ref: c739f57ac2f136e67be63a4678d4171889057105
dir: /sys/src/9/port/devbridge.c/
/*
* IP Ethernet bridge
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../ip/ip.h"
#include "../ip/ipv6.h"
#include "../port/netif.h"
#include "../port/error.h"
typedef struct Bridge Bridge;
typedef struct Port Port;
typedef struct Centry Centry;
typedef struct Tcphdr Tcphdr;
enum
{
Qtopdir= 1, /* top level directory */
Qbridgedir, /* bridge* directory */
Qbctl,
Qstats,
Qcache,
Qlog,
Qportdir, /* directory for a protocol */
Qpctl,
Qlocal,
Qstatus,
MaxQ,
Maxbridge= 4,
Maxport= 128, // power of 2
CacheHash= 257, // prime
CacheLook= 5, // how many cache entries to examine
CacheSize= (CacheHash+CacheLook-1),
CacheTimeout= 5*60, // timeout for cache entry in seconds
MaxMTU= IP_MAX, // allow for jumbo frames and large UDP
TcpMssMax = 1300, // max desirable Tcp MSS value
TunnelMtu = 1400,
};
static Dirtab bridgedirtab[]={
"ctl", {Qbctl}, 0, 0666,
"stats", {Qstats}, 0, 0444,
"cache", {Qcache}, 0, 0444,
"log", {Qlog}, 0, 0666,
};
static Dirtab portdirtab[]={
"ctl", {Qpctl}, 0, 0666,
"local", {Qlocal}, 0, 0444,
"status", {Qstatus}, 0, 0444,
};
enum {
Logcache= (1<<0),
Logmcast= (1<<1),
};
// types of interfaces
enum
{
Tether,
Ttun,
};
static Logflag logflags[] =
{
{ "cache", Logcache, },
{ "multicast", Logmcast, },
{ nil, 0, },
};
static Dirtab *dirtab[MaxQ];
#define TYPE(x) (((ulong)(x).path) & 0xff)
#define PORT(x) ((((ulong)(x).path) >> 8)&(Maxport-1))
#define QID(x, y) (((x)<<8) | (y))
struct Centry
{
uchar d[Eaddrlen];
int port;
long expire; // entry expires this many seconds after bootime
long src;
long dst;
};
struct Bridge
{
QLock;
int nport;
Port *port[Maxport];
Centry cache[CacheSize];
ulong hit;
ulong miss;
ulong copy;
long delay0; // constant microsecond delay per packet
long delayn; // microsecond delay per byte
int tcpmss; // modify tcpmss value
Log;
};
struct Port
{
Ref;
int id;
Bridge *bridge;
int closed;
Chan *data[2]; // channel to data
Proc *readp; // read proc
// the following uniquely identifies the port
int type;
char name[KNAMELEN];
// owner hash - avoids bind/unbind races
ulong ownhash;
// various stats
int in; // number of packets read
int inmulti; // multicast or broadcast
int inunknown; // unknown address
int out; // number of packets read
int outmulti; // multicast or broadcast
int outunknown; // unknown address
int outfrag; // fragmented the packet
int nentry; // number of cache entries for this port
};
enum {
EOLOPT = 0,
NOOPOPT = 1,
MSSOPT = 2,
MSS_LENGTH = 4, /* Mean segment size */
SYN = 0x02, /* Pkt. is synchronise */
TCPHDR = 20,
};
struct Tcphdr
{
uchar sport[2];
uchar dport[2];
uchar seq[4];
uchar ack[4];
uchar flag[2];
uchar win[2];
uchar cksum[2];
uchar urg[2];
};
static Bridge bridgetab[Maxbridge];
static int m2p[] = {
[OREAD] 4,
[OWRITE] 2,
[ORDWR] 6
};
static int bridgegen(Chan *c, char*, Dirtab*, int, int s, Dir *dp);
static void portbind(Bridge *b, int argc, char *argv[]);
static void portunbind(Bridge *b, int argc, char *argv[]);
static void etherread(void *a);
static char *cachedump(Bridge *b);
static void portfree(Port *port);
static void cacheflushport(Bridge *b, int port);
