]>
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.
128 We convert each part from hex to decimal, and in the second
129 format, separate the packet id from the client information.
135 The ``words`` list (a list of fields) from
136 :func:`handle_dnscache_log`.
139 The index of the client field within ``words``
144 Nothing; the ``i``th entry in the ``words`` list is modified
150 >>> words = ["foo", "bar", "7f000001:9253", "quux"]
151 >>> decode_client(words, 2)
153 ['foo', 'bar', '127.0.0.1:37459', 'quux']
155 >>> words = ["foo", "7f000001:a3db:4fb9", "bar", "quux"]
156 >>> decode_client(words, 1)
158 ['foo', '127.0.0.1:41947 (id 20409)', 'bar', 'quux']
161 chunks
= words
[i
].split(":")
163 ip
= convert_ip(chunks
[0])
164 port
= int(chunks
[1], 16)
165 words
[i
] = f
"{ip}:{port}"
168 # For a "query" entry's clientip:clientport:id field.
169 id = int(chunks
[2], 16)
170 words
[i
] += f
" (id {id})"
172 def decode_ip(words
: list, i
: int):
174 Helper function to decode the ip field in a dnscache log
177 A single "serverip" field is present in the lame, nodata,
178 nxdomain, and rr entry types. We convert it from hex to decimal.
184 The ``words`` list (a list of fields) from
185 :func:`handle_dnscache_log`.
188 The index of the ip field within ``words``
193 Nothing; the ``i``th entry in the ``words`` list is modified
199 >>> words = ["foo", "bar", "7f000001", "quux"]
200 >>> decode_ip(words, 2)
202 ['foo', 'bar', '127.0.0.1', 'quux']
204 >>> words = ["foo", "00000000000000000000ffff7f000001", "bar", "quux"]
205 >>> decode_ip(words, 1)
207 ['foo', '0000:0000:0000:0000:0000:ffff:7f00:0001', 'bar', 'quux']
209 words
[i
] = convert_ip(words
[i
])
211 def decode_ttl(words
: list, i
: int):
213 Helper function to decode the ttl field in a dnscache log
216 A single "ttl" field is present in the nodata, nxdomain, and
217 rr entry types. We prefix it with "TTL=" so that its meaning
218 is clear in the human-readable logs.
224 The ``words`` list (a list of fields) from
225 :func:`handle_dnscache_log`.
228 The index of the ttl field within ``words``
233 Nothing; the ``i``th entry in the ``words`` list is modified
239 >>> words = ["c0a80101", "20865", "1", "www.example.com.", "5db8d822"]
240 >>> decode_ttl(words, 1)
242 ['c0a80101', 'TTL=20865', '1', 'www.example.com.', '5db8d822']
245 words
[i
] = f
"TTL={words[i]}"
247 def decode_serial(words
: list, i
: int):
248 serial
= int(words
[i
])
249 words
[i
] = f
"#{serial}"
251 def decode_type(words
: list, i
: int):
253 words
[i
] = query_type
.get(int(qt
), qt
)
255 def handle_dnscache_log(line
: str) -> typing
.Optional
[str]:
257 Handle a single log line if it matches the ``dnscache_log_re`` regex.
263 The log line that might match ``dnscache_log_re``.
268 Either the human-readable string if the log line was handled (that
269 is, if it was really a dnscache log line), or ``None`` if it was
275 >>> line = "2022-09-15 18:37:33.863805500 query 1 7f000001:a3db:4fb9 1 www.example.com."
276 >>> handle_dnscache_log(line)
277 '2022-09-15 18:37:33.863805500 query #1 127.0.0.1:41947 (id 20409) a www.example.com.'
279 >>> line = "2022-09-15 18:37:33.863874500 tx 0 1 www.example.com. . c0a80101"
280 >>> handle_dnscache_log(line)
281 '2022-09-15 18:37:33.863874500 tx g=0 a www.example.com. . 192.168.1.1'
283 >>> line = "2022-09-15 18:37:33.878529500 rr c0a80101 20865 1 www.example.com. 5db8d822"
284 >>> handle_dnscache_log(line)
285 '2022-09-15 18:37:33.878529500 rr 192.168.1.1 TTL=20865 a www.example.com. 93.184.216.34'
287 >>> line = "2022-09-15 18:37:33.878532500 stats 1 43 1 0"
288 >>> handle_dnscache_log(line)
289 '2022-09-15 18:37:33.878532500 stats count=1 motion=43 udp-active=1 tcp-active=0'
291 >>> line = "2022-09-15 18:37:33.878602500 sent 1 49"
292 >>> handle_dnscache_log(line)
293 '2022-09-15 18:37:33.878602500 sent #1 49'
295 >>> line = "this line is nonsense"
296 >>> handle_dnscache_log(line)
299 match
= dnscache_log_re
.match(line
)
303 (timestamp
, event
, data
) = match
.groups()
306 if event
== "cached":
307 if words
[0] not in ("cname", "ns", "nxdomain"):
308 decode_type(words
, 0)
310 elif event
== "drop":
311 decode_serial(words
, 0)
313 elif event
== "lame":
316 elif event
== "nodata":
319 decode_type(words
, 2)
321 elif event
== "nxdomain":
325 elif event
== "query":
326 decode_serial(words
, 0)
327 decode_client(words
, 1)
328 decode_type(words
, 2)
333 if words
[2] not in ("cname", "mx", "ns", "ptr", "soa"):
334 decode_type(words
, 2)
335 if words
[2] == "a": # decode answer to an A query
337 if words
[2] == "txt": # text record
339 if response
.endswith("..."):
341 response
= response
[0:-3]
344 length
= int(response
[0:2], 16)
346 for i
in range(1, len(response
)//2):
347 chars
.append(chr(int(response
[2*i
: (2*i
)+2], 16)))
349 words
[4] = f
"{length}:\"{txt}{ellipsis}\""
351 elif event
== "sent":
352 decode_serial(words
, 0)
354 elif event
== "stats":
355 words
[0] = f
"count={words[0]}"
356 words
[1] = f
"motion={words[1]}"
357 words
[2] = f
"udp-active={words[2]}"
358 words
[3] = f
"tcp-active={words[3]}"
361 words
[0] = f
"g={words[0]}"
362 decode_type(words
, 1)
364 # words[3] = control (domain for which these servers are believed
365 # to be authoritative)
366 for i
in range(4, len(words
)):
369 elif event
in ("tcpopen", "tcpclose"):
370 decode_client(words
, 0)
372 # Reconstitute "data" (i.e. everything after the timestamp and the
373 # event) from "words", which was originally obtained by splitting
375 data
= " ".join(words
)
376 return f
"{timestamp} {event} {data}"
380 def handle_tinydns_log(line
: str) -> typing
.Optional
[str]:
