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extmod/modbluetooth: Add API for L2CAP channels.

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Also known as L2CAP "connection oriented channels". This provides a
socket-like data transfer mechanism for BLE.

Currently only implemented for NimBLE on STM32 / Unix.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit is contained in:
Jim Mussared
2020-10-16 00:15:16 +11:00
committed by Damien George
parent 64180f0742
commit 0e8af2b370
9 changed files with 504 additions and 22 deletions
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332
extmod/nimble/modbluetooth_nimble.c
View File

@@ -42,6 +42,10 @@
#include "services/gap/ble_svc_gap.h"
#include "services/gatt/ble_svc_gatt.h"
// We need the definition of "struct ble_l2cap_chan".
// See l2cap_channel_event() for details.
#include "nimble/host/src/ble_l2cap_priv.h"
#ifndef MICROPY_PY_BLUETOOTH_DEFAULT_GAP_NAME
#define MICROPY_PY_BLUETOOTH_DEFAULT_GAP_NAME "MPY NIMBLE"
#endif
@@ -66,6 +70,7 @@ STATIC int8_t ble_hs_err_to_errno_table[] = {
[BLE_HS_ETIMEOUT] = MP_ETIMEDOUT,
[BLE_HS_EDONE] = MP_EIO, // TODO: Maybe should be MP_EISCONN (connect uses this for "already connected").
[BLE_HS_EBUSY] = MP_EBUSY,
[BLE_HS_EBADDATA] = MP_EINVAL,
};
STATIC int ble_hs_err_to_errno(int err) {
@@ -1110,4 +1115,331 @@ int mp_bluetooth_gattc_exchange_mtu(uint16_t conn_handle) {
#endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
#if MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
// Fortunately NimBLE uses mbuf chains correctly with L2CAP COC (rather than
// accessing the mbuf internals directly), so we can use a small block size to
// avoid excessive fragmentation and rely on them chaining together for larger
// payloads.
#define L2CAP_BUF_BLOCK_SIZE (128)
// This gives us enough room to have one MTU-size transmit buffer and two
// MTU-sized receive buffers. Note that we use the local MTU to calculate
// the buffer size. This means that if the peer MTU is larger, then
// there might not be enough space in the pool to send a full peer-MTU
// sized payload and mp_bluetooth_l2cap_send will return ENOMEM.
#define L2CAP_BUF_SIZE_MTUS_PER_CHANNEL (3)
typedef struct _mp_bluetooth_nimble_l2cap_channel_t {
struct ble_l2cap_chan *chan;
struct os_mbuf_pool sdu_mbuf_pool;
struct os_mempool sdu_mempool;
struct os_mbuf *rx_pending;
uint16_t mtu;
os_membuf_t sdu_mem[];
} mp_bluetooth_nimble_l2cap_channel_t;
STATIC void destroy_l2cap_channel() {
// Only free the l2cap channel if we're the one that initiated the connection.
// Listeners continue listening on the same channel.
if (!MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_listening) {
MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_chan = NULL;
}
}
STATIC int l2cap_channel_event(struct ble_l2cap_event *event, void *arg) {
DEBUG_printf("l2cap_channel_event: type=%d\n", event->type);
mp_bluetooth_nimble_l2cap_channel_t *chan = (mp_bluetooth_nimble_l2cap_channel_t *)arg;
struct ble_l2cap_chan_info info;
switch (event->type) {
case BLE_L2CAP_EVENT_COC_CONNECTED: {
DEBUG_printf("l2cap_channel_event: connect: conn_handle=%d status=%d\n", event->connect.conn_handle, event->connect.status);
chan->chan = event->connect.chan;
ble_l2cap_get_chan_info(event->connect.chan, &info);
if (event->connect.status == 0) {
