ipifc.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

	x = nil; memset(xmask, 0, IPaddrlen);

	/* find most specific match */
	e = &f->ipifc->conv[f->ipifc->nc];
	for(cp = f->ipifc->conv; cp < e; cp++){
		if(*cp == 0)
			continue;

		ifc = (Ipifc*)(*cp)->ptcl;

		for(lifc = ifc->lifc; lifc; lifc = lifc->next){
			maskip(remote, lifc->mask, gnet);
			if(ipcmp(gnet, lifc->net) == 0){
				if(x == nil || ipcmp(lifc->mask, xmask) > 0){
					x = ifc;
					ipmove(xmask, lifc->mask);
				}
			}
		}
	}
	if(x != nil)
		return x;

	/* for now for broadcast and multicast, just use first interface */
	if(type & (Rbcast|Rmulti)){
		for(cp = f->ipifc->conv; cp < e; cp++){
			if(*cp == 0)
				continue;
			ifc = (Ipifc*)(*cp)->ptcl;
			if(ifc->lifc != nil)
				return ifc;
		}
	}

	return nil;
}

enum {
	unknownv6,
	multicastv6,
	unspecifiedv6,
	linklocalv6,
	sitelocalv6,
	globalv6,
};

int
v6addrtype(uchar *addr)
{
	if(isv6global(addr))
		return globalv6;
	if(islinklocal(addr))
		return linklocalv6;
	if(isv6mcast(addr))
		return multicastv6;
	if(issitelocal(addr))
		return sitelocalv6;
	return unknownv6;
}

#define v6addrcurr(lifc) (( (lifc)->origint + (lifc)->preflt >= (NOW/10^3) ) || ( (lifc)->preflt == 0xffffffff ))

static void
findprimaryipv6(Fs *f, uchar *local)
{
	Conv **cp, **e;
	Ipifc *ifc;
	Iplifc *lifc;
	int atype, atypel;

	ipmove(local, v6Unspecified);
	atype = unspecifiedv6;

	/* find "best" (global > sitelocal > link local > unspecified)
	 * local address; address must be current */

	e = &f->ipifc->conv[f->ipifc->nc];
	for(cp = f->ipifc->conv; cp < e; cp++){
		if(*cp == 0)
			continue;
		ifc = (Ipifc*)(*cp)->ptcl;
		for(lifc = ifc->lifc; lifc; lifc = lifc->next){
			atypel = v6addrtype(lifc->local);
			if(atypel > atype)
			if(v6addrcurr(lifc)) {
				ipmove(local, lifc->local);
				atype = atypel;
				if(atype == globalv6)
					return;
			}
		}
	}
}

/*
 *  returns first ip address configured
 */
static void
findprimaryipv4(Fs *f, uchar *local)
{
	Conv **cp, **e;
	Ipifc *ifc;
	Iplifc *lifc;

	/* find first ifc local address */
	e = &f->ipifc->conv[f->ipifc->nc];
	for(cp = f->ipifc->conv; cp < e; cp++){
		if(*cp == 0)
			continue;
		ifc = (Ipifc*)(*cp)->ptcl;
		if((lifc = ifc->lifc) != nil){
			ipmove(local, lifc->local);
			return;
		}
	}
}

/*
 *  find the local address 'closest' to the remote system, copy it to
 *  local and return the ifc for that address
 */
void
findlocalip(Fs *f, uchar *local, uchar *remote)
{
	Ipifc *ifc;
	Iplifc *lifc;
	Route *r;
	uchar gate[IPaddrlen];
	uchar gnet[IPaddrlen];
	int version;
	int atype = unspecifiedv6, atypel = unknownv6;

	USED(atype);
	USED(atypel);
	qlock(f->ipifc);
	r = v6lookup(f, remote, nil);
 	version = (memcmp(remote, v4prefix, IPv4off) == 0) ? V4 : V6;

	if(r != nil){
		ifc = r->ifc;
		if(r->type & Rv4)
			v4tov6(gate, r->v4.gate);
		else {
			ipmove(gate, r->v6.gate);
			ipmove(local, v6Unspecified);
		}

		/* find ifc address closest to the gateway to use */
		switch(version) {
		case V4:
			for(lifc = ifc->lifc; lifc; lifc = lifc->next){
				maskip(gate, lifc->mask, gnet);
				if(ipcmp(gnet, lifc->net) == 0){
					ipmove(local, lifc->local);
					goto out;
				}
			}
			break;
		case V6:
			for(lifc = ifc->lifc; lifc; lifc = lifc->next){
				atypel = v6addrtype(lifc->local);
				maskip(gate, lifc->mask, gnet);
				if(ipcmp(gnet, lifc->net) == 0)
				if(atypel > atype)
				if(v6addrcurr(lifc)) {
					ipmove(local, lifc->local);
					atype = atypel;
					if(atype == globalv6)
						break;
				}
			}
			if(atype > unspecifiedv6)
				goto out;
			break;
		default:
			panic("findlocalip: version %d", version);
		}
	}

	switch(version){
	case V4:
		findprimaryipv4(f, local);
		break;
	case V6:
		findprimaryipv6(f, local);
		break;
	default:
		panic("findlocalip2: version %d", version);
	}

out:
	qunlock(f->ipifc);
}

/*
 *  return first v4 address associated with an interface
 */
int
ipv4local(Ipifc *ifc, uchar *addr)
{
	Iplifc *lifc;

	for(lifc = ifc->lifc; lifc; lifc = lifc->next){
		if(isv4(lifc->local)){
			memmove(addr, lifc->local+IPv4off, IPv4addrlen);
			return 1;
		}
	}
	return 0;
}

