1<!-- 2Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3 4SPDX-License-Identifier: curl 5--> 6 7# Alt-Svc 8 9curl features support for the Alt-Svc: HTTP header. 10 11## Enable Alt-Svc in build 12 13`./configure --enable-alt-svc` 14 15(enabled by default since 7.73.0) 16 17## Standard 18 19[RFC 7838](https://datatracker.ietf.org/doc/html/rfc7838) 20 21# Alt-Svc cache file format 22 23This is a text based file with one line per entry and each line consists of nine 24space separated fields. 25 26## Example 27 28 h2 quic.tech 8443 h3-22 quic.tech 8443 "20190808 06:18:37" 0 0 29 30## Fields 31 321. The ALPN id for the source origin 332. The hostname for the source origin 343. The port number for the source origin 354. The ALPN id for the destination host 365. The hostname for the destination host 376. The port number for the destination host 387. The expiration date and time of this entry within double quotes. The date format is "YYYYMMDD HH:MM:SS" and the time zone is GMT. 398. Boolean (1 or 0) if "persist" was set for this entry 409. Integer priority value (not currently used) 41 42If the hostname is an IPv6 numerical address, it is stored with brackets such 43as `[::1]`. 44
