casts.go: Checking for different variants of Inf , Infinity and NaN(e…

…liminating signs and checking for all possible cases)

Signed-off-by: sikehish <[email protected]>

topdown/casts.go

@@ -6,6 +6,7 @@ package topdown
 
 import (
 	"strconv"
+	"strings"
 
 	"github.com/open-policy-agent/opa/ast"
 	"github.com/open-policy-agent/opa/topdown/builtins"
@@ -25,7 +26,10 @@ func builtinToNumber(_ BuiltinContext, operands []*ast.Term, iter func(*ast.Term
 	case ast.String:
 		strValue := string(a)
 
-		if strValue == "Inf" || strValue == "Infinity" || strValue == "NaN" {
+		trimmedVal := strings.TrimLeft(strValue, "+-")
+		lowerCaseVal := strings.ToLower(trimmedVal)
+
+		if lowerCaseVal == "inf" || lowerCaseVal == "infinity" || lowerCaseVal == "nan" {
 			return builtins.NewOperandTypeErr(1, operands[0].Value, "valid number string")
 		}