nghttp2 - HTTP/2 C Library

This is an implementation of the Hypertext Transfer Protocol version 2 in C.

The framing layer of HTTP/2 is implemented as a reusable C library. On top of that, we have implemented an HTTP/2 client, server and proxy. We have also developed load test and benchmarking tools for HTTP/2.

An HPACK encoder and decoder are available as a public API.

An experimental high level C++ library is also available.

We have Python bindings of this library, but we do not have full code coverage yet.

Development Status

We have implemented RFC 7540 HTTP/2 and RFC 7541 HPACK - Header Compression for HTTP/2

The nghttp2 code base was forked from the spdylay (https://github.com/tatsuhiro-t/spdylay) project.

Public Test Server

The following endpoints are available to try out our nghttp2 implementation.

• https://nghttp2.org/ (TLS + ALPN/NPN)

  This endpoint supports h2, h2-16, h2-14, and http/1.1 via ALPN/NPN and requires TLSv1.2 for HTTP/2 connection.

• http://nghttp2.org/ (HTTP Upgrade and HTTP/2 Direct)

  h2c and http/1.1.

Requirements

The following package is required to build the libnghttp2 library:

• pkg-config >= 0.20

To build and run the unit test programs, the following package is required:

• cunit >= 2.1

To build the documentation, you need to install:

• sphinx (http://sphinx-doc.org/)

If you need libnghttp2 (C library) only, then the above packages are all you need. Use --enable-lib-only to ensure that only libnghttp2 is built. This avoids potential build error related to building bundled applications.

To build and run the application programs (nghttp, nghttpd, nghttpx and h2load) in the src directory, the following packages are required:

• OpenSSL >= 1.0.1
• libev >= 4.11
• zlib >= 1.2.3
• libc-ares >= 1.7.5

ALPN support requires OpenSSL >= 1.0.2 (released 22 January 2015). LibreSSL >= 2.2.0 can be used instead of OpenSSL, but OpenSSL has more features than LibreSSL at the time of this writing.

To enable -a option (getting linked assets from the downloaded resource) in nghttp, the following package is required:

• libxml2 >= 2.6.26

To enable systemd support in nghttpx, the following package is required:

• libsystemd-dev >= 209

The HPACK tools require the following package:

• jansson >= 2.5

To build sources under the examples directory, libevent is required:

• libevent-openssl >= 2.0.8

To mitigate heap fragmentation in long running server programs (nghttpd and nghttpx), jemalloc is recommended:

• jemalloc

  Note

  Alpine Linux currently does not support malloc replacement due to musl limitations. See details in issue #762.

libnghttp2_asio C++ library requires the following packages:

• libboost-dev >= 1.54.0
• libboost-thread-dev >= 1.54.0

The Python bindings require the following packages:

• cython >= 0.19
• python >= 3.8
• python-setuptools

If you are using Ubuntu 16.04 LTS (Xenial Xerus) or Debian 8 (jessie) and above, run the following to install the required packages:

sudo apt-get install g++ make binutils autoconf automake autotools-dev libtool pkg-config \
  zlib1g-dev libcunit1-dev libssl-dev libxml2-dev libev-dev libevent-dev libjansson-dev \
  libc-ares-dev libjemalloc-dev libsystemd-dev \
  cython python3-dev python-setuptools

To enable mruby support for nghttpx, mruby is required. We need to build mruby with C++ ABI explicitly turned on, and probably need other mrgems, mruby is manged by git submodule under third-party/mruby directory. Currently, mruby support for nghttpx is disabled by default. To enable mruby support, use --with-mruby configure option. Note that at the time of this writing, libmruby-dev and mruby packages in Debian/Ubuntu are not usable for nghttp2, since they do not enable C++ ABI. To build mruby, the following packages are required:

• ruby
• bison

nghttpx supports neverbleed, privilege separation engine for OpenSSL / LibreSSL. In short, it minimizes the risk of private key leakage when serious bug like Heartbleed is exploited. The neverbleed is disabled by default. To enable it, use --with-neverbleed configure option.

Compiling libnghttp2 C source code requires a C99 compiler. gcc 4.8 is known to be adequate. In order to compile the C++ source code, gcc >= 6.0 or clang >= 6.0 is required. C++ source code requires C++14 language features.

$ ./configure PKG_CONFIG_PATH=/path/to/pkgconfig

Building nghttp2 from release tar archive

The nghttp2 project regularly releases tar archives which includes nghttp2 source code, and generated build files. They can be downloaded from Releases page.

Building nghttp2 from git requires autotools development packages. Building from tar archives does not require them, and thus it is much easier. The usual build step is as follows:

$ tar xf nghttp2-X.Y.Z.tar.bz2
$ cd nghttp2-X.Y.Z
$ ./configure
$ make

Building from git

Building from git is easy, but please be sure that at least autoconf 2.68 is used:

$ git submodule update --init
$ autoreconf -i
$ automake
$ autoconf
$ ./configure
$ make

Notes for building on Windows (MSVC)

The easiest way to build native Windows nghttp2 dll is use cmake. The free version of Visual C++ Build Tools works fine.