static void etherwrite(Port *port, Block *bp);
static void
bridgeinit(void)
{
int i;
Dirtab *dt;
// setup dirtab with non directory entries
for(i=0; i<nelem(bridgedirtab); i++) {
dt = bridgedirtab + i;
dirtab[TYPE(dt->qid)] = dt;
}
for(i=0; i<nelem(portdirtab); i++) {
dt = portdirtab + i;
dirtab[TYPE(dt->qid)] = dt;
}
}
static Chan*
bridgeattach(char *spec)
{
Chan *c;
ulong dev;
dev = strtoul(spec, nil, 10);
if(dev >= Maxbridge)
error(Enodev);
c = devattach('B', spec);
mkqid(&c->qid, QID(0, Qtopdir), 0, QTDIR);
c->dev = dev;
return c;
}
static Walkqid*
bridgewalk(Chan *c, Chan *nc, char **name, int nname)
{
return devwalk(c, nc, name, nname, (Dirtab*)0, 0, bridgegen);
}
static int
bridgestat(Chan* c, uchar* db, int n)
{
return devstat(c, db, n, (Dirtab *)0, 0L, bridgegen);
}
static Chan*
bridgeopen(Chan* c, int omode)
{
int perm;
Bridge *b;
omode &= 3;
perm = m2p[omode];
USED(perm);
b = bridgetab + c->dev;
USED(b);
switch(TYPE(c->qid)) {
default:
break;
case Qlog:
logopen(b);
break;
case Qcache:
c->aux = cachedump(b);
break;
}
c->mode = openmode(omode);
c->flag |= COPEN;
c->offset = 0;
return c;
}
static void
bridgeclose(Chan* c)
{
Bridge *b = bridgetab + c->dev;
switch(TYPE(c->qid)) {
case Qcache:
if(c->flag & COPEN)
free(c->aux);
break;
case Qlog:
if(c->flag & COPEN)
logclose(b);
break;
}
}
static long
bridgeread(Chan *c, void *a, long n, vlong off)
{
char buf[256];
Bridge *b = bridgetab + c->dev;
Port *port;
int i, ingood, outgood;
USED(off);
switch(TYPE(c->qid)) {
default:
error(Egreg);
case Qtopdir:
case Qbridgedir:
case Qportdir:
return devdirread(c, a, n, 0, 0, bridgegen);
case Qlog:
return logread(b, a, off, n);
case Qlocal:
return 0; /* TO DO */
case Qstatus:
qlock(b);
if(waserror()){
qunlock(b);
nexterror();
}
port = b->port[PORT(c->qid)];
if(port == 0)
strcpy(buf, "unbound\n");
else {
i = 0;
switch(port->type) {
default:
panic("bridgeread: unknown port type: %d",
port->type);
case Tether:
i += snprint(buf+i, sizeof(buf)-i, "ether %s: ", port->name);
break;
case Ttun:
i += snprint(buf+i, sizeof(buf)-i, "tunnel %s: ", port->name);
break;
}
ingood = port->in - port->inmulti - port->inunknown;
outgood = port->out - port->outmulti - port->outunknown;
snprint(buf+i, sizeof(buf)-i,
"in=%d(%d:%d:%d) out=%d(%d:%d:%d:%d)\n",
port->in, ingood, port->inmulti, port->inunknown,
port->out, outgood, port->outmulti,
port->outunknown, port->outfrag);
}
poperror();
qunlock(b);
return readstr(off, a, n, buf);
case Qbctl:
snprint(buf, sizeof(buf), "%s tcpmss\ndelay %ld %ld\n",
b->tcpmss ? "set" : "clear", b->delay0, b->delayn);
n = readstr(off, a, n, buf);
return n;
case Qcache:
n = readstr(off, a, n, c->aux);
return n;
case Qstats:
snprint(buf, sizeof(buf), "hit=%uld miss=%uld copy=%uld\n",
b->hit, b->miss, b->copy);
n = readstr(off, a, n, buf);
return n;
}
}
static void
bridgeoption(Bridge *b, char *option, int value)
{
if(strcmp(option, "tcpmss") == 0)
b->tcpmss = value;
else
error("unknown bridge option");
}
static long
bridgewrite(Chan *c, void *a, long n, vlong off)
{
Bridge *b = bridgetab + c->dev;
Cmdbuf *cb;
char *arg0, *p;
USED(off);
switch(TYPE(c->qid)) {
default:
