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frame.go
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frame.go
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package spdy
import (
"encoding/binary"
"fmt"
)
const (
flagSYN uint8 = iota // 握手信号
flagFIN // 结束信号
flagDAT // 发送数据
)
const (
sizeofFlag = 1
sizeofSid = 4
sizeofSize = 2
sizeofHeader = sizeofFlag + sizeofSid + sizeofSize
)
type frame struct {
flag uint8
sid uint32
data []byte
}
func (fm frame) pack() []byte {
dsz := len(fm.data)
dat := make([]byte, sizeofHeader+dsz)
dat[0] = fm.flag
binary.BigEndian.PutUint32(dat[sizeofFlag:], fm.sid)
binary.BigEndian.PutUint16(dat[sizeofFlag+sizeofSid:], uint16(dsz))
copy(dat[sizeofHeader:], fm.data)
return dat
}
type frameHeader [sizeofHeader]byte
func (fh frameHeader) flag() uint8 {
return fh[0]
}
func (fh frameHeader) streamID() uint32 {
return binary.BigEndian.Uint32(fh[sizeofFlag:])
}
func (fh frameHeader) size() uint16 {
return binary.BigEndian.Uint16(fh[sizeofFlag+sizeofSid:])
}
func (fh frameHeader) String() string {
flag := fh.flag()
sid := fh.streamID()
size := fh.size()
var str string
switch flag {
case flagSYN:
str = "SYN"
case flagFIN:
str = "FIN"
case flagDAT:
str = "DAT"
default:
str = "ERR"
}
return fmt.Sprintf("Frame Flag: %s, StreamID: %d, Datasize: %d", str, sid, size)
}