ref: 83246e296ea433b65b9d295b5e08fedd39ff1ab7
dir: /os/ip/arp.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "ip.h"
#include "ipv6.h"
/*
* address resolution tables
*/
enum
{
NHASH = (1<<6),
NCACHE = 256,
AOK = 1,
AWAIT = 2,
};
char *arpstate[] =
{
"UNUSED",
"OK",
"WAIT",
};
/*
* one per Fs
*/
struct Arp
{
QLock;
Fs *f;
Arpent *hash[NHASH];
Arpent cache[NCACHE];
Arpent *rxmt;
Proc *rxmitp; /* neib sol re-transmit proc */
Rendez rxmtq;
Block *dropf, *dropl;
};
char *Ebadarp = "bad arp";
#define haship(s) ((s)[IPaddrlen-1]%NHASH)
extern int ReTransTimer = RETRANS_TIMER;
static void rxmitproc(void *v);
void
arpinit(Fs *f)
{
f->arp = smalloc(sizeof(Arp));
f->arp->f = f;
f->arp->rxmt = nil;
f->arp->dropf = f->arp->dropl = nil;
kproc("rxmitproc", rxmitproc, f->arp, 0);
}
/*
* create a new arp entry for an ip address.
*/
static Arpent*
newarp6(Arp *arp, uchar *ip, Ipifc *ifc, int addrxt)
{
uint t;
Block *next, *xp;
Arpent *a, *e, *f, **l;
Medium *m = ifc->m;
int empty;
/* find oldest entry */
e = &arp->cache[NCACHE];
a = arp->cache;
t = a->utime;
for(f = a; f < e; f++){
if(f->utime < t){
t = f->utime;
a = f;
}
}
/* dump waiting packets */
xp = a->hold;
a->hold = nil;
if(isv4(a->ip)){
while(xp){
next = xp->list;
freeblist(xp);
xp = next;
}
}
else { // queue icmp unreachable for rxmitproc later on, w/o arp lock
if(xp){
if(arp->dropl == nil)
arp->dropf = xp;
else
arp->dropl->list = xp;
for(next = xp->list; next; next = next->list)
xp = next;
arp->dropl = xp;
wakeup(&arp->rxmtq);
}
}
/* take out of current chain */
l = &arp->hash[haship(a->ip)];
for(f = *l; f; f = f->hash){
if(f == a){
*l = a->hash;
break;
}
l = &f->hash;
}
/* insert into new chain */
l = &arp->hash[haship(ip)];
a->hash = *l;
*l = a;
memmove(a->ip, ip, sizeof(a->ip));
a->utime = NOW;
a->ctime = 0;
a->type = m;
a->rtime = NOW + ReTransTimer;
a->rxtsrem = MAX_MULTICAST_SOLICIT;
a->ifc = ifc;
a->ifcid = ifc->ifcid;
/* put to the end of re-transmit chain; addrxt is 0 when isv4(a->ip) */
if(!ipismulticast(a->ip) && addrxt){
l = &arp->rxmt;
empty = (*l==nil);
for(f = *l; f; f = f->nextrxt){
if(f == a){
*l = a->nextrxt;
break;
}
l = &f->nextrxt;
}
for(f = *l; f; f = f->nextrxt){
l = &f->nextrxt;
}
*l = a;
if(empty)
wakeup(&arp->rxmtq);
}
a->nextrxt = nil;
return a;
}
/* called with arp qlocked */
void
cleanarpent(Arp *arp, Arpent *a)
{
Arpent *f, **l;
a->utime = 0;
a->ctime = 0;
a->type = 0;
a->state = 0;
/* take out of current chain */
l = &arp->hash[haship(a->ip)];
for(f = *l; f; f = f->hash){
if(f == a){
*l = a->hash;
break;
}
l = &f->hash;
}
/* take out of re-transmit chain */
l = &arp->rxmt;
for(f = *l; f; f = f->nextrxt){
if(f == a){
*l = a->nextrxt;
break;
}
l = &f->nextrxt;
}
a->nextrxt = nil;
a->hash = nil;
a->hold = nil;
a->last = nil;
a->ifc = nil;
}
/*
* fill in the media address if we have it. Otherwise return an
* Arpent that represents the state of the address resolution FSM
* for ip. Add the packet to be sent onto the list of packets
* waiting for ip->mac to be resolved.
*/
Arpent*
arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac)
{
int hash;
Arpent *a;
Medium *type = ifc->m;
uchar v6ip[IPaddrlen];
if(version == V4){
v4tov6(v6ip, ip);
ip = v6ip;
}
qlock(arp);
hash = haship(ip);
for(a = arp->hash[hash]; a; a = a->hash){
if(memcmp(ip, a->ip, sizeof(a->ip)) == 0)
if(type == a->type)
break;
}
if(a == nil){
a = newarp6(arp, ip, ifc, (version != V4));
a->state = AWAIT;
}
a->utime = NOW;
if(a->state == AWAIT){
if(bp != nil){
if(a->hold)
a->last->list = bp;
else
a->hold = bp;
a->last = bp;
bp->list = nil;
}
return a; /* return with arp qlocked */
}
memmove(mac, a->mac, a->type->maclen);
/* remove old entries */
if(NOW - a->ctime > 15*60*1000)
cleanarpent(arp, a);
qunlock(arp);
return nil;
}
/*
* called with arp locked
*/
void
arprelease(Arp *arp, Arpent*)
{
qunlock(arp);
}
/*
* Copy out the mac address from the Arpent. Return the
* block waiting to get sent to this mac address.
