interface: add udev based backend for virInterface

Add a read-only udev based backend for virInterface. Useful for distros
that do not have netcf support yet. Multiple libvirt based utilities use
a HAL based fallback when virInterface is not available which is less
than ideal. This implements:
* virConnectNumOfInterfaces()
* virConnectListInterfaces()
* virConnectNumOfDefinedInterfaces()
* virConnectListDefinedInterfaces()
* virConnectListAllInterfaces()
* virConnectInterfaceLookupByName()
* virConnectInterfaceLookupByMACString()

configure.ac

@@ -2809,18 +2809,12 @@ if test "$with_libvirtd" = "no" ; then
   with_interface=no
 fi
 
-dnl The interface driver depends on the netcf library
-if test "$with_interface:$with_netcf" = "check:yes" ; then
-  with_interface=yes
-fi
-
-if test "$with_interface:$with_netcf" = "check:no" ; then
-  with_interface=no
-fi
-
-if test "$with_interface:$with_netcf" = "yes:no" ; then
-  AC_MSG_ERROR([Requested the Interface driver without netcf support])
-fi
+dnl The interface driver depends on the netcf library or udev library
+case $with_interface:$with_netcf:$with_udev in
+    check:*yes*) with_interface=yes ;;
+    check:no:no) with_interface=no ;;
+    yes:no:no) AC_MSG_ERROR([Requested the Interface driver without netcf or udev support]) ;;
+esac
 
 if test "$with_interface" = "yes" ; then
   AC_DEFINE_UNQUOTED([WITH_INTERFACE], [1],

po/POTFILES.in

@@ -41,6 +41,7 @@ src/hyperv/hyperv_driver.c
 src/hyperv/hyperv_util.c
 src/hyperv/hyperv_wmi.c
 src/interface/interface_backend_netcf.c
+src/interface/interface_backend_udev.c
 src/internal.h
 src/libvirt.c
 src/libvirt-qemu.c

src/Makefile.am

@@ -558,11 +558,16 @@ INTERFACE_DRIVER_SOURCES =
 if WITH_INTERFACE
 INTERFACE_DRIVER_SOURCES +=					\
 		interface/interface_driver.h
-endif
 
 if WITH_NETCF
 INTERFACE_DRIVER_SOURCES +=					\
 		interface/interface_backend_netcf.c
+else
+if HAVE_UDEV
+INTERFACE_DRIVER_SOURCES +=					\
+		interface/interface_backend_udev.c
+endif
+endif
 endif
 
 SECRET_DRIVER_SOURCES =						\
@@ -1045,6 +1050,11 @@ libvirt_driver_interface_la_LIBADD =
 if WITH_NETCF
 libvirt_driver_interface_la_CFLAGS += $(NETCF_CFLAGS)
 libvirt_driver_interface_la_LIBADD += $(NETCF_LIBS)
+else
+if HAVE_UDEV
+libvirt_driver_interface_la_CFLAGS += $(UDEV_CFLAGS)
+libvirt_driver_interface_la_LIBADD += $(UDEV_LIBS)
+endif
 endif
 if WITH_DRIVER_MODULES
 libvirt_driver_interface_la_LIBADD += ../gnulib/lib/libgnu.la

