148 lines
3.6 KiB
Go
148 lines
3.6 KiB
Go
package ws
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"fmt"
|
|
"io"
|
|
)
|
|
|
|
// Errors used by frame reader.
|
|
var (
|
|
ErrHeaderLengthMSB = fmt.Errorf("header error: the most significant bit must be 0")
|
|
ErrHeaderLengthUnexpected = fmt.Errorf("header error: unexpected payload length bits")
|
|
)
|
|
|
|
// ReadHeader reads a frame header from r.
|
|
func ReadHeader(r io.Reader) (h Header, err error) {
|
|
// Make slice of bytes with capacity 12 that could hold any header.
|
|
//
|
|
// The maximum header size is 14, but due to the 2 hop reads,
|
|
// after first hop that reads first 2 constant bytes, we could reuse 2 bytes.
|
|
// So 14 - 2 = 12.
|
|
bts := make([]byte, 2, MaxHeaderSize-2)
|
|
|
|
// Prepare to hold first 2 bytes to choose size of next read.
|
|
_, err = io.ReadFull(r, bts)
|
|
if err != nil {
|
|
return h, err
|
|
}
|
|
|
|
h.Fin = bts[0]&bit0 != 0
|
|
h.Rsv = (bts[0] & 0x70) >> 4
|
|
h.OpCode = OpCode(bts[0] & 0x0f)
|
|
|
|
var extra int
|
|
|
|
if bts[1]&bit0 != 0 {
|
|
h.Masked = true
|
|
extra += 4
|
|
}
|
|
|
|
length := bts[1] & 0x7f
|
|
switch {
|
|
case length < 126:
|
|
h.Length = int64(length)
|
|
|
|
case length == 126:
|
|
extra += 2
|
|
|
|
case length == 127:
|
|
extra += 8
|
|
|
|
default:
|
|
err = ErrHeaderLengthUnexpected
|
|
return h, err
|
|
}
|
|
|
|
if extra == 0 {
|
|
return h, err
|
|
}
|
|
|
|
// Increase len of bts to extra bytes need to read.
|
|
// Overwrite first 2 bytes that was read before.
|
|
bts = bts[:extra]
|
|
_, err = io.ReadFull(r, bts)
|
|
if err != nil {
|
|
return h, err
|
|
}
|
|
|
|
switch {
|
|
case length == 126:
|
|
h.Length = int64(binary.BigEndian.Uint16(bts[:2]))
|
|
bts = bts[2:]
|
|
|
|
case length == 127:
|
|
if bts[0]&0x80 != 0 {
|
|
err = ErrHeaderLengthMSB
|
|
return h, err
|
|
}
|
|
h.Length = int64(binary.BigEndian.Uint64(bts[:8]))
|
|
bts = bts[8:]
|
|
}
|
|
|
|
if h.Masked {
|
|
copy(h.Mask[:], bts)
|
|
}
|
|
|
|
return h, nil
|
|
}
|
|
|
|
// ReadFrame reads a frame from r.
|
|
// It is not designed for high optimized use case cause it makes allocation
|
|
// for frame.Header.Length size inside to read frame payload into.
|
|
//
|
|
// Note that ReadFrame does not unmask payload.
|
|
func ReadFrame(r io.Reader) (f Frame, err error) {
|
|
f.Header, err = ReadHeader(r)
|
|
if err != nil {
|
|
return f, err
|
|
}
|
|
|
|
if f.Header.Length > 0 {
|
|
// int(f.Header.Length) is safe here cause we have
|
|
// checked it for overflow above in ReadHeader.
|
|
f.Payload = make([]byte, int(f.Header.Length))
|
|
_, err = io.ReadFull(r, f.Payload)
|
|
}
|
|
|
|
return f, err
|
|
}
|
|
|
|
// MustReadFrame is like ReadFrame but panics if frame can not be read.
|
|
func MustReadFrame(r io.Reader) Frame {
|
|
f, err := ReadFrame(r)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
return f
|
|
}
|
|
|
|
// ParseCloseFrameData parses close frame status code and closure reason if any provided.
|
|
// If there is no status code in the payload
|
|
// the empty status code is returned (code.Empty()) with empty string as a reason.
|
|
func ParseCloseFrameData(payload []byte) (code StatusCode, reason string) {
|
|
if len(payload) < 2 {
|
|
// We returning empty StatusCode here, preventing the situation
|
|
// when endpoint really sent code 1005 and we should return ProtocolError on that.
|
|
//
|
|
// In other words, we ignoring this rule [RFC6455:7.1.5]:
|
|
// If this Close control frame contains no status code, _The WebSocket
|
|
// Connection Close Code_ is considered to be 1005.
|
|
return code, reason
|
|
}
|
|
code = StatusCode(binary.BigEndian.Uint16(payload))
|
|
reason = string(payload[2:])
|
|
return code, reason
|
|
}
|
|
|
|
// ParseCloseFrameDataUnsafe is like ParseCloseFrameData except the thing
|
|
// that it does not copies payload bytes into reason, but prepares unsafe cast.
|
|
func ParseCloseFrameDataUnsafe(payload []byte) (code StatusCode, reason string) {
|
|
if len(payload) < 2 {
|
|
return code, reason
|
|
}
|
|
code = StatusCode(binary.BigEndian.Uint16(payload))
|
|
reason = btsToString(payload[2:])
|
|
return code, reason
|
|
}
|