CURLOPT_HSTSREADDATA(3)

CURLOPT_HSTSREADDATA3

Pointer passed to the hsts read callback

Usage

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTSREADDATA, void *pointer);

Overview

Data pointer to pass to the HSTS read function. If you use the CURLOPT_HSTSREADFUNCTION(3) option, this is the pointer you get as input in the 3rd argument to the callback.

This option does not enable HSTS, you need to use CURLOPT_HSTS_CTRL(3) to do that.

Default

NULL

Protocols

This functionality affects http only

Examples

struct MyData {
  void *custom;
};
static CURLSTScode hsts_cb(CURL *easy, struct curl_hstsentry *sts,
                           void *clientp)
{
  /* populate the struct as documented */
  return CURLSTS_OK;
}
int main(void)
{
  CURL *curl = curl_easy_init();
  struct MyData my_data;
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
    /* pass pointer that gets passed in to the
       CURLOPT_HSTSREADFUNCTION callback */
    curl_easy_setopt(curl, CURLOPT_HSTSREADDATA, &my_data);
    /* set HSTS read callback */
    curl_easy_setopt(curl, CURLOPT_HSTSREADFUNCTION, hsts_cb);
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Return value

This returns CURLE_OK.

Releases

4 releases since Debian 11 (Bullseye); the text changed 3 times.

  1. 11
  2. 12
  3. 13
  4. Arch

Availability

Added in curl 7.74.0

From curl 8.23.0-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.