util: Introduce helper functions for generating unique netdev name

Extract ReserveName/GenerateName from netdevtap and netdevmacvlan as
common helper functions.

Signed-off-by: Shi Lei <shi_lei@massclouds.com>
Reviewed-by: Laine Stump <laine@redhat.com>

diff --git a/src/bhyve/bhyve_command.c b/src/bhyve/bhyve_command.c
index acf3a5a43320185338f8f7436c05e94bf9ed75e1..4cf98c0eb1c987e962328053e89103512cd21eb7 100644 (file)
--- a/src/bhyve/bhyve_command.c
+++ b/src/bhyve/bhyve_command.c
@@ -80,10 +80,10 @@ bhyveBuildNetArgStr(const virDomainDef *def,
     }
 
     if (!net->ifname ||
-        STRPREFIX(net->ifname, VIR_NET_GENERATED_TAP_PREFIX) ||
+        STRPREFIX(net->ifname, VIR_NET_GENERATED_VNET_PREFIX) ||
         strchr(net->ifname, '%')) {
         VIR_FREE(net->ifname);
-        net->ifname = g_strdup(VIR_NET_GENERATED_TAP_PREFIX "%d");
+        net->ifname = g_strdup(VIR_NET_GENERATED_VNET_PREFIX "%d");
     }
 
     if (!dryRun) {

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 26c48ef38cb33b73b816288afb91b6349072a96d..b301ac0a0818a4b0108680dc8e334a3b71e299b1 100644 (file)
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -11081,7 +11081,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
 
     if (def->managed_tap != VIR_TRISTATE_BOOL_NO && ifname &&
         (flags & VIR_DOMAIN_DEF_PARSE_INACTIVE) &&
-        (STRPREFIX(ifname, VIR_NET_GENERATED_TAP_PREFIX) ||
+        (STRPREFIX(ifname, VIR_NET_GENERATED_VNET_PREFIX) ||
          STRPREFIX(ifname, VIR_NET_GENERATED_MACVTAP_PREFIX) ||
          STRPREFIX(ifname, VIR_NET_GENERATED_MACVLAN_PREFIX) ||
          (prefix && STRPREFIX(ifname, prefix)))) {
@@ -25504,7 +25504,7 @@ virDomainNetDefFormat(virBufferPtr buf,
     if (def->ifname &&
         (def->managed_tap == VIR_TRISTATE_BOOL_NO ||
          !((flags & VIR_DOMAIN_DEF_FORMAT_INACTIVE) &&
-           (STRPREFIX(def->ifname, VIR_NET_GENERATED_TAP_PREFIX) ||
+           (STRPREFIX(def->ifname, VIR_NET_GENERATED_VNET_PREFIX) ||
             STRPREFIX(def->ifname, VIR_NET_GENERATED_MACVTAP_PREFIX) ||
             STRPREFIX(def->ifname, VIR_NET_GENERATED_MACVLAN_PREFIX) ||
             (prefix && STRPREFIX(def->ifname, prefix)))))) {

diff --git a/src/interface/interface_backend_udev.c b/src/interface/interface_backend_udev.c
index 173c4fc3f09411ecfdfb70e99c537d9065ce0eb1..6a94a4504467acb5bca866d76907b207f18fda9d 100644 (file)
--- a/src/interface/interface_backend_udev.c
+++ b/src/interface/interface_backend_udev.c
@@ -544,7 +544,7 @@ udevBridgeScanDirFilter(const struct dirent *entry)
      * vnet%d. Improvements to this check are welcome.
      */
     if (strlen(entry->d_name) >= 5) {
-        if (STRPREFIX(entry->d_name, VIR_NET_GENERATED_TAP_PREFIX) &&
+        if (STRPREFIX(entry->d_name, VIR_NET_GENERATED_VNET_PREFIX) &&
             g_ascii_isdigit(entry->d_name[4]))
             return 0;
     }

