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Commit 2c5dcdf8 authored by Jakub Pawlowski's avatar Jakub Pawlowski
Browse files

Maximize L2CAP socket MTU 

Introduce L2CAP_SDU_LENGTH_LE_MAX constant, and use it for LE CoC
sockets, while still keeping the old value for Classic sockets.

This also require change in how we send the rx_mtu up the stack - it
must be read from the socket property.

Additionally in this patch, l2cap_socket.mtu is renamed to tx_mtu to
distinguish it from rx_mtu. Assignment of this variable is also added
when we receive it from the remote.

Bug: 68359837
Test: tranfer file using OPP, do obex, run LE CoC tests. Run tests
between device with this patch, and older android phones.
Change-Id: Iffa20a6c6a93d5787bada7bf28655e9880d8c1a0
parent 8cd20068

system/btif/src/btif_sock_l2cap.cc

+101 −99
Original line number Diff line number Diff line
@@ -84,7 +84,8 @@ typedef struct l2cap_socket { 
  unsigned outgoing_congest : 1;  // should we hold?

  unsigned server_psm_sent : 1;   // The server shall only send PSM once.

  bool is_le_coc;                 // is le connection oriented channel?

  uint16_t mtu;

  uint16_t rx_mtu;

  uint16_t tx_mtu;

} l2cap_socket;



static void btsock_l2cap_server_listen(l2cap_socket* sock);
@@ -310,7 +311,7 @@ static l2cap_socket* btsock_l2cap_alloc_l(const char* name, 
  sock->first_packet = NULL;

  sock->last_packet = NULL;



  sock->mtu = L2CAP_LE_MIN_MTU;

  sock->tx_mtu = L2CAP_LE_MIN_MTU;



  sock->next = socks;

  sock->prev = NULL;
@@ -362,13 +363,14 @@ static inline bool send_app_psm_or_chan_l(l2cap_socket* sock) { 
}



static bool send_app_connect_signal(int fd, const RawAddress* addr, int channel,

                                    int status, int send_fd, int tx_mtu) {

                                    int status, int send_fd, uint16_t rx_mtu,

                                    uint16_t tx_mtu) {

  sock_connect_signal_t cs;

  cs.size = sizeof(cs);

  cs.bd_addr = *addr;

  cs.channel = channel;

  cs.status = status;

  cs.max_rx_packet_size = L2CAP_MAX_SDU_LENGTH;

  cs.max_rx_packet_size = rx_mtu;

  cs.max_tx_packet_size = tx_mtu;

  if (send_fd != -1) {

    if (sock_send_fd(fd, (const uint8_t*)&cs, sizeof(cs), send_fd) ==
@@ -433,11 +435,10 @@ static void on_cl_l2cap_init(tBTA_JV_L2CAP_CL_INIT* p_init, uint32_t id) { 
 * */

static void on_srv_l2cap_psm_connect_l(tBTA_JV_L2CAP_OPEN* p_open,

                                       l2cap_socket* sock) {

  l2cap_socket* accept_rs;

  uint32_t new_listen_id;



  // std::mutex locked by caller

  accept_rs = btsock_l2cap_alloc_l(sock->name, &p_open->rem_bda, false, 0);

  l2cap_socket* accept_rs =

      btsock_l2cap_alloc_l(sock->name, &p_open->rem_bda, false, 0);

  accept_rs->connected = true;

  accept_rs->security = sock->security;

  accept_rs->fixed_chan = sock->fixed_chan;
@@ -447,46 +448,42 @@ static void on_srv_l2cap_psm_connect_l(tBTA_JV_L2CAP_OPEN* p_open, 
  sock->handle =

      -1; /* We should no longer associate this handle with the server socket */

  accept_rs->is_le_coc = sock->is_le_coc;

  accept_rs->mtu = sock->mtu;

  accept_rs->tx_mtu = sock->tx_mtu = p_open->tx_mtu;



