feat(expressions): add contentLength to bot expressions (#1120)

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/policy/celchecker.go

@@ -61,6 +61,8 @@ func (cr *CELRequest) ResolveName(name string) (any, bool) {
 	switch name {
 	case "remoteAddress":
 		return cr.Header.Get("X-Real-Ip"), true
+	case "contentLength":
+		return cr.ContentLength, true
 	case "host":
 		return cr.Host, true
 	case "method":

lib/policy/expressions/environment.go

@@ -19,6 +19,7 @@ func BotEnvironment() (*cel.Env, error) {
 	return New(
 		// Variables exposed to CEL programs:
 		cel.Variable("remoteAddress", cel.StringType),
+		cel.Variable("contentLength", cel.IntType),
 		cel.Variable("host", cel.StringType),
 		cel.Variable("method", cel.StringType),
 		cel.Variable("userAgent", cel.StringType),