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/******************************************************************************
*
* Copyright (C) 2014 Google, Inc.
*
* 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_l2cap_client"
#include "stack/include/l2cap_client.h"
#include <assert.h>
#include <string.h>
#include "btcore/include/bdaddr.h"
#include "osi/include/allocator.h"
#include "osi/include/buffer.h"
#include "osi/include/list.h"
#include "osi/include/log.h"
#include "osi/include/osi.h"
#include "stack/include/l2c_api.h"
struct l2cap_client_t {
l2cap_client_callbacks_t callbacks;
void *context;
uint16_t local_channel_id;
uint16_t remote_mtu;
bool configured_self;
bool configured_peer;
bool is_congested;
list_t *outbound_fragments;
};
static void connect_completed_cb(uint16_t local_channel_id, uint16_t error_code);
static void config_request_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *requested_parameters);
static void config_completed_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *negotiated_parameters);
static void disconnect_request_cb(uint16_t local_channel_id, bool ack_required);
static void disconnect_completed_cb(uint16_t local_channel_id, uint16_t error_code);
static void congestion_cb(uint16_t local_channel_id, bool is_congested);
static void read_ready_cb(uint16_t local_channel_id, BT_HDR *packet);
static void write_completed_cb(uint16_t local_channel_id, uint16_t packets_completed);
static void fragment_packet(l2cap_client_t *client, buffer_t *packet);
static void dispatch_fragments(l2cap_client_t *client);
static l2cap_client_t *find(uint16_t local_channel_id);
// From the Bluetooth Core specification.
static const uint16_t L2CAP_MTU_DEFAULT = 672;
static const uint16_t L2CAP_MTU_MINIMUM = 48;
static const tL2CAP_APPL_INFO l2cap_callbacks = {
.pL2CA_ConnectCfm_Cb = connect_completed_cb,
.pL2CA_ConfigInd_Cb = config_request_cb,
.pL2CA_ConfigCfm_Cb = config_completed_cb,
.pL2CA_DisconnectInd_Cb = disconnect_request_cb,
.pL2CA_DisconnectCfm_Cb = disconnect_completed_cb,
.pL2CA_CongestionStatus_Cb = congestion_cb,
.pL2CA_DataInd_Cb = read_ready_cb,
.pL2CA_TxComplete_Cb = write_completed_cb,
};
static list_t *l2cap_clients; // A list of l2cap_client_t. Container does not own objects.
buffer_t *l2cap_buffer_new(size_t size) {
buffer_t *buf = buffer_new(size + L2CAP_MIN_OFFSET);
buffer_t *slice = NULL;
if (buf)
slice = buffer_new_slice(buf, size);
buffer_free(buf);
return slice;
}
l2cap_client_t *l2cap_client_new(const l2cap_client_callbacks_t *callbacks, void *context) {
assert(callbacks != NULL);
assert(callbacks->connected != NULL);
assert(callbacks->disconnected != NULL);
assert(callbacks->read_ready != NULL);
assert(callbacks->write_ready != NULL);
if (!l2cap_clients) {
l2cap_clients = list_new(NULL);
if (!l2cap_clients) {
LOG_ERROR(LOG_TAG, "%s unable to allocate space for L2CAP client list.", __func__);
return NULL;
}
}
l2cap_client_t *ret = (l2cap_client_t *)osi_calloc(sizeof(l2cap_client_t));
ret->callbacks = *callbacks;
ret->context = context;
ret->remote_mtu = L2CAP_MTU_DEFAULT;
ret->outbound_fragments = list_new(NULL);
if (!ret) {
LOG_ERROR(LOG_TAG, "%s unable to allocate outbound L2CAP fragment list.", __func__);
goto error;
}
list_append(l2cap_clients, ret);
return ret;
error:;
osi_free(ret);
return NULL;
}
void l2cap_client_free(l2cap_client_t *client) {
if (!client)
return;
list_remove(l2cap_clients, client);
l2cap_client_disconnect(client);
list_free(client->outbound_fragments);
osi_free(client);
}
bool l2cap_client_connect(l2cap_client_t *client, const bt_bdaddr_t *remote_bdaddr, uint16_t psm) {
assert(client != NULL);
assert(remote_bdaddr != NULL);
assert(psm != 0);
assert(!bdaddr_is_empty(remote_bdaddr));
assert(client->local_channel_id == 0);
assert(!client->configured_self);
assert(!client->configured_peer);
assert(!L2C_INVALID_PSM(psm));