error(Eperm);
case Qbctl:
cb = parsecmd(a, n);
qlock(b);
if(waserror()) {
qunlock(b);
free(cb);
nexterror();
}
if(cb->nf == 0)
error("short write");
arg0 = cb->f[0];
if(strcmp(arg0, "bind") == 0) {
portbind(b, cb->nf-1, cb->f+1);
} else if(strcmp(arg0, "unbind") == 0) {
portunbind(b, cb->nf-1, cb->f+1);
} else if(strcmp(arg0, "cacheflush") == 0) {
log(b, Logcache, "cache flush\n");
memset(b->cache, 0, CacheSize*sizeof(Centry));
} else if(strcmp(arg0, "set") == 0) {
if(cb->nf != 2)
error("usage: set option");
bridgeoption(b, cb->f[1], 1);
} else if(strcmp(arg0, "clear") == 0) {
if(cb->nf != 2)
error("usage: clear option");
bridgeoption(b, cb->f[1], 0);
} else if(strcmp(arg0, "delay") == 0) {
if(cb->nf != 3)
error("usage: delay delay0 delayn");
b->delay0 = strtol(cb->f[1], nil, 10);
b->delayn = strtol(cb->f[2], nil, 10);
} else
error("unknown control request");
poperror();
qunlock(b);
free(cb);
return n;
case Qlog:
cb = parsecmd(a, n);
p = logctl(b, cb->nf, cb->f, logflags);
free(cb);
if(p != nil)
error(p);
return n;
}
}
static int
bridgegen(Chan *c, char *, Dirtab*, int, int s, Dir *dp)
{
Bridge *b = bridgetab + c->dev;
int type = TYPE(c->qid);
Dirtab *dt;
Qid qid;
if(s == DEVDOTDOT){
switch(TYPE(c->qid)){
case Qtopdir:
case Qbridgedir:
snprint(up->genbuf, sizeof(up->genbuf), "#B%ld", c->dev);
mkqid(&qid, Qtopdir, 0, QTDIR);
devdir(c, qid, up->genbuf, 0, eve, 0555, dp);
break;
case Qportdir:
snprint(up->genbuf, sizeof(up->genbuf), "bridge%ld", c->dev);
mkqid(&qid, Qbridgedir, 0, QTDIR);
devdir(c, qid, up->genbuf, 0, eve, 0555, dp);
break;
default:
panic("bridgewalk %llux", c->qid.path);
}
return 1;
}
switch(type) {
default:
/* non-directory entries end up here */
if(c->qid.type & QTDIR)
panic("bridgegen: unexpected directory");
if(s != 0)
return -1;
dt = dirtab[TYPE(c->qid)];
if(dt == nil)
panic("bridgegen: unknown type: %lud", TYPE(c->qid));
devdir(c, c->qid, dt->name, dt->length, eve, dt->perm, dp);
return 1;
case Qtopdir:
if(s != 0)
return -1;
snprint(up->genbuf, sizeof(up->genbuf), "bridge%ld", c->dev);
mkqid(&qid, QID(0, Qbridgedir), 0, QTDIR);
devdir(c, qid, up->genbuf, 0, eve, 0555, dp);
return 1;
case Qbridgedir:
if(s<nelem(bridgedirtab)) {
dt = bridgedirtab+s;
devdir(c, dt->qid, dt->name, dt->length, eve, dt->perm, dp);
return 1;
}
s -= nelem(bridgedirtab);
if(s >= b->nport)
return -1;
mkqid(&qid, QID(s, Qportdir), 0, QTDIR);
snprint(up->genbuf, sizeof(up->genbuf), "%d", s);
devdir(c, qid, up->genbuf, 0, eve, 0555, dp);
return 1;
case Qportdir:
if(s>=nelem(portdirtab))
return -1;
dt = portdirtab+s;
mkqid(&qid, QID(PORT(c->qid),TYPE(dt->qid)), 0, QTFILE);
devdir(c, qid, dt->name, dt->length, eve, dt->perm, dp);
return 1;
}
}
// parse mac address; also in netif.c
static int
parseaddr(uchar *to, char *from, int alen)
{
char nip[4];
char *p;
int i;
p = from;
for(i = 0; i < alen; i++){
if(*p == 0)
return -1;
nip[0] = *p++;
if(*p == 0)
return -1;
nip[1] = *p++;
nip[2] = 0;
to[i] = strtoul(nip, 0, 16);
if(*p == ':')
p++;
}
return 0;
}
// assumes b is locked
static void
portbind(Bridge *b, int argc, char *argv[])
{
Port *port;
Chan *ctl;
int type = 0, i, n;
ulong ownhash;
char *dev, *dev2 = nil;
