Fixing several timeout quirks at tftpd and tftp:

- move TIMEOUT* defines to arpa/tftp.h, as they are used several times
in tftpd and tftp, and the values are part of the RFC definition.
- tftpd and tftp did count the total retransmission time in retries
instead in seconds.  fixed.
- tftpd rexmt timeout was hardcoded by a define and therefore didn't
changed when the timeout option was sent.  fixed.
- limit total retransmission timeout in tftp to also 255 seconds.
- replace obvious atoi()'s by strtonum().
ok claudio@

src/include/arpa/tftp.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: tftp.h,v 1.6 2006/07/20 09:42:44 mglocker Exp $	*/
+/*	$OpenBSD: tftp.h,v 1.7 2006/07/26 09:10:03 mglocker Exp $	*/
 /*	$NetBSD: tftp.h,v 1.3 1994/10/26 00:56:48 cgd Exp $	*/
 
 /*
@@ -41,6 +41,9 @@
 #define	SEGSIZE		512		/* data segment size */
 #define SEGSIZE_MIN	8		/* minimal data segment size */
 #define SEGSIZE_MAX	65464		/* maximal data segment size */
+#define TIMEOUT		5		/* packet rexmt timeout */
+#define TIMEOUT_MIN	1		/* minimal packet rexmt timeout */
+#define TIMEOUT_MAX	255		/* maximal packet rexmt timeout */
 
 /*
  * Packet types.