selftests: nft_concat_range: add socat support

There are different flavors of 'nc' around, this script fails on
my test vm because 'nc' is 'nmap-ncat' which isn't 100% compatible.

Add socat support and use it if available.
Signed-off-by: Florian Westphal <fw@strlen.de>

tools/testing/selftests/netfilter/nft_concat_range.sh

@@ -91,7 +91,7 @@ src
 start		1
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	3
@@ -116,7 +116,7 @@ src
 start		10
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp6
 
 race_repeat	3
@@ -141,7 +141,7 @@ src
 start		1
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	0
@@ -163,7 +163,7 @@ src		mac
 start		10
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp6
 
 race_repeat	0
@@ -185,7 +185,7 @@ src		mac proto
 start		10
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp6
 
 race_repeat	0
@@ -207,7 +207,7 @@ src		addr4
 start		1
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	3
@@ -227,7 +227,7 @@ src		addr6 port
 start		10
 count		5
 src_delta	2000
-tools		sendip nc
+tools		sendip socat nc
 proto		udp6
 
 race_repeat	3
@@ -247,7 +247,7 @@ src		mac proto addr4
 start		1
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	0
@@ -264,7 +264,7 @@ src		mac
 start		1
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	0
@@ -286,7 +286,7 @@ src		mac addr4
 start		1
 count		5
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	0
@@ -337,7 +337,7 @@ src		addr4
 start		1
 count		5
 src_delta	2000
-tools		sendip nc
+tools		sendip socat nc
 proto		udp
 
 race_repeat	3
@@ -363,7 +363,7 @@ src		mac
 start		1
 count		1
 src_delta	2000
-tools		sendip nc bash
+tools		sendip socat nc bash
 proto		udp
 
 race_repeat	0
@@ -541,6 +541,24 @@ setup_send_udp() {
 			dst_port=
 			src_addr4=
 		}
+	elif command -v socat -v >/dev/null; then
+		send_udp() {
+			if [ -n "${src_addr4}" ]; then
+				B ip addr add "${src_addr4}" dev veth_b
+				__socatbind=",bind=${src_addr4}"
+				if [ -n "${src_port}" ];then
+					__socatbind="${__socatbind}:${src_port}"
+				fi
+			fi
+
+			ip addr add "${dst_addr4}" dev veth_a 2>/dev/null
+			[ -z "${dst_port}" ] && dst_port=12345
+
+			echo "test4" | B socat -t 0.01 STDIN UDP4-DATAGRAM:${dst_addr4}:${dst_port}"${__socatbind}"
+
+			src_addr4=
+			src_port=
+		}
 	elif command -v nc >/dev/null; then
 		if nc -u -w0 1.1.1.1 1 2>/dev/null; then
 			# OpenBSD netcat
@@ -606,6 +624,29 @@ setup_send_udp6() {
 			dst_port=
 			src_addr6=
 		}
+	elif command -v socat -v >/dev/null; then
+		send_udp6() {
+			ip -6 addr add "${dst_addr6}" dev veth_a nodad \
+				2>/dev/null
+
+			__socatbind6=
+
+			if [ -n "${src_addr6}" ]; then
+				if [ -n "${src_addr6} != "${src_addr6_added} ]; then
+					B ip addr add "${src_addr6}" dev veth_b nodad
+
+					src_addr6_added=${src_addr6}
+				fi
+
+				__socatbind6=",bind=[${src_addr6}]"
+
+				if [ -n "${src_port}" ] ;then
+					__socatbind6="${__socatbind6}:${src_port}"
+				fi
+			fi
+
+			echo "test6" | B socat -t 0.01 STDIN UDP6-DATAGRAM:[${dst_addr6}]:${dst_port}"${__socatbind6}"
+		}
 	elif command -v nc >/dev/null && nc -u -w0 1.1.1.1 1 2>/dev/null; then
 		# GNU netcat might not work with IPv6, try next tool
 		send_udp6() {