1--- 2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3SPDX-License-Identifier: curl 4Title: CURLOPT_ALTSVC 5Section: 3 6Source: libcurl 7See-also: 8 - CURLOPT_ALTSVC_CTRL (3) 9 - CURLOPT_CONNECT_TO (3) 10 - CURLOPT_COOKIEFILE (3) 11 - CURLOPT_RESOLVE (3) 12Protocol: 13 - HTTP 14--- 15<!-- markdown-link-check-disable --> 16# NAME 17 18CURLOPT_ALTSVC - alt-svc cache filename 19 20# SYNOPSIS 21 22~~~c 23#include <curl/curl.h> 24 25CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC, char *filename); 26~~~ 27 28# DESCRIPTION 29 30Pass in a pointer to a *filename* to instruct libcurl to use that file as 31the Alt-Svc cache to read existing cache contents from and possibly also write 32it back to after a transfer, unless **CURLALTSVC_READONLYFILE** is set in 33CURLOPT_ALTSVC_CTRL(3). 34 35Specify a blank filename ("") to make libcurl not load from a file at all. 36 37# DEFAULT 38 39NULL. The alt-svc cache is not read nor written to file. 40 41# EXAMPLE 42 43~~~c 44int main(void) 45{ 46 CURL *curl = curl_easy_init(); 47 if(curl) { 48 curl_easy_setopt(curl, CURLOPT_ALTSVC_CTRL, CURLALTSVC_H1); 49 curl_easy_setopt(curl, CURLOPT_ALTSVC, "altsvc-cache.txt"); 50 curl_easy_perform(curl); 51 } 52} 53~~~ 54 55# FILE FORMAT 56 57A text based file with one line per alt-svc entry and each line consists of 58nine space-separated fields. 59 60An example line could look like 61 62 h2 www.example.com 8443 h3 second.example.com 443 "20190808 06:18:37" 1 0 63 64The fields of that line are: 65 66## h2 67 68ALPN id for the source origin 69 70## www.example.comp 71 72Hostname for the source origin 73 74## 8443 75 76Port number for the source origin 77 78## h3 79 80ALPN id for the destination host 81 82## second.example.com 83 84Hostname for the destination host 85 86## 443 87 88Port number for the destination host 89 90## 2019* 91 92Expiration date and time of this entry within double quotes. The date format 93is "YYYYMMDD HH:MM:SS" and the time zone is GMT. 94 95## 1 96 97Boolean (1 or 0) if "persist" was set for this entry 98 99## 0 100 101Integer priority value (not currently used) 102 103# AVAILABILITY 104 105Added in 7.64.1 106 107# RETURN VALUE 108 109Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. 110
