devinet.c

一个基于linux的TCP/IP协议栈的实现

	if( !in_dev ){
		if( event == NETDEV_REGISTER && dev == &loopback_dev ){
			in_dev = myinetdev_init( dev );
			if (!in_dev)
				panic("devinet: Failed to create loopback\n");
			in_dev->cnf.no_xfrm = 1;
			in_dev->cnf.no_policy = 1;
		}
		goto out;
	}

	switch (event) {
		case NETDEV_REGISTER:
			PR_DEBUG( "inetdev_event: bug\n");
			dev->ip_ptr = NULL;
			break;
		case NETDEV_UP:
			if(	dev->mtu < 68 )
				break;
			if(	dev == &loopback_dev ){
				struct in_ifaddr *ifa;
				if( (ifa = myinet_alloc_ifa()) != NULL ){
					ifa->ifa_local = ifa->ifa_address = htonl(INADDR_LOOPBACK);
					ifa->ifa_prefixlen = 8;
					ifa->ifa_mask = inet_make_mask(8);
					in_dev_hold(in_dev);
					ifa->ifa_dev = in_dev;
					ifa->ifa_scope = RT_SCOPE_HOST;
					memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
					myinet_insert_ifa(ifa);
				}
			}
			//ip_mc_up(in_dev);
			break;
		case NETDEV_DOWN:
			//ip_mc_down(in_dev);
			break;
		case NETDEV_CHANGEMTU:
			if (dev->mtu >= 68)
				break;
		case NETDEV_UNREGISTER:
			//myinetdev_destroy(in_dev);		//the kernel's code has done this!!!
			break;
		case NETDEV_CHANGENAME:
			myinetdev_changename(dev, in_dev);
/*
#ifdef CONFIG_SYSCTL
			devinet_sysctl_unregister(&in_dev->cnf);
			neigh_sysctl_unregister(in_dev->arp_parms);
			neigh_sysctl_register(dev, in_dev->arp_parms, NET_IPV4,
							NET_IPV4_NEIGH, "ipv4", NULL, NULL);
			devinet_sysctl_register(in_dev, &in_dev->cnf);
#endif
*/
			break;
	}		
out:
	return 0;
}

static __inline__ int myinet_abc_len(u32 addr)
{
	int rc = -1;

  	if( ZERONET(addr) )
  		rc = 0;
	else{
		addr = ntohl(addr);
		if (IN_CLASSA(addr))
			rc = 8;
		else if (IN_CLASSB(addr))
			rc = 16;
		else if (IN_CLASSC(addr))
			rc = 24;
	}
  	return rc;
}

static int myinet_set_ifa(struct net_device *dev, struct in_ifaddr *ifa)
{
	struct in_device *in_dev = __in_dev_get_rtnl(dev);
	ASSERT_RTNL();
	if (!in_dev) {
		in_dev = myinetdev_init(dev);
		if( !in_dev ){
			myinet_free_ifa(ifa);
			return -ENOBUFS;
		}
	}
	if( ifa->ifa_dev != in_dev ){
		BUG_TRAP( !ifa->ifa_dev );
		in_dev_hold(in_dev);
		ifa->ifa_dev = in_dev;
	}
	if( LOOPBACK(ifa->ifa_local) )
		ifa->ifa_scope = RT_SCOPE_HOST;
	return myinet_insert_ifa(ifa);
}

int mydevinet_ioctl(unsigned int cmd, void __user *arg)
{
	struct ifreq ifr;
	struct sockaddr_in sin_orig;
	struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
	char *colon;
	struct in_device *in_dev;
	struct in_ifaddr **ifap = NULL;
	struct in_ifaddr *ifa = NULL;
	struct net_device *dev;
	int ret = -EFAULT;
	int tryaddrmatch = 0;

	if( copy_from_user(&ifr, arg, sizeof(struct ifreq)) )
		goto out;
	ifr.ifr_name[IFNAMSIZ - 1] = 0;
	memcpy(&sin_orig, sin, sizeof(*sin));

