selftests: net: use upstream mtools

Joachim kindly merged the IPv6 support in
https://github.com/troglobit/mtools/pull/2, so we can just use his
version now. A few more fixes subsequently came in for IPv6, so even
better.

Check that the deployed mtools version is 3.0 or above. Note that the
version check breaks compatibility with my fork where I didn't bump the
version, but I assume that won't be a problem.

Signed-off-by: Vladimir Oltean <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/forwarding/lib.sh

···
 	fi
 }
 
+# IPv6 support was added in v3.0
+check_mtools_version()
+{
+	local version="$(msend -v)"
+	local major
+
+	version=${version##msend version }
+	major=$(echo $version | cut -d. -f1)
+
+	if [ $major -lt 3 ]; then
+		echo "SKIP: expected mtools version 3.0, got $version"
+		exit $ksft_skip
+	fi
+}
+
 if [[ "$REQUIRE_JQ" = "yes" ]]; then
 	require_command jq
 fi
···
 	require_command $MZ
 fi
 if [[ "$REQUIRE_MTOOLS" = "yes" ]]; then
-	# https://github.com/vladimiroltean/mtools/
-	# patched for IPv6 support
+	# https://github.com/troglobit/mtools
 	require_command msend
 	require_command mreceive
+	check_mtools_version
 fi
 
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