diff --git a/dns.scm b/dns.scm
index 1cc90c1..aad89c7 100644
--- a/dns.scm
+++ b/dns.scm
@@ -6,13 +6,9 @@
 ; based on the PLT-implementation.
 ; 
 ;
-; TODO: -*!!! CHECK-ANSWER !!! 
-;        *(wrong: if check-answer is not successfull, bad hostname is returned)
-;        *solution: error conditions -> if thrown, return #f
+; TODO: 
 ;       - test, test, test
 ;       - types from newer RFCs (41, unknown)
-;       -*error conditions
-;       -*better interface (found or #f)
 ;       - more documentation
 ;
 ;
@@ -42,6 +38,90 @@
 (define *debug* #f)
 
 
+;; --- error conditions
+(define-condition-type 'invalid-type '())
+(define invalid-type? (condition-predicate 'invalid-type))
+
+(define-condition-type 'invalid-class '())
+(define invalid-class? (condition-predicate 'invalid-class))
+
+(define-condition-type 'parse-error '())
+(define parse-error? (condition-predicate 'parse))
+
+(define-condition-type 'unexpected-eof-from-server '())
+(define unexpected-eof-from-server? (condition-predicate 'unexpected-eof-from-server))
+
+(define-condition-type 'bad-address '())
+(define bad-address? (condition-predicate 'bad-address))
+
+(define-condition-type 'no-nameservers '())
+(define no-nameservers? (condition-predicate 'no-nameservers))
+
+(define-condition-type 'not-a-hostname '())
+(define not-a-hostname? (condition-predicate 'not-a-hostname))
+
+(define-condition-type 'not-a-ip '())
+(define not-a-ip? (condition-predicate 'not-a-ip))
+
+
+(define-condition-type 'dns-format-error '())
+(define dns-format-error? (condition-predicate 'dns-format-error))
+
+(define-condition-type 'dns-server-failure '())
+(define dns-server-failure? (condition-predicate 'dns-server-failure))
+
+(define-condition-type 'dns-name-error '())
+(define dns-name-error? (condition-predicate 'dns-name-error))
+
+(define-condition-type 'dns-not-implemented '())
+(define dns-not-implemented? (condition-predicate 'dns-not-implemented))
+
+(define-condition-type 'dns-refused '())
+(define dns-refused? (condition-predicate 'dns-refused))
+
+
+(define-condition-type 'dns-error '(dns-format-error
+				    dns-server-failure
+				    dns-name-error
+				    dns-not-implemented
+				    dns-refused))
+
+(define dns-error? (condition-predicate 'dns-error))
+
+
+;; called by the error-handlers, prints out error descriptions
+(define (dns-error-messages condition more)
+  (cond
+   ((invalid-type? condition)
+    (display "make-octet-question: invalid DNS query type\n"))
+   ((invalid-class? condition)
+    (display "make-octet-question: invalid DNS query class\n"))
+   ((parse-error? condition)
+    (display "parse: error parsing server message\n"))
+   ((unexpected-eof-from-server? condition)
+    (display "send-receive-message: unexpected EOF from server\n"))
+   ((bad-address? condition)
+    (display "dns-get-information: bad address (in combination with query type)\n"))
+   ((no-nameservers? condition)
+    (display "dns-find-nameserver: no nameservers found in /etc/resolv.conf\n"))
+   ((not-a-hostname? condition)
+    (display "no hostname given\n"))
+   ((not-a-ip? condition)
+    (display "no ip given\n"))
+   ((dns-format-error? condition) 
+    (display "error from server: (1) format error\n"))
+   ((dns-server-failure? condition) 
+    (display "error from server: (2) server failure\n"))
+   ((dns-name-error? condition) 
+    (display "error from server: (3) name error\n"))
+   ((dns-not-implemented? condition) 
+    (display "error from server: (4) not implemented\n"))
+   ((dns-refused? condition) 
+    (display "error from server: (5) refused\n"))
+   (else (more))))
+  
+
+
 ;;; -- globals and types
 