382 Handle a single log line if it matches the ``tinydns_log_re`` regex.
388 The log line that might match ``tinydns_log_re``.
393 Either the human-readable string if the log line was handled (that
394 is, if it was really a tinydns log line), or ``None`` if it was
400 >>> line = "2022-09-14 21:04:40.206516500 7f000001:9d61:be69 - 0001 www.example.com"
401 >>> handle_tinydns_log(line)
402 '2022-09-14 21:04:40.206516500 dropped query (no authority) from 127.0.0.1:40289 (id 48745): a www.example.com'
404 >>> line = "this line is nonsense"
405 >>> handle_tinydns_log(line)
408 match
= tinydns_log_re
.match(line
)
412 (timestamp
, ip
, port
, id, code
, type, name
) = match
.groups()
417 # Convert the "type" field to a human-readable record type name
418 # using the query_type dictionary. If the right name isn't present
419 # in the dictionary, we use the (decimal) type id instead.
420 type = int(type, 16) # "001c" -> 28
421 type = query_type
.get(type, type) # 28 -> "aaaa"
423 line_tpl
= "{timestamp} "
425 reason
= query_drop_reason
[code
]
427 line_tpl
+= "sent response to {ip}:{port} (id {id}): {type} {name}"
429 line_tpl
+= "dropped query ({reason}) from {ip}:{port}"
431 # If the query can actually be parsed, the log line is a
432 # bit more informative than it would have been otherwise.
433 line_tpl
+= " (id {id}): {type} {name}"
435 return line_tpl
.format(timestamp
=timestamp
,
444 def parse_logfile(file : typing
.TextIO
):
446 Process a single log ``file``.
452 An open log file, or stdin.
457 >>> line = "@4000000063227a320c4f3114 7f000001:9d61:be69 - 0001 www.example.com\n"
458 >>> from tempfile import NamedTemporaryFile
459 >>> with NamedTemporaryFile(mode="w", delete=False) as f:
460 ... _ = f.write(line)
461 >>> f = open(f.name, 'r')
463 2022-09-14 21:04:40.206516500 dropped query (no authority) from 127.0.0.1:40289 (id 48745): a www.example.com
465 >>> from os import remove
469 # Open a pipe to tai64nlocal. We'll write lines of our input file
470 # (the log file) to it, and read back the same lines but with
471 # friendly timestamps in them.
472 from subprocess
import Popen
, PIPE
473 tai
= Popen(["tai64nlocal"], stdin
=PIPE
, stdout
=PIPE
, text
=True, bufsize
=0)
476 tai
.stdin
.write(line
)
477 line
= tai
.stdout
.readline()
479 friendly_line
= handle_tinydns_log(line
)
480 if not friendly_line
:
481 friendly_line
= handle_dnscache_log(line
)
482 if not friendly_line
:
489 The entry point to the program.
491 This function is responsible only for parsing any command-line
492 arguments, and then calling :func`parse_logfile` on them.
494 # Create an argument parser using the file's docsctring as its
496 from argparse
import ArgumentParser
, FileType
497 parser
= ArgumentParser(description
= __doc__
)
499 # Parse zero or more positional arguments into a list of
500 # "logfiles". If none are given, read from stdin instead.
501 from sys
import stdin
502 parser
.add_argument("logfiles",
507 help="djbdns logfile to process (default: stdin)")
509 # Warning: argparse automatically opens its file arguments here,
510 # and they only get closed when the program terminates. There's no
511 # real benefit to closing them one-at-a-time after calling
512 # parse_logfile(), because the "scarce" resource of open file
513 # descriptors gets consumed immediately, before any processing has
514 # happened. In other words, if you're going to run out of file
515 # descriptors, it's going to happen right now.
517 # So anyway, don't run this on several million logfiles.
518 args
= parser
.parse_args()
519 for f
in args
.logfiles
:
523 if __name__
== "__main__":