nghttp2 - HTTP/2 C Library

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

The framing layer of HTTP/2 is implemented as form of reusable C library. On top of that, we have implemented HTTP/2 client, server and proxy. Also we have developed load test/benchmarking tool for HTTP/2 and SPDY.

HPACK encoding and decoding are available as public API.

We have Python binding of this libary, but we have not covered everything yet.

Development Status

We started to implement h2-13 (http://tools.ietf.org/html/draft-ietf-httpbis-http2-13) and the header compression (http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08).

The nghttp2 code base was forked from spdylay project.

HTTP/2 Features Support
Core frames handling Yes
Dependency Tree Yes
Large header (CONTINUATION) Yes
ALTSVC extension Yes *1
  • *1 As described in draft-12, but reserved byte was removed. ALTSVC may be removed from nghttp2 public API since it is not stabilized yet.

BLOCKED frame, which once existed in h2-12, was removed in h2-13.

Public Test Server

The following endpoints are available to try out nghttp2 implementation.

  • https://nghttp2.org/ (TLS + NPN)

    NPN offer h2-13, spdy/3.1 and http/1.1. ALPN is currently disabled.

    This endpoint requires TLSv1.2 and DHE or EDCHE with GCM cipher suite for HTTP/2 connection.

  • http://nghttp2.org/ (Upgrade / Direct)

    h2c-13 and http/1.1. We configured this server to send ALTSVC frame or Alt-Svc header field to announce that alternative service is available at port 443.

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:

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
  • zlib >= 1.2.3

ALPN support requires unreleased version OpenSSL >= 1.0.2.

To enable SPDY protocol in the application program nghttpx and h2load, the following package is required:

  • spdylay >= 1.2.3

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

  • libxml2 >= 2.7.7

The HPACK tools require the following package:

  • jansson >= 2.5

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

  • jemalloc

The Python bindings require the following packages:

  • cython >= 0.19
  • python >= 2.7

If you are using Ubuntu 14.04 LTS, 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
  • libjemalloc-dev
  • cython
  • python3.4-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

To compile source code, gcc >= 4.8.3 or clang >= 3.4 is required.

Note

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

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 https://nghttp2.org/documentation/

Client, Server and Proxy programs

The src directory contains 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:

$ src/nghttp -nv https://nghttp2.org
[  0.033][NPN] server offers:
          * h2-13
          * spdy/3.1
          * http/1.1
The negotiated protocol: h2-13
[  0.068] send SETTINGS frame <length=15, flags=0x00, stream_id=0>
          (niv=3)
          [SETTINGS_MAX_CONCURRENT_STREAMS(3):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(4):65535]
          [SETTINGS_COMPRESS_DATA(5):1]
[  0.068] send HEADERS frame <length=46, flags=0x05, stream_id=1>
          ; END_STREAM | END_HEADERS
          (padlen=0)
          ; Open new stream
          :authority: nghttp2.org
          :method: GET
          :path: /
          :scheme: https
          accept: */*
          accept-encoding: gzip, deflate
          user-agent: nghttp2/0.4.0-DEV
[  0.068] recv SETTINGS frame <length=10, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(3):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(4):65535]
[  0.068] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.079] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.080] (stream_id=1, noind=0) :status: 200
[  0.080] (stream_id=1, noind=0) accept-ranges: bytes
[  0.080] (stream_id=1, noind=0) age: 15
[  0.080] (stream_id=1, noind=0) content-length: 40243
[  0.080] (stream_id=1, noind=0) content-type: text/html
[  0.080] (stream_id=1, noind=0) date: Wed, 14 May 2014 15:14:30 GMT
[  0.080] (stream_id=1, noind=0) etag: "535d0eea-9d33"
[  0.080] (stream_id=1, noind=0) last-modified: Sun, 27 Apr 2014 14:06:34 GMT
[  0.080] (stream_id=1, noind=0) server: nginx/1.4.6 (Ubuntu)
[  0.080] (stream_id=1, noind=0) x-varnish: 2114900538 2114900537
[  0.080] (stream_id=1, noind=0) via: 1.1 varnish, 1.1 nghttpx
[  0.080] (stream_id=1, noind=0) strict-transport-security: max-age=31536000
[  0.080] recv HEADERS frame <length=162, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0)
          ; First response header
[  0.080] recv DATA frame <length=3786, flags=0x00, stream_id=1>
[  0.080] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.081] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.093] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.093] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.094] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.094] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.094] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.096] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.096] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
          (window_size_increment=36554)
[  0.096] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=1>
          (window_size_increment=36554)
[  0.108] recv DATA frame <length=3689, flags=0x00, stream_id=1>
[  0.108] recv DATA frame <length=0, flags=0x01, stream_id=1>
          ; END_STREAM
[  0.108] 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 -nvu http://nghttp2.org
[  0.013] HTTP Upgrade request
GET / HTTP/1.1
Host: nghttp2.org
Connection: Upgrade, HTTP2-Settings
Upgrade: h2c-13
HTTP2-Settings: AwAAAGQEAAD__wUAAAAB
Accept: */*
User-Agent: nghttp2/0.4.0-DEV


