network: use arping2, if available

fixes https://github.com/dracutdevs/dracut/issues/135

modules.d/40network/dhclient-script.sh

@@ -159,11 +159,18 @@ case $reason in
             read layer2 < /sys/class/net/$netif/device/layer2
         fi
         if [ "$layer2" != "0" ]; then
+            if command -v arping2 >/dev/null; then
+                if arping2 -q -C 1 -c 2 -I $netif $new_ip_address ; then
+                    warn "Duplicate address detected for $new_ip_address while doing dhcp. retrying"
+                    exit 1
+                fi
+            else
                 if ! arping -f -q -D -c 2 -I $netif $new_ip_address ; then
                     warn "Duplicate address detected for $new_ip_address while doing dhcp. retrying"
                     exit 1
                 fi
             fi
+        fi
         unset layer2
         setup_interface
         set | while read line || [ -n "$line" ]; do

modules.d/40network/ifup.sh

@@ -110,10 +110,17 @@ do_static() {
         ip addr add $ip/$mask ${srv:+peer $srv} dev $netif
         wait_for_ipv6_dad $netif
     else
-        if ! arping -f -q -D -c 2 -I $netif $ip; then
+        if command -v arping2 >/dev/null; then
+            if arping2 -q -C 1 -c 2 -I $netif $ip ; then
                 warn "Duplicate address detected for $ip for interface $netif."
                 return 1
             fi
+        else
+            if ! arping -f -q -D -c 2 -I $netif $ip ; then
+                warn "Duplicate address detected for $ip for interface $netif."
+                return 1
+            fi
+        fi
         ip addr flush dev $netif
         ip addr add $ip/$mask ${srv:+peer $srv} brd + dev $netif
     fi

modules.d/40network/module-setup.sh

@@ -4,7 +4,8 @@
 check() {
     local _program
 
-    require_binaries ip arping dhclient || return 1
+    require_binaries ip dhclient || return 1
+    require_any_binaries arping arping2 || return 1
 
     return 255
 }
@@ -23,7 +24,7 @@ installkernel() {
 # called by dracut
 install() {
     local _arch _i _dir
-    inst_multiple ip arping dhclient sed awk
+    inst_multiple ip arping arping2 dhclient sed awk
     inst_multiple -o ping ping6
     inst_multiple -o brctl
     inst_multiple -o teamd teamdctl teamnl

modules.d/40network/net-lib.sh

@@ -169,8 +169,12 @@ setup_net() {
     fi
 
     if [ "$layer2" != "0" ] && [ -n "$dest" ] && ! strstr "$dest" ":"; then
+        if command -v arping2 >/dev/null; then
+            arping2 -q -C 1 -c 60 -I $netif $dest || info "Resolving $dest via ARP on $netif failed"
+        else
             arping -q -f -w 60 -I $netif $dest || info "Resolving $dest via ARP on $netif failed"
         fi
+    fi
     unset layer2
 
     > /tmp/net.$netif.did-setup