esp-idf/components/esp_http_client/include/esp_http_client.h

/*
 * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#ifndef _ESP_HTTP_CLIENT_H
#define _ESP_HTTP_CLIENT_H

#include "freertos/FreeRTOS.h"
#include "sdkconfig.h"
#include "esp_err.h"
#include <sys/socket.h>

#ifdef __cplusplus
extern "C" {
#endif

#define DEFAULT_HTTP_BUF_SIZE (512)

typedef struct esp_http_client *esp_http_client_handle_t;
typedef struct esp_http_client_event *esp_http_client_event_handle_t;

/**
 * @brief   HTTP Client events id
 */
typedef enum {
    HTTP_EVENT_ERROR = 0,       /*!< This event occurs when there are any errors during execution */
    HTTP_EVENT_ON_CONNECTED,    /*!< Once the HTTP has been connected to the server, no data exchange has been performed */
    HTTP_EVENT_HEADERS_SENT,     /*!< After sending all the headers to the server */
    HTTP_EVENT_HEADER_SENT = HTTP_EVENT_HEADERS_SENT, /*!< This header has been kept for backward compatability
                                                           and will be deprecated in future versions esp-idf */
    HTTP_EVENT_ON_HEADER,       /*!< Occurs when receiving each header sent from the server */
    HTTP_EVENT_ON_DATA,         /*!< Occurs when receiving data from the server, possibly multiple portions of the packet */
    HTTP_EVENT_ON_FINISH,       /*!< Occurs when finish a HTTP session */
    HTTP_EVENT_DISCONNECTED,    /*!< The connection has been disconnected */
    HTTP_EVENT_REDIRECT,        /*!< Intercepting HTTP redirects to handle them manually */
} esp_http_client_event_id_t;

/**
 * @brief      HTTP Client events data
 */
typedef struct esp_http_client_event {
    esp_http_client_event_id_t event_id;    /*!< event_id, to know the cause of the event */
    esp_http_client_handle_t client;        /*!< esp_http_client_handle_t context */
    void *data;                             /*!< data of the event */
    int data_len;                           /*!< data length of data */
    void *user_data;                        /*!< user_data context, from esp_http_client_config_t user_data */
    char *header_key;                       /*!< For HTTP_EVENT_ON_HEADER event_id, it's store current http header key */
    char *header_value;                     /*!< For HTTP_EVENT_ON_HEADER event_id, it's store current http header value */
} esp_http_client_event_t;


/**
 * @brief      HTTP Client transport
 */
typedef enum {
    HTTP_TRANSPORT_UNKNOWN = 0x0,   /*!< Unknown */
    HTTP_TRANSPORT_OVER_TCP,        /*!< Transport over tcp */
    HTTP_TRANSPORT_OVER_SSL,        /*!< Transport over ssl */
} esp_http_client_transport_t;

typedef esp_err_t (*http_event_handle_cb)(esp_http_client_event_t *evt);

/**
 * @brief HTTP method
 */
typedef enum {
    HTTP_METHOD_GET = 0,    /*!< HTTP GET Method */
    HTTP_METHOD_POST,       /*!< HTTP POST Method */
    HTTP_METHOD_PUT,        /*!< HTTP PUT Method */
    HTTP_METHOD_PATCH,      /*!< HTTP PATCH Method */
    HTTP_METHOD_DELETE,     /*!< HTTP DELETE Method */
    HTTP_METHOD_HEAD,       /*!< HTTP HEAD Method */
    HTTP_METHOD_NOTIFY,     /*!< HTTP NOTIFY Method */
    HTTP_METHOD_SUBSCRIBE,  /*!< HTTP SUBSCRIBE Method */
    HTTP_METHOD_UNSUBSCRIBE,/*!< HTTP UNSUBSCRIBE Method */
    HTTP_METHOD_OPTIONS,    /*!< HTTP OPTIONS Method */
    HTTP_METHOD_COPY,       /*!< HTTP COPY Method */
    HTTP_METHOD_MOVE,       /*!< HTTP MOVE Method */
    HTTP_METHOD_LOCK,       /*!< HTTP LOCK Method */
    HTTP_METHOD_UNLOCK,     /*!< HTTP UNLOCK Method */
    HTTP_METHOD_PROPFIND,   /*!< HTTP PROPFIND Method */
    HTTP_METHOD_PROPPATCH,  /*!< HTTP PROPPATCH Method */
    HTTP_METHOD_MKCOL,      /*!< HTTP MKCOL Method */
    HTTP_METHOD_MAX,
} esp_http_client_method_t;

