/******************************************************************************
 *
 *  Copyright 1999-2012 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 GATT authentication handling functions
 *
 ******************************************************************************/

#include <bluetooth/log.h>
#include <com_android_bluetooth_flags.h>
#include <string.h>

#include "gatt_api.h"
#include "gatt_int.h"
#include "internal_include/bt_target.h"
#include "osi/include/allocator.h"
#include "osi/include/osi.h"
#include "stack/btm/btm_ble_sec.h"
#include "stack/btm/btm_sec.h"
#include "stack/include/bt_hdr.h"
#include "stack/include/bt_types.h"
#include "stack/include/btm_ble_sec_api.h"
#include "stack/include/btm_status.h"
#include "types/raw_address.h"

using namespace bluetooth;

/*******************************************************************************
 *
 * Function         gatt_sign_data
 *
 * Description      This function sign the data for write command.
 *
 * Returns          true if encrypted, otherwise false.
 *
 ******************************************************************************/
static bool gatt_sign_data(tGATT_CLCB* p_clcb) {
  tGATT_VALUE* p_attr = (tGATT_VALUE*)p_clcb->p_attr_buf;
  uint8_t *p_data = NULL, *p;
  uint16_t payload_size = p_clcb->p_tcb->payload_size;
  bool status = false;
  uint8_t* p_signature;

  /* do not need to mark channel securoty activity for data signing */
  gatt_set_sec_act(p_clcb->p_tcb, GATT_SEC_OK);

  p_data = (uint8_t*)osi_malloc(p_attr->len + 3); /* 3 = 2 byte handle + opcode */

  p = p_data;
  UINT8_TO_STREAM(p, GATT_SIGN_CMD_WRITE);
  UINT16_TO_STREAM(p, p_attr->handle);
  ARRAY_TO_STREAM(p, p_attr->value, p_attr->len);

  /* sign data length should be attribulte value length plus 2B handle + 1B op
   * code */
  if ((payload_size - GATT_AUTH_SIGN_LEN - 3) < p_attr->len) {
    p_attr->len = payload_size - GATT_AUTH_SIGN_LEN - 3;
  }

  p_signature = p_attr->value + p_attr->len;
  if (BTM_BleDataSignature(p_clcb->p_tcb->peer_bda, p_data,
                           (uint16_t)(p_attr->len + 3), /* 3 = 2 byte handle + opcode */
                           p_signature)) {
    p_attr->len += BTM_BLE_AUTH_SIGN_LEN;
    gatt_set_ch_state(p_clcb->p_tcb, GATT_CH_OPEN);
    gatt_act_write(p_clcb, GATT_SEC_SIGN_DATA);
  } else {
    gatt_end_operation(p_clcb, GATT_INTERNAL_ERROR, NULL);
  }

  osi_free(p_data);

  return status;
}

/*******************************************************************************
 *
 * Function         gatt_verify_signature
 *
 * Description      This function start to verify the sign data when receiving
 *                  the data from peer device.
 *
 * Returns
 *
 ******************************************************************************/
void gatt_verify_signature(tGATT_TCB& tcb, uint16_t cid, BT_HDR* p_buf) {
  uint16_t cmd_len;
  uint8_t op_code;
  uint8_t *p, *p_orig = (uint8_t*)(p_buf + 1) + p_buf->offset;
  uint32_t counter;

  if (p_buf->len < GATT_AUTH_SIGN_LEN + 4) {
    log::error("Data length {} less than expected {}", p_buf->len, GATT_AUTH_SIGN_LEN + 4);
    return;
  }
  cmd_len = p_buf->len - GATT_AUTH_SIGN_LEN + 4;
  p = p_orig + cmd_len - 4;
  STREAM_TO_UINT32(counter, p);

  if (!BTM_BleVerifySignature(tcb.peer_bda, p_orig, cmd_len, counter, p)) {
    /* if this is a bad signature, assume from attacker, ignore it  */
    log::error("Signature Verification Failed, data ignored");
    return;
  }

