stack/l2cap/l2cap_client.c

   1 /******************************************************************************
   2  *
   3  *  Copyright (C) 2014 Google, Inc.
   4  *
   5  *  Licensed under the Apache License, Version 2.0 (the "License");
   6  *  you may not use this file except in compliance with the License.
   7  *  You may obtain a copy of the License at:
   8  *
   9  *  http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  *  Unless required by applicable law or agreed to in writing, software
  12  *  distributed under the License is distributed on an "AS IS" BASIS,
  13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  *  See the License for the specific language governing permissions and
  15  *  limitations under the License.
  16  *
  17  ******************************************************************************/
  18
  19 #define LOG_TAG "bt_l2cap_client"
  20
  21 #include "stack/include/l2cap_client.h"
  22
  23 #include <assert.h>
  24 #include <string.h>
  25
  26 #include "btcore/include/bdaddr.h"
  27 #include "osi/include/allocator.h"
  28 #include "osi/include/buffer.h"
  29 #include "osi/include/list.h"
  30 #include "osi/include/log.h"
  31 #include "osi/include/osi.h"
  32 #include "stack/include/l2c_api.h"
  33
  34 struct l2cap_client_t {
  35   l2cap_client_callbacks_t callbacks;
  36   void *context;
  37
  38   uint16_t local_channel_id;
  39   uint16_t remote_mtu;
  40   bool configured_self;
  41   bool configured_peer;
  42   bool is_congested;
  43   list_t *outbound_fragments;
  44 };
  45
  46 static void connect_completed_cb(uint16_t local_channel_id, uint16_t error_code);
  47 static void config_request_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *requested_parameters);
  48 static void config_completed_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *negotiated_parameters);
  49 static void disconnect_request_cb(uint16_t local_channel_id, bool ack_required);
  50 static void disconnect_completed_cb(uint16_t local_channel_id, uint16_t error_code);
  51 static void congestion_cb(uint16_t local_channel_id, bool is_congested);
  52 static void read_ready_cb(uint16_t local_channel_id, BT_HDR *packet);
  53 static void write_completed_cb(uint16_t local_channel_id, uint16_t packets_completed);
  54
  55 static void fragment_packet(l2cap_client_t *client, buffer_t *packet);
  56 static void dispatch_fragments(l2cap_client_t *client);
  57 static l2cap_client_t *find(uint16_t local_channel_id);
  58
  59 // From the Bluetooth Core specification.
  60 static const uint16_t L2CAP_MTU_DEFAULT = 672;
  61 static const uint16_t L2CAP_MTU_MINIMUM = 48;
  62
  63 static const tL2CAP_APPL_INFO l2cap_callbacks = {
  64   .pL2CA_ConnectCfm_Cb       = connect_completed_cb,
  65   .pL2CA_ConfigInd_Cb        = config_request_cb,
  66   .pL2CA_ConfigCfm_Cb        = config_completed_cb,
  67   .pL2CA_DisconnectInd_Cb    = disconnect_request_cb,
  68   .pL2CA_DisconnectCfm_Cb    = disconnect_completed_cb,
  69   .pL2CA_CongestionStatus_Cb = congestion_cb,
  70   .pL2CA_DataInd_Cb          = read_ready_cb,
  71   .pL2CA_TxComplete_Cb       = write_completed_cb,
  72 };
  73
  74 static list_t *l2cap_clients;  // A list of l2cap_client_t. Container does not own objects.
