Bluetooth: Add initial support for ERTM packets transfers

This patch adds support for ERTM transfers, without retransmission, with
txWindow up to 63 and with acknowledgement of packets received. Now the
packets are queued before call l2cap_do_send(), so packets couldn't be
sent at the time we call l2cap_sock_sendmsg(). They will be sent in
an asynchronous way on later calls of l2cap_ertm_send(). Besides if an
error occurs on calling l2cap_do_send() we disconnect the channel.

Initially based on a patch from Nathan Holstein <nathan@lampreynetworks.com>

Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 335 insertions, 49 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index c1b5620..45b8697 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -333,6 +333,30 @@ static inline int l2cap_send_cmd(struct l2cap_conn *conn, u8 ident, u8 code, u16
 	return hci_send_acl(conn->hcon, skb, 0);
 }
 
+static inline int l2cap_send_sframe(struct l2cap_pinfo *pi, u16 control)
+{
+	struct sk_buff *skb;
+	struct l2cap_hdr *lh;
+	struct l2cap_conn *conn = pi->conn;
+	int count;
+
+	BT_DBG("pi %p, control 0x%2.2x", pi, control);
+
+	count = min_t(unsigned int, conn->mtu, L2CAP_HDR_SIZE + 2);
+	control |= L2CAP_CTRL_FRAME_TYPE;
+
+	skb = bt_skb_alloc(count, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
+	lh->len = cpu_to_le16(2);
+	lh->cid = cpu_to_le16(pi->dcid);
+	put_unaligned_le16(control, skb_put(skb, 2));
+
+	return hci_send_acl(pi->conn->hcon, skb, 0);
+}
+
 static void l2cap_do_start(struct sock *sk)
 {
 	struct l2cap_conn *conn = l2cap_pi(sk)->conn;
@@ -1154,39 +1178,80 @@ static int l2cap_sock_getname(struct socket *sock, struct sockaddr *addr, int *l
 	return 0;
 }
 
-static inline int l2cap_do_send(struct sock *sk, struct msghdr *msg, int len)
+static void l2cap_drop_acked_frames(struct sock *sk)
 {
-	struct l2cap_conn *conn = l2cap_pi(sk)->conn;
-	struct sk_buff *skb, **frag;
-	int err, hlen, count, sent = 0;
-	struct l2cap_hdr *lh;
+	struct sk_buff *skb;
 
-	BT_DBG("sk %p len %d", sk, len);
+	while ((skb = skb_peek(TX_QUEUE(sk)))) {
+		if (bt_cb(skb)->tx_seq == l2cap_pi(sk)->expected_ack_seq)
+			break;
 
-	/* First fragment (with L2CAP header) */
-	if (sk->sk_type == SOCK_DGRAM)
-		hlen = L2CAP_HDR_SIZE + 2;
-	else
-		hlen = L2CAP_HDR_SIZE;
+		skb = skb_dequeue(TX_QUEUE(sk));
+		kfree_skb(skb);
 
-	count = min_t(unsigned int, (conn->mtu - hlen), len);
+		l2cap_pi(sk)->unacked_frames--;
+	}
 
-	skb = bt_skb_send_alloc(sk, hlen + count,
-			msg->msg_flags & MSG_DONTWAIT, &err);
-	if (!skb)
-		return err;
+	return;
+}
 
-	/* Create L2CAP header */
-	lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
-	lh->cid = cpu_to_le16(l2cap_pi(sk)->dcid);
-	lh->len = cpu_to_le16(len + (hlen - L2CAP_HDR_SIZE));
+static inline int l2cap_do_send(struct sock *sk, struct sk_buff *skb)
+{
+	struct l2cap_pinfo *pi = l2cap_pi(sk);
+	int err;
+
+	BT_DBG("sk %p, skb %p len %d", sk, skb, skb->len);
+
+	err = hci_send_acl(pi->conn->hcon, skb, 0);
+	if (err < 0)
+		kfree_skb(skb);
+
+	return err;
+}
+
+static int l2cap_ertm_send(struct sock *sk)
+{
+	struct sk_buff *skb, *tx_skb;
+	struct l2cap_pinfo *pi = l2cap_pi(sk);
+	u16 control;
+	int err;
+
+	while ((skb = sk->sk_send_head) && (!l2cap_tx_window_full(sk))) {
+		tx_skb = skb_clone(skb, GFP_ATOMIC);
 