1. Install cmake for windows
2. Open "Visual C++ ... Native Build Tool Command Prompt", and inside nghttp2 directly, run cmake.
3. Then run cmake --build to build library.
4. nghttp2.dll, nghttp2.lib, nghttp2.exp are placed under lib directory.

Note that the above steps most likely produce nghttp2 library only. No bundled applications are compiled.

Notes for building on Windows (Mingw/Cygwin)

Under Mingw environment, you can only compile the library, it's libnghttp2-X.dll and libnghttp2.a.

If you want to compile the applications(h2load, nghttp, nghttpx, nghttpd), you need to use the Cygwin environment.

Under Cygwin environment, to compile the applications you need to compile and install the libev first.

Secondly, you need to undefine the macro __STRICT_ANSI__, if you not, the functions fdopen, fileno and strptime will not available.

the sample command like this:

$ export CFLAGS="-U__STRICT_ANSI__ -I$libev_PREFIX/include -L$libev_PREFIX/lib"
$ export CXXFLAGS=$CFLAGS
$ ./configure
$ make

If you want to compile the applications under examples/, you need to remove or rename the event.h from libev's installation, because it conflicts with libevent's installation.

Notes for installation on Linux systems

After installing nghttp2 tool suite with make install one might experience a similar error:

nghttpx: error while loading shared libraries: libnghttp2.so.14: cannot open shared object file: No such file or directory

This means that the tool is unable to locate the libnghttp2.so shared library.

To update the shared library cache run sudo ldconfig.

Building the documentation

To build the documentation, run:

$ make html

The documents will be generated under doc/manual/html/.

The generated documents will not be installed with make install.

The online documentation is available at https://nghttp2.org/documentation/

Unit tests

Unit tests are done by simply running make check.

Integration tests

We have the integration tests for the nghttpx proxy server. The tests are written in the Go programming language and uses its testing framework. We depend on the following libraries:

• golang.org/x/net/http2
• golang.org/x/net/websocket
• https://github.com/tatsuhiro-t/go-nghttp2

Go modules will download these dependencies automatically.

To run the tests, run the following command under integration-tests directory:

$ make it

Inside the tests, we use port 3009 to run the test subject server.

Migration from v0.7.15 or earlier

nghttp2 v1.0.0 introduced several backward incompatible changes. In this section, we describe these changes and how to migrate to v1.0.0.

ALPN protocol ID is now h2 and h2c

Previously we announced h2-14 and h2c-14. v1.0.0 implements final protocol version, and we changed ALPN ID to h2 and h2c. The macros NGHTTP2_PROTO_VERSION_ID, NGHTTP2_PROTO_VERSION_ID_LEN, NGHTTP2_CLEARTEXT_PROTO_VERSION_ID, and NGHTTP2_CLEARTEXT_PROTO_VERSION_ID_LEN have been updated to reflect this change.

Basically, existing applications do not have to do anything, just recompiling is enough for this change.

Use word "client magic" where we use "client connection preface"

We use "client connection preface" to mean first 24 bytes of client connection preface. This is technically not correct, since client connection preface is composed of 24 bytes client magic byte string followed by SETTINGS frame. For clarification, we call "client magic" for this 24 bytes byte string and updated API.

• NGHTTP2_CLIENT_CONNECTION_PREFACE was replaced with NGHTTP2_CLIENT_MAGIC.
• NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN was replaced with NGHTTP2_CLIENT_MAGIC_LEN.
• NGHTTP2_BAD_PREFACE was renamed as NGHTTP2_BAD_CLIENT_MAGIC

The already deprecated NGHTTP2_CLIENT_CONNECTION_HEADER and NGHTTP2_CLIENT_CONNECTION_HEADER_LEN were removed.

If application uses these macros, just replace old ones with new ones. Since v1.0.0, client magic is sent by library (see next subsection), so client application may just remove these macro use.

Client magic is sent by library

Previously nghttp2 library did not send client magic, which is first 24 bytes byte string of client connection preface, and client applications have to send it by themselves. Since v1.0.0, client magic is sent by library via first call of nghttp2_session_send() or nghttp2_session_mem_send().

The client applications which send client magic must remove the relevant code.

Remove HTTP Alternative Services (Alt-Svc) related code

Alt-Svc specification is not finalized yet. To make our API stable, we have decided to remove all Alt-Svc related API from nghttp2.

• NGHTTP2_EXT_ALTSVC was removed.
• nghttp2_ext_altsvc was removed.

We have already removed the functionality of Alt-Svc in v0.7 series and they have been essentially noop. The application using these macro and struct, remove those lines.

Use nghttp2_error in nghttp2_on_invalid_frame_recv_callback

Previously nghttp2_on_invalid_frame_recv_cb_called took the error_code, defined in nghttp2_error_code, as parameter. But they are not detailed enough to debug. Therefore, we decided to use more detailed nghttp2_error values instead.

The application using this callback should update the callback signature. If it treats error_code as HTTP/2 error code, update the code so that it is treated as nghttp2_error.

Receive client magic by default

Previously nghttp2 did not process client magic (24 bytes byte string). To make it deal with it, we had to use nghttp2_option_set_recv_client_preface(). Since v1.0.0, nghttp2 processes client magic by default and nghttp2_option_set_recv_client_preface() was removed.

Some application may want to disable this behaviour, so we added nghttp2_option_set_no_recv_client_magic() to achieve this.