  /* Swap IDs to hand over the GAP connection to the accepted socket, and start

     a new server on

     the newly create socket ID. */

  new_listen_id = accept_rs->id;

     a new server on the newly create socket ID. */

  uint32_t new_listen_id = accept_rs->id;

  accept_rs->id = sock->id;

  sock->id = new_listen_id;



  if (accept_rs) {

  // start monitor the socket

  btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP,

                       SOCK_THREAD_FD_EXCEPTION, sock->id);

    btsock_thread_add_fd(pth, accept_rs->our_fd, BTSOCK_L2CAP,

                         SOCK_THREAD_FD_RD, accept_rs->id);

  btsock_thread_add_fd(pth, accept_rs->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,

                       accept_rs->id);

  APPL_TRACE_DEBUG(

      "sending connect signal & app fd: %d to app server to accept() the "

      "connection",

      accept_rs->app_fd);

  APPL_TRACE_DEBUG("server fd:%d, scn:%d", sock->our_fd, sock->channel);

  send_app_connect_signal(sock->our_fd, &accept_rs->addr, sock->channel, 0,

                            accept_rs->app_fd, p_open->tx_mtu);

                          accept_rs->app_fd, sock->rx_mtu, p_open->tx_mtu);

  accept_rs->app_fd =

      -1;  // The fd is closed after sent to app in send_app_connect_signal()

  // But for some reason we still leak a FD - either the server socket

  // one or the accept socket one.

  btsock_l2cap_server_listen(sock);

}

}



static void on_srv_l2cap_le_connect_l(tBTA_JV_L2CAP_LE_OPEN* p_open,

                                      l2cap_socket* sock) {

  l2cap_socket* accept_rs;

  uint32_t new_listen_id;



  // std::mutex locked by caller

  accept_rs = btsock_l2cap_alloc_l(sock->name, &p_open->rem_bda, false, 0);

  if (accept_rs) {

  l2cap_socket* accept_rs =

      btsock_l2cap_alloc_l(sock->name, &p_open->rem_bda, false, 0);

  if (!accept_rs) return;



  // swap IDs

    new_listen_id = accept_rs->id;

  uint32_t new_listen_id = accept_rs->id;

  accept_rs->id = sock->id;

  sock->id = new_listen_id;
@@ -496,7 +493,7 @@ static void on_srv_l2cap_le_connect_l(tBTA_JV_L2CAP_LE_OPEN* p_open, 
  accept_rs->fixed_chan = sock->fixed_chan;

  accept_rs->channel = sock->channel;

  accept_rs->app_uid = sock->app_uid;

    accept_rs->mtu = sock->mtu;

  accept_rs->tx_mtu = sock->tx_mtu = p_open->tx_mtu;



  // if we do not set a callback, this socket will be dropped */

  *(p_open->p_p_cback) = (void*)btsock_l2cap_cbk;
@@ -505,30 +502,34 @@ static void on_srv_l2cap_le_connect_l(tBTA_JV_L2CAP_LE_OPEN* p_open, 
  // start monitor the socket

  btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP,

                       SOCK_THREAD_FD_EXCEPTION, sock->id);

    btsock_thread_add_fd(pth, accept_rs->our_fd, BTSOCK_L2CAP,

                         SOCK_THREAD_FD_RD, accept_rs->id);

  btsock_thread_add_fd(pth, accept_rs->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,

                       accept_rs->id);

  APPL_TRACE_DEBUG(

      "sending connect signal & app fd:%dto app server to accept() the "

      "connection",

      accept_rs->app_fd);

  APPL_TRACE_DEBUG("server fd:%d, scn:%d", sock->our_fd, sock->channel);

  send_app_connect_signal(sock->our_fd, &accept_rs->addr, sock->channel, 0,

                            accept_rs->app_fd, p_open->tx_mtu);

