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devip: don't send arp requests from null address

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during dhcp, ipconfig assigns the null address :: which makes
ipforme() return Runi for any destination, which can trigger
arp resolution when we attempt to reply. so have v4local()
skip the null address and have sendarp() check the return
status of v4local(), avoing the spurious arp requests.
This commit is contained in:
cinap_lenrek 2018-06-14 00:07:45 +02:00
parent 71ce6f53a4
commit de9141bc6d
2 changed files with 11 additions and 5 deletions
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14
sys/src/9/ip/ethermedium.c
View file

@ -449,6 +449,7 @@ sendarp(Ipifc *ifc, Arpent *a)
Block *bp;
Etherarp *e;
Etherrock *er = ifc->arg;
uchar targ[IPv4addrlen], src[IPv4addrlen];
/* don't do anything if it's been less than a second since the last */
if(NOW - a->ctime < 1000){
@ -456,6 +457,9 @@ sendarp(Ipifc *ifc, Arpent *a)
return;
}
/* try to keep it around for a second more */
a->ctime = NOW;
/* remove all but the last message */
while((bp = a->hold) != nil){
if(bp == a->last)
@ -464,18 +468,20 @@ sendarp(Ipifc *ifc, Arpent *a)
freeblist(bp);
}
/* try to keep it around for a second more */
a->ctime = NOW;
memmove(targ, a->ip+IPv4off, IPv4addrlen);
arprelease(er->f->arp, a);
if(!ipv4local(ifc, src, targ))
return;
n = sizeof(Etherarp);
if(n < ifc->m->mintu)
n = ifc->m->mintu;
bp = allocb(n);
memset(bp->rp, 0, n);
e = (Etherarp*)bp->rp;
memmove(e->tpa, a->ip+IPv4off, sizeof(e->tpa));
ipv4local(ifc, e->spa, e->tpa);
memmove(e->tpa, targ, sizeof(e->tpa));
memmove(e->spa, src, sizeof(e->spa));
memmove(e->sha, ifc->mac, sizeof(e->sha));
memset(e->d, 0xff, sizeof(e->d)); /* ethernet broadcast */
memmove(e->s, ifc->mac, sizeof(e->s));

2
sys/src/9/ip/ipifc.c
View file

@ -1274,7 +1274,7 @@ ipv4local(Ipifc *ifc, uchar *local, uchar *remote)
b = -1;
for(lifc = ifc->lifc; lifc != nil; lifc = lifc->next){
if((lifc->type & Rv4) == 0)
if((lifc->type & Rv4) == 0 || ipcmp(lifc->local, IPnoaddr) == 0)
continue;
a = comprefixlen(lifc->local+IPv4off, remote, IPv4addrlen);
if(a > b){