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267b03c0 FT |
1 | ;;;; DNS implementation for COMMON-NET |
2 | ||
3 | (in-package :common-net) | |
4 | ||
5 | (defstruct dns-packet | |
6 | (txid (random 65536) :type (unsigned-byte 16)) | |
7 | (is-response nil) | |
8 | (opcode :query :type (member :query :iquery :status)) | |
9 | (authoritative nil) | |
10 | (truncated nil) | |
11 | (recurse nil) | |
12 | (will-recurse nil) | |
13 | (resp-code :success :type (member :success :format-error :server-failure :name-error :not-implemented :refused)) | |
14 | (queries '() :type list) | |
15 | (answers '() :type list) | |
16 | (authority '() :type list) | |
17 | (additional '() :type list)) | |
18 | ||
19 | (defclass resource-query () | |
20 | ((name :initarg :name) | |
21 | (type :initarg :type))) | |
22 | ||
23 | (defclass resource-record () | |
24 | ((name :initarg :name) | |
25 | (ttl :initarg :ttl))) | |
26 | ||
27 | (defvar *rr-coding-types* '()) | |
28 | ||
29 | (defmacro define-rr-type (name class type slots) | |
30 | (let ((format (mapcar #'(lambda (slot) | |
31 | (list* (if (listp (car slot)) | |
32 | (caar slot) | |
33 | (car slot)) | |
34 | (cdr slot))) | |
35 | slots)) | |
28d289c5 FT |
36 | (slot-desc (mapcar #'(lambda (slot) |
37 | (let ((name (car slot))) | |
38 | `(,name :initarg ,(intern (symbol-name name) (find-package :keyword))))) slots))) | |
267b03c0 FT |
39 | `(progn |
40 | (defclass ,name (resource-record) ,slot-desc) | |
41 | (setf *rr-coding-types* (cons '(,name (,class ,type) ,format) | |
42 | (remove ',name *rr-coding-types* :key #'car)))))) | |
43 | ||
44 | (define-rr-type a-record #x1 #x1 | |
45 | ((address ipv4-address))) | |
46 | (define-rr-type ns-record #x1 #x2 | |
47 | ((ns-name domain-name))) | |
48 | (define-rr-type cname-record #x1 #x5 | |
49 | ((cname domain-name))) | |
50 | (define-rr-type soa-record #x1 #x6 | |
51 | ((mname domain-name) | |
52 | (rname domain-name) | |
53 | (serial uint-32) | |
54 | (refresh uint-32) | |
55 | (retry uint-32) | |
56 | (expire uint-32))) | |
57 | (define-rr-type ptr-record #x1 #xc | |
58 | ((pointed domain-name))) | |
59 | (define-rr-type mx-record #x1 #xf | |
60 | ((prio uint-16) | |
61 | (mail-host domain-name))) | |
62 | (define-rr-type txt-record #x1 #x10 | |
63 | ((text text))) | |
64 | (define-rr-type aaaa-record #x1 #x1c | |
65 | ((address ipv6-address))) | |
66 | (define-rr-type srv-record #x1 #x21 | |
67 | ((prio uint-16) | |
68 | (weigth uint-16) | |
69 | (port uint-16) | |
70 | (host-name domain-name))) | |
71 | ||
72 | ;;; Packet decoding logic | |
73 | ||
74 | (defstruct dns-decode-state | |
75 | (packet nil :type (array (unsigned-byte 8))) | |
76 | (pos 0 :type (mod 65536)) | |
77 | (prev-names '() :type list)) | |
78 | ||
79 | (define-condition dns-error (error) ()) | |
80 | (define-condition dns-decode-error (dns-error) | |
81 | ((packet :initarg :packet))) | |
82 | (define-condition simple-dns-decode-error (dns-decode-error simple-error) ()) | |
83 | ||
84 | (defun simple-dns-decode-error (packet format &rest args) | |
85 | (error 'simple-dns-decode-error :packet packet :format-control format :format-argument args)) | |
86 | ||
87 | (defun decode-uint-8 (buf) | |
88 | (declare (type dns-decode-state buf)) | |
89 | (with-slots (packet pos) buf | |
90 | (when (< (- (length packet) pos) 1) | |
91 | (simple-dns-decode-error buf "DNS packet is too short (wanted a 8-bit number).")) | |
92 | (prog1 (aref packet pos) | |
93 | (incf pos)))) | |
94 | ||
95 | (defun decode-uint-16 (buf) | |
96 | (declare (type dns-decode-state buf)) | |
97 | (with-slots (packet pos) buf | |
98 | (when (< (- (length packet) pos) 2) | |
99 | (simple-dns-decode-error buf "DNS packet is too short (wanted a 16-bit number).")) | |
100 | (prog1 | |
101 | (+ (* (aref packet pos) 256) | |
102 | (aref packet (1+ pos))) | |
103 | (incf pos 2)))) | |