*
* called with arp locked
*/
Block*
arpresolve(Arp *arp, Arpent *a, Medium *type, uchar *mac)
{
Block *bp;
Arpent *f, **l;
if(!isv4(a->ip)){
l = &arp->rxmt;
for(f = *l; f; f = f->nextrxt){
if(f == a){
*l = a->nextrxt;
break;
}
l = &f->nextrxt;
}
}
memmove(a->mac, mac, type->maclen);
a->type = type;
a->state = AOK;
a->utime = NOW;
bp = a->hold;
a->hold = nil;
qunlock(arp);
return bp;
}
void
arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, int refresh)
{
Arp *arp;
Route *r;
Arpent *a, *f, **l;
Ipifc *ifc;
Medium *type;
Block *bp, *next;
uchar v6ip[IPaddrlen];
arp = fs->arp;
if(n != 6){
// print("arp: len = %d\n", n);
return;
}
switch(version){
case V4:
r = v4lookup(fs, ip, nil);
v4tov6(v6ip, ip);
ip = v6ip;
break;
case V6:
r = v6lookup(fs, ip, nil);
break;
default:
panic("arpenter: version %d", version);
return; /* to supress warnings */
}
if(r == nil){
// print("arp: no route for entry\n");
return;
}
ifc = r->ifc;
type = ifc->m;
qlock(arp);
for(a = arp->hash[haship(ip)]; a; a = a->hash){
if(a->type != type || (a->state != AWAIT && a->state != AOK))
continue;
if(ipcmp(a->ip, ip) == 0){
a->state = AOK;
memmove(a->mac, mac, type->maclen);
if(version == V6){
/* take out of re-transmit chain */
l = &arp->rxmt;
for(f = *l; f; f = f->nextrxt){
if(f == a){
*l = a->nextrxt;
break;
}
l = &f->nextrxt;
}
}
a->ifc = ifc;
a->ifcid = ifc->ifcid;
bp = a->hold;
a->hold = nil;
if(version == V4)
ip += IPv4off;
a->utime = NOW;
a->ctime = a->utime;
qunlock(arp);
while(bp){
next = bp->list;
if(ifc != nil){
if(waserror()){
runlock(ifc);
nexterror();
}
rlock(ifc);
if(ifc->m != nil)
ifc->m->bwrite(ifc, bp, version, ip);
else
freeb(bp);
runlock(ifc);
poperror();
} else
freeb(bp);
bp = next;
}
return;
}
}
if(refresh == 0){
a = newarp6(arp, ip, ifc, 0);
a->state = AOK;
a->type = type;
a->ctime = NOW;
memmove(a->mac, mac, type->maclen);
}
qunlock(arp);
}
int
arpwrite(Fs *fs, char *s, int len)
{
int n;
Route *r;
Arp *arp;
Block *bp;
Arpent *a, *fl, **l;
Medium *m;
char *f[4], buf[256];
uchar ip[IPaddrlen], mac[MAClen];
arp = fs->arp;
if(len == 0)
error(Ebadarp);
if(len >= sizeof(buf))
len = sizeof(buf)-1;
strncpy(buf, s, len);
buf[len] = 0;
if(len > 0 && buf[len-1] == '\n')
buf[len-1] = 0;
n = getfields(buf, f, 4, 1, " ");
if(strcmp(f[0], "flush") == 0){
qlock(arp);
for(a = arp->cache; a < &arp->cache[NCACHE]; a++){
memset(a->ip, 0, sizeof(a->ip));
memset(a->mac, 0, sizeof(a->mac));
a->hash = nil;
a->state = 0;
a->utime = 0;
while(a->hold != nil){
bp = a->hold->list;
freeblist(a->hold);
a->hold = bp;
}
}
memset(arp->hash, 0, sizeof(arp->hash));
// clear all pkts on these lists (rxmt, dropf/l)
arp->rxmt = nil;
arp->dropf = nil;
arp->dropl = nil;
qunlock(arp);
} else if(strcmp(f[0], "add") == 0){
switch(n){
default:
error(Ebadarg);
case 3:
parseip(ip, f[1]);
if(isv4(ip))
r = v4lookup(fs, ip+IPv4off, nil);
else
r = v6lookup(fs, ip, nil);
if(r == nil)
error("Destination unreachable");
m = r->ifc->m;
n = parsemac(mac, f[2], m->maclen);
break;
case 4:
m = ipfindmedium(f[1]);
if(m == nil)
error(Ebadarp);
parseip(ip, f[2]);
n = parsemac(mac, f[3], m->maclen);