src/interface/interface_backend_udev.c

+/*
+ * interface_backend_udev.c: udev backend for virInterface
+ *
+ * Copyright (C) 2012 Doug Goldstein <cardoe@cardoe.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library;  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+#include <config.h>
+
+#include <libudev.h>
+
+#include "virterror_internal.h"
+#include "datatypes.h"
+#include "interface_driver.h"
+#include "interface_conf.h"
+#include "memory.h"
+
+#define VIR_FROM_THIS VIR_FROM_INTERFACE
+
+struct udev_iface_driver {
+    struct udev *udev;
+};
+
+typedef enum {
+    VIR_UDEV_IFACE_ACTIVE,
+    VIR_UDEV_IFACE_INACTIVE,
+    VIR_UDEV_IFACE_ALL
+} virUdevStatus ;
+
+static const char *
+virUdevStatusString(virUdevStatus status)
+{
+    switch (status) {
+        case VIR_UDEV_IFACE_ACTIVE:
+            return "active";
+        case VIR_UDEV_IFACE_INACTIVE:
+            return "inactive";
+        case VIR_UDEV_IFACE_ALL:
+            return "all";
+    }
+
+    return "";
+}
+
+static struct udev_enumerate * ATTRIBUTE_NONNULL(1)
+udevIfaceGetDevices(struct udev *udev, virUdevStatus status)
+{
+    struct udev_enumerate *enumerate;
+
+    /* Create a new enumeration to create a list */
+    enumerate = udev_enumerate_new(udev);
+
+    if (!enumerate)
+        return NULL;
+
+    /* Enumerate all network subsystem devices */
+    udev_enumerate_add_match_subsystem(enumerate, "net");
+
+    /* Ignore devices that are part of a bridge */
+    udev_enumerate_add_nomatch_sysattr(enumerate, "brport/state", NULL);
+
+    /* State of the device */
+    switch (status) {
+        case VIR_UDEV_IFACE_ACTIVE:
+            udev_enumerate_add_match_sysattr(enumerate, "operstate", "up");
+            break;
+
+        case VIR_UDEV_IFACE_INACTIVE:
+            udev_enumerate_add_match_sysattr(enumerate, "operstate", "down");
+            break;
+
+        case VIR_UDEV_IFACE_ALL:
+            break;
+    }
+
+    /* We don't want to see the TUN devices that QEMU creates for other guests
+     * running on this machine. By saying nomatch NULL, we just are getting
+     * devices without the tun_flags sysattr.
+     */
+    udev_enumerate_add_nomatch_sysattr(enumerate, "tun_flags", NULL);
+
+    return enumerate;
+}
+
+static virDrvOpenStatus
+udevIfaceOpenInterface(virConnectPtr conn,
+                       virConnectAuthPtr auth ATTRIBUTE_UNUSED,
+                       unsigned int flags)
+{
+    struct udev_iface_driver *driverState = NULL;
+
+    virCheckFlags(0, VIR_DRV_OPEN_ERROR);
+
+    if (VIR_ALLOC(driverState) < 0) {
+        virReportOOMError();
+        goto err;
+    }
+
+    driverState->udev = udev_new();
+    if (!driverState->udev) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("failed to create udev context"));
+        goto err;
+    }
+
+    conn->interfacePrivateData = driverState;
+
+    return VIR_DRV_OPEN_SUCCESS;
+
+err:
+    VIR_FREE(driverState);
+
+    return VIR_DRV_OPEN_ERROR;
+}
+
+static int
+udevIfaceCloseInterface(virConnectPtr conn)
+{
+    struct udev_iface_driver *driverState;
+
+    if (conn->interfacePrivateData != NULL) {
+        driverState = conn->interfacePrivateData;
+
+        udev_unref(driverState->udev);
+
+        VIR_FREE(driverState);
+    }
+
+    conn->interfacePrivateData = NULL;
+    return 0;
+}
+
+static int
+udevIfaceNumOfInterfacesByStatus(virConnectPtr conn, virUdevStatus status)
+{
+    struct udev_iface_driver *driverState = conn->interfacePrivateData;
+    struct udev *udev = udev_ref(driverState->udev);
+    struct udev_enumerate *enumerate = NULL;
+    struct udev_list_entry *devices;
