text: // Copyright 2018 Espressif Systems (Shanghai) PTE LTD
  //
  // 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.
  
  #ifndef _TCPIP_ADAPTER_H_
  #define _TCPIP_ADAPTER_H_
  
  /**
   * @brief TCPIP adapter library
   *
   * The aim of this adapter is to provide an abstract layer upon TCPIP stack.
   * With this layer, switch to other TCPIP stack is possible and easy in ESP8266_RTOS_SDK.
   *
   * If users want to use other TCPIP stack, all those functions should be implemented
   * by using the specific APIs of that stack.
   *
   * tcpip_adapter_init should be called in the start of app_main for only once.
   *
   * Currently most adapter APIs are called in event_default_handlers.c.
   *
   * We recommend users only use set/get IP APIs, DHCP server/client APIs,
   * get free station list APIs in application side. Other APIs are used in ESP8266_RTOS_SDK internal,
   * otherwise the state maybe wrong.
   *
   * TODO: ipv6 support will be added, use menuconfig to disable CONFIG_TCPIP_LWIP
   */
  
  #include <stdint.h>
  #include "esp_wifi_types.h"
  
  #define CONFIG_TCPIP_LWIP 1
  #define CONFIG_DHCP_STA_LIST 1
  #define TCPIP_ADAPTER_IPV6 LWIP_IPV6
  
  #if CONFIG_TCPIP_LWIP
  #include "lwip/ip_addr.h"
  #include "dhcpserver/dhcpserver.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #define IP2STR(ipaddr) ip4_addr1_16(ipaddr), \
      ip4_addr2_16(ipaddr), \
      ip4_addr3_16(ipaddr), \
      ip4_addr4_16(ipaddr)
  
  #define IPSTR "%d.%d.%d.%d"
  
  #define IPV62STR(ipaddr) IP6_ADDR_BLOCK1(&(ipaddr)),     \
      IP6_ADDR_BLOCK2(&(ipaddr)),     \
      IP6_ADDR_BLOCK3(&(ipaddr)),     \
      IP6_ADDR_BLOCK4(&(ipaddr)),     \
      IP6_ADDR_BLOCK5(&(ipaddr)),     \
      IP6_ADDR_BLOCK6(&(ipaddr)),     \
      IP6_ADDR_BLOCK7(&(ipaddr)),     \
      IP6_ADDR_BLOCK8(&(ipaddr))
  
  #define IPV6STR "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x"
  
  /**
   *  @brief TCP-IP adapter IPV4 address information
   */
  typedef struct {
      ip4_addr_t ip;              /**< TCP-IP adatpter IPV4 addresss */
      ip4_addr_t netmask;         /**< TCP-IP adatpter IPV4 netmask */
      ip4_addr_t gw;              /**< TCP-IP adatpter IPV4 gateway */
  } tcpip_adapter_ip_info_t;
  
  #if TCPIP_ADAPTER_IPV6
  /**
   *  @brief TCP-IP adapter IPV6 address information if enable IPV6 of LwIP
   */
  typedef struct {
      ip6_addr_t ip;              /**< TCP-IP adatpter IPV6 addresss */
  } tcpip_adapter_ip6_info_t;
  #else
  /**
   *  @brief TCP-IP adapter IPV6 address information if disable IPV6 of LwIP
   */
  typedef struct {
      struct {
          uint32_t addr[4];   /**< TCP-IP adatpter IPV4 addresss data */
      } ip;                   /**< TCP-IP adatpter IPV4 addresss */
  } tcpip_adapter_ip6_info_t;
  #endif
  
  typedef dhcps_lease_t tcpip_adapter_dhcps_lease_t;
  
  #if CONFIG_DHCP_STA_LIST
  /**
   *  @brief TCP-IP adapter station information
   */
  typedef struct {
      uint8_t mac[6];                 /**< TCP-IP adatpter station MAC address */
      ip4_addr_t ip;                  /**< TCP-IP adatpter station IPV4 addresss */
  } tcpip_adapter_sta_info_t;
  