 ;; off
@@ -84,7 +164,7 @@
 (define (cossa i l)
   (if *debug* (display "cossa\n"))
   (cond
-   ((null? l) 'unknown) ;;(error "dns-message: type not implemented: " i))
+   ((null? l) 'unknown)
    ((equal? (cadar l) i)
     (car l))
    (else (cossa i (cdr l)))))
@@ -164,7 +244,7 @@
       => (lambda (match)
 	   (loop (match:substring match 2) (append result (list (ascii->char (string->number (match:substring match 1))))))))
      (else
-       (append result (list (ascii->char (string->number s))))))))
+      (append result (list (ascii->char (string->number s))))))))
 
 ;; calculates a "random" number, needed for message-ids
 (define random
@@ -292,9 +372,9 @@
 (define (make-octet-question name type class)
   (if *debug* (display "make-octet-question\n"))
   (if (not (assoc type types))
-      (error "make-octet-question: invalid DNS query type ~A" type))
+      (signal 'invalid-type))
   (if (not (assoc class classes))
-      (error "make-octet-question: invalid DNS query class ~A" class))
+      (signal 'invalid-class))
 
   (let* ((qname   (name->octets name))
 	 (qtype   (number->octet-pair (cadr (assoc type types))))
@@ -308,7 +388,7 @@
   (append
    (make-std-octet-query-header id 1)
    (make-octet-question name type class)))
-  
+
 
 ;; makes a resource record for ans, nss, ars (name, type, class, ttl, data)
 (define (make-octet-rr name type class ttl rdata)
@@ -516,15 +596,15 @@
 
    ((eq? type 'mx)
     (make-rr-data-mx (octet-pair->number (car data) (cadr data))
-		(call-with-values
-		 (lambda ()(parse-name (cddr data) message))
-		 (lambda (name rest) name))))
+		     (call-with-values
+		      (lambda ()(parse-name (cddr data) message))
+		      (lambda (name rest) name))))
 
    ((eq? type 'ptr)
     (make-rr-data-ptr (call-with-values
-		  (lambda () (parse-name data message))
-		  (lambda (name rest) name))))
-  
+		       (lambda () (parse-name data message))
+		       (lambda (name rest) name))))
+   
    ((eq? type 'soa)
     (call-with-values
      (lambda () (parse-name data message))
@@ -571,16 +651,16 @@
   (if *debug* (display "parse-flags\n"))
   (let ((v0 (list-ref message 2))
 	(v1 (list-ref message 3)))
-      ;; Check for error code:
-      (let ((rcode  (bitwise-and #xf (char->ascii v1)))
-	    (z      (arithmetic-shift (bitwise-and 112 (char->ascii v1)) -4))
-	    (ra     (arithmetic-shift (bitwise-and 64 (char->ascii v1)) -7))
-	    (rd     (bitwise-and 1 (char->ascii v0)))
-	    (tc     (arithmetic-shift (bitwise-and 2 (char->ascii v0)) -1))
-	    (aa     (arithmetic-shift (bitwise-and 4 (char->ascii v0)) -2))
-	    (opcode (arithmetic-shift (bitwise-and 120 (char->ascii v0)) -3))
-	    (qr     (arithmetic-shift (bitwise-and 128 (char->ascii v0)) -7))) 
-	(make-flags qr opcode aa tc rd ra z rcode))))
+    ;; Check for error code:
+    (let ((rcode  (bitwise-and #xf (char->ascii v1)))
+	  (z      (arithmetic-shift (bitwise-and 112 (char->ascii v1)) -4))
+	  (ra     (arithmetic-shift (bitwise-and 64 (char->ascii v1)) -7))
+	  (rd     (bitwise-and 1 (char->ascii v0)))
+	  (tc     (arithmetic-shift (bitwise-and 2 (char->ascii v0)) -1))
+	  (aa     (arithmetic-shift (bitwise-and 4 (char->ascii v0)) -2))
+	  (opcode (arithmetic-shift (bitwise-and 120 (char->ascii v0)) -3))
+	  (qr     (arithmetic-shift (bitwise-and 128 (char->ascii v0)) -7))) 
+      (make-flags qr opcode aa tc rd ra z rcode))))
 
 
 ;; parses a message-header. returns the header.
@@ -593,7 +673,7 @@
 	(ns-count (octet-pair->number (list-ref message 8) (list-ref message 9)))
 	(ar-count (octet-pair->number (list-ref message 10) (list-ref message 11))))
     (make-header id flags qd-count an-count ns-count ar-count)))
-  
+
 