char buf[100], name[KNAMELEN], path[8*KNAMELEN];
static char usage[] = "usage: bind ether|tunnel name ownhash dev [dev2]";
memset(name, 0, KNAMELEN);
if(argc < 4)
error(usage);
if(strcmp(argv[0], "ether") == 0) {
if(argc != 4)
error(usage);
type = Tether;
strncpy(name, argv[1], KNAMELEN);
name[KNAMELEN-1] = 0;
// parseaddr(addr, argv[1], Eaddrlen);
} else if(strcmp(argv[0], "tunnel") == 0) {
if(argc != 5)
error(usage);
type = Ttun;
strncpy(name, argv[1], KNAMELEN);
name[KNAMELEN-1] = 0;
// parseip(addr, argv[1]);
dev2 = argv[4];
} else
error(usage);
ownhash = atoi(argv[2]);
dev = argv[3];
for(i=0; i<b->nport; i++) {
port = b->port[i];
if(port != nil && port->type == type &&
memcmp(port->name, name, KNAMELEN) == 0)
error("port in use");
}
for(i=0; i<Maxport; i++)
if(b->port[i] == nil)
break;
if(i == Maxport)
error("no more ports");
port = smalloc(sizeof(Port));
port->ref = 1;
port->id = i;
port->ownhash = ownhash;
if(waserror()) {
portfree(port);
nexterror();
}
port->type = type;
memmove(port->name, name, KNAMELEN);
switch(port->type) {
default:
panic("portbind: unknown port type: %d", type);
case Tether:
snprint(path, sizeof(path), "%s/clone", dev);
ctl = namec(path, Aopen, ORDWR, 0);
if(waserror()) {
cclose(ctl);
nexterror();
}
// check addr?
// get directory name
n = devtab[ctl->type]->read(ctl, buf, sizeof(buf)-1, 0);
buf[n] = 0;
snprint(path, sizeof(path), "%s/%lud/data", dev, strtoul(buf, 0, 0));
// setup connection to be promiscuous
snprint(buf, sizeof(buf), "connect -1");
devtab[ctl->type]->write(ctl, buf, strlen(buf), 0);
snprint(buf, sizeof(buf), "nonblocking");
devtab[ctl->type]->write(ctl, buf, strlen(buf), 0);
snprint(buf, sizeof(buf), "promiscuous");
devtab[ctl->type]->write(ctl, buf, strlen(buf), 0);
snprint(buf, sizeof(buf), "bridge");
devtab[ctl->type]->write(ctl, buf, strlen(buf), 0);
// open data port
port->data[0] = namec(path, Aopen, ORDWR, 0);
// dup it
incref(port->data[0]);
port->data[1] = port->data[0];
poperror();
cclose(ctl);
break;
case Ttun:
port->data[0] = namec(dev, Aopen, OREAD, 0);
port->data[1] = namec(dev2, Aopen, OWRITE, 0);
break;
}
poperror();
/* committed to binding port */
b->port[port->id] = port;
port->bridge = b;
if(b->nport <= port->id)
b->nport = port->id+1;
// assumes kproc always succeeds
incref(port);
snprint(buf, sizeof(buf), "bridge:%s", dev);
kproc(buf, etherread, port);
}
// assumes b is locked
static void
portunbind(Bridge *b, int argc, char *argv[])
{
int type = 0, i;
char name[KNAMELEN];
ulong ownhash;
Port *port = nil;
static char usage[] = "usage: unbind ether|tunnel addr [ownhash]";
memset(name, 0, KNAMELEN);
if(argc < 2 || argc > 3)
error(usage);
if(strcmp(argv[0], "ether") == 0) {
type = Tether;
strncpy(name, argv[1], KNAMELEN);
name[KNAMELEN-1] = 0;
// parseaddr(addr, argv[1], Eaddrlen);
} else if(strcmp(argv[0], "tunnel") == 0) {
type = Ttun;
strncpy(name, argv[1], KNAMELEN);
name[KNAMELEN-1] = 0;
// parseip(addr, argv[1]);
} else
error(usage);
if(argc == 3)
ownhash = atoi(argv[2]);
else
ownhash = 0;
for(i=0; i<b->nport; i++) {
port = b->port[i];
if(port != nil && port->type == type &&
memcmp(port->name, name, KNAMELEN) == 0)