  /**
   *  @brief TCP-IP adapter station information table
   */
  typedef struct {
      tcpip_adapter_sta_info_t sta[ESP_WIFI_MAX_CONN_NUM];    /**< adapter station information array */
      int num;                                                /**< adapter station information number */
  } tcpip_adapter_sta_list_t;
  #endif
  
  #endif
  
  #define ESP_ERR_TCPIP_ADAPTER_BASE      0x5000      // TODO: move base address to esp_err.h
  
  #define ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS        ESP_ERR_TCPIP_ADAPTER_BASE + 0x01
  #define ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY          ESP_ERR_TCPIP_ADAPTER_BASE + 0x02
  #define ESP_ERR_TCPIP_ADAPTER_DHCPC_START_FAILED    ESP_ERR_TCPIP_ADAPTER_BASE + 0x03
  #define ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STARTED  ESP_ERR_TCPIP_ADAPTER_BASE + 0x04
  #define ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STOPPED  ESP_ERR_TCPIP_ADAPTER_BASE + 0x05
  #define ESP_ERR_TCPIP_ADAPTER_NO_MEM                ESP_ERR_TCPIP_ADAPTER_BASE + 0x06
  #define ESP_ERR_TCPIP_ADAPTER_DHCP_NOT_STOPPED      ESP_ERR_TCPIP_ADAPTER_BASE + 0x07
  
  /* @brief On-chip network interfaces */
  typedef enum {
      TCPIP_ADAPTER_IF_STA = 0,     /**< Wi-Fi STA (station) interface */
      TCPIP_ADAPTER_IF_AP,          /**< Wi-Fi soft-AP interface */
      TCPIP_ADAPTER_IF_ETH,         /**< Ethernet interface */
      TCPIP_ADAPTER_IF_TEST,        /**< tcpip stack test interface */
      TCPIP_ADAPTER_IF_MAX
  } tcpip_adapter_if_t;
  
  /*type of DNS server*/
  typedef enum {
      TCPIP_ADAPTER_DNS_MAIN= 0,       /**DNS main server address*/
      TCPIP_ADAPTER_DNS_BACKUP,        /**DNS backup server address,for STA only,support soft-AP in future*/
      TCPIP_ADAPTER_DNS_FALLBACK,      /**DNS fallback server address,for STA only*/
      TCPIP_ADAPTER_DNS_MAX            /**Max DNS */
  } tcpip_adapter_dns_type_t;
  
  /**
   *  @brief TCP-IP adapter DNS server information
   */
  typedef struct {
      ip_addr_t ip;                   /**< DNS IP addresss */
  } tcpip_adapter_dns_info_t;
  
  /* status of DHCP client or DHCP server */
  typedef enum {
      TCPIP_ADAPTER_DHCP_INIT = 0,    /**< DHCP client/server in initial state */
      TCPIP_ADAPTER_DHCP_STARTED,     /**< DHCP client/server already been started */
      TCPIP_ADAPTER_DHCP_STOPPED,     /**< DHCP client/server already been stopped */
      TCPIP_ADAPTER_DHCP_STATUS_MAX
  } tcpip_adapter_dhcp_status_t;
  
  /* set the option mode for DHCP client or DHCP server */
  typedef enum{
      TCPIP_ADAPTER_OP_START = 0,
      TCPIP_ADAPTER_OP_SET,           /**< set option mode */
      TCPIP_ADAPTER_OP_GET,           /**< get option mode */
      TCPIP_ADAPTER_OP_MAX
  } tcpip_adapter_option_mode_t;
  
  typedef enum{
      TCPIP_ADAPTER_DOMAIN_NAME_SERVER            = 6,    /**< domain name server */
      TCPIP_ADAPTER_ROUTER_SOLICITATION_ADDRESS   = 32,   /**< solicitation router address */
      TCPIP_ADAPTER_REQUESTED_IP_ADDRESS          = 50,   /**< request IP address pool */
      TCPIP_ADAPTER_IP_ADDRESS_LEASE_TIME         = 51,   /**< request IP address lease time */
      TCPIP_ADAPTER_IP_REQUEST_RETRY_TIME         = 52,   /**< request IP address retry counter */
  } tcpip_adapter_option_id_t;
  
