selftests: net: switch to socat in the GSO GRE test

Commit a985442fdecb ("selftests: net: properly support IPv6 in GSO GRE test")
is not compatible with:

  Ncat: Version 7.80 ( https://nmap.org/ncat )

(which is distributed with Fedora/Red Hat), tests fail with:

  nc: invalid option -- 'N'

Let's switch to socat which is far more dependable.

Fixes: 025efa0a82df ("selftests: add simple GSO GRE test")
Fixes: a985442fdecb ("selftests: net: properly support IPv6 in GSO GRE test")
Tested-by: Andrea Righi <andrea.righi@canonical.com>
Link: https://lore.kernel.org/r/20211111162929.530470-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/gre_gso.sh b/tools/testing/selftests/net/gre_gso.sh
index fdeb44d..3224651 100755 (executable)
--- a/tools/testing/selftests/net/gre_gso.sh
+++ b/tools/testing/selftests/net/gre_gso.sh
@@ -118,16 +118,18 @@ gre_gst_test_checks()
        local addr=$2
        local proto=$3
 
-       $NS_EXEC nc $proto -kl $port >/dev/null &
+       [ "$proto" == 6 ] && addr="[$addr]"
+
+       $NS_EXEC socat - tcp${proto}-listen:$port,reuseaddr,fork >/dev/null &
        PID=$!
        while ! $NS_EXEC ss -ltn | grep -q $port; do ((i++)); sleep 0.01; done
 
-       cat $TMPFILE | timeout 1 nc $proto -N $addr $port
+       cat $TMPFILE | timeout 1 socat -u STDIN TCP:$addr:$port
        log_test $? 0 "$name - copy file w/ TSO"
 
        ethtool -K veth0 tso off
 
-       cat $TMPFILE | timeout 1 nc $proto -N $addr $port
+       cat $TMPFILE | timeout 1 socat -u STDIN TCP:$addr:$port
        log_test $? 0 "$name - copy file w/ GSO"
 
        ethtool -K veth0 tso on
@@ -155,8 +157,8 @@ gre6_gso_test()
 
        sleep 2
 
-       gre_gst_test_checks GREv6/v4 172.16.2.2
-       gre_gst_test_checks GREv6/v6 2001:db8:1::2 -6
+       gre_gst_test_checks GREv6/v4 172.16.2.2 4
+       gre_gst_test_checks GREv6/v6 2001:db8:1::2 6
 
        cleanup
 }
@@ -212,8 +214,8 @@ if [ ! -x "$(command -v ip)" ]; then
        exit $ksft_skip
 fi
 
-if [ ! -x "$(command -v nc)" ]; then
-       echo "SKIP: Could not run test without nc tool"
+if [ ! -x "$(command -v socat)" ]; then
+       echo "SKIP: Could not run test without socat tool"
        exit $ksft_skip
 fi