1# Alt-Svc
2
3curl features support for the Alt-Svc: HTTP header.
4
5## Enable Alt-Svc in build
6
7`./configure --enable-alt-svc`
8
9(enabled by default since 7.73.0)
10
11## Standard
12
13[RFC 7838](https://tools.ietf.org/html/rfc7838)
14
15# Alt-Svc cache file format
16
17This a text based file with one line per entry and each line consists of nine
18space separated fields.
19
20## Example
21
22    h2 quic.tech 8443 h3-22 quic.tech 8443 "20190808 06:18:37" 0 0
23
24## Fields
25
261. The ALPN id for the source origin
272. The host name for the source origin
283. The port number for the source origin
294. The ALPN id for the destination host
305. The host name for the destination host
316. The host number for the destination host
327. 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.
338. Boolean (1 or 0) if "persist" was set for this entry
349. Integer priority value (not currently used)
35
36# TODO
37
38- handle multiple response headers, when one of them says `clear` (should
39  override them all)
40- using `Age:` value for caching age as per spec
41- `CURLALTSVC_IMMEDIATELY` support
42