mp_bluetooth_gattc_on_l2cap_connect(event->connect.conn_handle, info.scid, info.psm, info.our_coc_mtu, info.peer_coc_mtu);
} else {
mp_bluetooth_gattc_on_l2cap_disconnect(event->connect.conn_handle, info.scid, info.psm, event->connect.status);
destroy_l2cap_channel();
}
break;
}
case BLE_L2CAP_EVENT_COC_DISCONNECTED: {
DEBUG_printf("l2cap_channel_event: disconnect: conn_handle=%d\n", event->disconnect.conn_handle);
ble_l2cap_get_chan_info(event->disconnect.chan, &info);
mp_bluetooth_gattc_on_l2cap_disconnect(event->disconnect.conn_handle, info.scid, info.psm, 0);
destroy_l2cap_channel();
break;
}
case BLE_L2CAP_EVENT_COC_ACCEPT: {
DEBUG_printf("l2cap_channel_event: accept: conn_handle=%d peer_sdu_size=%d\n", event->accept.conn_handle, event->accept.peer_sdu_size);
chan->chan = event->accept.chan;
ble_l2cap_get_chan_info(event->accept.chan, &info);
int ret = mp_bluetooth_gattc_on_l2cap_accept(event->accept.conn_handle, info.scid, info.psm, info.our_coc_mtu, info.peer_coc_mtu);
if (ret != 0) {
return ret;
}
struct os_mbuf *sdu_rx = os_mbuf_get_pkthdr(&chan->sdu_mbuf_pool, 0);
assert(sdu_rx);
return ble_l2cap_recv_ready(chan->chan, sdu_rx);
}
case BLE_L2CAP_EVENT_COC_DATA_RECEIVED: {
DEBUG_printf("l2cap_channel_event: receive: conn_handle=%d len=%d\n", event->receive.conn_handle, OS_MBUF_PKTLEN(event->receive.sdu_rx));
if (chan->rx_pending) {
// Ideally this doesn't happen, as the sender should not get
// any more credits to send more data until we call
// ble_l2cap_recv_ready. However there might be multiple
// in-flight packets if the sender was able to send more than
// one before stalling.
DEBUG_printf("l2cap_channel_event: receive: appending to rx pending\n");
// Note: os_mbuf_concat will just join the two together, so
// sdu_rx is now "owned" by rx_pending.
os_mbuf_concat(chan->rx_pending, event->receive.sdu_rx);
} else {
// Normal case is when the first payload arrives since calling
// ble_l2cap_recv_ready.
DEBUG_printf("l2cap_event: receive: new payload\n");
// Take ownership of sdu_rx.
chan->rx_pending = event->receive.sdu_rx;
}
struct os_mbuf *sdu_rx = os_mbuf_get_pkthdr(&chan->sdu_mbuf_pool, 0);
assert(sdu_rx);
// ble_l2cap_coc_rx_fn invokes this event handler when a complete payload arrives.
// However, it NULLs chan->chan->coc_rx.sdu before doing so, expecting that
// ble_l2cap_recv_ready will be called to give it a new mbuf.
// This means that if another payload arrives before we call ble_l2cap_recv_ready
// then ble_l2cap_coc_rx_fn will NULL-deref coc_rx.sdu.
// Because we're not yet ready to grant new credits to the channel, we can't call
// ble_l2cap_recv_ready yet, so instead we just give it a new mbuf. This requires
// ble_l2cap_priv.h for the definition of chan->chan (i.e. struct ble_l2cap_chan).
chan->chan->coc_rx.sdu = sdu_rx;
ble_l2cap_get_chan_info(event->receive.chan, &info);
mp_bluetooth_gattc_on_l2cap_recv(event->receive.conn_handle, info.scid);
break;
}
case BLE_L2CAP_EVENT_COC_TX_UNSTALLED: {
DEBUG_printf("l2cap_channel_event: tx_unstalled: conn_handle=%d status=%d\n", event->tx_unstalled.conn_handle, event->tx_unstalled.status);
ble_l2cap_get_chan_info(event->receive.chan, &info);
// Map status to {0,1} (i.e. "sent everything", or "partial send").
mp_bluetooth_gattc_on_l2cap_send_ready(event->tx_unstalled.conn_handle, info.scid, event->tx_unstalled.status == 0 ? 0 : 1);
break;
}
case BLE_L2CAP_EVENT_COC_RECONFIG_COMPLETED: {