+    struct udev_list_entry *dev_entry;
+    int count = 0;
+
+    enumerate = udevIfaceGetDevices(udev, status);
+
+    if (!enumerate) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("failed to get number of %s interfaces on host"),
+                       virUdevStatusString(status));
+        count = -1;
+        goto err;
+    }
+
+    /* Do the scan to load up the enumeration */
+    udev_enumerate_scan_devices(enumerate);
+
+    /* Get a list we can walk */
+    devices = udev_enumerate_get_list_entry(enumerate);
+
+    /* For each item so we can count */
+    udev_list_entry_foreach(dev_entry, devices) {
+        count++;
+    }
+
+err:
+    if (enumerate)
+        udev_enumerate_unref(enumerate);
+    udev_unref(udev);
+
+    return count;
+}
+
+static int
+udevIfaceListInterfacesByStatus(virConnectPtr conn,
+                                char **const names,
+                                int names_len,
+                                virUdevStatus status)
+{
+    struct udev_iface_driver *driverState = conn->interfacePrivateData;
+    struct udev *udev = udev_ref(driverState->udev);
+    struct udev_enumerate *enumerate = NULL;
+    struct udev_list_entry *devices;
+    struct udev_list_entry *dev_entry;
+    int count = 0;
+
+    enumerate = udevIfaceGetDevices(udev, status);
+
+    if (!enumerate) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("failed to get list of %s interfaces on host"),
+                       virUdevStatusString(status));
+        goto err;
+    }
+
+    /* Do the scan to load up the enumeration */
+    udev_enumerate_scan_devices(enumerate);
+
+    /* Get a list we can walk */
+    devices = udev_enumerate_get_list_entry(enumerate);
+
+    /* For each item so we can count */
+    udev_list_entry_foreach(dev_entry, devices) {
+        struct udev_device *dev;
+        const char *path;
+
+        /* Ensure we won't exceed the size of our array */
+        if (count > names_len)
+            break;
+
+        path = udev_list_entry_get_name(dev_entry);
+        dev = udev_device_new_from_syspath(udev, path);
+        names[count] = strdup(udev_device_get_sysname(dev));
+        udev_device_unref(dev);
+
+        /* If strdup() failed, we are out of memory */
+        if (!names[count]) {
+            virReportOOMError();
+            goto err;
+        }
+
+        count++;
+    }
+
+    udev_enumerate_unref(enumerate);
+    udev_unref(udev);
+
+    return count;
+
+err:
+    if (enumerate)
+        udev_enumerate_unref(enumerate);
+    udev_unref(udev);
+
+    for (names_len = 0; names_len < count; names_len++)
+        VIR_FREE(names[names_len]);
+
+    return -1;
+}
+
+static int
+udevIfaceNumOfInterfaces(virConnectPtr conn)
+{
+    return udevIfaceNumOfInterfacesByStatus(conn, VIR_UDEV_IFACE_ACTIVE);
+}
+
+static int
+udevIfaceListInterfaces(virConnectPtr conn,
+                        char **const names,
+                        int names_len)
+{
+    return udevIfaceListInterfacesByStatus(conn, names, names_len,
+                                           VIR_UDEV_IFACE_ACTIVE);
+}
+
+static int
+udevIfaceNumOfDefinedInterfaces(virConnectPtr conn)
+{
+    return udevIfaceNumOfInterfacesByStatus(conn, VIR_UDEV_IFACE_INACTIVE);
+}
+
+static int
+udevIfaceListDefinedInterfaces(virConnectPtr conn,
+                               char **const names,
+                               int names_len)
+{
+    return udevIfaceListInterfacesByStatus(conn, names, names_len,
+                                           VIR_UDEV_IFACE_INACTIVE);
+}
+
+static int
+udevIfaceListAllInterfaces(virConnectPtr conn,
+                           virInterfacePtr **ifaces,