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index d0e548b0a369fc4394fe37532be5e00c3d66d589..77c8e4aaee9d165bc80250217ba43589d2302420 100644 (file)
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2554,6 +2554,7 @@ virNetDevDelMulti;
 virNetDevExists;
 virNetDevFeatureTypeFromString;
 virNetDevFeatureTypeToString;
+virNetDevGenerateName;
 virNetDevGetFeatures;
 virNetDevGetIndex;
 virNetDevGetLinkInfo;
@@ -2577,6 +2578,7 @@ virNetDevIfStateTypeToString;
 virNetDevIsVirtualFunction;
 virNetDevPFGetVF;
 virNetDevReadNetConfig;
+virNetDevReserveName;
 virNetDevRunEthernetScript;
 virNetDevRxFilterFree;
 virNetDevRxFilterModeTypeFromString;

diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c
index 32b397d28f6b4e7533be372af6ef7fb4dfc8dfd2..197c0aa239e3e382eedb9f495346f20174aee8ba 100644 (file)
--- a/src/qemu/qemu_interface.c
+++ b/src/qemu/qemu_interface.c
@@ -456,10 +456,10 @@ qemuInterfaceEthernetConnect(virDomainDefPtr def,
         }
     } else {
         if (!net->ifname ||
-            STRPREFIX(net->ifname, VIR_NET_GENERATED_TAP_PREFIX) ||
+            STRPREFIX(net->ifname, VIR_NET_GENERATED_VNET_PREFIX) ||
             strchr(net->ifname, '%')) {
             VIR_FREE(net->ifname);
-            net->ifname = g_strdup(VIR_NET_GENERATED_TAP_PREFIX "%d");
+            net->ifname = g_strdup(VIR_NET_GENERATED_VNET_PREFIX "%d");
             /* avoid exposing vnet%d in getXMLDesc or error outputs */
             template_ifname = true;
         }
@@ -560,10 +560,10 @@ qemuInterfaceBridgeConnect(virDomainDefPtr def,
     }
 
     if (!net->ifname ||
-        STRPREFIX(net->ifname, VIR_NET_GENERATED_TAP_PREFIX) ||
+        STRPREFIX(net->ifname, VIR_NET_GENERATED_VNET_PREFIX) ||
         strchr(net->ifname, '%')) {
         VIR_FREE(net->ifname);
-        net->ifname = g_strdup(VIR_NET_GENERATED_TAP_PREFIX "%d");
+        net->ifname = g_strdup(VIR_NET_GENERATED_VNET_PREFIX "%d");
         /* avoid exposing vnet%d in getXMLDesc or error outputs */
         template_ifname = true;
     }

diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index 5104bbe7c52d7f92d46334ad2ea7a37b21a0511f..a73e5f72f1f03283f94fe58494d0134966046830 100644 (file)
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -17,6 +17,7 @@
  */
 
 #include <config.h>
+#include <math.h>
 
 #include "virnetdev.h"
 #include "viralloc.h"
@@ -95,6 +96,14 @@ VIR_LOG_INIT("util.netdev");
     (FEATURE_WORD(blocks, index, field) & FEATURE_FIELD_FLAG(index))
 #endif
 
+
+static virNetDevGenName
+virNetDevGenNames[VIR_NET_DEV_GEN_NAME_LAST] = {
+    {-1, VIR_NET_GENERATED_VNET_PREFIX, VIR_MUTEX_INITIALIZER},
+    {-1, VIR_NET_GENERATED_MACVTAP_PREFIX, VIR_MUTEX_INITIALIZER},
+    {-1, VIR_NET_GENERATED_MACVLAN_PREFIX, VIR_MUTEX_INITIALIZER},
+};
+
 typedef enum {
     VIR_MCAST_TYPE_INDEX_TOKEN,
     VIR_MCAST_TYPE_NAME_TOKEN,
@@ -3516,3 +3525,116 @@ virNetDevSetRootQDisc(const char *ifname,
 
