btif/src/btif_sock_l2cap.cc

/*
* Copyright (C) 2014 Samsung System LSI
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

#define LOG_TAG "bt_btif_sock"

#include "btif_sock_l2cap.h"

#include <errno.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include <mutex>

#include <hardware/bt_sock.h>

#include "osi/include/allocator.h"
#include "osi/include/log.h"

#include "bt_common.h"
#include "bt_target.h"
#include "bta_api.h"
#include "bta_jv_api.h"
#include "bta_jv_co.h"
#include "btif_common.h"
#include "btif_sock_sdp.h"
#include "btif_sock_thread.h"
#include "btif_sock_util.h"
#include "btif_uid.h"
#include "btif_util.h"
#include "btm_api.h"
#include "btm_int.h"
#include "btu.h"
#include "hcimsgs.h"
#include "l2c_api.h"
#include "l2cdefs.h"
#include "port_api.h"
#include "sdp_api.h"

struct packet {
  struct packet *next, *prev;
  uint32_t len;
  uint8_t* data;
};

typedef struct l2cap_socket {
  struct l2cap_socket* prev;  // link to prev list item
  struct l2cap_socket* next;  // link to next list item
  bt_bdaddr_t addr;           // other side's address
  char name[256];             // user-friendly name of the service
  uint32_t id;                // just a tag to find this struct
  int app_uid;                // The UID of the app who requested this socket
  int handle;                 // handle from lower layers
  unsigned security;          // security flags
  int channel;                // channel (fixed_chan) or PSM (!fixed_chan)
  int our_fd;                 // fd from our side
  int app_fd;                 // fd from app's side

  unsigned bytes_buffered;
  struct packet* first_packet;  // fist packet to be delivered to app
  struct packet* last_packet;   // last packet to be delivered to app

  fixed_queue_t* incoming_que;    // data that came in but has not yet been read
  unsigned fixed_chan : 1;        // fixed channel (or psm?)
  unsigned server : 1;            // is a server? (or connecting?)
  unsigned connected : 1;         // is connected?
  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?
} l2cap_socket;

static bt_status_t btSock_start_l2cap_server_l(l2cap_socket* sock);

static std::mutex state_lock;

l2cap_socket* socks = NULL;
static uid_set_t* uid_set = NULL;
static int pth = -1;

static void btsock_l2cap_cbk(tBTA_JV_EVT event, tBTA_JV* p_data,
                             uint32_t l2cap_socket_id);

/* TODO: Consider to remove this buffer, as we have a buffer in l2cap as well,
 * and we risk
 *       a buffer overflow with this implementation if the socket data is not
 * read from
 *       JAVA for a while. In such a case we should use flow control to tell the
 * sender to
 *       back off.
 *       BUT remember we need to avoid blocking the BTA task execution - hence
 * we cannot
 *       directly write to the socket.
 *       we should be able to change to store the data pointer here, and just
 * wait
 *       confirming the l2cap_ind until we have more space in the buffer. */

/* returns false if none - caller must free "data" memory when done with it */
static char packet_get_head_l(l2cap_socket* sock, uint8_t** data,
                              uint32_t* len) {
  struct packet* p = sock->first_packet;

  if (!p) return false;

  if (data) *data = sock->first_packet->data;
  if (len) *len = sock->first_packet->len;
  sock->first_packet = p->next;
  if (sock->first_packet)
    sock->first_packet->prev = NULL;
  else
    sock->last_packet = NULL;

  if (len) sock->bytes_buffered -= *len;

  osi_free(p);

  return true;
}

static struct packet* packet_alloc(const uint8_t* data, uint32_t len) {
  struct packet* p = (struct packet*)osi_calloc(sizeof(*p));
  uint8_t* buf = (uint8_t*)osi_malloc(len);

  p->data = buf;
  p->len = len;
  memcpy(p->data, data, len);
  return p;
}

/* makes a copy of the data, returns true on success */
static char packet_put_head_l(l2cap_socket* sock, const void* data,
                              uint32_t len) {
  struct packet* p = packet_alloc((const uint8_t*)data, len);

