Ensure backwards compatibility before modifying protocol
This change makes sure that things work smoothly when "we" are a newer version than our peer and have more fields in our messages than they do. Missing fields will be left at zero/nil. (The other side will ignore our extra fields, for the same effect.)
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parent
09b534b8a3
commit
a3ea9427d1
26
protocol.go
26
protocol.go
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@ -133,6 +133,10 @@ type encodable interface {
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AppendXDR([]byte) ([]byte, error)
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}
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type isEofer interface {
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IsEOF() bool
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}
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const (
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pingTimeout = 30 * time.Second
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pingIdleTime = 60 * time.Second
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@ -376,20 +380,36 @@ func (c *rawConnection) readMessage() (hdr header, msg encodable, err error) {
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}
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}
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// We check each returned error for the XDRError.IsEOF() method.
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// IsEOF()==true here means that the message contained fewer fields than
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// expected. It does not signify an EOF on the socket, because we've
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// successfully read a size value and that many bytes already. New fields
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// we expected but the other peer didn't send should be interpreted as
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// zero/nil, and if that's not valid we'll verify it somewhere else.
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switch hdr.msgType {
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case messageTypeIndex, messageTypeIndexUpdate:
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var idx IndexMessage
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err = idx.UnmarshalXDR(msgBuf)
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if xdrErr, ok := err.(isEofer); ok && xdrErr.IsEOF() {
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err = nil
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}
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msg = idx
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case messageTypeRequest:
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var req RequestMessage
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err = req.UnmarshalXDR(msgBuf)
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if xdrErr, ok := err.(isEofer); ok && xdrErr.IsEOF() {
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err = nil
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}
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msg = req
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case messageTypeResponse:
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var resp ResponseMessage
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err = resp.UnmarshalXDR(msgBuf)
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if xdrErr, ok := err.(isEofer); ok && xdrErr.IsEOF() {
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err = nil
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}
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msg = resp
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case messageTypePing, messageTypePong:
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@ -398,11 +418,17 @@ func (c *rawConnection) readMessage() (hdr header, msg encodable, err error) {
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case messageTypeClusterConfig:
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var cc ClusterConfigMessage
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err = cc.UnmarshalXDR(msgBuf)
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if xdrErr, ok := err.(isEofer); ok && xdrErr.IsEOF() {
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err = nil
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}
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msg = cc
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case messageTypeClose:
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var cm CloseMessage
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err = cm.UnmarshalXDR(msgBuf)
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if xdrErr, ok := err.(isEofer); ok && xdrErr.IsEOF() {
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err = nil
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}
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msg = cm
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default:
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