  /** @brief IP event base declaration */
  ESP_EVENT_DECLARE_BASE(IP_EVENT);
  
  /** IP event declarations */
  typedef enum {
      IP_EVENT_STA_GOT_IP,               /*!< station got IP from connected AP */
      IP_EVENT_STA_LOST_IP,              /*!< station lost IP and the IP is reset to 0 */
      IP_EVENT_AP_STAIPASSIGNED,         /*!< soft-AP assign an IP to a connected station */
      IP_EVENT_GOT_IP6,                  /*!< station or ap or ethernet interface v6IP addr is preferred */
  } ip_event_t;
  
  /** Event structure for IP_EVENT_AP_STAIPASSIGNED event */
  typedef struct {
      ip4_addr_t ip; /*!< IP address which was assigned to the station */
  } ip_event_ap_staipassigned_t;
  
  /** Event structure for IP_EVENT_STA_GOT_IP, IP_EVENT_ETH_GOT_IP events  */
  typedef struct {
      tcpip_adapter_if_t if_index;        /*!< Interface for which the event is received */
      tcpip_adapter_ip_info_t ip_info;    /*!< IP address, netmask, gatway IP address */
      bool ip_changed;                    /*!< Whether the assigned IP has changed or not */
  } ip_event_got_ip_t;
  
  /** Event structure for IP_EVENT_GOT_IP6 event */
  typedef struct {
      tcpip_adapter_if_t if_index;        /*!< Interface for which the event is received */
      tcpip_adapter_ip6_info_t ip6_info;  /*!< IPv6 address of the interface */
  } ip_event_got_ip6_t;
  
  struct tcpip_adapter_api_msg_s;
  typedef int (*tcpip_adapter_api_fn)(struct tcpip_adapter_api_msg_s *msg);
  
  /**
   *  @brief TCP-IP adapter async messsage
   */
  typedef struct tcpip_adapter_api_msg_s {
      int type;                               /**< TCP-IP adatpter API message type */
      int ret;                                /**< TCP-IP adatpter API message process result */
      tcpip_adapter_api_fn api_fn;            /**< TCP-IP adatpter API message function */
      tcpip_adapter_if_t tcpip_if;            /**< TCP-IP adatpter API message interface type */
      tcpip_adapter_ip_info_t *ip_info;       /**< TCP-IP adatpter API message IP information */
      uint8_t *mac;                           /**< TCP-IP adatpter API message MAC address */
      void    *data;                          /**< TCP-IP adatpter API message MAC private data */
  } tcpip_adapter_api_msg_t;
  
  /**
   *  @brief TCP-IP adapter DNS parameters
   */
  typedef struct tcpip_adapter_dns_param_s {
      tcpip_adapter_dns_type_t dns_type;      /**< DNS type */
      tcpip_adapter_dns_info_t *dns_info;     /**< DNS information */
  } tcpip_adapter_dns_param_t;
  
  #define TCPIP_ADAPTER_TRHEAD_SAFE 1
  #define TCPIP_ADAPTER_IPC_LOCAL   0 
  #define TCPIP_ADAPTER_IPC_REMOTE  1
  
  /**
   *  @brief TCP-IP adapter IP lost checking timer
   */
  typedef struct tcpip_adatper_ip_lost_timer_s {
      bool timer_running;         /**< check if the timer if running */
  } tcpip_adapter_ip_lost_timer_t;
  
