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Posting-Version: version B 2.10.1 6/24/83; site bu-cs.UUCP
Path: utzoo!linus!philabs!cmcl2!seismo!harvard!bu-cs!root
From: root@bu-cs.UUCP (Barry Shein)
Newsgroups: net.lan
Subject: Re: TFTP between IBM-PC, 4.2, Wollongong..
Message-ID: <214@bu-cs.UUCP>
Date: Wed, 6-Mar-85 14:25:25 EST
Article-I.D.: bu-cs.214
Posted: Wed Mar  6 14:25:25 1985
Date-Received: Sat, 9-Mar-85 20:02:56 EST
References: <136@cernvax.UUCP>
Organization: Boston Univ Comp. Sci.
Lines: 27

There was in fact a fix to udp_usrreq.c checksum in 4.2,
if you have a recent release of TWG TCP/IP it should
incorporate this fix and hence your TWG<->4.2 UDP *should*
be broken.

Here is a diff file: (cd /usr/sys/netinet;diff udp_usrreq.c udp_usrreq.orig.c)

2d1
< /*	modified 11/13/84	Boston University	bug in checksum */
35c34
< int	udpcksum = 0;				/* 11/13/84 */
---
> int	udpcksum;
189c188
< 	ui->ui_len = htons((u_short)(len+sizeof(struct udphdr)));/* 11/13/84 */
---
> 	ui->ui_len = len + sizeof (struct udphdr);
194c193
< 	ui->ui_ulen = (u_short)ui->ui_len;	/* 11/13/84  */
---
> 	ui->ui_ulen = htons((u_short)ui->ui_len);


pretty simple, check with TWG about getting a release of their fix
if you don't have it already.

	-Barry Shein, Boston University