 ;; parses a message. returns the parsed message.
 (define (parse message)
@@ -613,7 +693,7 @@
 	      (lambda () (parse-n parse-rr start message (header:arc header)))
 	      (lambda (ars start)
 		(if (not (null? start))
-		    (error "parse: error parsing server message"))
+		    (signal 'parse-error))
 		(make-message header qds ans nss ars message)))))))))))
 
 
@@ -629,14 +709,13 @@
       (display "send-receive-message: bad reply id from server"))
   ;; Check for error code:
   (let ((rcode (flags:rcode (parse-flags reply))))
-    (if (not (zero? 0));rcode))
-	(error "send-receive-message: error from server: ~A"
-	       (case rcode
-		 ((1) "format error")
-		 ((2) "server failure")
-		 ((3) "name error")
-		 ((4) "not implemented")
-		 ((5) "refused"))))))
+    (if (not (zero? rcode))
+	(case rcode
+	  ((1) (signal 'dns-format-error))
+	  ((2) (signal 'dns-server-failure))
+	  ((3) (signal 'dns-name-error))
+	  ((4) (signal 'dns-not-implemented))
+	  ((5) (signal 'dns-refused))))))
 
 ;; #t if message is truncated (could happen via UDP)
 (define (truncated? reply)
@@ -661,13 +740,13 @@
 	       (lambda ()
 		 (display (list->string (add-size-tag query)) w)
 		 (force-output w)
-	       
+		 
 		 (let ((a (read-char r))
 		       (b (read-char r)))
 		   (let ((len (octet-pair->number a b)))
 		     (let ((s (read-string len r)))
 		       (if (not (= len (string-length s)))
-			   (error "send-receive-message: unexpected EOF from server"))
+			   (signal 'unexpected-eof-from-server))
 		       (string->list s)))))
 	       (lambda ()
 		 (close-socket socket)))))))
@@ -785,8 +864,7 @@
 	   (try-recursive
 	    (lambda (auth? nss)
 	      (if (or auth? (null? nss)) 
-		  (error "dns-get-information: bad address (in combination with query-type)" 
-			 (question:name (car (message:questions (parse question)))))
+		  (signal 'bad-address)
 		  (let* ((ns (and (eq? (rr:type (car nss)) 'a) (rr-data-a:ip (rr:data (car nss)))))
 			 (dns-msg (if (and ns
 					   (not (member ns tried))
@@ -820,7 +898,7 @@
 	  (cond
 	   ((eof-object? l)
 	    (if (null? ns)
-		(error "dns-find-nameserver-list: no nameserver(s) found in /etc/resolv.conf")
+		(signal 'no-nameservers)
 		ns))
 	   ((regexp-search (posix-string->regexp "nameserver[ 	]+([0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+)") l)
 	    => (lambda (match)
@@ -833,7 +911,7 @@
 (define (dns-find-nameserver)
   (let ((ns (dns-find-nameserver-list)))
     (if (null? ns)
-	(error "dns-find-nameserver: no nameserver found in /etc/resolv.conf")
+	(signal 'no-nameservers)
 	(car ns))))
 
 
@@ -857,7 +935,7 @@
 			      (enqueue! queue result)
 			      (display "received reply from ")(display nameserver)(display ": ")(display result)(newline)
 			      (release-lock lock)))))
-	     (dns-find-nameserver-list))))
+		       (dns-find-nameserver-list))))
 