	colon = strchr(ifr.ifr_name, ':');
	if( colon )
		*colon = 0;
#ifdef CONFIG_KMOD
	dev_load(ifr.ifr_name);
#endif

	switch(cmd) {
		case SIOCGIFADDR:
		case SIOCGIFBRDADDR:
		case SIOCGIFDSTADDR:
		case SIOCGIFNETMASK:
				tryaddrmatch = (sin_orig.sin_family == MY_AF_INET);
				memset( sin, 0, sizeof(*sin) );
				sin->sin_family = MY_AF_INET;
				break;
		case SIOCSIFFLAGS:
				ret = -EACCES;
				if( !capable(CAP_NET_ADMIN) )
					goto out;
				break;
		case SIOCSIFADDR:
		case SIOCSIFBRDADDR:
		case SIOCSIFDSTADDR:
		case SIOCSIFNETMASK:
				ret = -EACCES;
				if (!capable(CAP_NET_ADMIN))
						goto out;
				ret = -EINVAL;
				if (sin->sin_family != MY_AF_INET)
						goto out;
				break;
		default:
				ret = -EINVAL;
				goto out;
	}

	rtnl_lock();
	ret = -ENODEV;
	if( (dev = __dev_get_by_name(ifr.ifr_name)) == NULL )
		goto done;
	if( colon )
		*colon = ':';

	if( (in_dev = __in_dev_get_rtnl(dev)) != NULL ){
		if( tryaddrmatch ){
			for( ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL; ifap = &ifa->ifa_next ){
				if( !strcmp(ifr.ifr_name, ifa->ifa_label) &&
				    sin_orig.sin_addr.s_addr == ifa->ifa_address) {
					break;
				}
			}
		}
		if( !ifa ){
			for( ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL; ifap = &ifa->ifa_next )
				if( !strcmp(ifr.ifr_name, ifa->ifa_label) )
					break;
		}
	}

	ret = -EADDRNOTAVAIL;
	if( !ifa && cmd != SIOCSIFADDR && cmd != SIOCSIFFLAGS )
		goto done;

	switch(cmd) {
		case SIOCGIFADDR:
			sin->sin_addr.s_addr = ifa->ifa_local;
			goto rarok;
		case SIOCGIFBRDADDR:
			sin->sin_addr.s_addr = ifa->ifa_broadcast;
			goto rarok;
		case SIOCGIFDSTADDR:
			sin->sin_addr.s_addr = ifa->ifa_address;
			goto rarok;
		case SIOCGIFNETMASK:
			sin->sin_addr.s_addr = ifa->ifa_mask;
			goto rarok;
		case SIOCSIFBRDADDR:
			ret = 0;
			if( ifa->ifa_broadcast != sin->sin_addr.s_addr ){
				myinet_del_ifa(in_dev, ifap, 0);
				ifa->ifa_broadcast = sin->sin_addr.s_addr;
				myinet_insert_ifa(ifa);
			}
			break;
		case SIOCSIFADDR:
			ret = -EINVAL;
			if( myinet_abc_len(sin->sin_addr.s_addr) < 0)
				break;
			if( !ifa ){
				ret = -ENOBUFS;
				if( (ifa = myinet_alloc_ifa()) == NULL )
					break;
				if( colon )
					memcpy(ifa->ifa_label, ifr.ifr_name, IFNAMSIZ);
				else
					memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
			}else{
				ret = 0;
				if (ifa->ifa_local == sin->sin_addr.s_addr)
					break;
				myinet_del_ifa(in_dev, ifap, 0);
				ifa->ifa_broadcast = 0;
				ifa->ifa_anycast = 0;
			}
			ifa->ifa_address = ifa->ifa_local = sin->sin_addr.s_addr;
			if( !(dev->flags & IFF_POINTOPOINT) ){
				ifa->ifa_prefixlen = myinet_abc_len(ifa->ifa_address);
				ifa->ifa_mask = inet_make_mask(ifa->ifa_prefixlen);
				if( (dev->flags & IFF_BROADCAST) && ifa->ifa_prefixlen < 31 )
					ifa->ifa_broadcast = ifa->ifa_address | ~ifa->ifa_mask;
			}else{
				ifa->ifa_prefixlen = 32;
				ifa->ifa_mask = inet_make_mask(32);
			}
			ret = myinet_set_ifa(dev, ifa);
			break;
		case SIOCSIFFLAGS:
			if( colon ){
				ret = -EADDRNOTAVAIL;
				if( !ifa )
					break;
				ret = 0;
				if( !(ifr.ifr_flags & IFF_UP) )
					myinet_del_ifa( in_dev, ifap, 1 );
				break;
			}
			ret = mydev_change_flags( dev, ifr.ifr_flags );
			break;
		case SIOCSIFNETMASK:
			ret = -EINVAL;
			if( bad_mask(sin->sin_addr.s_addr, 0) )
				break;
			ret = 0;
			if (ifa->ifa_mask != sin->sin_addr.s_addr) {
				u32 old_mask = ifa->ifa_mask;
				myinet_del_ifa(in_dev, ifap, 0);
				ifa->ifa_mask = sin->sin_addr.s_addr;
				ifa->ifa_prefixlen = inet_mask_len(ifa->ifa_mask);
				if( (dev->flags & IFF_BROADCAST) && (ifa->ifa_prefixlen < 31) &&
								(ifa->ifa_broadcast == (ifa->ifa_local|~old_mask))) {
					ifa->ifa_broadcast = (ifa->ifa_local | ~sin->sin_addr.s_addr);
				}
				myinet_insert_ifa(ifa);
			}
			break;
		case SIOCSIFDSTADDR:
			ret = 0;
			if (ifa->ifa_address == sin->sin_addr.s_addr)
				break;
			ret = -EINVAL;
			if( myinet_abc_len(sin->sin_addr.s_addr) < 0 )
				break;
			ret = 0;
			myinet_del_ifa(in_dev, ifap, 0);
			ifa->ifa_address = sin->sin_addr.s_addr;
			myinet_insert_ifa(ifa);
			break;

