;;; dns.el --- Domain Name Service lookups
-;; Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+
+;; Copyright (C) 2002-2015 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
-;; Keywords: network
+;; Keywords: network comm
;; This file is part of GNU Emacs.
-;; GNU Emacs is free software; you can redistribute it and/or modify
+;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation; either version 2, or (at your option)
-;; any later version.
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
-;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
-;; along with GNU Emacs; see the file COPYING. If not, write to the
-;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-;; Boston, MA 02110-1301, USA.
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;; Code:
-(eval-when-compile (require 'cl))
-
-(require 'mm-util)
-
(defvar dns-timeout 5
"How many seconds to wait when doing DNS queries.")
(defvar dns-servers nil
- "Which DNS servers to query.
-If nil, /etc/resolv.conf will be consulted.")
+ "List of DNS servers to query.
+If nil, /etc/resolv.conf and nslookup will be consulted.")
+
+(defvar dns-servers-valid-for-interfaces nil
+ "The return value of `network-interface-list' when `dns-servers' was set.
+If the set of network interfaces and/or their IP addresses
+change, then presumably the list of DNS servers needs to be
+updated. Set this variable to t to disable the check.")
;;; Internal code:
(dns-write-bytes 0))
(defun dns-read-string-name (string buffer)
- (mm-with-unibyte-buffer
+ (with-temp-buffer
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(insert string)
(goto-char (point-min))
(dns-read-name buffer)))
"Write a DNS packet according to SPEC.
If TCP-P, the first two bytes of the package with be the length field."
(with-temp-buffer
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(dns-write-bytes (dns-get 'id spec) 2)
(dns-write-bytes
(logior
(lsh (if (dns-get 'truncated-p spec) 1 0) -1)
(lsh (if (dns-get 'recursion-desired-p spec) 1 0) 0)))
(dns-write-bytes
- (cond
+ (cond
((eq (dns-get 'response-code spec) 'no-error) 0)
((eq (dns-get 'response-code spec) 'format-error) 1)
((eq (dns-get 'response-code spec) 'server-failure) 2)
(buffer-string)))
(defun dns-read (packet)
- (mm-with-unibyte-buffer
+ (with-temp-buffer
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(let ((spec nil)
- queries answers authorities additionals)
+ queries answers authorities additionals)
(insert packet)
(goto-char (point-min))
(push (list 'id (dns-read-bytes 2)) spec)
(let ((byte (dns-read-bytes 1)))
- (push (list 'response-p (if (zerop (logand byte (lsh 1 7))) nil t))
- spec)
- (let ((opcode (logand byte (lsh 7 3))))
- (push (list 'opcode
- (cond ((eq opcode 0) 'query)
- ((eq opcode 1) 'inverse-query)
- ((eq opcode 2) 'status)))
- spec))
- (push (list 'authoritative-p (if (zerop (logand byte (lsh 1 2)))
- nil t)) spec)
- (push (list 'truncated-p (if (zerop (logand byte (lsh 1 2))) nil t))
- spec)
- (push (list 'recursion-desired-p
- (if (zerop (logand byte (lsh 1 0))) nil t)) spec))
+ (push (list 'response-p (if (zerop (logand byte (lsh 1 7))) nil t))
+ spec)
