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使用 nghttp2 调试 HTTP/2 流量

在本站之前的文章中，我介绍过两种查看 HTTP/2 流量的方法：1）在 Chrome 地址栏输入 chrome://net-internals/#http2 ，使用 Chrome 自带的 HTTP/2 调试工具；2）使用 Wireshark 调试 HTTP/2 流量。

方案 1 使用方便，但受限于 Chrome 浏览器，对于 Chrome 不支持的 h2c（HTTP/2 Cleartext，没有部署 TLS 的 HTTP/2）协议无能为力。同时，这个工具显示的信息经过了解析和筛选，不够全面。而在方案 2 中，Wireshark 位于服务端和浏览器之间，充当的是中间人角色，用它查看 HTTP/2 over HTTPS 流量时，必须拥有网站私钥或者借助浏览器共享对称密钥，才能解密 TLS 流量，配置起来比较麻烦。

而本文要介绍的 nghttp2 ，是一个用 C 实现的 HTTP/2 库，支持 h2c。它可以做为其它软件的一部分，为其提供 HTTP/2 相关功能（例如 curl 的 HTTP/2 功能就是用的 nghttp2）。除此之外，它还提供了四个有用的 HTTP/2 工具：

nghttp：HTTP/2 客户端；
nghttpd：HTTP/2 服务端；
nghttpx：HTTP/2 代理，提供 HTTP/1、HTTP/2 等协议之间的转换；
h2load：HTTP/2 性能测试工具；

本文简单介绍 nghttp、h2load 这两个工具。

nghttp2 官方文档中有详细的编译依赖说明。对于我一直在用的 Ubuntu 14.04 LTS 来说，安装依赖是一件再简单不过的事情：

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 libjemalloc-dev cython python3-dev python-setuptools

解决依赖问题后，获取源码并编译安装即可：

git clone https://github.com/tatsuhiro-t/nghttp2.git  cd ./nghttp2  autoreconf -i automake autoconf ./configure  make sudo make install

一切妥当后，nghttp2 提供的几个工具就可以直接用了。

nghttp 做为一个功能完整的 HTTP/2 客户端，非常适合用来查看和调试 HTTP/2 流量。它支持的参数很多，通过官方文档或者 nghttp -h 都能查看。最常用几个参数如下：

-v, --verbose，输出完整的 debug 信息；
-n, --null-out，丢弃下载的数据；
-a, --get-assets，下载 html 中的 css、js、image 等外链资源；
-H, --header=<HEADER>，添加请求头部字段，如 -H':method: PUT' ；
-u, --upgrade，使用 HTTP 的 Upgrade 机制来协商 HTTP/2 协议，用于 h2c，详见下面的例子；

