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Start XIDs at a value based on the current time, not 0. This avoids nasty

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XID confusions with servers that cache them over a long period and
with clients that reboot quickly.

Problems: because of the sanity check that is done by comparing the system
time with filesystem time, XIDs will start at 0 until root is mounted,
which means it isn't completely safe for diskless setups. But it's clearly
better than it was. It would also be cleaner if all XID handling (more
generally, all RPC handling) within the kernel went through the
same functions.
This commit is contained in:
fvdl 1996-07-07 12:23:49 +00:00
parent 63d996d871
commit 88eff7ea92
1 changed files with 18 additions and 1 deletions
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19
sys/nfs/nfs_subs.c
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@ -1,4 +1,4 @@
/* $NetBSD: nfs_subs.c,v 1.29 1996/07/01 10:22:47 fvdl Exp $ */
/* $NetBSD: nfs_subs.c,v 1.30 1996/07/07 12:23:49 fvdl Exp $ */
/*
* Copyright (c) 1989, 1993
@ -55,6 +55,7 @@
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/time.h>
#include <vm/vm.h>
@ -609,6 +610,8 @@ nfsm_rpchead(cr, nmflag, procid, auth_type, auth_len, auth_str, verf_len,
register int i;
struct mbuf *mreq, *mb2;
int siz, grpsiz, authsiz;
struct timeval tv;
static u_int32_t base;
authsiz = nfsm_rndup(auth_len);
MGETHDR(mb, M_WAIT, MT_DATA);
@ -627,8 +630,22 @@ nfsm_rpchead(cr, nmflag, procid, auth_type, auth_len, auth_str, verf_len,
* First the RPC header.
*/
nfsm_build(tl, u_int32_t *, 8 * NFSX_UNSIGNED);
/*
* derive initial xid from system time
* XXX time is invalid if root not yet mounted
*/
if (!base && (rootvp)) {
microtime(&tv);
base = tv.tv_sec << 12;
nfs_xid = base;
}
/*
* Skip zero xid if it should ever happen.
*/
if (++nfs_xid == 0)
nfs_xid++;
*tl++ = *xidp = txdr_unsigned(nfs_xid);
*tl++ = rpc_call;
*tl++ = rpc_vers;