/**
 * @brief HTTP Authentication type
 */
typedef enum {
    HTTP_AUTH_TYPE_NONE = 0,    /*!< No authention */
    HTTP_AUTH_TYPE_BASIC,       /*!< HTTP Basic authentication */
    HTTP_AUTH_TYPE_DIGEST,      /*!< HTTP Disgest authentication */
} esp_http_client_auth_type_t;

/**
 * @brief HTTP configuration
 */
typedef struct {
    const char                  *url;                /*!< HTTP URL, the information on the URL is most important, it overrides the other fields below, if any */
    const char                  *host;               /*!< Domain or IP as string */
    int                         port;                /*!< Port to connect, default depend on esp_http_client_transport_t (80 or 443) */
    const char                  *username;           /*!< Using for Http authentication */
    const char                  *password;           /*!< Using for Http authentication */
    esp_http_client_auth_type_t auth_type;           /*!< Http authentication type, see `esp_http_client_auth_type_t` */
    const char                  *path;               /*!< HTTP Path, if not set, default is `/` */
    const char                  *query;              /*!< HTTP query */
    const char                  *cert_pem;           /*!< SSL server certification, PEM format as string, if the client requires to verify server */
    size_t                      cert_len;            /*!< Length of the buffer pointed to by cert_pem. May be 0 for null-terminated pem */
    const char                  *client_cert_pem;    /*!< SSL client certification, PEM format as string, if the server requires to verify client */
    size_t                      client_cert_len;     /*!< Length of the buffer pointed to by client_cert_pem. May be 0 for null-terminated pem */
    const char                  *client_key_pem;     /*!< SSL client key, PEM format as string, if the server requires to verify client */
    size_t                      client_key_len;      /*!< Length of the buffer pointed to by client_key_pem. May be 0 for null-terminated pem */
    const char                  *client_key_password;      /*!< Client key decryption password string */
    size_t                      client_key_password_len;   /*!< String length of the password pointed to by client_key_password */
    const char                  *user_agent;         /*!< The User Agent string to send with HTTP requests */
    esp_http_client_method_t    method;                   /*!< HTTP Method */
    int                         timeout_ms;               /*!< Network timeout in milliseconds */
    bool                        disable_auto_redirect;    /*!< Disable HTTP automatic redirects */
    int                         max_redirection_count;    /*!< Max number of redirections on receiving HTTP redirect status code, using default value if zero*/
    int                         max_authorization_retries;    /*!< Max connection retries on receiving HTTP unauthorized status code, using default value if zero. Disables authorization retry if -1*/
    http_event_handle_cb        event_handler;             /*!< HTTP Event Handle */
    esp_http_client_transport_t transport_type;           /*!< HTTP transport type, see `esp_http_client_transport_t` */
    int                         buffer_size;              /*!< HTTP receive buffer size */
    int                         buffer_size_tx;           /*!< HTTP transmit buffer size */
    void                        *user_data;               /*!< HTTP user_data context */
    bool                        is_async;                 /*!< Set asynchronous mode, only supported with HTTPS for now */
    bool                        use_global_ca_store;      /*!< Use a global ca_store for all the connections in which this bool is set. */
    bool                        skip_cert_common_name_check;    /*!< Skip any validation of server certificate CN field */
    const char                  *common_name;             /*!< Pointer to the string containing server certificate common name.
                                                               If non-NULL, server certificate CN must match this name,
                                                               If NULL, server certificate CN must match hostname. */
    esp_err_t (*crt_bundle_attach)(void *conf);      /*!< Function pointer to esp_crt_bundle_attach. Enables the use of certification
                                                          bundle for server verification, must be enabled in menuconfig */
    bool                        keep_alive_enable;   /*!< Enable keep-alive timeout */
    int                         keep_alive_idle;     /*!< Keep-alive idle time. Default is 5 (second) */
    int                         keep_alive_interval; /*!< Keep-alive interval time. Default is 5 (second) */
    int                         keep_alive_count;    /*!< Keep-alive packet retry send count. Default is 3 counts */
    struct ifreq                *if_name;            /*!< The name of interface for data to go through. Use the default interface without setting */
} esp_http_client_config_t;