  STREAM_TO_UINT8(op_code, p_orig);
  gatt_server_handle_client_req(tcb, cid, op_code, (uint16_t)(p_buf->len - 1), p_orig);
}
/*******************************************************************************
 *
 * Function         gatt_sec_check_complete
 *
 * Description      security check complete and proceed to data sending action.
 *
 * Returns          void.
 *
 ******************************************************************************/
static void gatt_sec_check_complete(bool sec_check_ok, tGATT_CLCB* p_clcb, uint8_t sec_act) {
  if (p_clcb && p_clcb->p_tcb && p_clcb->p_tcb->pending_enc_clcb.empty()) {
    gatt_set_sec_act(p_clcb->p_tcb, GATT_SEC_NONE);
  }

  if (!sec_check_ok) {
    gatt_end_operation(p_clcb, GATT_AUTH_FAIL, NULL);
  } else if (p_clcb->operation == GATTC_OPTYPE_WRITE) {
    gatt_act_write(p_clcb, sec_act);
  } else if (p_clcb->operation == GATTC_OPTYPE_READ) {
    gatt_act_read(p_clcb, p_clcb->counter);
  }
}
/*******************************************************************************
 *
 * Function         gatt_enc_cmpl_cback
 *
 * Description      link encryption complete callback.
 *
 * Returns
 *
 ******************************************************************************/
static void gatt_enc_cmpl_cback(RawAddress bd_addr, tBT_TRANSPORT transport, void* /* p_ref_data */,
                                tBTM_STATUS result) {
  log::verbose("");
  tGATT_TCB* p_tcb = gatt_find_tcb_by_addr(bd_addr, transport);
  if (!p_tcb) {
    log::error("enc callback for unknown bd_addr");
    return;
  }

  if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENC_PENDING) {
    return;
  }

  if (p_tcb->pending_enc_clcb.empty()) {
    log::error("no operation waiting for encrypting");
    return;
  }

  tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
  p_tcb->pending_enc_clcb.pop_front();

  if (p_clcb != NULL) {
    bool status = false;
    if (result == tBTM_STATUS::BTM_SUCCESS) {
      if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENCRYPT_MITM) {
        status = BTM_IsLinkKeyAuthed(bd_addr, transport);
      } else {
        status = true;
      }
    }

    gatt_sec_check_complete(status, p_clcb, p_tcb->sec_act);
  }

  /* start all other pending operation in queue */
  std::deque<tGATT_CLCB*> new_pending_clcbs;
  while (!p_tcb->pending_enc_clcb.empty()) {
    tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
    p_tcb->pending_enc_clcb.pop_front();
    if (p_clcb != NULL && gatt_security_check_start(p_clcb)) {
      new_pending_clcbs.push_back(p_clcb);
    }
  }
  p_tcb->pending_enc_clcb = new_pending_clcbs;
}

/*******************************************************************************
 *
 * Function         gatt_notify_enc_cmpl
 *
 * Description      link encryption complete notification for all encryption
 *                  process initiated outside GATT.
 *
 * Returns
 *
 ******************************************************************************/
void gatt_notify_enc_cmpl(const RawAddress& bd_addr) {
  tGATT_TCB* p_tcb = gatt_find_tcb_by_addr(bd_addr, BT_TRANSPORT_LE);
  if (!p_tcb) {
    log::verbose("notify GATT for encryption completion of unknown device");
    return;
  }

  if (com::android::bluetooth::flags::gatt_client_dynamic_allocation()) {
    for (auto& [i, p_rcb] : gatt_cb.cl_rcb_map) {
      if (p_rcb->app_cb.p_enc_cmpl_cb) {
        (*p_rcb->app_cb.p_enc_cmpl_cb)(p_rcb->gatt_if, bd_addr);
      }
    }
  } else {
    for (uint8_t i = 0; i < GATT_MAX_APPS; i++) {
      if (gatt_cb.cl_rcb[i].in_use && gatt_cb.cl_rcb[i].app_cb.p_enc_cmpl_cb) {
        (*gatt_cb.cl_rcb[i].app_cb.p_enc_cmpl_cb)(gatt_cb.cl_rcb[i].gatt_if, bd_addr);
      }
    }
  }

  if (gatt_get_sec_act(p_tcb) == GATT_SEC_ENC_PENDING) {
    gatt_set_sec_act(p_tcb, GATT_SEC_NONE);

