/******************************************************************************
 *
 *  Copyright (C) 2008-2012 Broadcom Corporation
 *
 *  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.
 *
 ******************************************************************************/

/******************************************************************************
 *
 *  this file contains the GATT server functions
 *
 ******************************************************************************/

#include "bt_target.h"
#include "bt_utils.h"
#include "osi/include/osi.h"

#include <string.h>
#include "gatt_int.h"
#include "l2c_api.h"
#include "l2c_int.h"
#define GATT_MTU_REQ_MIN_LEN 2

using base::StringPrintf;
/*******************************************************************************
 *
 * Function         gatt_sr_enqueue_cmd
 *
 * Description      This function enqueue the request from client which needs a
 *                  application response, and update the transaction ID.
 *
 * Returns          void
 *
 ******************************************************************************/
uint32_t gatt_sr_enqueue_cmd(tGATT_TCB& tcb, uint8_t op_code, uint16_t handle) {
  tGATT_SR_CMD* p_cmd = &tcb.sr_cmd;
  uint32_t trans_id = 0;

  if ((p_cmd->op_code == 0) ||
      (op_code == GATT_HANDLE_VALUE_CONF)) /* no pending request */
  {
    if (op_code == GATT_CMD_WRITE || op_code == GATT_SIGN_CMD_WRITE ||
        op_code == GATT_REQ_MTU || op_code == GATT_HANDLE_VALUE_CONF) {
      trans_id = ++tcb.trans_id;
    } else {
      p_cmd->trans_id = ++tcb.trans_id;
      p_cmd->op_code = op_code;
      p_cmd->handle = handle;
      p_cmd->status = GATT_NOT_FOUND;
      tcb.trans_id %= GATT_TRANS_ID_MAX;
      trans_id = p_cmd->trans_id;
    }
  }

  return trans_id;
}

/*******************************************************************************
 *
 * Function         gatt_sr_cmd_empty
 *
 * Description      This function checks if the server command queue is empty.
 *
 * Returns          true if empty, false if there is pending command.
 *
 ******************************************************************************/
bool gatt_sr_cmd_empty(tGATT_TCB& tcb) { return (tcb.sr_cmd.op_code == 0); }

/*******************************************************************************
 *
 * Function         gatt_dequeue_sr_cmd
 *
 * Description      This function dequeue the request from command queue.
 *
 * Returns          void
 *
 ******************************************************************************/
void gatt_dequeue_sr_cmd(tGATT_TCB& tcb) {
  /* Double check in case any buffers are queued */
  VLOG(1) << "gatt_dequeue_sr_cmd";
  if (tcb.sr_cmd.p_rsp_msg)
    LOG(ERROR) << "free tcb.sr_cmd.p_rsp_msg = " << tcb.sr_cmd.p_rsp_msg;
  osi_free_and_reset((void**)&tcb.sr_cmd.p_rsp_msg);

  while (!fixed_queue_is_empty(tcb.sr_cmd.multi_rsp_q))
    osi_free(fixed_queue_try_dequeue(tcb.sr_cmd.multi_rsp_q));
  fixed_queue_free(tcb.sr_cmd.multi_rsp_q, NULL);
  memset(&tcb.sr_cmd, 0, sizeof(tGATT_SR_CMD));
}

/*******************************************************************************
 *
 * Function         process_read_multi_rsp
 *
 * Description      This function check the read multiple response.
 *
 * Returns          bool    if all replies have been received
 *
 ******************************************************************************/
static bool process_read_multi_rsp(tGATT_SR_CMD* p_cmd, tGATT_STATUS status,
                                   tGATTS_RSP* p_msg, uint16_t mtu) {
  uint16_t ii, total_len, len;
  uint8_t* p;
  bool is_overflow = false;

  VLOG(1) << StringPrintf("%s status=%d mtu=%d", __func__, status, mtu);

  if (p_cmd->multi_rsp_q == NULL)
    p_cmd->multi_rsp_q = fixed_queue_new(SIZE_MAX);

  /* Enqueue the response */
  BT_HDR* p_buf = (BT_HDR*)osi_malloc(sizeof(tGATTS_RSP));
  memcpy((void*)p_buf, (const void*)p_msg, sizeof(tGATTS_RSP));
  fixed_queue_enqueue(p_cmd->multi_rsp_q, p_buf);

  p_cmd->status = status;
  if (status == GATT_SUCCESS) {
    VLOG(1) << "Multi read count=" << fixed_queue_length(p_cmd->multi_rsp_q)
            << " num_hdls=" << p_cmd->multi_req.num_handles;
    /* Wait till we get all the responses */
    if (fixed_queue_length(p_cmd->multi_rsp_q) ==
        p_cmd->multi_req.num_handles) {
      len = sizeof(BT_HDR) + L2CAP_MIN_OFFSET + mtu;
      p_buf = (BT_HDR*)osi_calloc(len);
      p_buf->offset = L2CAP_MIN_OFFSET;
      p = (uint8_t*)(p_buf + 1) + p_buf->offset;

      /* First byte in the response is the opcode */
      *p++ = GATT_RSP_READ_MULTI;
      p_buf->len = 1;

      /* Now walk through the buffers puting the data into the response in order
       */
      list_t* list = NULL;
      const list_node_t* node = NULL;
      if (!fixed_queue_is_empty(p_cmd->multi_rsp_q))
        list = fixed_queue_get_list(p_cmd->multi_rsp_q);
      for (ii = 0; ii < p_cmd->multi_req.num_handles; ii++) {
        tGATTS_RSP* p_rsp = NULL;

        if (list != NULL) {
          if (ii == 0)
            node = list_begin(list);
          else
            node = list_next(node);
          if (node != list_end(list)) p_rsp = (tGATTS_RSP*)list_node(node);
        }

        if (p_rsp != NULL) {
          total_len = (p_buf->len + p_rsp->attr_value.len);

          if (total_len > mtu) {
            /* just send the partial response for the overflow case */
            len = p_rsp->attr_value.len - (total_len - mtu);
            is_overflow = true;
            VLOG(1) << StringPrintf(
                "multi read overflow available len=%d val_len=%d", len,
                p_rsp->attr_value.len);
          } else {
            len = p_rsp->attr_value.len;
          }

          if (p_rsp->attr_value.handle == p_cmd->multi_req.handles[ii]) {
            memcpy(p, p_rsp->attr_value.value, len);
            if (!is_overflow) p += len;
            p_buf->len += len;
          } else {
            p_cmd->status = GATT_NOT_FOUND;
            break;
          }

          if (is_overflow) break;

