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.

Development Status

nghttp2 was originally developed based on RFC 7540 <https://tools.ietf.org/html/rfc7540>_ HTTP/2 and RFC 7541 <https://tools.ietf.org/html/rfc7541>_ HPACK - Header Compression for HTTP/2. Now we are updating our code to implement RFC 9113 <https://datatracker.ietf.org/doc/html/rfc9113>_.

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 and HTTP/3)

  This endpoint supports h2 and http/1.1 via ALPN and requires TLSv1.2 for HTTP/2 connection.

  It also supports HTTP/3.

• 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 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 >= 1.1.1; or wolfSSL >= 5.7.0; or LibreSSL >= 3.8.1; or aws-lc >= 1.19.0; or BoringSSL
• libev >= 4.11
• zlib >= 1.2.3
• libc-ares >= 1.7.5

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 <https://github.com/nghttp2/nghttp2/issues/762>_.

For BoringSSL or aws-lc build, to enable :rfc:8879 TLS Certificate Compression in applications, the following library is required:

• libbrotli-dev >= 1.0.9

To enable mruby support for nghttpx, mruby <https://github.com/mruby/mruby>_ is required. We need to build mruby with C++ ABI explicitly turned on, and probably need other mrgems, mruby is managed 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 <https://github.com/h2o/neverbleed>_, privilege separation engine for OpenSSL. 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.

To enable the experimental HTTP/3 support for h2load and nghttpx, the following libraries are required:

• quictls <https://github.com/quictls/openssl/tree/OpenSSL_1_1_1w+quic>; or wolfSSL; or LibreSSL (does not support 0RTT); or aws-lc; or BoringSSL <https://boringssl.googlesource.com/boringssl/> (commit 52975ff6ea9fb076e53025b82f2e80a23b027a5c); or OpenSSL >= 3.5.0
• ngtcp2 <https://github.com/ngtcp2/ngtcp2>_ >= 1.16.0
• nghttp3 <https://github.com/ngtcp2/nghttp3>_ >= 1.12.0

Use --enable-http3 configure option to enable HTTP/3 feature for h2load and nghttpx.

In order to build optional eBPF program to direct an incoming QUIC UDP datagram to a correct socket for nghttpx, the following libraries are required:

• libbpf-dev >= 0.7.0

Use --with-libbpf configure option to build eBPF program. libelf-dev is needed to build libbpf.

For Ubuntu 20.04, you can build libbpf from the source code <https://github.com/libbpf/libbpf/releases>_. nghttpx requires eBPF program for reloading its configuration and hot swapping its executable.

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, C++20 compliant compiler is required. At least g++ >= 12 and clang++ >= 18 are known to work.

.. note::

To enable mruby support in nghttpx, and use --with-mruby configure option.

.. note::

Mac OS X users may need the --disable-threads configure option to disable multi-threading in nghttpd, nghttpx and h2load to prevent them from crashing. A patch is welcome to make multi threading work on Mac OS X platform.

.. note::

To compile the associated applications (nghttp, nghttpd, nghttpx and h2load), you must use the --enable-app configure option and ensure that the specified requirements above are met. Normally, configure script checks required dependencies to build these applications, and enable --enable-app automatically, so you don't have to use it explicitly. But if you found that applications were not built, then using --enable-app may find that cause, such as the missing dependency.

.. note::

In order to detect third party libraries, pkg-config is used (however we don't use pkg-config for some libraries (e.g., libev)). By default, pkg-config searches *.pc file in the standard locations (e.g., /usr/lib/pkgconfig). If it is necessary to use *.pc file in the custom location, specify paths to PKG_CONFIG_PATH environment variable, and pass it to configure script, like so:

.. code-block:: text

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

For pkg-config managed libraries, *_CFLAG and *_LIBS environment variables are defined (e.g., OPENSSL_CFLAGS, OPENSSL_LIBS). Specifying non-empty string to these variables completely overrides pkg-config. In other words, if they are specified, pkg-config is not used for detection, and user is responsible to specify the correct values to these variables. For complete list of these variables, run ./configure -h.

If you are using Ubuntu 22.04 LTS, run the following to install the required packages:

.. code-block:: text

sudo apt-get install g++ clang make binutils autoconf automake \
  autotools-dev libtool pkg-config \
  zlib1g-dev libssl-dev libxml2-dev libev-dev \
  libevent-dev libjansson-dev \
  libc-ares-dev libjemalloc-dev libsystemd-dev \
  ruby-dev bison libelf-dev

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 <https://github.com/nghttp2/nghttp2/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:

.. code-block:: text

$ 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:

.. code-block:: text

$ 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 <https://cmake.org/>. The free version of Visual C++ Build Tools <http://landinghub.visualstudio.com/visual-cpp-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:

.. code-block:: text

$ 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:

.. code-block:: text

nghttpx: error while l