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Commit d2a7ac5d authored by Mat Martineau's avatar Mat Martineau Committed by Johan Hedberg
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Bluetooth: Add the ERTM receive state machine 

This adds a top-level state machine with handlers for two receive
states defined in the ERTM spec, RECV and SREJ_SENT.  The reqseq value
of the incoming frame is also validated at the top level and a
disconnection is forced if it is invalid.  The actions for the RECV
and SREJ_SENT states are implemented according to the state tables in
the ERTM specification.
Signed-off-by: default avatarMat Martineau <mathewm@codeaurora.org>
Signed-off-by: default avatarGustavo Padovan <gustavo.padovan@collabora.co.uk>
parent e31f7633
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Showing with 353 additions and 2 deletions
net/bluetooth/l2cap_core.c
View file @ d2a7ac5d
...@@ -1760,6 +1760,12 @@ static int l2cap_ertm_send(struct l2cap_chan *chan) ...@@ -1760,6 +1760,12 @@ static int l2cap_ertm_send(struct l2cap_chan *chan)
return sent; return sent;
} }
static void l2cap_retransmit_all(struct l2cap_chan *chan,
struct l2cap_ctrl *control)
{
/* Placeholder */
}
static void l2cap_send_ack(struct l2cap_chan *chan) static void l2cap_send_ack(struct l2cap_chan *chan)
{ {
struct l2cap_ctrl control; struct l2cap_ctrl control;
...@@ -2127,6 +2133,21 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len, ...@@ -2127,6 +2133,21 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len,
return err; return err;
} }
static void l2cap_send_srej(struct l2cap_chan *chan, u16 txseq)
{
/* Placeholder */
}
static void l2cap_send_srej_tail(struct l2cap_chan *chan)
{
/* Placeholder */
}
static void l2cap_send_srej_list(struct l2cap_chan *chan, u16 txseq)
{
/* Placeholder */
}
static void l2cap_process_reqseq(struct l2cap_chan *chan, u16 reqseq) static void l2cap_process_reqseq(struct l2cap_chan *chan, u16 reqseq)
{ {
struct sk_buff *acked_skb; struct sk_buff *acked_skb;
...@@ -4327,6 +4348,24 @@ void l2cap_chan_busy(struct l2cap_chan *chan, int busy) ...@@ -4327,6 +4348,24 @@ void l2cap_chan_busy(struct l2cap_chan *chan, int busy)
l2cap_tx(chan, 0, 0, event); l2cap_tx(chan, 0, 0, event);
} }
static int l2cap_rx_queued_iframes(struct l2cap_chan *chan)
{
/* Placeholder */
return 0;
}
static void l2cap_handle_srej(struct l2cap_chan *chan,
struct l2cap_ctrl *control)
{
/* Placeholder */
}
static void l2cap_handle_rej(struct l2cap_chan *chan,
struct l2cap_ctrl *control)
{
/* Placeholder */
}
static u8 l2cap_classify_txseq(struct l2cap_chan *chan, u16 txseq) static u8 l2cap_classify_txseq(struct l2cap_chan *chan, u16 txseq)
{ {
BT_DBG("chan %p, txseq %d", chan, txseq); BT_DBG("chan %p, txseq %d", chan, txseq);
...@@ -4414,11 +4453,323 @@ static u8 l2cap_classify_txseq(struct l2cap_chan *chan, u16 txseq) ...@@ -4414,11 +4453,323 @@ static u8 l2cap_classify_txseq(struct l2cap_chan *chan, u16 txseq)
} }
} }
static int l2cap_rx_state_recv(struct l2cap_chan *chan,
struct l2cap_ctrl *control,
struct sk_buff *skb, u8 event)
{
int err = 0;
bool skb_in_use = 0;
BT_DBG("chan %p, control %p, skb %p, event %d", chan, control, skb,
event);
switch (event) {
case L2CAP_EV_RECV_IFRAME:
switch (l2cap_classify_txseq(chan, control->txseq)) {
case L2CAP_TXSEQ_EXPECTED:
l2cap_pass_to_tx(chan, control);
if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
BT_DBG("Busy, discarding expected seq %d",
control->txseq);
break;
}
chan->expected_tx_seq = __next_seq(chan,
control->txseq);
chan->buffer_seq = chan->expected_tx_seq;
skb_in_use = 1;
err = l2cap_reassemble_sdu(chan, skb, control);
if (err)
break;
if (control->final) {
if (!test_and_clear_bit(CONN_REJ_ACT,
&chan->conn_state)) {
control->final = 0;
l2cap_retransmit_all(chan, control);
l2cap_ertm_send(chan);
}
}
if (!test_bit(CONN_LOCAL_BUSY, &chan->conn_state))
l2cap_send_ack(chan);
break;
case L2CAP_TXSEQ_UNEXPECTED:
l2cap_pass_to_tx(chan, control);
/* Can't issue SREJ frames in the local busy state.
