HCoop / bpt / emacs.git / blame
| Commit | Line | Data |
|---|---|---|
| fb18c032 GM |
1 | ;;; dns.el --- Domain Name Service lookups |
| 2 | ||
| ba318903 | 3 | ;; Copyright (C) 2002-2014 Free Software Foundation, Inc. |
| fb18c032 GM |
4 | |
| 5 | ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org> | |
| e7b94bbb | 6 | ;; Keywords: network comm |
| fb18c032 GM |
7 | |
| 8 | ;; This file is part of GNU Emacs. | |
| 9 | ||
| 874a927a | 10 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
| fb18c032 | 11 | ;; it under the terms of the GNU General Public License as published by |
| 874a927a GM |
12 | ;; the Free Software Foundation, either version 3 of the License, or |
| 13 | ;; (at your option) any later version. | |
| fb18c032 GM |
14 | |
| 15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
| 16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 874a927a | 17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| fb18c032 GM |
18 | ;; GNU General Public License for more details. |
| 19 | ||
| 20 | ;; You should have received a copy of the GNU General Public License | |
| 874a927a | 21 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
| fb18c032 GM |
22 | |
| 23 | ;;; Commentary: | |
| 24 | ||
| 25 | ;;; Code: | |
| 26 | ||
| fb18c032 GM |
27 | (defvar dns-timeout 5 |
| 28 | "How many seconds to wait when doing DNS queries.") | |
| 29 | ||
| 30 | (defvar dns-servers nil | |
| e3e955fe MB |
31 | "List of DNS servers to query. |
| 32 | If nil, /etc/resolv.conf and nslookup will be consulted.") | |
| fb18c032 | 33 | |
| 7a31038f G |
34 | (defvar dns-servers-valid-for-interfaces nil |
| 35 | "The return value of `network-interface-list' when `dns-servers' was set. | |
| 36 | If the set of network interfaces and/or their IP addresses | |
| 37 | change, then presumably the list of DNS servers needs to be | |
| 38 | updated. Set this variable to t to disable the check.") | |
| 39 | ||
| fb18c032 GM |
40 | ;;; Internal code: |
| 41 | ||
| 42 | (defvar dns-query-types | |
| 43 | '((A 1) | |
| 44 | (NS 2) | |
| 45 | (MD 3) | |
| 46 | (MF 4) | |
| 47 | (CNAME 5) | |
| 48 | (SOA 6) | |
| 49 | (MB 7) | |
| 50 | (MG 8) | |
| 51 | (MR 9) | |
| 52 | (NULL 10) | |
| 53 | (WKS 11) | |
| 54 | (PTR 12) | |
| 55 | (HINFO 13) | |
| 56 | (MINFO 14) | |
| 57 | (MX 15) | |
| 58 | (TXT 16) | |
| 59 | (AAAA 28) ; RFC3596 | |
| 60 | (SRV 33) ; RFC2782 | |
| 61 | (AXFR 252) | |
| 62 | (MAILB 253) | |
| 63 | (MAILA 254) | |
| 64 | (* 255)) | |
| 65 | "Names of query types and their values.") | |
| 66 | ||
| 67 | (defvar dns-classes | |
| 68 | '((IN 1) | |
| 69 | (CS 2) | |
| 70 | (CH 3) | |
| 71 | (HS 4)) | |
| 72 | "Classes of queries.") | |
| 73 | ||
| 74 | (defun dns-write-bytes (value &optional length) | |
| 75 | (let (bytes) | |
| 76 | (dotimes (i (or length 1)) | |
| 77 | (push (% value 256) bytes) | |
| 78 | (setq value (/ value 256))) | |
| 79 | (dolist (byte bytes) | |
| 80 | (insert byte)))) | |
| 81 | ||
| 82 | (defun dns-read-bytes (length) | |
| 83 | (let ((value 0)) | |
| 84 | (dotimes (i length) | |
| 85 | (setq value (logior (* value 256) (following-char))) | |
