af_netrom.c

linux 内核源代码

static int nr_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct nr_sock *nr;

	if (sk == NULL) return 0;

	sock_hold(sk);
	lock_sock(sk);
	nr = nr_sk(sk);

	switch (nr->state) {
	case NR_STATE_0:
	case NR_STATE_1:
	case NR_STATE_2:
		nr_disconnect(sk, 0);
		nr_destroy_socket(sk);
		break;

	case NR_STATE_3:
		nr_clear_queues(sk);
		nr->n2count = 0;
		nr_write_internal(sk, NR_DISCREQ);
		nr_start_t1timer(sk);
		nr_stop_t2timer(sk);
		nr_stop_t4timer(sk);
		nr_stop_idletimer(sk);
		nr->state    = NR_STATE_2;
		sk->sk_state    = TCP_CLOSE;
		sk->sk_shutdown |= SEND_SHUTDOWN;
		sk->sk_state_change(sk);
		sock_orphan(sk);
		sock_set_flag(sk, SOCK_DESTROY);
		sk->sk_socket   = NULL;
		break;

	default:
		sk->sk_socket = NULL;
		break;
	}

	sock->sk   = NULL;
	release_sock(sk);
	sock_put(sk);

	return 0;
}

static int nr_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
	struct sock *sk = sock->sk;
	struct nr_sock *nr = nr_sk(sk);
	struct full_sockaddr_ax25 *addr = (struct full_sockaddr_ax25 *)uaddr;
	struct net_device *dev;
	ax25_uid_assoc *user;
	ax25_address *source;

	lock_sock(sk);
	if (!sock_flag(sk, SOCK_ZAPPED)) {
		release_sock(sk);
		return -EINVAL;
	}
	if (addr_len < sizeof(struct sockaddr_ax25) || addr_len > sizeof(struct full_sockaddr_ax25)) {
		release_sock(sk);
		return -EINVAL;
	}
	if (addr_len < (addr->fsa_ax25.sax25_ndigis * sizeof(ax25_address) + sizeof(struct sockaddr_ax25))) {
		release_sock(sk);
		return -EINVAL;
	}
	if (addr->fsa_ax25.sax25_family != AF_NETROM) {
		release_sock(sk);
		return -EINVAL;
	}
	if ((dev = nr_dev_get(&addr->fsa_ax25.sax25_call)) == NULL) {
		SOCK_DEBUG(sk, "NET/ROM: bind failed: invalid node callsign\n");
		release_sock(sk);
		return -EADDRNOTAVAIL;
	}

	/*
	 * Only the super user can set an arbitrary user callsign.
	 */
	if (addr->fsa_ax25.sax25_ndigis == 1) {
		if (!capable(CAP_NET_BIND_SERVICE)) {
			dev_put(dev);
			release_sock(sk);
			return -EACCES;
		}
		nr->user_addr   = addr->fsa_digipeater[0];
		nr->source_addr = addr->fsa_ax25.sax25_call;
	} else {
		source = &addr->fsa_ax25.sax25_call;

		user = ax25_findbyuid(current->euid);
		if (user) {
			nr->user_addr   = user->call;
			ax25_uid_put(user);
		} else {
			if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
				release_sock(sk);
				dev_put(dev);
				return -EPERM;
			}
			nr->user_addr   = *source;
		}

		nr->source_addr = *source;
	}

	nr->device = dev;
	nr_insert_socket(sk);

	sock_reset_flag(sk, SOCK_ZAPPED);
	dev_put(dev);
	release_sock(sk);
	SOCK_DEBUG(sk, "NET/ROM: socket is bound\n");
	return 0;
}

static int nr_connect(struct socket *sock, struct sockaddr *uaddr,
	int addr_len, int flags)
{
	struct sock *sk = sock->sk;
	struct nr_sock *nr = nr_sk(sk);
	struct sockaddr_ax25 *addr = (struct sockaddr_ax25 *)uaddr;
	ax25_address *source = NULL;
	ax25_uid_assoc *user;
	struct net_device *dev;
	int err = 0;

	lock_sock(sk);
	if (sk->sk_state == TCP_ESTABLISHED && sock->state == SS_CONNECTING) {
		sock->state = SS_CONNECTED;
		goto out_release;	/* Connect completed during a ERESTARTSYS event */
	}

	if (sk->sk_state == TCP_CLOSE && sock->state == SS_CONNECTING) {
		sock->state = SS_UNCONNECTED;
		err = -ECONNREFUSED;
		goto out_release;
	}

	if (sk->sk_state == TCP_ESTABLISHED) {
		err = -EISCONN;	/* No reconnect on a seqpacket socket */
		goto out_release;
	}

	sk->sk_state   = TCP_CLOSE;
	sock->state = SS_UNCONNECTED;

	if (addr_len != sizeof(struct sockaddr_ax25) && addr_len != sizeof(struct full_sockaddr_ax25)) {
		err = -EINVAL;
		goto out_release;
	}
	if (addr->sax25_family != AF_NETROM) {
		err = -EINVAL;
		goto out_release;
	}
	if (sock_flag(sk, SOCK_ZAPPED)) {	/* Must bind first - autobinding in this may or may not work */
		sock_reset_flag(sk, SOCK_ZAPPED);

