go/neo/proto/msgpack: Fix decoding of IdTime

The data type of IdTime is 'Optional[float]' [1], [2]. Before this patch the
msgpack decoder could only decode 'IdTime' in case its data type was
'float'. Now it also supports the decoding of IdTime in case it is NIL.

[1] See here, the fifth argument is IdTime:

    https://lab.nexedi.com/nexedi/neoppod/-/blob/3ddb6663/neo/master/handlers/identification.py#L26-27

    This is found to be 'Optional[float]':

    https://lab.nexedi.com/nexedi/neoppod/-/blob/3ddb6663/neo/tests/protocol#L98

[2] This seems to be true for both, pre-msgpack and post-msgpack
    protocol, because in the pre-msgpack NEO/go there is already this
    note:

    https://lab.nexedi.com/kirr/neo/-/blob/1ad088c8/go/neo/proto/proto.go#L352-357

go/neo/proto/protogen.go

@@ -313,6 +313,7 @@ package proto
 
 import (
 	"encoding/binary"
+	"math"
 	"reflect"
 	"sort"
 
@@ -1137,7 +1138,7 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 	}
 
 	// mgetfloat emits mgetfloat<size>
-	mgetfloat := func(size int) {
+	mgetfloat := func(size int, optionalValue string) {
 		// delving into msgp - flush/prepare next site for overflow check
 		d.overflowCheck()
 		d.resetPos()
@@ -1146,7 +1147,15 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		d.emit("{")
 		d.emit("v, tail, err := msgp.ReadFloat%dBytes(data)", size)
 		d.emit("if err != nil {")
+		if optionalValue != "" {
+			d.emit("  tail, err = msgp.ReadNilBytes(data)")
+			d.emit("    if err != nil {")
 			d.emit("      return 0, mdecodeErr(%q, err)", d.pathName(assignto))
+			d.emit("  }")
+			d.emit("v = %v", optionalValue)
+		} else {
+			d.emit("  return 0, mdecodeErr(%q, err)", d.pathName(assignto))
+		}
 		d.emit("}")
 		d.emit("%s= %s", assignto, v)
 		d.emit("%v += uint64(len(data) - len(tail))", d.var_("nread"))
@@ -1154,6 +1163,14 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		d.emit("}")
 	}
 
+	// IdTime can be nil ('None' in py), in this case we use
+	// infinite -1, see
+	// https://lab.nexedi.com/kirr/neo/-/blob/1ad088c8/go/neo/proto/proto.go#L352-357
+	if typeName(userType) == "IdTime" {
+		mgetfloat(64, "math.Inf(-1)")
+		return
+	}
+
 	switch typ.Kind() {
 	case types.Bool:
 		d.emit("switch op := msgpack.Op(data[%v]); op {", d.n)
@@ -1175,7 +1192,7 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 	case types.Uint32:	mgetint("u", 32)
 	case types.Uint64:	mgetint("u", 64)
 
-	case types.Float64:	mgetfloat(64)
+	case types.Float64:	mgetfloat(64, "")
 	}
 }
 

go/neo/proto/zproto-marshal.go

@@ -6,6 +6,7 @@ package proto
 
 import (
 	"encoding/binary"
+	"math"
 	"reflect"
 	"sort"
 
@@ -426,9 +427,13 @@ func (p *RequestIdentification) neoMsgDecodeM(data []byte) (int, error) {
 	}
 	{
 		v, tail, err := msgp.ReadFloat64Bytes(data)
+		if err != nil {
+			tail, err = msgp.ReadNilBytes(data)
 			if err != nil {
 				return 0, mdecodeErr("RequestIdentification.IdTime", err)
 			}
+			v = math.Inf(-1)
+		}
 		p.IdTime = IdTime(v)
 		nread += uint64(len(data) - len(tail))
 		data = tail
@@ -1152,9 +1157,13 @@ func (p *NotifyNodeInformation) neoMsgDecodeM(data []byte) (int, error) {
 	}
 	{
 		v, tail, err := msgp.ReadFloat64Bytes(data)
+		if err != nil {
+			tail, err = msgp.ReadNilBytes(data)
 			if err != nil {
 				return 0, mdecodeErr("NotifyNodeInformation.IdTime", err)
 			}
+			v = math.Inf(-1)
+		}
 		p.IdTime = IdTime(v)
 		nread += uint64(len(data) - len(tail))
 		data = tail
@@ -1254,9 +1263,13 @@ func (p *NotifyNodeInformation) neoMsgDecodeM(data []byte) (int, error) {
 			data = data[3:]
 			{
 				v, tail, err := msgp.ReadFloat64Bytes(data)
+				if err != nil {
+					tail, err = msgp.ReadNilBytes(data)
 					if err != nil {
 						return 0, mdecodeErr("NotifyNodeInformation.IdTime", err)
 					}
+					v = math.Inf(-1)
+				}
 				(*a).IdTime = IdTime(v)
 				nread += uint64(len(data) - len(tail))
 				data = tail
@@ -6926,9 +6939,13 @@ func (p *AnswerNodeList) neoMsgDecodeM(data []byte) (int, error) {
 			data = data[3:]
 			{
 				v, tail, err := msgp.ReadFloat64Bytes(data)
+				if err != nil {
+					tail, err = msgp.ReadNilBytes(data)
 					if err != nil {
 						return 0, mdecodeErr("AnswerNodeList.IdTime", err)
 					}
+					v = math.Inf(-1)
+				}
 				(*a).IdTime = IdTime(v)
 				nread += uint64(len(data) - len(tail))
 				data = tail