| 86 | (forward-char 1)) | |
| 87 | value)) | |
| 88 | ||
| 89 | (defun dns-get (type spec) | |
| 90 | (cadr (assq type spec))) | |
| 91 | ||
| 92 | (defun dns-inverse-get (value spec) | |
| 93 | (let ((found nil)) | |
| 94 | (while (and (not found) | |
| 95 | spec) | |
| 96 | (if (eq value (cadr (car spec))) | |
| 97 | (setq found (caar spec)) | |
| 98 | (pop spec))) | |
| 99 | found)) | |
| 100 | ||
| 101 | (defun dns-write-name (name) | |
| 102 | (dolist (part (split-string name "\\.")) | |
| 103 | (dns-write-bytes (length part)) | |
| 104 | (insert part)) | |
| 105 | (dns-write-bytes 0)) | |
| 106 | ||
| 107 | (defun dns-read-string-name (string buffer) | |
| eb21f2ff | 108 | (with-temp-buffer |
| 765d4319 | 109 | (unless (featurep 'xemacs) (set-buffer-multibyte nil)) |
| eb21f2ff SM |
110 | (insert string) |
| 111 | (goto-char (point-min)) | |
| 112 | (dns-read-name buffer))) | |
| fb18c032 GM |
113 | |
| 114 | (defun dns-read-name (&optional buffer) | |
| 115 | (let ((ended nil) | |
| 116 | (name nil) | |
| 117 | length) | |
| 118 | (while (not ended) | |
| 119 | (setq length (dns-read-bytes 1)) | |
| 120 | (if (= 192 (logand length (lsh 3 6))) | |
| 121 | (let ((offset (+ (* (logand 63 length) 256) | |
| 122 | (dns-read-bytes 1)))) | |
| 123 | (save-excursion | |
| 124 | (when buffer | |
| 125 | (set-buffer buffer)) | |
| 126 | (goto-char (1+ offset)) | |
| 127 | (setq ended (dns-read-name buffer)))) | |
| 128 | (if (zerop length) | |
| 129 | (setq ended t) | |
| 130 | (push (buffer-substring (point) | |
| 131 | (progn (forward-char length) (point))) | |
| 132 | name)))) | |
| 133 | (if (stringp ended) | |
| 134 | (if (null name) | |
| 135 | ended | |
| 136 | (concat (mapconcat 'identity (nreverse name) ".") "." ended)) | |
| 137 | (mapconcat 'identity (nreverse name) ".")))) | |
| 138 | ||
| 139 | (defun dns-write (spec &optional tcp-p) | |
| 140 | "Write a DNS packet according to SPEC. | |
| 141 | If TCP-P, the first two bytes of the package with be the length field." | |
| 142 | (with-temp-buffer | |
| 765d4319 | 143 | (unless (featurep 'xemacs) (set-buffer-multibyte nil)) |
| fb18c032 GM |
144 | (dns-write-bytes (dns-get 'id spec) 2) |
| 145 | (dns-write-bytes | |
| 146 | (logior | |
| 147 | (lsh (if (dns-get 'response-p spec) 1 0) -7) | |
| 148 | (lsh | |
| 149 | (cond | |
| 150 | ((eq (dns-get 'opcode spec) 'query) 0) | |
| 151 | ((eq (dns-get 'opcode spec) 'inverse-query) 1) | |
| 152 | ((eq (dns-get 'opcode spec) 'status) 2) | |
| 153 | (t (error "No such opcode: %s" (dns-get 'opcode spec)))) | |
| 154 | -3) | |
| 155 | (lsh (if (dns-get 'authoritative-p spec) 1 0) -2) | |
| 156 | (lsh (if (dns-get 'truncated-p spec) 1 0) -1) | |
| 157 | (lsh (if (dns-get 'recursion-desired-p spec) 1 0) 0))) | |
| 158 | (dns-write-bytes | |
| c9fc72fa | 159 | (cond |
| fb18c032 GM |
160 | ((eq (dns-get 'response-code spec) 'no-error) 0) |
| 161 | ((eq (dns-get 'response-code spec) 'format-error) 1) | |
| 162 | ((eq (dns-get 'response-code spec) 'server-failure) 2) | |
| 163 | ((eq (dns-get 'response-code spec) 'name-error) 3) | |