        } else {
          p_cmd->status = GATT_NOT_FOUND;
          break;
        }

      } /* loop through all handles*/

      /* Sanity check on the buffer length */
      if (p_buf->len == 0) {
        LOG(ERROR) << __func__ << " nothing found!!";
        p_cmd->status = GATT_NOT_FOUND;
        osi_free(p_buf);
        VLOG(1) << __func__ << "osi_free(p_buf)";
      } else if (p_cmd->p_rsp_msg != NULL) {
        osi_free(p_buf);
      } else {
        p_cmd->p_rsp_msg = p_buf;
      }

      return (true);
    }
  } else /* any handle read exception occurs, return error */
  {
    return (true);
  }

  /* If here, still waiting */
  return (false);
}

/*******************************************************************************
 *
 * Function         gatt_sr_process_app_rsp
 *
 * Description      This function checks whether the response message from
 *                  application matches any pending request.
 *
 * Returns          void
 *
 ******************************************************************************/
tGATT_STATUS gatt_sr_process_app_rsp(tGATT_TCB& tcb, tGATT_IF gatt_if,
                                     UNUSED_ATTR uint32_t trans_id,
                                     uint8_t op_code, tGATT_STATUS status,
                                     tGATTS_RSP* p_msg) {
  tGATT_STATUS ret_code = GATT_SUCCESS;

  VLOG(1) << __func__ << " gatt_if=" << +gatt_if;

  gatt_sr_update_cback_cnt(tcb, gatt_if, false, false);

  if (op_code == GATT_REQ_READ_MULTI) {
    /* If no error and still waiting, just return */
    if (!process_read_multi_rsp(&tcb.sr_cmd, status, p_msg, tcb.payload_size))
      return (GATT_SUCCESS);
  } else {
    if (op_code == GATT_REQ_PREPARE_WRITE && status == GATT_SUCCESS)
      gatt_sr_update_prep_cnt(tcb, gatt_if, true, false);

    if (op_code == GATT_REQ_EXEC_WRITE && status != GATT_SUCCESS)
      gatt_sr_reset_cback_cnt(tcb);

    tcb.sr_cmd.status = status;

    if (gatt_sr_is_cback_cnt_zero(tcb) && status == GATT_SUCCESS) {
      if (tcb.sr_cmd.p_rsp_msg == NULL) {
        tcb.sr_cmd.p_rsp_msg = attp_build_sr_msg(tcb, (uint8_t)(op_code + 1),
                                                 (tGATT_SR_MSG*)p_msg);
      } else {
        LOG(ERROR) << "Exception!!! already has respond message";
      }
    }
  }
  if (gatt_sr_is_cback_cnt_zero(tcb)) {
    if ((tcb.sr_cmd.status == GATT_SUCCESS) && (tcb.sr_cmd.p_rsp_msg)) {
      ret_code = attp_send_sr_msg(tcb, tcb.sr_cmd.p_rsp_msg);
      tcb.sr_cmd.p_rsp_msg = NULL;
    } else {
      ret_code =
          gatt_send_error_rsp(tcb, status, op_code, tcb.sr_cmd.handle, false);
    }

    gatt_dequeue_sr_cmd(tcb);
  }

  VLOG(1) << __func__ << " ret_code=" << +ret_code;

  return ret_code;
}

/*******************************************************************************
 *
 * Function         gatt_process_exec_write_req
 *
 * Description      This function is called to process the execute write request
 *                  from client.
 *
 * Returns          void
 *
 ******************************************************************************/
void gatt_process_exec_write_req(tGATT_TCB& tcb, uint8_t op_code,
                                 UNUSED_ATTR uint16_t len, uint8_t* p_data) {
  uint8_t *p = p_data, flag, i = 0;
  uint32_t trans_id = 0;
  tGATT_IF gatt_if;
  uint16_t conn_id;

#if (GATT_CONFORMANCE_TESTING == TRUE)
  if (gatt_cb.enable_err_rsp && gatt_cb.req_op_code == op_code) {
    VLOG(1)
        << "Conformance tst: forced err rspv for Execute Write: error status="
        << +gatt_cb.err_status;

    gatt_send_error_rsp(tcb, gatt_cb.err_status, gatt_cb.req_op_code,
                        gatt_cb.handle, false);

    return;
  }
#endif

  STREAM_TO_UINT8(flag, p);

  /* mask the flag */
  flag &= GATT_PREP_WRITE_EXEC;

  /* no prep write is queued */
  if (!gatt_sr_is_prep_cnt_zero(tcb)) {
    trans_id = gatt_sr_enqueue_cmd(tcb, op_code, 0);
    gatt_sr_copy_prep_cnt_to_cback_cnt(tcb);

    for (i = 0; i < GATT_MAX_APPS; i++) {
      if (tcb.prep_cnt[i]) {
        gatt_if = (tGATT_IF)(i + 1);
        conn_id = GATT_CREATE_CONN_ID(tcb.tcb_idx, gatt_if);
        tGATTS_DATA gatts_data;
        gatts_data.exec_write = flag;
        gatt_sr_send_req_callback(conn_id, trans_id, GATTS_REQ_TYPE_WRITE_EXEC,
                                  &gatts_data);
        tcb.prep_cnt[i] = 0;
      }
    }
  } else /* nothing needs to be executed , send response now */
  {
    LOG(ERROR) << "gatt_process_exec_write_req: no prepare write pending";
    gatt_send_error_rsp(tcb, GATT_ERROR, GATT_REQ_EXEC_WRITE, 0, false);
  }
}

