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

Added in curl 8.11.0

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".

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); } } } }

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

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. This option works only with the following TLS backends: GnuTLS

curl_easy_getinfo(3) returns a CURLcode indicating success or error. CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

curl_easy_getinfo(3), curl_easy_setopt(3) libcurl 2025-06-16 CURLINFO_EARLYDATA_SENT_T(3)

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