  /*
   * We do not check size limits here since this is used to undo "getting" a
   * packet that the user read incompletely. That is to say the packet was
   * already in the queue. We do check thos elimits in packet_put_tail_l() since
   * that function is used to put new data into the queue.
   */

  if (!p) return false;

  p->prev = NULL;
  p->next = sock->first_packet;
  sock->first_packet = p;
  if (p->next)
    p->next->prev = p;
  else
    sock->last_packet = p;

  sock->bytes_buffered += len;

  return true;
}

/* makes a copy of the data, returns true on success */
static char packet_put_tail_l(l2cap_socket* sock, const void* data,
                              uint32_t len) {
  struct packet* p = packet_alloc((const uint8_t*)data, len);

  if (sock->bytes_buffered >= L2CAP_MAX_RX_BUFFER) {
    LOG_ERROR(LOG_TAG, "packet_put_tail_l: buffer overflow");
    return false;
  }

  if (!p) {
    LOG_ERROR(LOG_TAG, "packet_put_tail_l: unable to allocate packet...");
    return false;
  }

  p->next = NULL;
  p->prev = sock->last_packet;
  sock->last_packet = p;
  if (p->prev)
    p->prev->next = p;
  else
    sock->first_packet = p;

  sock->bytes_buffered += len;

  return true;
}

static inline void bd_copy(uint8_t* dest, uint8_t* src, bool swap) {
  if (swap) {
    for (int i = 0; i < 6; i++) dest[i] = src[5 - i];
  } else {
    memcpy(dest, src, 6);
  }
}

static char is_inited(void) {
  std::unique_lock<std::mutex> lock(state_lock);
  return pth != -1;
}

/* only call with std::mutex taken */
static l2cap_socket* btsock_l2cap_find_by_id_l(uint32_t id) {
  l2cap_socket* sock = socks;

  while (sock && sock->id != id) sock = sock->next;

  return sock;
}

static void btsock_l2cap_free_l(l2cap_socket* sock) {
  uint8_t* buf;
  l2cap_socket* t = socks;

  while (t && t != sock) t = t->next;

  if (!t) /* prever double-frees */
    return;

  if (sock->next) sock->next->prev = sock->prev;

  if (sock->prev)
    sock->prev->next = sock->next;
  else
    socks = sock->next;

  shutdown(sock->our_fd, SHUT_RDWR);
  close(sock->our_fd);
  if (sock->app_fd != -1) {
    close(sock->app_fd);
  } else {
    APPL_TRACE_ERROR("SOCK_LIST: free(id = %d) - NO app_fd!", sock->id);
  }

  while (packet_get_head_l(sock, &buf, NULL)) osi_free(buf);

  // lower-level close() should be idempotent... so let's call it and see...
  if (sock->is_le_coc) {
    // Only call if we are non server connections
    if (sock->handle >= 0 && (sock->server == false)) {
      BTA_JvL2capClose(sock->handle);
    }
    if ((sock->channel >= 0) && (sock->server == true)) {
      BTA_JvFreeChannel(sock->channel, BTA_JV_CONN_TYPE_L2CAP);
    }
  } else {
    // Only call if we are non server connections
    if ((sock->handle >= 0) && (sock->server == false)) {
      if (sock->fixed_chan)
        BTA_JvL2capCloseLE(sock->handle);
      else
        BTA_JvL2capClose(sock->handle);
    }
    if ((sock->channel >= 0) && (sock->server == true)) {
      if (sock->fixed_chan)
        BTA_JvFreeChannel(sock->channel, BTA_JV_CONN_TYPE_L2CAP_LE);
      else
        BTA_JvFreeChannel(sock->channel, BTA_JV_CONN_TYPE_L2CAP);

      if (!sock->fixed_chan) {
        APPL_TRACE_DEBUG("%s stopping L2CAP server channel %d", __func__,
                         sock->channel);
        BTA_JvL2capStopServer(sock->channel, sock->id);
      }
    }
  }

  APPL_TRACE_DEBUG("%s: free(id = %d)", __func__, sock->id);
  osi_free(sock);
}

static l2cap_socket* btsock_l2cap_alloc_l(const char* name,
                                          const bt_bdaddr_t* addr,
                                          char is_server, int flags) {
  unsigned security = 0;
  int fds[2];
  l2cap_socket* sock = (l2cap_socket*)osi_calloc(sizeof(*sock));

  if (flags & BTSOCK_FLAG_ENCRYPT)
    security |= is_server ? BTM_SEC_IN_ENCRYPT : BTM_SEC_OUT_ENCRYPT;
  if (flags & BTSOCK_FLAG_AUTH)
    security |= is_server ? BTM_SEC_IN_AUTHENTICATE : BTM_SEC_OUT_AUTHENTICATE;
  if (flags & BTSOCK_FLAG_AUTH_MITM)
    security |= is_server ? BTM_SEC_IN_MITM : BTM_SEC_OUT_MITM;
  if (flags & BTSOCK_FLAG_AUTH_16_DIGIT)
    security |= BTM_SEC_IN_MIN_16_DIGIT_PIN;