/*******************************************************************************
 *
 * Function         gatt_process_read_multi_req
 *
 * Description      This function is called to process the read multiple request
 *                  from client.
 *
 * Returns          void
 *
 ******************************************************************************/
void gatt_process_read_multi_req(tGATT_TCB& tcb, uint8_t op_code, uint16_t len,
                                 uint8_t* p_data) {
  uint32_t trans_id;
  uint16_t handle = 0, ll = len;
  uint8_t* p = p_data;
  tGATT_STATUS err = GATT_SUCCESS;
  uint8_t sec_flag, key_size;

  VLOG(1) << __func__;
  tcb.sr_cmd.multi_req.num_handles = 0;

  gatt_sr_get_sec_info(tcb.peer_bda, tcb.transport, &sec_flag, &key_size);

#if (GATT_CONFORMANCE_TESTING == TRUE)
  if (gatt_cb.enable_err_rsp && gatt_cb.req_op_code == op_code) {
    VLOG(1) << "Conformance tst: forced err rspvofr ReadMultiple: error status="
            << +gatt_cb.err_status;

    STREAM_TO_UINT16(handle, p);

    gatt_send_error_rsp(tcb, gatt_cb.err_status, gatt_cb.req_op_code, handle,
                        false);

    return;
  }
#endif

  while (ll >= 2 &&
         tcb.sr_cmd.multi_req.num_handles < GATT_MAX_READ_MULTI_HANDLES) {
    STREAM_TO_UINT16(handle, p);

    auto it = gatt_sr_find_i_rcb_by_handle(handle);
    if (it != gatt_cb.srv_list_info->end()) {
      tcb.sr_cmd.multi_req.handles[tcb.sr_cmd.multi_req.num_handles++] = handle;

      /* check read permission */
      err = gatts_read_attr_perm_check(it->p_db, false, handle, sec_flag,
                                       key_size);
      if (err != GATT_SUCCESS) {
        VLOG(1) << StringPrintf("read permission denied : 0x%02x", err);
        break;
      }
    } else {
      /* invalid handle */
      err = GATT_INVALID_HANDLE;
      break;
    }
    ll -= 2;
  }

  if (ll != 0) {
    LOG(ERROR) << "max attribute handle reached in ReadMultiple Request.";
  }

  if (tcb.sr_cmd.multi_req.num_handles == 0) err = GATT_INVALID_HANDLE;

  if (err == GATT_SUCCESS) {
    trans_id =
        gatt_sr_enqueue_cmd(tcb, op_code, tcb.sr_cmd.multi_req.handles[0]);
    if (trans_id != 0) {
      gatt_sr_reset_cback_cnt(tcb); /* read multiple use multi_rsp_q's count*/

      for (ll = 0; ll < tcb.sr_cmd.multi_req.num_handles; ll++) {
        tGATTS_RSP* p_msg = (tGATTS_RSP*)osi_calloc(sizeof(tGATTS_RSP));
        handle = tcb.sr_cmd.multi_req.handles[ll];
        auto it = gatt_sr_find_i_rcb_by_handle(handle);

        p_msg->attr_value.handle = handle;
        err = gatts_read_attr_value_by_handle(
            tcb, it->p_db, op_code, handle, 0, p_msg->attr_value.value,
            &p_msg->attr_value.len, GATT_MAX_ATTR_LEN, sec_flag, key_size,
            trans_id);

        if (err == GATT_SUCCESS) {
          gatt_sr_process_app_rsp(tcb, it->gatt_if, trans_id, op_code,
                                  GATT_SUCCESS, p_msg);
        }
        /* either not using or done using the buffer, release it now */
        osi_free(p_msg);
      }
    } else
      err = GATT_NO_RESOURCES;
  }

  /* in theroy BUSY is not possible(should already been checked), protected
   * check */
  if (err != GATT_SUCCESS && err != GATT_PENDING && err != GATT_BUSY)
    gatt_send_error_rsp(tcb, err, op_code, handle, false);
}

/*******************************************************************************
 *
 * Function         gatt_build_primary_service_rsp
 *
 * Description      Primamry service request processed internally. Theretically
 *                  only deal with ReadByTypeVAlue and ReadByGroupType.
 *
 * Returns          void
 *
 ******************************************************************************/
static tGATT_STATUS gatt_build_primary_service_rsp(
    BT_HDR* p_msg, tGATT_TCB& tcb, uint8_t op_code, uint16_t s_hdl,
    uint16_t e_hdl, UNUSED_ATTR uint8_t* p_data, tBT_UUID value) {
  tGATT_STATUS status = GATT_NOT_FOUND;
  uint8_t handle_len = 4, *p;
  tBT_UUID* p_uuid;

  p = (uint8_t*)(p_msg + 1) + L2CAP_MIN_OFFSET;

  for (tGATT_SRV_LIST_ELEM& el : *gatt_cb.srv_list_info) {
    if (el.s_hdl >= s_hdl && el.s_hdl <= e_hdl &&
        el.type == GATT_UUID_PRI_SERVICE) {
      p_uuid = gatts_get_service_uuid(el.p_db);
      if (p_uuid != NULL) {
        if (op_code == GATT_REQ_READ_BY_GRP_TYPE) handle_len = 4 + p_uuid->len;

