curl / libcurl / API / curl_easy_getinfo / CURLINFO_EARLYDATA_SENT_T

CURLINFO_EARLYDATA_SENT_T explained

Name

CURLINFO_EARLYDATA_SENT_T - get the number of bytes sent as TLS early data

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_EARLYDATA_SENT_T,
                           curl_off_t *amount);

Description

Pass a pointer to an curl_off_t to receive the total amount of bytes that were sent to the server as TLSv1.3 early data. When no TLS early data is used, this reports 0.

TLS early data is only attempted when CURLSSLOPT_EARLYDATA is set for the transfer. In addition, it is only used by libcurl when a TLS session exists that announces support.

The amount is negative when the sent data was rejected by the server. TLS allows a server that announces support for early data to reject any attempt to use it at its own discretion. When for example 127 bytes had been sent, but were rejected, it reports -127 as the amount "sent".

Protocols

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

This option works only with the following TLS backends: GnuTLS

Example

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 
    /* Perform the request */
    res = curl_easy_perform(curl);
 
    if(!res) {
      curl_off_t amount;
      res = curl_easy_getinfo(curl, CURLINFO_EARLYDATA_SENT_T, &amount);
      if(!res) {
        printf("TLS earlydata: %" CURL_FORMAT_CURL_OFF_T " bytes\n", amount);
      }
    }
  }
}

Availability

Added in curl 8.11.0

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.