break;
}
if(i == b->nport)
error("port not found");
if(ownhash != 0 && port->ownhash != 0 && ownhash != port->ownhash)
error("bad owner hash");
port->closed = 1;
b->port[i] = nil; // port is now unbound
cacheflushport(b, i);
// try and stop reader
if(port->readp)
postnote(port->readp, 1, "unbind", 0);
portfree(port);
}
// assumes b is locked
static Centry *
cachelookup(Bridge *b, uchar d[Eaddrlen])
{
int i;
uint h;
Centry *p;
long sec;
// dont cache multicast or broadcast
if(d[0] & 1)
return 0;
h = 0;
for(i=0; i<Eaddrlen; i++) {
h *= 7;
h += d[i];
}
h %= CacheHash;
p = b->cache + h;
sec = TK2SEC(m->ticks);
for(i=0; i<CacheLook; i++,p++) {
if(memcmp(d, p->d, Eaddrlen) == 0) {
p->dst++;
if(sec >= p->expire) {
log(b, Logcache, "expired cache entry: %E %d\n",
d, p->port);
return nil;
}
p->expire = sec + CacheTimeout;
return p;
}
}
log(b, Logcache, "cache miss: %E\n", d);
return nil;
}
// assumes b is locked
static void
cacheupdate(Bridge *b, uchar d[Eaddrlen], int port)
{
int i;
uint h;
Centry *p, *pp;
long sec;
// dont cache multicast or broadcast
if(d[0] & 1) {
log(b, Logcache, "bad source address: %E\n", d);
return;
}
h = 0;
for(i=0; i<Eaddrlen; i++) {
h *= 7;
h += d[i];
}
h %= CacheHash;
p = b->cache + h;
pp = p;
sec = p->expire;
// look for oldest entry
for(i=0; i<CacheLook; i++,p++) {
if(memcmp(p->d, d, Eaddrlen) == 0) {
p->expire = TK2SEC(m->ticks) + CacheTimeout;
if(p->port != port) {
log(b, Logcache, "NIC changed port %d->%d: %E\n",
p->port, port, d);
p->port = port;
}
p->src++;
return;
}
if(p->expire < sec) {
sec = p->expire;
pp = p;
}
}
if(pp->expire != 0)
log(b, Logcache, "bumping from cache: %E %d\n", pp->d, pp->port);
pp->expire = TK2SEC(m->ticks) + CacheTimeout;
memmove(pp->d, d, Eaddrlen);
pp->port = port;
pp->src = 1;
pp->dst = 0;
log(b, Logcache, "adding to cache: %E %d\n", pp->d, pp->port);
}
// assumes b is locked
static void
cacheflushport(Bridge *b, int port)
{
Centry *ce;
int i;
ce = b->cache;
for(i=0; i<CacheSize; i++,ce++) {
if(ce->port != port)
continue;
memset(ce, 0, sizeof(Centry));
}
}
static char *
cachedump(Bridge *b)
{
int i, n;
long sec, off;
char *buf, *p, *ep;
Centry *ce;
char c;
qlock(b);
if(waserror()) {
qunlock(b);
nexterror();
}
sec = TK2SEC(m->ticks);
n = 0;
for(i=0; i<CacheSize; i++)
if(b->cache[i].expire != 0)
n++;
n *= 51; // change if print format is changed
n += 10; // some slop at the end
buf = malloc(n);
if(buf == nil)
error(Enomem);
p = buf;
ep = buf + n;
ce = b->cache;
off = seconds() - sec;
for(i=0; i<CacheSize; i++,ce++) {
if(ce->expire == 0)
continue;
c = (sec < ce->expire)?'v':'e';
p += snprint(p, ep-p, "%E %2d %10ld %10ld %10ld %c\n", ce->d,
ce->port, ce->src, ce->dst, ce->expire+off, c);
}
*p = 0;
poperror();
qunlock(b);
return buf;
}
// assumes b is locked, no error return
static void
ethermultiwrite(Bridge *b, Block *bp, Port *port)
{
Port *oport;
Etherpkt *ep;
int i, mcast;
ep = (Etherpkt*)bp->rp;
mcast = ep->d[0] & 1; /* multicast bit of ethernet address */
oport = nil;
for(i=0; i<b->nport; i++) {
if(i == port->id || b->port[i] == nil)
continue;
/*
* we need to forward multicast packets for ipv6,
* so always do it.
