1# Alt-Svc
2
3curl features **EXPERIMENTAL** support for the Alt-Svc: HTTP header.
4
5## Enable Alt-Svc in build
6
7`./configure --enable-alt-svc`
8
9## Standard
10
11[RFC 7838](https://tools.ietf.org/html/rfc7838)
12
13# Alt-Svc cache file format
14
15This a text based file with one line per entry and each line consists of nine
16space separated fields.
17
18## Example
19
20    h2 quic.tech 8443 h3-22 quic.tech 8443 "20190808 06:18:37" 0 0
21
22## Fields
23
241. The ALPN id for the source origin
252. The host name for the source origin
263. The port number for the source origin
274. The ALPN id for the destination host
285. The host name for the destination host
296. The host number for the destination host
307. The expiration date and time of this entry withing double quotes. The date format is "YYYYMMDD HH:MM:SS" and the time zone is GMT.
318. Boolean (1 or 0) if "persist" was set for this entry
329. Integer priority value (not currently used)
33
34# TODO
35
36- handle multiple response headers, when one of them says `clear` (should
37  override them all)
38- using `Age:` value for caching age as per spec
39- `CURLALTSVC_IMMEDIATELY` support
40