     return 0;
 }
+
+
+/**
+ * virNetDevReserveName:
+ * @name: name of an existing network device
+ *
+ * Reserve a network device name, so that any new network device
+ * created with an autogenerated name will use a number higher
+ * than the number in the given device name.
+ *
+ * Returns nothing.
+ */
+void
+virNetDevReserveName(const char *name)
+{
+    unsigned int id;
+    const char *idstr = NULL;
+    virNetDevGenNameType type;
+
+    if (!name)
+        return;
+
+    if (STRPREFIX(name, VIR_NET_GENERATED_VNET_PREFIX))
+        type = VIR_NET_DEV_GEN_NAME_VNET;
+    else if (STRPREFIX(name, VIR_NET_GENERATED_MACVTAP_PREFIX))
+        type = VIR_NET_DEV_GEN_NAME_MACVTAP;
+    else if (STRPREFIX(name, VIR_NET_GENERATED_MACVLAN_PREFIX))
+        type = VIR_NET_DEV_GEN_NAME_MACVLAN;
+    else
+        return;
+
+    VIR_INFO("marking device in use: '%s'", name);
+
+    idstr = name + strlen(virNetDevGenNames[type].prefix);
+
+    if (virStrToLong_ui(idstr, NULL, 10, &id) >= 0) {
+        virMutexLock(&virNetDevGenNames[type].mutex);
+
+        if (virNetDevGenNames[type].lastID < (int)id)
+            virNetDevGenNames[type].lastID = id;
+
+        virMutexUnlock(&virNetDevGenNames[type].mutex);
+    }
+}
+
+
+/**
+ * virNetDevGenerateName:
+ * @ifname: pointer to pointer to string which can be a template,
+ *          NULL or user-provided name.
+ * @type: type of the network device
+ *
+ * generate a new (currently unused) name for a new network device based
+ * on @ifname. If string pointed by @ifname is a template, replace %d
+ * with the reserved id; if that string is NULL, just generate a new
+ * name. Keep trying new values until one is found that doesn't already
+ * exist, or we've tried 10000 different names. Once a usable name is
+ * found, replace the template with the actual name.
+ *
+ * Note: if string pointed by @ifname is NOT a template or NULL, leave
+ * it unchanged and return it directly.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+int
+virNetDevGenerateName(char **ifname, virNetDevGenNameType type)
+{
+    int id;
+    const char *prefix = virNetDevGenNames[type].prefix;
+    double maxIDd = pow(10, IFNAMSIZ - 1 - strlen(prefix));
+    int maxID = INT_MAX;
+    int attempts = 0;
+
+    /* The @ifname is not a template, leave it unchanged. */
+    if (*ifname &&
+        (strchr(*ifname, '%') != strrchr(*ifname, '%') ||
+         strstr(*ifname, "%d") == NULL)) {
+        return 0;
+    }
+
+    if (maxIDd <= (double)INT_MAX)
+        maxID = (int)maxIDd;
+
+    do {
+        g_autofree char *try = NULL;
+
+        virMutexLock(&virNetDevGenNames[type].mutex);
+
+        id = ++virNetDevGenNames[type].lastID;
+
+        /* reset before overflow */
+        if (virNetDevGenNames[type].lastID >= maxID)
+            virNetDevGenNames[type].lastID = -1;
+
+        virMutexUnlock(&virNetDevGenNames[type].mutex);
+
+        if (*ifname)
+            try = g_strdup_printf(*ifname, id);
+        else
+            try = g_strdup_printf("%s%d", prefix, id);
+
+        if (!virNetDevExists(try)) {
+            g_free(*ifname);
+            *ifname = g_steal_pointer(&try);
+            return 0;
+        }
+    } while (++attempts < 10000);
+
+    virReportError(VIR_ERR_INTERNAL_ERROR,
+                   _("no unused %s names available"),
+                   prefix);
+    return -1;
+}

diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h
index 53e606c61cb7bcdd5a94f537d161f3489d14e835..f01601271880909cc987978e3241942ca583e670 100644 (file)
--- a/src/util/virnetdev.h
+++ b/src/util/virnetdev.h
@@ -38,7 +38,13 @@ typedef void virIfreq;
 /* Used for prefix of ifname of any tap device name generated
  * dynamically by libvirt, cannot be used for a persistent network name.
  */
-#define VIR_NET_GENERATED_TAP_PREFIX "vnet"
+#define VIR_NET_GENERATED_VNET_PREFIX "vnet"
+
+/* libvirt will start macvtap/macvlan interface names with one of
+ * these prefixes when it auto-generates the name
+ */
+#define VIR_NET_GENERATED_MACVTAP_PREFIX "macvtap"
+#define VIR_NET_GENERATED_MACVLAN_PREFIX "macvlan"
 