  if (socketpair(AF_LOCAL, SOCK_SEQPACKET, 0, fds)) {
    APPL_TRACE_ERROR("socketpair failed, errno:%d", errno);
    goto fail_sockpair;
  }

  sock->our_fd = fds[0];
  sock->app_fd = fds[1];
  sock->security = security;
  sock->server = is_server;
  sock->connected = false;
  sock->handle = 0;
  sock->server_psm_sent = false;
  sock->app_uid = -1;

  if (name) strncpy(sock->name, name, sizeof(sock->name) - 1);
  if (addr) sock->addr = *addr;

  sock->first_packet = NULL;
  sock->last_packet = NULL;

  sock->next = socks;
  sock->prev = NULL;
  if (socks) socks->prev = sock;
  sock->id = (socks ? socks->id : 0) + 1;
  socks = sock;
  /* paranoia cap on: verify no ID duplicates due to overflow and fix as needed
   */
  while (1) {
    l2cap_socket* t;
    t = socks->next;
    while (t && t->id != sock->id) {
      t = t->next;
    }
    if (!t && sock->id) /* non-zeor handle is unique -> we're done */
      break;
    /* if we're here, we found a duplicate */
    if (!++sock->id) /* no zero IDs allowed */
      sock->id++;
  }
  APPL_TRACE_DEBUG("SOCK_LIST: alloc(id = %d)", sock->id);
  return sock;

fail_sockpair:
  osi_free(sock);
  return NULL;
}

bt_status_t btsock_l2cap_init(int handle, uid_set_t* set) {
  APPL_TRACE_DEBUG("%s handle = %d", __func__);
  std::unique_lock<std::mutex> lock(state_lock);
  pth = handle;
  socks = NULL;
  uid_set = set;
  return BT_STATUS_SUCCESS;
}

bt_status_t btsock_l2cap_cleanup() {
  std::unique_lock<std::mutex> lock(state_lock);
  pth = -1;
  while (socks) btsock_l2cap_free_l(socks);
  return BT_STATUS_SUCCESS;
}

static inline bool send_app_psm_or_chan_l(l2cap_socket* sock) {
  return sock_send_all(sock->our_fd, (const uint8_t*)&sock->channel,
                       sizeof(sock->channel)) == sizeof(sock->channel);
}

static bool send_app_connect_signal(int fd, const bt_bdaddr_t* addr,
                                    int channel, int status, int send_fd,
                                    int 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_tx_packet_size = tx_mtu;
  if (send_fd != -1) {
    if (sock_send_fd(fd, (const uint8_t*)&cs, sizeof(cs), send_fd) ==
        sizeof(cs))
      return true;
    else
      APPL_TRACE_ERROR("sock_send_fd failed, fd:%d, send_fd:%d", fd, send_fd);
  } else if (sock_send_all(fd, (const uint8_t*)&cs, sizeof(cs)) == sizeof(cs)) {
    return true;
  }
  return false;
}

static void on_srv_l2cap_listen_started(tBTA_JV_L2CAP_START* p_start,
                                        uint32_t id) {
  l2cap_socket* sock;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  if (p_start->status != BTA_JV_SUCCESS) {
    APPL_TRACE_ERROR("Error starting l2cap_listen - status: 0x%04x",
                     p_start->status);
    btsock_l2cap_free_l(sock);
    return;
  }

  sock->handle = p_start->handle;
  APPL_TRACE_DEBUG("on_srv_l2cap_listen_started() sock->handle =%d id:%d",
                   sock->handle, sock->id);

  if (sock->server_psm_sent == false) {
    if (!send_app_psm_or_chan_l(sock)) {
      // closed
      APPL_TRACE_DEBUG("send_app_psm() failed, close rs->id:%d", sock->id);
      btsock_l2cap_free_l(sock);
    } else {
      sock->server_psm_sent = true;
    }
  }
}

static void on_cl_l2cap_init(tBTA_JV_L2CAP_CL_INIT* p_init, uint32_t id) {
  l2cap_socket* sock;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  if (p_init->status != BTA_JV_SUCCESS) {
    btsock_l2cap_free_l(sock);
    return;
  }

  sock->handle = p_init->handle;
}

/**
 * Here we allocate a new sock instance to mimic the BluetoothSocket. The socket
 * will be a clone
 * of the sock representing the BluetoothServerSocket.
 * */
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, (const bt_bdaddr_t*)p_open->rem_bda, false, 0);
  accept_rs->connected = true;
  accept_rs->security = sock->security;
  accept_rs->fixed_chan = sock->fixed_chan;
  accept_rs->channel = sock->channel;
  accept_rs->handle = sock->handle;
  accept_rs->app_uid = sock->app_uid;
  sock->handle =
      -1; /* We should no longer associate this handle with the server socket */
  accept_rs->is_le_coc = sock->is_le_coc;

