http2: allow sending 1xx responses

Currently, it's not possible to send informational responses such as
103 Early Hints or 102 Processing.

This patch allows calling WriteHeader() multiple times in order
to send informational responses before the final one.

If the status code is in the 1xx range, the current content of the header map
is also sent. Its content is not removed after the call to WriteHeader()
because the headers must also be included in the final response.

The Chrome and Fastly teams are starting a large-scale experiment to measure
the real-life impact of the 103 status code.
Using Early Hints is proposed as a (partial) alternative to Server Push,
which are going to be removed from Chrome:

Being able to send this status code from servers implemented using Go would
help to see if implementing it in browsers is worth it.

Fixes golang/go#26089.
Fixes golang/go#36734.
Updates golang/go#26088.

Change-Id: Iadb7be92844a3588ef4ce044f887ef5c1792f431
GitHub-Last-Rev: eee95b58b3b259781fc1052ed6143a0aa9284e04
GitHub-Pull-Request: golang/net#96
Run-TryBot: Damien Neil <>
Reviewed-by: Dmitri Shuralyov <>
Reviewed-by: Damien Neil <>
TryBot-Result: Gopher Robot <>
2 files changed
tree: b9d33d01fb32ca626c3be880943a880bdf2ead01
  1. bpf/
  2. context/
  3. dict/
  4. dns/
  5. html/
  6. http/
  7. http2/
  8. icmp/
  9. idna/
  10. internal/
  11. ipv4/
  12. ipv6/
  13. lif/
  14. nettest/
  15. netutil/
  16. proxy/
  17. publicsuffix/
  18. route/
  19. trace/
  20. webdav/
  21. websocket/
  22. xsrftoken/
  23. .gitattributes
  24. .gitignore
  26. codereview.cfg
  29. go.mod
  30. go.sum

Go Networking

Go Reference

This repository holds supplementary Go networking libraries.


The easiest way to install is to run go get -u You can also manually git clone the repository to $GOPATH/src/

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see The main issue tracker for the net repository is located at Prefix your issue with “x/net:” in the subject line, so it is easy to find.