34890f9dd9
idea. This is les likely to crash your machine. As before, this code is only enabled under `options IN_RMX'.
159 lines
4.0 KiB
C
159 lines
4.0 KiB
C
/*
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* Copyright 1994, Massachusetts Institute of Technology. All Rights Reserved.
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*
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* You may copy this file verbatim until I find the official
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* Institute boilerplate.
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*
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* $Id: in_rmx.c,v 1.1 1994/11/02 04:42:14 wollman Exp $
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*/
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/*
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* This code does two things necessary for the enhanced TCP metrics to
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* function in a useful manner:
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* 1) It marks all non-host routes as `cloning', thus ensuring that
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* every actual reference to such a route actually gets turned
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* into a reference to a host route to the specific destination
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* requested.
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* 2) When such routes lose all their references, it arranges for them
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* to be deleted in some random collection of circumstances, so that
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* a large quantity of stale routing data is not kept in kernel memory
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* indefinitely. See in_rtqtimo() below for the exact mechanism.
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*
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* At least initially, we think that this should have lower overhead than
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* using the existing `expire' mechanism and walking the radix tree
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* periodically, deleting things as we go. That method would be relatively
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* easy to implement within the framework used here, and in the future
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* we made code both ways, so that folks with large routing tables can use
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* the external queue, and the majority with small routing tables can do
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* the tree-walk.
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*/
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/*
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* XXX - look for races
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/queue.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/mbuf.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#define RTPRF_OURS 0x10000 /* set on routes we manage */
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/*
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* Do what we need to do when inserting a route.
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*/
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static struct radix_node *
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in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
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struct radix_node *treenodes)
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{
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struct rtentry *rt = (struct rtentry *)treenodes;
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struct in_rtq *inr;
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/*
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* For IP, all non-host routes are automatically cloning.
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*/
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if(!(rt->rt_flags & RTF_HOST))
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rt->rt_flags |= RTF_CLONING;
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return rn_addroute(v_arg, n_arg, head, treenodes);
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}
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/*
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* This code is the inverse of in_clsroute: on first reference, if we
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* were managing the route, stop doing so and set the expiration timer
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* back off again.
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*/
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static struct radix_node *
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in_matroute(void *v_arg, struct radix_node_head *head)
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{
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struct radix_node *rn = rn_match(v_arg, head);
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struct rtentry *rt = (struct rtentry *)rn;
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if(rt && rt->rt_refcnt == 0) { /* this is first reference */
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if(rt->rt_prflags & RTPRF_OURS) {
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rt->rt_prflags &= ~RTPRF_OURS;
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rt->rt_rmx.rmx_expire = 0;
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}
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}
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return rn;
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}
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#define RTQ_REALLYOLD 4*60*60 /* four hours is ``really old'' */
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/*
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* On last reference drop, add the route to the queue so that it can be
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* timed out.
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*/
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static void
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in_clsroute(struct radix_node *rn, struct radix_node_head *head)
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{
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struct rtentry *rt = (struct rtentry *)rn;
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struct in_rtq *inr;
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if((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
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return;
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if((rt->rt_prflags & (RTPRF_WASCLONED | RTPRF_OURS))
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!= RTPRF_WASCLONED)
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return;
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rt->rt_prflags |= RTPRF_OURS;
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rt->rt_rmx.rmx_expire = time.tv_sec + RTQ_REALLYOLD;
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}
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/*
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* Get rid of everything in the queue, we are short on memory.
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* Although this looks like an infinite loop, it really isn't;
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* rtrequest() eventually calls in_delroute() which ends up deleting
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* the node at the head (or so we hope). This should be called from
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* ip_drain().
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*/
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void
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in_rtqdrain(void)
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{
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/* write me! */
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;
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}
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#define RTQ_TIMEOUT (60*hz) /* run once a minute */
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/*
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* Get rid of old routes.
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*/
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static void
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in_rtqtimo(void *rock)
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{
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/* write me! */
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timeout(in_rtqtimo, rock, RTQ_TIMEOUT);
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}
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/*
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* Initialize our routing tree.
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*/
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int
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in_inithead(void **head, int off)
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{
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struct radix_node_head *rnh;
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if(!rn_inithead(head, off))
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return 0;
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rnh = *head;
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rnh->rnh_addaddr = in_addroute;
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rnh->rnh_matchaddr = in_matroute;
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rnh->rnh_close = in_clsroute;
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in_rtqtimo(rnh); /* kick off timeout first time */
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return 1;
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}
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