expr: call expr->ops->snprintf only if defined

The notrack expression comes with no ->ops->snprintf, so skip this from
nftnl_expr_snprintf() if not set.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/expr.c b/src/expr.c
index 2779b3c42217dffeac8fab29c7095eeb11261a69..8d5c56206867652bdce0d15b53c51fdb48a5e593 100644 (file)
--- a/src/expr.c
+++ b/src/expr.c
@@ -281,6 +281,9 @@ int nftnl_expr_snprintf(char *buf, size_t size, const struct nftnl_expr *expr,
        int ret;
        unsigned int offset = 0, len = size;
 
+       if (!expr->ops->snprintf)
+               return 0;
+
        ret = expr->ops->snprintf(buf+offset, len, type, flags, expr);
        SNPRINTF_BUFFER_SIZE(ret, size, len, offset);