From d2a7ac5d5d3a0b166ac128883bd088064c029fe5 Mon Sep 17 00:00:00 2001 From: Mat Martineau Date: Thu, 17 May 2012 20:53:42 -0700 Subject: [PATCH] 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: Mat Martineau Signed-off-by: Gustavo Padovan --- net/bluetooth/l2cap_core.c | 355 ++++++++++++++++++++++++++++++++++++- 1 file changed, 353 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index a7d96c93739..287d64cf2dd 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -1760,6 +1760,12 @@ static int l2cap_ertm_send(struct l2cap_chan *chan) 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) { struct l2cap_ctrl control; @@ -2127,6 +2133,21 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len, 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) { struct sk_buff *acked_skb; @@ -4327,6 +4348,24 @@ void l2cap_chan_busy(struct l2cap_chan *chan, int busy) 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) { BT_DBG("chan %p, txseq %d", chan, 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, struct sk_buff *skb, u8 event) { - /* Placeholder */ - return -ENOTSUPP; + int err = 0; + + 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, -- 2.41.0