nghttp2/README.rst

nghttp2 - HTTP/2.0 C Library
============================

This is an experimental implementation of Hypertext Transfer Protocol
version 2.0.

Development Status
------------------

We started to implement HTTP-draft-09/2.0
(http://tools.ietf.org/html/draft-ietf-httpbis-http2-09) and the
header compression
(http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-05).

The nghttp2 code base was forked from spdylay project.

========================== =================
Features                   HTTP-draft-09/2.0
========================== =================
:authority                 Done
HPACK-draft-05             Done
SETTINGS_HEADER_TABLE_SIZE Done
SETTINGS_ENABLE_PUSH       Done
FRAME_SIZE_ERROR           Done
SETTINGS with ACK          Done
Header Continuation
ALPN                       Done
========================== =================

Public Test Server
------------------

The following endpoints are available to try out nghttp2
implementation.  These endpoints supports ``HTTP-draft-09/2.0`` and
the earlier draft versions are not supporeted.

* https://106.186.112.116 (TLS + NPN)

  NPN offers ``HTTP-draft-09/2.0``, ``spdy/3.1``, ``spdy/3``,
  ``spdy/2`` and ``http/1.1``.

  Note: certificate is self-signed and a browser will show alert

* http://106.186.112.116 (Upgrade + Direct)

Requirements
------------

The following packages are needed to build the library:

* pkg-config >= 0.20
* zlib >= 1.2.3

To build and run the unit test programs, the following packages are
required:

* cunit >= 2.1

To build the documentation, you need to install:

* sphinx (http://sphinx-doc.org/)

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

* OpenSSL >= 1.0.1
* libevent-openssl >= 2.0.8

ALPN support requires unreleased version OpenSSL >= 1.0.2.

To enable SPDY protocol in the application program ``nghttpx``, the
following packages are required:

* spdylay >= 1.2.3

To enable ``-a`` option (getting linked assets from the downloaded
resource) in ``nghttp``, the following packages are needed:

* libxml2 >= 2.7.7

The HPACK tools require the following package:

* jansson >= 2.5

The Python bindings require the following packages:

* cython >= 0.19
* python >= 2.7

If you are using Ubuntu 12.04, you need the following packages
installed:

* autoconf
* automake
* autotools-dev
* libtool
* pkg-config
* zlib1g-dev
* libcunit1-dev
* libssl-dev
* libxml2-dev
* libevent-dev
* libjansson-dev

spdylay is not packaged in Ubuntu, so you need to build it yourself:
http://tatsuhiro-t.github.io/spdylay/

Build from git
--------------

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

    $ autoreconf -i
    $ automake
    $ autoconf
    $ ./configure
    $ make

Building documentation
----------------------

.. note::

   Documentation is still incomplete.

To build 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
http://tatsuhiro-t.github.io/nghttp2/

Client, Server and Proxy programs
---------------------------------

The src directory contains HTTP/2.0 client, server and proxy programs.

nghttp - client
+++++++++++++++

``nghttp`` is a HTTP/2.0 client. It can connect to the HTTP/2.0 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::

    $ src/nghttp -vn https://localhost:8443
    [  0.003] NPN select next protocol: the remote server offers:
	      * HTTP-draft-09/2.0
	      * spdy/3
	      * spdy/2
	      * http/1.1
	      NPN selected the protocol: HTTP-draft-09/2.0
    [  0.005] send SETTINGS frame <length=16, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(4):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(7):65535]
    [  0.006] send HEADERS frame <length=47, flags=0x05, stream_id=1>
	      ; END_STREAM | END_HEADERS
	      ; Open new stream
	      :authority: localhost:8443
	      :method: GET
	      :path: /
	      :scheme: https
	      accept: */*
	      accept-encoding: gzip, deflate
	      user-agent: nghttp2/0.1.0-DEV
    [  0.006] recv SETTINGS frame <length=16, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(4):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(7):65535]
    [  0.006] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.006] recv WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
	      (window_size_increment=1000000007)
    [  0.006] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.006] recv HEADERS frame <length=132, flags=0x04, stream_id=1>
	      ; END_HEADERS
	      ; First response header
	      :status: 200
	      accept-ranges: bytes
	      content-encoding: gzip
	      content-length: 146
	      content-type: text/html
	      date: Sun, 27 Oct 2013 14:23:54 GMT
	      etag: "b1-4e5535a027780-gzip"
	      last-modified: Sun, 01 Sep 2013 14:34:22 GMT
	      server: Apache/2.4.6 (Debian)
	      vary: Accept-Encoding
	      via: 1.1 nghttpx
    [  0.006] recv DATA frame <length=146, flags=0x00, stream_id=1>
    [  0.006] recv DATA frame <length=0, flags=0x01, stream_id=1>
	      ; END_STREAM
    [  0.007] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
	      (last_stream_id=0, error_code=NO_ERROR(0), opaque_data(0)=[])