/**
 * Enum for the HTTP status codes.
 */
typedef enum {
    /* 2xx - Success */
    HttpStatus_Ok                = 200,

    /* 3xx - Redirection */
    HttpStatus_MultipleChoices   = 300,
    HttpStatus_MovedPermanently  = 301,
    HttpStatus_Found             = 302,
    HttpStatus_SeeOther          = 303,
    HttpStatus_TemporaryRedirect = 307,
    HttpStatus_PermanentRedirect = 308,

    /* 4xx - Client Error */
    HttpStatus_BadRequest        = 400,
    HttpStatus_Unauthorized      = 401,
    HttpStatus_Forbidden         = 403,
    HttpStatus_NotFound          = 404,

    /* 5xx - Server Error */
    HttpStatus_InternalError     = 500
} HttpStatus_Code;

#define ESP_ERR_HTTP_BASE               (0x7000)                    /*!< Starting number of HTTP error codes */
#define ESP_ERR_HTTP_MAX_REDIRECT       (ESP_ERR_HTTP_BASE + 1)     /*!< The error exceeds the number of HTTP redirects */
#define ESP_ERR_HTTP_CONNECT            (ESP_ERR_HTTP_BASE + 2)     /*!< Error open the HTTP connection */
#define ESP_ERR_HTTP_WRITE_DATA         (ESP_ERR_HTTP_BASE + 3)     /*!< Error write HTTP data */
#define ESP_ERR_HTTP_FETCH_HEADER       (ESP_ERR_HTTP_BASE + 4)     /*!< Error read HTTP header from server */
#define ESP_ERR_HTTP_INVALID_TRANSPORT  (ESP_ERR_HTTP_BASE + 5)     /*!< There are no transport support for the input scheme */
#define ESP_ERR_HTTP_CONNECTING         (ESP_ERR_HTTP_BASE + 6)     /*!< HTTP connection hasn't been established yet */
#define ESP_ERR_HTTP_EAGAIN             (ESP_ERR_HTTP_BASE + 7)     /*!< Mapping of errno EAGAIN to esp_err_t */
#define ESP_ERR_HTTP_CONNECTION_CLOSED  (ESP_ERR_HTTP_BASE + 8)     /*!< Read FIN from peer and the connection closed */

/**
 * @brief      Start a HTTP session
 *             This function must be the first function to call,
 *             and it returns a esp_http_client_handle_t that you must use as input to other functions in the interface.
 *             This call MUST have a corresponding call to esp_http_client_cleanup when the operation is complete.
 *
 * @param[in]  config   The configurations, see `http_client_config_t`
 *
 * @return
 *     - `esp_http_client_handle_t`
 *     - NULL if any errors
 */
esp_http_client_handle_t esp_http_client_init(const esp_http_client_config_t *config);

