vendor/github.com/hashicorp/yamux/const.go

   1 package yamux
   2
   3 import (
   4         "encoding/binary"
   5         "fmt"
   6 )
   7
   8 var (
   9         // ErrInvalidVersion means we received a frame with an
  10         // invalid version
  11         ErrInvalidVersion = fmt.Errorf("invalid protocol version")
  12
  13         // ErrInvalidMsgType means we received a frame with an
  14         // invalid message type
  15         ErrInvalidMsgType = fmt.Errorf("invalid msg type")
  16
  17         // ErrSessionShutdown is used if there is a shutdown during
  18         // an operation
  19         ErrSessionShutdown = fmt.Errorf("session shutdown")
  20
  21         // ErrStreamsExhausted is returned if we have no more
  22         // stream ids to issue
  23         ErrStreamsExhausted = fmt.Errorf("streams exhausted")
  24
  25         // ErrDuplicateStream is used if a duplicate stream is
  26         // opened inbound
  27         ErrDuplicateStream = fmt.Errorf("duplicate stream initiated")
  28
  29         // ErrReceiveWindowExceeded indicates the window was exceeded
  30         ErrRecvWindowExceeded = fmt.Errorf("recv window exceeded")
  31
  32         // ErrTimeout is used when we reach an IO deadline
  33         ErrTimeout = fmt.Errorf("i/o deadline reached")
  34
  35         // ErrStreamClosed is returned when using a closed stream
  36         ErrStreamClosed = fmt.Errorf("stream closed")
  37
  38         // ErrUnexpectedFlag is set when we get an unexpected flag
  39         ErrUnexpectedFlag = fmt.Errorf("unexpected flag")
  40
  41         // ErrRemoteGoAway is used when we get a go away from the other side
  42         ErrRemoteGoAway = fmt.Errorf("remote end is not accepting connections")
  43
  44         // ErrConnectionReset is sent if a stream is reset. This can happen
  45         // if the backlog is exceeded, or if there was a remote GoAway.
  46         ErrConnectionReset = fmt.Errorf("connection reset")
  47
  48         // ErrConnectionWriteTimeout indicates that we hit the "safety valve"
  49         // timeout writing to the underlying stream connection.
  50         ErrConnectionWriteTimeout = fmt.Errorf("connection write timeout")
  51
  52         // ErrKeepAliveTimeout is sent if a missed keepalive caused the stream close
  53         ErrKeepAliveTimeout = fmt.Errorf("keepalive timeout")
  54 )
  55
  56 const (
  57         // protoVersion is the only version we support
  58         protoVersion uint8 = 0
  59 )
  60
  61 const (
  62         // Data is used for data frames. They are followed
  63         // by length bytes worth of payload.
  64         typeData uint8 = iota
  65
  66         // WindowUpdate is used to change the window of
  67         // a given stream. The length indicates the delta
  68         // update to the window.
  69         typeWindowUpdate
  70
  71         // Ping is sent as a keep-alive or to measure
  72         // the RTT. The StreamID and Length value are echoed
  73         // back in the response.
  74         typePing
  75
  76         // GoAway is sent to terminate a session. The StreamID
  77         // should be 0 and the length is an error code.
  78         typeGoAway
  79 )
  80
  81 const (
  82         // SYN is sent to signal a new stream. May
  83         // be sent with a data payload
  84         flagSYN uint16 = 1 << iota
  85
  86         // ACK is sent to acknowledge a new stream. May
  87         // be sent with a data payload
  88         flagACK
  89
  90         // FIN is sent to half-close the given stream.
  91         // May be sent with a data payload.
  92         flagFIN
  93
  94         // RST is used to hard close a given stream.
  95         flagRST
  96 )
  97
  98 const (
  99         // initialStreamWindow is the initial stream window size
 100         initialStreamWindow uint32 = 256 * 1024
 101 )
 102
 103 const (
 104         // goAwayNormal is sent on a normal termination
 105         goAwayNormal uint32 = iota
 106
 107         // goAwayProtoErr sent on a protocol error
 108         goAwayProtoErr
 109
 110         // goAwayInternalErr sent on an internal error
 111         goAwayInternalErr
 112 )
 113
 114 const (
 115         sizeOfVersion  = 1
 116         sizeOfType     = 1
 117         sizeOfFlags    = 2
 118         sizeOfStreamID = 4
 119         sizeOfLength   = 4
 120         headerSize     = sizeOfVersion + sizeOfType + sizeOfFlags +
 121                 sizeOfStreamID + sizeOfLength
 122 )
 123
 124 type header []byte
 125
 126 func (h header) Version() uint8 {
 127         return h[0]
 128 }
 129
 130 func (h header) MsgType() uint8 {
 131         return h[1]
 132 }
 133
 134 func (h header) Flags() uint16 {
 135         return binary.BigEndian.Uint16(h[2:4])
 136 }
 137
 138 func (h header) StreamID() uint32 {
 139         return binary.BigEndian.Uint32(h[4:8])
 140 }
 141
 142 func (h header) Length() uint32 {
 143         return binary.BigEndian.Uint32(h[8:12])
 144 }
 145
 146 func (h header) String() string {
 147         return fmt.Sprintf("Vsn:%d Type:%d Flags:%d StreamID:%d Length:%d",
 148                 h.Version(), h.MsgType(), h.Flags(), h.StreamID(), h.Length())
 149 }
 150
 151 func (h header) encode(msgType uint8, flags uint16, streamID uint32, length uint32) {
 152         h[0] = protoVersion
 153         h[1] = msgType
 154         binary.BigEndian.PutUint16(h[2:4], flags)
 155         binary.BigEndian.PutUint32(h[4:8], streamID)
 156         binary.BigEndian.PutUint32(h[8:12], length)
 157 }