/*
 *  return first v6 address associated with an interface
 */
int
ipv6local(Ipifc *ifc, uchar *addr)
{
	Iplifc *lifc;

	for(lifc = ifc->lifc; lifc; lifc = lifc->next){
		if(!isv4(lifc->local) && !(lifc->tentative)){
			ipmove(addr, lifc->local);
			return 1;
		}
	}
	return 0;
}

int
ipv6anylocal(Ipifc *ifc, uchar *addr)
{
	Iplifc *lifc;

	for(lifc = ifc->lifc; lifc; lifc = lifc->next){
		if(!isv4(lifc->local)){
			ipmove(addr, lifc->local);
			return SRC_UNI;
		}
	}
	return SRC_UNSPEC;
}

/*
 *  see if this address is bound to the interface
 */
Iplifc*
iplocalonifc(Ipifc *ifc, uchar *ip)
{
	Iplifc *lifc;

	for(lifc = ifc->lifc; lifc; lifc = lifc->next)
		if(ipcmp(ip, lifc->local) == 0)
			return lifc;
	return nil;
}


/*
 *  See if we're proxying for this address on this interface
 */
int
ipproxyifc(Fs *f, Ipifc *ifc, uchar *ip)
{
	Route *r;
	uchar net[IPaddrlen];
	Iplifc *lifc;

	/* see if this is a direct connected pt to pt address */
	r = v6lookup(f, ip, nil);
	if(r == nil)
		return 0;
	if((r->type & (Rifc|Rproxy)) != (Rifc|Rproxy))
		return 0;

	/* see if this is on the right interface */
	for(lifc = ifc->lifc; lifc; lifc = lifc->next){
		maskip(ip, lifc->mask, net);
		if(ipcmp(net, lifc->remote) == 0)
			return 1;
	}

	return 0;
}

/*
 *  return multicast version if any
 */
int
ipismulticast(uchar *ip)
{
	if(isv4(ip)){
		if(ip[IPv4off] >= 0xe0 && ip[IPv4off] < 0xf0)
			return V4;
	} else {
		if(ip[0] == 0xff)
			return V6;
	}
	return 0;
}
int
ipisbm(uchar *ip)
{
	if(isv4(ip)){
		if(ip[IPv4off] >= 0xe0 && ip[IPv4off] < 0xf0)
			return V4;
		if(ipcmp(ip, IPv4bcast) == 0)
			return V4;
	} else {
		if(ip[0] == 0xff)
			return V6;
	}
	return 0;
}


/*
 *  add a multicast address to an interface, called with c->car locked
 */
void
ipifcaddmulti(Conv *c, uchar *ma, uchar *ia)
{
	Ipifc *ifc;
	Iplifc *lifc;
	Conv **p;
	Ipmulti *multi, **l;
	Fs *f;

	f = c->p->f;

	for(l = &c->multi; *l; l = &(*l)->next)
		if(ipcmp(ma, (*l)->ma) == 0)
		if(ipcmp(ia, (*l)->ia) == 0)
			return;		/* it's already there */

	multi = *l = smalloc(sizeof(*multi));
	ipmove(multi->ma, ma);
	ipmove(multi->ia, ia);
	multi->next = nil;

	for(p = f->ipifc->conv; *p; p++){
		if((*p)->inuse == 0)
			continue;
		ifc = (Ipifc*)(*p)->ptcl;
		if(waserror()){
			wunlock(ifc);
			nexterror();
		}
		wlock(ifc);
		for(lifc = ifc->lifc; lifc; lifc = lifc->next)
			if(ipcmp(ia, lifc->local) == 0)
				addselfcache(f, ifc, lifc, ma, Rmulti);
		wunlock(ifc);
		poperror();
	}
}