    std::deque<tGATT_CLCB*> new_pending_clcbs;
    while (!p_tcb->pending_enc_clcb.empty()) {
      tGATT_CLCB* p_clcb = p_tcb->pending_enc_clcb.front();
      p_tcb->pending_enc_clcb.pop_front();
      if (p_clcb != NULL && gatt_security_check_start(p_clcb)) {
        new_pending_clcbs.push_back(p_clcb);
      }
    }
    p_tcb->pending_enc_clcb = new_pending_clcbs;
  }
}
/*******************************************************************************
 *
 * Function         gatt_set_sec_act
 *
 * Description      This function set the sec_act in clcb
 *
 * Returns          none
 *
 ******************************************************************************/
void gatt_set_sec_act(tGATT_TCB* p_tcb, tGATT_SEC_ACTION sec_act) {
  if (p_tcb) {
    p_tcb->sec_act = sec_act;
  }
}
/*******************************************************************************
 *
 * Function         gatt_get_sec_act
 *
 * Description      This function get the sec_act in clcb
 *
 * Returns          none
 *
 ******************************************************************************/
tGATT_SEC_ACTION gatt_get_sec_act(tGATT_TCB* p_tcb) {
  tGATT_SEC_ACTION sec_act = GATT_SEC_NONE;
  if (p_tcb) {
    sec_act = p_tcb->sec_act;
  }
  return sec_act;
}
/**
 * This routine determine the security action based on auth_request and current
 * link status. Returns tGATT_SEC_ACTION (security action)
 */
static tGATT_SEC_ACTION gatt_determine_sec_act(tGATT_CLCB* p_clcb) {
  tGATT_SEC_ACTION act = GATT_SEC_OK;
  tGATT_TCB* p_tcb = p_clcb->p_tcb;
  tGATT_AUTH_REQ auth_req = p_clcb->auth_req;
  bool is_link_encrypted = false;
  bool is_link_key_known = false;
  bool is_key_mitm = false;
  uint8_t key_type;
  tBTM_BLE_SEC_REQ_ACT sec_act = BTM_BLE_SEC_REQ_ACT_NONE;

  if (auth_req == GATT_AUTH_REQ_NONE) {
    return act;
  }

  btm_ble_link_sec_check(p_tcb->peer_bda, auth_req, &sec_act);

  /* if a encryption is pending, need to wait */
  if (sec_act == BTM_BLE_SEC_REQ_ACT_DISCARD && auth_req != GATT_AUTH_REQ_NONE) {
    return GATT_SEC_ENC_PENDING;
  }

  is_link_key_known = BTM_IsLinkKeyKnown(p_tcb->peer_bda, p_clcb->p_tcb->transport);
  is_link_encrypted = BTM_IsEncrypted(p_tcb->peer_bda, p_clcb->p_tcb->transport);
  is_key_mitm = BTM_IsLinkKeyAuthed(p_tcb->peer_bda, p_clcb->p_tcb->transport);

  /* first check link key upgrade required or not */
  switch (auth_req) {
    case GATT_AUTH_REQ_MITM:
    case GATT_AUTH_REQ_SIGNED_MITM:
      if (!is_key_mitm) {
        act = GATT_SEC_ENCRYPT_MITM;
      }
      break;

    case GATT_AUTH_REQ_NO_MITM:
    case GATT_AUTH_REQ_SIGNED_NO_MITM:
      if (!is_link_key_known) {
        act = GATT_SEC_ENCRYPT_NO_MITM;
      }
      break;
    default:
      break;
  }

  /* now check link needs to be encrypted or not if the link key upgrade is not
   * required */
  if (act == GATT_SEC_OK) {
    if (p_tcb->transport == BT_TRANSPORT_LE && (p_clcb->operation == GATTC_OPTYPE_WRITE) &&
        (p_clcb->op_subtype == GATT_WRITE_NO_RSP)) {
      /* this is a write command request
         check data signing required or not */
      if (!is_link_encrypted) {
        btm_ble_get_enc_key_type(p_tcb->peer_bda, &key_type);

        if ((key_type & BTM_LE_KEY_LCSRK) && ((auth_req == GATT_AUTH_REQ_SIGNED_NO_MITM) ||
                                              (auth_req == GATT_AUTH_REQ_SIGNED_MITM))) {
          act = GATT_SEC_SIGN_DATA;
        } else {
          act = GATT_SEC_ENCRYPT;
        }
      }
    } else {
      if (!is_link_encrypted) {
        act = GATT_SEC_ENCRYPT;
      }
    }
  }

