zone, serv: Add support for SRV records.

[zone] / serv.lisp

diff --git a/serv.lisp b/serv.lisp
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+++ b/serv.lisp
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+;;; -*-lisp-*-
+;;;
+;;; Database of network service numbers
+;;;
+;;; (c) 2006 Straylight/Edgeware
+;;;
+
+;;;----- Licensing notice ---------------------------------------------------
+;;;
+;;; This program 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 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; This program 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 this program; if not, write to the Free Software Foundation,
+;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+(defpackage #:services
+  (:use #:common-lisp #:mdw.base #:mdw.str #:collect #:net #:anaphora)
+  (:export #:serv #:servp #:serv-name #:serv-aliases #:serv-port #:serv-proto
+          #:serv-by-name #:serv-by-port #:serv-add #:serv-list))
+
+(in-package #:services)
+
+(defstruct (serv (:predicate servp))
+  "Represents a service entry in /etc/services."
+  (name :nil :type keyword)
+  (aliases () :type list)
+  (port 0 :type (integer 0 65535))
+  (proto :tcp :type keyword))
+
+(let ((byname (make-hash-table))
+      (byport (make-hash-table)))
+
+  ;; Translation functions.
+  (defun serv-by-name (name &optional proto)
+    "Look up the service with the given NAME (or alias) and PROTO.  If PROTO
+     is nil, use a default protocol from a built-in list."
+    (let ((match (gethash name byname)))
+      (flet ((find-proto (proto)
+              (find proto match :key #'serv-proto)))
+       (cond ((null match) nil)
+             (proto (find-proto proto))
+             ((null (cdr match)) (car match))
+             (t (dolist (proto '(:tcp :udp :icmp) (car match))
+                  (awhen (find-proto proto)
+                    (return it))))))))
+
+  (defun serv-by-port (port &optional (proto :tcp))
+    "Look up the service with the given PORT number and PROTO."
+    (find proto (gethash port byport) :key #'serv-proto))
+
+  (defun serv-add (serv)
+    "Add a service to the global tables."
+    (push serv (gethash (serv-name serv) byname))
+    (push serv (gethash (serv-port serv) byport))
+    (dolist (alias (serv-aliases serv))
+      (push serv (gethash alias byname))))
+
+  ;; Read the whole damned lot.
+  (defun serv-list (&key (predicate (constantly t)))
+    "Return as a list the services which match PREDICATE (default all of
+     them)."
+    (let ((seen (make-hash-table :test #'eq)))
+      (collecting ()
+       (with-hash-table-iterator (next byport)
+         (loop
+           (multiple-value-bind (goodp port servs) (next)
+             (declare (ignore port))
+             (unless goodp
+               (return))
+             (unless (gethash servs seen)
+               (setf (gethash servs seen) t)
+               (dolist (serv servs)
+                 (when (funcall predicate serv)
+                   (collect serv))))))))))
+
+  ;; Insert ICMP entries.  This is a slight abuse of the `port' slot, but I
+  ;; think we'll live.  The names are taken straight from RFC792.
+  ;; (Actually the service class makes exactly the same abuse, so I think
+  ;; we're vindicated here.)
+  (dolist (item '((0 :echo-reply :ping-reply)
+                 (3 :destination-unreachable)
+                 (4 :source-quench)
+                 (5 :redirect)
+                 (8 :echo :echo-request :ping)
+                 (11 :time-exceeded)
+                 (12 :parameter-problem)
+                 (13 :timestamp :timestamp-request)
+                 (14 :timestamp-reply)
+                 (15 :information-request)
+                 (16 :information-reply)))
+    (destructuring-bind (type name . aliases) item
+      (serv-add (make-serv :name name
+                          :aliases aliases
+                          :port type
+                          :proto :icmp))))
+
+  ;; Read the /etc/services file.
+  (with-open-file (in "/etc/services")
+    (loop
+      (let ((line (read-line in nil)))
+       (unless line (return))
+       (block insert
+         (flet ((bail () (return-from insert))
+                (to-keyword (name) (intern (string-upcase name) :keyword)))
+           (let* ((end (or (position #\# line) (length line)))
+                  (words (or (str-split-words line :end end) (bail)))
+                  (name (to-keyword (or (car words) (bail))))
+                  (pp (or (cadr words) (bail)))
+                  (aliases (mapcar #'to-keyword (cddr words)))
+                  (slash (or (position #\/ pp) (bail)))
+                  (port (or (parse-integer pp
+                                           :start 0
+                                           :end slash
+                                           :junk-allowed t)
+                            (bail)))
+                  (proto (to-keyword (subseq pp (1+ slash)))))
+             (serv-add (make-serv :name name
+                                  :aliases aliases
+                                  :port port
+                                  :proto proto)))))))))
+
+;;;----- That's all, folks --------------------------------------------------