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package yamux
import (
"encoding/binary"
"fmt"
)
var (
// ErrInvalidVersion means we received a frame with an
// invalid version
ErrInvalidVersion = fmt.Errorf("invalid protocol version")
// ErrInvalidMsgType means we received a frame with an
// invalid message type
ErrInvalidMsgType = fmt.Errorf("invalid msg type")
// ErrSessionShutdown is used if there is a shutdown during
// an operation
ErrSessionShutdown = fmt.Errorf("session shutdown")
// ErrStreamsExhausted is returned if we have no more
// stream ids to issue
ErrStreamsExhausted = fmt.Errorf("streams exhausted")
// ErrDuplicateStream is used if a duplicate stream is
// opened inbound
ErrDuplicateStream = fmt.Errorf("duplicate stream initiated")
// ErrReceiveWindowExceeded indicates the window was exceeded
ErrRecvWindowExceeded = fmt.Errorf("recv window exceeded")
// ErrTimeout is used when we reach an IO deadline
ErrTimeout = fmt.Errorf("i/o deadline reached")
// ErrStreamClosed is returned when using a closed stream
ErrStreamClosed = fmt.Errorf("stream closed")
// ErrUnexpectedFlag is set when we get an unexpected flag
ErrUnexpectedFlag = fmt.Errorf("unexpected flag")
// ErrRemoteGoAway is used when we get a go away from the other side
ErrRemoteGoAway = fmt.Errorf("remote end is not accepting connections")
// ErrConnectionReset is sent if a stream is reset. This can happen
// if the backlog is exceeded, or if there was a remote GoAway.
ErrConnectionReset = fmt.Errorf("connection reset")
// ErrConnectionWriteTimeout indicates that we hit the "safety valve"
// timeout writing to the underlying stream connection.
ErrConnectionWriteTimeout = fmt.Errorf("connection write timeout")
// ErrKeepAliveTimeout is sent if a missed keepalive caused the stream close
ErrKeepAliveTimeout = fmt.Errorf("keepalive timeout")
)
const (
// protoVersion is the only version we support
protoVersion uint8 = 0
)
const (
// Data is used for data frames. They are followed
// by length bytes worth of payload.
typeData uint8 = iota
// WindowUpdate is used to change the window of
// a given stream. The length indicates the delta
// update to the window.
typeWindowUpdate
// Ping is sent as a keep-alive or to measure
// the RTT. The StreamID and Length value are echoed
// back in the response.
typePing
// GoAway is sent to terminate a session. The StreamID
// should be 0 and the length is an error code.
typeGoAway
)
const (
// SYN is sent to signal a new stream. May
// be sent with a data payload
flagSYN uint16 = 1 << iota
// ACK is sent to acknowledge a new stream. May
// be sent with a data payload
flagACK
// FIN is sent to half-close the given stream.
// May be sent with a data payload.
flagFIN
// RST is used to hard close a given stream.
flagRST
)
const (
// initialStreamWindow is the initial stream window size
initialStreamWindow uint32 = 256 * 1024
)
const (
// goAwayNormal is sent on a normal termination
goAwayNormal uint32 = iota
// goAwayProtoErr sent on a protocol error
goAwayProtoErr
// goAwayInternalErr sent on an internal error
goAwayInternalErr
)
const (
sizeOfVersion = 1
sizeOfType = 1
sizeOfFlags = 2
sizeOfStreamID = 4
sizeOfLength = 4
headerSize = sizeOfVersion + sizeOfType + sizeOfFlags +
sizeOfStreamID + sizeOfLength
)
type header []byte
func (h header) Version() uint8 {
return h[0]
}
func (h header) MsgType() uint8 {
return h[1]
}
func (h header) Flags() uint16 {
return binary.BigEndian.Uint16(h[2:4])
}
func (h header) StreamID() uint32 {
return binary.BigEndian.Uint32(h[4:8])
}
func (h header) Length() uint32 {
return binary.BigEndian.Uint32(h[8:12])
}
func (h header) String() string {
return fmt.Sprintf("Vsn:%d Type:%d Flags:%d StreamID:%d Length:%d",
h.Version(), h.MsgType(), h.Flags(), h.StreamID(), h.Length())
}
func (h header) encode(msgType uint8, flags uint16, streamID uint32, length uint32) {
h[0] = protoVersion
h[1] = msgType
binary.BigEndian.PutUint16(h[2:4], flags)
binary.BigEndian.PutUint32(h[4:8], streamID)
binary.BigEndian.PutUint32(h[8:12], length)
}
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