104 | ||
105 | (defun decode-uint-32 (buf) | |
106 | (declare (type dns-decode-state buf)) | |
107 | (with-slots (packet pos) buf | |
108 | (when (< (- (length packet) pos) 4) | |
109 | (simple-dns-decode-error buf "DNS packet is too short (wanted a 32-bit number).")) | |
110 | (prog1 | |
111 | (+ (* (aref packet pos) #x1000000) | |
112 | (* (aref packet (+ pos 1)) #x10000) | |
113 | (* (aref packet (+ pos 2)) #x100) | |
114 | (aref packet (+ pos 3))) | |
426521e7 | 115 | (incf pos 4)))) |
267b03c0 FT |
116 | |
117 | (defun decode-domain-name (buf) | |
118 | (declare (type dns-decode-state buf)) | |
426521e7 FT |
119 | (labels ((decode-label () |
120 | (let* ((orig-off (dns-decode-state-pos buf)) | |
121 | (len (decode-uint-8 buf))) | |
122 | (case (ldb (byte 2 6) len) | |
123 | ((0) | |
124 | (if (zerop len) | |
125 | '() | |
126 | (with-slots (packet pos) buf | |
127 | (let* ((label (prog1 | |
128 | (handler-bind | |
129 | ((charcode:coding-error | |
130 | (lambda (c) | |
131 | (declare (ignore c)) | |
132 | (simple-dns-decode-error buf "DNS label was not ASCII.")))) | |
133 | (charcode:decode-string (subseq packet | |
134 | pos (+ pos len)) | |
135 | :ascii)) | |
136 | (incf pos len))) | |
137 | (decoded (append (list label) (decode-label)))) | |
138 | (push (cons orig-off decoded) (slot-value buf 'prev-names)) | |
139 | decoded)))) | |
d2505410 | 140 | ((3) (let* ((offset (+ (* 256 (ldb (byte 6 0) len)) |
426521e7 FT |
141 | (decode-uint-8 buf))) |
142 | (prev (assoc offset (dns-decode-state-prev-names buf)))) | |
143 | (unless prev | |
144 | (simple-dns-decode-error buf "Domain name label pointed to non-label position.")) | |
145 | (cdr prev))) | |
146 | (t (simple-dns-decode-error buf "Illegal DNS label flags: ~D" (ldb (byte 2 6) len))))))) | |
147 | (decode-label))) | |
267b03c0 FT |
148 | |
149 | (defun decode-dns-query (buf) | |
150 | (declare (type dns-decode-state buf)) | |
151 | (let* ((name (decode-domain-name buf)) | |
152 | (type (decode-uint-16 buf)) | |
153 | (class (decode-uint-16 buf)) | |
154 | (desc (find (list class type) *rr-coding-types* :key 'second :test 'equal))) | |
155 | (if desc | |
156 | (make-instance 'resource-query :name name :type (first desc)) | |
157 | (progn (warn "Unknown DNS RR type: ~D, ~D" class type) | |
158 | nil)))) | |
159 | ||
160 | (defun decode-dns-record (buf) | |
161 | (declare (type dns-decode-state buf)) | |
162 | (let* ((name (decode-domain-name buf)) | |
163 | (type (decode-uint-16 buf)) | |
164 | (class (decode-uint-16 buf)) | |
165 | (ttl (decode-uint-32 buf)) | |
166 | (dlen (decode-uint-16 buf)) | |
167 | (desc (find (list class type) *rr-coding-types* :key 'second :test 'equal))) | |
168 | (when (< (length (dns-decode-state-packet buf)) | |
169 | (+ (dns-decode-state-pos buf) dlen)) | |
170 | (simple-dns-decode-error buf "Not enough data left in DNS packet to decode indicated RR data length.")) | |
171 | (if desc | |
172 | (let ((orig-off (dns-decode-state-pos buf)) | |
173 | (rr (make-instance (first desc) | |
174 | :name name | |
175 | :ttl ttl))) | |
176 | (dolist (slot-desc (third desc)) | |
177 | (destructuring-bind (slot-name type) slot-desc | |
178 | (setf (slot-value rr slot-name) | |
179 | (with-slots (packet pos) buf | |
180 | (ecase type | |
181 | ((uint-16) (decode-uint-16 buf)) | |
182 | ((uint-32) (decode-uint-32 buf)) | |
183 | ((domain-name) (decode-domain-name buf)) | |
184 | ((text) | |
185 | (let ((len (decode-uint-8 buf))) | |
186 | (prog1 (subseq packet pos (+ pos len)) | |
187 | (incf pos len)))) | |
188 | ((ipv4-address) | |
189 | (prog1 (make-instance 'ipv4-host-address :host-bytes (subseq packet pos (+ pos 4))) | |
190 | (incf pos 4))) | |
191 | ((ipv6-address) | |
192 | (prog1 (make-instance 'ipv6-host-address :host-bytes (subseq packet pos (+ pos 16))) | |
193 | (incf pos 16)))))))) | |