client->local_channel_id = L2CA_ConnectReq(psm, (uint8_t *)remote_bdaddr);
if (!client->local_channel_id) {
LOG_ERROR(LOG_TAG, "%s unable to create L2CAP connection.", __func__);
return false;
}
L2CA_SetConnectionCallbacks(client->local_channel_id, &l2cap_callbacks);
return true;
}
void l2cap_client_disconnect(l2cap_client_t *client) {
assert(client != NULL);
if (client->local_channel_id && !L2CA_DisconnectReq(client->local_channel_id))
LOG_ERROR(LOG_TAG, "%s unable to send disconnect message for LCID 0x%04x.", __func__, client->local_channel_id);
client->local_channel_id = 0;
client->remote_mtu = L2CAP_MTU_DEFAULT;
client->configured_self = false;
client->configured_peer = false;
client->is_congested = false;
for (const list_node_t *node = list_begin(client->outbound_fragments); node != list_end(client->outbound_fragments); node = list_next(node))
osi_free(list_node(node));
list_clear(client->outbound_fragments);
}
bool l2cap_client_is_connected(const l2cap_client_t *client) {
assert(client != NULL);
return client->local_channel_id != 0 && client->configured_self && client->configured_peer;
}
bool l2cap_client_write(l2cap_client_t *client, buffer_t *packet) {
assert(client != NULL);
assert(packet != NULL);
assert(l2cap_client_is_connected(client));
if (client->is_congested)
return false;
fragment_packet(client, packet);
dispatch_fragments(client);
return true;
}
static void connect_completed_cb(uint16_t local_channel_id, uint16_t error_code) {
assert(local_channel_id != 0);
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client for LCID 0x%04x.", __func__, local_channel_id);
return;
}
if (error_code != L2CAP_CONN_OK) {
LOG_ERROR(LOG_TAG, "%s error connecting L2CAP channel: %d.", __func__, error_code);
client->callbacks.disconnected(client, client->context);
return;
}
// Use default L2CAP parameters.
tL2CAP_CFG_INFO desired_parameters;
memset(&desired_parameters, 0, sizeof(desired_parameters));
if (!L2CA_ConfigReq(local_channel_id, &desired_parameters)) {
LOG_ERROR(LOG_TAG, "%s error sending L2CAP config parameters.", __func__);
client->callbacks.disconnected(client, client->context);
}
}
static void config_request_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *requested_parameters) {
tL2CAP_CFG_INFO response;
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
return;
}
memset(&response, 0, sizeof(response));
response.result = L2CAP_CFG_OK;
if (requested_parameters->mtu_present) {
// Make sure the peer chose an MTU at least as large as the minimum L2CAP MTU defined
// by the Bluetooth Core spec.
if (requested_parameters->mtu < L2CAP_MTU_MINIMUM) {
response.mtu = L2CAP_MTU_MINIMUM;
response.mtu_present = true;
response.result = L2CAP_CFG_UNACCEPTABLE_PARAMS;
} else {
client->remote_mtu = requested_parameters->mtu;
}
}
if (requested_parameters->fcr_present) {
if (requested_parameters->fcr.mode != L2CAP_FCR_BASIC_MODE) {
response.fcr_present = true;
response.fcr = requested_parameters->fcr;
response.fcr.mode = L2CAP_FCR_BASIC_MODE;
response.result = L2CAP_CFG_UNACCEPTABLE_PARAMS;
}
}
if (!L2CA_ConfigRsp(local_channel_id, &response)) {
LOG_ERROR(LOG_TAG, "%s unable to send config response for LCID 0x%04x.", __func__, local_channel_id);
l2cap_client_disconnect(client);
return;
}
// If we've configured both endpoints, let the listener know we've connected.
client->configured_peer = true;
if (l2cap_client_is_connected(client))
client->callbacks.connected(client, client->context);
}
static void config_completed_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *negotiated_parameters) {
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
return;
}
switch (negotiated_parameters->result) {
// We'll get another configuration response later.
case L2CAP_CFG_PENDING:
break;
case L2CAP_CFG_UNACCEPTABLE_PARAMS:
// TODO: see if we can renegotiate parameters instead of dropping the connection.