The HTTP Upgrade is performed like this::

    $ src/nghttp -vnu http://localhost:8080
    [  0.000] HTTP Upgrade request
    GET / HTTP/1.1
    Host: localhost:8080
    Connection: Upgrade, HTTP2-Settings
    Upgrade: HTTP-draft-09/2.0
    HTTP2-Settings: AAAABAAAAGQAAAAHAAD__w
    Accept: */*
    User-Agent: nghttp2/0.1.0-DEV


    [  0.000] HTTP Upgrade response
    HTTP/1.1 101 Switching Protocols
    Connection: Upgrade
    Upgrade: HTTP-draft-09/2.0


    [  0.001] HTTP Upgrade success
    [  0.001] send SETTINGS frame <length=16, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(4):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(7):65535]
    [  0.001] recv SETTINGS frame <length=16, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(4):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(7):65535]
    [  0.001] recv WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
	      (window_size_increment=1000000007)
    [  0.001] recv HEADERS frame <length=121, flags=0x04, stream_id=1>
	      ; END_HEADERS
	      ; First response header
	      :status: 200
	      accept-ranges: bytes
	      content-length: 177
	      content-type: text/html
	      date: Sun, 27 Oct 2013 14:26:04 GMT
	      etag: "b1-4e5535a027780"
	      last-modified: Sun, 01 Sep 2013 14:34:22 GMT
	      server: Apache/2.4.6 (Debian)
	      vary: Accept-Encoding
	      via: 1.1 nghttpx
    [  0.001] recv DATA frame <length=177, flags=0x00, stream_id=1>
    [  0.001] recv DATA frame <length=0, flags=0x01, stream_id=1>
	      ; END_STREAM
    [  0.001] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [  0.001] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
	      (last_stream_id=0, error_code=NO_ERROR(0), opaque_data(0)=[])
    [  0.001] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)

nghttpd - server
++++++++++++++++

``nghttpd`` is static web server. It is single threaded and
multiplexes connections using non-blocking socket.

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

``nghttpd`` only accept the HTTP/2.0 connection via NPN/ALPN or direct
HTTP/2.0 connection. No HTTP Upgrade is supported.

``-p`` option allows users to configure server push.

