Fix processing of CIDRs with mask 0

diff --git a/iptables.c b/iptables.c
index df0d704..7d91452 100644 (file)
--- a/iptables.c
+++ b/iptables.c
@@ -609,7 +609,10 @@ fw3_ipt_rule_in_out(struct fw3_ipt_rule *r,
 static void
 ip4prefix2mask(int prefix, struct in_addr *mask)
 {
-       mask->s_addr = htonl(~((1 << (32 - prefix)) - 1));
+       if (prefix > 0)
+               mask->s_addr = htonl(~((1 << (32 - prefix)) - 1));
+       else
+               mask->s_addr = 0;
 }
 
 #ifndef DISABLE_IPV6