	}
done:
	rtnl_unlock();
out:
	return ret;
rarok:
	rtnl_unlock();
	ret = copy_to_user(arg, &ifr, sizeof(struct ifreq)) ? -EFAULT : 0;
	goto out;
}

static struct notifier_block myip_netdev_notifier = {
	.notifier_call = myinetdev_event,
};

static int myinet_gifconf(struct net_device *dev, char __user *buf, int len)
{
	struct in_device *in_dev = __in_dev_get_rtnl(dev);
	struct in_ifaddr *ifa;
	struct ifreq ifr;
	int done = 0;

	if( !in_dev || (ifa = in_dev->ifa_list) == NULL )
		goto out;

	for (; ifa; ifa = ifa->ifa_next) {
		if( !buf ){
			done += sizeof(ifr);
			continue;
		}
		if( len < (int) sizeof(ifr) )
			break;
		memset(&ifr, 0, sizeof(struct ifreq));
		if( ifa->ifa_label )
			strcpy(ifr.ifr_name, ifa->ifa_label);
		else
			strcpy(ifr.ifr_name, dev->name);

		(*(struct sockaddr_in *)&ifr.ifr_addr).sin_family = MY_AF_INET;
		(*(struct sockaddr_in *)&ifr.ifr_addr).sin_addr.s_addr = ifa->ifa_local;

		if (copy_to_user(buf, &ifr, sizeof(struct ifreq))) {
			done = -EFAULT;
			break;
		}
		buf  += sizeof(struct ifreq);
		len  -= sizeof(struct ifreq);
		done += sizeof(struct ifreq);
	}
out:
	return done;
}

void __init mydevinet_init(void)
{
	myregister_gifconf( MY_PF_INET, myinet_gifconf );
	myregister_netdevice_notifier( &myip_netdev_notifier );

}

void __exit mydevinet_exit(void)
{
	myunregister_netdevice_notifier( &myip_netdev_notifier );
	myunregister_gifconf( MY_PF_INET );
}

EXPORT_SYMBOL_GPL( mydevinet_ioctl );