  75
  76 buffer_t *l2cap_buffer_new(size_t size) {
  77   buffer_t *buf = buffer_new(size + L2CAP_MIN_OFFSET);
  78   buffer_t *slice = NULL;
  79   if (buf)
  80     slice = buffer_new_slice(buf, size);
  81   buffer_free(buf);
  82   return slice;
  83 }
  84
  85 l2cap_client_t *l2cap_client_new(const l2cap_client_callbacks_t *callbacks, void *context) {
  86   assert(callbacks != NULL);
  87   assert(callbacks->connected != NULL);
  88   assert(callbacks->disconnected != NULL);
  89   assert(callbacks->read_ready != NULL);
  90   assert(callbacks->write_ready != NULL);
  91
  92   if (!l2cap_clients) {
  93     l2cap_clients = list_new(NULL);
  94     if (!l2cap_clients) {
  95       LOG_ERROR(LOG_TAG, "%s unable to allocate space for L2CAP client list.", __func__);
  96       return NULL;
  97     }
  98   }
  99
 100   l2cap_client_t *ret = (l2cap_client_t *)osi_calloc(sizeof(l2cap_client_t));
 101   if (!ret) {
 102     LOG_ERROR(LOG_TAG, "%s unable to allocate L2CAP client.", __func__);
 103     goto error;
 104   }
 105
 106   ret->callbacks = *callbacks;
 107   ret->context = context;
 108
 109   ret->remote_mtu = L2CAP_MTU_DEFAULT;
 110   ret->outbound_fragments = list_new(NULL);
 111   if (!ret) {
 112     LOG_ERROR(LOG_TAG, "%s unable to allocate outbound L2CAP fragment list.", __func__);
 113     goto error;
 114   }
 115
 116   list_append(l2cap_clients, ret);
 117
 118   return ret;
 119
 120 error:;
 121   osi_free(ret);
 122   return NULL;
 123 }
 124
 125 void l2cap_client_free(l2cap_client_t *client) {
 126   if (!client)
 127     return;
 128
 129   list_remove(l2cap_clients, client);
 130   l2cap_client_disconnect(client);
 131   list_free(client->outbound_fragments);
 132   osi_free(client);
 133 }
 134
 135 bool l2cap_client_connect(l2cap_client_t *client, const bt_bdaddr_t *remote_bdaddr, uint16_t psm) {
 136   assert(client != NULL);
 137   assert(remote_bdaddr != NULL);
 138   assert(psm != 0);
 139   assert(!bdaddr_is_empty(remote_bdaddr));
 140   assert(client->local_channel_id == 0);
 141   assert(!client->configured_self);
 142   assert(!client->configured_peer);
 143   assert(!L2C_INVALID_PSM(psm));
 144
 145   client->local_channel_id = L2CA_ConnectReq(psm, (uint8_t *)remote_bdaddr);
 146   if (!client->local_channel_id) {
 147     LOG_ERROR(LOG_TAG, "%s unable to create L2CAP connection.", __func__);
 148     return false;
 149   }
 150
 151   L2CA_SetConnectionCallbacks(client->local_channel_id, &l2cap_callbacks);
 152   return true;
 153 }
 154
 155 void l2cap_client_disconnect(l2cap_client_t *client) {
 156   assert(client != NULL);
 157
 158   if (client->local_channel_id && !L2CA_DisconnectReq(client->local_channel_id))
 159     LOG_ERROR(LOG_TAG, "%s unable to send disconnect message for LCID 0x%04x.", __func__, client->local_channel_id);
 160
 161   client->local_channel_id = 0;
 162   client->remote_mtu = L2CAP_MTU_DEFAULT;
 163   client->configured_self = false;
 164   client->configured_peer = false;
 165   client->is_congested = false;
 166
 167   for (const list_node_t *node = list_begin(client->outbound_fragments); node != list_end(client->outbound_fragments); node = list_next(node))
 168     osi_freebuf(list_node(node));
 169
 170   list_clear(client->outbound_fragments);
 171 }
 172
 173 bool l2cap_client_is_connected(const l2cap_client_t *client) {
 174   assert(client != NULL);
 175
 176   return client->local_channel_id != 0 && client->configured_self && client->configured_peer;
 177 }
 178
 179 bool l2cap_client_write(l2cap_client_t *client, buffer_t *packet) {
 180   assert(client != NULL);
 181   assert(packet != NULL);
 182   assert(l2cap_client_is_connected(client));
 183
 184   if (client->is_congested)
 185     return false;
 186
 187   fragment_packet(client, packet);
 188   dispatch_fragments(client);
 189   return true;
 190 }
 191
 192 static void connect_completed_cb(uint16_t local_channel_id, uint16_t error_code) {
 193   assert(local_channel_id != 0);
 194
 195   l2cap_client_t *client = find(local_channel_id);
 196   if (!client) {
 197     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client for LCID 0x%04x.", __func__, local_channel_id);
 198     return;
 199   }
 200
 201   if (error_code != L2CAP_CONN_OK) {
 202     LOG_ERROR(LOG_TAG, "%s error connecting L2CAP channel: %d.", __func__, error_code);
 203     client->callbacks.disconnected(client, client->context);
 204     return;
 205   }
 206
 207   // Use default L2CAP parameters.
