CURLOPT_HSTSREADFUNCTION

Section: curl_easy_setopt options (3)
Updated: November 04, 2020
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NAME

CURLOPT_HSTSREADFUNCTION - read callback for HSTS hosts

SYNOPSIS

CURLSTScode hstsread(CURL *easy, struct curl_hstsentry *sts, void *userp);

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTSREADFUNCTION, hstsread);

EXPERIMENTAL

Warning: this feature is early code and is marked as experimental. It can only be enabled by explicitly telling configure with --enable-hsts. You are advised to not ship this in production before the experimental label is removed.

DESCRIPTION

Pass a pointer to your callback function, as the prototype shows above.

This callback function gets called by libcurl repeatedly when it populates the in-memory HSTS cache.

Set the userp argument with the CURLOPT_HSTSREADDATA(3) option or it will be NULL.

When this callback is invoked, the sts pointer points to a populated struct: Copy the host name to 'name' (no longer than 'namelen' bytes). Make it null-terminated. Set 'includeSubDomains' to TRUE or FALSE. Set 'expire' to a date stamp or a zero length string for *forever* (wrong date stamp format might cause the name to not get accepted)

The callback should return CURLSTS_OK if it returns a name and is prepared to be called again (for another host) or CURLSTS_DONE if it has no entry to return. It can also return CURLSTS_FAIL to signal error.

This option doesn't enable HSTS, you need to use CURLOPT_HSTS_CTRL(3) to do that.

DEFAULT

NULL - no callback.

PROTOCOLS

This feature is only used for HTTP(S) transfer.

EXAMPLE

{
  /* set HSTS read callback */
  curl_easy_setopt(curl, CURLOPT_HSTSREADFUNCTION, hstsread);

  /* pass in suitable argument to the callback */
  curl_easy_setopt(curl, CURLOPT_HSTSREADDATA, &hstspreload[0]);

  result = curl_easy_perform(curl);
}

AVAILABILITY

Added in 7.74.0

RETURN VALUE

This will return CURLE_OK.