		if ((dev = nr_dev_first()) == NULL) {
			err = -ENETUNREACH;
			goto out_release;
		}
		source = (ax25_address *)dev->dev_addr;

		user = ax25_findbyuid(current->euid);
		if (user) {
			nr->user_addr   = user->call;
			ax25_uid_put(user);
		} else {
			if (ax25_uid_policy && !capable(CAP_NET_ADMIN)) {
				dev_put(dev);
				err = -EPERM;
				goto out_release;
			}
			nr->user_addr   = *source;
		}

		nr->source_addr = *source;
		nr->device      = dev;

		dev_put(dev);
		nr_insert_socket(sk);		/* Finish the bind */
	}

	nr->dest_addr = addr->sax25_call;

	release_sock(sk);
	circuit = nr_find_next_circuit();
	lock_sock(sk);

	nr->my_index = circuit / 256;
	nr->my_id    = circuit % 256;

	circuit++;

	/* Move to connecting socket, start sending Connect Requests */
	sock->state  = SS_CONNECTING;
	sk->sk_state = TCP_SYN_SENT;

	nr_establish_data_link(sk);

	nr->state = NR_STATE_1;

	nr_start_heartbeat(sk);

	/* Now the loop */
	if (sk->sk_state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) {
		err = -EINPROGRESS;
		goto out_release;
	}

	/*
	 * A Connect Ack with Choke or timeout or failed routing will go to
	 * closed.
	 */
	if (sk->sk_state == TCP_SYN_SENT) {
		DEFINE_WAIT(wait);

		for (;;) {
			prepare_to_wait(sk->sk_sleep, &wait,
					TASK_INTERRUPTIBLE);
			if (sk->sk_state != TCP_SYN_SENT)
				break;
			if (!signal_pending(current)) {
				release_sock(sk);
				schedule();
				lock_sock(sk);
				continue;
			}
			err = -ERESTARTSYS;
			break;
		}
		finish_wait(sk->sk_sleep, &wait);
		if (err)
			goto out_release;
	}

	if (sk->sk_state != TCP_ESTABLISHED) {
		sock->state = SS_UNCONNECTED;
		err = sock_error(sk);	/* Always set at this point */
		goto out_release;
	}

	sock->state = SS_CONNECTED;

out_release:
	release_sock(sk);

	return err;
}

static int nr_accept(struct socket *sock, struct socket *newsock, int flags)
{
	struct sk_buff *skb;
	struct sock *newsk;
	DEFINE_WAIT(wait);
	struct sock *sk;
	int err = 0;

	if ((sk = sock->sk) == NULL)
		return -EINVAL;

	lock_sock(sk);
	if (sk->sk_type != SOCK_SEQPACKET) {
		err = -EOPNOTSUPP;
		goto out_release;
	}

	if (sk->sk_state != TCP_LISTEN) {
		err = -EINVAL;
		goto out_release;
	}

	/*
	 *	The write queue this time is holding sockets ready to use
	 *	hooked into the SABM we saved
	 */
	for (;;) {
		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
		skb = skb_dequeue(&sk->sk_receive_queue);
		if (skb)
			break;

		if (flags & O_NONBLOCK) {
			err = -EWOULDBLOCK;
			break;
		}
		if (!signal_pending(current)) {
			release_sock(sk);
			schedule();
			lock_sock(sk);
			continue;
		}
		err = -ERESTARTSYS;
		break;
	}
	finish_wait(sk->sk_sleep, &wait);
	if (err)
		goto out_release;

	newsk = skb->sk;
	newsk->sk_socket = newsock;
	newsk->sk_sleep = &newsock->wait;

	/* Now attach up the new socket */
	kfree_skb(skb);
	sk_acceptq_removed(sk);
	newsock->sk = newsk;

out_release:
	release_sock(sk);

	return err;
}

static int nr_getname(struct socket *sock, struct sockaddr *uaddr,
	int *uaddr_len, int peer)
{
	struct full_sockaddr_ax25 *sax = (struct full_sockaddr_ax25 *)uaddr;
	struct sock *sk = sock->sk;
	struct nr_sock *nr = nr_sk(sk);

	lock_sock(sk);
	if (peer != 0) {
		if (sk->sk_state != TCP_ESTABLISHED) {
			release_sock(sk);
			return -ENOTCONN;
		}
		sax->fsa_ax25.sax25_family = AF_NETROM;
		sax->fsa_ax25.sax25_ndigis = 1;
		sax->fsa_ax25.sax25_call   = nr->user_addr;
		sax->fsa_digipeater[0]     = nr->dest_addr;
		*uaddr_len = sizeof(struct full_sockaddr_ax25);
	} else {
		sax->fsa_ax25.sax25_family = AF_NETROM;
		sax->fsa_ax25.sax25_ndigis = 0;
		sax->fsa_ax25.sax25_call   = nr->source_addr;
		*uaddr_len = sizeof(struct sockaddr_ax25);
	}
	release_sock(sk);