DEBUG_printf("l2cap_channel_event: reconfig_completed: conn_handle=%d\n", event->reconfigured.conn_handle);
break;
}
case BLE_L2CAP_EVENT_COC_PEER_RECONFIGURED: {
DEBUG_printf("l2cap_channel_event: peer_reconfigured: conn_handle=%d\n", event->reconfigured.conn_handle);
break;
}
default: {
DEBUG_printf("l2cap_channel_event: unknown event\n");
break;
}
}
return 0;
}
STATIC mp_bluetooth_nimble_l2cap_channel_t *get_l2cap_channel_for_conn_cid(uint16_t conn_handle, uint16_t cid) {
// TODO: Support more than one concurrent L2CAP channel. At the moment we
// just verify that the cid refers to the current channel.
mp_bluetooth_nimble_l2cap_channel_t *chan = MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_chan;
if (!chan) {
return NULL;
}
struct ble_l2cap_chan_info info;
ble_l2cap_get_chan_info(chan->chan, &info);
if (info.scid != cid || ble_l2cap_get_conn_handle(chan->chan) != conn_handle) {
return NULL;
}
return chan;
}
STATIC int create_l2cap_channel(uint16_t mtu, mp_bluetooth_nimble_l2cap_channel_t **out) {
if (MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_chan) {
// Only one L2CAP channel allowed.
// Additionally, if we're listening, then no connections may be initiated.
DEBUG_printf("create_l2cap_channel: channel already in use\n");
return MP_EALREADY;
}
// We want the TX and RX buffers to share a pool that is some multiple of
// the MTU size. Figure out how many blocks per MTU (rounding up), then
// multiply that by the "MTUs per channel" (set to 3 above).
const size_t buf_blocks = MP_CEIL_DIVIDE(mtu, L2CAP_BUF_BLOCK_SIZE) * L2CAP_BUF_SIZE_MTUS_PER_CHANNEL;
mp_bluetooth_nimble_l2cap_channel_t *chan = m_new_obj_var(mp_bluetooth_nimble_l2cap_channel_t, uint8_t, OS_MEMPOOL_SIZE(buf_blocks, L2CAP_BUF_BLOCK_SIZE) * sizeof(os_membuf_t));
MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_chan = chan;
// Will be set in BLE_L2CAP_EVENT_COC_CONNECTED or BLE_L2CAP_EVENT_COC_ACCEPT.
chan->chan = NULL;
chan->mtu = mtu;
chan->rx_pending = NULL;
int err = os_mempool_init(&chan->sdu_mempool, buf_blocks, L2CAP_BUF_BLOCK_SIZE, chan->sdu_mem, "l2cap_sdu_pool");
if (err != 0) {
DEBUG_printf("mp_bluetooth_l2cap_connect: os_mempool_init failed %d\n", err);
return MP_ENOMEM;
}
err = os_mbuf_pool_init(&chan->sdu_mbuf_pool, &chan->sdu_mempool, L2CAP_BUF_BLOCK_SIZE, buf_blocks);
if (err != 0) {
DEBUG_printf("mp_bluetooth_l2cap_connect: os_mbuf_pool_init failed %d\n", err);
return MP_ENOMEM;
}
*out = chan;
return 0;
}
int mp_bluetooth_l2cap_listen(uint16_t psm, uint16_t mtu) {
DEBUG_printf("mp_bluetooth_l2cap_listen: psm=%d, mtu=%d\n", psm, mtu);
mp_bluetooth_nimble_l2cap_channel_t *chan;
int err = create_l2cap_channel(mtu, &chan);
if (err != 0) {
return err;
}
MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_listening = true;
return ble_hs_err_to_errno(ble_l2cap_create_server(psm, mtu, &l2cap_channel_event, chan));
}
int mp_bluetooth_l2cap_connect(uint16_t conn_handle, uint16_t psm, uint16_t mtu) {
DEBUG_printf("mp_bluetooth_l2cap_connect: conn_handle=%d, psm=%d, mtu=%d\n", conn_handle, psm, mtu);
mp_bluetooth_nimble_l2cap_channel_t *chan;
int err = create_l2cap_channel(mtu, &chan);
if (err != 0) {
return err;
}
struct os_mbuf *sdu_rx = os_mbuf_get_pkthdr(&chan->sdu_mbuf_pool, 0);
assert(sdu_rx);
return ble_hs_err_to_errno(ble_l2cap_connect(conn_handle, psm, mtu, sdu_rx, &l2cap_channel_event, chan));
