curl-w32/docs/libcurl/opts/CURLOPT_HSTSREADFUNCTION.md

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---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_HSTSREADFUNCTION
Section: 3
Source: libcurl
See-also:
- CURLOPT_HSTS (3)
- CURLOPT_HSTSREADDATA (3)
- CURLOPT_HSTSWRITEFUNCTION (3)
- CURLOPT_HSTS_CTRL (3)
---
# NAME
CURLOPT_HSTSREADFUNCTION - read callback for HSTS hosts
# SYNOPSIS
~~~c
#include <curl/curl.h>
struct curl_hstsentry {
char *name;
size_t namelen;
unsigned int includeSubDomains:1;
char expire[18]; /* YYYYMMDD HH:MM:SS [null-terminated] */
};
CURLSTScode hstsread(CURL *easy, struct curl_hstsentry *sts, void *clientp);
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTSREADFUNCTION, hstsread);
~~~
# 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 *clientp* argument with the CURLOPT_HSTSREADDATA(3) option
or it is NULL.
When this callback is invoked, the *sts* pointer points to a populated
struct: Copy the hostname 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. Returning *CURLSTS_FAIL* stops the transfer from being performed
and make *CURLE_ABORTED_BY_CALLBACK* get returned.
This option does not 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
~~~c
struct priv {
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();
if(curl) {
struct priv my_stuff;
CURLcode res;
/* set HSTS read callback */
curl_easy_setopt(curl, CURLOPT_HSTSREADFUNCTION, hsts_cb);
/* pass in suitable argument to the callback */
curl_easy_setopt(curl, CURLOPT_HSTSREADDATA, &my_stuff);
res = curl_easy_perform(curl);
}
}
~~~
# AVAILABILITY
Added in 7.74.0
# RETURN VALUE
This returns CURLE_OK.