  /* 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;
  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);
    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 =
        -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.
    if (btSock_start_l2cap_server_l(sock) != BT_STATUS_SUCCESS) {
      btsock_l2cap_free_l(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, (const bt_bdaddr_t*)p_open->rem_bda, false, 0);
  if (accept_rs) {
    // swap IDs
    new_listen_id = accept_rs->id;
    accept_rs->id = sock->id;
    sock->id = new_listen_id;

    accept_rs->handle = p_open->handle;
    accept_rs->connected = true;
    accept_rs->security = sock->security;
    accept_rs->fixed_chan = sock->fixed_chan;
    accept_rs->channel = sock->channel;
    accept_rs->app_uid = sock->app_uid;

    // if we do not set a callback, this socket will be dropped */
    *(p_open->p_p_cback) = (void*)btsock_l2cap_cbk;
    *(p_open->p_user_data) = UINT_TO_PTR(accept_rs->id);

    // 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);
    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 = -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) {
  bd_copy(sock->addr.address, p_open->rem_bda, 0);

  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)) {
    // 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,"
        " server:%d",
        sock->id, sock->channel, sock->server);
    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) {
  bd_copy(sock->addr.address, p_open->rem_bda, 0);

  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)) {
    // 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,"
        " server:%d",
        sock->id, sock->channel, sock->server);
    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) {
  l2cap_socket* sock;
  tBTA_JV_L2CAP_OPEN* psm_open = &p_data->l2c_open;
  tBTA_JV_L2CAP_LE_OPEN* le_open = &p_data->l2c_le_open;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) {
    APPL_TRACE_ERROR("on_l2cap_connect on unknown socket");
    return;
  }

  if (sock->fixed_chan && le_open->status == BTA_JV_SUCCESS) {
    if (!sock->server)
      on_cl_l2cap_le_connect_l(le_open, sock);
    else
      on_srv_l2cap_le_connect_l(le_open, sock);
  } else if (!sock->fixed_chan && psm_open->status == BTA_JV_SUCCESS) {
    if (!sock->server)
      on_cl_l2cap_psm_connect_l(psm_open, sock);
    else
      on_srv_l2cap_psm_connect_l(psm_open, sock);
  } else
    btsock_l2cap_free_l(sock);
}

static void on_l2cap_close(tBTA_JV_L2CAP_CLOSE* p_close, uint32_t id) {
  l2cap_socket* sock;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  APPL_TRACE_DEBUG("on_l2cap_close, slot id:%d, fd:%d, %s:%d, server:%d",
                   sock->id, sock->our_fd,
                   sock->fixed_chan ? "fixed_chan" : "PSM", sock->channel,
                   sock->server);
  // TODO: This does not seem to be called...
  // I'm not sure if this will be called for non-server sockets?
  if (!sock->fixed_chan && (sock->server == true)) {
    BTA_JvFreeChannel(sock->channel, BTA_JV_CONN_TYPE_L2CAP);
  }
  btsock_l2cap_free_l(sock);
}

static void on_l2cap_outgoing_congest(tBTA_JV_L2CAP_CONG* p, uint32_t id) {
  l2cap_socket* sock;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  sock->outgoing_congest = p->cong ? 1 : 0;
  // mointer the fd for any outgoing data
  if (!sock->outgoing_congest) {
    APPL_TRACE_DEBUG(
        "on_l2cap_outgoing_congest: adding fd to btsock_thread...");
    btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,
                         sock->id);
  }
}

static void on_l2cap_write_done(void* req_id, uint16_t len, uint32_t id) {
  l2cap_socket* sock;

  if (req_id != NULL) {
    osi_free(req_id);  // free the buffer
  }

  int app_uid = -1;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  app_uid = sock->app_uid;
  if (!sock->outgoing_congest) {
    // monitor the fd for any outgoing data
    APPL_TRACE_DEBUG("on_l2cap_write_done: adding fd to btsock_thread...");
    btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,
                         sock->id);
  }

