sockets/dns/nameservers.lisp

   1 ;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Indent-tabs-mode: NIL -*-
   2 ;;;
   3 ;;; nameservers.lisp --- Nameservers management.
   4 ;;;
   5 ;;; Copyright (C) 2006-2007, Stelian Ionescu  <sionescu@common-lisp.net>
   6 ;;;
   7 ;;; This code is free software; you can redistribute it and/or
   8 ;;; modify it under the terms of the version 2.1 of
   9 ;;; the GNU Lesser General Public License as published by
  10 ;;; the Free Software Foundation, as clarified by the
  11 ;;; preamble found here:
  12 ;;;     http://opensource.franz.com/preamble.html
  13 ;;;
  14 ;;; This program is distributed in the hope that it will be useful,
  15 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;;; GNU General Public License for more details.
  18 ;;;
  19 ;;; You should have received a copy of the GNU Lesser General
  20 ;;; Public License along with this library; if not, write to the
  21 ;;; Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
  22 ;;; Boston, MA 02110-1301, USA
  23
  24 (in-package :net.sockets)
  25
  26 (defvar *resolv.conf-file* "/etc/resolv.conf")
  27
  28 (defvar *dns-nameservers* nil
  29   "List of the DNS nameservers to use.")
  30
  31 (defvar *dns-domain* nil
  32   "The current machine's domain.")
  33
  34 (defvar *dns-search-domain* nil
  35   "A domain name to be appended to the name to be searched when
  36 the latter does not contain dots.")
  37
  38 (defvar *resolvconf-lock* (bt:make-lock "/etc/resolv.conf lock"))
  39
  40 ;;; Only parses NAMESERVER, DOMAIN and SEARCH directives, for now.
  41 (defun parse-/etc/resolv.conf (file)
  42   (let (nameservers domain search-domain)
  43     (flet ((parse-one-line (tokens)
  44              (when (< (length tokens) 2) (error 'parse-error))
  45              (destructuring-bind (option value &rest more-values) tokens
  46                (switch (option :test #'string-equal)
  47                  ("nameserver" (ignore-parse-errors
  48                                  (push (ensure-address value)
  49                                        nameservers)))
  50                  ("domain" (setf domain value))
  51                  ("search" (setf search-domain (cons value more-values)))))))
  52       (iterate ((tokens (serialize-etc-file file)))
  53         (ignore-errors (parse-one-line tokens)))
  54       (values (nreverse nameservers) domain search-domain))))
  55
  56 (defun update-dns-parameters (file)
  57   (multiple-value-bind (ns domain search)
  58       (parse-/etc/resolv.conf file)
  59     (setf *dns-nameservers* (or ns +ipv4-loopback+)
  60           ;; everything after the first dot
  61           *dns-domain* (cdr (split-sequence #\. domain :count 2))
  62           *dns-search-domain* search)))
  63
  64 (defvar *resolv.conf-monitor*
  65   (make-instance 'file-monitor
  66                  :file *resolv.conf-file*
  67                  :update-fn 'update-dns-parameters
  68                  :lock *resolvconf-lock*))