esp_http_client_fetch_headers() function

The esp_http_client handle

Get http response status code, the valid value if this function invoke after `esp_http_client_perform`

Get http response content length (from header Content-Length) the valid value if this function invoke after `esp_http_client_perform`

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 reuse 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.

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.

Set http request header, this function must be called after esp_http_client_init and before any perform function

Set http request method

Close http connection, still kept all http request resources

Set URL for client, when performing this behavior, the options in the URL will replace the old ones

Checks if entire data in the response has been read without any error.

Read data from http stream

This function will be open the connection, write all header strings and return

This function will write data to the HTTP connection previously opened by esp_http_client_open()

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

Get current post field information

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. When `disable_auto_redirect` is set, the client will not call this function but the event `HTTP_EVENT_REDIRECT` will be dispatched giving the user control over the redirection event.

Check response data is chunked

On receiving HTTP Status code 401, this API can be invoked to add authorization information.

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.

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`.

Cancel an ongoing HTTP request. This API closes the current socket and opens a new socket with the same esp_http_client context.

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`.

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.

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`.

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.

Set http request auth_type.

Get http request user_data. The value stored from the esp_http_client_config_t will be written to the address passed into data.

Set http request user_data. The value passed in +data+ will be available during event callbacks. No memory management will be performed on the user's behalf.

Get HTTP client session errno

Set http request timeout

Delete http request header

Delete all http request headers

Get transport type

Reset the redirection counter. This is useful to reset redirect counter in cases where the same handle is used for multiple requests.

On receiving a custom authentication header, this API can be invoked to set the authentication information from the header. This API can be called from the event handler.

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 preferable to `esp_http_client_read_response` in situations where the content of the response may be ignored.

Get URL from client

Get Chunk-Length from client