/**
 * @brief      Invoke this function after `esp_http_client_init` and all the options calls are made, and will perform the
 *             transfer as described in the options. It must be called with the same esp_http_client_handle_t as input as the esp_http_client_init call returned.
 *             esp_http_client_perform performs the entire request in either blocking or non-blocking manner. By default, the API performs request in a blocking manner and returns when done,
 *             or if it failed, and in non-blocking manner, it returns if EAGAIN/EWOULDBLOCK or EINPROGRESS is encountered, or if it failed. And in case of non-blocking request,
 *             the user may call this API multiple times unless request & response is complete or there is a failure. To enable non-blocking esp_http_client_perform(), `is_async` member of esp_http_client_config_t
 *             must be set while making a call to esp_http_client_init() API.
 *             You can do any amount of calls to esp_http_client_perform while using the same esp_http_client_handle_t. The underlying connection may be kept open if the server allows it.
 *             If you intend to transfer more than one file, you are even encouraged to do so.
 *             esp_http_client will then attempt to re-use the same connection for the following transfers, thus making the operations faster, less CPU intense and using less network resources.
 *             Just note that you will have to use `esp_http_client_set_**` between the invokes to set options for the following esp_http_client_perform.
 *
 * @note       You must never call this function simultaneously from two places using the same client handle.
 *             Let the function return first before invoking it another time.
 *             If you want parallel transfers, you must use several esp_http_client_handle_t.
 *             This function include `esp_http_client_open` -> `esp_http_client_write` -> `esp_http_client_fetch_headers` -> `esp_http_client_read` (and option) `esp_http_client_close`.
 *
 * @param      client  The esp_http_client handle
 *
 * @return
 *  - ESP_OK on successful
 *  - ESP_FAIL on error
 */
esp_err_t esp_http_client_perform(esp_http_client_handle_t client);

/**
 * @brief      Set URL for client, when performing this behavior, the options in the URL will replace the old ones
 *
 * @param[in]  client  The esp_http_client handle
 * @param[in]  url     The url
 *
 * @return
 *  - ESP_OK
 *  - ESP_FAIL
 */
esp_err_t esp_http_client_set_url(esp_http_client_handle_t client, const char *url);

/**
 * @brief      Set post data, this function must be called before `esp_http_client_perform`.
 *             Note: The data parameter passed to this function is a pointer and this function will not copy the data
 *
 * @param[in]  client  The esp_http_client handle
 * @param[in]  data    post data pointer
 * @param[in]  len     post length
 *
 * @return
 *  - ESP_OK
 *  - ESP_FAIL
 */
esp_err_t esp_http_client_set_post_field(esp_http_client_handle_t client, const char *data, int len);

/**
 * @brief      Get current post field information
 *
 * @param[in]  client  The client
 * @param[out] data    Point to post data pointer
 *
 * @return     Size of post data
 */
int esp_http_client_get_post_field(esp_http_client_handle_t client, char **data);

/**
 * @brief      Set http request header, this function must be called after esp_http_client_init and before any
 *             perform function
 *
 * @param[in]  client  The esp_http_client handle
 * @param[in]  key     The header key
 * @param[in]  value   The header value
 *
 * @return
 *  - ESP_OK
 *  - ESP_FAIL
 */
esp_err_t esp_http_client_set_header(esp_http_client_handle_t client, const char *key, const char *value);

/**
 * @brief      Get http request header.
 *             The value parameter will be set to NULL if there is no header which is same as
 *             the key specified, otherwise the address of header value will be assigned to value parameter.
 *             This function must be called after `esp_http_client_init`.
 *
 * @param[in]  client  The esp_http_client handle
 * @param[in]  key     The header key
 * @param[out] value   The header value
 *
 * @return
 *     - ESP_OK
 *     - ESP_FAIL
 */
esp_err_t esp_http_client_get_header(esp_http_client_handle_t client, const char *key, char **value);

/**
 * @brief      Get http request username.
 *             The address of username buffer will be assigned to value parameter.
 *             This function must be called after `esp_http_client_init`.
 *
 * @param[in]  client  The esp_http_client handle
 * @param[out] value   The username value
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_get_username(esp_http_client_handle_t client, char **value);

/**
 * @brief      Set http request username.
 *             The value of username parameter will be assigned to username buffer.
 *             If the username parameter is NULL then username buffer will be freed.
 *
 * @param[in]  client    The esp_http_client handle
 * @param[in]  username  The username value
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_set_username(esp_http_client_handle_t client, const char *username);

/**
 * @brief      Get http request password.
 *             The address of password buffer will be assigned to value parameter.
 *             This function must be called after `esp_http_client_init`.
 *
 * @param[in]  client  The esp_http_client handle
 * @param[out] value   The password value
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_get_password(esp_http_client_handle_t client, char **value);

