grpc与http2的关系

https://nullget.sourceforge.io/?q=node/895

grpc与http2的关系

grpc client 发送包到原生的http2 server

client收到报错：

panic: rpc error: code = 9 desc = transport: received the unexpected content-type "text/html; charset=UTF-8"

server端输出：

输出正常，包括了http2的所有信息，默认情况下响应了404。

[id=1] [  3.994] send SETTINGS frame <length=6, flags=0x00, stream_id=0>
          (niv=1)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
[id=1] [  3.994] recv SETTINGS frame <length=0, flags=0x00, stream_id=0>
          (niv=0)
[id=1] [  3.994] recv WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
          (window_size_increment=983025)
[id=1] [  3.995] recv (stream_id=1) :method: POST
[id=1] [  3.995] recv (stream_id=1) :scheme: http
[id=1] [  3.995] recv (stream_id=1) :path: /flyrun.FlyRun/Run
[id=1] [  3.995] recv (stream_id=1) :authority: 127.0.0.1
[id=1] [  3.995] recv (stream_id=1) content-type: application/grpc
[id=1] [  3.995] recv (stream_id=1) user-agent: grpc-go/1.0
[id=1] [  3.995] recv (stream_id=1) te: trailers
[id=1] [  3.995] recv HEADERS frame <length=62, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0)
          ; Open new stream
[id=1] [  3.995] recv DATA frame <length=52, flags=0x01, stream_id=1>
          ; END_STREAM
[id=1] [  3.995] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[id=1] [  3.995] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[id=1] [  3.995] send HEADERS frame <length=69, flags=0x04, stream_id=1>
          ; END_HEADERS
          (padlen=0)
          ; First response header
          :status: 404
          server: nghttpd nghttp2/1.19.0
          date: Fri, 10 Feb 2017 07:17:14 GMT
          content-type: text/html; charset=UTF-8
          content-length: 147
[id=1] [  3.995] send DATA frame <length=147, flags=0x01, stream_id=1>
          ; END_STREAM
[id=1] [  3.995] stream_id=1 closed
[id=1] [  4.001] closed

总结：

原生http2协议server端能够完全解析grpc客户端发送的请求，获取任意请求信息。 原生http2协议server默认响应不符合grpc客户端标准。 从grpc客户端的响应来看，应该是content-type不对。

grpc客户端自定义的固定头信息： content-type: application/grpc user-agent: grpc-go/1.0 method: POST

也就是说，grpc规定了一些固定的特定的头信息的值，这是与原生http2协议不一样的。

http2 client 发送包到 grpc server

grpc server收到的信息：

2017/02/10 15:46:58 transport: http2Server.HandleStreams found unhandled frame type [FrameHeader PRIORITY stream=3 len=5].
 2017/02/10 15:46:58 transport: http2Server.HandleStreams found unhandled frame type [FrameHeader PRIORITY stream=5 len=5].
 2017/02/10 15:46:58 transport: http2Server.HandleStreams found unhandled frame type [FrameHeader PRIORITY stream=7 len=5].
 2017/02/10 15:46:58 transport: http2Server.HandleStreams found unhandled frame type [FrameHeader PRIORITY stream=9 len=5].
 2017/02/10 15:46:58 transport: http2Server.HandleStreams found unhandled frame type [FrameHeader PRIORITY stream=11 len=5].

原生 http2 发送与接收的信息：

nghttp -v http://127.0.0.1:5000/abc/efg/hehe                                                 [15/412]
[  0.000] Connected
[  0.000] send SETTINGS frame <length=12, flags=0x00, stream_id=0>
          (niv=2)
          [SETTINGS_MAX_CONCURRENT_STREAMS(0x03):100]
          [SETTINGS_INITIAL_WINDOW_SIZE(0x04):65535]
[  0.000] send PRIORITY frame <length=5, flags=0x00, stream_id=3>
          (dep_stream_id=0, weight=201, exclusive=0)
[  0.000] send PRIORITY frame <length=5, flags=0x00, stream_id=5>
          (dep_stream_id=0, weight=101, exclusive=0)
[  0.000] send PRIORITY frame <length=5, flags=0x00, stream_id=7>
          (dep_stream_id=0, weight=1, exclusive=0)
[  0.000] send PRIORITY frame <length=5, flags=0x00, stream_id=9>
          (dep_stream_id=7, weight=1, exclusive=0)
[  0.000] send PRIORITY frame <length=5, flags=0x00, stream_id=11>
          (dep_stream_id=3, weight=1, exclusive=0)
[  0.000] send HEADERS frame <length=49, 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: /abc/efg/hehe
          :scheme: http
          :authority: 127.0.0.1:5000
          accept: */*
          accept-encoding: gzip, deflate
          user-agent: nghttp2/1.19.0
[  0.000] recv SETTINGS frame <length=0, flags=0x00, stream_id=0>
          (niv=0)
[  0.000] recv WINDOW_UPDATE frame <length=4, flags=0x00, stream_id=0>
          (window_size_increment=983025)
[  0.000] send SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.000] recv (stream_id=13) :status: 200
[  0.000] recv (stream_id=13) content-type: application/grpc
[  0.000] recv (stream_id=13) grpc-status: 12
[  0.000] recv (stream_id=13) grpc-message: unknown service abc/efg
[  0.000] recv HEADERS frame <length=56, flags=0x05, stream_id=13>
          ; END_STREAM | END_HEADERS
          (padlen=0)
          ; First response header
[  0.000] recv SETTINGS frame <length=0, flags=0x01, stream_id=0>
          ; ACK
          (niv=0)
[  0.000] send GOAWAY frame <length=8, flags=0x00, stream_id=0>
          (last_stream_id=0, error_code=NO_ERROR(0x00), opaque_data(0)=[])

grpc服务端自定义的固定头信息： content-type: application/grpc grpc-status: 12 grpc-message: unknown service abc/efg

小结：

所以，默认的原生http2客户端与grpc服务端只能够实现通信，但也不能够实现完整正确的响应解析。

总结

grpc与原生http2能够实现协议通信，但在通信包的解释上有更进一步的特殊处理，从而会导致并不能直接与原生http2协议愉快通信。

比如解释content-type不能识别时，导致的连接异常主断开，无法继续后续的请求与响应。

nghttp 包 帮助调试

启动原生http2/h2c server端：

 nghttpd 5003 --no-tls

发送原生http2请求：

 nghttp -v http://127.0.0.1:5000/abc/efg/hehe

如何使用原生http2服务正确地接收并响应grpc请求

了解这个问题，以便在可能时候实现基于原生http2的grpc反向代理。