From: Michal Privoznik <[email protected]>

The virDomainInterfaceAddresses() API returns an array of
_virDomainInterface structs which then describe IP addresses
associated with given domain. The struct contains 'name' member
which is documented deliberately vaguely: "interface name". This
is because depending on the source of truth used (controlled by
'source' argument) the name can be wildly different from the one
in domain XML. Now, in case of source =
VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP, the host's ARP table is
parsed and matching interfaces are found by comparing MAC
addresses. If it's a match then the 'name' is set to net->ifname
(corresponds to /interface/target/@dev). But that is not always
set and sometimes may be NULL (e.g. for hostdevs, usernet). We
can't change the API (like we did for hwaddr in v1.2.14-rc1~105)
because this is already released. So the next best thing to do is
to put the interface alias in there.

To be on a safe side, do the same change to the
VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_LEASE case.

Resolves: https://issues.redhat.com/browse/RHEL-141496
Signed-off-by: Michal Privoznik <[email protected]>
---
 src/conf/domain_conf.c | 16 ++++++++++++++--
 src/libvirt-domain.c   |  2 ++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index d00a43e969..8b26de674e 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -15598,6 +15598,12 @@ virDomainNetDHCPInterfaces(virDomainDef *def,
             goto error;
 
         if (n_leases) {
+            const char *ifname = def->nets[i]->ifname;
+
+            if (!ifname) {
+                ifname = def->nets[i]->info.alias;
+            }
+
             ifaces_ret = g_renew(virDomainInterfacePtr, ifaces_ret, 
ifaces_count + 1);
             ifaces_ret[ifaces_count] = g_new0(virDomainInterface, 1);
             iface = ifaces_ret[ifaces_count];
@@ -15606,7 +15612,7 @@ virDomainNetDHCPInterfaces(virDomainDef *def,
             /* Assuming each lease corresponds to a separate IP */
             iface->naddrs = n_leases;
             iface->addrs = g_new0(virDomainIPAddress, iface->naddrs);
-            iface->name = g_strdup(def->nets[i]->ifname);
+            iface->name = g_strdup(ifname);
             iface->hwaddr = g_strdup(macaddr);
         }
 
@@ -15660,9 +15666,15 @@ virDomainNetARPInterfaces(virDomainDef *def,
             virArpTableEntry entry = table->t[j];
 
             if (STREQ(entry.mac, macaddr)) {
+                const char *ifname = def->nets[i]->ifname;
+
+                if (!ifname) {
+                    ifname = def->nets[i]->info.alias;
+                }
+
                 iface = g_new0(virDomainInterface, 1);
 
-                iface->name = g_strdup(def->nets[i]->ifname);
+                iface->name = g_strdup(ifname);
 
                 iface->hwaddr = g_strdup(macaddr);
 
diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index a278c4679d..a1f6efde20 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -12880,6 +12880,8 @@ virDomainFSInfoFree(virDomainFSInfoPtr info)
  * Note that for some @source values some pieces of returned @ifaces
  * might be unset (e.g. VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP does not
  * set IP address prefix as ARP table does not have any notion of that).
+ * Moreover, it may happen that the interface doesn't have a name. In
+ * that case, @ifaces->name is set to the interface's device alias.
  *
  * @ifaces->name is never NULL, and @ifaces->hwaddr may be NULL.
  *
-- 
2.52.0

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