  /**
   * @brief  Initialize tcpip adapter
   *
   * This will initialize TCPIP stack inside.
   */
  void tcpip_adapter_init(void);
  
  /**
   * @brief  Start the Wi-Fi station/AP interface with specific MAC and IP
   *
   * Station/AP interface will be initialized, connect WiFi stack with TCPIP stack.
   *
   * @param[in]  tcpip_if: Station/AP interface
   * @param[in]  mac: set MAC address of this interface
   * @param[in]  ip_info: set IP address of this interface
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_NO_MEM
   */
  esp_err_t tcpip_adapter_start(tcpip_adapter_if_t tcpip_if, uint8_t *mac, tcpip_adapter_ip_info_t *ip_info);
  
  /**
   * @brief  Stop an interface
   *
   * The interface will be cleanup in this API, if DHCP server/client are started, will be stopped.
   *
   * @param[in]  tcpip_if: the interface which will be started
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY
   */
  esp_err_t tcpip_adapter_stop(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Bring up an interface
   *
   * Only station interface need to be brought up, since station interface will be shut down when disconnect.
   *
   * @param[in]  tcpip_if: the interface which will be up
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY
   */
  esp_err_t tcpip_adapter_up(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Shut down an interface
   *
   * Only station interface need to be shut down, since station interface will be brought up when connect.
   *
   * @param[in]  tcpip_if: the interface which will be down
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY
   */
  esp_err_t tcpip_adapter_down(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Get interface's IP information
   *
   * There has an IP information copy in adapter library, if interface is up, get IP information from
   * interface, otherwise get from copy.
   *
   * @param[in]   tcpip_if: the interface which we want to get IP information
   * @param[out]  ip_info: If successful, IP information will be returned in this argument.
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_get_ip_info(tcpip_adapter_if_t tcpip_if, tcpip_adapter_ip_info_t *ip_info);
  
  /**
   * @brief  Set interface's IP information
   *
   * There has an IP information copy in adapter library, if interface is up, also set interface's IP.
   * DHCP client/server should be stopped before set new IP information.
   *
   * This function is mainly used for setting static IP.
   *
   * @param[in]  tcpip_if: the interface which we want to set IP information
   * @param[in]  ip_info: store the IP information which needs to be set to specified interface
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_set_ip_info(tcpip_adapter_if_t tcpip_if, tcpip_adapter_ip_info_t *ip_info);
  
  /**
   * @brief  Set DNS Server's information
   *
   * There has an DNS Server information copy in adapter library, set DNS Server for appointed interface and type.
   *
   * 1.In station mode, if dhcp client is enabled, then only the fallback DNS server can be set(TCPIP_ADAPTER_DNS_FALLBACK).
   *   Fallback DNS server is only used if no DNS servers are set via DHCP.
   *   If dhcp client is disabled, then need to set main/backup dns server(TCPIP_ADAPTER_DNS_MAIN, TCPIP_ADAPTER_DNS_BACKUP).
   * 
   * 2.In soft-AP mode, the DNS Server's main dns server offered to the station is the IP address of soft-AP, 
   *   if the application don't want to use the IP address of soft-AP, they can set the main dns server.
   *
   * This function is mainly used for setting static or Fallback DNS Server.
   *
   * @param[in]  tcpip_if: the interface which we want to set DNS Server information
   * @param[in]  type: the type of DNS Server,including TCPIP_ADAPTER_DNS_MAIN, TCPIP_ADAPTER_DNS_BACKUP, TCPIP_ADAPTER_DNS_FALLBACK
   * @param[in]  dns:  the DNS Server address to be set
   * 
   * @return 
   *      - ESP_OK on success
   *      - ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS invalid params
   */
  esp_err_t tcpip_adapter_set_dns_info(tcpip_adapter_if_t tcpip_if, tcpip_adapter_dns_type_t type, tcpip_adapter_dns_info_t *dns);
  