+                           unsigned int flags)
+{
+    struct udev_iface_driver *driverState = conn->interfacePrivateData;
+    struct udev *udev;
+    struct udev_enumerate *enumerate = NULL;
+    struct udev_list_entry *devices;
+    struct udev_list_entry *dev_entry;
+    virInterfacePtr *ifaces_list;
+    virInterfacePtr iface_obj;
+    int tmp_count;
+    int count = 0;
+    int status = 0;
+    int ret;
+
+    virCheckFlags(VIR_CONNECT_LIST_INTERFACES_ACTIVE |
+                  VIR_CONNECT_LIST_INTERFACES_INACTIVE, -1);
+
+    /* Grab a udev reference */
+    udev = udev_ref(driverState->udev);
+
+    /* List all interfaces in case we support more filter flags in the future */
+    enumerate = udevIfaceGetDevices(udev, VIR_UDEV_IFACE_ALL);
+
+    if (!enumerate) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("failed to get list of %s interfaces on host"),
+                       virUdevStatusString(status));
+        ret = -1;
+        goto cleanup;
+    }
+
+    /* Do the scan to load up the enumeration */
+    udev_enumerate_scan_devices(enumerate);
+
+    /* Get a list we can walk */
+    devices = udev_enumerate_get_list_entry(enumerate);
+
+    /* For each item so we can count */
+    udev_list_entry_foreach(dev_entry, devices) {
+        count++;
+    }
+
+    /* If we've got nothing, exit out */
+    if (count == 0) {
+        ret = 0;
+        goto cleanup;
+    }
+
+    /* If we're asked for the ifaces then alloc up memory */
+    if (ifaces) {
+        if (VIR_ALLOC_N(ifaces_list, count + 1) < 0) {
+            virReportOOMError();
+            ret = -1;
+            goto cleanup;
+        }
+    }
+
+    /* Get a list we can walk */
+    devices = udev_enumerate_get_list_entry(enumerate);
+
+    /* reset our iterator */
+    count = 0;
+
+    /* Walk through each device */
+    udev_list_entry_foreach(dev_entry, devices) {
+        struct udev_device *dev;
+        const char *path;
+        const char *name;
+        const char *macaddr;
+        int add_to_list;
+
+        path = udev_list_entry_get_name(dev_entry);
+        dev = udev_device_new_from_syspath(udev, path);
+        name = udev_device_get_sysname(dev);
+        macaddr = udev_device_get_sysattr_value(dev, "address");
+        status = STREQ(udev_device_get_sysattr_value(dev, "operstate"), "up");
+        udev_device_unref(dev);
+
+        /* Filter the results */
+        if (status && (flags & VIR_CONNECT_LIST_INTERFACES_ACTIVE))
+            add_to_list = 1;
+        else if (!status && (flags & VIR_CONNECT_LIST_INTERFACES_INACTIVE))
+            add_to_list = 1;
+
+        /* If we matched a filter, then add it */
+        if (add_to_list) {
+            if (ifaces) {
+                iface_obj = virGetInterface(conn, name, macaddr);
+                ifaces_list[count] = iface_obj;
+            }
+            count++;
+        }
+    }
+
+    /* Drop our refcounts */
+    udev_enumerate_unref(enumerate);
+    udev_unref(udev);
+
+    /* Trim the array to its final size */
+    if (ifaces) {
+        ignore_value(VIR_REALLOC_N(ifaces_list, count + 1));
+        *ifaces = ifaces_list;
+    }
+
+    return count;
+
+cleanup:
+    if (enumerate)
+        udev_enumerate_unref(enumerate);
+    udev_unref(udev);
+
+    if (ifaces) {
+        for (tmp_count = 0; tmp_count < count; tmp_count++)
+            virInterfaceFree(ifaces_list[tmp_count]);
+    }
+
+    VIR_FREE(ifaces_list);
+
+    return ret;
+
+}
+
+static virInterfacePtr
+udevIfaceLookupByName(virConnectPtr conn, const char *name)
+{
+    struct udev_iface_driver *driverState = conn->interfacePrivateData;