     (let loop ((count (length nameserver-list)))
       (obtain-lock lock)
@@ -865,7 +943,7 @@
 	(if (or result (= 1 (length nameserver-list)))
 	    result
 	    (loop (- count 1)))))))
-		       
+
 ;; checks the arguments of the dns-lookup-* functions.
 ;; if a nameserver-name is given and not a nameserver-ip
 ;; (dns-lookup-name nameserver) is called.
@@ -881,59 +959,80 @@
 ;; dns-lookup with more options than dns-lookup-*
 ;; optional: nameserver could be passed to the function.
 (define (dns-lookup name type . args)
-  (let* ((ip-string (ip-string->in-addr name))
-	 (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
-		       (make-octet-query-message (random 256) ip-string type 'in)
-		       (make-octet-query-message (random 256) name type 'in)))
-	 (use-cache? #t)
-	 (protocol 'udp)
-	 (nameserver (check-args args))
-	 (check-answer (lambda (dns-msg) #t))
-	 (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
-	 (answers (message:answers (dns-message:reply dns-msg))))
-    (if (not (null? answers))
-	(for-each (lambda (x) (show-dns-message x)(newline)) answers)
-	(display "no answers received - but resolved information in other sections.\n"))
-    dns-msg))
+  (call-with-current-continuation
+   (lambda (exit)
+     (with-handler
+      (lambda (condition more)
+	(dns-error-messages condition more)
+	(exit #f))
+      (lambda ()
+	(let* ((ip-string (ip-string->in-addr name))
+	       (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
+			     (make-octet-query-message (random 256) ip-string type 'in)
+			     (make-octet-query-message (random 256) name type 'in)))
+	       (use-cache? #t)
+	       (protocol 'udp)
+	       (nameserver (check-args args))
+	       (check-answer (lambda (dns-msg) #t))
+	       (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
+	       (answers (message:answers (dns-message:reply dns-msg))))
+	  (if (not (null? answers))
+	      (for-each (lambda (x) (show-dns-message x)(newline)) answers)
+	      (display "no answers received - but resolved information in other sections.\n"))
+	  dns-msg))))))
 
 
 
 ;; looks up a hostname, returns an ip.
 ;; (dns-lookup-name <name> [nameserver])
 (define (dns-lookup-name name . args)
-  (let* ((ip-string (ip-string->in-addr name))
-	 (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
-		       (error "dns-lookup-name: no valid hostname, suppose it is an ip")
-		       (make-octet-query-message (random 256) name 'a 'in)))
-	 (use-cache? #t)
-	 (protocol 'udp)
-	 (nameserver (check-args args))
-	 (check-answer (lambda (dns-msg) 
-			(let* ((reply (dns-message:reply dns-msg))
-			       (answers (message:answers reply)))
-			(not (null? (filter-type answers 'a))))))
-	 (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
-	 (answers (filter-type (message:answers (dns-message:reply dns-msg)) 'a)))
-    (rr-data-a:ip (rr:data (car answers)))))
+  (call-with-current-continuation
+   (lambda (exit)
+     (with-handler
+      (lambda (condition more)
+	(dns-error-messages condition more)
+	(exit #f))
+      (lambda ()
+	(let* ((ip-string (ip-string->in-addr name))
+	       (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
+			     (signal 'not-a-hostname)
+			     (make-octet-query-message (random 256) name 'a 'in)))
+	       (use-cache? #t)
+	       (protocol 'udp)
+	       (nameserver (check-args args))
+	       (check-answer (lambda (dns-msg) 
+			       (let* ((reply (dns-message:reply dns-msg))
+				      (answers (message:answers reply)))
+				 (not (null? (filter-type answers 'a))))))
+	       (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
+	       (answers (filter-type (message:answers (dns-message:reply dns-msg)) 'a)))
+	  (rr-data-a:ip (rr:data (car answers)))))))))
 
 
 ;; looks up an ip, returns a hostname
 ;; (dns-inverse-lookup <name> [nameserver])
 (define (dns-inverse-lookup ip . args)
-  (let* ((ip-string (ip-string->in-addr ip))
-	 (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
-		       (make-octet-query-message (random 256) ip-string 'ptr 'in)
-		       (error "dns-inverse-lookup: no valid ip")))
-	 (use-cache? #t)
-	 (protocol 'udp)
-	 (nameserver (check-args args))
-	 (check-answer (lambda (dns-msg) 
-			 (let* ((reply (dns-message:reply dns-msg))
-				(answers (message:answers reply)))
-			   (not (null? (filter-type answers 'ptr))))))
-	 (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
-	 (answers (filter-type (message:answers (dns-message:reply dns-msg)) 'ptr)))
-    (rr-data-ptr:name (rr:data (car answers)))))
+  (call-with-current-continuation
+   (lambda (exit)
+     (with-handler
+      (lambda (condition more)
+	(dns-error-messages condition more)
+	(exit #f))
+      (lambda ()
+	(let* ((ip-string (ip-string->in-addr ip))
+	       (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
+			     (make-octet-query-message (random 256) ip-string 'ptr 'in)
+			     (signal 'not-a-ip)))
+	       (use-cache? #t)
+	       (protocol 'udp)
+	       (nameserver (check-args args))
+	       (check-answer (lambda (dns-msg) 
+			       (let* ((reply (dns-message:reply dns-msg))
+				      (answers (message:answers reply)))
+				 (not (null? (filter-type answers 'ptr))))))
+	       (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
+	       (answers (filter-type (message:answers (dns-message:reply dns-msg)) 'ptr)))
+	  (rr-data-ptr:name (rr:data (car answers)))))))))
 