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

    $ src/nghttpd --no-tls -v 8080
    IPv4: listen on port 8080
    IPv6: listen on port 8080
    [id=1] [  1.189] send SETTINGS frame <length=8, flags=0x00, stream_id=0>
	      (niv=1)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(4):100]
    [id=1] [  1.191] recv SETTINGS frame <length=16, flags=0x00, stream_id=0>
	      (niv=2)
	      [SETTINGS_MAX_CONCURRENT_STREAMS(4):100]
	      [SETTINGS_INITIAL_WINDOW_SIZE(7):65535]
    [id=1] [  1.191] recv HEADERS frame <length=47, flags=0x05, stream_id=1>
	      ; END_STREAM | END_HEADERS
	      ; Open new stream
	      :authority: localhost:8080
	      :method: GET
	      :path: /
	      :scheme: http
	      accept: */*
	      accept-encoding: gzip, deflate
	      user-agent: nghttp2/0.1.0-DEV
    [id=1] [  1.192] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [id=1] [  1.192] send HEADERS frame <length=70, flags=0x04, stream_id=1>
	      ; END_HEADERS
	      ; First response header
	      :status: 404
	      content-encoding: gzip
	      content-type: text/html; charset=UTF-8
	      date: Sun, 27 Oct 2013 14:27:53 GMT
	      server: nghttpd nghttp2/0.1.0-DEV
    [id=1] [  1.192] send DATA frame <length=117, flags=0x00, stream_id=1>
    [id=1] [  1.192] send DATA frame <length=0, flags=0x01, stream_id=1>
	      ; END_STREAM
    [id=1] [  1.192] stream_id=1 closed
    [id=1] [  1.192] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
	      ; ACK
	      (niv=0)
    [id=1] [  1.192] recv GOAWAY frame <length=8, flags=0x00, stream_id=0>
	      (last_stream_id=0, error_code=NO_ERROR(0), opaque_data(0)=[])
    [id=1] [  1.192] closed

nghttpx - proxy
+++++++++++++++

The ``nghttpx`` is a multi-threaded reverse proxy for
HTTP-draft-09/2.0, SPDY and HTTP/1.1. It has several operation modes:

================== ============================== ============== =============
Mode option        Frontend                       Backend        Note
================== ============================== ============== =============
default mode       HTTP/2.0, SPDY, HTTP/1.1 (TLS) HTTP/1.1       Reverse proxy
``--http2-proxy``  HTTP/2.0, SPDY, HTTP/1.1 (TLS) HTTP/1.1       SPDY proxy
``--http2-bridge`` HTTP/2.0, SPDY, HTTP/1.1 (TLS) HTTP/2.0 (TLS)
``--client``       HTTP/2.0, HTTP/1.1             HTTP/2.0 (TLS)
``--client-proxy`` HTTP/2.0, HTTP/1.1             HTTP/2.0 (TLS) Forward proxy
================== ============================== ============== =============

The interesting mode at the moment is the default mode. It works like
a reverse proxy and listens HTTP-draft-09/2.0, SPDY and HTTP/1.1 and
can be deployed SSL/TLS terminator for existing web server.

The default mode, ``--http2-proxy`` and ``--http2-bridge`` modes use
SSL/TLS in the frontend connection by default. To disable SSL/TLS, use
``--frontend-no-tls`` option. If that option is used, SPDY is disabled
in the frontend and incoming HTTP/1.1 connection can be upgraded to
HTTP/2.0 through HTTP Upgrade.

The ``--http2-bridge``, ``--client`` and ``--client-proxy`` modes use
SSL/TLS in the backend connection by deafult. To disable SSL/TLS, use
``--backend-no-tls`` option.

The ``nghttpx`` supports configuration file. See ``--conf`` option and
sample configuration file ``nghttpx.conf.sample``.

The ``nghttpx`` does not support server push.

In the default mode, (without any of ``--http2-proxy``,
``--http2-bridge``, ``--client-proxy`` and ``--client`` options),
``nghttpx`` works as reverse proxy to the backend server::

    Client <-- (HTTP/2.0, SPDY, HTTP/1.1) --> nghttpx <-- (HTTP/1.1) --> Web Server
                                          [reverse proxy]

With ``--http2-proxy`` option, it works as so called secure proxy (aka
SPDY proxy)::

    Client <-- (HTTP/2.0, SPDY, HTTP/1.1) --> nghttpx <-- (HTTP/1.1) --> Proxy
                                           [secure proxy]            (e.g., Squid)

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

At the time of this writing, Chrome is the only browser which supports
secure proxy. The one way to configure Chrome to use secure proxy is
create 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.  Please note that Chrome requires valid
certificate for secure proxy.