  uid_set_add_tx(uid_set, app_uid, len);
}

static void on_l2cap_write_fixed_done(void* req_id, uint16_t len, uint32_t id) {
  l2cap_socket* sock;

  if (req_id != NULL) {
    osi_free(req_id);  // free the buffer
  }

  int app_uid = -1;
  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  app_uid = sock->app_uid;
  if (!sock->outgoing_congest) {
    // monitor the fd for any outgoing data
    btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_RD,
                         sock->id);
  }
  uid_set_add_tx(uid_set, app_uid, len);
}

static void on_l2cap_data_ind(tBTA_JV* evt, uint32_t id) {
  l2cap_socket* sock;

  int app_uid = -1;
  uint32_t bytes_read = 0;

  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) return;

  app_uid = sock->app_uid;

  if (sock->fixed_chan) { /* we do these differently */

    tBTA_JV_LE_DATA_IND* p_le_data_ind = &evt->le_data_ind;
    BT_HDR* p_buf = p_le_data_ind->p_buf;
    uint8_t* data = (uint8_t*)(p_buf + 1) + p_buf->offset;

    if (packet_put_tail_l(sock, data, p_buf->len)) {
      bytes_read = p_buf->len;
      btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_WR,
                           sock->id);
    } else {  // connection must be dropped
      APPL_TRACE_DEBUG(
          "on_l2cap_data_ind() unable to push data to socket - closing"
          " fixed channel");
      BTA_JvL2capCloseLE(sock->handle);
      btsock_l2cap_free_l(sock);
    }

  } else {
    uint8_t buffer[L2CAP_MAX_SDU_LENGTH];
    uint32_t count;

    if (BTA_JvL2capReady(sock->handle, &count) == BTA_JV_SUCCESS) {
      if (BTA_JvL2capRead(sock->handle, sock->id, buffer, count) ==
          BTA_JV_SUCCESS) {
        if (packet_put_tail_l(sock, buffer, count)) {
          bytes_read = count;
          btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP,
                               SOCK_THREAD_FD_WR, sock->id);
        } else {  // connection must be dropped
          APPL_TRACE_DEBUG(
              "on_l2cap_data_ind() unable to push data to socket"
              " - closing channel");
          BTA_JvL2capClose(sock->handle);
          btsock_l2cap_free_l(sock);
        }
      }
    }
  }

  uid_set_add_rx(uid_set, app_uid, bytes_read);
}

static void btsock_l2cap_cbk(tBTA_JV_EVT event, tBTA_JV* p_data,
                             uint32_t l2cap_socket_id) {
  switch (event) {
    case BTA_JV_L2CAP_START_EVT:
      on_srv_l2cap_listen_started(&p_data->l2c_start, l2cap_socket_id);
      break;

    case BTA_JV_L2CAP_CL_INIT_EVT:
      on_cl_l2cap_init(&p_data->l2c_cl_init, l2cap_socket_id);
      break;

    case BTA_JV_L2CAP_OPEN_EVT:
      on_l2cap_connect(p_data, l2cap_socket_id);
      BTA_JvSetPmProfile(p_data->l2c_open.handle, BTA_JV_PM_ID_1,
                         BTA_JV_CONN_OPEN);
      break;

    case BTA_JV_L2CAP_CLOSE_EVT:
      APPL_TRACE_DEBUG("BTA_JV_L2CAP_CLOSE_EVT: id: %u", l2cap_socket_id);
      on_l2cap_close(&p_data->l2c_close, l2cap_socket_id);
      break;

    case BTA_JV_L2CAP_DATA_IND_EVT:
      on_l2cap_data_ind(p_data, l2cap_socket_id);
      APPL_TRACE_DEBUG("BTA_JV_L2CAP_DATA_IND_EVT");
      break;

    case BTA_JV_L2CAP_READ_EVT:
      APPL_TRACE_DEBUG("BTA_JV_L2CAP_READ_EVT not used");
      break;

    case BTA_JV_L2CAP_WRITE_EVT:
      APPL_TRACE_DEBUG("BTA_JV_L2CAP_WRITE_EVT: id: %u", l2cap_socket_id);
      on_l2cap_write_done(p_data->l2c_write.p_data, p_data->l2c_write.len,
                          l2cap_socket_id);
      break;

    case BTA_JV_L2CAP_WRITE_FIXED_EVT:
      APPL_TRACE_DEBUG("BTA_JV_L2CAP_WRITE_FIXED_EVT: id: %u", l2cap_socket_id);
      on_l2cap_write_fixed_done(p_data->l2c_write_fixed.p_data,
                                p_data->l2c_write.len, l2cap_socket_id);
      break;

    case BTA_JV_L2CAP_CONG_EVT:
      on_l2cap_outgoing_congest(&p_data->l2c_cong, l2cap_socket_id);
      break;

    default:
      APPL_TRACE_ERROR("unhandled event %d, slot id: %u", event,
                       l2cap_socket_id);
      break;
  }
}