 (define dns-lookup-ip dns-inverse-lookup)
 
@@ -942,27 +1041,34 @@
 ;; returns a list of nameservers
 ;; (dns-lookup-nameserver <name> [nameserver])
 (define (dns-lookup-nameserver name . args)
-  (let* ((ip-string (ip-string->in-addr name))
-	 (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
-		       (error "dns-lookup-name: no valid hostname, suppose it is an ip")
-		       (make-octet-query-message (random 256) name 'ns 'in)))
-	 (use-cache? #t)
-	 (protocol 'udp)
-	 (nameserver (check-args args))
-	 (check-answer (lambda (dns-msg) 
-			(let* ((reply (dns-message:reply dns-msg))
-			       (answers (message:answers reply))
-			       (nameservers (message:nameservers reply)))
-			  (or (not (null? (filter-type nameservers 'soa)))
-			      (not (null? (filter-type answers 'ns)))))))
-	 (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
-	 (reply (dns-message:reply dns-msg))
-	 (soa (filter-type (message:nameservers reply) 'soa))
-	 (nss (filter-type (message:answers reply) 'ns))
-	 (add (filter-type (message:additionals reply) 'a)))
-    (if (null? nss)
-	(list (dns-lookup-name (rr-data-soa:mname (rr:data (car soa)))))
-	(map (lambda (elem) (rr-data-a:ip (rr:data elem))) add))))
+  (call-with-current-continuation
+   (lambda (exit)
+     (with-handler
+      (lambda (condition more)
+	(dns-error-messages condition more)
+	(exit #f))
+      (lambda ()
+	(let* ((ip-string (ip-string->in-addr name))
+	       (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
+			     (signal 'not-a-hostname)
+			     (make-octet-query-message (random 256) name 'ns 'in)))
+	       (use-cache? #t)
+	       (protocol 'udp)
+	       (nameserver (check-args args))
+	       (check-answer (lambda (dns-msg) 
+			       (let* ((reply (dns-message:reply dns-msg))
+				      (answers (message:answers reply))
+				      (nameservers (message:nameservers reply)))
+				 (or (not (null? (filter-type nameservers 'soa)))
+				     (not (null? (filter-type answers 'ns)))))))
+	       (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
+	       (reply (dns-message:reply dns-msg))
+	       (soa (filter-type (message:nameservers reply) 'soa))
+	       (nss (filter-type (message:answers reply) 'ns))
+	       (add (filter-type (message:additionals reply) 'a)))
+	  (if (null? nss)
+	      (list (dns-lookup-name (rr-data-soa:mname (rr:data (car soa)))))
+	      (map (lambda (elem) (rr-data-a:ip (rr:data elem))) add))))))))
 