* Drop this frame, it will be seen as missing
* when local busy is exited.
*/
if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
BT_DBG("Busy, discarding unexpected seq %d",
control->txseq);
break;
}
/* There was a gap in the sequence, so an SREJ
* must be sent for each missing frame. The
* current frame is stored for later use.
*/
skb_queue_tail(&chan->srej_q, skb);
skb_in_use = 1;
BT_DBG("Queued %p (queue len %d)", skb,
skb_queue_len(&chan->srej_q));
clear_bit(CONN_SREJ_ACT, &chan->conn_state);
l2cap_seq_list_clear(&chan->srej_list);
l2cap_send_srej(chan, control->txseq);
chan->rx_state = L2CAP_RX_STATE_SREJ_SENT;
break;
case L2CAP_TXSEQ_DUPLICATE:
l2cap_pass_to_tx(chan, control);
break;
case L2CAP_TXSEQ_INVALID_IGNORE:
break;
case L2CAP_TXSEQ_INVALID:
default:
l2cap_send_disconn_req(chan->conn, chan,
ECONNRESET);
break;
}
break;
case L2CAP_EV_RECV_RR:
l2cap_pass_to_tx(chan, control);
if (control->final) {
clear_bit(CONN_REMOTE_BUSY, &chan->conn_state);
if (!test_and_clear_bit(CONN_REJ_ACT,
&chan->conn_state)) {
control->final = 0;
l2cap_retransmit_all(chan, control);
}
l2cap_ertm_send(chan);
} else if (control->poll) {
l2cap_send_i_or_rr_or_rnr(chan);
} else {
if (test_and_clear_bit(CONN_REMOTE_BUSY,
&chan->conn_state) &&
chan->unacked_frames)
__set_retrans_timer(chan);
l2cap_ertm_send(chan);
}
break;
case L2CAP_EV_RECV_RNR:
set_bit(CONN_REMOTE_BUSY, &chan->conn_state);
l2cap_pass_to_tx(chan, control);
if (control && control->poll) {
set_bit(CONN_SEND_FBIT, &chan->conn_state);
l2cap_send_rr_or_rnr(chan, 0);
}
__clear_retrans_timer(chan);
l2cap_seq_list_clear(&chan->retrans_list);
break;
case L2CAP_EV_RECV_REJ:
l2cap_handle_rej(chan, control);
break;
case L2CAP_EV_RECV_SREJ:
l2cap_handle_srej(chan, control);
break;
default:
break;
}
if (skb && !skb_in_use) {
BT_DBG("Freeing %p", skb);
kfree_skb(skb);
}
return err;
}
static int l2cap_rx_state_srej_sent(struct l2cap_chan *chan,
struct l2cap_ctrl *control,
struct sk_buff *skb, u8 event)
{
int err = 0;
u16 txseq = control->txseq;
bool skb_in_use = 0;
BT_DBG("chan %p, control %p, skb %p, event %d", chan, control, skb,
event);
switch (event) {
case L2CAP_EV_RECV_IFRAME:
switch (l2cap_classify_txseq(chan, txseq)) {
case L2CAP_TXSEQ_EXPECTED:
/* Keep frame for reassembly later */
l2cap_pass_to_tx(chan, control);
skb_queue_tail(&chan->srej_q, skb);
skb_in_use = 1;
BT_DBG("Queued %p (queue len %d)", skb,
skb_queue_len(&chan->srej_q));
chan->expected_tx_seq = __next_seq(chan, txseq);
break;
case L2CAP_TXSEQ_EXPECTED_SREJ:
l2cap_seq_list_pop(&chan->srej_list);
l2cap_pass_to_tx(chan, control);
skb_queue_tail(&chan->srej_q, skb);
skb_in_use = 1;
BT_DBG("Queued %p (queue len %d)", skb,
skb_queue_len(&chan->srej_q));
err = l2cap_rx_queued_iframes(chan);
if (err)
break;
break;
case L2CAP_TXSEQ_UNEXPECTED:
/* Got a frame that can't be reassembled yet.
* Save it for later, and send SREJs to cover
* the missing frames.