The application using nghttp2_option_set_recv_client_preface() with nonzero value, just remove it.

The application using nghttp2_option_set_recv_client_preface() with zero value or not using it must use nghttp2_option_set_no_recv_client_magic() with nonzero value.

Client, Server and Proxy programs

The src directory contains the HTTP/2 client, server and proxy programs.

nghttp - client

nghttp is a HTTP/2 client. It can connect to the HTTP/2 server with prior knowledge, HTTP Upgrade and NPN/ALPN TLS extension.

It has verbose output mode for framing information. Here is sample output from nghttp client:

$ nghttp -nv https://nghttp2.org
[  0.190] Connected
The negotiated protocol: h2
[  0.212] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
[  0.212] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
[  0.212] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
          (dep_stream_id=0, weight=201, exclusive=0)
[  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
          (dep_stream_id=0, weight=101, exclusive=0)
[  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
          (dep_stream_id=0, weight=1, exclusive=0)
[  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
          (dep_stream_id=7, weight=1, exclusive=0)
[  0.212] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
          (dep_stream_id=3, weight=1, exclusive=0)
[  0.212] send HEADERS frame <length=39, flags=0x25, stream_id=13>
          ; END_STREAM | END_HEADERS | PRIORITY
          (padlen=0, dep_stream_id=11, weight=16, exclusive=0)
          ; Open new stream
          :method: GET
          :path: /
          :scheme: https
          :authority: nghttp2.org
          accept: */*
          accept-encoding: gzip, deflate
          user-agent: nghttp2/1.0.1-DEV
[  0.221] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.221] recv (stream_id=13) :method: GET
[  0.221] recv (stream_id=13) :scheme: https
[  0.221] recv (stream_id=13) :path: /stylesheets/screen.css
[  0.221] recv (stream_id=13) :authority: nghttp2.org
[  0.221] recv (stream_id=13) accept-encoding: gzip, deflate
[  0.222] recv (stream_id=13) user-agent: nghttp2/1.0.1-DEV
[  0.222] recv PUSH_PROMISE frame <length=50, flags=0x04, stream_id=13>
          ; END_HEADERS
          (padlen=0, promised_stream_id=2)
[  0.222] recv (stream_id=13) :status: 200
[  0.222] recv (stream_id=13) date: Thu, 21 May 2015 16:38:14 GMT
[  0.222] recv (stream_id=13) content-type: text/html
[  0.222] recv (stream_id=13) last-modified: Fri, 15 May 2015 15:38:06 GMT
[  0.222] recv (stream_id=13) etag: W/"555612de-19f6"
[  0.222] recv (stream_id=13) link: </stylesheets/screen.css>; rel=preload; as=stylesheet
[  0.222] recv (stream_id=13) content-encoding: gzip
[  0.222] recv (stream_id=13) server: nghttpx nghttp2/1.0.1-DEV
[  0.222] recv (stream_id=13) via: 1.1 nghttpx
[  0.222] recv (stream_id=13) strict-transport-security: max-age=31536000
[  0.222] recv HEADERS frame <length=166, flags=0x04, stream_id=13>
          ; END_HEADERS
          (padlen=0)
          ; First response header
[  0.222] recv DATA frame <length=2601, flags=0x01, stream_id=13>
          ; END_STREAM
[  0.222] recv (stream_id=2) :status: 200
[  0.222] recv (stream_id=2) date: Thu, 21 May 2015 16:38:14 GMT
[  0.222] recv (stream_id=2) content-type: text/css
[  0.222] recv (stream_id=2) last-modified: Fri, 15 May 2015 15:38:06 GMT
[  0.222] recv (stream_id=2) etag: W/"555612de-9845"
[  0.222] recv (stream_id=2) content-encoding: gzip
[  0.222] recv (stream_id=2) server: nghttpx nghttp2/1.0.1-DEV
[  0.222] recv (stream_id=2) via: 1.1 nghttpx
[  0.222] recv (stream_id=2) strict-transport-security: max-age=31536000
[  0.222] recv HEADERS frame <length=32, flags=0x04, stream_id=2>
          ; END_HEADERS
          (padlen=0)
          ; First push response header
[  0.228] recv DATA frame <length=8715, flags=0x01, stream_id=2>
          ; END_STREAM
[  0.228] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
          (last_stream_id=2, error_code=NO_ERROR(0x00), opaque_data(0)=[])

The HTTP Upgrade is performed like so:

$ nghttp -nvu http://nghttp2.org
[  0.011] Connected
[  0.011] HTTP Upgrade request
GET / HTTP/1.1
Host: nghttp2.org
Connection: Upgrade, HTTP2-Settings
Upgrade: h2c
HTTP2-Settings: AAMAAABkAAQAAP__
Accept: */*
User-Agent: nghttp2/1.0.1-DEV


[  0.018] HTTP Upgrade response
HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Upgrade: h2c


