Date: Sun, 7 Apr 1996 00:28:56 -0600 From: Jim Fleming <JimFleming@unety.net> To: "'Jordan K. Hubbard'" <jkh@time.cdrom.com> Subject: Check IP Version Message-ID: <01BB2419.36344C40@webster.unety.net> Resent-Message-ID: <10019.828860751@time.cdrom.com>
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Jordan,
I am starting to develop a substantialliy modified version of the IP protocol.
As specified in the IP protocol the ip_v (IP Version) field of the IP header
should be set to 4. (see /usr/src/sys/netinet/ip.h)
It is not desirable for new versions of IP to "break" existing code. I have not
provide this but in studying the SLIP code I see that there is never really
a check done to see of the IP header is of version 4.
The TCP header is checked as follows...
Line 557 of /usr/src/sys/net/if_sl.c
if ((ip = mtod(m, struct ip *))->ip_p == IPPROTO_TCP) {
I suggest that you might want to change this to...
if ((ip = mtod(m, struct ip *))->ip_v == IPVERSION) && (ip->ip_p == IPPROTO_TCP)) {
...just to make sure...
By the way...I think PPP is OK...I will keep looking...
--
Jim Fleming
UNETY Systems, Inc.
Naperville, IL 60563
e-mail: JimFleming@unety.net
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