        /* get the length byte in the repsonse */
        if (p_msg->offset == 0) {
          *p++ = op_code + 1;
          p_msg->len++;
          p_msg->offset = handle_len;

          if (op_code == GATT_REQ_READ_BY_GRP_TYPE) {
            *p++ = (uint8_t)p_msg->offset; /* length byte */
            p_msg->len++;
          }
        }

        if (p_msg->len + p_msg->offset <= tcb.payload_size &&
            handle_len == p_msg->offset) {
          if (op_code != GATT_REQ_FIND_TYPE_VALUE ||
              gatt_uuid_compare(value, *p_uuid)) {
            UINT16_TO_STREAM(p, el.s_hdl);

            if (gatt_cb.last_primary_s_handle &&
                gatt_cb.last_primary_s_handle == el.s_hdl) {
              VLOG(1) << "Use 0xFFFF for the last primary attribute";
              /* see GATT ERRATA 4065, 4063, ATT ERRATA 4062 */
              UINT16_TO_STREAM(p, 0xFFFF);
            } else {
              UINT16_TO_STREAM(p, el.e_hdl);
            }

            if (op_code == GATT_REQ_READ_BY_GRP_TYPE)
              gatt_build_uuid_to_stream(&p, *p_uuid);

            status = GATT_SUCCESS;
            p_msg->len += p_msg->offset;
          }
        } else
          break;
      }
    }
  }
  p_msg->offset = L2CAP_MIN_OFFSET;

  return status;
}

/**
 * fill the find information response information in the given buffer.
 *
 * Returns          true: if data filled sucessfully.
 *                  false: packet full, or format mismatch.
 */
static tGATT_STATUS gatt_build_find_info_rsp(tGATT_SRV_LIST_ELEM& el,
                                             BT_HDR* p_msg, uint16_t& len,
                                             uint16_t s_hdl, uint16_t e_hdl) {
  uint8_t info_pair_len[2] = {4, 18};

  if (!el.p_db) return GATT_NOT_FOUND;

  /* check the attribute database */

  uint8_t* p = (uint8_t*)(p_msg + 1) + L2CAP_MIN_OFFSET + p_msg->len;

  for (auto& attr : el.p_db->attr_list) {
    if (attr.handle > e_hdl) break;

    if (attr.handle < s_hdl) continue;

    if (p_msg->offset == 0)
      p_msg->offset = (attr.uuid.len == LEN_UUID_16) ? GATT_INFO_TYPE_PAIR_16
                                                     : GATT_INFO_TYPE_PAIR_128;

    if (len < info_pair_len[p_msg->offset - 1]) return GATT_NO_RESOURCES;

    if (p_msg->offset == GATT_INFO_TYPE_PAIR_16 &&
        attr.uuid.len == LEN_UUID_16) {
      UINT16_TO_STREAM(p, attr.handle);
      UINT16_TO_STREAM(p, attr.uuid.uu.uuid16);
    } else if (p_msg->offset == GATT_INFO_TYPE_PAIR_128 &&
               attr.uuid.len == LEN_UUID_128) {
      UINT16_TO_STREAM(p, attr.handle);
      ARRAY_TO_STREAM(p, attr.uuid.uu.uuid128, LEN_UUID_128);
    } else if (p_msg->offset == GATT_INFO_TYPE_PAIR_128 &&
               attr.uuid.len == LEN_UUID_32) {
      UINT16_TO_STREAM(p, attr.handle);
      gatt_convert_uuid32_to_uuid128(p, attr.uuid.uu.uuid32);
      p += LEN_UUID_128;
    } else {
      LOG(ERROR) << "format mismatch";
      return GATT_NO_RESOURCES;
      /* format mismatch */
    }
    p_msg->len += info_pair_len[p_msg->offset - 1];
    len -= info_pair_len[p_msg->offset - 1];
    return GATT_SUCCESS;
  }

  return GATT_NOT_FOUND;
}

static tGATT_STATUS read_handles(uint16_t& len, uint8_t*& p, uint16_t& s_hdl,
                                 uint16_t& e_hdl) {
  if (len < 4) return GATT_INVALID_PDU;

  /* obtain starting handle, and ending handle */
  STREAM_TO_UINT16(s_hdl, p);
  STREAM_TO_UINT16(e_hdl, p);
  len -= 4;

  if (s_hdl > e_hdl || !GATT_HANDLE_IS_VALID(s_hdl) ||
      !GATT_HANDLE_IS_VALID(e_hdl)) {
    return GATT_INVALID_PDU;
  }

  return GATT_SUCCESS;
}

static tGATT_STATUS gatts_validate_packet_format(uint8_t op_code, uint16_t& len,
                                                 uint8_t*& p, tBT_UUID* p_uuid,
                                                 uint16_t& s_hdl,
                                                 uint16_t& e_hdl) {
  tGATT_STATUS ret = read_handles(len, p, s_hdl, e_hdl);
  if (ret != GATT_SUCCESS) return ret;

  if (len < 2) return GATT_INVALID_PDU;

  /* parse uuid now */
  CHECK(p_uuid);
  uint16_t uuid_len = (op_code == GATT_REQ_FIND_TYPE_VALUE) ? 2 : len;
  if (!gatt_parse_uuid_from_cmd(p_uuid, uuid_len, &p)) {
    VLOG(1) << "Bad UUID";
    return GATT_INVALID_PDU;
  }

  len -= uuid_len;
  return GATT_SUCCESS;
}

/*******************************************************************************
 *
 * Function         gatts_process_primary_service_req
 *
 * Description      Process ReadByGroupType/ReadByTypeValue request, for
 *                  discovering all primary services or discover primary service
 *                  by UUID request.
 *
 * Returns          void
 *
 ******************************************************************************/
void gatts_process_primary_service_req(tGATT_TCB& tcb, uint8_t op_code,
                                       uint16_t len, uint8_t* p_data) {
  uint16_t s_hdl = 0, e_hdl = 0;
  tBT_UUID uuid;

  uint8_t reason =
      gatts_validate_packet_format(op_code, len, p_data, &uuid, s_hdl, e_hdl);
  if (reason != GATT_SUCCESS) {
    gatt_send_error_rsp(tcb, reason, op_code, s_hdl, false);
    return;
  }

  tBT_UUID primary_service = {LEN_UUID_16, {GATT_UUID_PRI_SERVICE}};
  if (!gatt_uuid_compare(uuid, primary_service)) {
    if (op_code == GATT_REQ_READ_BY_GRP_TYPE) {
      gatt_send_error_rsp(tcb, GATT_UNSUPPORT_GRP_TYPE, op_code, s_hdl, false);
      VLOG(1) << StringPrintf("unexpected ReadByGrpType Group: 0x%04x",
                              uuid.uu.uuid16);
      return;
    }