  /**
   * @brief  Get DNS Server's information
   *
   * When set the DNS Server information successfully, can get the DNS Server's information via the appointed tcpip_if and type 
   *
   * This function is mainly used for getting DNS Server information.
   *
   * @param[in]  tcpip_if: the interface which we want to get DNS Server information
   * @param[in]  type: the type of DNS Server,including TCPIP_ADAPTER_DNS_MAIN, TCPIP_ADAPTER_DNS_BACKUP, TCPIP_ADAPTER_DNS_FALLBACK
   * @param[in]  dns:  the DNS Server address to be get
   * 
   * @return 
   *      - ESP_OK on success
   *      - ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS invalid params
   */
  esp_err_t tcpip_adapter_get_dns_info(tcpip_adapter_if_t tcpip_if, tcpip_adapter_dns_type_t type, tcpip_adapter_dns_info_t *dns);
  
  /**
   * @brief  Get interface's old IP information
   *
   * When the interface successfully gets a valid IP from DHCP server or static configured, a copy of 
   * the IP information is set to the old IP information. When IP lost timer expires, the old IP 
   * information is reset to 0.
   *
   * @param[in]   tcpip_if: the interface which we want to get old IP information
   * @param[out]  ip_info: If successful, IP information will be returned in this argument.
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_get_old_ip_info(tcpip_adapter_if_t tcpip_if, tcpip_adapter_ip_info_t *ip_info);
  
  /**
   * @brief  Set interface's old IP information
   *
   * When the interface successfully gets a valid IP from DHCP server or static configured, a copy of 
   * the IP information is set to the old IP information. When IP lost timer expires, the old IP 
   * information is reset to 0.
   *
   * @param[in]  tcpip_if: the interface which we want to set old IP information
   * @param[in]  ip_info: store the IP information which needs to be set to specified interface
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_set_old_ip_info(tcpip_adapter_if_t tcpip_if, tcpip_adapter_ip_info_t *ip_info);
  
  
  /**
   * @brief  create interface's linklocal IPv6 information
   *
   * @note this function will create a linklocal IPv6 address about input interface,
   *       if this address status changed to preferred, will call event call back ,
   *       notify user linklocal IPv6 address has been verified
   *
   * @param[in]  tcpip_if: the interface which we want to set IP information
   *
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_create_ip6_linklocal(tcpip_adapter_if_t tcpip_if);
  
  #if TCPIP_ADAPTER_IPV6
  /**
   * @brief  get interface's linkloacl IPv6 information
   *
   * There has an IPv6 information copy in adapter library, if interface is up,and IPv6 info
   * is preferred,it will get IPv6 linklocal IP successfully
   *
   * @param[in]  tcpip_if: the interface which we want to set IP information
   * @param[in]  if_ip6: If successful, IPv6 information will be returned in this argument.
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_get_ip6_linklocal(tcpip_adapter_if_t tcpip_if, ip6_addr_t *if_ip6);
  
  /**
   * @brief get interface's global IPv6 information
   *
   * @param[in]  tcpip_if: the interface which we want to set IP information
   * @param[in]  if_ip6: If successful, IPv6 information will be returned in this argument.
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_get_ip6_global(tcpip_adapter_if_t tcpip_if, ip6_addr_t *if_ip6);
  #endif
  
  #if 0
  esp_err_t tcpip_adapter_get_mac(tcpip_adapter_if_t tcpip_if, uint8_t *mac);
  
  esp_err_t tcpip_adapter_set_mac(tcpip_adapter_if_t tcpip_if, uint8_t *mac);
  #endif
  
  /**
   * @brief  Get DHCP server's status
   *
   * @param[in]   tcpip_if: the interface which we will get status of DHCP server
   * @param[out]  status: If successful, the status of DHCP server will be return in this argument.
   *
   * @return ESP_OK
   */
  esp_err_t tcpip_adapter_dhcps_get_status(tcpip_adapter_if_t tcpip_if, tcpip_adapter_dhcp_status_t *status);
  