194 | (unless (= (dns-decode-state-pos buf) (+ orig-off dlen)) | |
195 | (simple-dns-decode-error buf "DNS RR data length did not match up with actual decoded data.")) | |
196 | rr) | |
197 | (progn (warn "Unknown DNS RR type: ~D, ~D" class type) | |
198 | (incf (dns-decode-state-pos buf) dlen) | |
199 | nil)))) | |
200 | ||
201 | (defun decode-dns-packet (buf) | |
202 | (declare (type dns-decode-state buf)) | |
203 | (let* ((txid (decode-uint-16 buf)) | |
204 | (flags (decode-uint-16 buf)) | |
205 | (qnum (decode-uint-16 buf)) | |
206 | (ansnum (decode-uint-16 buf)) | |
207 | (autnum (decode-uint-16 buf)) | |
208 | (auxnum (decode-uint-16 buf)) | |
209 | (packet (make-dns-packet :txid txid | |
210 | :is-response (ldb-test (byte 1 15) flags) | |
211 | :opcode (case (ldb (byte 4 11) flags) | |
212 | ((0) :query) | |
213 | ((1) :iquery) | |
214 | ((2) :status) | |
215 | (t (simple-dns-decode-error buf "Unknown DNS opcode: ~D" (ldb (byte 4 11) flags)))) | |
216 | :authoritative (ldb-test (byte 1 10) flags) | |
217 | :truncated (ldb-test (byte 1 9) flags) | |
218 | :recurse (ldb-test (byte 1 8) flags) | |
219 | :will-recurse (ldb-test (byte 1 7) flags) | |
220 | :resp-code (case (ldb (byte 4 0) flags) | |
221 | ((0) :success) | |
222 | ((1) :format-error) | |
223 | ((2) :server-failure) | |
224 | ((3) :name-error) | |
225 | ((4) :not-implemented) | |
226 | ((5) :refused) | |
227 | (t (simple-dns-decode-error buf "Unknown DNS response code: ~D" (ldb (byte 4 0) flags))))))) | |
228 | (with-slots (queries answers authority additional) packet | |
229 | (dotimes (i qnum) | |
230 | (setf queries (append queries (list (decode-dns-query buf))))) | |
231 | (dotimes (i ansnum) | |
232 | (setf answers (append answers (list (decode-dns-record buf))))) | |
233 | (dotimes (i autnum) | |
234 | (setf authority (append authority (list (decode-dns-record buf))))) | |
235 | (dotimes (i auxnum) | |
236 | (setf additional (append additional (list (decode-dns-record buf)))))) | |
237 | packet)) | |
238 | ||
239 | (defun dns-decode (packet) | |
240 | (decode-dns-packet (make-dns-decode-state :packet packet))) | |
241 | ||
242 | ;;; Packet encoding logic | |
243 | ||
244 | (defstruct dns-encode-state | |
245 | (packet-buf (make-array '(512) :element-type '(unsigned-byte 8) :adjustable t :fill-pointer 0) :type (array (unsigned-byte 8))) | |
246 | (prev-names '() :type list)) | |
247 | ||
248 | (defun encode-uint-8 (buf num) | |
249 | (declare (type dns-encode-state buf) | |
250 | (type (unsigned-byte 8) num)) | |
251 | (with-slots (packet-buf) buf | |
252 | (vector-push-extend num packet-buf))) | |
253 | ||
254 | (defun encode-uint-16 (buf num) | |
255 | (declare (type dns-encode-state buf) | |
256 | (type (unsigned-byte 16) num)) | |
257 | (with-slots (packet-buf) buf | |
258 | (vector-push-extend (ldb (byte 8 8) num) packet-buf) | |
259 | (vector-push-extend (ldb (byte 8 0) num) packet-buf))) | |
260 | ||
261 | (defun encode-uint-32 (buf num) | |
262 | (declare (type dns-encode-state buf) | |
263 | (type (unsigned-byte 32) num)) | |
264 | (with-slots (packet-buf) buf | |
265 | (vector-push-extend (ldb (byte 8 24) num) packet-buf) | |
266 | (vector-push-extend (ldb (byte 8 16) num) packet-buf) | |
267 | (vector-push-extend (ldb (byte 8 8) num) packet-buf) | |
268 | (vector-push-extend (ldb (byte 8 0) num) packet-buf))) | |
269 | ||
270 | (defun encode-bytes (buf bytes) | |
271 | (declare (type dns-encode-state buf) | |
272 | (type (array (unsigned-byte 8)) bytes)) | |
273 | (with-slots (packet-buf) buf | |
274 | (dotimes (i (length bytes) (values)) | |
275 | (vector-push-extend (elt bytes i) packet-buf)))) | |
276 | ||
277 | (defun encode-domain-name (buf name) | |
278 | (declare (type dns-encode-state buf) | |
279 | (type list name)) | |
280 | (with-slots (packet-buf prev-names) buf | |
281 | (labels ((encode-label (name) | |
