.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2022, Daniel Stenberg, , et al. .\" * .\" * This software is licensed as described in the file COPYING, which .\" * you should have received as part of this distribution. The terms .\" * are also available at https://curl.se/docs/copyright.html. .\" * .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell .\" * copies of the Software, and permit persons to whom the Software is .\" * furnished to do so, under the terms of the COPYING file. .\" * .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY .\" * KIND, either express or implied. .\" * .\" ************************************************************************** .\" .TH CURLOPT_HSTSREADFUNCTION 3 "14 Sep 2020" "libcurl 7.74.0" "curl_easy_setopt options" .SH NAME CURLOPT_HSTSREADFUNCTION \- read callback for HSTS hosts .SH SYNOPSIS .nf #include 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 *userp); CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTSREADFUNCTION, hstsread); .fi .SH 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 \fIuserp\fP argument with the \fICURLOPT_HSTSREADDATA(3)\fP option or it will be NULL. When this callback is invoked, the \fIsts\fP 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 \fICURLSTS_OK\fP if it returns a name and is prepared to be called again (for another host) or \fICURLSTS_DONE\fP if it has no entry to return. It can also return \fICURLSTS_FAIL\fP to signal error. Returning \fICURLSTS_FAIL\fP will stop the transfer from being performed and make \fICURLE_ABORTED_BY_CALLBACK\fP get returned. This option does not enable HSTS, you need to use \fICURLOPT_HSTS_CTRL(3)\fP to do that. .SH DEFAULT NULL - no callback. .SH PROTOCOLS This feature is only used for HTTP(S) transfer. .SH EXAMPLE .nf { /* 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); } .fi .SH AVAILABILITY Added in 7.74.0 .SH RETURN VALUE This will return CURLE_OK. .SH "SEE ALSO" .BR CURLOPT_HSTSREADDATA "(3), " CURLOPT_HSTSWRITEFUNCTION "(3), " .BR CURLOPT_HSTS "(3), " CURLOPT_HSTS_CTRL "(3), "