CURLOPT_HSTS.md (2370B)
1 --- 2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3 SPDX-License-Identifier: curl 4 Title: CURLOPT_HSTS 5 Section: 3 6 Source: libcurl 7 Protocol: 8 - HTTP 9 See-also: 10 - CURLOPT_ALTSVC (3) 11 - CURLOPT_HSTS_CTRL (3) 12 - CURLOPT_RESOLVE (3) 13 Added-in: 7.74.0 14 --- 15 16 # NAME 17 18 CURLOPT_HSTS - HSTS cache filename 19 20 # SYNOPSIS 21 22 ~~~c 23 #include <curl/curl.h> 24 25 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTS, char *filename); 26 ~~~ 27 28 # DESCRIPTION 29 30 Make the *filename* point to a filename to load an existing HSTS cache 31 from, and to store the cache in when the easy handle is closed. Setting a file 32 name with this option also enables HSTS for this handle (the equivalent of 33 setting *CURLHSTS_ENABLE* with CURLOPT_HSTS_CTRL(3)). 34 35 If the given file does not exist or contains no HSTS entries at startup, the 36 HSTS cache simply starts empty. Setting the filename to NULL allows HSTS 37 without reading from or writing to any file. NULL also makes libcurl clear the 38 list of files to read HSTS data from, if any such were previously set. 39 40 If this option is set multiple times, libcurl loads cache entries from each 41 given file but only stores the last used name for later writing. 42 43 # FILE FORMAT 44 45 The HSTS cache is saved to and loaded from a text file with one entry per 46 physical line. Each line in the file has the following format: 47 48 [host] [stamp] 49 50 [host] is the domain name for the entry and the name is dot-prefixed if it is 51 an entry valid for all subdomains to the name as well or only for the exact 52 name. 53 54 [stamp] is the time (in UTC) when the entry expires and it uses the format 55 "YYYYMMDD HH:MM:SS". 56 57 Lines starting with "#" are treated as comments and are ignored. There is 58 currently no length or size limit. 59 60 # DEFAULT 61 62 NULL, no filename 63 64 # SECURITY CONCERNS 65 66 libcurl cannot fully protect against attacks where an attacker has write 67 access to the same directory where it is directed to save files. This is 68 particularly sensitive if you save files using elevated privileges. 69 70 # %PROTOCOLS% 71 72 # EXAMPLE 73 74 ~~~c 75 int main(void) 76 { 77 CURL *curl = curl_easy_init(); 78 if(curl) { 79 curl_easy_setopt(curl, CURLOPT_HSTS, "/home/user/.hsts-cache"); 80 curl_easy_perform(curl); 81 } 82 } 83 ~~~ 84 85 # %AVAILABILITY% 86 87 # RETURN VALUE 88 89 curl_easy_setopt(3) returns a CURLcode indicating success or error. 90 91 CURLE_OK (0) means everything was OK, non-zero means an error occurred, see 92 libcurl-errors(3).