282 | (let ((prev (find name prev-names :key 'first :test 'equal))) | |
283 | (cond ((null name) | |
284 | (encode-uint-8 buf 0)) | |
285 | (prev | |
286 | (encode-uint-16 buf (+ #xc000 (cdr prev)))) | |
287 | (t | |
288 | (when (< (length packet-buf) 16384) | |
289 | (push (cons name (length packet-buf)) prev-names)) | |
290 | (let ((encoded (charcode:encode-string (car name) :ascii))) | |
291 | (unless (< (length encoded) 64) | |
292 | (error "DNS labels cannot exceed 63 octets in length: ~S" (car name))) | |
293 | (encode-uint-8 buf (length encoded)) | |
294 | (encode-bytes buf encoded)) | |
295 | (encode-label (cdr name))))))) | |
296 | (encode-label name)))) | |
297 | ||
298 | (defun encode-dns-query (buf query) | |
299 | (declare (type dns-encode-state buf) | |
300 | (type resource-query query)) | |
301 | (let ((desc (find (slot-value query 'type) *rr-coding-types* :key 'first))) | |
302 | (encode-domain-name buf (slot-value query 'name)) | |
303 | (encode-uint-16 buf (second (second desc))) | |
304 | (encode-uint-16 buf (first (second desc))))) | |
305 | ||
306 | (defun encode-dns-record (buf record) | |
307 | (declare (type dns-encode-state buf) | |
308 | (type resource-record record)) | |
309 | (let ((desc (find (class-name (class-of record)) *rr-coding-types* :key 'first))) | |
310 | (encode-domain-name buf (slot-value record 'name)) | |
311 | (encode-uint-16 buf (second (second desc))) | |
312 | (encode-uint-16 buf (first (second desc))) | |
313 | (encode-uint-32 buf (slot-value record 'ttl)) | |
314 | (with-slots (packet-buf) buf | |
315 | (let ((orig-off (length packet-buf))) | |
316 | (encode-uint-16 buf 0) | |
317 | (dolist (slot-desc (third desc)) | |
318 | (destructuring-bind (slot-name type) slot-desc | |
319 | (let ((val (slot-value record slot-name))) | |
320 | (ecase type | |
321 | ((uint-16) (encode-uint-16 buf val)) | |
322 | ((uint-32) (encode-uint-32 buf val)) | |
323 | ((domain-name) (encode-domain-name buf val)) | |
324 | ((text) (let ((data (etypecase val | |
325 | (string (charcode:encode-string val :ascii)) | |
326 | ((array (unsigned-byte 8)) val)))) | |
327 | (unless (< (length data) 256) | |
328 | (error "DNS text data length cannot exceed 255 octets.")) | |
329 | (encode-uint-8 buf (length data)) | |
330 | (encode-bytes buf data))) | |
331 | ((ipv4-address) | |
332 | (check-type val ipv4-host-address) | |
333 | (encode-bytes buf (slot-value val 'host-bytes))) | |
334 | ((ipv6-address) | |
335 | (check-type val ipv6-host-address) | |
336 | (encode-bytes buf (slot-value val 'host-bytes))))))) | |
337 | (let ((dlen (- (length packet-buf) orig-off))) | |
338 | (setf (aref packet-buf orig-off) (ldb (byte 8 8) dlen) | |
339 | (aref packet-buf (1+ orig-off)) (ldb (byte 8 0) dlen))))))) | |
340 | ||
341 | (defun encode-dns-packet (buf packet) | |
342 | (declare (type dns-encode-state buf) | |
343 | (type dns-packet packet)) | |
344 | (with-slots (txid is-response opcode authoritative truncated | |
345 | recurse will-recurse resp-code | |
346 | queries answers authority additional) packet | |
347 | (encode-uint-16 buf txid) | |
348 | (let ((flags 0)) | |
349 | (setf (ldb (byte 1 15) flags) (if is-response 1 0) | |
350 | (ldb (byte 4 11) flags) (ecase opcode | |
351 | ((:query) 0) | |
352 | ((:iquery) 1) | |
353 | ((:status) 2)) | |
354 | (ldb (byte 1 10) flags) (if authoritative 1 0) | |
355 | (ldb (byte 1 9) flags) (if truncated 1 0) | |
356 | (ldb (byte 1 8) flags) (if recurse 1 0) | |
357 | (ldb (byte 1 7) flags) (if will-recurse 1 0) | |
358 | (ldb (byte 4 0) flags) (ecase resp-code | |
359 | ((:success) 0) | |
360 | ((:format-error) 1) | |
361 | ((:server-failure) 2) | |
362 | ((:name-error) 3) | |
363 | ((:not-implemented) 4) | |
364 | ((:refused) 5))) | |
365 | (encode-uint-16 buf flags)) | |
366 | (encode-uint-16 buf (length queries)) | |
367 | (encode-uint-16 buf (length answers)) | |
