]>
gitweb.michael.orlitzky.com - djbdns-logparse.git/blob - bin/djbdns-logparse.py
3 Convert tinydns and dnscache logs to human-readable form
7 from struct
import pack
9 ## Regular expressions for matching tinydns/dnscache log lines. We
10 ## compile these once here rather than within the corresponding
11 ## matching functions, because the latter get executed repeatedly.
13 # This first pattern is used to match the timestamp format that the
14 # tai64nlocal program produces. It appears in both dnscache and
15 # tinydns lines, after they've been piped through tai64nlocal, of
17 timestamp_pat
= r
'[\d-]+ [\d:\.]+'
19 # The regex to match dnscache log lines.
20 dnscache_log_re
= re
.compile(fr
'({timestamp_pat}) (\w+)(.*)')
22 # The "hex4" pattern matches a string of four hexadecimal digits. This
23 # is used, for example, by tinydns to encode the query type
25 hex4_pat
= r
'[0-9a-f]{4}'
27 # The IP pattern matches a string of either 8 or 32 hexadecimal
28 # characters, which correspond to IPv4 and IPv6 addresses,
29 # respectively, in tinydns logs.
30 ip_pat
= r
'[0-9a-f]{8,32}'
32 # The regex to match tinydns log lines.
33 tinydns_log_re
= re
.compile(
34 rf
'({timestamp_pat}) ({ip_pat}):({hex4_pat}):({hex4_pat}) ([\+\-IC/]) ({hex4_pat}) (.*)'
37 # A dictionary mapping query type identifiers, in decimal, to their
38 # friendly names for tinydns. Reference:
40 # https://en.wikipedia.org/wiki/List_of_DNS_record_types
42 # Note that mapping here is non-exhaustive, and that tinydns will
43 # log responses for record types that it does not know about.
68 # tinydns can drop a query for one of three reasons; this dictionary
69 # maps the symbol that gets logged in each case to a human-readable
70 # reason. We include the "+" case here, indicating that the query was
71 # NOT dropped, to avoid a special case later on when we're formatting
72 # the human-readable output.
82 def convert_ip(ip
: str) -> str:
84 Convert a hex string representing an IP address to
91 The hexadecimal representation of either an IPv4 or an IPv6
97 The usual decimal dotted-quad representation is returned for an
98 IPv4 address. IPv6 addresses are returned almost as-is, but with
99 colons inserted in the appropriate places, between every four
105 >>> convert_ip("7f000001")
107 >>> convert_ip("00000000000000000000ffff7f000001")
108 '0000:0000:0000:0000:0000:ffff:7f00:0001'
111 # IPv4, eg. "7f000001" -> "7f 00 00 01" -> "127.0.0.1"
112 return ".".join(map(str, pack(">L", int(ip
, 16))))
114 # IPv6 is actually simpler -- it's just a string-slicing operation.
115 return ":".join([ip
[(4*i
) : (4*i
+4)] for i
in range(8)])
118 def decode_client(words
: list, i
: int):
120 Helper function to decode the client field in a dnscache log
123 There are two possible formats for the client field,
125 1. clientip:clientport, used by tcpopen/tcpclose entries,
126 2. clientip:clientport:id, used by "query" entries.
132 The ``words`` list (a list of fields) from
133 :func:`handle_dnscache_log`.
136 The index of the client field within ``words``
141 Nothing; the ``i``th entry in the ``words`` list is modified
147 >>> words = ["foo", "bar", "7f000001:9253", "quux"]
148 >>> decode_client(words, 2)
150 ['foo', 'bar', '127.0.0.1:37459', 'quux']
152 >>> words = ["foo", "7f000001:a3db:4fb9", "bar", "quux"]
153 >>> decode_client(words, 1)
155 ['foo', '127.0.0.1:41947 (id 20409)', 'bar', 'quux']
158 chunks
= words
[i
].split(":")
160 ip
= convert_ip(chunks
[0])
161 port
= int(chunks
[1], 16)
162 words
[i
] = f
"{ip}:{port}"
165 # For a "query" entry's clientip:clientport:id field.