 
 ;; looks up a mail-exchanger for a hostname.
@@ -971,36 +1077,43 @@
 ;; implementation based on RFC2821
 ;; (dns-lookup-mail-exchanger <name> [nameserver])
 (define (dns-lookup-mail-exchanger name . args)
-  (let* ((ip-string (ip-string->in-addr name))
-	 (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
-		       (error "dns-lookup-name: no valid hostname, suppose it is an ip")
-		       (make-octet-query-message (random 256) name 'mx 'in)))
-	 (use-cache? #t)
-	 (protocol 'tcp)
-	 (nameserver (check-args args))
-	 (check-answer (lambda (dns-msg) 
-			(let* ((reply (dns-message:reply dns-msg))
-			       (answers (message:answers reply))
-			       (nameservers (message:nameservers reply)))
-			  (or (not (null? (filter-type answers 'mx)))
-			      (not (null? (filter-type answers 'cname)))
-			      (not (null? (filter-type answers 'a)))))))
-	 (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
-	 (reply (dns-message:reply dns-msg))
-	 (mx (filter-type (message:answers reply) 'mx))
-	 (soa (filter-type (message:nameservers reply) 'soa))
-	 (cname (filter-type (message:answers reply) 'cname))
-	 (a (filter-type (message:answers reply) 'a)))
+  (call-with-current-continuation
+   (lambda (exit)
+     (with-handler
+      (lambda (condition more)
+	(dns-error-messages condition more)
+	(exit #f))
+      (lambda ()
+	(let* ((ip-string (ip-string->in-addr name))
+	       (question (if ip-string ; if name is a ip-addr, the query is a in-addr.arpa address
+			     (signal 'not-a-hostname)
+			     (make-octet-query-message (random 256) name 'mx 'in)))
+	       (use-cache? #t)
+	       (protocol 'tcp)
+	       (nameserver (check-args args))
+	       (check-answer (lambda (dns-msg) 
+			       (let* ((reply (dns-message:reply dns-msg))
+				      (answers (message:answers reply))
+				      (nameservers (message:nameservers reply)))
+				 (or (not (null? (filter-type answers 'mx)))
+				     (not (null? (filter-type answers 'cname)))
+				     (not (null? (filter-type answers 'a)))))))
+	       (dns-msg (dns-get-information question use-cache? protocol nameserver check-answer))
+	       (reply (dns-message:reply dns-msg))
+	       (mx (filter-type (message:answers reply) 'mx))
+	       (soa (filter-type (message:nameservers reply) 'soa))
+	       (cname (filter-type (message:answers reply) 'cname))
+	       (a (filter-type (message:answers reply) 'a)))
 
-    (cond
-     ((not (null? a)) 
-      (list (rr-data-a:ip (rr:data (car a)))))
-     ((not (null? cname))
-      (dns-lookup-mail-exchanger (rr-data-cname:name (rr:data (car cname)))))
-     ((null? mx) 
-      (list (rr-data-soa:rname (rr:data (car soa)))))
-     (else
-      (map (lambda (elem) (rr-data-mx:exchanger (rr:data elem))) (sort-by-preference mx))))))
+	  (cond
+	   ((not (null? a)) 
+	    (list (rr-data-a:ip (rr:data (car a)))))
+	   ((not (null? cname))
+	    (dns-lookup-mail-exchanger (rr-data-cname:name (rr:data (car cname)))))
+	   ((null? mx) 
+	    (list (rr-data-soa:rname (rr:data (car soa)))))
+	   (else
+	    (map (lambda (elem) (rr-data-mx:exchanger (rr:data elem))) (sort-by-preference mx))))))))))
 
 
 