*/
if(mcast)
b->port[i]->outmulti++;
else
b->port[i]->outunknown++;
// delay one so that the last write does not copy
if(oport != nil) {
b->copy++;
etherwrite(oport, copyblock(bp, BLEN(bp)));
}
oport = b->port[i];
}
// last write free block
if(oport)
etherwrite(oport, bp);
else
freeb(bp);
}
static void
tcpmsshack(Etherpkt *epkt, int n)
{
int hl, optlen;
Tcphdr *tcphdr;
ulong mss, cksum;
uchar *optr;
/* ignore non-ipv4 packets */
switch(nhgets(epkt->type)){
case ETIP4:
case ETIP6:
break;
default:
return;
}
n -= ETHERHDRSIZE;
if(n < 1)
return;
switch(epkt->data[0]&0xF0){
case IP_VER4:
hl = (epkt->data[0]&15)<<2;
if(n < hl+TCPHDR || hl < IP4HDR || epkt->data[9] != TCP)
return;
n -= hl;
tcphdr = (Tcphdr*)(epkt->data + hl);
break;
case IP_VER6:
if(n < IP6HDR+TCPHDR || epkt->data[6] != TCP)
return;
n -= IP6HDR;
tcphdr = (Tcphdr*)(epkt->data + IP6HDR);
break;
default:
return;
}
// MSS can only appear in SYN packet
if(!(tcphdr->flag[1] & SYN))
return;
hl = (tcphdr->flag[0] & 0xf0)>>2;
if(n < hl)
return;
// check for MSS option
optr = (uchar*)tcphdr + TCPHDR;
n = hl - TCPHDR;
for(;;) {
if(n <= 0 || *optr == EOLOPT)
return;
if(*optr == NOOPOPT) {
n--;
optr++;
continue;
}
optlen = optr[1];
if(optlen < 2 || optlen > n)
return;
if(*optr == MSSOPT && optlen == MSS_LENGTH)
break;
n -= optlen;
optr += optlen;
}
mss = nhgets(optr+2);
if(mss <= TcpMssMax)
return;
// fit checksum
cksum = nhgets(tcphdr->cksum);
if(optr-(uchar*)tcphdr & 1) {
// print("tcpmsshack: odd alignment!\n");
// odd alignments are a pain
cksum += nhgets(optr+1);
cksum -= (optr[1]<<8)|(TcpMssMax>>8);
cksum += (cksum>>16);
cksum &= 0xffff;
cksum += nhgets(optr+3);
cksum -= ((TcpMssMax&0xff)<<8)|optr[4];
cksum += (cksum>>16);
} else {
cksum += mss;
cksum -= TcpMssMax;
cksum += (cksum>>16);
}
hnputs(tcphdr->cksum, cksum);
hnputs(optr+2, TcpMssMax);
}
/*
* process to read from the ethernet
*/
static void
etherread(void *a)
{
Port *port = a;
Bridge *b = port->bridge;
Block *bp;
Etherpkt *ep;
Centry *ce;
long md, n;
qlock(b);
port->readp = up; /* hide identity under a rock for unbind */
while(!port->closed){
// release lock to read - error means it is time to quit
qunlock(b);
if(waserror()) {
print("etherread read error: %s\n", up->errstr);
qlock(b);
break;
}
bp = devtab[port->data[0]->type]->bread(port->data[0], MaxMTU, 0);
poperror();
qlock(b);
if(bp == nil)
break;
n = BLEN(bp);
if(port->closed || n < ETHERHDRSIZE){
freeb(bp);
continue;
}
if(waserror()) {
// print("etherread bridge error\n");
freeb(bp);
continue;
}
port->in++;
ep = (Etherpkt*)bp->rp;
cacheupdate(b, ep->s, port->id);
if(b->tcpmss)
tcpmsshack(ep, n);
/*
* delay packets to simulate a slow link
*/
if(b->delay0 != 0 || b->delayn != 0){
md = b->delay0 + b->delayn * n;
if(md > 0)
microdelay(md);
}
poperror(); /* must now dispose of bp */
if(ep->d[0] & 1) {
log(b, Logmcast, "multicast: port=%d src=%E dst=%E type=%#.4ux\n",
port->id, ep->s, ep->d, ep->type[0]<<8|ep->type[1]);
port->inmulti++;
ethermultiwrite(b, bp, port);
} else {
ce = cachelookup(b, ep->d);
if(ce == nil) {
b->miss++;
port->inunknown++;
ethermultiwrite(b, bp, port);
}else if(ce->port != port->id){
b->hit++;
etherwrite(b->port[ce->port], bp);
}else
freeb(bp);
}
}
// print("etherread: trying to exit\n");
port->readp = nil;
portfree(port);
qunlock(b);
pexit("hangup", 1);
}
static int
fragment(Etherpkt *epkt, int n)
{
Ip4hdr *iphdr;
if(n <= TunnelMtu)
return 0;
/* ignore non-ipv4 packets */
if(nhgets(epkt->type) != ETIP4)
return 0;
iphdr = (Ip4hdr*)(epkt->data);
n -= ETHERHDRSIZE;
/*
* ignore: IP runt packets, bad packets (I don't handle IP
* options for the moment), packets with don't-fragment set,
* and short blocks.