| 164 | ((eq (dns-get 'response-code spec) 'not-implemented) 4) | |
| 165 | ((eq (dns-get 'response-code spec) 'refused) 5) | |
| 166 | (t 0))) | |
| 167 | (dns-write-bytes (length (dns-get 'queries spec)) 2) | |
| 168 | (dns-write-bytes (length (dns-get 'answers spec)) 2) | |
| 169 | (dns-write-bytes (length (dns-get 'authorities spec)) 2) | |
| 170 | (dns-write-bytes (length (dns-get 'additionals spec)) 2) | |
| 171 | (dolist (query (dns-get 'queries spec)) | |
| 172 | (dns-write-name (car query)) | |
| 173 | (dns-write-bytes (cadr (assq (or (dns-get 'type query) 'A) | |
| 174 | dns-query-types)) 2) | |
| 175 | (dns-write-bytes (cadr (assq (or (dns-get 'class query) 'IN) | |
| 176 | dns-classes)) 2)) | |
| 177 | (dolist (slot '(answers authorities additionals)) | |
| 178 | (dolist (resource (dns-get slot spec)) | |
| 179 | (dns-write-name (car resource)) | |
| 180 | (dns-write-bytes (cadr (assq (dns-get 'type resource) dns-query-types)) | |
| 181 | 2) | |
| 182 | (dns-write-bytes (cadr (assq (dns-get 'class resource) dns-classes)) | |
| 183 | 2) | |
| 184 | (dns-write-bytes (dns-get 'ttl resource) 4) | |
| 185 | (dns-write-bytes (length (dns-get 'data resource)) 2) | |
| 186 | (insert (dns-get 'data resource)))) | |
| 187 | (when tcp-p | |
| 188 | (goto-char (point-min)) | |
| 189 | (dns-write-bytes (buffer-size) 2)) | |
| 190 | (buffer-string))) | |
| 191 | ||
| 192 | (defun dns-read (packet) | |
| eb21f2ff | 193 | (with-temp-buffer |
| 765d4319 | 194 | (unless (featurep 'xemacs) (set-buffer-multibyte nil)) |
| eb21f2ff SM |
195 | (let ((spec nil) |
| 196 | queries answers authorities additionals) | |
| 197 | (insert packet) | |
| 198 | (goto-char (point-min)) | |
| 199 | (push (list 'id (dns-read-bytes 2)) spec) | |
| 200 | (let ((byte (dns-read-bytes 1))) | |
| 201 | (push (list 'response-p (if (zerop (logand byte (lsh 1 7))) nil t)) | |
| 202 | spec) | |
| 203 | (let ((opcode (logand byte (lsh 7 3)))) | |
| 204 | (push (list 'opcode | |
| 205 | (cond ((eq opcode 0) 'query) | |
| 206 | ((eq opcode 1) 'inverse-query) | |
| 207 | ((eq opcode 2) 'status))) | |
| b544b8e5 | 208 | spec)) |
| eb21f2ff SM |
209 | (push (list 'authoritative-p (if (zerop (logand byte (lsh 1 2))) |
| 210 | nil t)) spec) | |
| 211 | (push (list 'truncated-p (if (zerop (logand byte (lsh 1 2))) nil t)) | |
| 212 | spec) | |
| 213 | (push (list 'recursion-desired-p | |
| 214 | (if (zerop (logand byte (lsh 1 0))) nil t)) spec)) | |
| 215 | (let ((rc (logand (dns-read-bytes 1) 15))) | |
| 216 | (push (list 'response-code | |
| 217 | (cond | |
| 218 | ((eq rc 0) 'no-error) | |
| 219 | ((eq rc 1) 'format-error) | |
| 220 | ((eq rc 2) 'server-failure) | |
| 221 | ((eq rc 3) 'name-error) | |
| 222 | ((eq rc 4) 'not-implemented) | |
| 223 | ((eq rc 5) 'refused))) | |
| 224 | spec)) | |
| 225 | (setq queries (dns-read-bytes 2)) | |
| 226 | (setq answers (dns-read-bytes 2)) | |
| 227 | (setq authorities (dns-read-bytes 2)) | |
| 228 | (setq additionals (dns-read-bytes 2)) | |
| 229 | (let ((qs nil)) | |
| 230 | (dotimes (i queries) | |
| 231 | (push (list (dns-read-name) | |
| 232 | (list 'type (dns-inverse-get (dns-read-bytes 2) | |