  /**
   * @brief  Set or Get DHCP server's option
   *
   * @param[in]  opt_op: option operate type, 1 for SET, 2 for GET.
   * @param[in]  opt_id: option index, 32 for ROUTER, 50 for IP POLL, 51 for LEASE TIME, 52 for REQUEST TIME
   * @param[in]  opt_val: option parameter
   * @param[in]  opt_len: option length
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STOPPED
   *         ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STARTED
   */
  esp_err_t tcpip_adapter_dhcps_option(tcpip_adapter_option_mode_t opt_op, tcpip_adapter_option_id_t opt_id, void *opt_val, uint32_t opt_len);
  
  /**
   * @brief  Start DHCP server
   *
   * @note   Currently DHCP server is bind to softAP interface.
   *
   * @param[in]  tcpip_if: the interface which we will start DHCP server
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STARTED
   */
  esp_err_t tcpip_adapter_dhcps_start(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Stop DHCP server
   *
   * @note   Currently DHCP server is bind to softAP interface.
   *
   * @param[in]  tcpip_if: the interface which we will stop DHCP server
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STOPED
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY
   */
  esp_err_t tcpip_adapter_dhcps_stop(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Get DHCP client status
   *
   * @param[in]  tcpip_if: the interface which we will get status of DHCP client
   * @param[out]  status: If successful, the status of DHCP client will be return in this argument.
   *
   * @return ESP_OK
   */
  esp_err_t tcpip_adapter_dhcpc_get_status(tcpip_adapter_if_t tcpip_if, tcpip_adapter_dhcp_status_t *status);
  
  /**
   * @brief  Set or Get DHCP client's option
   *
   * @note   This function is not implement now.
   *
   * @param[in]  opt_op: option operate type, 1 for SET, 2 for GET.
   * @param[in]  opt_id: option index, 32 for ROUTER, 50 for IP POLL, 51 for LEASE TIME, 52 for REQUEST TIME
   * @param[in]  opt_val: option parameter
   * @param[in]  opt_len: option length
   *
   * @return ESP_OK
   */
  esp_err_t tcpip_adapter_dhcpc_option(tcpip_adapter_option_mode_t opt_op, tcpip_adapter_option_id_t opt_id, void *opt_val, uint32_t opt_len);
  
  /**
   * @brief  Start DHCP client
   *
   * @note   Currently DHCP client is bind to station interface.
   *
   * @param[in]  tcpip_if: the interface which we will start DHCP client
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STARTED
   *         ESP_ERR_TCPIP_ADAPTER_DHCPC_START_FAILED
   */
  esp_err_t tcpip_adapter_dhcpc_start(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Stop DHCP client
   *
   * @note   Currently DHCP client is bind to station interface.
   *
   * @param[in]  tcpip_if: the interface which we will stop DHCP client
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   *         ESP_ERR_TCPIP_ADAPTER_DHCP_ALREADY_STOPED
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY
   */
  esp_err_t tcpip_adapter_dhcpc_stop(tcpip_adapter_if_t tcpip_if);
  
  
  
  esp_err_t tcpip_adapter_eth_input(void *buffer, uint16_t len, void *eb);
  
  /**
   * @brief  Get data from station interface
   *
   * This function should be installed by esp_wifi_reg_rxcb, so WiFi packets will be forward to TCPIP stack.
   *
   * @param[in]  buffer: the received data point
   * @param[in]  len: the received data length
   * @param[in]  eb: parameter
   *
   * @return ESP_OK
   */
  esp_err_t tcpip_adapter_sta_input(void *buffer, uint16_t len, void *eb);
  