    // we do not support ReadByTypeValue with any non-primamry_service type
    gatt_send_error_rsp(tcb, GATT_NOT_FOUND, op_code, s_hdl, false);
    VLOG(1) << StringPrintf("unexpected ReadByTypeValue type: 0x%04x",
                            uuid.uu.uuid16);
    return;
  }

  // TODO: we assume theh value is UUID, there is no such requirement in spec
  tBT_UUID value;
  memset(&value, 0, sizeof(tBT_UUID));
  if (op_code == GATT_REQ_FIND_TYPE_VALUE) {
    if (gatt_parse_uuid_from_cmd(&value, len, &p_data) == false) {
      gatt_send_error_rsp(tcb, GATT_INVALID_PDU, op_code, s_hdl, false);
    }
  }

  uint16_t msg_len =
      (uint16_t)(sizeof(BT_HDR) + tcb.payload_size + L2CAP_MIN_OFFSET);
  BT_HDR* p_msg = (BT_HDR*)osi_calloc(msg_len);
  reason = gatt_build_primary_service_rsp(p_msg, tcb, op_code, s_hdl, e_hdl,
                                          p_data, value);
  if (reason != GATT_SUCCESS) {
    osi_free(p_msg);
    gatt_send_error_rsp(tcb, reason, op_code, s_hdl, false);
    return;
  }

  attp_send_sr_msg(tcb, p_msg);
}

/*******************************************************************************
 *
 * Function         gatts_process_find_info
 *
 * Description      process find information request, for discover character
 *                  descriptors.
 *
 * Returns          void
 *
 ******************************************************************************/
static void gatts_process_find_info(tGATT_TCB& tcb, uint8_t op_code,
                                    uint16_t len, uint8_t* p_data) {
  uint16_t s_hdl = 0, e_hdl = 0;
  uint8_t reason = read_handles(len, p_data, s_hdl, e_hdl);
  if (reason != GATT_SUCCESS) {
    gatt_send_error_rsp(tcb, reason, op_code, s_hdl, false);
    return;
  }

  uint16_t buf_len =
      (uint16_t)(sizeof(BT_HDR) + tcb.payload_size + L2CAP_MIN_OFFSET);

  BT_HDR* p_msg = (BT_HDR*)osi_calloc(buf_len);
  reason = GATT_NOT_FOUND;

  uint8_t* p = (uint8_t*)(p_msg + 1) + L2CAP_MIN_OFFSET;
  *p++ = op_code + 1;
  p_msg->len = 2;

  buf_len = tcb.payload_size - 2;

  for (tGATT_SRV_LIST_ELEM& el : *gatt_cb.srv_list_info) {
    if (el.s_hdl <= e_hdl && el.e_hdl >= s_hdl) {
      reason = gatt_build_find_info_rsp(el, p_msg, buf_len, s_hdl, e_hdl);
      if (reason == GATT_NO_RESOURCES) {
        reason = GATT_SUCCESS;
        break;
      }
    }
  }

  *p = (uint8_t)p_msg->offset;

  p_msg->offset = L2CAP_MIN_OFFSET;

  if (reason != GATT_SUCCESS) {
    osi_free(p_msg);
    gatt_send_error_rsp(tcb, reason, op_code, s_hdl, false);
  } else
    attp_send_sr_msg(tcb, p_msg);
}

/*******************************************************************************
 *
 * Function         gatts_process_mtu_req
 *
 * Description      This function is called to process excahnge MTU request.
 *                  Only used on LE.
 *
 * Returns          void
 *
 ******************************************************************************/
static void gatts_process_mtu_req(tGATT_TCB& tcb, uint16_t len,
                                  uint8_t* p_data) {
  /* BR/EDR conenction, send error response */
  if (tcb.att_lcid != L2CAP_ATT_CID) {
    gatt_send_error_rsp(tcb, GATT_REQ_NOT_SUPPORTED, GATT_REQ_MTU, 0, false);
    return;
  }

  if (len < GATT_MTU_REQ_MIN_LEN) {
    LOG(ERROR) << "invalid MTU request PDU received.";
    gatt_send_error_rsp(tcb, GATT_INVALID_PDU, GATT_REQ_MTU, 0, false);
    return;
  }

  uint16_t mtu = 0;
  uint8_t* p = p_data;
  STREAM_TO_UINT16(mtu, p);
  /* mtu must be greater than default MTU which is 23/48 */
  if (mtu < GATT_DEF_BLE_MTU_SIZE)
    tcb.payload_size = GATT_DEF_BLE_MTU_SIZE;
  else if (mtu > GATT_MAX_MTU_SIZE)
    tcb.payload_size = GATT_MAX_MTU_SIZE;
  else
    tcb.payload_size = mtu;

  LOG(ERROR) << "MTU request PDU with MTU size " << +tcb.payload_size;

  l2cble_set_fixed_channel_tx_data_length(tcb.peer_bda, L2CAP_ATT_CID,
                                          tcb.payload_size);

  tGATT_SR_MSG gatt_sr_msg;
  gatt_sr_msg.mtu = tcb.payload_size;
  BT_HDR* p_buf = attp_build_sr_msg(tcb, GATT_RSP_MTU, &gatt_sr_msg);
  attp_send_sr_msg(tcb, p_buf);

  tGATTS_DATA gatts_data;
  gatts_data.mtu = tcb.payload_size;
  /* Notify all registered applicaiton with new MTU size. Us a transaction ID */
  /* of 0, as no response is allowed from applcations                    */
  for (int i = 0; i < GATT_MAX_APPS; i++) {
    if (gatt_cb.cl_rcb[i].in_use) {
      uint16_t conn_id =
          GATT_CREATE_CONN_ID(tcb.tcb_idx, gatt_cb.cl_rcb[i].gatt_if);
      gatt_sr_send_req_callback(conn_id, 0, GATTS_REQ_TYPE_MTU, &gatts_data);
    }
  }
}

