global variable to control NaN allowed

op_msg.go

@@ -23,6 +23,9 @@ import (
 	"github.com/FerretDB/wire/wirebson"
 )
 
+// AllowNan false returns error when float64 nan is present in wire messages.
+var AllowNan = true
+
 // OpMsg is the main wire protocol message type.
 type OpMsg struct {
 	// The order of fields is weird to make the struct smaller due to alignment.
@@ -72,7 +75,7 @@ func (msg *OpMsg) SetSections(sections ...OpMsgSection) error {
 
 	msg.sections = sections
 
-	if debugbuild {
+	if debugbuild || !AllowNan {
 		if err := msg.check(); err != nil {
 			return lazyerrors.Error(err)
 		}
@@ -135,9 +138,18 @@ func (msg *OpMsg) msgbody() {}
 func (msg *OpMsg) check() error {
 	for _, s := range msg.sections {
 		for _, d := range s.documents {
-			if _, err := d.DecodeDeep(); err != nil {
+			doc, err := d.DecodeDeep()
+			if err != nil {
 				return lazyerrors.Error(err)
 			}
+
+			if AllowNan {
+				continue
+			}
+
+			if err = validateNan(doc); err != nil {
+				return err
+			}
 		}
 	}
 
@@ -241,7 +253,7 @@ func (msg *OpMsg) UnmarshalBinaryNocopy(b []byte) error {
 		return lazyerrors.Error(err)
 	}
 
-	if debugbuild {
+	if debugbuild || !AllowNan {
 		if err := msg.check(); err != nil {
 			return lazyerrors.Error(err)
 		}

validation.go

@@ -0,0 +1,47 @@
+// Copyright 2021 FerretDB Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package wire
+
+import (
+	"errors"
+	"github.com/FerretDB/wire/wirebson"
+	"math"
+)
+
+// validateNan returns error if float Nan was encountered.
+func validateNan(v any) error {
+	switch v := v.(type) {
+	case *wirebson.Document:
+		for _, f := range v.FieldNames() {
+			if err := validateNan(v.Get(f)); err != nil {
+				return err
+			}
+		}
+
+	case *wirebson.Array:
+		for i := range v.Len() {
+			if err := validateNan(v.Get(i)); err != nil {
+				return err
+			}
+		}
+
+	case float64:
+		if math.IsNaN(v) {
+			return errors.New("NaN is not supported")
+		}
+	}
+
+	return nil
+}