/* L2CAP default options for OBEX socket connections */
const tL2CAP_FCR_OPTS obex_l2c_fcr_opts_def = {
    L2CAP_FCR_ERTM_MODE,               /* Mandatory for OBEX over l2cap */
    OBX_FCR_OPT_TX_WINDOW_SIZE_BR_EDR, /* Tx window size */
    OBX_FCR_OPT_MAX_TX_B4_DISCNT,      /* Maximum transmissions before
                                          disconnecting */
    OBX_FCR_OPT_RETX_TOUT,             /* Retransmission timeout (2 secs) */
    OBX_FCR_OPT_MONITOR_TOUT,          /* Monitor timeout (12 secs) */
    OBX_FCR_OPT_MAX_PDU_SIZE           /* MPS segment size */
};
const tL2CAP_ERTM_INFO obex_l2c_etm_opt = {
    L2CAP_FCR_ERTM_MODE,     /* Mandatory for OBEX over l2cap */
    L2CAP_FCR_CHAN_OPT_ERTM, /* Mandatory for OBEX over l2cap */
    OBX_USER_RX_BUF_SIZE,    OBX_USER_TX_BUF_SIZE,
    OBX_FCR_RX_BUF_SIZE,     OBX_FCR_TX_BUF_SIZE};

/**
 * When using a dynamic PSM, a PSM allocation is requested from
 * btsock_l2cap_listen_or_connect().
 * The PSM allocation event is refeived in the JV-callback - currently located
 * in RFC-code -
 * and this function is called with the newly allocated PSM.
 */
void on_l2cap_psm_assigned(int id, int psm) {
  /* Setup ETM settings:
   *  mtu will be set below */
  std::unique_lock<std::mutex> lock(state_lock);
  l2cap_socket* sock = btsock_l2cap_find_by_id_l(id);
  if (!sock) {
    APPL_TRACE_ERROR("%s: Error: sock is null", __func__);
    return;
  }

  sock->channel = psm;

  if (btSock_start_l2cap_server_l(sock) != BT_STATUS_SUCCESS)
    btsock_l2cap_free_l(sock);
}

static bt_status_t btSock_start_l2cap_server_l(l2cap_socket* sock) {
  tL2CAP_CFG_INFO cfg;
  bt_status_t stat = BT_STATUS_SUCCESS;
  /* Setup ETM settings:
   *  mtu will be set below */
  memset(&cfg, 0, sizeof(tL2CAP_CFG_INFO));

  cfg.fcr_present = true;
  cfg.fcr = obex_l2c_fcr_opts_def;

  if (sock->fixed_chan) {
    if (BTA_JvL2capStartServerLE(sock->security, 0, NULL, sock->channel,
                                 L2CAP_DEFAULT_MTU, NULL, btsock_l2cap_cbk,
                                 sock->id) != BTA_JV_SUCCESS)
      stat = BT_STATUS_FAIL;

  } else {
    /* If we have a channel specified in the request, just start the server,
     * else we request a PSM and start the server after we receive a PSM. */
    if (sock->channel < 0) {
      if (sock->is_le_coc) {
        if (BTA_JvGetChannelId(BTA_JV_CONN_TYPE_L2CAP_LE, sock->id, 0) !=
            BTA_JV_SUCCESS)
          stat = BT_STATUS_FAIL;
      } else {
        if (BTA_JvGetChannelId(BTA_JV_CONN_TYPE_L2CAP, sock->id, 0) !=
            BTA_JV_SUCCESS)
          stat = BT_STATUS_FAIL;
      }
    } else {
      if (sock->is_le_coc) {
        if (BTA_JvL2capStartServer(BTA_JV_CONN_TYPE_L2CAP_LE, sock->security, 0,
                                   NULL, sock->channel, L2CAP_MAX_SDU_LENGTH,
                                   &cfg, btsock_l2cap_cbk,
                                   sock->id) != BTA_JV_SUCCESS)
          stat = BT_STATUS_FAIL;
      } else {
        if (BTA_JvL2capStartServer(BTA_JV_CONN_TYPE_L2CAP, sock->security, 0,
                                   &obex_l2c_etm_opt, sock->channel,
                                   L2CAP_MAX_SDU_LENGTH, &cfg, btsock_l2cap_cbk,
                                   sock->id) != BTA_JV_SUCCESS)
          stat = BT_STATUS_FAIL;
      }
    }
  }
  return stat;
}