以下是使用 nghttp 访问 nghttp2 官网的结果。从调试信息中可以清晰看到 h2c 协商以及 Server Push 的整个过程：

nghttp -nvu http://nghttp2.org  [  0.147] Connected [  0.147] HTTP Upgrade request GET / HTTP/1.1 host: nghttp2.org connection: Upgrade, HTTP2-Settings upgrade: h2c http2-settings: AAMAAABkAAQAAP__ accept: */* user-agent: nghttp2/1.9.0-DEV  [  0.291] HTTP Upgrade response HTTP/1.1 101 Switching Protocols Connection: Upgrade Upgrade: h2c  [  0.291] HTTP Upgrade success [  0.291] recv SETTINGS frame <length=12, flags=0x00, stream_id=0>           (niv=2)           [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]           [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535] [  0.291] send SETTINGS frame <length=12, flags=0x00, stream_id=0>           (niv=2)           [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]           [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535] [  0.291] send SETTINGS frame <length=0, flags=0x01, stream_id=0>           ; ACK           (niv=0) [  0.291] send PRIORITY frame <length=5, flags=0x00, stream_id=3>           (dep_stream_id=0, weight=201, exclusive=0) [  0.291] send PRIORITY frame <length=5, flags=0x00, stream_id=5>           (dep_stream_id=0, weight=101, exclusive=0) [  0.291] send PRIORITY frame <length=5, flags=0x00, stream_id=7>           (dep_stream_id=0, weight=1, exclusive=0) [  0.291] send PRIORITY frame <length=5, flags=0x00, stream_id=9>           (dep_stream_id=7, weight=1, exclusive=0) [  0.291] send PRIORITY frame <length=5, flags=0x00, stream_id=11>           (dep_stream_id=3, weight=1, exclusive=0) [  0.291] send PRIORITY frame <length=5, flags=0x00, stream_id=1>           (dep_stream_id=11, weight=16, exclusive=0) [  0.291] recv (stream_id=1) :method: GET [  0.291] recv (stream_id=1) :scheme: http [  0.291] recv (stream_id=1) :path: /stylesheets/screen.css [  0.291] recv (stream_id=1) :authority: nghttp2.org [  0.291] recv (stream_id=1) host: nghttp2.org [  0.291] recv (stream_id=1) user-agent: nghttp2/1.9.0-DEV [  0.291] recv PUSH_PROMISE frame <length=59, flags=0x04, stream_id=1>           ; END_HEADERS           (padlen=0, promised_stream_id=2) [  0.291] recv (stream_id=1) :status: 200 [  0.291] recv (stream_id=1) date: Mon, 07 Mar 2016 13:02:35 GMT [  0.291] recv (stream_id=1) content-type: text/html [  0.291] recv (stream_id=1) content-length: 6654 [  0.291] recv (stream_id=1) last-modified: Mon, 29 Feb 2016 15:38:08 GMT [  0.291] recv (stream_id=1) etag: "56d465e0-19fe" [  0.291] recv (stream_id=1) link: </stylesheets/screen.css>; rel=preload; as=stylesheet [  0.291] recv (stream_id=1) accept-ranges: bytes [  0.291] recv (stream_id=1) x-backend-header-rtt: 0.00093 [  0.291] recv (stream_id=1) server: nghttpx nghttp2/1.9.0-DEV [  0.291] recv (stream_id=1) via: 2 nghttpx [  0.291] recv (stream_id=1) x-frame-options: SAMEORIGIN [  0.291] recv (stream_id=1) x-xss-protection: 1; mode=block [  0.291] recv (stream_id=1) x-content-type-options: nosniff [  0.291] recv HEADERS frame <length=251, flags=0x04, stream_id=1>           ; END_HEADERS           (padlen=0)           ; First response header [  0.471] recv DATA frame <length=6654, flags=0x01, stream_id=1>           ; END_STREAM [  0.471] recv (stream_id=2) :status: 200 [  0.471] recv (stream_id=2) date: Mon, 07 Mar 2016 13:02:35 GMT [  0.471] recv (stream_id=2) content-type: text/css [  0.471] recv (stream_id=2) content-length: 39082 [  0.471] recv (stream_id=2) last-modified: Mon, 29 Feb 2016 15:38:08 GMT [  0.471] recv (stream_id=2) etag: "56d465e0-98aa" [  0.471] recv (stream_id=2) accept-ranges: bytes [  0.471] recv (stream_id=2) x-backend-header-rtt: 0.000479 [  0.471] recv (stream_id=2) server: nghttpx nghttp2/1.9.0-DEV [  0.471] recv (stream_id=2) via: 2 nghttpx [  0.471] recv (stream_id=2) x-frame-options: SAMEORIGIN [  0.471] recv (stream_id=2) x-xss-protection: 1; mode=block [  0.471] recv (stream_id=2) x-content-type-options: nosniff [  0.471] recv (stream_id=2) x-http2-push: 1 [  0.471] recv HEADERS frame <length=61, flags=0x04, stream_id=2>           ; END_HEADERS           (padlen=0)           ; First push response header [  0.964] recv DATA frame <length=16384, flags=0x00, stream_id=2> [  0.964] recv DATA frame <length=16384, flags=0x00, stream_id=2> [  0.964] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>           (window_size_increment=37620) [  0.964] send WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=2>           (window_size_increment=32768) [  1.538] recv DATA frame <length=6314, flags=0x01, stream_id=2>           ; END_STREAM [  1.538] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>           ; ACK           (niv=0) [  1.538] send GOAWAY frame <length=8, flags=0x00, stream_id=0>           (last_stream_id=2, error_code=NO_ERROR(0x00), opaque_data(0)=[])

h2load 是一个支持 HTTP/2 的压测工具，可以用来测试 HTTP/2 服务的稳定性、QPS 等信息。它支持的参数也可以通过官网文档或者 h2load -h 来查看。下面是一个简单例子：

h2load https://example.com -n 100 -c 10  starting benchmark... spawning thread #0: 10 total client(s). 100 total requests TLS Protocol: TLSv1.2 Cipher: ECDHE-RSA-AES128-GCM-SHA256 Application protocol: h2 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 589.98ms, 169.50 req/s, 2.19MB/s requests: 100 total, 100 started, 100 done, 100 succeeded, 0 failed, 0 errored, 0 timeout status codes: 100 2xx, 0 3xx, 0 4xx, 0 5xx traffic: 1.29MB (1353790) total, 53.42KB (54700) headers (space savings 24.97%), 1.24MB (1295000) data                      min         max         mean         sd        +/- sd time for request:    17.63ms     73.47ms     32.06ms     10.24ms    78.00% time for connect:    81.84ms    168.23ms    119.76ms     26.44ms    60.00% time to 1st byte:   119.09ms    201.01ms    158.06ms     23.86ms    70.00% req/s           :      17.00       28.63       23.12        3.20    60.00%