368 | (encode-uint-16 buf (length authority)) | |
369 | (encode-uint-16 buf (length additional)) | |
370 | (dolist (query queries) | |
371 | (encode-dns-query buf query)) | |
372 | (dolist (rr answers) | |
373 | (encode-dns-record buf rr)) | |
374 | (dolist (rr authority) | |
375 | (encode-dns-record buf rr)) | |
376 | (dolist (rr additional) | |
377 | (encode-dns-record buf rr))) | |
378 | (values)) | |
379 | ||
380 | (defun dns-encode (packet) | |
381 | (check-type packet dns-packet) | |
382 | (let ((buf (make-dns-encode-state))) | |
383 | (encode-dns-packet buf packet) | |
384 | (slot-value buf 'packet-buf))) | |
b466cd48 FT |
385 | |
386 | ;;; DN format | |
387 | ||
388 | (defun parse-domain-name (name) | |
389 | (declare (type string name)) | |
390 | (let ((l '()) | |
391 | (p 0)) | |
392 | (loop (let ((p2 (position #\. name :start p))) | |
393 | (if p2 | |
394 | (if (= p2 (1- (length name))) | |
395 | (return (values l t)) | |
396 | (setf l (append l (list (subseq name p p2))) | |
397 | p (1+ p2))) | |
398 | (return (values (append l (list (subseq name p))) nil))))))) | |
399 | ||
400 | (defun unparse-domain-name (name) | |
401 | (declare (type list name)) | |
402 | (let ((buf nil)) | |
403 | (dolist (label name buf) | |
404 | (setf buf (if buf | |
405 | (concatenate 'string buf "." label) | |
406 | label))))) | |
407 | ||
0818ef99 FT |
408 | ;;; Basic communication |
409 | ||
d62b2326 FT |
410 | (define-condition name-server-timeout (dns-error) |
411 | ((server :initarg :server))) | |
412 | ||
0818ef99 FT |
413 | (defun dns-do-request (server packet) |
414 | (declare (type address server) | |
415 | (type dns-packet packet)) | |
416 | (with-connection (sk server) | |
417 | (socket-send sk (dns-encode packet)) | |
418 | (loop | |
419 | (let ((resp (dns-decode (socket-recv sk)))) | |
420 | (when (= (dns-packet-txid resp) | |
421 | (dns-packet-txid packet)) | |
422 | (return resp)))))) | |
423 | ||
424 | (defun dns-std-request (queries &key (txid (random 65536)) (recurse t)) | |
425 | (let ((qlist (map 'list #'(lambda (o) | |
426 | (let ((name (first o)) | |
427 | (type (second o))) | |
428 | (make-instance 'resource-query | |
429 | :name (etypecase name | |
430 | (string (parse-domain-name name)) | |
431 | (list name)) | |
432 | :type type))) | |
433 | queries))) | |
434 | (make-dns-packet :txid txid | |
435 | :recurse recurse | |
436 | :queries qlist))) | |
437 | ||
28d289c5 FT |
438 | ;;; RR caching |
439 | ||
440 | (defstruct domain-cache-entry | |
d62b2326 | 441 | (expire nil :type (or number null)) |
28d289c5 FT |
442 | (records '() :type list)) |
443 | ||
d62b2326 FT |
444 | (defun domain-cache-key (name type) |
445 | (list name (etypecase type | |
446 | (symbol type) | |
447 | (resource-record (class-name (class-of type)))))) | |
448 | ||
449 | (defun domain-cache-key-rr (record) | |
450 | (declare (type resource-record record)) | |
451 | (list (slot-value record 'name) (class-name (class-of record)))) | |
452 | ||
28d289c5 | 453 | (defun domain-cache-get-entry (cache name type &optional create) |
d62b2326 | 454 | (let* ((key (domain-cache-key name type)) |
28d289c5 | 455 | (cur (gethash key cache))) |
d62b2326 FT |
456 | (when (and cur (or (eq create :clear) |
457 | (let ((expire (domain-cache-entry-expire cur))) | |
458 | (and expire | |
459 | (> (/ (get-internal-real-time) internal-time-units-per-second) | |
460 | expire))))) | |
461 | (remhash key cache) | |
462 | (setf cur nil)) | |
28d289c5 FT |
463 | (cond (cur cur) |
464 | (create | |
465 | (setf (gethash key cache) (make-domain-cache-entry)))))) | |
466 | ||
467 | (defun domain-cache-put (cache record) | |
468 | (with-slots (name ttl) record | |
469 | (let ((entry (domain-cache-get-entry cache name record t))) | |
470 | (push record (domain-cache-entry-records entry))))) | |
471 | ||
d62b2326 FT |
472 | (defun dns-cache-records (cache records) |
