network-bridge script support for multiple external interfaces

diff -r 70aa62954e91 tools/examples/network-bridge
@@ -5,8 +5,8 @@
 # The script name to use is defined in /etc/xen/xend-config.sxp
 # in the network-script field.
 #
-# This script creates a bridge (default xen-br0), adds a device
-# (default eth0) to it, copies the IP addresses from the device
+# This script creates a bridge (default xen-br${virtnum}), adds a device
+# (default eth${virtnum}) to it, copies the IP addresses from the device
 # to the bridge and adjusts the routes accordingly.
 #
 # If all goes well, this should ensure that networking stays up.

@@ -20,8 +20,11 @@
 #
 # Vars:
 #
-# bridge     The bridge to use (default xen-br0).
-# netdev     The interface to add to the bridge (default eth0).
+# virtnum    Virtual device number to use (default 0). Numbers >=1
+#            require the netback driver to have nloopbacks set to a
+#            higher value than its default of 1.
+# bridge     The bridge to use (default xen-br${virtnum}).
+# netdev     The interface to add to the bridge (default eth${virtnum}).
 # antispoof  Whether to use iptables to prevent spoofing (default yes).
 #
 # start:

@@ -60,11 +63,12 @@
 # Pull variables in args in to environment.
 for arg ; do export "${arg}" ; done
 
-bridge=${bridge:-xen-br0}
-netdev=${netdev:-eth0}
+virtnum=${virtnum:-0}
+bridge=${bridge:-xen-br${virtnum}}
+netdev=${netdev:-eth${virtnum}}
 antispoof=${antispoof:-no}
 
-echo "*network $OP bridge=$bridge netdev=$netdev antispoof=$antispoof" >&2
+echo "*network $OP bridge=$bridge netdev=$netdev antispoof=$antispoof virtnum=$virtnum" >&2
 
 # Usage: transfer_addrs src dst
 # Copy all IP addresses (including aliases) from device $src to device $dst.

@@ -182,11 +186,11 @@
 
     create_bridge ${bridge}
 
-    if ifconfig 2>/dev/null | grep -q veth0 ; then
-        return
-    fi
-
-    if ifconfig veth0 2>/dev/null | grep -q veth0 ; then
+    if ifconfig 2>/dev/null | grep -q veth${virtnum} ; then
+        return
+    fi
+
+    if ifconfig veth${virtnum} 2>/dev/null | grep -q veth${virtnum} ; then
 	mac=`ifconfig ${netdev} | grep HWadd | sed -e 's/.*\(..:..:..:..:..:..\).*/\1/'`
 	if ! ifdown ${netdev} ; then
 		# if ifup didn't work, see if we have an ip= on cmd line

@@ -199,14 +203,14 @@
 		fi
 	fi
 	ip link set ${netdev} name p${netdev}
-	ip link set veth0 name ${netdev}
+	ip link set veth${virtnum} name ${netdev}
 	ifconfig p${netdev} 0.0.0.0 -arp down
 	ifconfig p${netdev} hw ether fe:ff:ff:ff:ff:ff
 	ifconfig ${netdev} hw ether ${mac}
-	add_to_bridge ${bridge} vif0.0
+	add_to_bridge ${bridge} vif0.${virtnum}
 	add_to_bridge ${bridge} p${netdev}
 	ip link set ${bridge} up
-	ip link set vif0.0 up
+	ip link set vif0.${virtnum} up
 	ip link set p${netdev} up
 	if ! ifup ${netdev} ; then
 		if [ ${kip} ] ; then

@@ -218,7 +222,7 @@
 		fi
         fi
     else
-	# old style without veth0
+	# old style without veth${virtnum}
 	transfer_addrs ${netdev} ${bridge}
         transfer_routes ${netdev} ${bridge}
     fi

@@ -233,10 +237,10 @@
         return
     fi
 
-    if ifconfig peth0 2>/dev/null | grep -q peth0 ; then
-
-        ifconfig vif0.0 down
-        mac=`ifconfig eth0 | grep HWadd | \
+    if ifconfig peth${virtnum} 2>/dev/null | grep -q peth${virtnum} ; then
+
+        ifconfig vif0.${virtnum} down
+        mac=`ifconfig eth${virtnum} | grep HWadd | \
             sed -e 's/.*\(..:..:..:..:..:..\).*/\1/'`
         ifconfig ${netdev} 0.0.0.0 down
         ifconfig ${netdev} hw ether fe:ff:ff:ff:ff:ff

@@ -245,11 +249,11 @@
         ifconfig p${netdev} hw ether ${mac} arp 
         brctl delif ${bridge} p${netdev}
 
-        ip link set eth0 name veth0
-        ip link set peth0 name eth0
+        ip link set eth${virtnum} name veth${virtnum}
+        ip link set peth${virtnum} name eth${virtnum}
         ifconfig ${bridge} down
         brctl delbr ${bridge}
-        ifup eth0
+        ifup eth${virtnum}
 
     else
         transfer_routes ${bridge} ${netdev}