-	if (sk->sk_type == SOCK_DGRAM)
-		put_unaligned(l2cap_pi(sk)->psm, (__le16 *) skb_put(skb, 2));
+		control = get_unaligned_le16(tx_skb->data + L2CAP_HDR_SIZE);
+		control |= (pi->req_seq << L2CAP_CTRL_REQSEQ_SHIFT)
+				| (pi->next_tx_seq << L2CAP_CTRL_TXSEQ_SHIFT);
+		put_unaligned_le16(control, tx_skb->data + L2CAP_HDR_SIZE);
+
+		err = l2cap_do_send(sk, tx_skb);
+		if (err < 0) {
+			l2cap_send_disconn_req(pi->conn, sk);
+			return err;
+		}
+
+		bt_cb(skb)->tx_seq = pi->next_tx_seq;
+		pi->next_tx_seq = (pi->next_tx_seq + 1) % 64;
+
+		pi->unacked_frames++;
+
+		if (skb_queue_is_last(TX_QUEUE(sk), skb))
+			sk->sk_send_head = NULL;
+		else
+			sk->sk_send_head = skb_queue_next(TX_QUEUE(sk), skb);
+	}
+
+	return 0;
+}
+
+static inline int l2cap_skbuff_fromiovec(struct sock *sk, struct msghdr *msg, int len, int count, struct sk_buff *skb)
+{
+	struct l2cap_conn *conn = l2cap_pi(sk)->conn;
+	struct sk_buff **frag;
+	int err, sent = 0;
 
 	if (memcpy_fromiovec(skb_put(skb, count), msg->msg_iov, count)) {
-		err = -EFAULT;
-		goto fail;
+		return -EFAULT;
 	}
 
 	sent += count;
@@ -1199,33 +1264,112 @@ static inline int l2cap_do_send(struct sock *sk, struct msghdr *msg, int len)
 
 		*frag = bt_skb_send_alloc(sk, count, msg->msg_flags & MSG_DONTWAIT, &err);
 		if (!*frag)
-			goto fail;
-
-		if (memcpy_fromiovec(skb_put(*frag, count), msg->msg_iov, count)) {
-			err = -EFAULT;
-			goto fail;
-		}
+			return -EFAULT;
+		if (memcpy_fromiovec(skb_put(*frag, count), msg->msg_iov, count))
+			return -EFAULT;
 
 		sent += count;
 		len  -= count;
 
 		frag = &(*frag)->next;
 	}
-	err = hci_send_acl(conn->hcon, skb, 0);
-	if (err < 0)
-		goto fail;
 
