Use hosts public ip address in rootless containers

Add first non localhost ipv4 of all host interfaces as destination
for host.contaners.internal for rootless containers.

Fixes: containers#12000

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

libpod/container_internal_linux.go

@@ -2159,11 +2159,15 @@ func (c *Container) getHosts() string {
 				}
 			}
 		} else if c.config.NetMode.IsSlirp4netns() {
-			gatewayIP, err := GetSlirp4netnsGateway(c.slirp4netnsSubnet)
-			if err != nil {
-				logrus.Warn("Failed to determine gatewayIP: ", err.Error())
+			if ip := butil.LocalIP(); ip != "" {
+				hosts += fmt.Sprintf("%s\t%s\n", ip, "host.containers.internal")
 			} else {
-				hosts += fmt.Sprintf("%s host.containers.internal\n", gatewayIP.String())
+				gatewayIP, err := GetSlirp4netnsGateway(c.slirp4netnsSubnet)
+				if err != nil {
+					logrus.Warn("Failed to determine gatewayIP: ", err.Error())
+				} else {
+					hosts += fmt.Sprintf("%s host.containers.internal\n", gatewayIP.String())
+				}
 			}
 		} else {
 			logrus.Debug("Network configuration does not support host.containers.internal address")

test/system/500-networking.bats

@@ -124,10 +124,11 @@ load helpers
 
 @test "podman run with slirp4ns assigns correct addresses to /etc/hosts" {
     CIDR="$(random_rfc1918_subnet)"
+    IP=$(hostname -I | cut -f 1 -d " ")
     local conname=con-$(random_string 10)
     run_podman run --rm --network slirp4netns:cidr="${CIDR}.0/24" \
                 --name $conname --hostname $conname $IMAGE cat /etc/hosts
-    is "$output"   ".*${CIDR}.2 host.containers.internal"   "host.containers.internal should be the cidr+2 address"
+    is "$output"   ".*${IP}	host.containers.internal"   "host.containers.internal should be the first host ipv4 address"
     is "$output"   ".*${CIDR}.100	$conname $conname"   "$conname should be the cidr+100 address"
 }