static bt_status_t btsock_l2cap_listen_or_connect(const char* name,
                                                  const bt_bdaddr_t* addr,
                                                  int channel, int* sock_fd,
                                                  int flags, char listen,
                                                  int app_uid) {
  bt_status_t stat;
  int fixed_chan = 1;
  l2cap_socket* sock;
  tL2CAP_CFG_INFO cfg;
  bool is_le_coc = false;

  if (!sock_fd) return BT_STATUS_PARM_INVALID;

  if (channel < 0) {
    // We need to auto assign a PSM
    fixed_chan = 0;
  } else {
    fixed_chan = (channel & L2CAP_MASK_FIXED_CHANNEL) != 0;
    is_le_coc = (channel & L2CAP_MASK_LE_COC_CHANNEL) != 0;
    channel &= ~(L2CAP_MASK_FIXED_CHANNEL | L2CAP_MASK_LE_COC_CHANNEL);
  }

  if (!is_inited()) return BT_STATUS_NOT_READY;

  // TODO: This is kind of bad to lock here, but it is needed for the current
  // design.
  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_alloc_l(name, addr, listen, flags);
  if (!sock) {
    return BT_STATUS_NOMEM;
  }

  sock->fixed_chan = fixed_chan;
  sock->channel = channel;
  sock->app_uid = app_uid;
  sock->is_le_coc = is_le_coc;

  stat = BT_STATUS_SUCCESS;

  /* Setup ETM settings:
   *  mtu will be set below */
  memset(&cfg, 0, sizeof(tL2CAP_CFG_INFO));

  cfg.fcr_present = true;
  cfg.fcr = obex_l2c_fcr_opts_def;

  /* "role" is never initialized in rfcomm code */
  if (listen) {
    stat = btSock_start_l2cap_server_l(sock);
  } else {
    if (fixed_chan) {
      if (BTA_JvL2capConnectLE(sock->security, 0, NULL, channel,
                               L2CAP_DEFAULT_MTU, NULL, sock->addr.address,
                               btsock_l2cap_cbk, sock->id) != BTA_JV_SUCCESS)
        stat = BT_STATUS_FAIL;

    } else {
      if (sock->is_le_coc) {
        if (BTA_JvL2capConnect(BTA_JV_CONN_TYPE_L2CAP_LE, sock->security, 0,
                               NULL, channel, L2CAP_MAX_SDU_LENGTH, &cfg,
                               sock->addr.address, btsock_l2cap_cbk,
                               sock->id) != BTA_JV_SUCCESS)
          stat = BT_STATUS_FAIL;
      } else {
        if (BTA_JvL2capConnect(BTA_JV_CONN_TYPE_L2CAP, sock->security, 0,
                               &obex_l2c_etm_opt, channel, L2CAP_MAX_SDU_LENGTH,
                               &cfg, sock->addr.address, btsock_l2cap_cbk,
                               sock->id) != BTA_JV_SUCCESS)
          stat = BT_STATUS_FAIL;
      }
    }
  }

  if (stat == BT_STATUS_SUCCESS) {
    *sock_fd = sock->app_fd;
    /* We pass the FD to JAVA, but since it runs in another process, we need to
     * also close
     * it in native, either straight away, as done when accepting an incoming
     * connection,
     * or when doing cleanup after this socket */
    sock->app_fd =
        -1; /*This leaks the file descriptor. The FD should be closed in
              JAVA but it apparently do not work */
    btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP,
                         SOCK_THREAD_FD_EXCEPTION, sock->id);
  } else {
    btsock_l2cap_free_l(sock);
  }

  return stat;
}

bt_status_t btsock_l2cap_listen(const char* name, int channel, int* sock_fd,
                                int flags, int app_uid) {
  return btsock_l2cap_listen_or_connect(name, NULL, channel, sock_fd, flags, 1,
                                        app_uid);
}

bt_status_t btsock_l2cap_connect(const bt_bdaddr_t* bd_addr, int channel,
                                 int* sock_fd, int flags, int app_uid) {
  return btsock_l2cap_listen_or_connect(NULL, bd_addr, channel, sock_fd, flags,
                                        0, app_uid);
}