 	return sent;
+}
 
-fail:
-	kfree_skb(skb);
-	return err;
+static struct sk_buff *l2cap_create_connless_pdu(struct sock *sk, struct msghdr *msg, size_t len)
+{
+	struct l2cap_conn *conn = l2cap_pi(sk)->conn;
+	struct sk_buff *skb;
+	int err, count, hlen = L2CAP_HDR_SIZE + 2;
+	struct l2cap_hdr *lh;
+
+	BT_DBG("sk %p len %d", sk, (int)len);
+
+	count = min_t(unsigned int, (conn->mtu - hlen), len);
+	skb = bt_skb_send_alloc(sk, count + hlen,
+			msg->msg_flags & MSG_DONTWAIT, &err);
+	if (!skb)
+		return ERR_PTR(-ENOMEM);
+
+	/* Create L2CAP header */
+	lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
+	lh->cid = cpu_to_le16(l2cap_pi(sk)->dcid);
+	lh->len = cpu_to_le16(len + (hlen - L2CAP_HDR_SIZE));
+	put_unaligned_le16(l2cap_pi(sk)->psm, skb_put(skb, 2));
+
+	err = l2cap_skbuff_fromiovec(sk, msg, len, count, skb);
+	if (unlikely(err < 0)) {
+		kfree_skb(skb);
+		return ERR_PTR(err);
+	}
+	return skb;
+}
+
+static struct sk_buff *l2cap_create_basic_pdu(struct sock *sk, struct msghdr *msg, size_t len)
+{
+	struct l2cap_conn *conn = l2cap_pi(sk)->conn;
+	struct sk_buff *skb;
+	int err, count, hlen = L2CAP_HDR_SIZE;
+	struct l2cap_hdr *lh;
+
+	BT_DBG("sk %p len %d", sk, (int)len);
+
+	count = min_t(unsigned int, (conn->mtu - hlen), len);
+	skb = bt_skb_send_alloc(sk, count + hlen,
+			msg->msg_flags & MSG_DONTWAIT, &err);
+	if (!skb)
+		return ERR_PTR(-ENOMEM);
+
+	/* Create L2CAP header */
+	lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
+	lh->cid = cpu_to_le16(l2cap_pi(sk)->dcid);
+	lh->len = cpu_to_le16(len + (hlen - L2CAP_HDR_SIZE));
+
+	err = l2cap_skbuff_fromiovec(sk, msg, len, count, skb);
+	if (unlikely(err < 0)) {
+		kfree_skb(skb);
+		return ERR_PTR(err);
+	}
+	return skb;
+}
+
+static struct sk_buff *l2cap_create_ertm_pdu(struct sock *sk, struct msghdr *msg, size_t len, u16 control)
+{
+	struct l2cap_conn *conn = l2cap_pi(sk)->conn;
+	struct sk_buff *skb;
+	int err, count, hlen = L2CAP_HDR_SIZE + 2;
+	struct l2cap_hdr *lh;
+
+	BT_DBG("sk %p len %d", sk, (int)len);
+
+	count = min_t(unsigned int, (conn->mtu - hlen), len);
+	skb = bt_skb_send_alloc(sk, count + hlen,
+			msg->msg_flags & MSG_DONTWAIT, &err);
+	if (!skb)
+		return ERR_PTR(-ENOMEM);
+
+	/* Create L2CAP header */
+	lh = (struct l2cap_hdr *) skb_put(skb, L2CAP_HDR_SIZE);
+	lh->cid = cpu_to_le16(l2cap_pi(sk)->dcid);
+	lh->len = cpu_to_le16(len + (hlen - L2CAP_HDR_SIZE));
+	put_unaligned_le16(control, skb_put(skb, 2));
+
+	err = l2cap_skbuff_fromiovec(sk, msg, len, count, skb);
+	if (unlikely(err < 0)) {
+		kfree_skb(skb);
+		return ERR_PTR(err);
+	}
+	return skb;
 }
 
 static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg, size_t len)
 {
 	struct sock *sk = sock->sk;
-	int err = 0;
+	struct l2cap_pinfo *pi = l2cap_pi(sk);
+	struct sk_buff *skb;
+	u16 control;
+	int err;
 
 	BT_DBG("sock %p, sk %p", sock, sk);
 
@@ -1237,16 +1381,67 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
 		return -EOPNOTSUPP;
 
 	/* Check outgoing MTU */
-	if (sk->sk_type != SOCK_RAW && len > l2cap_pi(sk)->omtu)
+	if (sk->sk_type == SOCK_SEQPACKET && pi->mode == L2CAP_MODE_BASIC
+			&& len > pi->omtu)
 		return -EINVAL;
 
 	lock_sock(sk);
 
