X-Git-Url: http://cgit.sxemacs.org/?p=packages;a=blobdiff_plain;f=xemacs-packages%2Fgnus%2Flisp%2Fdns.el;fp=xemacs-packages%2Fgnus%2Flisp%2Fdns.el;h=487cfc9d080a52c1bdb3291ab395f9a402d95c9d;hp=0000000000000000000000000000000000000000;hb=ddbcce55bee95abbe2d79a9aa26ee08a47b284db;hpb=e10974b04b06bb129bf57b2c9edfc950caabc073 diff --git a/xemacs-packages/gnus/lisp/dns.el b/xemacs-packages/gnus/lisp/dns.el new file mode 100644 index 00000000..487cfc9d --- /dev/null +++ b/xemacs-packages/gnus/lisp/dns.el @@ -0,0 +1,459 @@ +;;; dns.el --- Domain Name Service lookups + +;; Copyright (C) 2002-2016 Free Software Foundation, Inc. + +;; Author: Lars Magne Ingebrigtsen +;; Keywords: network comm + +;; This file is part of GNU Emacs. + +;; 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 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 +;; GNU General Public License for more details. + +;; You should have received a copy of the GNU General Public License +;; along with GNU Emacs. If not, see . + +;;; Commentary: + +;;; Code: + +(defvar dns-timeout 5 + "How many seconds to wait when doing DNS queries.") + +(defvar dns-servers nil + "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 + '((A 1) + (NS 2) + (MD 3) + (MF 4) + (CNAME 5) + (SOA 6) + (MB 7) + (MG 8) + (MR 9) + (NULL 10) + (WKS 11) + (PTR 12) + (HINFO 13) + (MINFO 14) + (MX 15) + (TXT 16) + (AAAA 28) ; RFC3596 + (SRV 33) ; RFC2782 + (AXFR 252) + (MAILB 253) + (MAILA 254) + (* 255)) + "Names of query types and their values.") + +(defvar dns-classes + '((IN 1) + (CS 2) + (CH 3) + (HS 4)) + "Classes of queries.") + +(defun dns-write-bytes (value &optional length) + (let (bytes) + (dotimes (i (or length 1)) + (push (% value 256) bytes) + (setq value (/ value 256))) + (dolist (byte bytes) + (insert byte)))) + +(defun dns-read-bytes (length) + (let ((value 0)) + (dotimes (i length) + (setq value (logior (* value 256) (following-char))) + (forward-char 1)) + value)) + +(defun dns-get (type spec) + (cadr (assq type spec))) + +(defun dns-inverse-get (value spec) + (let ((found nil)) + (while (and (not found) + spec) + (if (eq value (cadr (car spec))) + (setq found (caar spec)) + (pop spec))) + found)) + +(defun dns-write-name (name) + (dolist (part (split-string name "\\.")) + (dns-write-bytes (length part)) + (insert part)) + (dns-write-bytes 0)) + +(defun dns-read-string-name (string buffer) + (with-temp-buffer + (unless (featurep 'xemacs) (set-buffer-multibyte nil)) + (insert string) + (goto-char (point-min)) + (dns-read-name buffer))) + +(defun dns-read-name (&optional buffer) + (let ((ended nil) + (name nil) + length) + (while (not ended) + (setq length (dns-read-bytes 1)) + (if (= 192 (logand length (lsh 3 6))) + (let ((offset (+ (* (logand 63 length) 256) + (dns-read-bytes 1)))) + (save-excursion + (when buffer + (set-buffer buffer)) + (goto-char (1+ offset)) + (setq ended (dns-read-name buffer)))) + (if (zerop length) + (setq ended t) + (push (buffer-substring (point) + (progn (forward-char length) (point))) + name)))) + (if (stringp ended) + (if (null name) + ended + (concat (mapconcat 'identity (nreverse name) ".") "." ended)) + (mapconcat 'identity (nreverse name) ".")))) + +(defun dns-write (spec &optional tcp-p) + "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 'response-p spec) 1 0) -7) + (lsh + (cond + ((eq (dns-get 'opcode spec) 'query) 0) + ((eq (dns-get 'opcode spec) 'inverse-query) 1) + ((eq (dns-get 'opcode spec) 'status) 2) + (t (error "No such opcode: %s" (dns-get 'opcode spec)))) + -3) + (lsh (if (dns-get 'authoritative-p spec) 1 