473 | (loop (unless records (return)) | |
474 | (let* ((key (domain-cache-key-rr (car records))) | |
475 | (matching (remove key records :test-not 'equal :key #'domain-cache-key-rr)) | |
476 | (ttl (block no-expire | |
477 | (+ (/ (get-internal-real-time) internal-time-units-per-second) | |
478 | (apply 'min (mapcar #'(lambda (rr) | |
479 | (with-slots (ttl) rr | |
480 | (if ttl ttl (return-from no-expire nil)))) | |
481 | matching))))) | |
482 | (entry (make-domain-cache-entry :expire ttl :records matching))) | |
483 | (setf (gethash key cache) entry | |
484 | records (set-difference records matching))))) | |
485 | ||
486 | (defun dns-cache-response (cache packet) | |
487 | (let ((records (append (dns-packet-answers packet) | |
488 | (dns-packet-authority packet) | |
489 | (dns-packet-additional packet)))) | |
490 | (flet ((on-root (rr) | |
491 | (equal (slot-value rr 'name) '()))) | |
492 | (when (some #'on-root records) | |
493 | (warn "DNS packet purports to contain RRs on the root zone.") | |
494 | (setf records (delete-if #'on-root records)))) | |
495 | (when (dns-packet-authoritative packet) | |
496 | (dolist (rq (dns-packet-queries packet)) | |
497 | (with-slots (name type) rq | |
498 | (unless (equal name '()) | |
499 | (let ((key (domain-cache-key name type))) | |
500 | (unless (find key records :test 'equal :key #'domain-cache-key-rr) | |
501 | (let ((entry (domain-cache-get-entry cache name type :clear))) | |
502 | (setf (domain-cache-entry-expire entry) | |
503 | (+ (/ (get-internal-real-time) internal-time-units-per-second) | |
504 | 60))))))))) ; XXX: Or something. It needs | |
505 | ; to last for the query in | |
506 | ; progress, at least. One | |
507 | ; should probably look at an | |
508 | ; SOA RR, if there is one. | |
509 | (dns-cache-records cache records))) | |
510 | ||
28d289c5 FT |
511 | (defun make-domain-cache () |
512 | (let ((table (make-hash-table :test 'equal))) | |
513 | (dolist (server (labels ((ipv4 (address) | |
514 | (make-instance 'ipv4-host-address :host-string address))) | |
515 | `(("a.root-servers.net" ,(ipv4 "198.41.0.4")) | |
516 | ("b.root-servers.net" ,(ipv4 "192.228.79.201")) | |
517 | ("c.root-servers.net" ,(ipv4 "192.33.4.12")) | |
518 | ("d.root-servers.net" ,(ipv4 "128.8.10.90")) | |
519 | ("e.root-servers.net" ,(ipv4 "192.203.230.10")) | |
520 | ("f.root-servers.net" ,(ipv4 "192.5.5.241")) | |
521 | ("g.root-servers.net" ,(ipv4 "192.112.36.4")) | |
522 | ("h.root-servers.net" ,(ipv4 "128.63.2.53")) | |
523 | ("i.root-servers.net" ,(ipv4 "192.36.148.17")) | |
524 | ("j.root-servers.net" ,(ipv4 "192.58.128.30")) | |
525 | ("k.root-servers.net" ,(ipv4 "193.0.14.129")) | |
526 | ("l.root-servers.net" ,(ipv4 "199.7.83.42")) | |
527 | ("m.root-servers.net" ,(ipv4 "202.12.27.33"))))) | |
528 | (let ((parsed (parse-domain-name (first server)))) | |
529 | (domain-cache-put table (make-instance 'ns-record :name '() :ttl nil :ns-name parsed)) | |
d62b2326 FT |
530 | ;; Ensure that the cache is initialized at least with empty |
531 | ;; lists, so that the resolver doesn't try to resolve the root | |
532 | ;; servers. | |
533 | (domain-cache-get-entry table parsed 'a-record t) | |
534 | (domain-cache-get-entry table parsed 'aaaa-record t) | |
535 | ||
28d289c5 FT |
536 | (dolist (address (cdr server)) |
537 | (domain-cache-put table (etypecase address | |
538 | (ipv4-host-address (make-instance 'a-record :name parsed :ttl nil :address address))))))) | |
539 | table)) | |
540 | ||
541 | ;;; Resolver | |
542 | ||
543 | (defstruct resolver-config | |
544 | (cache (make-domain-cache)) | |
545 | (default-domains '() :type list) | |
546 | (help-servers '() :type list)) | |
547 | ||
548 | (defun initialize-default-resolver () | |
549 | #+unix (with-open-file (s #p"/etc/resolv.conf" :if-does-not-exist nil) | |
550 | (when s | |