166 id = int(chunks
[2], 16)
167 words
[i
] += f
" (id {id})"
169 def decode_ip(words
, i
):
170 words
[i
] = convert_ip(words
[i
])
172 def decode_ttl(words
, i
):
173 words
[i
] = f
"TTL={words[i]}"
175 def decode_serial(words
, i
):
176 serial
= int(words
[i
])
177 words
[i
] = f
"#{serial}"
179 def decode_type(words
, i
):
181 words
[i
] = query_type
.get(int(qt
), qt
)
183 def handle_dnscache_log(line
) -> typing
.Optional
[str]:
185 Handle a single log line if it matches the ``dnscache_log_re`` regex.
191 The log line that might match ``dnscache_log_re``.
196 Either the human-readable string if the log line was handled (that
197 is, if it was really a dnscache log line), or ``None`` if it was
203 >>> line = "2022-09-15 18:37:33.863805500 query 1 7f000001:a3db:4fb9 1 www.example.com."
204 >>> handle_dnscache_log(line)
205 '2022-09-15 18:37:33.863805500 query #1 127.0.0.1:41947 (id 20409) a www.example.com.'
207 >>> line = "2022-09-15 18:37:33.863874500 tx 0 1 www.example.com. . c0a80101"
208 >>> handle_dnscache_log(line)
209 '2022-09-15 18:37:33.863874500 tx g=0 a www.example.com. . 192.168.1.1'
211 >>> line = "2022-09-15 18:37:33.878529500 rr c0a80101 20865 1 www.example.com. 5db8d822"
212 >>> handle_dnscache_log(line)
213 '2022-09-15 18:37:33.878529500 rr 192.168.1.1 TTL=20865 a www.example.com. 93.184.216.34'
215 >>> line = "2022-09-15 18:37:33.878532500 stats 1 43 1 0"
216 >>> handle_dnscache_log(line)
217 '2022-09-15 18:37:33.878532500 stats count=1 motion=43 udp-active=1 tcp-active=0'
219 >>> line = "2022-09-15 18:37:33.878602500 sent 1 49"
220 >>> handle_dnscache_log(line)
221 '2022-09-15 18:37:33.878602500 sent #1 49'
223 >>> line = "this line is nonsense"
224 >>> handle_dnscache_log(line)
227 match
= dnscache_log_re
.match(line
)
231 (timestamp
, event
, data
) = match
.groups()
234 if event
== "cached":
235 if words
[0] not in ("cname", "ns", "nxdomain"):
236 decode_type(words
, 0)
238 elif event
== "drop":
239 decode_serial(words
, 0)
241 elif event
== "lame":
244 elif event
== "nodata":
247 decode_type(words
, 2)
249 elif event
== "nxdomain":
253 elif event
== "query":
254 decode_serial(words
, 0)
255 decode_client(words
, 1)
256 decode_type(words
, 2)
261 if words
[2] not in ("cname", "mx", "ns", "ptr", "soa"):
262 decode_type(words
, 2)
263 if words
[2] == "a": # decode answer to an A query
265 if words
[2] == "txt": # text record
267 if response
.endswith("..."):
269 response
= response
[0:-3]
272 length
= int(response
[0:2], 16)
274 for i
in range(1, len(response
)//2):
275 chars
.append(chr(int(response
[2*i
: (2*i
)+2], 16)))
277 words
[4] = f
"{length}:\"{txt}{ellipsis}\""
279 elif event
== "sent":
280 decode_serial(words
, 0)
282 elif event
== "stats":
283 words
[0] = f
"count={words[0]}"
284 words
[1] = f
"motion={words[1]}"
285 words
[2] = f
"udp-active={words[2]}"
286 words
[3] = f
"tcp-active={words[3]}"
289 words
[0] = f
"g={words[0]}"
290 decode_type(words
, 1)
292 # words[3] = control (domain for which these servers are believed
293 # to be authoritative)
294 for i
in range(4, len(words
)):
297 elif event
in ("tcpopen", "tcpclose"):
298 decode_client(words
, 0)
300 # Reconstitute "data" (i.e. everything after the timestamp and the
301 # event) from "words", which was originally obtained by splitting
303 data
= " ".join(words
)
304 return f
"{timestamp} {event} {data}"
308 def handle_tinydns_log(line
: str) -> typing
.Optional
[str]:
310 Handle a single log line if it matches the ``tinydns_log_re`` regex.
316 The log line that might match ``tinydns_log_re``.
321 Either the human-readable string if the log line was handled (that
322 is, if it was really a tinydns log line), or ``None`` if it was
328 >>> line = "2022-09-14 21:04:40.206516500 7f000001:9d61:be69 - 0001 www.example.com"
329 >>> handle_tinydns_log(line)
330 '2022-09-14 21:04:40.206516500 dropped query (no authority) from 127.0.0.1:40289 (id 48745): a www.example.com'
332 >>> line = "this line is nonsense"
333 >>> handle_tinydns_log(line)
336 match
= tinydns_log_re
.match(line
)
340 (timestamp
, ip
, port
, id, code
, type, name
) = match
.groups()
345 # Convert the "type" field to a human-readable record type name
346 # using the query_type dictionary. If the right name isn't present
347 # in the dictionary, we use the (decimal) type id instead.
348 type = int(type, 16) # "001c" -> 28
349 type = query_type
.get(type, type) # 28 -> "aaaa"
351 line_tpl
= "{timestamp} "
353 reason
= query_drop_reason
[code
]
355 line_tpl
+= "sent response to {ip}:{port} (id {id}): {type} {name}"
357 line_tpl
+= "dropped query ({reason}) from {ip}:{port}"
359 # If the query can actually be parsed, the log line is a
360 # bit more informative than it would have been otherwise.
361 line_tpl
+= " (id {id}): {type} {name}"
363 return line_tpl
.format(timestamp
=timestamp
,
372 def parse_logfile(file : typing
.TextIO
):
374 Process a single log ``file``.
380 An open log file, or stdin.
385 >>> line = "@4000000063227a320c4f3114 7f000001:9d61:be69 - 0001 www.example.com\n"
386 >>> from tempfile import NamedTemporaryFile
387 >>> with NamedTemporaryFile(mode="w", delete=False) as f:
388 ... _ = f.write(line)
389 >>> f = open(f.name, 'r')
391 2022-09-14 21:04:40.206516500 dropped query (no authority) from 127.0.0.1:40289 (id 48745): a www.example.com
393 >>> from os import remove
397 # Open a pipe to tai64nlocal. We'll write lines of our input file
398 # (the log file) to it, and read back the same lines but with
399 # friendly timestamps in them.
400 from subprocess
import Popen
, PIPE
401 tai
= Popen(["tai64nlocal"], stdin
=PIPE
, stdout
=PIPE
, text
=True, bufsize
=0)
404 tai
.stdin
.write(line
)
405 line
= tai
.stdout
.readline()
407 friendly_line
= handle_tinydns_log(line
)
408 if not friendly_line
:
409 friendly_line
= handle_dnscache_log(line
)
410 if not friendly_line
:
417 The entry point to the program.
419 This function is responsible only for parsing any command-line
420 arguments, and then calling :func`parse_logfile` on them.
422 # Create an argument parser using the file's docsctring as its
424 from argparse
import ArgumentParser
, FileType
425 parser
= ArgumentParser(description
= __doc__
)
427 # Parse zero or more positional arguments into a list of
428 # "logfiles". If none are given, read from stdin instead.
429 from sys
import stdin
430 parser
.add_argument("logfiles",
435 help="djbdns logfile to process (default: stdin)")
437 # Warning: argparse automatically opens its file arguments here,
438 # and they only get closed when the program terminates. There's no
439 # real benefit to closing them one-at-a-time after calling
440 # parse_logfile(), because the "scarce" resource of open file
441 # descriptors gets consumed immediately, before any processing has
442 # happened. In other words, if you're going to run out of file
443 # descriptors, it's going to happen right now.
445 # So anyway, don't run this on several million logfiles.
446 args
= parser
.parse_args()
447 for f
in args
.logfiles
:
451 if __name__
== "__main__":