+    struct udev *udev = udev_ref(driverState->udev);
+    struct udev_device *dev;
+    const char *macaddr;
+    virInterfacePtr ret = NULL;
+
+    /* get a device reference based on the device name */
+    dev = udev_device_new_from_subsystem_sysname(udev, "net", name);
+    if (!dev) {
+        virReportError(VIR_ERR_NO_INTERFACE,
+                       _("couldn't find interface named '%s'"),
+                       name);
+        goto err;
+    }
+
+    macaddr = udev_device_get_sysattr_value(dev, "address");
+    ret = virGetInterface(conn, name, macaddr);
+    udev_device_unref(dev);
+
+err:
+    udev_unref(udev);
+
+    return ret;
+}
+
+static virInterfacePtr
+udevIfaceLookupByMACString(virConnectPtr conn, const char *macstr)
+{
+    struct udev_iface_driver *driverState = conn->interfacePrivateData;
+    struct udev *udev = udev_ref(driverState->udev);
+    struct udev_enumerate *enumerate = NULL;
+    struct udev_list_entry *dev_entry;
+    struct udev_device *dev;
+    const char *name;
+    virInterfacePtr ret = NULL;
+
+    enumerate = udevIfaceGetDevices(udev, VIR_UDEV_IFACE_ALL);
+
+    if (!enumerate) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("failed to lookup interface with MAC address '%s'"),
+                       macstr);
+        goto err;
+    }
+
+    /* Match on MAC */
+    udev_enumerate_add_match_sysattr(enumerate, "address", macstr);
+
+    /* Do the scan to load up the enumeration */
+    udev_enumerate_scan_devices(enumerate);
+
+    /* Get a list we can walk */
+    dev_entry = udev_enumerate_get_list_entry(enumerate);
+
+    /* Check that we got something back */
+    if (!dev_entry) {
+        virReportError(VIR_ERR_NO_INTERFACE,
+                       _("couldn't find interface with MAC address '%s'"),
+                       macstr);
+        goto err;
+    }
+
+    /* Check that we didn't get multiple items back */
+    if (udev_list_entry_get_next(dev_entry)) {
+        virReportError(VIR_ERR_MULTIPLE_INTERFACES,
+                       _("the MAC address '%s' matches multiple interfaces"),
+                       macstr);
+        goto err;
+    }
+
+    dev = udev_device_new_from_syspath(udev, udev_list_entry_get_name(dev_entry));
+    name = udev_device_get_sysname(dev);
+    ret = virGetInterface(conn, name, macstr);
+    udev_device_unref(dev);
+
+err:
+    if (enumerate)
+        udev_enumerate_unref(enumerate);
+    udev_unref(udev);
+
+    return ret;
+}
+
+static virInterfaceDriver udevIfaceDriver = {
+    "udev",
+    .open = udevIfaceOpenInterface, /* 0.10.3 */
+    .close = udevIfaceCloseInterface, /* 0.10.3 */
+    .numOfInterfaces = udevIfaceNumOfInterfaces, /* 0.10.3 */
+    .listInterfaces = udevIfaceListInterfaces, /* 0.10.3 */
+    .numOfDefinedInterfaces = udevIfaceNumOfDefinedInterfaces, /* 0.10.3 */
+    .listDefinedInterfaces = udevIfaceListDefinedInterfaces, /* 0.10.3 */
+    .listAllInterfaces = udevIfaceListAllInterfaces, /* 0.10.3 */
+    .interfaceLookupByName = udevIfaceLookupByName, /* 0.10.3 */
+    .interfaceLookupByMACString = udevIfaceLookupByMACString, /* 0.10.3 */
+};
+
+int
+interfaceRegister(void) {
+    if (virRegisterInterfaceDriver(&udevIfaceDriver) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("failed to register udev interface driver"));
+        return -1;
+    }
+    return 0;
+}

tools/virsh.c

@@ -2708,6 +2708,8 @@ vshShowVersion(vshControl *ctl ATTRIBUTE_UNUSED)
     vshPrint(ctl, " Interface");
 # if defined(WITH_NETCF)
     vshPrint(ctl, " netcf");
+# elif defined(HAVE_UDEV)
+    vshPrint(ctl, " udev");
 # endif
 #endif
 #ifdef WITH_NWFILTER