[Xen-changelog] Set hostname in DHCP config from the guest name, and if more than one interface

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User emellor@xxxxxxxxxxxxxxxxxxxxxx
# Node ID b20641d242723923de40030a63771770b04702d3
# Parent  5e617fd4850427ac4ac235969b36d78935103f19
Set hostname in DHCP config from the guest name, and if more than one interface
is specified, from guest-2, guest-3 etc.  Have the DHCP server send the
hostname to the guest.

Added a lock around DHCP config file frobbing, to avoid racing creation vs
deletion.

Signed-off-by: Ewan Mellor <ewan@xxxxxxxxxxxxx>

diff -r 5e617fd48504 -r b20641d24272 tools/examples/vif-nat
--- a/tools/examples/vif-nat    Sat Dec  3 00:51:36 2005
+++ b/tools/examples/vif-nat    Sat Dec  3 12:21:27 2005
@@ -42,14 +42,15 @@
 fi
 
 
+domid=$(echo "$XENBUS_PATH" | sed -n 's#.*/\([0-9]*\)/[0-9]*$#\1#p')
+vifid=$(echo "$XENBUS_PATH" | sed -n 's#.*/[0-9]*/\([0-9]*\)$#\1#p')
+vifid=$(( $vifid + 1 ))
+
+
 ip_from_dom()
 {
-  local domid=$(echo "$XENBUS_PATH" | sed -n 's#.*/\([0-9]*\)/[0-9]*$#\1#p')
-  local vifid=$(echo "$XENBUS_PATH" | sed -n 's#.*/[0-9]*/\([0-9]*\)$#\1#p')
-
   local domid1=$(( $domid / 256 ))
   local domid2=$(( $domid % 256 ))
-  vifid=$(( $vifid + 1 ))
 
   echo "10.$domid1.$domid2.$vifid/16"
 }
@@ -92,10 +93,17 @@
 network=$(dotted_quad $(( $vif_int & $intmask )) )
 
 
+hostname=$(xenstore_read "$XENBUS_PATH/domain" | tr -- '_.:/+' '-----')
+if [ "$vifid" != "1" ]
+then
+  hostname="$hostname-$vifid"
+fi
+
+
 dhcp_remove_entry()
 {
   local tmpfile=$(mktemp)
-  grep -v "host Xen-${vif/./-}" "$dhcpd_conf_file" >"$tmpfile"
+  grep -v "host $hostname" "$dhcpd_conf_file" >"$tmpfile"
   if diff "$tmpfile" "$dhcpd_conf_file" >/dev/null
   then
     rm "$tmpfile"
@@ -107,18 +115,21 @@
 
 dhcp_up()
 {
+  claim_lock "vif-nat-dhcp"
   dhcp_remove_entry
   mac=$(xenstore_read "$XENBUS_PATH/mac")
   echo >>"$dhcpd_conf_file" \
-"host Xen-${vif/./-} { hardware ethernet $mac; fixed-address $vif_ip; option 
routers $router_ip; }"
-
-  "$dhcpd_init_file" restart
+"host $hostname { hardware ethernet $mac; fixed-address $vif_ip; option 
routers $router_ip; option host-name \"$hostname\"; }"
+  release_lock "vif-nat-dhcp"
+  "$dhcpd_init_file" restart || true
 }
 
 
 dhcp_down()
 {
+  claim_lock "vif-nat-dhcp"
   dhcp_remove_entry
+  release_lock "vif-nat-dhcp"
   "$dhcpd_init_file" restart || true # We need to ignore failure because
                                      # ISC dhcpd 3 borks if there is nothing
                                      # for it to do, which is the case if

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