improve netdev, and add possibility to put no netdev

vm-start.sh

@@ -37,9 +37,9 @@ OPTION available
     options=<option>        additinal options to give to qemu. By default is
                             -display gtk -vga qxl
     create_disk=<loc_disk>  Def a create disk to boot on. Is necessary for using create, or need the variable INSTALLATION_DISK_LOCATION to be set.
-    net=nat                 Add a nat connection to the vm. By default there is already one #TODO
-    net=tap<tapInterface>   Connect the vm to the tap interface <tapInterface>. Please use the script set-tap.sh as root to create the tap interface. #TODO
-    net=none                The vm will have no network interface #TODO
+    net=nat:id                 Add a nat connection to the vm. By default there is already one.
+    net=tap:<tapInterface>   Connect the vm to the tap interface <tapInterface>. Please use the script set-tap.sh as root to create the tap interface. #TODO
+    net=none                The vm will have no network interface
 "
 
 MAIN_LOCATION="$HOME/virtual_machine"
@@ -100,14 +100,18 @@ EOF
 }
 
 start_the_vm() {
+
+    if [ "${network}" == "" ]
+    then
+        network="-net nic \
+            -net user${FORWARD},hostname=${VMHOSTNAME}"
+    fi
+
     qemu-system-x86_64 \
         -enable-kvm \
         -cpu host \
         -smp "$NPROC" \
-        -net nic \
-        -net user"$FORWARD",hostname="$VMHOSTNAME" \
-        -netdev user,id=id01,net=192.168.76.0/24,dhcpstart=192.168.76.9 \
-        -device virtio-net,netdev=id01 \
+        $network \
         -m "$MEMORY" \
         -drive file="${MAIN_LOCATION}/${LOCATION}/${VMDRIVE}",index=2,id=maindrive,media=disk \
         $OPTION
@@ -195,6 +199,28 @@ set_uefi() {
 
 }
 
+set_net() {
+    case "${1%:*}" in
+        "nat")
+            echo "ajout de l'interface ${1#*:}"
+            network="${network} \
+                -netdev user,id=${1#*:} \
+                -device virtio-net,netdev=${1#*:}"
+            ;;
+        "tap")
+            echo "tap"
+            ;;
+        "none")
+            echo "no interface will be connected."
+            network="-nic none"
+            ;;
+        *)
+            echo "type ${1%:*} not known, it should be either nat, tap or none" >&2
+            exit 1
+            ;;
+    esac
+}
+
 
 
 # change active directory to became the one is stored vm-start. In case it is impossible, quit.
@@ -262,6 +288,10 @@ for (( i=3; i<=$#; i++)); do
         "create_disk")
             INSTALLATION_DISK_LOCATION="${!i#*=}"
             ;;
+        "net")
+            param="${!i#*=}"
+            set_net "${param}"
+            ;;
     esac
 done