package internet import "context" type systemDialer int const systemDialerKey systemDialer = 0 func ContextWithLookupDomain(ctx context.Context, domain string) context.Context { return context.WithValue(ctx, systemDialerKey, domain) } func LookupDomainFromContext(ctx context.Context) string { if domain, ok := ctx.Value(systemDialerKey).(string); ok { return domain } return "" }