| 233 | dns-query-types)) | |
| 234 | (list 'class (dns-inverse-get (dns-read-bytes 2) | |
| 235 | dns-classes))) | |
| 236 | qs)) | |
| 237 | (push (list 'queries qs) spec)) | |
| 238 | (dolist (slot '(answers authorities additionals)) | |
| 239 | (let ((qs nil) | |
| 240 | type) | |
| 241 | (dotimes (i (symbol-value slot)) | |
| b544b8e5 | 242 | (push (list (dns-read-name) |
| eb21f2ff SM |
243 | (list 'type |
| 244 | (setq type (dns-inverse-get (dns-read-bytes 2) | |
| 245 | dns-query-types))) | |
| b544b8e5 | 246 | (list 'class (dns-inverse-get (dns-read-bytes 2) |
| eb21f2ff SM |
247 | dns-classes)) |
| 248 | (list 'ttl (dns-read-bytes 4)) | |
| 249 | (let ((length (dns-read-bytes 2))) | |
| 250 | (list 'data | |
| 251 | (dns-read-type | |
| 252 | (buffer-substring | |
| 253 | (point) | |
| 254 | (progn (forward-char length) (point))) | |
| 255 | type)))) | |
| b544b8e5 | 256 | qs)) |
| eb21f2ff SM |
257 | (push (list slot qs) spec))) |
| 258 | (nreverse spec)))) | |
| fb18c032 GM |
259 | |
| 260 | (defun dns-read-int32 () | |
| 984ef96d LI |
261 | ;; Full 32 bit Integers can't be handled by 32-bit Emacsen. If we |
| 262 | ;; use floats, it works. | |
| fb18c032 GM |
263 | (format "%.0f" (+ (* (dns-read-bytes 1) 16777216.0) |
| 264 | (dns-read-bytes 3)))) | |
| 265 | ||
| 266 | (defun dns-read-type (string type) | |
| 267 | (let ((buffer (current-buffer)) | |
| 268 | (point (point))) | |
| 269 | (prog1 | |
| eb21f2ff | 270 | (with-temp-buffer |
| 765d4319 | 271 | (unless (featurep 'xemacs) (set-buffer-multibyte nil)) |
| eb21f2ff SM |
272 | (insert string) |
| 273 | (goto-char (point-min)) | |
| 274 | (cond | |
| 275 | ((eq type 'A) | |
| 276 | (let ((bytes nil)) | |
| 277 | (dotimes (i 4) | |
| 278 | (push (dns-read-bytes 1) bytes)) | |
| 279 | (mapconcat 'number-to-string (nreverse bytes) "."))) | |
| 280 | ((eq type 'AAAA) | |
| 281 | (let (hextets) | |
| 282 | (dotimes (i 8) | |
| 283 | (push (dns-read-bytes 2) hextets)) | |
| 284 | (mapconcat (lambda (n) (format "%x" n)) | |
| 285 | (nreverse hextets) ":"))) | |
| 286 | ((eq type 'SOA) | |
| 287 | (list (list 'mname (dns-read-name buffer)) | |
| 288 | (list 'rname (dns-read-name buffer)) | |
| 289 | (list 'serial (dns-read-int32)) | |
| 290 | (list 'refresh (dns-read-int32)) | |
| 291 | (list 'retry (dns-read-int32)) | |
| 292 | (list 'expire (dns-read-int32)) | |
| 293 | (list 'minimum (dns-read-int32)))) | |
| 294 | ((eq type 'SRV) | |
| 295 | (list (list 'priority (dns-read-bytes 2)) | |
| 296 | (list 'weight (dns-read-bytes 2)) | |
| 297 | (list 'port (dns-read-bytes 2)) | |
| 298 | (list 'target (dns-read-name buffer)))) | |
| 299 | ((eq type 'MX) | |
| 300 | (cons (dns-read-bytes 2) (dns-read-name buffer))) | |
| 301 | ((or (eq type 'CNAME) (eq type 'NS) (eq type 'PTR)) | |
| 302 | (dns-read-string-name string buffer)) | |
| 303 | (t string))) | |
| fb18c032 GM |
304 | (goto-char point)))) |
| 305 | ||
| 7a31038f G |
306 | (declare-function network-interface-list "process.c") |
| 307 | ||
| 308 | (defun dns-servers-up-to-date-p () | |
| 309 | "Return false if we need to recheck the list of DNS servers." | |