 typedef enum {
    VIR_NETDEV_RX_FILTER_MODE_NONE = 0,
@@ -145,6 +151,21 @@ struct _virNetDevCoalesce {
     uint32_t rate_sample_interval;
 };
 
+typedef enum {
+    VIR_NET_DEV_GEN_NAME_VNET,
+    VIR_NET_DEV_GEN_NAME_MACVTAP,
+    VIR_NET_DEV_GEN_NAME_MACVLAN,
+    VIR_NET_DEV_GEN_NAME_LAST
+} virNetDevGenNameType;
+
+typedef struct _virNetDevGenName virNetDevGenName;
+typedef virNetDevGenName *virNetDevGenNamePtr;
+struct _virNetDevGenName {
+    int lastID;         /* not "unsigned" because callers use %d */
+    const char *prefix;
+    virMutex mutex;
+};
+
 
 int virNetDevSetupControl(const char *ifname,
                           virIfreq *ifr)
@@ -321,3 +342,7 @@ int virNetDevVFInterfaceStats(virPCIDeviceAddressPtr vfAddr,
 ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(virNetDevRxFilter, virNetDevRxFilterFree);
+
+void virNetDevReserveName(const char *name);
+
+int virNetDevGenerateName(char **ifname, virNetDevGenNameType type);

diff --git a/src/util/virnetdevtap.c b/src/util/virnetdevtap.c
index 198607b5bb4a82c906d3b067745dea95fdd6e6a6..9354cc10e4168aeb887d739e01e29057041371c0 100644 (file)
--- a/src/util/virnetdevtap.c
+++ b/src/util/virnetdevtap.c
@@ -76,11 +76,11 @@ virNetDevTapReserveName(const char *name)
     const char *idstr = NULL;
 
 
-    if (STRPREFIX(name, VIR_NET_GENERATED_TAP_PREFIX)) {
+    if (STRPREFIX(name, VIR_NET_GENERATED_VNET_PREFIX)) {
 
         VIR_INFO("marking device in use: '%s'", name);
 
-        idstr = name + strlen(VIR_NET_GENERATED_TAP_PREFIX);
+        idstr = name + strlen(VIR_NET_GENERATED_VNET_PREFIX);
 
         if (virStrToLong_ui(idstr, NULL, 10, &id) >= 0) {
             virMutexLock(&virNetDevTapCreateMutex);
@@ -200,7 +200,7 @@ static int
 virNetDevTapGenerateName(char **ifname)
 {
     int id;
-    double maxIDd = pow(10, IFNAMSIZ - 1 - strlen(VIR_NET_GENERATED_TAP_PREFIX));
+    double maxIDd = pow(10, IFNAMSIZ - 1 - strlen(VIR_NET_GENERATED_VNET_PREFIX));
     int maxID = INT_MAX;
     int attempts = 0;
 
@@ -227,7 +227,7 @@ virNetDevTapGenerateName(char **ifname)
 
     virReportError(VIR_ERR_INTERNAL_ERROR,
                    _("no unused %s names available"),
-                   VIR_NET_GENERATED_TAP_PREFIX);
+                   VIR_NET_GENERATED_VNET_PREFIX);
     return -1;
 }
 
@@ -270,7 +270,7 @@ int virNetDevTapCreate(char **ifname,
      * immediately re-using names that have just been released, which
      * can lead to race conditions).
      */
-    if (STREQ(*ifname, VIR_NET_GENERATED_TAP_PREFIX "%d") &&
+    if (STREQ(*ifname, VIR_NET_GENERATED_VNET_PREFIX "%d") &&
         virNetDevTapGenerateName(ifname) < 0) {
         goto cleanup;
     }