-	if (sk->sk_state == BT_CONNECTED)
-		err = l2cap_do_send(sk, msg, len);
-	else
+	if (sk->sk_state != BT_CONNECTED) {
 		err = -ENOTCONN;
+		goto done;
+	}
+
+	/* Connectionless channel */
+	if (sk->sk_type == SOCK_DGRAM) {
+		skb = l2cap_create_connless_pdu(sk, msg, len);
+		err = l2cap_do_send(sk, skb);
+		goto done;
+	}
 
+	switch (pi->mode) {
+	case L2CAP_MODE_BASIC:
+		/* Create a basic PDU */
+		skb = l2cap_create_basic_pdu(sk, msg, len);
+		if (IS_ERR(skb)) {
+			err = PTR_ERR(skb);
+			goto done;
+		}
+
+		err = l2cap_do_send(sk, skb);
+		if (!err)
+			err = len;
+		break;
+
+	case L2CAP_MODE_ERTM:
+		/* Entire SDU fits into one PDU */
+		if (len <= pi->omtu) {
+			control = L2CAP_SDU_UNSEGMENTED;
+			skb = l2cap_create_ertm_pdu(sk, msg, len, control);
+			if (IS_ERR(skb)) {
+				err = PTR_ERR(skb);
+				goto done;
+			}
+		} else {
+			/* FIXME: Segmentation will be added later */
+			err = -EINVAL;
+			goto done;
+		}
+		__skb_queue_tail(TX_QUEUE(sk), skb);
+		if (sk->sk_send_head == NULL)
+			sk->sk_send_head = skb;
+
+		err = l2cap_ertm_send(sk);
+		if (!err)
+			err = len;
+		break;
+
+	default:
+		BT_DBG("bad state %1.1x", pi->mode);
+		err = -EINVAL;
+	}
+
+done:
 	release_sock(sk);
 	return err;
 }
@@ -2301,6 +2496,10 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
 
 	if (l2cap_pi(sk)->conf_state & L2CAP_CONF_INPUT_DONE) {
 		sk->sk_state = BT_CONNECTED;
+		l2cap_pi(sk)->next_tx_seq = 0;
+		l2cap_pi(sk)->expected_ack_seq = 0;
+		l2cap_pi(sk)->unacked_frames = 0;
+		__skb_queue_head_init(TX_QUEUE(sk));
 		l2cap_chan_ready(sk);
 		goto unlock;
 	}
@@ -2375,6 +2574,9 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
 
 	if (l2cap_pi(sk)->conf_state & L2CAP_CONF_OUTPUT_DONE) {
 		sk->sk_state = BT_CONNECTED;
+		l2cap_pi(sk)->expected_tx_seq = 0;
+		l2cap_pi(sk)->num_to_ack = 0;
+		__skb_queue_head_init(TX_QUEUE(sk));
 		l2cap_chan_ready(sk);
 	}
 
@@ -2405,6 +2607,8 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd
 
 	sk->sk_shutdown = SHUTDOWN_MASK;
 
+	skb_queue_purge(TX_QUEUE(sk));
+
 	l2cap_chan_del(sk, ECONNRESET);
 	bh_unlock_sock(sk);
 
@@ -2427,6 +2631,8 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn, struct l2cap_cmd
 	if (!sk)
 		return 0;
 
+	skb_queue_purge(TX_QUEUE(sk));
+
 	l2cap_chan_del(sk, 0);
 	bh_unlock_sock(sk);
 
@@ -2602,9 +2808,60 @@ static inline void l2cap_sig_channel(struct l2cap_conn *conn, struct sk_buff *sk
 	kfree_skb(skb);
 }
 
