grpc與http2的關系

grpc client 發送包到原生的http2 server

client收到報錯：

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

server端輸出：

輸出正常，包括了http2的所有信息，默認情況下響應了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

總結：

原生http2協議server端能夠完全解析grpc客戶端發送的請求，獲取任意請求信息。原生http2協議server默認響應不符合grpc客戶端標准。從grpc客戶端的響應來看，應該是content-type不對。

grpc客戶端自定義的固定頭信息： content-type: application/grpc user-agent: grpc-go/1.0 method: POST

也就是說，grpc規定了一些固定的特定的頭信息的值，這是與原生http2協議不一樣的。

http2 client 發送包到 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 發送與接收的信息：

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服務端自定義的固定頭信息： content-type: application/grpc grpc-status: 12 grpc-message: unknown service abc/efg

小結：

所以，默認的原生http2客戶端與grpc服務端只能夠實現通信，但也不能夠實現完整正確的響應解析。

總結

grpc與原生http2能夠實現協議通信，但在通信包的解釋上有更進一步的特殊處理，從而會導致並不能直接與原生http2協議愉快通信。

比如解釋content-type不能識別時，導致的連接異常主斷開，無法繼續后續的請求與響應。

nghttp 包幫助調試

啟動原生http2/h2c server端：

 nghttpd 5003 --no-tls

發送原生http2請求：

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

如何使用原生http2服務正確地接收並響應grpc請求

了解這個問題，以便在可能時候實現基於原生http2的grpc反向代理。