  return act;
}

/*******************************************************************************
 *
 * Function         gatt_get_link_encrypt_status
 *
 * Description      This routine get the encryption status of the specified link
 *
 *
 * Returns          tGATT_STATUS link encryption status
 *
 ******************************************************************************/
tGATT_STATUS gatt_get_link_encrypt_status(tGATT_TCB& tcb) {
  tGATT_STATUS encrypt_status = GATT_NOT_ENCRYPTED;

  bool encrypted = BTM_IsEncrypted(tcb.peer_bda, tcb.transport);
  bool link_key_known = BTM_IsLinkKeyKnown(tcb.peer_bda, tcb.transport);
  bool link_key_authed = BTM_IsLinkKeyAuthed(tcb.peer_bda, tcb.transport);

  if (encrypted && link_key_known) {
    encrypt_status = GATT_ENCRYPED_NO_MITM;
    if (link_key_authed) {
      encrypt_status = GATT_ENCRYPED_MITM;
    }
  }

  log::verbose("gatt_get_link_encrypt_status status=0x{:x}", encrypt_status);
  return encrypt_status;
}

/*******************************************************************************
 *
 * Function         gatt_convert_sec_action
 *
 * Description      Convert GATT security action enum into equivalent
 *                  BTM BLE security action enum
 *
 * Returns          bool    true - conversation is successful
 *
 ******************************************************************************/
static bool gatt_convert_sec_action(tGATT_SEC_ACTION gatt_sec_act,
                                    tBTM_BLE_SEC_ACT* p_btm_sec_act) {
  bool status = true;
  switch (gatt_sec_act) {
    case GATT_SEC_ENCRYPT:
      *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT;
      break;
    case GATT_SEC_ENCRYPT_NO_MITM:
      *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT_NO_MITM;
      break;
    case GATT_SEC_ENCRYPT_MITM:
      *p_btm_sec_act = BTM_BLE_SEC_ENCRYPT_MITM;
      break;
    default:
      status = false;
      break;
  }

  return status;
}

/** check link security, return true if p_clcb should be added back to queue */
bool gatt_security_check_start(tGATT_CLCB* p_clcb) {
  tGATT_TCB* p_tcb = p_clcb->p_tcb;
  tGATT_SEC_ACTION sec_act_old = gatt_get_sec_act(p_tcb);

  tGATT_SEC_ACTION gatt_sec_act = gatt_determine_sec_act(p_clcb);

  if (sec_act_old == GATT_SEC_NONE) {
    gatt_set_sec_act(p_tcb, gatt_sec_act);
  }

  switch (gatt_sec_act) {
    case GATT_SEC_SIGN_DATA:
      log::verbose("Do data signing");
      gatt_sign_data(p_clcb);
      break;
    case GATT_SEC_ENCRYPT:
    case GATT_SEC_ENCRYPT_NO_MITM:
    case GATT_SEC_ENCRYPT_MITM:
      if (sec_act_old < GATT_SEC_ENCRYPT) {
        log::verbose("Encrypt now or key upgreade first");
        tBTM_BLE_SEC_ACT btm_ble_sec_act;
        gatt_convert_sec_action(gatt_sec_act, &btm_ble_sec_act);
        tBTM_STATUS btm_status = BTM_SetEncryption(p_tcb->peer_bda, p_tcb->transport,
                                                   gatt_enc_cmpl_cback, NULL, btm_ble_sec_act);
        if ((btm_status != tBTM_STATUS::BTM_SUCCESS) &&
            (btm_status != tBTM_STATUS::BTM_CMD_STARTED)) {
          log::error("BTM_SetEncryption failed btm_status={}", btm_status);
          gatt_set_sec_act(p_tcb, GATT_SEC_NONE);
          gatt_set_ch_state(p_tcb, GATT_CH_OPEN);

          gatt_end_operation(p_clcb, GATT_INSUF_ENCRYPTION, NULL);
          return false;
        }
      }
      return true;
    case GATT_SEC_ENC_PENDING:
      /* wait for link encrypotion to finish */
      return true;
    default:
      gatt_sec_check_complete(true, p_clcb, gatt_sec_act);
      break;
  }

  return false;
}