| 310 | (and dns-servers | |
| 311 | (or (eq dns-servers-valid-for-interfaces t) | |
| 312 | ;; `network-interface-list' was introduced in Emacs 22.1. | |
| 313 | (not (fboundp 'network-interface-list)) | |
| 314 | (equal dns-servers-valid-for-interfaces | |
| 315 | (network-interface-list))))) | |
| 316 | ||
| e3e955fe MB |
317 | (defun dns-set-servers () |
| 318 | "Set `dns-servers' to a list of DNS servers or nil if none are found. | |
| 319 | Parses \"/etc/resolv.conf\" or calls \"nslookup\"." | |
| 320 | (or (when (file-exists-p "/etc/resolv.conf") | |
| 321 | (setq dns-servers nil) | |
| 322 | (with-temp-buffer | |
| 323 | (insert-file-contents "/etc/resolv.conf") | |
| 324 | (goto-char (point-min)) | |
| 325 | (while (re-search-forward "^nameserver[\t ]+\\([^ \t\n]+\\)" nil t) | |
| 326 | (push (match-string 1) dns-servers)) | |
| 327 | (setq dns-servers (nreverse dns-servers)))) | |
| 328 | (when (executable-find "nslookup") | |
| 329 | (with-temp-buffer | |
| 330 | (call-process "nslookup" nil t nil "localhost") | |
| 331 | (goto-char (point-min)) | |
| 332 | (re-search-forward | |
| 333 | "^Address:[ \t]*\\([0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+\\)" nil t) | |
| 7a31038f G |
334 | (setq dns-servers (list (match-string 1)))))) |
| 335 | (when (fboundp 'network-interface-list) | |
| 336 | (setq dns-servers-valid-for-interfaces (network-interface-list)))) | |
| fb18c032 GM |
337 | |
| 338 | (defun dns-read-txt (string) | |
| 339 | (if (> (length string) 1) | |
| 340 | (substring string 1) | |
| 341 | string)) | |
| 342 | ||
| 343 | (defun dns-get-txt-answer (answers) | |
| 344 | (let ((result "") | |
| 345 | (do-next nil)) | |
| 346 | (dolist (answer answers) | |
| 347 | (dolist (elem answer) | |
| 348 | (when (consp elem) | |
| 349 | (cond | |
| 350 | ((eq (car elem) 'type) | |
| 351 | (setq do-next (eq (cadr elem) 'TXT))) | |
| 352 | ((eq (car elem) 'data) | |
| 353 | (when do-next | |
| 354 | (setq result (concat result (dns-read-txt (cadr elem)))))))))) | |
| 355 | result)) | |
| 356 | ||
| 357 | ;;; Interface functions. | |
| 358 | (defmacro dns-make-network-process (server) | |
| 359 | (if (featurep 'xemacs) | |
| 360 | `(let ((coding-system-for-read 'binary) | |
| 361 | (coding-system-for-write 'binary)) | |
| 362 | (open-network-stream "dns" (current-buffer) | |
| 363 | ,server "domain" 'udp)) | |
| 364 | `(let ((server ,server) | |
| 365 | (coding-system-for-read 'binary) | |
| 366 | (coding-system-for-write 'binary)) | |
| 367 | (if (fboundp 'make-network-process) | |
| 368 | (make-network-process | |
| 369 | :name "dns" | |
| 370 | :coding 'binary | |
| 371 | :buffer (current-buffer) | |
| 372 | :host server | |
| 373 | :service "domain" | |
| 374 | :type 'datagram) | |
| 375 | ;; Older versions of Emacs doesn't have | |
| 376 | ;; `make-network-process', so we fall back on opening a TCP | |
| 377 | ;; connection to the DNS server. | |
| 378 | (open-network-stream "dns" (current-buffer) server "domain"))))) | |
| 379 | ||
| 380 | (defvar dns-cache (make-vector 4096 0)) | |
| 381 | ||