/* return true if we have more to send and should wait for user readiness, false
 * else
 * (for example: unrecoverable error or no data)
 */
static bool flush_incoming_que_on_wr_signal_l(l2cap_socket* sock) {
  uint8_t* buf;
  uint32_t len;

  while (packet_get_head_l(sock, &buf, &len)) {
    ssize_t sent;
    OSI_NO_INTR(sent = send(sock->our_fd, buf, len, MSG_DONTWAIT));
    int saved_errno = errno;

    if (sent == (signed)len)
      osi_free(buf);
    else if (sent >= 0) {
      packet_put_head_l(sock, buf + sent, len - sent);
      osi_free(buf);
      if (!sent) /* special case if other end not keeping up */
        return true;
    } else {
      packet_put_head_l(sock, buf, len);
      osi_free(buf);
      return saved_errno == EWOULDBLOCK || saved_errno == EAGAIN;
    }
  }

  return false;
}

void btsock_l2cap_signaled(int fd, int flags, uint32_t user_id) {
  l2cap_socket* sock;
  char drop_it = false;

  /* We use MSG_DONTWAIT when sending data to JAVA, hence it can be accepted to
   * hold the lock. */
  std::unique_lock<std::mutex> lock(state_lock);
  sock = btsock_l2cap_find_by_id_l(user_id);
  if (!sock) return;

  if ((flags & SOCK_THREAD_FD_RD) && !sock->server) {
    // app sending data
    if (sock->connected) {
      int size = 0;

      if (!(flags & SOCK_THREAD_FD_EXCEPTION) ||
          (ioctl(sock->our_fd, FIONREAD, &size) == 0 && size)) {
        uint8_t* buffer = (uint8_t*)osi_malloc(L2CAP_MAX_SDU_LENGTH);
        /* The socket is created with SOCK_SEQPACKET, hence we read one message
         * at the time. The maximum size of a message is allocated to ensure
         * data is not lost. This is okay to do as Android uses virtual memory,
         * hence even if we only use a fraction of the memory it should not
         * block for others to use the memory. As the definition of
         * ioctl(FIONREAD) do not clearly define what value will be returned if
         * multiple messages are written to the socket before any message is
         * read from the socket, we could potentially risk to allocate way more
         * memory than needed. One of the use cases for this socket is obex
         * where multiple 64kbyte messages are typically written to the socket
         * in a tight loop, hence we risk the ioctl will return the total amount
         * of data in the buffer, which could be multiple 64kbyte chunks.
         * UPDATE: As the stack cannot handle 64kbyte buffers, the size is
         * reduced to around 8kbyte - and using malloc for buffer allocation
         * here seems to be wrong
         * UPDATE: Since we are responsible for freeing the buffer in the
         * write_complete_ind, it is OK to use malloc. */
        ssize_t count;
        OSI_NO_INTR(count = recv(fd, buffer, L2CAP_MAX_SDU_LENGTH,
                                 MSG_NOSIGNAL | MSG_DONTWAIT));
        APPL_TRACE_DEBUG(
            "btsock_l2cap_signaled - %d bytes received from socket", count);

        if (sock->fixed_chan) {
          if (BTA_JvL2capWriteFixed(sock->channel, (BD_ADDR*)&sock->addr,
                                    PTR_TO_UINT(buffer), btsock_l2cap_cbk,
                                    buffer, count, user_id) != BTA_JV_SUCCESS) {
            // On fail, free the buffer
            on_l2cap_write_fixed_done(buffer, count, user_id);
          }
        } else {
          if (BTA_JvL2capWrite(sock->handle, PTR_TO_UINT(buffer), buffer, count,
                               user_id) != BTA_JV_SUCCESS) {
            // On fail, free the buffer
            on_l2cap_write_done(buffer, count, user_id);
          }
        }
      }
    } else
      drop_it = true;
  }
  if (flags & SOCK_THREAD_FD_WR) {
    // app is ready to receive more data, tell stack to enable the data flow
    if (flush_incoming_que_on_wr_signal_l(sock) && sock->connected)
      btsock_thread_add_fd(pth, sock->our_fd, BTSOCK_L2CAP, SOCK_THREAD_FD_WR,
                           sock->id);
  }
  if (drop_it || (flags & SOCK_THREAD_FD_EXCEPTION)) {
    int size = 0;
    if (drop_it || ioctl(sock->our_fd, FIONREAD, &size) != 0 || size == 0)
      btsock_l2cap_free_l(sock);
  }
}