mirror of
https://github.com/moparisthebest/curl
synced 2024-12-23 00:28:48 -05:00
fa8d7ce4fe
Changed the support to a little matrix and added brief explanation of what ALPN and NPN are for.
63 lines
2.1 KiB
Plaintext
63 lines
2.1 KiB
Plaintext
|
|
HTTP2 with libcurl
|
|
|
|
Spec: http://tools.ietf.org/html/draft-ietf-httpbis-http2
|
|
|
|
nghttp2 (https://github.com/tatsuhiro-t/nghttp2)
|
|
|
|
libcurl uses this 3rd party library for the low level protocol handling
|
|
parts. The reason for this is that HTTP2 is much more complex at that layer
|
|
than HTTP1.1 (which we implement on our own) and that nghttp2 is an already
|
|
existing and well functional library.
|
|
|
|
Right now, nghttp2 implements http2 draft-09
|
|
|
|
We require at least version 0.3.0
|
|
|
|
Over an http:// URL
|
|
|
|
If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will include
|
|
an upgrade header in the initial request to the host to allow upgrading to
|
|
http2.
|
|
|
|
Possibly we can later introduce an option that will cause libcurl to fail if
|
|
not possible to upgrade. Possibly we introduce an option that makes libcurl
|
|
use http2 at once over http://
|
|
|
|
Over an https:// URL
|
|
|
|
If CURLOPT_HTTP_VERSION is set to CURL_HTTP_VERSION_2, libcurl will use ALPN
|
|
(or NPN) to negotiate which protocol to continue with. Possibly introduce an
|
|
option that will cause libcurl to fail if not possible to use http2.
|
|
Consider options to explicitly disable ALPN and/or NPN.
|
|
|
|
ALPN is the TLS extension that http2 is expected to use. The NPN extension
|
|
is for a similar purpose, was made prior to ALPN and is used for SPDY so
|
|
early http2 servers are implemented using NPN before ALPN support is
|
|
widespread.
|
|
|
|
SSL libs
|
|
|
|
The challenge is the ALPN and NPN support and all our different SSL
|
|
backends. You may need a fairly updated SSL library version for it to
|
|
provide the necessary TLS features. Right now we support:
|
|
|
|
OpenSSL: ALPN and NPN
|
|
NSS: ALPN and NPN
|
|
GnuTLS: ALPN
|
|
|
|
Applications
|
|
|
|
We hide http2's binary nature and convert received http2 traffic to headers
|
|
in HTTP 1.1 style. This allows applications to work unmodified.
|
|
|
|
curl tool
|
|
|
|
curl offers the --http2 command line option to enable use of http2
|
|
|
|
To consider:
|
|
|
|
- How to tell libcurl when using the multi interface that all or some of the
|
|
handles are allowed to re-use the same physical connection. Can we just
|
|
re-use existing pipelining logic?
|