Date: Thu, 25 Jul 2002 00:24:21 -0700 From: "Qing Li" <Qing.Li@windriver.com> To: "FreeBSD-Hackers" <hackers@freebsd.org> Subject: questions about some code in route.c Message-ID: <DMEGKJAJNLKBGDDBEAIPEEGGFMAA.Qing.Li@windriver.com>
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Please help me try to understand some of the code in route.c.
1. In function "rtrequest1",
=========================================
case RTM_DELETE:
<snip>
/*
* Now search what's left of the subtree for any cloned
* routes which might have been formed from this node.
*/
if ((rt->rt_flags & (RTF_CLONING | RTF_PRCLONING)) &&
rt_mask(rt)) {
<snip>
=========================================
Question: under what situation would a route entry that is
clone-able but having a (rt_mask(rt) == 0) ??
2. A related question is, in the same function,
=========================================
<snip>
/*
* We repeat the same procedure from rt_setgate() here because
* it doesn't fire when we call it there because the node
* hasn't been added to the tree yet.
*/
if (!(rt->rt_flags & RTF_HOST) && rt_mask(rt) != 0) {
struct rtfc_arg arg;
arg.rnh = rnh;
arg.rt0 = rt;
rnh->rnh_walktree_from(rnh, rt_key(rt), rt_mask(rt),
rt_fixchange, &arg);
}
<snip>
=========================================
Question: wouldn't the 1st check for "not a host route" be
sufficient ??
3. In function "rtredirect",
==========================================
<snip>
/*
* Create a new entry if we just got back a wildcard entry
* or the the lookup failed. This is necessary for hosts
* which use routing redirects generated by smart gateways
* to dynamically build the routing tables.
*/
if ((rt == 0) || (rt_mask(rt) && rt_mask(rt)->sa_len < 2))
goto create;
<snip>
============================================
Question:
I am guessing (sa_len < 2) is checking for a mask of
all 0's based on what in_socktrim does, is this correct ??
Why is the magic number "2" ?
Any help/pointer on these would be greatly appreciated.
-- Qing
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