                          accept_rs->app_fd, sock->rx_mtu, p_open->tx_mtu);

  accept_rs->app_fd = -1;  // the fd is closed after sent to app

}

}



static void on_cl_l2cap_psm_connect_l(tBTA_JV_L2CAP_OPEN* p_open,

                                      l2cap_socket* sock) {

  sock->addr = p_open->rem_bda;

  sock->tx_mtu = p_open->tx_mtu;



  if (!send_app_psm_or_chan_l(sock)) {

    APPL_TRACE_ERROR("send_app_psm_or_chan_l failed");

    return;

  }



  if (send_app_connect_signal(sock->our_fd, &sock->addr, sock->channel, 0, -1,

                              p_open->tx_mtu)) {

  if (!send_app_connect_signal(sock->our_fd, &sock->addr, sock->channel, 0, -1,

                               sock->rx_mtu, p_open->tx_mtu)) {

    APPL_TRACE_ERROR("send_app_connect_signal failed");

    return;

  }



  // start monitoring the socketpair to get call back when app writing data

  APPL_TRACE_DEBUG(

      "on_l2cap_connect_ind, connect signal sent, slot id:%d, psm:%d, "
@@ -537,21 +538,24 @@ static void on_cl_l2cap_psm_connect_l(tBTA_JV_L2CAP_OPEN* p_open, 
  btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,

                       sock->id);

  sock->connected = true;

  } else

    APPL_TRACE_ERROR("send_app_connect_signal failed");

}



static void on_cl_l2cap_le_connect_l(tBTA_JV_L2CAP_LE_OPEN* p_open,

                                     l2cap_socket* sock) {

  sock->addr = p_open->rem_bda;

  sock->tx_mtu = p_open->tx_mtu;



  if (!send_app_psm_or_chan_l(sock)) {

    APPL_TRACE_ERROR("send_app_psm_or_chan_l failed");

    return;

  }



  if (send_app_connect_signal(sock->our_fd, &sock->addr, sock->channel, 0, -1,

                              p_open->tx_mtu)) {

  if (!send_app_connect_signal(sock->our_fd, &sock->addr, sock->channel, 0, -1,

                               sock->rx_mtu, p_open->tx_mtu)) {

    APPL_TRACE_ERROR("send_app_connect_signal failed");

    return;

  }



  // start monitoring the socketpair to get call back when app writing data

  APPL_TRACE_DEBUG(

      "on_l2cap_connect_ind, connect signal sent, slot id:%d, Chan:%d, "
@@ -560,8 +564,6 @@ static void on_cl_l2cap_le_connect_l(tBTA_JV_L2CAP_LE_OPEN* p_open, 
  btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,

                       sock->id);

  sock->connected = true;

  } else

    APPL_TRACE_ERROR("send_app_connect_signal failed");

}



static void on_l2cap_connect(tBTA_JV* p_data, uint32_t id) {
@@ -576,7 +578,7 @@ static void on_l2cap_connect(tBTA_JV* p_data, uint32_t id) { 
    return;

  }



  sock->mtu = le_open->tx_mtu;

  sock->tx_mtu = le_open->tx_mtu;

  if (sock->fixed_chan && le_open->status == BTA_JV_SUCCESS) {

    if (!sock->server)

      on_cl_l2cap_le_connect_l(le_open, sock);
@@ -816,9 +818,9 @@ static void btsock_l2cap_server_listen(l2cap_socket* sock) { 
    ertm_info.reset(new tL2CAP_ERTM_INFO(obex_l2c_etm_opt));

  }



  BTA_JvL2capStartServer(

      connection_type, sock->security, 0, std::move(ertm_info), sock->channel,

      L2CAP_MAX_SDU_LENGTH, std::move(cfg), btsock_l2cap_cbk, sock->id);

  BTA_JvL2capStartServer(connection_type, sock->security, 0,

                         std::move(ertm_info), sock->channel, sock->rx_mtu,

                         std::move(cfg), btsock_l2cap_cbk, sock->id);

