network: add dnsmasq option 'dhcp-authoritative'

The dnsmasq man page recommends that dhcp-authoritative "should be
set when dnsmasq is definitely the only DHCP server on a network".
This is the case for libvirt-managed virtual networks.

The effect of this is that VMs that fail to renew their DHCP lease
in time (e.g. if the VM or host is suspended) will be able to
re-acquire the lease even if it's expired, unless the IP address has
been taken by some other host. This avoids various annoyances caused
by changing VM IP addresses.

src/network/bridge_driver.c

@@ -1258,8 +1258,10 @@ networkDnsmasqConfContents(virNetworkObjPtr network,
 
         /* Note: the following is IPv4 only */
         if (VIR_SOCKET_ADDR_IS_FAMILY(&ipdef->address, AF_INET)) {
-            if (ipdef->nranges || ipdef->nhosts)
+            if (ipdef->nranges || ipdef->nhosts) {
                 virBufferAddLit(&configbuf, "dhcp-no-override\n");
+                virBufferAddLit(&configbuf, "dhcp-authoritative\n");
+            }
 
             if (ipdef->tftproot) {
                 virBufferAddLit(&configbuf, "enable-tftp\n");

tests/networkxml2confdata/dhcp6-nat-network.conf

@@ -10,6 +10,7 @@ bind-dynamic
 interface=virbr0
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-range=2001:db8:ac10:fd01::1:10,2001:db8:ac10:fd01::1:ff,64
 dhcp-lease-max=493
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile

tests/networkxml2confdata/dhcp6host-routed-network.conf

@@ -10,6 +10,7 @@ bind-dynamic
 interface=virbr1
 dhcp-range=192.168.122.1,static
 dhcp-no-override
+dhcp-authoritative
 dhcp-range=2001:db8:ac10:fd01::1,static,64
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/local.hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/local.addnhosts

tests/networkxml2confdata/isolated-network.conf

@@ -12,6 +12,7 @@ dhcp-option=3
 no-resolv
 dhcp-range=192.168.152.2,192.168.152.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/private.hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/private.addnhosts

tests/networkxml2confdata/nat-network-dns-srv-record-minimal.conf

@@ -15,6 +15,7 @@ listen-address=10.24.10.1
 srv-host=_name._tcp
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts

tests/networkxml2confdata/nat-network-dns-srv-record.conf

@@ -17,6 +17,7 @@ srv-host=_name6._tcp.test6.com,test6.example.com,6666,0,666
 srv-host=_name7._tcp.test7.com,test7.example.com,1,0,777
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts

tests/networkxml2confdata/nat-network-dns-txt-record.conf

@@ -11,6 +11,7 @@ interface=virbr0
 txt-record=example,example value
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts

tests/networkxml2confdata/nat-network-name-with-quotes.conf

@@ -15,6 +15,7 @@ listen-address=10.24.10.1
 srv-host=_name._tcp
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default"with"quotes".hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/default"with"quotes".addnhosts

tests/networkxml2confdata/nat-network.conf

@@ -10,6 +10,7 @@ bind-dynamic
 interface=virbr0
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile
 addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts

tests/networkxml2confdata/netboot-network.conf

@@ -12,6 +12,7 @@ bind-interfaces
 listen-address=192.168.122.1
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 enable-tftp
 tftp-root=/var/lib/tftproot
 dhcp-boot=pxeboot.img

tests/networkxml2confdata/netboot-proxy-network.conf

@@ -12,6 +12,7 @@ bind-interfaces
 listen-address=192.168.122.1
 dhcp-range=192.168.122.2,192.168.122.254
 dhcp-no-override
+dhcp-authoritative
 dhcp-boot=pxeboot.img,,10.20.30.40
 dhcp-lease-max=253
 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/netboot.hostsfile