在Go中解码http2帧头/数据

Question

I am trying to read from a tcp connection which contains HTTP/2 data. Below is the code for reading HEADERS frame -

framer := http2.NewFramer(conn, conn)
frame, _ := framer.ReadFrame()

fmt.Printf("fh type: %s
", frame.Header().Type)
fmt.Printf("fh type: %d
", frame.Header().Type)
fmt.Printf("fh flag: %d
", frame.Header().Flags)
fmt.Printf("fh length: %d
", frame.Header().Length)
fmt.Printf("fh streamid: %d
", frame.Header().StreamID)
headersframe := (frame1.(*http2.HeadersFrame))
fmt.Printf("stream ended? %v
", headersframe.StreamEnded())
fmt.Printf("block fragment: %x
", headersframe.HeaderBlockFragment())        

I send request using curl as -

curl -v https://127.0.0.1:8000/ -k --http2

This is the output I get (after reading connection preface and SETTINGS), if I read from the conn using above code -

fh type: HEADERS
fh type: 1
fh flag: 5
fh length: 30
fh streamid: 1
stream ended? true
block fragment: 828487418a089d5c0b8170dc6c4d8b7a8825b650c3abb6f2e053032a2f2a

I understand the ouput, except the block fragment part and how to decode it into ascii string? I want to know the protocol/method/url path information.

Answer 1

I figured it out using Go hpack library (https://godoc.org/golang.org/x/net/http2/hpack) -

decoder := hpack.NewDecoder(2048, nil)
hf, _ := decoder.DecodeFull(headersframe.HeaderBlockFragment())
for _, h := range hf {
      fmt.Printf("%s
", h.Name + ":" + h.Value)
}

This prints -

:method:GET
:path:/
:scheme:https
:authority:127.0.0.1:5252
user-agent:curl/7.58.0
accept:*/*