+ (let ((opcode (logand byte (lsh 7 3))))
+ (push (list 'opcode
+ (cond ((eq opcode 0) 'query)
+ ((eq opcode 1) 'inverse-query)
+ ((eq opcode 2) 'status)))
+ spec))
+ (push (list 'authoritative-p (if (zerop (logand byte (lsh 1 2)))
+ nil t)) spec)
+ (push (list 'truncated-p (if (zerop (logand byte (lsh 1 2))) nil t))
+ spec)
+ (push (list 'recursion-desired-p
+ (if (zerop (logand byte (lsh 1 0))) nil t)) spec))
(let ((rc (logand (dns-read-bytes 1) 15)))
- (push (list 'response-code
- (cond
- ((eq rc 0) 'no-error)
- ((eq rc 1) 'format-error)
- ((eq rc 2) 'server-failure)
- ((eq rc 3) 'name-error)
- ((eq rc 4) 'not-implemented)
- ((eq rc 5) 'refused)))
- spec))
+ (push (list 'response-code
+ (cond
+ ((eq rc 0) 'no-error)
+ ((eq rc 1) 'format-error)
+ ((eq rc 2) 'server-failure)
+ ((eq rc 3) 'name-error)
+ ((eq rc 4) 'not-implemented)
+ ((eq rc 5) 'refused)))
+ spec))
(setq queries (dns-read-bytes 2))
(setq answers (dns-read-bytes 2))
(setq authorities (dns-read-bytes 2))
(setq additionals (dns-read-bytes 2))
(let ((qs nil))
- (dotimes (i queries)
- (push (list (dns-read-name)
- (list 'type (dns-inverse-get (dns-read-bytes 2)
- dns-query-types))
- (list 'class (dns-inverse-get (dns-read-bytes 2)
- dns-classes)))
- qs))
- (push (list 'queries qs) spec))
- (dolist (slot '(answers authorities additionals))
- (let ((qs nil)
- type)
- (dotimes (i (symbol-value slot))
- (push (list (dns-read-name)
- (list 'type
- (setq type (dns-inverse-get (dns-read-bytes 2)
- dns-query-types)))
- (list 'class (dns-inverse-get (dns-read-bytes 2)
- dns-classes))
- (list 'ttl (dns-read-bytes 4))
- (let ((length (dns-read-bytes 2)))
- (list 'data
- (dns-read-type
- (buffer-substring
- (point)
- (progn (forward-char length) (point)))
- type))))
- qs))
- (push (list slot qs) spec)))
- (nreverse spec))))
+ (dotimes (i queries)
+ (push (list (dns-read-name)
+ (list 'type (dns-inverse-get (dns-read-bytes 2)
+ dns-query-types))
+ (list 'class (dns-inverse-get (dns-read-bytes 2)
+ dns-classes)))
+ qs))
+ (push (list 'queries qs) spec))
+ (dolist (slot '(answers authorities additionals))
+ (let ((qs nil)
+ type)
+ (dotimes (i (symbol-value slot))
+ (push (list (dns-read-name)
+ (list 'type
+ (setq type (dns-inverse-get (dns-read-bytes 2)
+ dns-query-types)))
+ (list 'class (dns-inverse-get (dns-read-bytes 2)
+ dns-classes))
+ (list 'ttl (dns-read-bytes 4))
+ (let ((length (dns-read-bytes 2)))
+ (list 'data
+ (dns-read-type
+ (buffer-substring
+ (point)
+ (progn (forward-char length) (point)))
+ type))))
+ qs))
+ (push (list slot qs) spec)))
+ (nreverse spec))))
(defun dns-read-int32 ()
- ;; Full 32 bit Integers can't be handled by Emacs. If we use
- ;; floats, it works.
+ ;; Full 32 bit Integers can't be handled by 32-bit Emacsen. If we
+ ;; use floats, it works.
(format "%.0f" (+ (* (dns-read-bytes 1) 16777216.0)
(dns-read-bytes 3))))
(let ((buffer (current-buffer))
(point (point)))
(prog1
- (mm-with-unibyte-buffer
- (insert string)
- (goto-char (point-min))
- (cond
- ((eq type 'A)
- (let ((bytes nil))
- (dotimes (i 4)
- (push (dns-read-bytes 1) bytes))
- (mapconcat 'number-to-string (nreverse bytes) ".")))