*/
skb_queue_tail(&chan->srej_q, skb);
skb_in_use = 1;
BT_DBG("Queued %p (queue len %d)", skb,
skb_queue_len(&chan->srej_q));
l2cap_pass_to_tx(chan, control);
l2cap_send_srej(chan, control->txseq);
break;
case L2CAP_TXSEQ_UNEXPECTED_SREJ:
/* This frame was requested with an SREJ, but
* some expected retransmitted frames are
* missing. Request retransmission of missing
* SREJ'd frames.
*/
skb_queue_tail(&chan->srej_q, skb);
skb_in_use = 1;
BT_DBG("Queued %p (queue len %d)", skb,
skb_queue_len(&chan->srej_q));
l2cap_pass_to_tx(chan, control);
l2cap_send_srej_list(chan, control->txseq);
break;
case L2CAP_TXSEQ_DUPLICATE_SREJ:
/* We've already queued this frame. Drop this copy. */
l2cap_pass_to_tx(chan, control);
break;
case L2CAP_TXSEQ_DUPLICATE:
/* Expecting a later sequence number, so this frame
* was already received. Ignore it completely.
*/
break;
case L2CAP_TXSEQ_INVALID_IGNORE:
break;
case L2CAP_TXSEQ_INVALID:
default:
l2cap_send_disconn_req(chan->conn, chan,
ECONNRESET);
break;
}
break;
case L2CAP_EV_RECV_RR:
l2cap_pass_to_tx(chan, control);
if (control->final) {
clear_bit(CONN_REMOTE_BUSY, &chan->conn_state);
if (!test_and_clear_bit(CONN_REJ_ACT,
&chan->conn_state)) {
control->final = 0;
l2cap_retransmit_all(chan, control);
}
l2cap_ertm_send(chan);
} else if (control->poll) {
if (test_and_clear_bit(CONN_REMOTE_BUSY,
&chan->conn_state) &&
chan->unacked_frames) {
__set_retrans_timer(chan);
}
set_bit(CONN_SEND_FBIT, &chan->conn_state);
l2cap_send_srej_tail(chan);
} else {
if (test_and_clear_bit(CONN_REMOTE_BUSY,
&chan->conn_state) &&
chan->unacked_frames)
__set_retrans_timer(chan);
l2cap_send_ack(chan);
}
break;
case L2CAP_EV_RECV_RNR:
set_bit(CONN_REMOTE_BUSY, &chan->conn_state);
l2cap_pass_to_tx(chan, control);
if (control->poll) {
l2cap_send_srej_tail(chan);
} else {
struct l2cap_ctrl rr_control;
memset(&rr_control, 0, sizeof(rr_control));
rr_control.sframe = 1;
rr_control.super = L2CAP_SUPER_RR;
rr_control.reqseq = chan->buffer_seq;
l2cap_send_sframe(chan, &rr_control);
}
break;
case L2CAP_EV_RECV_REJ:
l2cap_handle_rej(chan, control);
break;
case L2CAP_EV_RECV_SREJ:
l2cap_handle_srej(chan, control);
break;
}
if (skb && !skb_in_use) {
BT_DBG("Freeing %p", skb);
kfree_skb(skb);
}
return err;
}
static bool __valid_reqseq(struct l2cap_chan *chan, u16 reqseq)
{
/* Make sure reqseq is for a packet that has been sent but not acked */
u16 unacked;
unacked = __seq_offset(chan, chan->next_tx_seq, chan->expected_ack_seq);
return __seq_offset(chan, chan->next_tx_seq, reqseq) <= unacked;
}
static int l2cap_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control, static int l2cap_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
struct sk_buff *skb, u8 event) struct sk_buff *skb, u8 event)
{ {
/* Placeholder */ int err = 0;
return -ENOTSUPP;
BT_DBG("chan %p, control %p, skb %p, event %d, state %d", chan,
control, skb, event, chan->rx_state);
if (__valid_reqseq(chan, control->reqseq)) {
switch (chan->rx_state) {
case L2CAP_RX_STATE_RECV:
err = l2cap_rx_state_recv(chan, control, skb, event);
break;
case L2CAP_RX_STATE_SREJ_SENT:
err = l2cap_rx_state_srej_sent(chan, control, skb,
event);
break;
default:
/* shut it down */
break;
}
} else {
BT_DBG("Invalid reqseq %d (next_tx_seq %d, expected_ack_seq %d",
control->reqseq, chan->next_tx_seq,
chan->expected_ack_seq);
l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
}
return err;
} }
static int l2cap_stream_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control, static int l2cap_stream_rx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
......
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