break;
}
if(m->ares == nil)
error(Ebadarp);
m->ares(fs, V6, ip, mac, n, 0);
} else if(strcmp(f[0], "del") == 0){
if(n != 2)
error(Ebadarg);
parseip(ip, f[1]);
qlock(arp);
l = &arp->hash[haship(ip)];
for(a = *l; a; a = a->hash){
if(memcmp(ip, a->ip, sizeof(a->ip)) == 0){
*l = a->hash;
break;
}
l = &a->hash;
}
if(a){
/* take out of re-transmit chain */
l = &arp->rxmt;
for(fl = *l; fl; fl = fl->nextrxt){
if(fl == a){
*l = a->nextrxt;
break;
}
l = &fl->nextrxt;
}
a->nextrxt = nil;
a->hash = nil;
a->hold = nil;
a->last = nil;
a->ifc = nil;
memset(a->ip, 0, sizeof(a->ip));
memset(a->mac, 0, sizeof(a->mac));
}
qunlock(arp);
} else
error(Ebadarp);
return len;
}
enum
{
Alinelen= 90,
};
char *aformat = "%-6.6s %-8.8s %-40.40I %-32.32s\n";
static void
convmac(char *p, uchar *mac, int n)
{
while(n-- > 0)
p += sprint(p, "%2.2ux", *mac++);
}
int
arpread(Arp *arp, char *p, ulong offset, int len)
{
Arpent *a;
int n;
char mac[2*MAClen+1];
if(offset % Alinelen)
return 0;
offset = offset/Alinelen;
len = len/Alinelen;
n = 0;
for(a = arp->cache; len > 0 && a < &arp->cache[NCACHE]; a++){
if(a->state == 0)
continue;
if(offset > 0){
offset--;
continue;
}
len--;
qlock(arp);
convmac(mac, a->mac, a->type->maclen);
n += sprint(p+n, aformat, a->type->name, arpstate[a->state], a->ip, mac);
qunlock(arp);
}
return n;
}
extern int
rxmitsols(Arp *arp)
{
uint sflag;
Block *next, *xp;
Arpent *a, *b, **l;
Fs *f;
uchar ipsrc[IPaddrlen];
Ipifc *ifc = nil;
long nrxt;
qlock(arp);
f = arp->f;
a = arp->rxmt;
if(a==nil){
nrxt = 0;
goto dodrops; //return nrxt;
}
nrxt = a->rtime - NOW;
if(nrxt > 3*ReTransTimer/4)
goto dodrops; //return nrxt;
for(; a; a = a->nextrxt){
ifc = a->ifc;
assert(ifc != nil);
if((a->rxtsrem <= 0) || !(canrlock(ifc)) || (a->ifcid != ifc->ifcid)){
xp = a->hold;
a->hold = nil;
if(xp){
if(arp->dropl == nil)
arp->dropf = xp;
else
arp->dropl->list = xp;
}
cleanarpent(arp, a);
}
else
break;
}
if(a == nil)
goto dodrops;
qunlock(arp); /* for icmpns */
if((sflag = ipv6anylocal(ifc, ipsrc)) != SRC_UNSPEC)
icmpns(f, ipsrc, sflag, a->ip, TARG_MULTI, ifc->mac);
runlock(ifc);
qlock(arp);
/* put to the end of re-transmit chain */
l = &arp->rxmt;
for(b = *l; b; b = b->nextrxt){
if(b == a){
*l = a->nextrxt;
break;
}
l = &b->nextrxt;
}
for(b = *l; b; b = b->nextrxt){
l = &b->nextrxt;
}
*l = a;
a->rxtsrem--;
a->nextrxt = nil;
a->rtime = NOW + ReTransTimer;
a = arp->rxmt;
if(a==nil)
nrxt = 0;
else
nrxt = a->rtime - NOW;
dodrops:
xp = arp->dropf;
arp->dropf = nil;
arp->dropl = nil;
qunlock(arp);
for(; xp; xp = next){
next = xp->list;
icmphostunr(f, ifc, xp, icmp6_adr_unreach, 1);
}
return nrxt;
}
static int
rxready(void *v)
{
Arp *arp = (Arp *) v;
int x;
x = ((arp->rxmt != nil) || (arp->dropf != nil));
return x;
}
static void
rxmitproc(void *v)
{
Arp *arp = v;
long wakeupat;
arp->rxmitp = up;
//print("arp rxmitproc started\n");
if(waserror()){
arp->rxmitp = 0;
pexit("hangup", 1);
}
for(;;){
wakeupat = rxmitsols(arp);
if(wakeupat == 0)
sleep(&arp->rxmtq, rxready, v);
else if(wakeupat > ReTransTimer/4)
tsleep(&arp->rxmtq, return0, 0, wakeupat);
}
}