@@ -1010,99 +1123,99 @@
   (let* ((d 
 	  (lambda (n s1 s2)
 	    (letrec ((loop (lambda (n)
-			  (if (zero? n)
-			      ""
-			      (string-append " " (loop (- n 1)))))))
+			     (if (zero? n)
+				 ""
+				 (string-append " " (loop (- n 1)))))))
 	      (display (loop n))
 	      (display s1)
 	      (display ": ")
 	      (display s2)
 	      (newline)))))
-	  
-  (cond
-   ((dns-message? dns-msg) 
-    (begin
-      (d 0 "DNS-MESSAGE" "")
-      (d 1 "QUERY" "")(show-dns-message (dns-message:query dns-msg))(newline)
-      (d 1 "REPLY" "")(show-dns-message (dns-message:reply dns-msg))(newline)
-      (d 1 "CACHE?" (if (dns-message:cache? dns-msg)
-		       "found in cache"
-		       "not found in cache"))
-      (d 1 "PROTOCOL" (let ((protocol (dns-message:protocol dns-msg)))
-			(cond
-			 ((eq? protocol 'tcp) "TCP")
-			 ((eq? protocol 'udp) "UDP"))))
-      (d 1 "TRIED-NAMESERVERS" (if (> (length (dns-message:tried-nameservers dns-msg)) 1)
-				   (begin
-				     (display " had perform recursion: ")
-				     (dns-message:tried-nameservers dns-msg))
-				   (begin
-				     (display " without recursion: ")
-				     (dns-message:tried-nameservers dns-msg))))))
-   ((message? dns-msg)
-    (begin
-      (d 2 "MESSAGE" "")
-      (d 3 "Header     " "")(show-dns-message (message:header dns-msg))
-      (d 3 "Questions  " "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:questions dns-msg))
-      (d 3 "Answers    " "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:answers dns-msg))
-      (d 3 "Nameservers" "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:nameservers dns-msg))
-      (d 3 "Additionals" "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:additionals dns-msg))))
-   ((header? dns-msg)
-    (begin
-      (d 4 "id" (header:id dns-msg))
-      (d 4 "Flags" "")(show-dns-message (header:flags dns-msg))
-      (d 4 "question-count    " (header:qdc dns-msg))
-      (d 4 "answer-count      " (header:anc dns-msg))
-      (d 4 "nameserver-count  " (header:nsc dns-msg))
-      (d 4 "additional-count  " (header:arc dns-msg))))
-   ((flags? dns-msg)
-    (begin 
-      (d 5 "querytype" (flags:querytype dns-msg))
-      (d 5 "opcode" (flags:opcode dns-msg))
-      (d 5 "auth" (flags:auth dns-msg))
-      (d 5 "trunc" (flags:trunc dns-msg))
-      (d 5 "recursiondesired" (flags:recursiondesired dns-msg))
-      (d 5 "recursionavailable" (flags:recursionavailable dns-msg))
-      (d 5 "z" (flags:z dns-msg))
-      (d 5 "rcode" (flags:rcode dns-msg))))
-   ((question? dns-msg)
-    (begin
-      (d 4 "name " (question:name dns-msg))
-      (d 4 "type " (question:type dns-msg))
-      (d 4 "class" (question:class dns-msg))))
-   ((rr? dns-msg)
-    (begin
-      (d 4 "name " (rr:name dns-msg))
-      (d 4 "type " (rr:type dns-msg))
-      (d 4 "class" (rr:class dns-msg))
-      (d 4 "ttl  " (rr:ttl dns-msg))
-      (d 4 "data " "") (show-dns-message (rr:data dns-msg))))
-   ((rr-data-a? dns-msg)
-    (d 5 "ip " (rr-data-a:ip dns-msg)))
-   ((rr-data-ns? dns-msg)
-    (d 5 "name " (rr-data-ns:name dns-msg)))
-   ((rr-data-cname? dns-msg)
-    (d 5 "name " (rr-data-cname:name dns-msg)))
-   ((rr-data-mx? dns-msg)
-    (begin
-      (d 5 "preference " (rr-data-mx:preference dns-msg))
-      (d 5 "exchanger  " (rr-data-mx:exchanger dns-msg))))
-   ((rr-data-ptr? dns-msg) 
-    (d 5 "name " (rr-data-ptr:name dns-msg)))
-   ((rr-data-soa? dns-msg)
-    (begin
-      (d 5 "mname   " (rr-data-soa:mname dns-msg))
-      (d 5 "rname   " (rr-data-soa:rname dns-msg))
-      (d 5 "serial  " (rr-data-soa:serial dns-msg))
-      (d 5 "refresh " (rr-data-soa:refresh dns-msg))
-      (d 5 "expire  " (rr-data-soa:expire dns-msg))
-      (d 5 "minimum " (rr-data-soa:expire dns-msg))))
-;; ###
-   ((rr-data-hinfo? dns-msg)
-    (d 5 "data " (rr-data-hinfo:data dns-msg)))
-   ((rr-data-txt? dns-msg)