[  0.024] HTTP Upgrade response
HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Upgrade: h2c-13


[  0.024] HTTP Upgrade success
[  0.024] send SETTINGS frame <length=15, flags=0x00, stream_id=0>
          (niv=3)
          [SETTINGS_MAX_CONCURRENT_STREAMS(3):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(4):65535]
          [SETTINGS_COMPRESS_DATA(5):1]
[  0.024] recv SETTINGS frame <length=10, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(3):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(4):65535]
[  0.024] recv ALTSVC frame <length=43, flags=0x00, stream_id=0>
          (max-age=86400, port=443, protocol_id=h2-13, host=nghttp2.org, origin=http://nghttp2.org)
[  0.024] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.024] (stream_id=1, noind=0) :status: 200
[  0.024] (stream_id=1, noind=0) accept-ranges: bytes
[  0.024] (stream_id=1, noind=0) age: 10
[  0.024] (stream_id=1, noind=0) content-length: 40243
[  0.024] (stream_id=1, noind=0) content-type: text/html
[  0.024] (stream_id=1, noind=0) date: Wed, 14 May 2014 15:16:34 GMT
[  0.024] (stream_id=1, noind=0) etag: "535d0eea-9d33"
[  0.024] (stream_id=1, noind=0) last-modified: Sun, 27 Apr 2014 14:06:34 GMT
[  0.024] (stream_id=1, noind=0) server: nginx/1.4.6 (Ubuntu)
[  0.024] (stream_id=1, noind=0) x-varnish: 2114900541 2114900540
[  0.024] (stream_id=1, noind=0) via: 1.1 varnish, 1.1 nghttpx
[  0.024] recv HEADERS frame <length=148, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0)
          ; First response header
[  0.024] recv DATA frame <length=3786, flags=0x00, stream_id=1>
[  0.025] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.031] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.031] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.032] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.032] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.033] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.033] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.033] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
          (window_size_increment=33164)
[  0.033] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=1>
          (window_size_increment=33164)
[  0.038] recv DATA frame <length=4096, flags=0x00, stream_id=1>
[  0.038] recv DATA frame <length=3689, flags=0x00, stream_id=1>
[  0.038] recv DATA frame <length=0, flags=0x01, stream_id=1>
          ; END_STREAM
[  0.038] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.038] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
          (last_stream_id=0, error_code=NO_ERROR(0), opaque_data(0)=[])

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 the HTTP/2 connection via NPN/ALPN or direct HTTP/2 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] [ 15.921] send SETTINGS frame <length=10, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(3):100]
          [SETTINGS_COMPRESS_DATA(5):1]
[id=1] [ 15.921] recv SETTINGS frame <length=15, flags=0x00, stream_id=0>
          (niv=3)
          [SETTINGS_MAX_CONCURRENT_STREAMS(3):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(4):65535]
          [SETTINGS_COMPRESS_DATA(5):1]
[id=1] [ 15.921] (stream_id=1, noind=0) :authority: localhost:8080
[id=1] [ 15.921] (stream_id=1, noind=0) :method: GET
[id=1] [ 15.921] (stream_id=1, noind=0) :path: /
[id=1] [ 15.921] (stream_id=1, noind=0) :scheme: http
[id=1] [ 15.921] (stream_id=1, noind=0) accept: */*
[id=1] [ 15.921] (stream_id=1, noind=0) accept-encoding: gzip, deflate
[id=1] [ 15.921] (stream_id=1, noind=0) user-agent: nghttp2/0.4.0-DEV
[id=1] [ 15.921] recv HEADERS frame <length=48, flags=0x05, stream_id=1>
          ; END_STREAM | END_HEADERS
          (padlen=0)
          ; Open new stream
[id=1] [ 15.921] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[id=1] [ 15.921] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[id=1] [ 15.921] send HEADERS frame <length=82, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0)
          ; First response header
          :status: 200
          cache-control: max-age=3600
          content-length: 612
          date: Wed, 14 May 2014 15:19:03 GMT
          last-modified: Sat, 08 Mar 2014 16:04:06 GMT
          server: nghttpd nghttp2/0.4.0-DEV
[id=1] [ 15.922] send DATA frame <length=381, flags=0x20, stream_id=1>
          ; COMPRESSED
[id=1] [ 15.922] send DATA frame <length=0, flags=0x01, stream_id=1>
          ; END_STREAM
[id=1] [ 15.922] stream_id=1 closed
[id=1] [ 15.922] recv GOAWAY frame <length=8, flags=0x00, stream_id=0>
          (last_stream_id=0, error_code=NO_ERROR(0), opaque_data(0)=[])
[id=1] [ 15.922] closed

nghttpx - proxy

nghttpx is a multi-threaded reverse proxy for h2-13, SPDY and HTTP/1.1 and powers nghttp2.org site. It has several operation modes:

Mode option Frontend Backend Note
default mode HTTP/2, SPDY, HTTP/1.1 (TLS) HTTP/1.1 Reverse proxy
--http2-proxy HTTP/2, SPDY, HTTP/1.1 (TLS) HTTP/1.1 SPDY proxy
--http2-bridge HTTP/2, SPDY, HTTP/1.1 (TLS) HTTP/2 (TLS)  
--client HTTP/2, HTTP/1.1 HTTP/2 (TLS)  
--client-proxy HTTP/2, HTTP/1.1 HTTP/2 (TLS) Forward proxy

The interesting mode at the moment is the default mode. It works like a reverse proxy and listens for h2-13, 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 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.

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

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

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, SPDY and HTTP/1.1 connections and communicates with backend in HTTP/2:

Client <-- (HTTP/2, SPDY, HTTP/1.1) --> nghttpx <-- (HTTP/2) --> Web or HTTP/2 Proxy etc
                                                                     (e.g., nghttpx -s)

With --client-proxy option, it works as forward proxy and expects that the backend is HTTP/2 proxy:

Client <-- (HTTP/2, HTTP/1.1) --> nghttpx <-- (HTTP/2) --> HTTP/2 Proxy
                                 [forward proxy]               (e.g., nghttpx -s)

The Client needs to be configured to use nghttpx as forward proxy. The frontend HTTP/1.1 connection can be upgraded to HTTP/2 through HTTP Upgrade. With the above configuration, one can use HTTP/1.1 client to access and test their HTTP/2 servers.

With --client option, it works as reverse proxy and expects that the backend is HTTP/2 Web server:

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

The frontend HTTP/1.1 connection can be upgraded to HTTP/2 through HTTP Upgrade.

For the operation modes which talk to the backend in HTTP/2 over SSL/TLS, the backend connections can be tunneled through 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 options to talk to the outside HTTP/2 proxy through HTTP proxy:

Client <-- (HTTP/2, SPDY, 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 and SPDY. The SPDY support is enabled if the program was built with spdylay library. The UI of h2load is heavily inspired by weighttp (https://github.com/lighttpd/weighttp). The typical usage is as follows:

$ src/h2load -n1000 -c10 -m10 https://127.0.0.1:8443/
starting benchmark...
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 0 sec, 152 millisec and 152 microsec, 6572 req/s, 749 kbytes/s
requests: 1000 total, 1000 started, 1000 done, 0 succeeded, 1000 failed, 0 errored
status codes: 0 2xx, 0 3xx, 1000 4xx, 0 5xx
traffic: 141100 bytes total, 840 bytes headers, 116000 bytes data

The above example issued total 1000 requests, using 10 concurrent clients (thus 10 HTTP/2 sessions), and maximum 10 streams per client. With -t option, h2load will use multiple native threads to avoid saturating single core on client side.

Warning

Don’t use this tool against publicly available servers. That is considered a DOS attack. Please only use against your private servers.

HPACK tools

The src directory contains HPACK tools. The deflatehd is a 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. We use (mostly) same JSON data format described at https://github.com/http2jp/hpack-test-case

deflatehd - header compressor

The deflatehd 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 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 headers key. Its value is an array of a JSON object, which includes exactly one name/value pair.

Example:

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

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

seq
The index of header set in the input.
input_length
The sum of length of name/value pair in the input.
output_length
The length of compressed header block.
percentage_of_original_size
input_length / output_length * 100
wire
The compressed header block in hex string.
headers
The input header set.
header_table_size
The header table size adjusted before deflating 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 -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 encoder uses. This can be smaller than max_size. In this case, 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 ouside 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 reads JSON data from stdin and outputs decompressed name/value pairs in JSON.

The root JSON object must include cases key. Its value has to include the sequence of compressed header block. 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 wire key. Its value is a compressed header block in hex string.

Example:

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

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

seq
The index of header set in the input.
headers
The JSON array includes decompressed name/value pairs.
wire
The compressed header block in 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 -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 format is the same as deflatehd.

Python bindings

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

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/python3.4).

The following example code illustrates basic usage of 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 request header fields, has arrived.

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

When whole request is received, on_request_done() is invoked.

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

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

The application can push resource using push() method. It must be used before 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 python

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()