8283f4dbc2
commit 8a9acd9100
Signed by: farrokhi
GPG Key ID: 6B267AD85D632E9A
1 changed files with 56 additions and 25 deletions
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81
dnseval.py
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@ -33,6 +33,8 @@ import signal
import socket import socket
import sys import sys
import time import time
import random
import string
from statistics import stdev from statistics import stdev
import dns.rdatatype import dns.rdatatype
@ -67,15 +69,16 @@ def usage():
print("""%s version %s print("""%s version %s
usage: %s [-h] [-f server-list] [-c count] [-t type] [-w wait] hostname usage: %s [-h] [-f server-list] [-c count] [-t type] [-w wait] hostname
-h --help show this help -h --help Show this help
-f --file dns server list to use (default: system resolvers) -f --file DNS server list to use (default: system resolvers)
-c --count number of requests to send (default: 10) -c --count Number of requests to send (default: 10)
-w --wait maximum wait time for a reply (default: 2) -m --cache-miss Force cache miss measurement by prepending a random hostname
-t --type DNS request record type (default: A) -w --wait Maximum wait time for a reply (default: 2)
-T --tcp Use TCP instead of UDP -t --type DNS request record type (default: A)
-e --edns Disable EDNS0 (Default: Enabled) -T --tcp Use TCP instead of UDP
-C --color Print colorful output -e --edns Disable EDNS0 (Default: Enabled)
-v --verbose Print actual dns response -C --color Print colorful output
-v --verbose Print actual dns response
""" % (__progname__, __version__, __progname__)) """ % (__progname__, __version__, __progname__))
sys.exit() sys.exit()
@ -137,7 +140,13 @@ def flags_to_text(flags):
return ' '.join(text_flags) return ' '.join(text_flags)
def dnsping(host, server, dnsrecord, timeout, count, use_tcp=False, use_edns=False): def random_string(min_length=5, max_length=10):
char_set = string.ascii_letters + string.digits
length = random.randint(min_length, max_length)
return ''.join(map(lambda unused: random.choice(char_set), range(length)))
def dnsping(host, server, dnsrecord, timeout, count, use_tcp=False, use_edns=False, force_miss=False):
resolver = dns.resolver.Resolver() resolver = dns.resolver.Resolver()
resolver.nameservers = [server] resolver.nameservers = [server]
resolver.timeout = timeout resolver.timeout = timeout
@ -156,12 +165,25 @@ def dnsping(host, server, dnsrecord, timeout, count, use_tcp=False, use_edns=Fal
if shutdown: # user pressed CTRL+C if shutdown: # user pressed CTRL+C
break break
try: try:
answers = resolver.query(host, dnsrecord, tcp=use_tcp, if force_miss:
fqdn = "_dnseval_%s_.%s" % (random_string(), host)
print(fqdn)
else:
fqdn = host
stime = time.perf_counter()
answers = resolver.query(fqdn, dnsrecord, tcp=use_tcp,
raise_on_no_answer=False) # todo: response validation in future raise_on_no_answer=False) # todo: response validation in future
except (dns.resolver.NoNameservers, dns.resolver.NoAnswer): except (dns.resolver.NoNameservers, dns.resolver.NoAnswer):
break break
except dns.resolver.Timeout: except dns.resolver.Timeout:
pass pass
except dns.resolver.NXDOMAIN:
etime = time.perf_counter()
if force_miss:
elapsed = (etime - stime) * 1000 # convert to milliseconds
response_times.append(elapsed)
else: else:
elapsed = answers.response.time * 1000 # convert to milliseconds elapsed = answers.response.time * 1000 # convert to milliseconds
response_times.append(elapsed) response_times.append(elapsed)
@ -210,13 +232,15 @@ def main():
fromfile = False fromfile = False
use_tcp = False use_tcp = False
use_edns = True use_edns = True
force_miss = False
verbose = False verbose = False
color_mode = False color_mode = False
hostname = 'wikipedia.org' hostname = 'wikipedia.org'
try: try:
opts, args = getopt.getopt(sys.argv[1:], "hf:c:t:w:TevC", opts, args = getopt.getopt(sys.argv[1:], "hf:c:t:w:TevCm",
["help", "file=", "count=", "type=", "wait=", "tcp", "edns", "verbose", "color"]) ["help", "file=", "count=", "type=", "wait=", "tcp", "edns", "verbose", "color",
"force-miss"])
except getopt.GetoptError as err: except getopt.GetoptError as err:
print(err) print(err)
usage() usage()
@ -236,6 +260,8 @@ def main():
fromfile = True fromfile = True
elif o in ("-w", "--wait"): elif o in ("-w", "--wait"):
waittime = int(a) waittime = int(a)
elif o in ("-m", "--cache-miss"):
force_miss = True
elif o in ("-t", "--type"): elif o in ("-t", "--type"):
dnsrecord = a dnsrecord = a
elif o in ("-T", "--tcp"): elif o in ("-T", "--tcp"):
@ -282,25 +308,29 @@ def main():
ipaddress.ip_address(server) ipaddress.ip_address(server)
except ValueError: # so it is not a valid IPv4 or IPv6 address, so try to resolve host name except ValueError: # so it is not a valid IPv4 or IPv6 address, so try to resolve host name
try: try:
s = socket.getaddrinfo(server, port=None)[1][4][0] resolver = socket.getaddrinfo(server, port=None)[1][4][0]
except OSError: except OSError:
print('Error: cannot resolve hostname:', server) print('Error: cannot resolve hostname:', server)
s = None resolver = None
except: except:
pass pass
else: else:
s = server resolver = server
if not s: if not resolver:
continue continue
try: try:
(s, r_avg, r_min, r_max, r_stddev, r_lost_percent, flags, ttl, answers) = dnsping(hostname, s, (resolver, r_avg, r_min, r_max, r_stddev, r_lost_percent, flags, ttl, answers) = dnsping(
dnsrecord, hostname,
waittime, resolver,
count, dnsrecord,
use_tcp=use_tcp, waittime,
use_edns=use_edns) count,
use_tcp=use_tcp,
use_edns=use_edns,
force_miss=force_miss
)
except dns.resolver.NXDOMAIN: except dns.resolver.NXDOMAIN:
print('%-15s NXDOMAIN' % server) print('%-15s NXDOMAIN' % server)
continue continue
@ -308,7 +338,7 @@ def main():
print('%s: %s' % (server, e)) print('%s: %s' % (server, e))
continue continue
s = server.ljust(width + 1) resolver = server.ljust(width + 1)
text_flags = flags_to_text(flags) text_flags = flags_to_text(flags)
s_ttl = str(ttl) s_ttl = str(ttl)
@ -320,7 +350,8 @@ def main():
else: else:
l_color = color.N l_color = color.N
print("%s %-8.3f %-8.3f %-8.3f %-8.3f %s%%%-3d%s %-8s %21s" % ( 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) resolver, 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'): if verbose and hasattr(answers, 'response'):
ans_index = 1 ans_index = 1
for answer in answers.response.answer: for answer in answers.response.answer: