selftests: nft_nat: switch port shadow test cases to socat

There are now at least three distinct flavours of netcat/nc tool:
'original' version, one version ported from openbsd and nmap-ncat.

The script only works with original because it sets SOREUSEPORT option.

Other nc versions return 'port already in use' error and port shadow test fails:

PASS: inet IPv6 redirection for ns2-hMHcaRvx
nc: bind failed: Address already in use
ERROR: portshadow test default: got reply from "ROUTER", not CLIENT as intended

Switch to socat instead.

Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/tools/testing/selftests/netfilter/nft_nat.sh b/tools/testing/selftests/netfilter/nft_nat.sh
index c62e4e2..d88867d 100755 (executable)
--- a/tools/testing/selftests/netfilter/nft_nat.sh
+++ b/tools/testing/selftests/netfilter/nft_nat.sh
@@ -760,20 +760,20 @@ test_port_shadow()
        local logmsg=""
 
        # make shadow entry, from client (ns2), going to (ns1), port 41404, sport 1405.
-       echo "fake-entry" | ip netns exec "$ns2" nc -w 1 -p 1405 -u "$daddrc" 41404 > /dev/null
+       echo "fake-entry" | ip netns exec "$ns2" timeout 1 socat -u STDIN UDP:"$daddrc":41404,sourceport=1405
 
-       echo ROUTER | ip netns exec "$ns0" nc -w 5 -u -l -p 1405 >/dev/null 2>&1 &
-       nc_r=$!
+       echo ROUTER | ip netns exec "$ns0" timeout 5 socat -u STDIN UDP4-LISTEN:1405 &
+       sc_r=$!
 
-       echo CLIENT | ip netns exec "$ns2" nc -w 5 -u -l -p 1405 >/dev/null 2>&1 &
-       nc_c=$!
+       echo CLIENT | ip netns exec "$ns2" timeout 5 socat -u STDIN UDP4-LISTEN:1405,reuseport &
+       sc_c=$!
 
        sleep 0.3
 
        # ns1 tries to connect to ns0:1405.  With default settings this should connect
        # to client, it matches the conntrack entry created above.
 
-       result=$(echo "" | ip netns exec "$ns1" nc -w 1 -p 41404 -u "$daddrs" 1405)
+       result=$(echo "data" | ip netns exec "$ns1" timeout 1 socat - UDP:"$daddrs":1405,sourceport=41404)
 
        if [ "$result" = "$expect" ] ;then
                echo "PASS: portshadow test $test: got reply from ${expect}${logmsg}"
@@ -782,7 +782,7 @@ test_port_shadow()
                ret=1
        fi
 
-       kill $nc_r $nc_c 2>/dev/null
+       kill $sc_r $sc_c 2>/dev/null
 
        # flush udp entries for next test round, if any
        ip netns exec "$ns0" conntrack -F >/dev/null 2>&1
@@ -852,6 +852,18 @@ test_port_shadowing()
 {
        local family="ip"
 
+       conntrack -h >/dev/null 2>&1
+       if [ $? -ne 0 ];then
+               echo "SKIP: Could not run nat port shadowing test without conntrack tool"
+               return
+       fi
+
+       socat -h > /dev/null 2>&1
+       if [ $? -ne 0 ];then
+               echo "SKIP: Could not run nat port shadowing test without socat tool"
+               return
+       fi
+
        ip netns exec "$ns0" sysctl net.ipv4.conf.veth0.forwarding=1 > /dev/null
        ip netns exec "$ns0" sysctl net.ipv4.conf.veth1.forwarding=1 > /dev/null