0) -2) + (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 + ((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) + ((eq (dns-get 'response-code spec) 'name-error) 3) + ((eq (dns-get 'response-code spec) 'not-implemented) 4) + ((eq (dns-get 'response-code spec) 'refused) 5) + (t 0))) + (dns-write-bytes (length (dns-get 'queries spec)) 2) + (dns-write-bytes (length (dns-get 'answers spec)) 2) + (dns-write-bytes (length (dns-get 'authorities spec)) 2) + (dns-write-bytes (length (dns-get 'additionals spec)) 2) + (dolist (query (dns-get 'queries spec)) + (dns-write-name (car query)) + (dns-write-bytes (cadr (assq (or (dns-get 'type query) 'A) + dns-query-types)) 2) + (dns-write-bytes (cadr (assq (or (dns-get 'class query) 'IN) + dns-classes)) 2)) + (dolist (slot '(answers authorities additionals)) + (dolist (resource (dns-get slot spec)) + (dns-write-name (car resource)) + (dns-write-bytes (cadr (assq (dns-get 'type resource) dns-query-types)) + 2) + (dns-write-bytes (cadr (assq (dns-get 'class resource) dns-classes)) + 2) + (dns-write-bytes (dns-get 'ttl resource) 4) + (dns-write-bytes (length (dns-get 'data resource)) 2) + (insert (dns-get 'data resource)))) + (when tcp-p + (goto-char (point-min)) + (dns-write-bytes (buffer-size) 2)) + (buffer-string))) + +(defun dns-read (packet) + (with-temp-buffer + (unless (featurep 'xemacs) (set-buffer-multibyte nil)) + (let ((spec nil) + 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)) + (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)) + (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)))) + +(defun dns-read-int32 () + ;; 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)))) + +(defun dns-read-type (string type) + (let ((buffer (current-buffer)) + (point (point))) + (prog1 + (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)))) + +(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) + (substring string 1) + string)) + +(defun dns-get-txt-answer (answers) + (let ((result "") + (do-next nil)) + (dolist (answer answers) + (dolist (elem answer) + (when (consp elem) + (cond + ((eq (car elem) 'type) + (setq do-next (eq (cadr elem) 'TXT))) + ((eq (car elem) 'data) + (when do-next + (setq result (concat result (dns-read-txt (cadr elem)))))))))) + result)) + +;;; Interface functions. +(defmacro dns-make-network-process (server) + (if (featurep 'xemacs) + `(let ((coding-system-for-read 'binary) + (coding-system-for-write 'binary)) + (open-network-stream "dns" (current-buffer) + ,server "domain" 'udp)) + `(let ((server ,server) + (coding-system-for-read 'binary) + (coding-system-for-write 'binary)) + (if (fboundp 'make-network-process) + (make-network-process + :name "dns" + :coding 'binary + :buffer (current-buffer) + :host server + :service "domain" + :type 'datagram) + ;; Older versions of Emacs doesn't have + ;; `make-network-process', so we fall back on opening a TCP + ;; connection to the DNS server. + (open-network-stream "dns" (current-buffer) server "domain"))))) + +(defvar dns-cache (make-vector 4096 0)) + +(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 (dns-query name type fullp reversep))) + (set (intern key dns-cache) result) + result)))) + +;; 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-up-to-date-p) + (dns-set-servers)) + + (when reversep + (setq name (concat + (mapconcat 'identity (nreverse (split-string name "\\.")) ".") + ".in-addr.arpa") + type 'PTR)) + + (if (not dns-servers) + (message "No DNS server configuration found") + (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) + (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) + +;;; dns.el ends here