/*
 *  remove a multicast address from an interface, called with c->car locked
 */
void
ipifcremmulti(Conv *c, uchar *ma, uchar *ia)
{
	Ipmulti *multi, **l;
	Iplifc *lifc;
	Conv **p;
	Ipifc *ifc;
	Fs *f;

	f = c->p->f;

	for(l = &c->multi; *l; l = &(*l)->next)
		if(ipcmp(ma, (*l)->ma) == 0)
		if(ipcmp(ia, (*l)->ia) == 0)
			break;

	multi = *l;
	if(multi == nil)
		return; 	/* we don't have it open */

	*l = multi->next;

	for(p = f->ipifc->conv; *p; p++){
		if((*p)->inuse == 0)
			continue;

		ifc = (Ipifc*)(*p)->ptcl;
		if(waserror()){
			wunlock(ifc);
			nexterror();
		}
		wlock(ifc);
		for(lifc = ifc->lifc; lifc; lifc = lifc->next)
			if(ipcmp(ia, lifc->local) == 0)
				remselfcache(f, ifc, lifc, ma);
		wunlock(ifc);
		poperror();
	}

	free(multi);
}

/*
 *  make lifc's join and leave multicast groups
 */
static char*
ipifcjoinmulti(Ipifc *ifc, char **argv, int argc)
{
	USED(ifc, argv, argc);
	return nil;
}

static char*
ipifcleavemulti(Ipifc *ifc, char **argv, int argc)
{
	USED(ifc, argv, argc);
	return nil;
}

static void
ipifcregisterproxy(Fs *f, Ipifc *ifc, uchar *ip)
{
	Conv **cp, **e;
	Ipifc *nifc;
	Iplifc *lifc;
	Medium *m;
	uchar net[IPaddrlen];

	/* register the address on any network that will proxy for us */
	e = &f->ipifc->conv[f->ipifc->nc];

	if(!isv4(ip)) { // V6
		for(cp = f->ipifc->conv; cp < e; cp++){
			if(*cp == nil)
				continue;
			nifc = (Ipifc*)(*cp)->ptcl;
			if(nifc == ifc)
				continue;

			rlock(nifc);
			m = nifc->m;
			if(m == nil || m->addmulti == nil) {
				runlock(nifc);
				continue;
			}
			for(lifc = nifc->lifc; lifc; lifc = lifc->next){
				maskip(ip, lifc->mask, net);
				if(ipcmp(net, lifc->remote) == 0) { /* add solicited-node multicast address */
					ipv62smcast(net, ip);
					addselfcache(f, nifc, lifc, net, Rmulti);
					arpenter(f, V6, ip, nifc->mac, 6, 0);
					//(*m->addmulti)(nifc, net, ip);
					break;
				}
			}
			runlock(nifc);
		}
		return;
	}
	else { // V4
		for(cp = f->ipifc->conv; cp < e; cp++){
			if(*cp == nil)
				continue;
			nifc = (Ipifc*)(*cp)->ptcl;
			if(nifc == ifc)
				continue;

			rlock(nifc);
			m = nifc->m;
			if(m == nil || m->areg == nil){
				runlock(nifc);
				continue;
			}
			for(lifc = nifc->lifc; lifc; lifc = lifc->next){
				maskip(ip, lifc->mask, net);
				if(ipcmp(net, lifc->remote) == 0){
					(*m->areg)(nifc, ip);
					break;
				}
			}
			runlock(nifc);
		}
	}
}


// added for new v6 mesg types
static void
adddefroute6(Fs *f, uchar *gate, int force)
{
	Route *r;

	r = v6lookup(f, v6Unspecified, nil);
	if(r!=nil)
	if(!(force) && (strcmp(r->tag,"ra")!=0))	// route entries generated
		return;			// by all other means take
					// precedence over router annc

	v6delroute(f, v6Unspecified, v6Unspecified, 1);
	v6addroute(f, "ra", v6Unspecified, v6Unspecified, gate, 0);
}

enum
{
	Ngates = 3,
};

char*
ipifcaddpref6(Ipifc *ifc, char**argv, int argc)
{
	uchar	onlink = 1;
	uchar	autoflag = 1;
	long 	validlt = 0xffffffff;
	long 	preflt = 0xffffffff;
	long	origint = NOW / 10^3;
	uchar	prefix[IPaddrlen];
	int	plen = 64;
	Iplifc	*lifc;
	char	addr[40], preflen[6];
	char	*params[3];

	switch(argc) {
	case 7:
		preflt = atoi(argv[6]);
		/* fall through */
	case 6:
		validlt = atoi(argv[5]);
		/* fall through */
	case 5:
		autoflag = atoi(argv[4]);
		/* fall through */
	case 4:
		onlink = atoi(argv[3]);
		/* fall through */
	case 3:
		plen = atoi(argv[2]);
	case 2:
		break;
	default:
		return Ebadarg;
	}

	if((parseip(prefix, argv[1])!=6) ||
	 	(validlt < preflt) ||
		(plen < 0) || (plen > 64) ||
		(islinklocal(prefix))
	)
		return Ebadarg;

	lifc = smalloc(sizeof(Iplifc));
	lifc->onlink = (onlink!=0);
	lifc->autoflag = (autoflag!=0);
	lifc->validlt = validlt;
	lifc->preflt = preflt;
	lifc->origint = origint;

	if(ifc->m->pref2addr!=nil)
		ifc->m->pref2addr(prefix, ifc->mac);
	else
		return Ebadarg;

	sprint(addr, "%I", prefix);
	sprint(preflen, "/%d", plen);
	params[0] = "add";
	params[1] = addr;
	params[2] = preflen;

	return ipifcadd(ifc, params, 3, 0, lifc);
}