Then run chrome with the following arguments::

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

With ``--http2-bridge``, it accepts HTTP/2.0, SPDY and HTTP/1.1
connections and communicates with backend in HTTP/2.0::

    Client <-- (HTTP/2.0, SPDY, HTTP/1.1) --> nghttpx <-- (HTTP/2.0) --> Web or HTTP/2.0 Proxy etc
                                                                         (e.g., nghttpx -s)

With ``--client-proxy`` option, it works as forward proxy and expects
that the backend is HTTP/2.0 proxy::

    Client <-- (HTTP/2.0, HTTP/1.1) --> nghttpx <-- (HTTP/2.0) --> HTTP/2.0 Proxy
                                     [forward proxy]               (e.g., nghttpx -s)

The ``Client`` is needs to be configured to use nghttpx as forward
proxy.  The frontend HTTP/1.1 connection can be upgraded to HTTP/2.0
through HTTP Upgrade.  With the above configuration, one can use
HTTP/1.1 client to access and test their HTTP/2.0 servers.

With ``--client`` option, it works as reverse proxy and expects that
the backend is HTTP/2.0 Web server::

    Client <-- (HTTP/2.0, HTTP/1.1) --> nghttpx <-- (HTTP/2.0) --> Web Server
                                    [reverse proxy]

The frontend HTTP/1.1 connection can be upgraded to HTTP/2.0
through HTTP Upgrade.

For the operation modes which talk to the backend in HTTP/2.0 over
SSL/TLS, the backend connections can be tunneled though HTTP
proxy. The proxy is specified using ``--backend-http-proxy-uri``
option. The following figure illustrates the example of
``--http2-bridge`` and ``--backend-http-proxy-uri`` option to talk to
the outside HTTP/2.0 proxy through HTTP proxy::

    Client <-- (HTTP/2.0, SPDY, HTTP/1.1) --> nghttpx <-- (HTTP/2.0) --

            --===================---> HTTP/2.0 Proxy
              (HTTP proxy tunnel)     (e.g., nghttpx -s)

HPACK tools
-----------

The ``src`` directory contains HPACK tools. The ``deflatehd`` is
command-line header compression tool. The ``inflatehd`` is
command-line header decompression tool.  Both tools read input from
stdin and write output to stdout. The errors are written to
stderr. They take JSON as input and output.

deflatehd - header compressor
+++++++++++++++++++++++++++++

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

For the JSON input, the element of input array must be a JSON
object. Each object must have at least following key:

headers
    A JSON array of name/value pairs. The each element is a JSON array
    of 2 strings. The index 0 must contain header name and the index 1
    must contain header value.

Example::

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

These header sets are processed in the order they appear in the JSON
outer most array using same compression context.

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

Example::

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

    :method: POST
    user-agent: nghttp2

The output is a JSON array and each element is JSON object, which has
at least following keys:

seq
    The index of header set in the input.

inputLen
    The sum of length of name/value pair in the input.

outputLength
    The length of compressed header block.

percentageOfOriginalSize
    inputLen / outputLength * 100

output
    The compressed header block in hex string.

Examples::

    [
      {
        "seq": 0,
        "inputLen": 66,
        "outputLength": 20,
        "percentageOfOriginalSize": 30.303030303030305,
        "output": "818703881f3468e5891afcbf863c856659c62e3f"
      },
      {
        "seq": 1,
        "inputLen": 74,
        "outputLength": 10,
        "percentageOfOriginalSize": 13.513513513513514,
        "output": "87038504252dd5918386"
      }
    ]

The output can be used as the input for ``inflatehd``.

With ``-d`` option, the extra ``headerTable`` key is added and its
associated value contains the state of dyanmic header table after the
corresponding header set was processed. The value contains 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. They may be displayed as ``**DEALLOCATED**``,
    which means that the memory for that string is freed and not
    available. This will happen when the specifying smaller value in
    ``-S`` than ``-s``.

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

maxSize
    The maximum header table size.

deflateSize
    The sum of the spaces entries occupied within ``maxDeflateSize``.

