xtables-translate: fix multiple spaces issue

This patch fixes a multiple spaces issue. The problem arises when a rule
set loaded through iptables-compat-restore is listed in nft.

Before this commit, two spaces were printed after every match
translation:

$ sudo iptables-save
*filter
:INPUT ACCEPT [0:0]
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m multiport --dports 80:85 -m ttl --ttl-gt 5 -j ACCEPT
COMMIT

$ sudo iptables-compat-restore iptables-save

$ sudo nft list ruleset
table ip filter {
    chain INPUT {
        type filter hook input priority 0; policy accept;
        ct state related,established  counter packets 0 bytes 0 accept
                                    ^^
        ip protocol tcp tcp dport 80-85  ip ttl gt 5  counter packets 0 bytes 0 accept
                                       ^^           ^^
    }
}

Signed-off-by: Pablo M. Bermudo Garay <pablombg@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/extensions/libxt_udp.c b/extensions/libxt_udp.c
index 9af782e4..d8e286ac 100644
--- a/extensions/libxt_udp.c
+++ b/extensions/libxt_udp.c
@@ -156,29 +156,31 @@ static int udp_xlate(const void *ip, const struct xt_entry_match *match,
 		     struct xt_xlate *xl, int numeric)
 {
 	const struct xt_udp *udpinfo = (struct xt_udp *)match->data;
+	char *space= "";
 
 	if (udpinfo->spts[0] != 0 || udpinfo->spts[1] != 0xFFFF) {
 		if (udpinfo->spts[0] != udpinfo->spts[1]) {
-			xt_xlate_add(xl,"udp sport %s%u-%u ",
+			xt_xlate_add(xl,"udp sport %s%u-%u",
 				   udpinfo->invflags & XT_UDP_INV_SRCPT ?
 					 "!= ": "",
 				   udpinfo->spts[0], udpinfo->spts[1]);
 		} else {
-			xt_xlate_add(xl, "udp sport %s%u ",
+			xt_xlate_add(xl, "udp sport %s%u",
 				   udpinfo->invflags & XT_UDP_INV_SRCPT ?
 					 "!= ": "",
 				   udpinfo->spts[0]);
 		}
+		space = " ";
 	}
 
 	if (udpinfo->dpts[0] != 0 || udpinfo->dpts[1] != 0xFFFF) {
 		if (udpinfo->dpts[0]  != udpinfo->dpts[1]) {
-			xt_xlate_add(xl,"udp dport %s%u-%u ",
+			xt_xlate_add(xl,"%sudp dport %s%u-%u", space,
 				   udpinfo->invflags & XT_UDP_INV_SRCPT ?
 					 "!= ": "",
 				   udpinfo->dpts[0], udpinfo->dpts[1]);
 		} else {
-			xt_xlate_add(xl,"udp dport %s%u ",
+			xt_xlate_add(xl,"%sudp dport %s%u", space,
 				   udpinfo->invflags & XT_UDP_INV_SRCPT ?
 					 "!= ": "",
 				   udpinfo->dpts[0]);