  /**
   * @brief  Get data from softAP interface
   *
   * This function should be installed by esp_wifi_reg_rxcb, so WiFi packets will be forward to TCPIP stack.
   *
   * @param[in]  buffer: the received data point
   * @param[in]  len: the received data length
   * @param[in]  eb: parameter
   *
   * @return ESP_OK
   */
  esp_err_t tcpip_adapter_ap_input(void *buffer, uint16_t len, void *eb);
  
  /**
   * @brief  Get WiFi interface index
   *
   * Get WiFi interface from TCPIP interface struct pointer.
   *
   * @param[in]  dev: adapter interface
   *
   * @return ESP_IF_WIFI_STA
   *         ESP_IF_WIFI_AP
             ESP_IF_ETH
   *         ESP_IF_MAX
   */
  esp_interface_t tcpip_adapter_get_esp_if(void *dev);
  
  /**
   * @brief  Get the station information list
   *
   * @param[in]   wifi_sta_list: station list info
   * @param[out]  tcpip_sta_list: station list info
   *
   * @return ESP_OK
   *         ESP_ERR_TCPIP_ADAPTER_NO_MEM
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS
   */
  esp_err_t tcpip_adapter_get_sta_list(wifi_sta_list_t *wifi_sta_list, tcpip_adapter_sta_list_t *tcpip_sta_list);
  
  #define TCPIP_HOSTNAME_MAX_SIZE    32
  /**
   * @brief  Set the hostname to the interface
   *
   * @param[in]   tcpip_if: the interface which we will set the hostname
   * @param[in]   hostname: the host name for set the interface, the max length of hostname is 32 bytes
   *
   * @return ESP_OK:success
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY:interface status error
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS:parameter error
   */
  esp_err_t tcpip_adapter_set_hostname(tcpip_adapter_if_t tcpip_if, const char *hostname);
  
  /**
   * @brief  Get the hostname from the interface
   *
   * @param[in]   tcpip_if: the interface which we will get the hostname
   * @param[in]   hostname: the host name from the interface
   *
   * @return ESP_OK:success
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY:interface status error
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS:parameter error
   */
  esp_err_t tcpip_adapter_get_hostname(tcpip_adapter_if_t tcpip_if, const char **hostname);
  
  /**
   * @brief  Get the LwIP netif* that is assigned to the interface
   *
   * @param[in]   tcpip_if: the interface which we will get the hostname
   * @param[out]  netif: pointer to fill the resulting interface
   *
   * @return ESP_OK:success
   *         ESP_ERR_TCPIP_ADAPTER_IF_NOT_READY:interface status error
   *         ESP_ERR_TCPIP_ADAPTER_INVALID_PARAMS:parameter error
   */
  esp_err_t tcpip_adapter_get_netif(tcpip_adapter_if_t tcpip_if, void ** netif);
  
  
  /**
   * @brief  Test if supplied interface is up or down
   *
   * @param[in]   tcpip_if: the interface which we will get the hostname
   *
   * @return  true:  tcpip_if is UP
   *          false: tcpip_if id DOWN
   */
  bool tcpip_adapter_is_netif_up(tcpip_adapter_if_t tcpip_if);
  
  /**
   * @brief  Install default event handlers for Wi-Fi interfaces (station and AP)
   * @return
   *      - ESP_OK on success
   *      - one of the errors from esp_event on failure
   */
  esp_err_t tcpip_adapter_set_default_wifi_handlers();
  
  /**
   * @brief  Uninstall default event handlers for Wi-Fi interfaces (station and AP)
   * @return
   *      - ESP_OK on success
   *      - one of the errors from esp_event on failure
   */
  esp_err_t tcpip_adapter_clear_default_wifi_handlers();
  
  /**
   * @brief  Search nefit index through netif interface
   * @param[in]   tcpip_if Interface to search for netif index
   * @return
   *      - netif_index on success
   *      - -1 if an invalid parameter is supplied
   */
  int tcpip_adapter_get_netif_index(tcpip_adapter_if_t tcpip_if);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /*  _TCPIP_ADAPTER_H_ */
  
  