[  0.018] HTTP Upgrade success
[  0.018] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
[  0.018] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
[  0.018] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
          (dep_stream_id=0, weight=201, exclusive=0)
[  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
          (dep_stream_id=0, weight=101, exclusive=0)
[  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
          (dep_stream_id=0, weight=1, exclusive=0)
[  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
          (dep_stream_id=7, weight=1, exclusive=0)
[  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
          (dep_stream_id=3, weight=1, exclusive=0)
[  0.018] send PRIORITY frame <length=5, flags=0x00, stream_id=1>
          (dep_stream_id=11, weight=16, exclusive=0)
[  0.019] recv (stream_id=1) :method: GET
[  0.019] recv (stream_id=1) :scheme: http
[  0.019] recv (stream_id=1) :path: /stylesheets/screen.css
[  0.019] recv (stream_id=1) host: nghttp2.org
[  0.019] recv (stream_id=1) user-agent: nghttp2/1.0.1-DEV
[  0.019] recv PUSH_PROMISE frame <length=49, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0, promised_stream_id=2)
[  0.019] recv (stream_id=1) :status: 200
[  0.019] recv (stream_id=1) date: Thu, 21 May 2015 16:39:16 GMT
[  0.019] recv (stream_id=1) content-type: text/html
[  0.019] recv (stream_id=1) content-length: 6646
[  0.019] recv (stream_id=1) last-modified: Fri, 15 May 2015 15:38:06 GMT
[  0.019] recv (stream_id=1) etag: "555612de-19f6"
[  0.019] recv (stream_id=1) link: </stylesheets/screen.css>; rel=preload; as=stylesheet
[  0.019] recv (stream_id=1) accept-ranges: bytes
[  0.019] recv (stream_id=1) server: nghttpx nghttp2/1.0.1-DEV
[  0.019] recv (stream_id=1) via: 1.1 nghttpx
[  0.019] recv HEADERS frame <length=157, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0)
          ; First response header
[  0.019] recv DATA frame <length=6646, flags=0x01, stream_id=1>
          ; END_STREAM
[  0.019] recv (stream_id=2) :status: 200
[  0.019] recv (stream_id=2) date: Thu, 21 May 2015 16:39:16 GMT
[  0.019] recv (stream_id=2) content-type: text/css
[  0.019] recv (stream_id=2) content-length: 38981
[  0.019] recv (stream_id=2) last-modified: Fri, 15 May 2015 15:38:06 GMT
[  0.019] recv (stream_id=2) etag: "555612de-9845"
[  0.019] recv (stream_id=2) accept-ranges: bytes
[  0.019] recv (stream_id=2) server: nghttpx nghttp2/1.0.1-DEV
[  0.019] recv (stream_id=2) via: 1.1 nghttpx
[  0.019] recv HEADERS frame <length=36, flags=0x04, stream_id=2>
          ; END_HEADERS
          (padlen=0)
          ; First push response header
[  0.026] recv DATA frame <length=16384, flags=0x00, stream_id=2>
[  0.027] recv DATA frame <length=7952, flags=0x00, stream_id=2>
[  0.027] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
          (window_size_increment=33343)
[  0.032] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=2>
          (window_size_increment=33707)
[  0.032] recv DATA frame <length=14645, flags=0x01, stream_id=2>
          ; END_STREAM
[  0.032] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.032] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
          (last_stream_id=2, error_code=NO_ERROR(0x00), opaque_data(0)=[])

Using the -s option, nghttp prints out some timing information for requests, sorted by completion time:

$ nghttp -nas https://nghttp2.org/
***** Statistics *****

Request timing:
  responseEnd: the  time  when  last  byte of  response  was  received
               relative to connectEnd
 requestStart: the time  just before  first byte  of request  was sent
               relative  to connectEnd.   If  '*' is  shown, this  was
               pushed by server.
      process: responseEnd - requestStart
         code: HTTP status code
         size: number  of  bytes  received as  response  body  without
               inflation.
          URI: request URI

see http://www.w3.org/TR/resource-timing/#processing-model

sorted by 'complete'

id  responseEnd requestStart  process code size request path
 13    +37.19ms       +280us  36.91ms  200   2K /
  2    +72.65ms *   +36.38ms  36.26ms  200   8K /stylesheets/screen.css
 17    +77.43ms     +38.67ms  38.75ms  200   3K /javascripts/octopress.js
 15    +78.12ms     +38.66ms  39.46ms  200   3K /javascripts/modernizr-2.0.js

Using the -r option, nghttp writes more detailed timing data to the given file in HAR format.

nghttpd - server

nghttpd is a multi-threaded static web server.

By default, it uses SSL/TLS connection. Use --no-tls option to disable it.

nghttpd only accepts HTTP/2 connections via NPN/ALPN or direct HTTP/2 connections. No HTTP Upgrade is supported.

The -p option allows users to configure server push.