 208   tL2CAP_CFG_INFO desired_parameters = { 0 };
 209   if (!L2CA_ConfigReq(local_channel_id, &desired_parameters)) {
 210     LOG_ERROR(LOG_TAG, "%s error sending L2CAP config parameters.", __func__);
 211     client->callbacks.disconnected(client, client->context);
 212   }
 213 }
 214
 215 static void config_request_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *requested_parameters) {
 216   tL2CAP_CFG_INFO response = { 0 };
 217   l2cap_client_t *client = find(local_channel_id);
 218
 219   if (!client) {
 220     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
 221     return;
 222   }
 223
 224   response.result = L2CAP_CFG_OK;
 225
 226   if (requested_parameters->mtu_present) {
 227     // Make sure the peer chose an MTU at least as large as the minimum L2CAP MTU defined
 228     // by the Bluetooth Core spec.
 229     if (requested_parameters->mtu < L2CAP_MTU_MINIMUM) {
 230       response.mtu = L2CAP_MTU_MINIMUM;
 231       response.mtu_present = true;
 232       response.result = L2CAP_CFG_UNACCEPTABLE_PARAMS;
 233     } else {
 234       client->remote_mtu = requested_parameters->mtu;
 235     }
 236   }
 237
 238   if (requested_parameters->fcr_present) {
 239     if (requested_parameters->fcr.mode != L2CAP_FCR_BASIC_MODE) {
 240       response.fcr_present = true;
 241       response.fcr = requested_parameters->fcr;
 242       response.fcr.mode = L2CAP_FCR_BASIC_MODE;
 243       response.result = L2CAP_CFG_UNACCEPTABLE_PARAMS;
 244     }
 245   }
 246
 247   if (!L2CA_ConfigRsp(local_channel_id, &response)) {
 248     LOG_ERROR(LOG_TAG, "%s unable to send config response for LCID 0x%04x.", __func__, local_channel_id);
 249     l2cap_client_disconnect(client);
 250     return;
 251   }
 252
 253   // If we've configured both endpoints, let the listener know we've connected.
 254   client->configured_peer = true;
 255   if (l2cap_client_is_connected(client))
 256     client->callbacks.connected(client, client->context);
 257 }
 258
 259 static void config_completed_cb(uint16_t local_channel_id, tL2CAP_CFG_INFO *negotiated_parameters) {
 260   l2cap_client_t *client = find(local_channel_id);
 261
 262   if (!client) {
 263     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
 264     return;
 265   }
 266
 267   switch (negotiated_parameters->result) {
 268     // We'll get another configuration response later.
 269     case L2CAP_CFG_PENDING:
 270       break;
 271
 272     case L2CAP_CFG_UNACCEPTABLE_PARAMS:
 273       // TODO: see if we can renegotiate parameters instead of dropping the connection.
 274       LOG_WARN(LOG_TAG, "%s dropping L2CAP connection due to unacceptable config parameters.", __func__);
 275       l2cap_client_disconnect(client);
 276       break;
 277
 278     case L2CAP_CFG_OK:
 279       // If we've configured both endpoints, let the listener know we've connected.
 280       client->configured_self = true;
 281       if (l2cap_client_is_connected(client))
 282         client->callbacks.connected(client, client->context);
 283       break;
 284
 285     // Failure, no further parameter negotiation possible.
 286     default:
 287       LOG_WARN(LOG_TAG, "%s L2CAP parameter negotiation failed with error code %d.", __func__, negotiated_parameters->result);
 288       l2cap_client_disconnect(client);
 289       break;
 290   }
 291 }
 292
 293 static void disconnect_request_cb(uint16_t local_channel_id, bool ack_required) {
 294   l2cap_client_t *client = find(local_channel_id);
 295   if (!client) {
 296     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client with LCID 0x%04x.", __func__, local_channel_id);
 297     return;
 298   }
 299
 300   if (ack_required)
 301     L2CA_DisconnectRsp(local_channel_id);
 302
 303   // We already sent a disconnect response so this LCID is now invalid.
 304   client->local_channel_id = 0;
 305   l2cap_client_disconnect(client);
 306
 307   client->callbacks.disconnected(client, client->context);
 308 }
 309
 310 static void disconnect_completed_cb(uint16_t local_channel_id, UNUSED_ATTR uint16_t error_code) {
 311   assert(local_channel_id != 0);
 312
 313   l2cap_client_t *client = find(local_channel_id);
 314   if (!client) {
 315     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client with LCID 0x%04x.", __func__, local_channel_id);
 316     return;
 317   }
 318
 319   client->local_channel_id = 0;
 320   l2cap_client_disconnect(client);
 321
 322   client->callbacks.disconnected(client, client->context);
 323 }
 324
 325 static void congestion_cb(uint16_t local_channel_id, bool is_congested) {
 326   assert(local_channel_id != 0);
 327
 328   l2cap_client_t *client = find(local_channel_id);
 329   if (!client) {
 330     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
 331     return;
 332   }
 333
 334   client->is_congested = is_congested;
 335
 336   if (!is_congested) {
 337     // If we just decongested, dispatch whatever we have left over in our queue.
