qemu: Implement usernet address

https://bugzilla.redhat.com/show_bug.cgi?id=1075520

Apart from generic checks, we need to constrain netmask/prefix
length a bit. Thing is, with current implementation QEMU needs to
be able to 'assign' some IP addresses to the virtual network. For
instance, the default gateway is at x.x.x.2, dns is at x.x.x.3,
the default DHCP range is x.x.x.15-x.x.x.30. Since we don't
expose these settings yet, it's safer to require shorter prefix
to have room for the defaults.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: laine@laine.org

src/qemu/qemu_command.c

@@ -3805,6 +3805,7 @@ qemuBuildHostNetStr(virDomainNetDefPtr net,
     virDomainNetType netType = virDomainNetGetActualType(net);
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     size_t i;
+    char *addr = NULL;
     char *ret = NULL;
 
     if (net->script && netType != VIR_DOMAIN_NET_TYPE_ETHERNET) {
@@ -3873,6 +3874,26 @@ qemuBuildHostNetStr(virDomainNetDefPtr net,
         break;
 
     case VIR_DOMAIN_NET_TYPE_USER:
+        virBufferAsprintf(&buf, "user%c", type_sep);
+        for (i = 0; i < net->guestIP.nips; i++) {
+            const virNetDevIPAddr *ip = net->guestIP.ips[i];
+            const char *prefix = "";
+
+            if (!(addr = virSocketAddrFormat(&ip->address)))
+                goto cleanup;
+
+            if (VIR_SOCKET_ADDR_IS_FAMILY(&ip->address, AF_INET))
+                prefix = "net=";
+            if (VIR_SOCKET_ADDR_IS_FAMILY(&ip->address, AF_INET6))
+                prefix = "ipv6-net=";
+
+            virBufferAsprintf(&buf, "%s%s", prefix, addr);
+            if (ip->prefix)
+                virBufferAsprintf(&buf, "/%u", ip->prefix);
+            virBufferAddChar(&buf, ',');
+        }
+        break;
+
     case VIR_DOMAIN_NET_TYPE_INTERNAL:
         virBufferAsprintf(&buf, "user%c", type_sep);
         break;
@@ -3928,6 +3949,7 @@ qemuBuildHostNetStr(virDomainNetDefPtr net,
  cleanup:
     virBufferFreeAndReset(&buf);
     virObjectUnref(cfg);
+    VIR_FREE(addr);
     return ret;
 }
 

src/qemu/qemu_domain.c

@@ -3338,9 +3338,11 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
                             void *opaque ATTRIBUTE_UNUSED)
 {
     int ret = -1;
+    size_t i;
 
     if (dev->type == VIR_DOMAIN_DEVICE_NET) {
         const virDomainNetDef *net = dev->data.net;
+        bool hasIPv4 = false, hasIPv6 = false;
 
         if (net->type == VIR_DOMAIN_NET_TYPE_USER) {
             if (net->guestIP.nroutes) {
@@ -3349,6 +3351,48 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
                                  "guest-side IP route, not supported by QEMU"));
                 goto cleanup;
             }
+
+            for (i = 0; i < net->guestIP.nips; i++) {
+                const virNetDevIPAddr *ip = net->guestIP.ips[i];
+
+                if (VIR_SOCKET_ADDR_VALID(&net->guestIP.ips[i]->peer)) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                                   _("Invalid attempt to set peer IP for guest"));
+                    goto cleanup;
+                }
+
+                if (VIR_SOCKET_ADDR_IS_FAMILY(&ip->address, AF_INET)) {
+                    if (hasIPv4) {
+                        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                                       _("Only one IPv4 address per "
+                                         "interface is allowed"));
+                        goto cleanup;
+                    }
+                    hasIPv4 = true;
+
+                    if (ip->prefix > 27) {
+                        virReportError(VIR_ERR_XML_ERROR, "%s",
+                                       _("prefix too long"));
+                        goto cleanup;
+                    }
+                }
+
+                if (VIR_SOCKET_ADDR_IS_FAMILY(&ip->address, AF_INET6)) {
+                    if (hasIPv6) {
+                        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                                       _("Only one IPv6 address per "
+                                         "interface is allowed"));
+                        goto cleanup;
+                    }
+                    hasIPv6 = true;
+
+                    if (ip->prefix > 120) {
+                        virReportError(VIR_ERR_XML_ERROR, "%s",
+                                       _("prefix too long"));
+                        goto cleanup;
+                    }
+                }
+            }
         } else if (net->guestIP.nroutes || net->guestIP.nips) {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                            _("Invalid attempt to set network interface "

tests/qemuxml2argvdata/qemuxml2argv-net-user-addr.args

@@ -0,0 +1,26 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-i686 \
+-name QEMUGuest1 \
+-S \
+-M pc \
+-m 214 \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-nographic \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=readline \
+-no-acpi \
+-boot c \
+-usb \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0 \
+-device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
+-netdev user,net=172.17.2.0/24,ipv6-net=2001:db8:ac10:fd01::/64,id=hostnet0 \
+-device rtl8139,netdev=hostnet0,id=net0,mac=00:11:22:33:44:55,bus=pci.0,\
+addr=0x3

tests/qemuxml2argvtest.c

@@ -1161,6 +1161,7 @@ mymain(void)
                     QEMU_CAPS_NETDEV,
                     QEMU_CAPS_VHOSTUSER_MULTIQUEUE);
     DO_TEST("net-user", NONE);
+    DO_TEST("net-user-addr", QEMU_CAPS_NETDEV);
     DO_TEST("net-virtio", NONE);
     DO_TEST("net-virtio-device",
             QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_VIRTIO_TX_ALG);