well-goknown/vendor/github.com/gobwas/ws/write.go

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package ws
import (
"encoding/binary"
"io"
)
// Header size length bounds in bytes.
const (
MaxHeaderSize = 14
MinHeaderSize = 2
)
const (
bit0 = 0x80
bit1 = 0x40
bit2 = 0x20
bit3 = 0x10
bit4 = 0x08
bit5 = 0x04
bit6 = 0x02
bit7 = 0x01
len7 = int64(125)
len16 = int64(^(uint16(0)))
len64 = int64(^(uint64(0)) >> 1)
)
// HeaderSize returns number of bytes that are needed to encode given header.
// It returns -1 if header is malformed.
func HeaderSize(h Header) (n int) {
switch {
case h.Length < 126:
n = 2
case h.Length <= len16:
n = 4
case h.Length <= len64:
n = 10
default:
return -1
}
if h.Masked {
n += len(h.Mask)
}
return n
}
// WriteHeader writes header binary representation into w.
func WriteHeader(w io.Writer, h Header) error {
// Make slice of bytes with capacity 14 that could hold any header.
bts := make([]byte, MaxHeaderSize)
if h.Fin {
bts[0] |= bit0
}
bts[0] |= h.Rsv << 4
bts[0] |= byte(h.OpCode)
var n int
switch {
case h.Length <= len7:
bts[1] = byte(h.Length)
n = 2
case h.Length <= len16:
bts[1] = 126
binary.BigEndian.PutUint16(bts[2:4], uint16(h.Length))
n = 4
case h.Length <= len64:
bts[1] = 127
binary.BigEndian.PutUint64(bts[2:10], uint64(h.Length))
n = 10
default:
return ErrHeaderLengthUnexpected
}
if h.Masked {
bts[1] |= bit0
n += copy(bts[n:], h.Mask[:])
}
_, err := w.Write(bts[:n])
return err
}
// WriteFrame writes frame binary representation into w.
func WriteFrame(w io.Writer, f Frame) error {
err := WriteHeader(w, f.Header)
if err != nil {
return err
}
_, err = w.Write(f.Payload)
return err
}
// MustWriteFrame is like WriteFrame but panics if frame can not be read.
func MustWriteFrame(w io.Writer, f Frame) {
if err := WriteFrame(w, f); err != nil {
panic(err)
}
}