/**
 * @brief      Set http request password.
 *             The value of password parameter will be assigned to password buffer.
 *             If the password parameter is NULL then password buffer will be freed.
 *
 * @param[in]  client    The esp_http_client handle
 * @param[in]  password  The password value
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_set_password(esp_http_client_handle_t client, const char *password);

/**
 * @brief      Set http request auth_type.
 *
 * @param[in]  client    The esp_http_client handle
 * @param[in]  auth_type The esp_http_client auth type
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_set_authtype(esp_http_client_handle_t client, esp_http_client_auth_type_t auth_type);

/**
 * @brief      Get HTTP client session errno
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return
 *         - (-1) if invalid argument
 *         - errno
 */
int esp_http_client_get_errno(esp_http_client_handle_t client);

/**
 * @brief      Set http request method
 *
 * @param[in]  client  The esp_http_client handle
 * @param[in]  method  The method
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_set_method(esp_http_client_handle_t client, esp_http_client_method_t method);

/**
 * @brief      Set http request timeout
 *
 * @param[in]  client      The esp_http_client handle
 * @param[in]  timeout_ms  The timeout value
 *
 * @return
 *     - ESP_OK
 *     - ESP_ERR_INVALID_ARG
 */
esp_err_t esp_http_client_set_timeout_ms(esp_http_client_handle_t client, int timeout_ms);

/**
 * @brief      Delete http request header
 *
 * @param[in]  client  The esp_http_client handle
 * @param[in]  key     The key
 *
 * @return
 *  - ESP_OK
 *  - ESP_FAIL
 */
esp_err_t esp_http_client_delete_header(esp_http_client_handle_t client, const char *key);

/**
 * @brief      This function will be open the connection, write all header strings and return
 *
 * @param[in]  client     The esp_http_client handle
 * @param[in]  write_len  HTTP Content length need to write to the server
 *
 * @return
 *  - ESP_OK
 *  - ESP_FAIL
 */
esp_err_t esp_http_client_open(esp_http_client_handle_t client, int write_len);

/**
 * @brief     This function will write data to the HTTP connection previously opened by esp_http_client_open()
 *
 * @param[in]  client  The esp_http_client handle
 * @param      buffer  The buffer
 * @param[in]  len     This value must not be larger than the write_len parameter provided to esp_http_client_open()
 *
 * @return
 *     - (-1) if any errors
 *     - Length of data written
 */
int esp_http_client_write(esp_http_client_handle_t client, const char *buffer, int len);

/**
 * @brief      This function need to call after esp_http_client_open, it will read from http stream, process all receive headers
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return
 *     - (0) if stream doesn't contain content-length header, or chunked encoding (checked by `esp_http_client_is_chunked` response)
 *     - (-1: ESP_FAIL) if any errors
 *     - (-ESP_ERR_HTTP_EAGAIN = -0x7007) if call is timed-out before any data was ready
 *     - Download data length defined by content-length header
 */
int64_t esp_http_client_fetch_headers(esp_http_client_handle_t client);


/**
 * @brief      Check response data is chunked
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return     true or false
 */
bool esp_http_client_is_chunked_response(esp_http_client_handle_t client);

/**
 * @brief      Read data from http stream
 *
 * @param[in]  client  The esp_http_client handle
 * @param      buffer  The buffer
 * @param[in]  len     The length
 *
 * @return
 *     - (-1) if any errors
 *     - Length of data was read
 *
 * @note  (-ESP_ERR_HTTP_EAGAIN = -0x7007) is returned when call is timed-out before any data was ready
 */
int esp_http_client_read(esp_http_client_handle_t client, char *buffer, int len);


/**
 * @brief      Get http response status code, the valid value if this function invoke after `esp_http_client_perform`
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return     Status code
 */
int esp_http_client_get_status_code(esp_http_client_handle_t client);

/**
 * @brief      Get http response content length (from header Content-Length)
 *             the valid value if this function invoke after `esp_http_client_perform`
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return
 *     - (-1) Chunked transfer
 *     - Content-Length value as bytes
 */
int64_t esp_http_client_get_content_length(esp_http_client_handle_t client);

/**
 * @brief      Close http connection, still kept all http request resources
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return
 *     - ESP_OK
 *     - ESP_FAIL
 */
esp_err_t esp_http_client_close(esp_http_client_handle_t client);