}



static bt_status_t btsock_l2cap_listen_or_connect(const char* name,
@@ -854,6 +856,7 @@ static bt_status_t btsock_l2cap_listen_or_connect(const char* name, 
  sock->channel = channel;

  sock->app_uid = app_uid;

  sock->is_le_coc = is_le_coc;

  sock->rx_mtu = is_le_coc ? L2CAP_SDU_LENGTH_LE_MAX : L2CAP_SDU_LENGTH_MAX;



  /* "role" is never initialized in rfcomm code */

  if (listen) {
@@ -874,10 +877,9 @@ static bt_status_t btsock_l2cap_listen_or_connect(const char* name, 
        ertm_info.reset(new tL2CAP_ERTM_INFO(obex_l2c_etm_opt));

      }



      BTA_JvL2capConnect(connection_type, sock->security, 0,

                         std::move(ertm_info), channel, L2CAP_MAX_SDU_LENGTH,

                         std::move(cfg), sock->addr, btsock_l2cap_cbk,

                         sock->id);

      BTA_JvL2capConnect(

          connection_type, sock->security, 0, std::move(ertm_info), channel,

          sock->rx_mtu, std::move(cfg), sock->addr, btsock_l2cap_cbk, sock->id);

    }

  }
@@ -970,7 +972,7 @@ void btsock_l2cap_signaled(int fd, int flags, uint32_t user_id) { 
           BluetoothSocket.write(...) guarantees that any packet send to this

           socket is broken into pieces no bigger than MTU bytes (as requested

           by BT spec). */

        size = std::min(size, (int)sock->mtu);

        size = std::min(size, (int)sock->tx_mtu);



        BT_HDR* buffer = malloc_l2cap_buf(size);

        /* The socket is created with SOCK_SEQPACKET, hence we read one message
@@ -978,11 +980,11 @@ void btsock_l2cap_signaled(int fd, int flags, uint32_t user_id) { 
        ssize_t count;

        OSI_NO_INTR(count = recv(fd, get_l2cap_sdu_start_ptr(buffer), size,

                                 MSG_NOSIGNAL | MSG_DONTWAIT | MSG_TRUNC));

        if (count > sock->mtu) {

        if (count > sock->tx_mtu) {

          /* This can't happen thanks to check in BluetoothSocket.java but leave

           * this in case this socket is ever used anywhere else*/

          LOG(ERROR) << "recv more than MTU. Data will be lost: " << count;

          count = sock->mtu;

          count = sock->tx_mtu;

        }



        /* When multiple packets smaller than MTU are flushed to the socket, the

system/stack/include/l2cdefs.h

+7 −5
Original line number Diff line number Diff line
@@ -322,12 +322,14 @@ 
  (L2CAP_PKT_OVERHEAD + L2CAP_EXT_CONTROL_OVERHEAD + L2CAP_SDU_LEN_OVERHEAD + \

   L2CAP_FCS_LEN)



/* To optimize this, it must be a multiple of the L2CAP PDU length AND match

 * the 3DH5 air including the l2cap headers in each packet. To match the latter,

 * the -5 is added.

 * Changed it to  8087 to have same value between BTIF and L2cap layers

/* TODO: This value can probably be optimized per transport, and per L2CAP

 * socket type, but this should not bring any big performance improvements. For

 * LE CoC, it should be biggest multiple of "PDU length" smaller than 0xffff (so

 * depend on controller buffer size), for Classic, making it multiple of PDU

 * length and also of the 3DH5 air including the l2cap headers in each packet.

 */

#define L2CAP_MAX_SDU_LENGTH (8080 + 26 - (L2CAP_MIN_OFFSET + 6))

#define L2CAP_SDU_LENGTH_MAX (8080 + 26 - (L2CAP_MIN_OFFSET + 6))

constexpr uint16_t L2CAP_SDU_LENGTH_LE_MAX = 0xffff;



/* Part of L2CAP_MIN_OFFSET that is not part of L2CAP

*/