-    (d 5 "text " (rr-data-txt:text dns-msg)))
-   ((rr-data-wks? dns-msg)
-    (d 5 "data " (rr-data-wks:data dns-msg)))
-   
-   )))
+    
+    (cond
+     ((dns-message? dns-msg) 
+      (begin
+	(d 0 "DNS-MESSAGE" "")
+	(d 1 "QUERY" "")(show-dns-message (dns-message:query dns-msg))(newline)
+	(d 1 "REPLY" "")(show-dns-message (dns-message:reply dns-msg))(newline)
+	(d 1 "CACHE?" (if (dns-message:cache? dns-msg)
+			  "found in cache"
+			  "not found in cache"))
+	(d 1 "PROTOCOL" (let ((protocol (dns-message:protocol dns-msg)))
+			  (cond
+			   ((eq? protocol 'tcp) "TCP")
+			   ((eq? protocol 'udp) "UDP"))))
+	(d 1 "TRIED-NAMESERVERS" (if (> (length (dns-message:tried-nameservers dns-msg)) 1)
+				     (begin
+				       (display " had perform recursion: ")
+				       (dns-message:tried-nameservers dns-msg))
+				     (begin
+				       (display " without recursion: ")
+				       (dns-message:tried-nameservers dns-msg))))))
+     ((message? dns-msg)
+      (begin
+	(d 2 "MESSAGE" "")
+	(d 3 "Header     " "")(show-dns-message (message:header dns-msg))
+	(d 3 "Questions  " "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:questions dns-msg))
+	(d 3 "Answers    " "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:answers dns-msg))
+	(d 3 "Nameservers" "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:nameservers dns-msg))
+	(d 3 "Additionals" "")(for-each (lambda (x) (show-dns-message x)(newline)) (message:additionals dns-msg))))
+     ((header? dns-msg)
+      (begin
+	(d 4 "id" (header:id dns-msg))
+	(d 4 "Flags" "")(show-dns-message (header:flags dns-msg))
+	(d 4 "question-count    " (header:qdc dns-msg))
+	(d 4 "answer-count      " (header:anc dns-msg))
+	(d 4 "nameserver-count  " (header:nsc dns-msg))
+	(d 4 "additional-count  " (header:arc dns-msg))))
+     ((flags? dns-msg)
+      (begin 
+	(d 5 "querytype" (flags:querytype dns-msg))
+	(d 5 "opcode" (flags:opcode dns-msg))
+	(d 5 "auth" (flags:auth dns-msg))
+	(d 5 "trunc" (flags:trunc dns-msg))
+	(d 5 "recursiondesired" (flags:recursiondesired dns-msg))
+	(d 5 "recursionavailable" (flags:recursionavailable dns-msg))
+	(d 5 "z" (flags:z dns-msg))
+	(d 5 "rcode" (flags:rcode dns-msg))))
+     ((question? dns-msg)
+      (begin
+	(d 4 "name " (question:name dns-msg))
+	(d 4 "type " (question:type dns-msg))
+	(d 4 "class" (question:class dns-msg))))
+     ((rr? dns-msg)
+      (begin
+	(d 4 "name " (rr:name dns-msg))
+	(d 4 "type " (rr:type dns-msg))
+	(d 4 "class" (rr:class dns-msg))
+	(d 4 "ttl  " (rr:ttl dns-msg))
+	(d 4 "data " "") (show-dns-message (rr:data dns-msg))))
+     ((rr-data-a? dns-msg)
+      (d 5 "ip " (rr-data-a:ip dns-msg)))
+     ((rr-data-ns? dns-msg)
+      (d 5 "name " (rr-data-ns:name dns-msg)))
+     ((rr-data-cname? dns-msg)
+      (d 5 "name " (rr-data-cname:name dns-msg)))
+     ((rr-data-mx? dns-msg)
+      (begin
+	(d 5 "preference " (rr-data-mx:preference dns-msg))
+	(d 5 "exchanger  " (rr-data-mx:exchanger dns-msg))))
+     ((rr-data-ptr? dns-msg) 
+      (d 5 "name " (rr-data-ptr:name dns-msg)))
+     ((rr-data-soa? dns-msg)
+      (begin
+	(d 5 "mname   " (rr-data-soa:mname dns-msg))
+	(d 5 "rname   " (rr-data-soa:rname dns-msg))
+	(d 5 "serial  " (rr-data-soa:serial dns-msg))
+	(d 5 "refresh " (rr-data-soa:refresh dns-msg))
+	(d 5 "expire  " (rr-data-soa:expire dns-msg))
+	(d 5 "minimum " (rr-data-soa:expire dns-msg))))
+     ;; ###
+     ((rr-data-hinfo? dns-msg)
+      (d 5 "data " (rr-data-hinfo:data dns-msg)))
+     ((rr-data-txt? dns-msg)
+      (d 5 "text " (rr-data-txt:text dns-msg)))
+     ((rr-data-wks? dns-msg)
+      (d 5 "data " (rr-data-wks:data dns-msg)))
+     
+     )))
diff --git a/modules.scm b/modules.scm
index 685fb3f..0dbc98e 100644
--- a/modules.scm
+++ b/modules.scm
@@ -485,6 +485,8 @@
 	defrec-package
 	random
 	queues
+	conditions
+	handle
 	sort
 	threads
 	locks)