| e3e955fe | 382 | (defun dns-query-cached (name &optional type fullp reversep) |
| fb18c032 GM |
383 | (let* ((key (format "%s:%s:%s:%s" name type fullp reversep)) |
| 384 | (sym (intern-soft key dns-cache))) | |
| 385 | (if (and sym | |
| 386 | (boundp sym)) | |
| 387 | (symbol-value sym) | |
| e3e955fe | 388 | (let ((result (dns-query name type fullp reversep))) |
| fb18c032 GM |
389 | (set (intern key dns-cache) result) |
| 390 | result)))) | |
| 391 | ||
| e3e955fe MB |
392 | ;; The old names `query-dns' and `query-dns-cached' weren't used in Emacs 23 |
| 393 | ;; yet, so no alias are provided. --rsteib | |
| 394 | ||
| 395 | (defun dns-query (name &optional type fullp reversep) | |
| fb18c032 GM |
396 | "Query a DNS server for NAME of TYPE. |
| 397 | If FULLP, return the entire record returned. | |
| 398 | If REVERSEP, look up an IP address." | |
| 399 | (setq type (or type 'A)) | |
| 7a31038f | 400 | (unless (dns-servers-up-to-date-p) |
| e3e955fe | 401 | (dns-set-servers)) |
| fb18c032 GM |
402 | |
| 403 | (when reversep | |
| 404 | (setq name (concat | |
| 405 | (mapconcat 'identity (nreverse (split-string name "\\.")) ".") | |
| 406 | ".in-addr.arpa") | |
| 407 | type 'PTR)) | |
| 408 | ||
| 409 | (if (not dns-servers) | |
| 410 | (message "No DNS server configuration found") | |
| eb21f2ff | 411 | (with-temp-buffer |
| 765d4319 | 412 | (unless (featurep 'xemacs) (set-buffer-multibyte nil)) |
| eb21f2ff SM |
413 | (let ((process (condition-case () |
| 414 | (dns-make-network-process (car dns-servers)) | |
| 415 | (error | |
| 416 | (message | |
| 417 | "dns: Got an error while trying to talk to %s" | |
| 418 | (car dns-servers)) | |
| 419 | nil))) | |
| 420 | (tcp-p (and (not (fboundp 'make-network-process)) | |
| 421 | (not (featurep 'xemacs)))) | |
| 422 | (step 100) | |
| 423 | (times (* dns-timeout 1000)) | |
| 424 | (id (random 65000))) | |
| 425 | (when process | |
| 426 | (process-send-string | |
| 427 | process | |
| 428 | (dns-write `((id ,id) | |
| 429 | (opcode query) | |
| 430 | (queries ((,name (type ,type)))) | |
| 431 | (recursion-desired-p t)) | |
| 432 | tcp-p)) | |
| 433 | (while (and (zerop (buffer-size)) | |
| 434 | (> times 0)) | |
| 435 | (sit-for (/ step 1000.0)) | |
| 436 | (accept-process-output process 0 step) | |
| 437 | (setq times (- times step))) | |
| 438 | (condition-case nil | |
| 439 | (delete-process process) | |
| 440 | (error nil)) | |
| 441 | (when (and tcp-p | |
| 442 | (>= (buffer-size) 2)) | |
| 443 | (goto-char (point-min)) | |
| 444 | (delete-region (point) (+ (point) 2))) | |
| 445 | (when (and (>= (buffer-size) 2) | |
| 446 | ;; We had a time-out. | |
| 447 | (> times 0)) | |
| 448 | (let ((result (dns-read (buffer-string)))) | |
| 449 | (if fullp | |
| 450 | result | |
| 451 | (let ((answer (car (dns-get 'answers result)))) | |
| 452 | (when (eq type (dns-get 'type answer)) | |
| 453 | (if (eq type 'TXT) | |
| 454 | (dns-get-txt-answer (dns-get 'answers result)) | |
| 455 | (dns-get 'data answer)))))))))))) | |
| fb18c032 GM |
456 | |
| 457 | (provide 'dns) | |
| 458 | ||
| fb18c032 | 459 | ;;; dns.el ends here |