}
int mp_bluetooth_l2cap_disconnect(uint16_t conn_handle, uint16_t cid) {
DEBUG_printf("mp_bluetooth_l2cap_disconnect: conn_handle=%d, cid=%d\n", conn_handle, cid);
mp_bluetooth_nimble_l2cap_channel_t *chan = get_l2cap_channel_for_conn_cid(conn_handle, cid);
if (!chan) {
return MP_EINVAL;
}
return ble_hs_err_to_errno(ble_l2cap_disconnect(chan->chan));
}
int mp_bluetooth_l2cap_send(uint16_t conn_handle, uint16_t cid, const uint8_t *buf, size_t len, bool *stalled) {
DEBUG_printf("mp_bluetooth_l2cap_send: conn_handle=%d, cid=%d, len=%d\n", conn_handle, cid, (int)len);
mp_bluetooth_nimble_l2cap_channel_t *chan = get_l2cap_channel_for_conn_cid(conn_handle, cid);
if (!chan) {
return MP_EINVAL;
}
struct ble_l2cap_chan_info info;
ble_l2cap_get_chan_info(chan->chan, &info);
if (len > info.peer_coc_mtu) {
// This is verified by ble_l2cap_send anyway, but this lets us
// avoid copying a too-large buffer into an mbuf.
return MP_EINVAL;
}
if (len > (L2CAP_BUF_SIZE_MTUS_PER_CHANNEL - 1) * info.our_coc_mtu) {
// Always ensure there's at least one local MTU of space left in the buffer
// for the RX buffer.
return MP_EINVAL;
}
// Grab an mbuf from the pool, and append the incoming buffer to it.
struct os_mbuf *sdu_tx = os_mbuf_get_pkthdr(&chan->sdu_mbuf_pool, 0);
if (sdu_tx == NULL) {
return MP_ENOMEM;
}
int err = os_mbuf_append(sdu_tx, buf, len);
if (err) {
os_mbuf_free_chain(sdu_tx);
return MP_ENOMEM;
}
err = ble_l2cap_send(chan->chan, sdu_tx);
if (err == BLE_HS_ESTALLED) {
// Stalled means that this one will still send but any future ones
// will fail until we receive an unstalled event.
*stalled = true;
err = 0;
} else {
*stalled = false;
}
// Other error codes such as BLE_HS_EBUSY (we're stalled) or BLE_HS_EBADDATA (bigger than MTU).
return ble_hs_err_to_errno(err);
}
int mp_bluetooth_l2cap_recvinto(uint16_t conn_handle, uint16_t cid, uint8_t *buf, size_t *len) {
mp_bluetooth_nimble_l2cap_channel_t *chan = get_l2cap_channel_for_conn_cid(conn_handle, cid);
if (!chan) {
return MP_EINVAL;
}
MICROPY_PY_BLUETOOTH_ENTER
if (chan->rx_pending) {
size_t avail = OS_MBUF_PKTLEN(chan->rx_pending);
if (buf == NULL) {
// Can use this to implement a poll - just find out how much is available.
*len = avail;
} else {
// Have dest buffer and data available.
// Figure out how much we should copy.
*len = min(*len, avail);
// Extract the required number of bytes.
os_mbuf_copydata(chan->rx_pending, 0, *len, buf);
if (*len == avail) {
// That's all that's available -- free this mbuf and re-enable receiving.
os_mbuf_free_chain(chan->rx_pending);
chan->rx_pending = NULL;
// We've already given the channel a new mbuf in l2cap_channel_event above, so
// re-use that mbuf in the call to ble_l2cap_recv_ready. This will just
// give the channel more credits.
struct os_mbuf *sdu_rx = chan->chan->coc_rx.sdu;
assert(sdu_rx);
if (sdu_rx) {
ble_l2cap_recv_ready(chan->chan, sdu_rx);
}
} else {
// Trim the used bytes from the start of the mbuf.
// Positive argument means "trim this many from head".
os_mbuf_adj(chan->rx_pending, *len);
// Clean up any empty mbufs at the head.
chan->rx_pending = os_mbuf_trim_front(chan->rx_pending);
}
}
} else {
// No pending data.
*len = 0;
}
MICROPY_PY_BLUETOOTH_EXIT
return 0;
}
#endif // MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
#endif // MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_NIMBLE