/*******************************************************************************
 *
 * Function         gatts_process_read_by_type_req
 *
 * Description      process Read By type request.
 *                  This PDU can be used to perform:
 *                  - read characteristic value
 *                  - read characteristic descriptor value
 *                  - discover characteristic
 *                  - discover characteristic by UUID
 *                  - relationship discovery
 *
 * Returns          void
 *
 ******************************************************************************/
void gatts_process_read_by_type_req(tGATT_TCB& tcb, uint8_t op_code,
                                    uint16_t len, uint8_t* p_data) {
  tBT_UUID uuid;
  uint16_t s_hdl, e_hdl, err_hdl = 0;
  tGATT_STATUS reason =
      gatts_validate_packet_format(op_code, len, p_data, &uuid, s_hdl, e_hdl);

#if (GATT_CONFORMANCE_TESTING == TRUE)
  if (gatt_cb.enable_err_rsp && gatt_cb.req_op_code == op_code) {
    VLOG(1) << "Conformance tst: forced err rsp for ReadByType: error status="
            << +gatt_cb.err_status;

    gatt_send_error_rsp(tcb, gatt_cb.err_status, gatt_cb.req_op_code, s_hdl,
                        false);

    return;
  }
#endif

  if (reason != GATT_SUCCESS) {
    gatt_send_error_rsp(tcb, reason, op_code, s_hdl, false);
    return;
  }

  size_t msg_len = sizeof(BT_HDR) + tcb.payload_size + L2CAP_MIN_OFFSET;
  BT_HDR* p_msg = (BT_HDR*)osi_calloc(msg_len);
  uint8_t* p = (uint8_t*)(p_msg + 1) + L2CAP_MIN_OFFSET;

  *p++ = op_code + 1;
  /* reserve length byte */
  p_msg->len = 2;
  uint16_t buf_len = tcb.payload_size - 2;

  reason = GATT_NOT_FOUND;
  for (tGATT_SRV_LIST_ELEM& el : *gatt_cb.srv_list_info) {
    if (el.s_hdl <= e_hdl && el.e_hdl >= s_hdl) {
      uint8_t sec_flag, key_size;
      gatt_sr_get_sec_info(tcb.peer_bda, tcb.transport, &sec_flag, &key_size);

      tGATT_STATUS ret = gatts_db_read_attr_value_by_type(
          tcb, el.p_db, op_code, p_msg, s_hdl, e_hdl, uuid, &buf_len, sec_flag,
          key_size, 0, &err_hdl);
      if (ret != GATT_NOT_FOUND) {
        reason = ret;
        if (ret == GATT_NO_RESOURCES) reason = GATT_SUCCESS;
      }

      if (ret != GATT_SUCCESS && ret != GATT_NOT_FOUND) {
        s_hdl = err_hdl;
        break;
      }
    }
  }
  *p = (uint8_t)p_msg->offset;
  p_msg->offset = L2CAP_MIN_OFFSET;

  if (reason != GATT_SUCCESS) {
    osi_free(p_msg);

    /* in theroy BUSY is not possible(should already been checked), protected
     * check */
    if (reason != GATT_PENDING && reason != GATT_BUSY)
      gatt_send_error_rsp(tcb, reason, op_code, s_hdl, false);

    return;
  }

  attp_send_sr_msg(tcb, p_msg);
}

/**
 * This function is called to process the write request from client.
 */
void gatts_process_write_req(tGATT_TCB& tcb, tGATT_SRV_LIST_ELEM& el,
                             uint16_t handle, uint8_t op_code, uint16_t len,
                             uint8_t* p_data,
                             bt_gatt_db_attribute_type_t gatt_type) {
  tGATTS_DATA sr_data;
  uint32_t trans_id;
  tGATT_STATUS status;
  uint8_t sec_flag, key_size, *p = p_data;
  uint16_t conn_id;

  memset(&sr_data, 0, sizeof(tGATTS_DATA));

  switch (op_code) {
    case GATT_REQ_PREPARE_WRITE:
      if (len < 2) {
        LOG(ERROR) << __func__
                   << ": Prepare write request was invalid - missing offset, "
                      "sending error response";
        gatt_send_error_rsp(tcb, GATT_INVALID_PDU, op_code, handle, false);
        return;
      }
      sr_data.write_req.is_prep = true;
      STREAM_TO_UINT16(sr_data.write_req.offset, p);
      len -= 2;
    /* fall through */
    case GATT_SIGN_CMD_WRITE:
      if (op_code == GATT_SIGN_CMD_WRITE) {
        VLOG(1) << "Write CMD with data sigining";
        len -= GATT_AUTH_SIGN_LEN;
      }
    /* fall through */
    case GATT_CMD_WRITE:
    case GATT_REQ_WRITE:
      if (op_code == GATT_REQ_WRITE || op_code == GATT_REQ_PREPARE_WRITE)
        sr_data.write_req.need_rsp = true;
      sr_data.write_req.handle = handle;
      sr_data.write_req.len = len;
      if (len != 0 && p != NULL) {
        memcpy(sr_data.write_req.value, p, len);
      }
      break;
  }

  gatt_sr_get_sec_info(tcb.peer_bda, tcb.transport, &sec_flag, &key_size);

  status = gatts_write_attr_perm_check(el.p_db, op_code, handle,
                                       sr_data.write_req.offset, p, len,
                                       sec_flag, key_size);

  if (status == GATT_SUCCESS) {
    trans_id = gatt_sr_enqueue_cmd(tcb, op_code, handle);
    if (trans_id != 0) {
      conn_id = GATT_CREATE_CONN_ID(tcb.tcb_idx, el.gatt_if);

