COMMON-NET: Added basic DNS communication.

[lisp-utils.git] / dns.lisp

diff --git a/dns.lisp b/dns.lisp
index f768d2c..cfb1750 100644 (file)
--- a/dns.lisp
+++ b/dns.lisp
@@ -380,3 +380,61 @@
   (let ((buf (make-dns-encode-state)))
     (encode-dns-packet buf packet)
     (slot-value buf 'packet-buf)))
+
+;;; DN format
+
+(defun parse-domain-name (name)
+  (declare (type string name))
+  (let ((l '())
+       (p 0))
+    (loop (let ((p2 (position #\. name :start p)))
+           (if p2
+               (if (= p2 (1- (length name)))
+                   (return (values l t))
+                   (setf l (append l (list (subseq name p p2)))
+                         p (1+ p2)))
+               (return (values (append l (list (subseq name p))) nil)))))))
+
+(defun unparse-domain-name (name)
+  (declare (type list name))
+  (let ((buf nil))
+    (dolist (label name buf)
+      (setf buf (if buf
+                   (concatenate 'string buf "." label)
+                   label)))))
+
+;;; Basic communication
+
+(defun dns-do-request (server packet)
+  (declare (type address server)
+          (type dns-packet packet))
+  (with-connection (sk server)
+    (socket-send sk (dns-encode packet))
+    (loop
+       (let ((resp (dns-decode (socket-recv sk))))
+        (when (= (dns-packet-txid resp)
+               (dns-packet-txid packet))
+          (return resp))))))
+
+(defun dns-std-request (queries &key (txid (random 65536)) (recurse t))
+  (let ((qlist (map 'list #'(lambda (o)
+                             (let ((name (first o))
+                                   (type (second o)))
+                               (make-instance 'resource-query
+                                              :name (etypecase name
+                                                      (string (parse-domain-name name))
+                                                      (list name))
+                                              :type type)))
+                   queries)))
+    (make-dns-packet :txid txid
+                    :recurse recurse
+                    :queries qlist)))
+
+;;; Misc.
+
+(defmethod print-object ((q resource-query) stream)
+  (with-slots (name type) q
+    (if *print-readably*
+       (format stream "~A: ~A" type (unparse-domain-name name))
+       (format stream "#<~S ~S ~S>" 'resource-query type (unparse-domain-name name)))))
+