6
extmod/nimble/modbluetooth_nimble.h
View File

@@ -38,6 +38,12 @@ typedef struct _mp_bluetooth_nimble_root_pointers_t {
// Pending service definitions.
size_t n_services;
struct ble_gatt_svc_def *services[MP_BLUETOOTH_NIMBLE_MAX_SERVICES];
#if MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
// L2CAP channels.
struct _mp_bluetooth_nimble_l2cap_channel_t *l2cap_chan;
bool l2cap_listening;
#endif
} mp_bluetooth_nimble_root_pointers_t;
enum {

13
extmod/nimble/nimble/nimble_npl_os.h
View File

@@ -30,12 +30,25 @@
// This is included by nimble/nimble_npl.h -- include that rather than this file directly.
#include <stdint.h>
#include <limits.h>
// --- Configuration of NimBLE data structures --------------------------------
// This is used at runtime to align allocations correctly.
#define BLE_NPL_OS_ALIGNMENT (sizeof(uintptr_t))
#define BLE_NPL_TIME_FOREVER (0xffffffff)
// This is used at compile time to force struct member alignment. See
// os_mempool.h for where this is used (none of these three macros are defined
// by default).
#define OS_CFG_ALIGN_4 (4)
#define OS_CFG_ALIGN_8 (8)
#if (ULONG_MAX == 0xffffffffffffffff)
#define OS_CFG_ALIGNMENT (OS_CFG_ALIGN_8)
#else
#define OS_CFG_ALIGNMENT (OS_CFG_ALIGN_4)
#endif
typedef uint32_t ble_npl_time_t;
typedef int32_t ble_npl_stime_t;

6
extmod/nimble/syscfg/syscfg.h
View File

@@ -99,9 +99,11 @@ int nimble_sprintf(char *str, const char *fmt, ...);
#define MYNEWT_VAL_BLE_HS_PHONY_HCI_ACKS (0)
#define MYNEWT_VAL_BLE_HS_REQUIRE_OS (1)
#define MYNEWT_VAL_BLE_HS_STOP_ON_SHUTDOWN_TIMEOUT (2000)
#define MYNEWT_VAL_BLE_L2CAP_COC_MAX_NUM (0)
#define MYNEWT_VAL_BLE_L2CAP_COC_MAX_NUM (1)
#define MYNEWT_VAL_BLE_L2CAP_COC_MPS (MYNEWT_VAL_MSYS_1_BLOCK_SIZE - 8)
#define MYNEWT_VAL_BLE_L2CAP_ENHANCED_COC (0)
#define MYNEWT_VAL_BLE_L2CAP_JOIN_RX_FRAGS (1)
#define MYNEWT_VAL_BLE_L2CAP_MAX_CHANS (3*MYNEWT_VAL_BLE_MAX_CONNECTIONS)
#define MYNEWT_VAL_BLE_L2CAP_MAX_CHANS (3 * MYNEWT_VAL_BLE_MAX_CONNECTIONS)
#define MYNEWT_VAL_BLE_L2CAP_RX_FRAG_TIMEOUT (30000)
#define MYNEWT_VAL_BLE_L2CAP_SIG_MAX_PROCS (1)
#define MYNEWT_VAL_BLE_MONITOR_CONSOLE_BUFFER_SIZE (128)