551 | (let ((cfg (make-resolver-config))) | |
552 | (labels ((whitespace-p (char) | |
553 | (declare (type character char)) | |
554 | (or (char= char #\space) | |
555 | (char= char #\tab))) | |
556 | (split-line (line) | |
557 | (let ((l '()) | |
558 | (p 0)) | |
559 | (loop (let* ((p1 (or (position-if-not #'whitespace-p line :start p) | |
560 | (return l))) | |
561 | (p2 (position-if #'whitespace-p line :start p1))) | |
562 | (if p2 | |
563 | (setf l (append l (list (subseq line p1 p2))) | |
564 | p p2) | |
565 | (progn (setf l (append l (list (subseq line p1 p2)))) | |
566 | (return l)))))))) | |
567 | (let ((domain nil) | |
568 | (search '())) | |
569 | (loop (let ((line (read-line s nil nil))) | |
570 | (unless line (return)) | |
571 | (let ((line (split-line line))) | |
572 | (when line | |
573 | (cond ((equal (car line) "nameserver") | |
574 | (push (make-instance 'ipv4-address :host-string (second line)) | |
575 | (resolver-config-help-servers cfg))) | |
576 | ((equal (car line) "search") | |
577 | (setf search (append search (cdr line)))) | |
578 | ((equal (car line) "domain") | |
579 | (setf domain (second line)))))))) | |
580 | (setf (resolver-config-default-domains cfg) | |
581 | (or search (and domain (list domain))))) | |
582 | cfg)))) | |
583 | #-unix nil) | |
584 | ||
d62b2326 | 585 | (defvar *dns-resolver-config* (initialize-default-resolver)) |
28d289c5 | 586 | |
d62b2326 | 587 | (defgeneric dns-server-address-for-record (record)) |
6c36ab4a FT |
588 | (defmethod dns-server-address-for-record ((record a-record)) |
589 | (make-instance 'udp4-address | |
590 | :host-address (slot-value record 'address) | |
591 | :port 53)) | |
592 | (defmethod dns-server-address-for-record ((record aaaa-record)) | |
593 | (make-instance 'udp6-address | |
594 | :host-address (slot-value record 'address) | |
595 | :port 53)) | |
596 | ||
597 | (define-condition dns-resolver-condition (condition) | |
598 | ((query-name :initarg :query-name) | |
599 | (query-type :initarg :query-type) | |
600 | (config :initarg :config))) | |
601 | ||
602 | (define-condition dns-resolver-error (dns-error dns-resolver-condition) ()) | |
603 | (define-condition domain-not-found-error (dns-resolver-error) () | |
604 | (:report (lambda (c s) | |
605 | (with-slots (query-name) c | |
606 | (format s "No name servers found for domain name ~A." query-name))))) | |
607 | (define-condition dns-name-error (dns-error dns-resolver-condition) () | |
608 | (:report (lambda (c s) | |
609 | (with-slots (query-name) c | |
610 | (format s "The domain name ~A does not exist." query-name))))) | |
611 | ||
612 | (define-condition dns-resolver-querying (dns-resolver-condition) | |
613 | ((server :initarg :server))) | |
614 | ||
615 | (define-condition dns-resolver-got-resp (dns-resolver-condition) | |
616 | ((server :initarg :server) | |
617 | (response :initarg :response))) | |
618 | ||
619 | (define-condition dns-resolver-help (dns-resolver-condition) ()) | |
620 | (define-condition dns-resolver-recursing (dns-resolver-condition) ()) | |
621 | ||
622 | (define-condition dns-resolver-following-cname (dns-resolver-condition) | |
623 | ((cname-rr :initarg :cname-rr))) | |
624 | ||
625 | (defun dns-resolve-name (name types &key (require-all t) (config *dns-resolver-config*)) | |
626 | (let ((name (etypecase name | |
627 | (list name) | |
628 | (string (parse-domain-name name)))) | |
629 | (types (etypecase types | |
630 | (list types) | |
631 | (symbol (list types)))) | |
632 | (cache (resolver-config-cache config))) | |
633 | (flet ((check-cache () | |
634 | (let ((cn-entry (domain-cache-get-entry cache name 'cname-record))) | |
635 | (when (and cn-entry (domain-cache-entry-records cn-entry)) | |
636 | (let ((record (car (domain-cache-entry-records cn-entry)))) | |
637 | (signal 'dns-resolver-following-cname :cname-rr record | |