 338     // Once that's done, if we're still decongested, notify the listener so it
 339     // can start writing again.
 340     dispatch_fragments(client);
 341     if (!client->is_congested)
 342       client->callbacks.write_ready(client, client->context);
 343   }
 344 }
 345
 346 static void read_ready_cb(uint16_t local_channel_id, BT_HDR *packet) {
 347   assert(local_channel_id != 0);
 348
 349   l2cap_client_t *client = find(local_channel_id);
 350   if (!client) {
 351     LOG_ERROR(LOG_TAG, "%s unable to find L2CAP client matching LCID 0x%04x.", __func__, local_channel_id);
 352     return;
 353   }
 354
 355   // TODO(sharvil): eliminate copy from BT_HDR.
 356   buffer_t *buffer = buffer_new(packet->len);
 357   memcpy(buffer_ptr(buffer), packet->data + packet->offset, packet->len);
 358   osi_freebuf(packet);
 359
 360   client->callbacks.read_ready(client, buffer, client->context);
 361   buffer_free(buffer);
 362 }
 363
 364 static void write_completed_cb(UNUSED_ATTR uint16_t local_channel_id, UNUSED_ATTR uint16_t packets_completed) {
 365   // Do nothing. We update congestion state based on the congestion callback
 366   // and we've already removed items from outbound_fragments list so we don't
 367   // really care how many packets were successfully dispatched.
 368 }
 369
 370 static void fragment_packet(l2cap_client_t *client, buffer_t *packet) {
 371   assert(client != NULL);
 372   assert(packet != NULL);
 373
 374   // TODO(sharvil): eliminate copy into BT_HDR.
 375   BT_HDR *bt_packet = osi_getbuf(buffer_length(packet) + L2CAP_MIN_OFFSET);
 376   bt_packet->offset = L2CAP_MIN_OFFSET;
 377   bt_packet->len = buffer_length(packet);
 378   memcpy(bt_packet->data + bt_packet->offset, buffer_ptr(packet), buffer_length(packet));
 379
 380   for (;;) {
 381     if (bt_packet->len <= client->remote_mtu) {
 382       if (bt_packet->len > 0)
 383         list_append(client->outbound_fragments, bt_packet);
 384       else
 385         osi_freebuf(bt_packet);
 386       break;
 387     }
 388
 389     BT_HDR *fragment = osi_getbuf(client->remote_mtu + L2CAP_MIN_OFFSET);
 390     fragment->offset = L2CAP_MIN_OFFSET;
 391     fragment->len = client->remote_mtu;
 392     memcpy(fragment->data + fragment->offset, bt_packet->data + bt_packet->offset, client->remote_mtu);
 393
 394     list_append(client->outbound_fragments, fragment);
 395
 396     bt_packet->offset += client->remote_mtu;
 397     bt_packet->len -= client->remote_mtu;
 398   }
 399 }
 400
 401 static void dispatch_fragments(l2cap_client_t *client) {
 402   assert(client != NULL);
 403   assert(!client->is_congested);
 404
 405   while (!list_is_empty(client->outbound_fragments)) {
 406     BT_HDR *packet = (BT_HDR *)list_front(client->outbound_fragments);
 407     list_remove(client->outbound_fragments, packet);
 408
 409     switch (L2CA_DataWrite(client->local_channel_id, packet)) {
 410       case L2CAP_DW_CONGESTED:
 411         client->is_congested = true;
 412         return;
 413
 414       case L2CAP_DW_FAILED:
 415         LOG_ERROR(LOG_TAG, "%s error writing data to L2CAP connection LCID 0x%04x; disconnecting.", __func__, client->local_channel_id);
 416         l2cap_client_disconnect(client);
 417         return;
 418
 419       case L2CAP_DW_SUCCESS:
 420         break;
 421     }
 422   }
 423 }
 424
 425 static l2cap_client_t *find(uint16_t local_channel_id) {
 426   assert(local_channel_id != 0);
 427
 428   for (const list_node_t *node = list_begin(l2cap_clients); node != list_end(l2cap_clients); node = list_next(node)) {
 429     l2cap_client_t *client = (l2cap_client_t *)list_node(node);
 430     if (client->local_channel_id == local_channel_id)
 431       return client;
 432   }
 433
 434   return NULL;
 435 }