- ((eq type 'AAAA)
- (let (hextets)
- (dotimes (i 8)
- (push (dns-read-bytes 2) hextets))
- (mapconcat (lambda (n) (format "%x" n)) (nreverse hextets) ":")))
- ((eq type 'SOA)
- (list (list 'mname (dns-read-name buffer))
- (list 'rname (dns-read-name buffer))
- (list 'serial (dns-read-int32))
- (list 'refresh (dns-read-int32))
- (list 'retry (dns-read-int32))
- (list 'expire (dns-read-int32))
- (list 'minimum (dns-read-int32))))
- ((eq type 'SRV)
- (list (list 'priority (dns-read-bytes 2))
- (list 'weight (dns-read-bytes 2))
- (list 'port (dns-read-bytes 2))
- (list 'target (dns-read-name buffer))))
- ((eq type 'MX)
- (cons (dns-read-bytes 2) (dns-read-name buffer)))
- ((or (eq type 'CNAME) (eq type 'NS) (eq type 'PTR))
- (dns-read-string-name string buffer))
- (t string)))
+ (with-temp-buffer
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
+ (insert string)
+ (goto-char (point-min))
+ (cond
+ ((eq type 'A)
+ (let ((bytes nil))
+ (dotimes (i 4)
+ (push (dns-read-bytes 1) bytes))
+ (mapconcat 'number-to-string (nreverse bytes) ".")))
+ ((eq type 'AAAA)
+ (let (hextets)
+ (dotimes (i 8)
+ (push (dns-read-bytes 2) hextets))
+ (mapconcat (lambda (n) (format "%x" n))
+ (nreverse hextets) ":")))
+ ((eq type 'SOA)
+ (list (list 'mname (dns-read-name buffer))
+ (list 'rname (dns-read-name buffer))
+ (list 'serial (dns-read-int32))
+ (list 'refresh (dns-read-int32))
+ (list 'retry (dns-read-int32))
+ (list 'expire (dns-read-int32))
+ (list 'minimum (dns-read-int32))))
+ ((eq type 'SRV)
+ (list (list 'priority (dns-read-bytes 2))
+ (list 'weight (dns-read-bytes 2))
+ (list 'port (dns-read-bytes 2))
+ (list 'target (dns-read-name buffer))))
+ ((eq type 'MX)
+ (cons (dns-read-bytes 2) (dns-read-name buffer)))
+ ((or (eq type 'CNAME) (eq type 'NS) (eq type 'PTR))
+ (dns-read-string-name string buffer))
+ (t string)))
(goto-char point))))
-(defun dns-parse-resolv-conf ()
- (when (file-exists-p "/etc/resolv.conf")
- (with-temp-buffer
- (insert-file-contents "/etc/resolv.conf")
- (goto-char (point-min))
- (while (re-search-forward "^nameserver[\t ]+\\([^ \t\n]+\\)" nil t)
- (push (match-string 1) dns-servers))
- (setq dns-servers (nreverse dns-servers)))))
+(declare-function network-interface-list "process.c")
+
+(defun dns-servers-up-to-date-p ()
+ "Return false if we need to recheck the list of DNS servers."
+ (and dns-servers
+ (or (eq dns-servers-valid-for-interfaces t)
+ ;; `network-interface-list' was introduced in Emacs 22.1.
+ (not (fboundp 'network-interface-list))
+ (equal dns-servers-valid-for-interfaces
+ (network-interface-list)))))
+
+(defun dns-set-servers ()
+ "Set `dns-servers' to a list of DNS servers or nil if none are found.
+Parses \"/etc/resolv.conf\" or calls \"nslookup\"."
+ (or (when (file-exists-p "/etc/resolv.conf")
+ (setq dns-servers nil)
+ (with-temp-buffer
+ (insert-file-contents "/etc/resolv.conf")
+ (goto-char (point-min))
+ (while (re-search-forward "^nameserver[\t ]+\\([^ \t\n]+\\)" nil t)
+ (push (match-string 1) dns-servers))
+ (setq dns-servers (nreverse dns-servers))))
+ (when (executable-find "nslookup")
+ (with-temp-buffer
+ (call-process "nslookup" nil t nil "localhost")
+ (goto-char (point-min))
+ (re-search-forward
+ "^Address:[ \t]*\\([0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+\\)" nil t)
+ (setq dns-servers (list (match-string 1))))))
+ (when (fboundp 'network-interface-list)
+ (setq dns-servers-valid-for-interfaces (network-interface-list))))
(defun dns-read-txt (string)
(if (> (length string) 1)
(defvar dns-cache (make-vector 4096 0))
-(defun query-dns-cached (name &optional type fullp reversep)
+(defun dns-query-cached (name &optional type fullp reversep)
(let* ((key (format "%s:%s:%s:%s" name type fullp reversep))
(sym (intern-soft key dns-cache)))
(if (and sym
(boundp sym))
(symbol-value sym)
- (let ((result (query-dns name type fullp reversep)))
+ (let ((result (dns-query name type fullp reversep)))
(set (intern key dns-cache) result)
result))))
-(defun query-dns (name &optional type fullp reversep)
+;; The old names `query-dns' and `query-dns-cached' weren't used in Emacs 23
+;; yet, so no alias are provided. --rsteib
+
+(defun dns-query (name &optional type fullp reversep)
"Query a DNS server for NAME of TYPE.
