From mboxrd@z Thu Jan  1 00:00:00 1970
From: Artem Letko <aletko@iname.com>
Subject: Re: [9fans] fs sntp fix for multiple interfaces
To: 9fans@cse.psu.edu
Message-id: <001501c26adb$3f1ad3a0$1c742544@rosele01.nj.comcast.net>
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References: <3b2aa572be4fd0636f951b8d9df9f9da@collyer.net>
Date: Thu,  3 Oct 2002 08:48:58 -0400
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Shouldn't IP routing take care of this?

Art.

----- Original Message -----
From: "Geoff Collyer" <geoff@collyer.net>
To: <9fans@collyer.net>
Sent: Thursday, October 03, 2002 5:53 AM
Subject: [9fans] fs sntp fix for multiple interfaces


> If you have multiple interfaces, /sys/src/fs/ip/sntp.c transmits on
> the first one on the list of interfaces with a valid IP address, which
> isn't necessarily right.  I've modified it to pick the first interface
> on the same subnet as the SNTP server, if there is such an interface.
> If not, it picks the first interface with a valid default gateway.  If
> there aren't any of those, it gives up.
>
>
> ; history -D sntp.c
> Oct  3 02:36:52 PDT 2002 sntp.c 5564 [geoff]
> sntp.c:146 d /n/dump/2002/1002/sys/src/fs/ip/sntp.c:145
> < /* find an interface on the same subnet as sntpip, if any */
> sntp.c:148,149 c /n/dump/2002/1002/sys/src/fs/ip/sntp.c:147
> < if(isvalidip(ifc->ipa) &&
> <    (nhgetl(ifc->ipa)&ifc->mask) == (nhgetl(sntpip)&ifc->mask))
> ---
> > if(isvalidip(ifc->ipa))
> sntp.c:152 d /n/dump/2002/1002/sys/src/fs/ip/sntp.c:149
> < /* if none, find an interface with a default gateway */
> sntp.c:154,158 d /n/dump/2002/1002/sys/src/fs/ip/sntp.c:150
> < for(ifc = enets; ifc; ifc = ifc->next)
> < if(isvalidip(ifc->ipa) && isvalidip(ifc->netgate))
> < break;
> < if(ifc == nil) {
> < DEBUG("sntp: can't send to %I; no ifc on same subnet or with default
route\n", sntpip);
> sntp.c:160 d /n/dump/2002/1002/sys/src/fs/ip/sntp.c:151
> < }
> sntp.c:163 c /n/dump/2002/1002/sys/src/fs/ip/sntp.c:154
> < DEBUG("sntp: sending to %I on ifc %I\n", sntpip, ifc->ipa);
> ---
> > DEBUG("sntp: sending\n");
> Apr 13 11:10:41 PDT 2002 /n/dump/2002/1002/sys/src/fs/ip/sntp.c 5127
[geoff]
>
>
> So the start of sntpsend should look like this:
>
> void
> sntpsend(void)
> {
> ushort sum;
> Msgbuf *mb;
> Sntppkt *s;
> uchar tmp[Pasize];
> Ifc *ifc;
>
> /* find an interface on the same subnet as sntpip, if any */
> for(ifc = enets; ifc; ifc = ifc->next) {
> if(isvalidip(ifc->ipa) &&
>    (nhgetl(ifc->ipa)&ifc->mask) == (nhgetl(sntpip)&ifc->mask))
> break;
> }
> /* if none, find an interface with a default gateway */
> if(ifc == nil)
> for(ifc = enets; ifc; ifc = ifc->next)
> if(isvalidip(ifc->ipa) && isvalidip(ifc->netgate))
> break;
> if(ifc == nil) {
> DEBUG("sntp: can't send to %I; no ifc on same subnet or with default
route\n", sntpip);
> return;
> }
>
> /* compose a UDP sntp request */
> DEBUG("sntp: sending to %I on ifc %I\n", sntpip, ifc->ipa);