/**
 * @brief      This function must be the last function to call for an session.
 *             It is the opposite of the esp_http_client_init function and must be called with the same handle as input that a esp_http_client_init call returned.
 *             This might close all connections this handle has used and possibly has kept open until now.
 *             Don't call this function if you intend to transfer more files, re-using handles is a key to good performance with esp_http_client.
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return
 *     - ESP_OK
 *     - ESP_FAIL
 */
esp_err_t esp_http_client_cleanup(esp_http_client_handle_t client);

/**
 * @brief      Get transport type
 *
 * @param[in]  client   The esp_http_client handle
 *
 * @return
 *     - HTTP_TRANSPORT_UNKNOWN
 *     - HTTP_TRANSPORT_OVER_TCP
 *     - HTTP_TRANSPORT_OVER_SSL
 */
esp_http_client_transport_t esp_http_client_get_transport_type(esp_http_client_handle_t client);

/**
 * @brief      Set redirection URL.
 *             When received the 30x code from the server, the client stores the redirect URL provided by the server.
 *             This function will set the current URL to redirect to enable client to execute the redirection request.
 *
 * @param[in]  client  The esp_http_client handle
 *
 * @return
 *     - ESP_OK
 *     - ESP_FAIL
 */
esp_err_t esp_http_client_set_redirection(esp_http_client_handle_t client);

/**
 * @brief      On receiving HTTP Status code 401, this API can be invoked to add authorization
 *             information.
 *
 * @note       There is a possibility of receiving body message with redirection status codes, thus make sure
 *             to flush off body data after calling this API.
 *
 * @param[in]  client   The esp_http_client handle
 */
void esp_http_client_add_auth(esp_http_client_handle_t client);

/**
 * @brief      Checks if entire data in the response has been read without any error.
 *
 * @param[in]  client   The esp_http_client handle
 *
 * @return
 *     - true
 *     - false
 */
bool esp_http_client_is_complete_data_received(esp_http_client_handle_t client);

/**
 * @brief      Helper API to read larger data chunks
 *             This is a helper API which internally calls `esp_http_client_read` multiple times till the end of data is reached or till the buffer gets full.
 *
 * @param[in]  client   The esp_http_client handle
 * @param      buffer   The buffer
 * @param[in]  len      The buffer length
 *
 * @return
 *     - Length of data was read
 */

int esp_http_client_read_response(esp_http_client_handle_t client, char *buffer, int len);

/**
 * @brief       Process all remaining response data
 *              This uses an internal buffer to repeatedly receive, parse, and discard response data until complete data is processed.
 *              As no additional user-supplied buffer is required, this may be preferrable to `esp_http_client_read_response` in situations where the content of the response may be ignored.
 *
 * @param[in]  client  The esp_http_client handle
 * @param      len     Length of data discarded
 *
 * @return
 *     - ESP_OK                 If successful, len will have discarded length
 *     - ESP_FAIL               If failed to read response
 *     - ESP_ERR_INVALID_ARG    If the client is NULL
 */
esp_err_t esp_http_client_flush_response(esp_http_client_handle_t client, int *len);

/**
 * @brief          Get URL from client
 *
 * @param[in]      client   The esp_http_client handle
 * @param[inout]   url      The buffer to store URL
 * @param[in]      len      The buffer length
 *
 * @return
 *     - ESP_OK
 *     - ESP_FAIL
 */

esp_err_t esp_http_client_get_url(esp_http_client_handle_t client, char *url, const int len);

/**
 * @brief          Get Chunk-Length from client
 *
 * @param[in]      client   The esp_http_client handle
 * @param[out]     len      Variable to store length
 *
 * @return
 *     - ESP_OK                 If successful, len will have length of current chunk
 *     - ESP_FAIL               If the server is not a chunked server
 *     - ESP_ERR_INVALID_ARG    If the client or len are NULL
 */
esp_err_t esp_http_client_get_chunk_length(esp_http_client_handle_t client, int *len);

#ifdef __cplusplus
}
#endif


#endif