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

Example::

    [
      {
	"seq": 0,
	"inputLen": 66,
	"outputLength": 20,
	"percentageOfOriginalSize": 30.303030303030305,
	"output": "818703881f3468e5891afcbf863c856659c62e3f",
	"headerTable": {
	  "entries": [
	    {
	      "index": 0,
	      "name": "user-agent",
	      "value": "nghttp2",
	      "referenced": true,
	      "size": 49
	    },
	    {
	      "index": 1,
	      "name": ":path",
	      "value": "/",
	      "referenced": true,
	      "size": 38
	    },
	    {
	      "index": 2,
	      "name": ":authority",
	      "value": "example.org",
	      "referenced": true,
	      "size": 53
	    },
	    {
	      "index": 3,
	      "name": ":scheme",
	      "value": "https",
	      "referenced": true,
	      "size": 44
	    },
	    {
	      "index": 4,
	      "name": ":method",
	      "value": "GET",
	      "referenced": true,
	      "size": 42
	    }
	  ],
	  "size": 226,
	  "maxSize": 4096,
	  "deflateSize": 226,
	  "maxDeflateSize": 4096
	}
      },
      {
	"seq": 1,
	"inputLen": 74,
	"outputLength": 10,
	"percentageOfOriginalSize": 13.513513513513514,
	"output": "87038504252dd5918386",
	"headerTable": {
	  "entries": [
	    {
	      "index": 0,
	      "name": ":path",
	      "value": "/account",
	      "referenced": true,
	      "size": 45
	    },
	    {
	      "index": 1,
	      "name": ":method",
	      "value": "POST",
	      "referenced": true,
	      "size": 43
	    },
	    {
	      "index": 2,
	      "name": "user-agent",
	      "value": "nghttp2",
	      "referenced": true,
	      "size": 49
	    },
	    {
	      "index": 3,
	      "name": ":path",
	      "value": "/",
	      "referenced": false,
	      "size": 38
	    },
	    {
	      "index": 4,
	      "name": ":authority",
	      "value": "example.org",
	      "referenced": true,
	      "size": 53
	    },
	    {
	      "index": 5,
	      "name": ":scheme",
	      "value": "https",
	      "referenced": true,
	      "size": 44
	    },
	    {
	      "index": 6,
	      "name": ":method",
	      "value": "GET",
	      "referenced": false,
	      "size": 42
	    }
	  ],
	  "size": 314,
	  "maxSize": 4096,
	  "deflateSize": 314,
	  "maxDeflateSize": 4096
	}
      }
    ]

inflatehd - header decompressor
+++++++++++++++++++++++++++++++

The ``inflatehd`` reads JSON array from stdin and outputs decompressed
name/value pairs in JSON array.  The element of input array must be a
JSON object. Each object must have at least following key:

output
    compressed header block in hex string.

Example::

    [
      { "output": "0284f77778ff" },
      { "output": "0185fafd3c3c7f81" }
    ]

The output is a JSON array and each element is JSON object, which has
at least following keys:

seq
    The index of header set in the input.

headers
    The JSON array contains decompressed name/value pairs. Each
    element is JSON aray having 2 elements. The index 0 of the array
    contains the header field name. The index 1 contains the header
    field value.

Example::

    [
      {
	"seq": 0,
	"headers": [
	  [":authority", "example.org"],
	  [":method", "GET"],
	  [":path", "/"],
	  [":scheme", "https"],
	  ["user-agent", "nghttp2"]
	]
      },
      {
	"seq": 1,
	"headers": [
	  [":authority", "example.org"],
	  [":method", "POST"],
	  [":path", "/account"],
	  [":scheme", "https"],
	  ["user-agent", "nghttp2"]
	]
      }
    ]

The output can be used as the input for ``deflatehd``.

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

Python bindings
---------------

This ``python`` directory contains nghttp2 Python bindings. The
bindings currently only provide HPACK compressor and decompressor
classes.

The extension module is called ``nghttp2``.

``make`` will build the bindings and target Python version is
determined by configure script. If the detected Python version is not
what you expect, specify a path to Python executable in ``PYTHON``
variable as an argument to configure script (e.g., ``./configure
PYTHON=/usr/bin/python3.3``).

Example
+++++++

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

    import binascii
    import nghttp2

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

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

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