LOG_WARN(LOG_TAG, "%s dropping L2CAP connection due to unacceptable config parameters.", __func__);
l2cap_client_disconnect(client);
break;
case L2CAP_CFG_OK:
// If we've configured both endpoints, let the listener know we've connected.
client->configured_self = true;
if (l2cap_client_is_connected(client))
client->callbacks.connected(client, client->context);
break;
// Failure, no further parameter negotiation possible.
default:
LOG_WARN(LOG_TAG, "%s L2CAP parameter negotiation failed with error code %d.", __func__, negotiated_parameters->result);
l2cap_client_disconnect(client);
break;
}
}
static void disconnect_request_cb(uint16_t local_channel_id, bool ack_required) {
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client with LCID 0x%04x.", __func__, local_channel_id);
return;
}
if (ack_required)
L2CA_DisconnectRsp(local_channel_id);
// We already sent a disconnect response so this LCID is now invalid.
client->local_channel_id = 0;
l2cap_client_disconnect(client);
client->callbacks.disconnected(client, client->context);
}
static void disconnect_completed_cb(uint16_t local_channel_id, UNUSED_ATTR uint16_t error_code) {
assert(local_channel_id != 0);
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client with LCID 0x%04x.", __func__, local_channel_id);
return;
}
client->local_channel_id = 0;
l2cap_client_disconnect(client);
client->callbacks.disconnected(client, client->context);
}
static void congestion_cb(uint16_t local_channel_id, bool is_congested) {
assert(local_channel_id != 0);
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
return;
}
client->is_congested = is_congested;
if (!is_congested) {
// If we just decongested, dispatch whatever we have left over in our queue.
// Once that's done, if we're still decongested, notify the listener so it
// can start writing again.
dispatch_fragments(client);
if (!client->is_congested)
client->callbacks.write_ready(client, client->context);
}
}
static void read_ready_cb(uint16_t local_channel_id, BT_HDR *packet) {
assert(local_channel_id != 0);
l2cap_client_t *client = find(local_channel_id);
if (!client) {
LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
return;
}
// TODO(sharvil): eliminate copy from BT_HDR.
buffer_t *buffer = buffer_new(packet->len);
memcpy(buffer_ptr(buffer), packet->data + packet->offset, packet->len);
osi_free(packet);
client->callbacks.read_ready(client, buffer, client->context);
buffer_free(buffer);
}
static void write_completed_cb(UNUSED_ATTR uint16_t local_channel_id, UNUSED_ATTR uint16_t packets_completed) {
// Do nothing. We update congestion state based on the congestion callback
// and we've already removed items from outbound_fragments list so we don't
// really care how many packets were successfully dispatched.
}
static void fragment_packet(l2cap_client_t *client, buffer_t *packet) {
assert(client != NULL);
assert(packet != NULL);
// TODO(sharvil): eliminate copy into BT_HDR.
BT_HDR *bt_packet = osi_malloc(buffer_length(packet) + L2CAP_MIN_OFFSET +
sizeof(BT_HDR));
bt_packet->offset = L2CAP_MIN_OFFSET;
bt_packet->len = buffer_length(packet);
memcpy(bt_packet->data + bt_packet->offset, buffer_ptr(packet), buffer_length(packet));
for (;;) {
if (bt_packet->len <= client->remote_mtu) {
if (bt_packet->len > 0)
list_append(client->outbound_fragments, bt_packet);
else
osi_free(bt_packet);
break;
}
BT_HDR *fragment = osi_malloc(client->remote_mtu + L2CAP_MIN_OFFSET +
sizeof(BT_HDR));
fragment->offset = L2CAP_MIN_OFFSET;
fragment->len = client->remote_mtu;
memcpy(fragment->data + fragment->offset, bt_packet->data + bt_packet->offset, client->remote_mtu);
list_append(client->outbound_fragments, fragment);
bt_packet->offset += client->remote_mtu;
bt_packet->len -= client->remote_mtu;
}
}
static void dispatch_fragments(l2cap_client_t *client) {
assert(client != NULL);
assert(!client->is_congested);
while (!list_is_empty(client->outbound_fragments)) {
BT_HDR *packet = (BT_HDR *)list_front(client->outbound_fragments);
list_remove(client->outbound_fragments, packet);
switch (L2CA_DataWrite(client->local_channel_id, packet)) {
case L2CAP_DW_CONGESTED:
client->is_congested = true;
return;
case L2CAP_DW_FAILED:
LOG_ERROR(LOG_TAG, "%s error writing data to L2CAP connection LCID 0x%04x; disconnecting.", __func__, client->local_channel_id);
l2cap_client_disconnect(client);
return;
case L2CAP_DW_SUCCESS:
break;
}
}
}
static l2cap_client_t *find(uint16_t local_channel_id) {
assert(local_channel_id != 0);
for (const list_node_t *node = list_begin(l2cap_clients); node != list_end(l2cap_clients); node = list_next(node)) {
l2cap_client_t *client = (l2cap_client_t *)list_node(node);
if (client->local_channel_id == local_channel_id)
return client;
}
return NULL;
}