Just like nghttp, it has a verbose output mode for framing information. Here is sample output from nghttpd:

$ nghttpd --no-tls -v 8080
IPv4: listen 0.0.0.0:8080
IPv6: listen :::8080
[id=1] [  1.521] send SETTINGS frame <length=6, flags=0x00, stream_id=0>
          (niv=1)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
[id=1] [  1.521] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
[id=1] [  1.521] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=3>
          (dep_stream_id=0, weight=201, exclusive=0)
[id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=5>
          (dep_stream_id=0, weight=101, exclusive=0)
[id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=7>
          (dep_stream_id=0, weight=1, exclusive=0)
[id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=9>
          (dep_stream_id=7, weight=1, exclusive=0)
[id=1] [  1.521] recv PRIORITY frame <length=5, flags=0x00, stream_id=11>
          (dep_stream_id=3, weight=1, exclusive=0)
[id=1] [  1.521] recv (stream_id=13) :method: GET
[id=1] [  1.521] recv (stream_id=13) :path: /
[id=1] [  1.521] recv (stream_id=13) :scheme: http
[id=1] [  1.521] recv (stream_id=13) :authority: localhost:8080
[id=1] [  1.521] recv (stream_id=13) accept: */*
[id=1] [  1.521] recv (stream_id=13) accept-encoding: gzip, deflate
[id=1] [  1.521] recv (stream_id=13) user-agent: nghttp2/1.0.0-DEV
[id=1] [  1.521] recv HEADERS frame <length=41, flags=0x25, stream_id=13>
          ; END_STREAM | END_HEADERS | PRIORITY
          (padlen=0, dep_stream_id=11, weight=16, exclusive=0)
          ; Open new stream
[id=1] [  1.521] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[id=1] [  1.521] send HEADERS frame <length=86, flags=0x04, stream_id=13>
          ; END_HEADERS
          (padlen=0)
          ; First response header
          :status: 200
          server: nghttpd nghttp2/1.0.0-DEV
          content-length: 10
          cache-control: max-age=3600
          date: Fri, 15 May 2015 14:49:04 GMT
          last-modified: Tue, 30 Sep 2014 12:40:52 GMT
[id=1] [  1.522] send DATA frame <length=10, flags=0x01, stream_id=13>
          ; END_STREAM
[id=1] [  1.522] stream_id=13 closed
[id=1] [  1.522] recv GOAWAY frame <length=8, flags=0x00, stream_id=0>
          (last_stream_id=0, error_code=NO_ERROR(0x00), opaque_data(0)=[])
[id=1] [  1.522] closed

nghttpx - proxy

nghttpx is a multi-threaded reverse proxy for HTTP/2, and HTTP/1.1, and powers http://nghttp2.org and supports HTTP/2 server push.

We reworked nghttpx command-line interface, and as a result, there are several incompatibles from 1.8.0 or earlier. This is necessary to extend its capability, and secure the further feature enhancements in the future release. Please read Migration from nghttpx v1.8.0 or earlier to know how to migrate from earlier releases.

nghttpx implements important performance-oriented features in TLS, such as session IDs, session tickets (with automatic key rotation), OCSP stapling, dynamic record sizing, ALPN/NPN, forward secrecy and HTTP/2. nghttpx also offers the functionality to share session cache and ticket keys among multiple nghttpx instances via memcached.

nghttpx has 2 operation modes:

The interesting mode at the moment is the default mode. It works like a reverse proxy and listens for HTTP/2, and HTTP/1.1 and can be deployed as a SSL/TLS terminator for existing web server.

In all modes, the frontend connections are encrypted by SSL/TLS by default. To disable encryption, use the no-tls keyword in --frontend option. If encryption is disabled, incoming HTTP/1.1 connections can be upgraded to HTTP/2 through HTTP Upgrade. On the other hard, backend connections are not encrypted by default. To encrypt backend connections, use tls keyword in --backend option.

nghttpx supports a configuration file. See the --conf option and sample configuration file nghttpx.conf.sample.

In the default mode, nghttpx works as reverse proxy to the backend server:

Client <-- (HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/1.1, HTTP/2) --> Web Server
                                [reverse proxy]

With the --http2-proxy option, it works as forward proxy, and it is so called secure HTTP/2 proxy:

Client <-- (HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/1.1) --> Proxy
                                 [secure proxy]          (e.g., Squid, ATS)

The Client in the above example needs to be configured to use nghttpx as secure proxy.

At the time of this writing, both Chrome and Firefox support secure HTTP/2 proxy. One way to configure Chrome to use a secure proxy is to create a proxy.pac script like this:

function FindProxyForURL(url, host) {
    return "HTTPS SERVERADDR:PORT";
}

SERVERADDR and PORT is the hostname/address and port of the machine nghttpx is running on. Please note that Chrome requires a valid certificate for secure proxy.

Then run Chrome with the following arguments:

$ google-chrome --proxy-pac-url=file:///path/to/proxy.pac --use-npn

The backend HTTP/2 connections can be tunneled through an HTTP proxy. The proxy is specified using --backend-http-proxy-uri. The following figure illustrates how nghttpx talks to the outside HTTP/2 proxy through an HTTP proxy:

Client <-- (HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/2) --

        --===================---> HTTP/2 Proxy
          (HTTP proxy tunnel)     (e.g., nghttpx -s)

Benchmarking tool

The h2load program is a benchmarking tool for HTTP/2. The UI of h2load is heavily inspired by weighttp (https://github.com/lighttpd/weighttp). The typical usage is as follows:

$ h2load -n100000 -c100 -m100 https://localhost:8443/
starting benchmark...
spawning thread #0: 100 concurrent clients, 100000 total requests
Protocol: TLSv1.2
Cipher: ECDHE-RSA-AES128-GCM-SHA256
Server Temp Key: ECDH P-256 256 bits
progress: 10% done
progress: 20% done
progress: 30% done
progress: 40% done
progress: 50% done
progress: 60% done
progress: 70% done
progress: 80% done
progress: 90% done
progress: 100% done

finished in 771.26ms, 129658 req/s, 4.71MB/s
requests: 100000 total, 100000 started, 100000 done, 100000 succeeded, 0 failed, 0 errored
status codes: 100000 2xx, 0 3xx, 0 4xx, 0 5xx
traffic: 3812300 bytes total, 1009900 bytes headers, 1000000 bytes data
                     min         max         mean         sd        +/- sd
time for request:    25.12ms    124.55ms     51.07ms     15.36ms    84.87%
time for connect:   208.94ms    254.67ms    241.38ms      7.95ms    63.00%
time to 1st byte:   209.11ms    254.80ms    241.51ms      7.94ms    63.00%

The above example issued total 100,000 requests, using 100 concurrent clients (in other words, 100 HTTP/2 sessions), and a maximum of 100 streams per client. With the -t option, h2load will use multiple native threads to avoid saturating a single core on client side.

HPACK tools

The src directory contains the HPACK tools. The deflatehd program is a command-line header compression tool. The inflatehd program is a command-line header decompression tool. Both tools read input from stdin and write output to stdout. Errors are written to stderr. They take JSON as input and output. We (mostly) use the same JSON data format described at https://github.com/http2jp/hpack-test-case.

deflatehd - header compressor

The deflatehd program reads JSON data or HTTP/1-style header fields from stdin and outputs compressed header block in JSON.

For the JSON input, the root JSON object must include a cases key. Its value has to include the sequence of input header set. They share the same compression context and are processed in the order they appear. Each item in the sequence is a JSON object and it must include a headers key. Its value is an array of JSON objects, which includes exactly one name/value pair.

Example:

{
  "cases":
  [
    {
      "headers": [
        { ":method": "GET" },
        { ":path": "/" }
      ]
    },
    {
      "headers": [
        { ":method": "POST" },
        { ":path": "/" }
      ]
    }
  ]
}

With the -t option, the program can accept more familiar HTTP/1 style header field blocks. Each header set is delimited by an empty line:

Example:

:method: GET
:scheme: https
:path: /

:method: POST
user-agent: nghttp2

The output is in JSON object. It should include a cases key and its value is an array of JSON objects, which has at least the following keys:

seq

The index of header set in the input.

input_length

The sum of the length of the name/value pairs in the input.

output_length

The length of the compressed header block.

percentage_of_original_size

output_length / input_length * 100

wire

The compressed header block as a hex string.

headers

The input header set.

header_table_size

The header table size adjusted before deflating the header set.

Examples:

{
  "cases":
  [
    {
      "seq": 0,
      "input_length": 66,
      "output_length": 20,
      "percentage_of_original_size": 30.303030303030305,
      "wire": "01881f3468e5891afcbf83868a3d856659c62e3f",
      "headers": [
        {
          ":authority": "example.org"
        },
        {
          ":method": "GET"
        },
        {
          ":path": "/"
        },
        {
          ":scheme": "https"
        },
        {
          "user-agent": "nghttp2"
        }
      ],
      "header_table_size": 4096
    }
    ,
    {
      "seq": 1,
      "input_length": 74,
      "output_length": 10,
      "percentage_of_original_size": 13.513513513513514,
      "wire": "88448504252dd5918485",
      "headers": [
        {
          ":authority": "example.org"
        },
        {
          ":method": "POST"
        },
        {
          ":path": "/account"
        },
        {
          ":scheme": "https"
        },
        {
          "user-agent": "nghttp2"
        }
      ],
      "header_table_size": 4096
    }
  ]
}

The output can be used as the input for inflatehd and deflatehd.

With the -d option, the extra header_table key is added and its associated value includes the state of dynamic header table after the corresponding header set was processed. The value includes at least the following keys:

entries

The entry in the header table. If referenced is true, it is in the reference set. The size includes the overhead (32 bytes). The index corresponds to the index of header table. The name is the header field name and the value is the header field value.

size

The sum of the spaces entries occupied, this includes the entry overhead.

max_size

The maximum header table size.

deflate_size

The sum of the spaces entries occupied within max_deflate_size.

max_deflate_size

The maximum header table size the encoder uses. This can be smaller than max_size. In this case, the encoder only uses up to first max_deflate_size buffer. Since the header table size is still max_size, the encoder has to keep track of entries outside the max_deflate_size but inside the max_size and make sure that they are no longer referenced.

Example:

{
  "cases":
  [
    {
      "seq": 0,
      "input_length": 66,
      "output_length": 20,
      "percentage_of_original_size": 30.303030303030305,
      "wire": "01881f3468e5891afcbf83868a3d856659c62e3f",
      "headers": [
        {
          ":authority": "example.org"
        },
        {
          ":method": "GET"
        },
        {
          ":path": "/"
        },
        {
          ":scheme": "https"
        },
        {
          "user-agent": "nghttp2"
        }
      ],
      "header_table_size": 4096,
      "header_table": {
        "entries": [
          {
            "index": 1,
            "name": "user-agent",
            "value": "nghttp2",
            "referenced": true,
            "size": 49
          },
          {
            "index": 2,
            "name": ":scheme",
            "value": "https",
            "referenced": true,
            "size": 44
          },
          {
            "index": 3,
            "name": ":path",
            "value": "/",
            "referenced": true,
            "size": 38
          },
          {
            "index": 4,
            "name": ":method",
            "value": "GET",
            "referenced": true,
            "size": 42
          },
          {
            "index": 5,
            "name": ":authority",
            "value": "example.org",
            "referenced": true,
            "size": 53
          }
        ],
        "size": 226,
        "max_size": 4096,
        "deflate_size": 226,
        "max_deflate_size": 4096
      }
    }
    ,
    {
      "seq": 1,
      "input_length": 74,
      "output_length": 10,
      "percentage_of_original_size": 13.513513513513514,
      "wire": "88448504252dd5918485",
      "headers": [
        {
          ":authority": "example.org"
        },
        {
          ":method": "POST"
        },
        {
          ":path": "/account"
        },
        {
          ":scheme": "https"
        },
        {
          "user-agent": "nghttp2"
        }
      ],
      "header_table_size": 4096,
      "header_table": {
        "entries": [
          {
            "index": 1,
            "name": ":method",
            "value": "POST",
            "referenced": true,
            "size": 43
          },
          {
            "index": 2,
            "name": "user-agent",
            "value": "nghttp2",
            "referenced": true,
            "size": 49
          },
          {
            "index": 3,
            "name": ":scheme",
            "value": "https",
            "referenced": true,
            "size": 44
          },
          {
            "index": 4,
            "name": ":path",
            "value": "/",
            "referenced": false,
            "size": 38
          },
          {
            "index": 5,
            "name": ":method",
            "value": "GET",
            "referenced": false,
            "size": 42
          },
          {
            "index": 6,
            "name": ":authority",
            "value": "example.org",
            "referenced": true,
            "size": 53
          }
        ],
        "size": 269,
        "max_size": 4096,
        "deflate_size": 269,
        "max_deflate_size": 4096
      }
    }
  ]
}

inflatehd - header decompressor

The inflatehd program reads JSON data from stdin and outputs decompressed name/value pairs in JSON.

The root JSON object must include the cases key. Its value has to include the sequence of compressed header blocks. They share the same compression context and are processed in the order they appear. Each item in the sequence is a JSON object and it must have at least a wire key. Its value is a compressed header block as a hex string.

Example:

{
  "cases":
  [
    { "wire": "8285" },
    { "wire": "8583" }
  ]
}

The output is a JSON object. It should include a cases key and its value is an array of JSON objects, which has at least following keys:

seq

The index of the header set in the input.

headers

A JSON array that includes decompressed name/value pairs.

wire

The compressed header block as a hex string.

header_table_size

The header table size adjusted before inflating compressed header block.

Example:

{
  "cases":
  [
    {
      "seq": 0,
      "wire": "01881f3468e5891afcbf83868a3d856659c62e3f",
      "headers": [
        {
          ":authority": "example.org"
        },
        {
          ":method": "GET"
        },
        {
          ":path": "/"
        },
        {
          ":scheme": "https"
        },
        {
          "user-agent": "nghttp2"
        }
      ],
      "header_table_size": 4096
    }
    ,
    {
      "seq": 1,
      "wire": "88448504252dd5918485",
      "headers": [
        {
          ":method": "POST"
        },
        {
          ":path": "/account"
        },
        {
          "user-agent": "nghttp2"
        },
        {
          ":scheme": "https"
        },
        {
          ":authority": "example.org"
        }
      ],
      "header_table_size": 4096
    }
  ]
}

The output can be used as the input for deflatehd and inflatehd.

With the -d option, the extra header_table key is added and its associated value includes the state of the dynamic header table after the corresponding header set was processed. The format is the same as deflatehd.

libnghttp2_asio: High level HTTP/2 C++ library

libnghttp2_asio is C++ library built on top of libnghttp2 and provides high level abstraction API to build HTTP/2 applications. It depends on the Boost::ASIO library and OpenSSL. Currently libnghttp2_asio provides both client and server APIs.

libnghttp2_asio is not built by default. Use the --enable-asio-lib configure flag to build libnghttp2_asio. The required Boost libraries are:

• Boost::Asio
• Boost::System
• Boost::Thread

The server API is designed to build an HTTP/2 server very easily to utilize C++14 anonymous functions and closures. The bare minimum example of an HTTP/2 server looks like this:

#include <iostream>

#include <nghttp2/asio_http2_server.h>

using namespace nghttp2::asio_http2;
using namespace nghttp2::asio_http2::server;

int main(int argc, char *argv[]) {
  boost::system::error_code ec;
  http2 server;

  server.handle("/", [](const request &req, const response &res) {
    res.write_head(200);
    res.end("hello, world\n");
  });

  if (server.listen_and_serve(ec, "localhost", "3000")) {
    std::cerr << "error: " << ec.message() << std::endl;
  }
}

Here is sample code to use the client API:

#include <iostream>

#include <nghttp2/asio_http2_client.h>

using boost::asio::ip::tcp;

using namespace nghttp2::asio_http2;
using namespace nghttp2::asio_http2::client;

int main(int argc, char *argv[]) {
  boost::system::error_code ec;
  boost::asio::io_service io_service;

