network: change vif-route-qubes-nat parameters

Keep "main" IP (the one in xenstore) as the one seen by the netvm, and
pass the "fake" one (the one seen by the VM) as script parameter.

Fixes QubesOS/qubes-issues#1143

network/vif-qubes-nat.sh

@@ -9,6 +9,24 @@ netvm_if="${vif}"
 netns_netvm_if="${vif}-p"
 netns_appvm_if="${vif}"
 
+#
+#               .----------------------------------.
+#               |          NetVM/ProxyVM           |
+# .------------.|.------------------.              |
+# |   AppVM    ||| $netns namespace |              |
+# |            |||                  |              |
+# |  eth0<--------->$netns_appvm_if |              |
+# |$appvm_ip   |||   $appvm_gw_ip   |              |
+# |$appvm_gw_ip|||         ^        |              |
+# '------------'||         |NAT     |              |
+#               ||         v        |              |
+#               ||  $netns_netvm_if<--->$netvm_if  |
+#               ||     $netvm_ip    |  $netvm_gw_ip|
+#               |'------------------'              |
+#               '----------------------------------'
+#
+
+
 function run
 {
     #echo "$@" >> /var/log/qubes-nat.log
@@ -20,8 +38,6 @@ function netns
     run ip netns exec "$netns" "$@"
 }
 
-
-
 run ip addr flush dev "$netns_appvm_if"
 run ip netns delete "$netns" || :
 
@@ -32,7 +48,6 @@ if test "$command" == online; then
     run ip link add "$netns_netvm_if" type veth peer name "$netvm_if"
     run ip link set "$netns_netvm_if" netns "$netns"
 
-
     netns ip6tables -t raw -I PREROUTING -j DROP
     netns ip6tables -P INPUT DROP
     netns ip6tables -P FORWARD DROP

network/vif-route-qubes-nat

@@ -20,15 +20,17 @@
 #         this script).
 #============================================================================
 
+# IPs as seen by the VM
 appvm_gw_ip="$1"
-netvm_ip="$2"
+appvm_ip="$2"
 shift 2
 
 dir=$(dirname "$0")
 . "$dir/vif-common.sh"
 
 if [ "${ip}" ]; then
-    appvm_ip="$ip"
+    # IPs as seen by this VM
+    netvm_ip="$ip"
     netvm_gw_ip=`qubesdb-read /qubes-netvm-gateway`
     netvm_dns2_ip=`qubesdb-read /qubes-netvm-secondary-dns`