If FULLP, return the entire record returned.
If REVERSEP, look up an IP address."
(setq type (or type 'A))
- (unless dns-servers
- (dns-parse-resolv-conf))
+ (unless (dns-servers-up-to-date-p)
+ (dns-set-servers))
(when reversep
(setq name (concat
(if (not dns-servers)
(message "No DNS server configuration found")
- (mm-with-unibyte-buffer
+ (with-temp-buffer
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(let ((process (condition-case ()
- (dns-make-network-process (car dns-servers))
- (error
- (message "dns: Got an error while trying to talk to %s"
- (car dns-servers))
- nil)))
- (tcp-p (and (not (fboundp 'make-network-process))
- (not (featurep 'xemacs))))
- (step 100)
- (times (* dns-timeout 1000))
- (id (random 65000)))
- (when process
- (process-send-string
- process
- (dns-write `((id ,id)
- (opcode query)
- (queries ((,name (type ,type))))
- (recursion-desired-p t))
- tcp-p))
- (while (and (zerop (buffer-size))
- (> times 0))
- (sit-for (/ step 1000.0))
- (accept-process-output process 0 step)
- (decf times step))
- (ignore-errors
- (delete-process process))
- (when tcp-p
- (goto-char (point-min))
- (delete-region (point) (+ (point) 2)))
- (unless (zerop (buffer-size))
- (let ((result (dns-read (buffer-string))))
- (if fullp
- result
- (let ((answer (car (dns-get 'answers result))))
- (when (eq type (dns-get 'type answer))
- (if (eq type 'TXT)
- (dns-get-txt-answer (dns-get 'answers result))
- (dns-get 'data answer))))))))))))
+ (dns-make-network-process (car dns-servers))
+ (error
+ (message
+ "dns: Got an error while trying to talk to %s"
+ (car dns-servers))
+ nil)))
+ (tcp-p (and (not (fboundp 'make-network-process))
+ (not (featurep 'xemacs))))
+ (step 100)
+ (times (* dns-timeout 1000))
+ (id (random 65000)))
+ (when process
+ (process-send-string
+ process
+ (dns-write `((id ,id)
+ (opcode query)
+ (queries ((,name (type ,type))))
+ (recursion-desired-p t))
+ tcp-p))
+ (while (and (zerop (buffer-size))
+ (> times 0))
+ (sit-for (/ step 1000.0))
+ (accept-process-output process 0 step)
+ (setq times (- times step)))
+ (condition-case nil
+ (delete-process process)
+ (error nil))
+ (when (and tcp-p
+ (>= (buffer-size) 2))
+ (goto-char (point-min))
+ (delete-region (point) (+ (point) 2)))
+ (when (and (>= (buffer-size) 2)
+ ;; We had a time-out.
+ (> times 0))
+ (let ((result (dns-read (buffer-string))))
+ (if fullp
+ result
+ (let ((answer (car (dns-get 'answers result))))
+ (when (eq type (dns-get 'type answer))
+ (if (eq type 'TXT)
+ (dns-get-txt-answer (dns-get 'answers result))
+ (dns-get 'data answer))))))))))))
(provide 'dns)
-;;; arch-tag: d0edd0c4-4cce-4538-ae92-06c3356ee80a
;;; dns.el ends here
projects / gnus / blobdiff