  // connect to localhost:3000
  session sess(io_service, "localhost", "3000");

  sess.on_connect([&sess](tcp::resolver::iterator endpoint_it) {
    boost::system::error_code ec;

    auto req = sess.submit(ec, "GET", "http://localhost:3000/");

    req->on_response([](const response &res) {
      // print status code and response header fields.
      std::cerr << "HTTP/2 " << res.status_code() << std::endl;
      for (auto &kv : res.header()) {
        std::cerr << kv.first << ": " << kv.second.value << "\n";
      }
      std::cerr << std::endl;

      res.on_data([](const uint8_t *data, std::size_t len) {
        std::cerr.write(reinterpret_cast<const char *>(data), len);
        std::cerr << std::endl;
      });
    });

    req->on_close([&sess](uint32_t error_code) {
      // shutdown session after first request was done.
      sess.shutdown();
    });
  });

  sess.on_error([](const boost::system::error_code &ec) {
    std::cerr << "error: " << ec.message() << std::endl;
  });

  io_service.run();
}

For more details, see the documentation of libnghttp2_asio.

Python bindings

The python directory contains nghttp2 Python bindings. The bindings currently provide HPACK compressor and decompressor classes and an HTTP/2 server.

The extension module is called nghttp2.

make will build the bindings and target Python version is determined by the configure script. If the detected Python version is not what you expect, specify a path to Python executable in a PYTHON variable as an argument to configure script (e.g., ./configure PYTHON=/usr/bin/python3.8).

The following example code illustrates basic usage of the HPACK compressor and decompressor in Python:

import binascii
import nghttp2

deflater = nghttp2.HDDeflater()
inflater = nghttp2.HDInflater()

data = deflater.deflate([(b'foo', b'bar'),
                         (b'baz', b'buz')])
print(binascii.b2a_hex(data))

hdrs = inflater.inflate(data)
print(hdrs)

The nghttp2.HTTP2Server class builds on top of the asyncio event loop. On construction, RequestHandlerClass must be given, which must be a subclass of nghttp2.BaseRequestHandler class.

The BaseRequestHandler class is used to handle the HTTP/2 stream. By default, it does nothing. It must be subclassed to handle each event callback method.

The first callback method invoked is on_headers(). It is called when HEADERS frame, which includes the request header fields, has arrived.

If the request has a request body, on_data(data) is invoked for each chunk of received data.

Once the entire request is received, on_request_done() is invoked.

When the stream is closed, on_close(error_code) is called.

The application can send a response using send_response() method. It can be used in on_headers(), on_data() or on_request_done().

The application can push resources using the push() method. It must be used before the send_response() call.

The following instance variables are available:

client_address

Contains a tuple of the form (host, port) referring to the client's address.

stream_id

Stream ID of this stream.

scheme

Scheme of the request URI. This is a value of :scheme header field.

method

Method of this stream. This is a value of :method header field.

host

This is a value of :authority or host header field.

path

This is a value of :path header field.

The following example illustrates the HTTP2Server and BaseRequestHandler usage:

#!/usr/bin/env python3

import io, ssl
import nghttp2

class Handler(nghttp2.BaseRequestHandler):

    def on_headers(self):
        self.push(path='/css/bootstrap.css',
                  request_headers = [('content-length', '3')],
                  status=200,
                  body='foo')

        self.push(path='/js/bootstrap.js',
                  method='GET',
                  request_headers = [('content-length', '10')],
                  status=200,
                  body='foobarbuzz')

        self.send_response(status=200,
                           headers = [('content-type', 'text/plain')],
                           body=io.BytesIO(b'nghttp2-python FTW'))

ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
ctx.options = ssl.OP_ALL | ssl.OP_NO_SSLv2
ctx.load_cert_chain('server.crt', 'server.key')

# give None to ssl to make the server non-SSL/TLS
server = nghttp2.HTTP2Server(('127.0.0.1', 8443), Handler, ssl=ctx)
server.serve_forever()

Contribution

[This text was composed based on 1.2. License section of curl/libcurl project.]

When contributing with code, you agree to put your changes and new code under the same license nghttp2 is already using unless stated and agreed otherwise.

When changing existing source code, do not alter the copyright of the original file(s). The copyright will still be owned by the original creator(s) or those who have been assigned copyright by the original author(s).

By submitting a patch to the nghttp2 project, you (or your employer, as the case may be) agree to assign the copyright of your submission to us. .. the above really needs to be reworded to pass legal muster. We will credit you for your changes as far as possible, to give credit but also to keep a trace back to who made what changes. Please always provide us with your full real name when contributing!

See Contribution Guidelines for more details.

Reporting vulnerability

If you find a vulnerability in our software, please send the email to "tatsuhiro.t at gmail dot com" about its details instead of submitting issues on github issue page. It is a standard practice not to disclose vulnerability information publicly until a fixed version is released, or mitigation is worked out.

In the future, we may setup a dedicated mail address for this purpose.

Release schedule

In general, we follow Semantic Versioning. We release MINOR version update every month, and usually we ship it around 25th day of every month.

We may release PATCH releases between the regular releases, mainly for severe security bug fixes.

We have no plan to break API compatibility changes involving soname bump, so MAJOR version will stay 1 for the foreseeable future.

License

The MIT License