	return 0;
}

int nr_rx_frame(struct sk_buff *skb, struct net_device *dev)
{
	struct sock *sk;
	struct sock *make;
	struct nr_sock *nr_make;
	ax25_address *src, *dest, *user;
	unsigned short circuit_index, circuit_id;
	unsigned short peer_circuit_index, peer_circuit_id;
	unsigned short frametype, flags, window, timeout;
	int ret;

	skb->sk = NULL;		/* Initially we don't know who it's for */

	/*
	 *	skb->data points to the netrom frame start
	 */

	src  = (ax25_address *)(skb->data + 0);
	dest = (ax25_address *)(skb->data + 7);

	circuit_index      = skb->data[15];
	circuit_id         = skb->data[16];
	peer_circuit_index = skb->data[17];
	peer_circuit_id    = skb->data[18];
	frametype          = skb->data[19] & 0x0F;
	flags              = skb->data[19] & 0xF0;

	/*
	 * Check for an incoming IP over NET/ROM frame.
	 */
	if (frametype == NR_PROTOEXT &&
	    circuit_index == NR_PROTO_IP && circuit_id == NR_PROTO_IP) {
		skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
		skb_reset_transport_header(skb);

		return nr_rx_ip(skb, dev);
	}

	/*
	 * Find an existing socket connection, based on circuit ID, if it's
	 * a Connect Request base it on their circuit ID.
	 *
	 * Circuit ID 0/0 is not valid but it could still be a "reset" for a
	 * circuit that no longer exists at the other end ...
	 */

	sk = NULL;

	if (circuit_index == 0 && circuit_id == 0) {
		if (frametype == NR_CONNACK && flags == NR_CHOKE_FLAG)
			sk = nr_find_peer(peer_circuit_index, peer_circuit_id, src);
	} else {
		if (frametype == NR_CONNREQ)
			sk = nr_find_peer(circuit_index, circuit_id, src);
		else
			sk = nr_find_socket(circuit_index, circuit_id);
	}

	if (sk != NULL) {
		skb_reset_transport_header(skb);

		if (frametype == NR_CONNACK && skb->len == 22)
			nr_sk(sk)->bpqext = 1;
		else
			nr_sk(sk)->bpqext = 0;

		ret = nr_process_rx_frame(sk, skb);
		bh_unlock_sock(sk);
		return ret;
	}

	/*
	 * Now it should be a CONNREQ.
	 */
	if (frametype != NR_CONNREQ) {
		/*
		 * Here it would be nice to be able to send a reset but
		 * NET/ROM doesn't have one.  We've tried to extend the protocol
		 * by sending NR_CONNACK | NR_CHOKE_FLAGS replies but that
		 * apparently kills BPQ boxes... :-(
		 * So now we try to follow the established behaviour of
		 * G8PZT's Xrouter which is sending packets with command type 7
		 * as an extension of the protocol.
		 */
		if (sysctl_netrom_reset_circuit &&
		    (frametype != NR_RESET || flags != 0))
			nr_transmit_reset(skb, 1);

		return 0;
	}

	sk = nr_find_listener(dest);

	user = (ax25_address *)(skb->data + 21);

	if (sk == NULL || sk_acceptq_is_full(sk) ||
	    (make = nr_make_new(sk)) == NULL) {
		nr_transmit_refusal(skb, 0);
		if (sk)
			bh_unlock_sock(sk);
		return 0;
	}

	window = skb->data[20];

	skb->sk             = make;
	make->sk_state	    = TCP_ESTABLISHED;

	/* Fill in his circuit details */
	nr_make = nr_sk(make);
	nr_make->source_addr = *dest;
	nr_make->dest_addr   = *src;
	nr_make->user_addr   = *user;

	nr_make->your_index  = circuit_index;
	nr_make->your_id     = circuit_id;

	bh_unlock_sock(sk);
	circuit = nr_find_next_circuit();
	bh_lock_sock(sk);

	nr_make->my_index    = circuit / 256;
	nr_make->my_id       = circuit % 256;

	circuit++;

	/* Window negotiation */
	if (window < nr_make->window)
		nr_make->window = window;

	/* L4 timeout negotiation */
	if (skb->len == 37) {
		timeout = skb->data[36] * 256 + skb->data[35];
		if (timeout * HZ < nr_make->t1)
			nr_make->t1 = timeout * HZ;
		nr_make->bpqext = 1;
	} else {
		nr_make->bpqext = 0;
	}

	nr_write_internal(make, NR_CONNACK);

	nr_make->condition = 0x00;
	nr_make->vs        = 0;
	nr_make->va        = 0;
	nr_make->vr        = 0;
	nr_make->vl        = 0;
	nr_make->state     = NR_STATE_3;
	sk_acceptq_added(sk);
	skb_queue_head(&sk->sk_receive_queue, skb);

	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk, skb->len);

	bh_unlock_sock(sk);

	nr_insert_socket(make);

	nr_start_heartbeat(make);