qemu-process: prepare slirp-helper

When the network interface is of "user" type, and QEMU has the "-net
socket,fd=" datagram support, call qemuInterfacePrepareSlirp() to
probe and associate a slirp-helper with the interface.

The usage of automated slirp-helper can be prevented with
disableSlirp (in particular when resuming a
VM that didn't start with slirp-helper before).

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_interface.c

@@ -612,6 +612,33 @@ qemuInterfaceBridgeConnect(virDomainDefPtr def,
 }
 
 
+qemuSlirpPtr
+qemuInterfacePrepareSlirp(virQEMUDriverPtr driver,
+                          virDomainNetDefPtr net)
+{
+    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    VIR_AUTOPTR(qemuSlirp) slirp = NULL;
+    size_t i;
+
+    if (!(slirp = qemuSlirpNewForHelper(cfg->slirpHelperName)))
+        return NULL;
+
+    for (i = 0; i < net->guestIP.nips; i++) {
+        const virNetDevIPAddr *ip = net->guestIP.ips[i];
+
+        if (VIR_SOCKET_ADDR_IS_FAMILY(&ip->address, AF_INET) &&
+            !qemuSlirpHasFeature(slirp, QEMU_SLIRP_FEATURE_IPV4))
+            return NULL;
+
+        if (VIR_SOCKET_ADDR_IS_FAMILY(&ip->address, AF_INET6) &&
+            !qemuSlirpHasFeature(slirp, QEMU_SLIRP_FEATURE_IPV6))
+            return NULL;
+    }
+
+    VIR_RETURN_PTR(slirp);
+}
+
+
 /**
  * qemuInterfaceOpenVhostNet:
  * @def: domain definition

src/qemu/qemu_interface.h

@@ -24,6 +24,7 @@
 #include "domain_conf.h"
 #include "qemu_conf.h"
 #include "qemu_domain.h"
+#include "qemu_slirp.h"
 
 int qemuInterfaceStartDevice(virDomainNetDefPtr net);
 int qemuInterfaceStartDevices(virDomainDefPtr def);
@@ -54,3 +55,6 @@ int qemuInterfaceOpenVhostNet(virDomainDefPtr def,
                               virDomainNetDefPtr net,
                               int *vhostfd,
                               size_t *vhostfdSize);
+
+qemuSlirpPtr qemuInterfacePrepareSlirp(virQEMUDriverPtr driver,
+                                       virDomainNetDefPtr net);

src/qemu/qemu_process.c

@@ -5705,8 +5705,11 @@ qemuProcessInit(virQEMUDriverPtr driver,
  * qemuProcessNetworkPrepareDevices
  */
 static int
-qemuProcessNetworkPrepareDevices(virDomainDefPtr def)
+qemuProcessNetworkPrepareDevices(virQEMUDriverPtr driver,
+                                 virDomainObjPtr vm)
 {
+    virDomainDefPtr def = vm->def;
+    qemuDomainObjPrivatePtr priv = vm->privateData;
     int ret = -1;
     size_t i;
     virConnectPtr conn = NULL;
@@ -5751,7 +5754,14 @@ qemuProcessNetworkPrepareDevices(virDomainDefPtr def)
             }
             if (virDomainHostdevInsert(def, hostdev) < 0)
                 goto cleanup;
-        }
+        } else if (actualType == VIR_DOMAIN_NET_TYPE_USER &&
+                   !priv->disableSlirp &&
+                   virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_NET_SOCKET_DGRAM)) {
+            qemuSlirpPtr slirp = qemuInterfacePrepareSlirp(driver, net);
+
+            QEMU_DOMAIN_NETWORK_PRIVATE(net)->slirp = slirp;
+         }
+
     }
     ret = 0;
  cleanup:
@@ -6552,7 +6562,7 @@ qemuProcessPrepareHost(virQEMUDriverPtr driver,
      * will need to be setup.
      */
     VIR_DEBUG("Preparing network devices");
-    if (qemuProcessNetworkPrepareDevices(vm->def) < 0)
+    if (qemuProcessNetworkPrepareDevices(driver, vm) < 0)
         goto cleanup;
 
     /* Must be run before security labelling */