*/
if(n < IP4HDR || iphdr->vihl != (IP_VER4|IP_HLEN4) ||
iphdr->frag[0] & (IP_DF>>8) || nhgets(iphdr->length) > n)
return 0;
return 1;
}
static void
etherwrite(Port *port, Block *bp)
{
Ip4hdr *eh, *feh;
Etherpkt *epkt;
int n, lid, len, seglen, dlen, blklen, mf;
Block *nb;
ushort fragoff, frag;
port->out++;
n = BLEN(bp);
epkt = (Etherpkt*)bp->rp;
if(port->type != Ttun || !fragment(epkt, n)) {
if(!waserror()){
/* don't generate small packets */
if(n < ETHERMINTU)
bp = adjustblock(bp, ETHERMINTU);
devtab[port->data[1]->type]->bwrite(port->data[1], bp, 0);
poperror();
}
return;
}
port->outfrag++;
if(waserror()){
freeb(bp);
return;
}
seglen = (TunnelMtu - ETHERHDRSIZE - IP4HDR) & ~7;
eh = (Ip4hdr*)(epkt->data);
len = nhgets(eh->length);
frag = nhgets(eh->frag);
mf = frag & IP_MF;
frag <<= 3;
dlen = len - IP4HDR;
lid = nhgets(eh->id);
bp->rp += ETHERHDRSIZE+IP4HDR;
if(0)
print("seglen=%d, dlen=%d, mf=%x, frag=%d\n",
seglen, dlen, mf, frag);
for(fragoff = 0; fragoff < dlen; fragoff += seglen) {
nb = allocb(ETHERHDRSIZE+IP4HDR+seglen);
feh = (Ip4hdr*)(nb->wp+ETHERHDRSIZE);
memmove(nb->wp, epkt, ETHERHDRSIZE+IP4HDR);
nb->wp += ETHERHDRSIZE+IP4HDR;
if((fragoff + seglen) >= dlen) {
seglen = dlen - fragoff;
hnputs(feh->frag, (frag+fragoff)>>3 | mf);
}
else
hnputs(feh->frag, (frag+fragoff>>3) | IP_MF);
hnputs(feh->length, seglen + IP4HDR);
hnputs(feh->id, lid);
if(seglen){
blklen = BLEN(bp);
if(seglen < blklen)
blklen = seglen;
memmove(nb->wp, bp->rp, blklen);
nb->wp += blklen;
bp->rp += blklen;
}
feh->cksum[0] = 0;
feh->cksum[1] = 0;
hnputs(feh->cksum, ipcsum(&feh->vihl));
/* don't generate small packets */
if(BLEN(nb) < ETHERMINTU)
nb = adjustblock(nb, ETHERMINTU);
devtab[port->data[1]->type]->bwrite(port->data[1], nb, 0);
}
poperror();
freeb(bp);
}
// hold b lock
static void
portfree(Port *port)
{
if(decref(port) != 0)
return;
if(port->data[0])
cclose(port->data[0]);
if(port->data[1])
cclose(port->data[1]);
memset(port, 0, sizeof(Port));
free(port);
}
Dev bridgedevtab = {
'B',
"bridge",
devreset,
bridgeinit,
devshutdown,
bridgeattach,
bridgewalk,
bridgestat,
bridgeopen,
devcreate,
bridgeclose,
bridgeread,
devbread,
bridgewrite,
devbwrite,
devremove,
devwstat,
};