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Date: Thu, 28 May 1998 10:47:17 +0900 (JST)
Message-Id: <199805280147.KAA27100@mail.hitachi-cable.co.jp>
From: Ito Kazumitsu <ito@htk.hitachi-cable.co.jp>
To: FreeBSD-users-jp@jp.freebsd.org
In-reply-to: <199805271418.XAA00857@toto.noc.titech.ac.jp>
	(aki@noc.titech.ac.jp)
References: <199805271100.UAA21568@mail.hitachi-cable.co.jp> <199805271418.XAA00857@toto.noc.titech.ac.jp>
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Subject: [FreeBSD-users-jp 28786] Re: Is IP_DF flag always set to 1?
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From: IIJIMA Akihiro <aki@noc.titech.ac.jp>
Date: Wed, 27 May 1998 23:18:12 +0900

>   > FreeBSD $B$N%^%7%s$+$iAw=P$5$l$k%Q%1%C%H$N(B IP $B%X%C%@$N(B IP_DF $B$,(B
>   > $B>o$K(B 1 $B$K$J$C$F$7$^$&$H$$$&8=>]$KG:$s$G$$$^$9!#(B
>
>   > (/usr/src/sys/netinet/* $B$rD/$a$F$b(B IP_DF $B%S%C%H$r(B 1 $B$K$9$k(B
>   > $B$h$&$J2U=j$O8+$"$?$i$J$$$h$&$J5$$,$9$k$N$G$9$,(B)$B!#(B

$BD/$a$?%=!<%9$O(B FreeBSD 2.1.0-RELEASE $B$N8E$$$b$N$G$7$F!"(B
$B$=$3$K$O8+$"$?$i$J$$$h$&$J5$$,$7$?$N$G$9$,!"(B

>   /sys/netinet/ $B$G(B grep IP_DF $B$9$k$H!"(B
>
>   ip_output.c:            ip->ip_off &= IP_DF;
>   ip_output.c:    if (ip->ip_off & IP_DF) {
>   tcp_output.c:           ((struct ip *)ti)->ip_off |= IP_DF;

$B$3$N(B tcp_output.c $B$N(B |= $B$,2x$7$$$h$&$J5$$,$7$^$9!#(B
FreeBSD 2.1.0-RELEASE $B$K$O4^$^$l$F$$$J$$%3!<%I$G$9!#(B

tcp_output.c $B$NCf$K(B

#if 1
        struct rtentry *rt;
#endif

#if 1
        /*
         * See if we should do MTU discovery.  We do it only if the following
         * are true:
         *      1) we have a valid route to the destination
         *      2) the MTU is not locked (if it is, then discovery has been
         *         disabled)
         */
        if ((rt = tp->t_inpcb->inp_route.ro_rt)
            && rt->rt_flags & RTF_UP
            && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
                ((struct ip *)ti)->ip_off |= IP_DF;
        }
#endif

$B$H$"$j$^$9$,!"$3$N(B #if 1 ... #endif $B$N0U?^$O2?$J$N$G$7$g$&$+!#(B
$B$3$l$r(B #if 0 $B$KJQ99$7$F%3%s%Q%$%k$7$F$bBg>fIW$G$7$g$&$+!#(B

********************
Ito Kazumitsu <ito@htk.hitachi-cable.co.jp>