      uint8_t opcode = 0;
      if (gatt_type == BTGATT_DB_DESCRIPTOR) {
        opcode = GATTS_REQ_TYPE_WRITE_DESCRIPTOR;
      } else if (gatt_type == BTGATT_DB_CHARACTERISTIC) {
        opcode = GATTS_REQ_TYPE_WRITE_CHARACTERISTIC;
      } else {
        LOG(ERROR) << __func__
                   << "%s: Attempt to write attribute that's not tied with"
                      " characteristic or descriptor value.";
        status = GATT_ERROR;
      }

      if (opcode) {
        gatt_sr_send_req_callback(conn_id, trans_id, opcode, &sr_data);
        status = GATT_PENDING;
      }
    } else {
      LOG(ERROR) << "max pending command, send error";
      status = GATT_BUSY; /* max pending command, application error */
    }
  }

  /* in theroy BUSY is not possible(should already been checked), protected
   * check */
  if (status != GATT_PENDING && status != GATT_BUSY &&
      (op_code == GATT_REQ_PREPARE_WRITE || op_code == GATT_REQ_WRITE)) {
    gatt_send_error_rsp(tcb, status, op_code, handle, false);
  }
  return;
}

/**
 * This function is called to process the read request from client.
 */
static void gatts_process_read_req(tGATT_TCB& tcb, tGATT_SRV_LIST_ELEM& el,
                                   uint8_t op_code, uint16_t handle,
                                   UNUSED_ATTR uint16_t len, uint8_t* p_data) {
  size_t buf_len = sizeof(BT_HDR) + tcb.payload_size + L2CAP_MIN_OFFSET;
  uint16_t offset = 0;
  BT_HDR* p_msg = (BT_HDR*)osi_calloc(buf_len);

  if (op_code == GATT_REQ_READ_BLOB) STREAM_TO_UINT16(offset, p_data);

  uint8_t* p = (uint8_t*)(p_msg + 1) + L2CAP_MIN_OFFSET;
  *p++ = op_code + 1;
  p_msg->len = 1;
  buf_len = tcb.payload_size - 1;

  uint8_t sec_flag, key_size;
  gatt_sr_get_sec_info(tcb.peer_bda, tcb.transport, &sec_flag, &key_size);

  uint16_t value_len = 0;
  tGATT_STATUS reason = gatts_read_attr_value_by_handle(
      tcb, el.p_db, op_code, handle, offset, p, &value_len, (uint16_t)buf_len,
      sec_flag, key_size, 0);
  p_msg->len += value_len;

  if (reason != GATT_SUCCESS) {
    osi_free(p_msg);

    /* in theroy BUSY is not possible(should already been checked), protected
     * check */
    if (reason != GATT_PENDING && reason != GATT_BUSY)
      gatt_send_error_rsp(tcb, reason, op_code, handle, false);

    return;
  }

  attp_send_sr_msg(tcb, p_msg);
}

/*******************************************************************************
 *
 * Function         gatts_process_attribute_req
 *
 * Description      This function is called to process the per attribute handle
 *                  request from client.
 *
 * Returns          void
 *
 ******************************************************************************/
void gatts_process_attribute_req(tGATT_TCB& tcb, uint8_t op_code, uint16_t len,
                                 uint8_t* p_data) {
  uint16_t handle = 0;
  uint8_t* p = p_data;
  tGATT_STATUS status = GATT_INVALID_HANDLE;

  if (len < 2) {
    LOG(ERROR) << "Illegal PDU length, discard request";
    status = GATT_INVALID_PDU;
  } else {
    STREAM_TO_UINT16(handle, p);
    len -= 2;
  }

#if (GATT_CONFORMANCE_TESTING == TRUE)
  gatt_cb.handle = handle;
  if (gatt_cb.enable_err_rsp && gatt_cb.req_op_code == op_code) {
    VLOG(1) << "Conformance tst: forced err rsp: error status="
            << +gatt_cb.err_status;

    gatt_send_error_rsp(tcb, gatt_cb.err_status, gatt_cb.req_op_code, handle,
                        false);

    return;
  }
#endif

  if (GATT_HANDLE_IS_VALID(handle)) {
    for (auto& el : *gatt_cb.srv_list_info) {
      if (el.s_hdl <= handle && el.e_hdl >= handle) {
        for (const auto& attr : el.p_db->attr_list) {
          if (attr.handle == handle) {
            switch (op_code) {
              case GATT_REQ_READ: /* read char/char descriptor value */
              case GATT_REQ_READ_BLOB:
                gatts_process_read_req(tcb, el, op_code, handle, len, p);
                break;

              case GATT_REQ_WRITE: /* write char/char descriptor value */
              case GATT_CMD_WRITE:
              case GATT_SIGN_CMD_WRITE:
              case GATT_REQ_PREPARE_WRITE:
                gatts_process_write_req(tcb, el, handle, op_code, len, p,
                                        attr.gatt_type);
                break;
              default:
                break;
            }
            status = GATT_SUCCESS;
            break;
          }
        }
        break;
      }
    }
  }

  if (status != GATT_SUCCESS && op_code != GATT_CMD_WRITE &&
      op_code != GATT_SIGN_CMD_WRITE)
    gatt_send_error_rsp(tcb, status, op_code, handle, false);
}

/*******************************************************************************
 *
 * Function         gatts_proc_srv_chg_ind_ack
 *
 * Description      This function process the service changed indicaiton ACK
 *
 * Returns          void
 *
 ******************************************************************************/
static void gatts_proc_srv_chg_ind_ack(tGATT_TCB tcb) {
  tGATTS_SRV_CHG_REQ req;
  tGATTS_SRV_CHG* p_buf = NULL;