638 | :query-name (unparse-domain-name name) :query-type types | |
639 | :config config) | |
640 | (return-from dns-resolve-name | |
641 | (dns-resolve-name (slot-value record 'cname) types :config config))))) | |
642 | (block skip | |
643 | (let ((records '()) | |
644 | (got-some nil)) | |
645 | (dolist (type types) | |
646 | (let ((entry (domain-cache-get-entry cache name type))) | |
647 | (cond (entry | |
648 | (setf records (append records (domain-cache-entry-records entry)) | |
649 | got-some t)) | |
650 | (require-all | |
651 | (return-from skip))))) | |
652 | (when got-some | |
653 | (return-from dns-resolve-name (values records name)))))) | |
654 | (nearest-known-servers (name) | |
655 | (labels ((check1 (name) | |
656 | (let ((entry (domain-cache-get-entry cache name 'ns-record))) | |
657 | (cond ((and entry (domain-cache-entry-records entry)) | |
658 | (values (domain-cache-entry-records entry) name)) | |
659 | (name (check1 (cdr name))) | |
660 | (t (values '() name)))))) | |
661 | (check1 name))) | |
662 | (do-request (server) | |
663 | (signal 'dns-resolver-querying :server server | |
664 | :query-name (unparse-domain-name name) :query-type types | |
665 | :config config) | |
666 | (handler-case | |
667 | (let ((resp (dns-do-request (udp-address-for server 53) | |
668 | (dns-std-request (mapcar #'(lambda (type) | |
669 | `(,name ,type)) | |
670 | types))))) | |
671 | (signal 'dns-resolver-got-resp :server server :response resp | |
672 | :query-name (unparse-domain-name name) :query-type types | |
673 | :config config) | |
674 | (dns-cache-response cache resp) | |
675 | (with-slots (resp-code) resp | |
676 | (when (eq (dns-packet-resp-code resp) :name-error) | |
677 | (error 'dns-name-error :query-name (unparse-domain-name name) :query-type types | |
678 | :config config)) | |
679 | (eq resp-code :success))) | |
680 | (name-server-timeout () nil)))) | |
681 | (check-cache) | |
682 | (signal 'dns-resolver-help :query-name (unparse-domain-name name) :query-type types | |
683 | :config config) | |
684 | (dolist (help-server (resolver-config-help-servers config)) | |
685 | (do-request help-server) | |
686 | (check-cache)) | |
687 | (signal 'dns-resolver-recursing :query-name (unparse-domain-name name) :query-type types | |
688 | :config config) | |
689 | (let ((checked-domains '())) | |
690 | (loop (multiple-value-bind (servers domain) | |
691 | (nearest-known-servers name) | |
692 | (unless servers | |
693 | (error 'domain-not-found-error :query-name (unparse-domain-name name) :query-type types | |
694 | :config config)) | |
695 | (if (find domain checked-domains :test 'equal) | |
696 | (error 'domain-not-found-error :query-name (unparse-domain-name name) :query-type types | |
697 | :config config) | |
698 | (push domain checked-domains)) | |
699 | (macrolet ((dolist-random ((var list) &body body) | |
700 | (let ((copy (gensym "COPY"))) | |
701 | `(let ((,copy ,list)) | |
702 | (loop (unless ,copy (return)) | |
703 | (let ((,var (elt ,list (random (length ,list))))) | |
704 | (setf ,copy (remove ,var ,copy)) | |
705 | ,@body)))))) | |
706 | (block found-server | |
707 | (dolist-random (record servers) | |
708 | (let* ((server (slot-value record 'ns-name))) | |
709 | (dolist-random (record (handler-case | |
710 | (dns-resolve-name server '(a-record aaaa-record) :require-all nil :config config) | |
711 | (dns-resolver-error () '()))) | |
712 | (when (do-request (dns-server-address-for-record record)) | |
713 | (return-from found-server)))))) | |
714 | (check-cache)))))))) | |
28d289c5 | 715 | |
b466cd48 FT |
716 | ;;; Misc. |
717 | ||
718 | (defmethod print-object ((q resource-query) stream) | |
719 | (with-slots (name type) q | |
720 | (if *print-readably* | |
721 | (format stream "~A: ~A" type (unparse-domain-name name)) | |
722 | (format stream "#<~S ~S ~S>" 'resource-query type (unparse-domain-name name))))) | |
723 |