;;; dns.el --- Domain Name Service lookups
-;; Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
-;; Free Software Foundation, Inc.
+;; Copyright (C) 2002-2015 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: network comm
"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:
(defvar dns-query-types
(defun dns-read-string-name (string buffer)
(with-temp-buffer
- (set-buffer-multibyte nil)
+ (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
- (set-buffer-multibyte nil)
+ (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)
(defun dns-read (packet)
(with-temp-buffer
- (set-buffer-multibyte nil)
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(let ((spec nil)
queries answers authorities additionals)
(insert packet)
(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))))
(point (point)))
(prog1
(with-temp-buffer
- (set-buffer-multibyte nil)
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(insert string)
(goto-char (point-min))
(cond
(t string)))
(goto-char point))))
+(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\"."
(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)))))))
+ (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)
If FULLP, return the entire record returned.
If REVERSEP, look up an IP address."
(setq type (or type 'A))
- (unless dns-servers
+ (unless (dns-servers-up-to-date-p)
(dns-set-servers))
(when reversep
(if (not dns-servers)
(message "No DNS server configuration found")
(with-temp-buffer
- (set-buffer-multibyte nil)
+ (unless (featurep 'xemacs) (set-buffer-multibyte nil))
(let ((process (condition-case ()
(dns-make-network-process (car dns-servers))
(error
(provide 'dns)
-;; arch-tag: d0edd0c4-4cce-4538-ae92-06c3356ee80a
;;; dns.el ends here