  VLOG(1) << __func__;

  p_buf = gatt_is_bda_in_the_srv_chg_clt_list(tcb.peer_bda);
  if (p_buf != NULL) {
    VLOG(1) << "NV update set srv chg = false";
    p_buf->srv_changed = false;
    memcpy(&req.srv_chg, p_buf, sizeof(tGATTS_SRV_CHG));
    if (gatt_cb.cb_info.p_srv_chg_callback)
      (*gatt_cb.cb_info.p_srv_chg_callback)(GATTS_SRV_CHG_CMD_UPDATE_CLIENT,
                                            &req, NULL);
  }
}

/*******************************************************************************
 *
 * Function         gatts_chk_pending_ind
 *
 * Description      This function check any pending indication needs to be sent
 *                  if there is a pending indication then sent the indication
 *
 * Returns          void
 *
 ******************************************************************************/
static void gatts_chk_pending_ind(tGATT_TCB& tcb) {
  VLOG(1) << __func__;

  tGATT_VALUE* p_buf =
      (tGATT_VALUE*)fixed_queue_try_peek_first(tcb.pending_ind_q);
  if (p_buf != NULL) {
    GATTS_HandleValueIndication(p_buf->conn_id, p_buf->handle, p_buf->len,
                                p_buf->value);
    osi_free(fixed_queue_try_remove_from_queue(tcb.pending_ind_q, p_buf));
  }
}

/*******************************************************************************
 *
 * Function         gatts_proc_ind_ack
 *
 * Description      This function processes the Indication ack
 *
 * Returns          true continue to process the indication ack by the
 *                  application if the ACK is not a Service Changed Indication
 *
 ******************************************************************************/
static bool gatts_proc_ind_ack(tGATT_TCB& tcb, uint16_t ack_handle) {
  bool continue_processing = true;

  VLOG(1) << __func__ << " ack handle=%d" << ack_handle;

  if (ack_handle == gatt_cb.handle_of_h_r) {
    gatts_proc_srv_chg_ind_ack(tcb);
    /* there is no need to inform the application since srv chg is handled
     * internally by GATT */
    continue_processing = false;
  }

  gatts_chk_pending_ind(tcb);
  return continue_processing;
}

/*******************************************************************************
 *
 * Function         gatts_process_value_conf
 *
 * Description      This function is called to process the handle value
 *                  confirmation.
 *
 * Returns          void
 *
 ******************************************************************************/
void gatts_process_value_conf(tGATT_TCB& tcb, uint8_t op_code) {
  uint16_t handle = tcb.indicate_handle;

  alarm_cancel(tcb.conf_timer);
  if (!GATT_HANDLE_IS_VALID(handle)) {
    LOG(ERROR) << "unexpected handle value confirmation";
    return;
  }

  tcb.indicate_handle = 0;
  bool continue_processing = gatts_proc_ind_ack(tcb, handle);

  if (continue_processing) {
    tGATTS_DATA gatts_data;
    gatts_data.handle = handle;
    for (auto& el : *gatt_cb.srv_list_info) {
      if (el.s_hdl <= handle && el.e_hdl >= handle) {
        uint32_t trans_id = gatt_sr_enqueue_cmd(tcb, op_code, handle);
        uint16_t conn_id = GATT_CREATE_CONN_ID(tcb.tcb_idx, el.gatt_if);
        gatt_sr_send_req_callback(conn_id, trans_id, GATTS_REQ_TYPE_CONF,
                                  &gatts_data);
      }
    }
  }
}

/** This function is called to handle the client requests to server */
void gatt_server_handle_client_req(tGATT_TCB& tcb, uint8_t op_code,
                                   uint16_t len, uint8_t* p_data) {
  /* there is pending command, discard this one */
  if (!gatt_sr_cmd_empty(tcb) && op_code != GATT_HANDLE_VALUE_CONF) return;

  /* the size of the message may not be bigger than the local max PDU size*/
  /* The message has to be smaller than the agreed MTU, len does not include op
   * code */
  if (len >= tcb.payload_size) {
    LOG(ERROR) << StringPrintf("server receive invalid PDU size:%d pdu size:%d",
                               len + 1, tcb.payload_size);
    /* for invalid request expecting response, send it now */
    if (op_code != GATT_CMD_WRITE && op_code != GATT_SIGN_CMD_WRITE &&
        op_code != GATT_HANDLE_VALUE_CONF) {
      gatt_send_error_rsp(tcb, GATT_INVALID_PDU, op_code, 0, false);
    }
    /* otherwise, ignore the pkt */
  } else {
    switch (op_code) {
      case GATT_REQ_READ_BY_GRP_TYPE: /* discover primary services */
      case GATT_REQ_FIND_TYPE_VALUE:  /* discover service by UUID */
        gatts_process_primary_service_req(tcb, op_code, len, p_data);
        break;

      case GATT_REQ_FIND_INFO: /* discover char descrptor */
        gatts_process_find_info(tcb, op_code, len, p_data);
        break;

      case GATT_REQ_READ_BY_TYPE: /* read characteristic value, char descriptor
                                     value */
        /* discover characteristic, discover char by UUID */
        gatts_process_read_by_type_req(tcb, op_code, len, p_data);
        break;

      case GATT_REQ_READ: /* read char/char descriptor value */
      case GATT_REQ_READ_BLOB:
      case GATT_REQ_WRITE: /* write char/char descriptor value */
      case GATT_CMD_WRITE:
      case GATT_SIGN_CMD_WRITE:
      case GATT_REQ_PREPARE_WRITE:
        gatts_process_attribute_req(tcb, op_code, len, p_data);
        break;

      case GATT_HANDLE_VALUE_CONF:
        gatts_process_value_conf(tcb, op_code);
        break;

      case GATT_REQ_MTU:
        gatts_process_mtu_req(tcb, len, p_data);
        break;

      case GATT_REQ_EXEC_WRITE:
        gatt_process_exec_write_req(tcb, op_code, len, p_data);
        break;

      case GATT_REQ_READ_MULTI:
        gatt_process_read_multi_req(tcb, op_code, len, p_data);
        break;

      default:
        break;
    }
  }
}