+static inline int l2cap_data_channel_iframe(struct sock *sk, u16 rx_control, struct sk_buff *skb)
+{
+	struct l2cap_pinfo *pi = l2cap_pi(sk);
+	u8 tx_seq = __get_txseq(rx_control);
+	u16 tx_control = 0;
+	int err = 0;
+
+	BT_DBG("sk %p rx_control 0x%4.4x len %d", sk, rx_control, skb->len);
+
+	if (tx_seq != pi->expected_tx_seq)
+		return -EINVAL;
+
+	pi->expected_tx_seq = (pi->expected_tx_seq + 1) % 64;
+	err = sock_queue_rcv_skb(sk, skb);
+	if (err)
+		return err;
+
+	pi->num_to_ack = (pi->num_to_ack + 1) % L2CAP_DEFAULT_NUM_TO_ACK;
+	if (pi->num_to_ack == L2CAP_DEFAULT_NUM_TO_ACK - 1) {
+		tx_control |= L2CAP_CTRL_FRAME_TYPE;
+		tx_control |= L2CAP_SUPER_RCV_READY;
+		tx_control |= pi->expected_tx_seq << L2CAP_CTRL_REQSEQ_SHIFT;
+		err = l2cap_send_sframe(pi, tx_control);
+	}
+	return err;
+}
+
+static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, struct sk_buff *skb)
+{
+	struct l2cap_pinfo *pi = l2cap_pi(sk);
+
+	BT_DBG("sk %p rx_control 0x%4.4x len %d", sk, rx_control, skb->len);
+
+	switch (rx_control & L2CAP_CTRL_SUPERVISE) {
+	case L2CAP_SUPER_RCV_READY:
+		pi->expected_ack_seq = __get_reqseq(rx_control);
+		l2cap_drop_acked_frames(sk);
+		l2cap_ertm_send(sk);
+		break;
+
+	case L2CAP_SUPER_RCV_NOT_READY:
+	case L2CAP_SUPER_REJECT:
+	case L2CAP_SUPER_SELECT_REJECT:
+		break;
+	}
+
+	return 0;
+}
+
 static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk_buff *skb)
 {
 	struct sock *sk;
+	u16 control;
+	int err;
 
 	sk = l2cap_get_chan_by_scid(&conn->chan_list, cid);
 	if (!sk) {
@@ -2617,16 +2874,40 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
 	if (sk->sk_state != BT_CONNECTED)
 		goto drop;
 
-	if (l2cap_pi(sk)->imtu < skb->len)
-		goto drop;
+	switch (l2cap_pi(sk)->mode) {
+	case L2CAP_MODE_BASIC:
+		/* If socket recv buffers overflows we drop data here
+		 * which is *bad* because L2CAP has to be reliable.
+		 * But we don't have any other choice. L2CAP doesn't
+		 * provide flow control mechanism. */
 
-	/* If socket recv buffers overflows we drop data here
-	 * which is *bad* because L2CAP has to be reliable.
-	 * But we don't have any other choice. L2CAP doesn't
-	 * provide flow control mechanism. */
+		if (l2cap_pi(sk)->imtu < skb->len)
+			goto drop;
 
-	if (!sock_queue_rcv_skb(sk, skb))
-		goto done;
+		if (!sock_queue_rcv_skb(sk, skb))
+			goto done;
+		break;
+
+	case L2CAP_MODE_ERTM:
+		control = get_unaligned_le16(skb->data);
+		skb_pull(skb, 2);
+
+		if (l2cap_pi(sk)->imtu < skb->len)
+			goto drop;
+
+		if (__is_iframe(control))
+			err = l2cap_data_channel_iframe(sk, control, skb);
+		else
+			err = l2cap_data_channel_sframe(sk, control, skb);
+
+		if (!err)
+			goto done;
+		break;
+
+	default:
+		BT_DBG("sk %p: bad mode 0x%2.2x", sk, l2cap_pi(sk)->mode);
+		break;
+	}
 
 drop:
 	kfree_skb(skb);
@@ -2676,6 +2957,11 @@ static void l2cap_recv_frame(struct l2cap_conn *conn, struct sk_buff *skb)
 	cid = __le16_to_cpu(lh->cid);
 	len = __le16_to_cpu(lh->len);
 
+	if (len != skb->len) {
+		kfree_skb(skb);
+		return;
+	}
+
 	BT_DBG("len %d, cid 0x%4.4x", len, cid);
 
 	switch (cid) {