[libvirt] [PATCH rebase v4 3/5] qemu: introduce qemuARPGetInterfaces to get IP from host's arp table

[Michal Privoznik]

On 03/08/2018 08:11 AM, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao at gmail.com>
> 
> introduce VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP to get ip address
> of VM from the message of netlink RTM_GETNEIGH
> 
> Signed-off-by: Chen Hanxiao <chenhanxiao at gmail.com>
> ---
> v4：
>   remove dummy entry
>   use VIR_APPEND_ELEMENT
> 
> v3:
>   add docs in virDomainInterfaceAddresses
>   remove error label
>   show network interface which did not match the arp table
> 
>  include/libvirt/libvirt-domain.h |  1 +
>  src/libvirt-domain.c             |  7 ++++
>  src/qemu/qemu_driver.c           | 72 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 80 insertions(+)
> 
> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
> index 4048acf38..38e2d9a3e 100644
> --- a/include/libvirt/libvirt-domain.h
> +++ b/include/libvirt/libvirt-domain.h
> @@ -4665,6 +4665,7 @@ typedef virMemoryParameter *virMemoryParameterPtr;
>  typedef enum {
>      VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_LEASE = 0, /* Parse DHCP lease file */
>      VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_AGENT = 1, /* Query qemu guest agent */
> +    VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP = 2, /* Query ARP tables */
>  
>  # ifdef VIR_ENUM_SENTINELS
>      VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_LAST
> diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> index eaec0979a..1ae83610d 100644
> --- a/src/libvirt-domain.c
> +++ b/src/libvirt-domain.c
> @@ -11721,6 +11721,13 @@ virDomainFSInfoFree(virDomainFSInfoPtr info)
>   * To match such interface with the one from @dom XML use MAC address or IP
>   * range.
>   *
> + * If @source is VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP, the /proc/net/arp
> + * will be check to obtain the interface addresses.

This should rather say 'arp table' because we are not obtaining the arp
table through /proc file anymore.

> + * As the arp cache did not refresh in time, the returned ip address
> + * may be unreachable.
> + * As the route config of the guest, the returned mac address
> + * may be duplicated.
> + *
>   * @ifaces->name and @ifaces->hwaddr are never NULL.
>   *
>   * The caller *must* free @ifaces when no longer needed. Usual use case
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 9e715e7a0..7d77e1643 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -70,6 +70,7 @@
>  #include "virnetdevopenvswitch.h"
>  #include "capabilities.h"
>  #include "viralloc.h"
> +#include "virarptable.h"
>  #include "viruuid.h"
>  #include "domain_conf.h"
>  #include "domain_audit.h"
> @@ -157,6 +158,9 @@ static int qemuGetDHCPInterfaces(virDomainPtr dom,
>                                   virDomainObjPtr vm,
>                                   virDomainInterfacePtr **ifaces);
>  
> +static int qemuARPGetInterfaces(virDomainObjPtr vm,
> +                                virDomainInterfacePtr **ifaces);
> +
>  static virQEMUDriverPtr qemu_driver;
>  
>  
> @@ -20516,6 +20520,10 @@ qemuDomainInterfaceAddresses(virDomainPtr dom,
>  
>          break;
>  
> +    case VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP:
> +        ret = qemuARPGetInterfaces(vm, ifaces);
> +        break;
> +
>      default:
>          virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED,
>                         _("Unknown IP address data source %d"),
> @@ -20625,6 +20633,70 @@ qemuGetDHCPInterfaces(virDomainPtr dom,
>  }
>  
>  
> +static int
> +qemuARPGetInterfaces(virDomainObjPtr vm,
> +                     virDomainInterfacePtr **ifaces)
> +{
> +    size_t i, j;
> +    size_t ifaces_count = 0;
> +    int ret = -1;
> +    char macaddr[VIR_MAC_STRING_BUFLEN];
> +    virDomainInterfacePtr *ifaces_ret = NULL;
> +    virDomainInterfacePtr iface = NULL;
> +    virArpTablePtr table;
> +
> +    table = virArpTableGet();
> +    if (!table)
> +        goto cleanup;
> +
> +    for (i = 0; i < vm->def->nnets; i++) {
> +        if (vm->def->nets[i]->type != VIR_DOMAIN_NET_TYPE_NETWORK)
> +            continue;
> +
> +        virMacAddrFormat(&(vm->def->nets[i]->mac), macaddr);
> +        virArpTableEntry entry;


When declaring variables in a block the same rules apply as when doing
so at top level. That is, this @entry declaration should be the first
line in this block. Alternatively, it can be declared in the next for loop.

> +        for (j = 0; j < table->n; j++) {
> +            entry = table->t[j];
> +            if (STREQ(entry.mac, macaddr)) {
> +                if (VIR_ALLOC(iface) < 0)
> +                    goto cleanup;
> +
> +                iface->naddrs = 1;
> +                if (VIR_STRDUP(iface->name, vm->def->nets[i]->ifname) < 0)
> +                    goto cleanup;
> +
> +                if (VIR_STRDUP(iface->hwaddr, macaddr) < 0)
> +                    goto cleanup;
> +
> +                if (VIR_ALLOC_N(iface->addrs, iface->naddrs) < 0)
> +                    goto cleanup;
> +
> +                if (VIR_STRDUP(iface->addrs->addr, entry.ipaddr) < 0)
> +                    goto cleanup;
> +
> +                if (VIR_APPEND_ELEMENT(ifaces_ret, ifaces_count, iface) < 0)
> +                    goto cleanup;
> +
> +            }
> +        }
> +    }
> +
> +    VIR_STEAL_PTR(*ifaces, ifaces_ret);
> +    ret = ifaces_count;
> +
> + cleanup:
> +    virArpTableFree(table);
> +
> +    if (ifaces_ret) {
> +        for (i = 0; i < ifaces_count; i++)
> +            virDomainInterfaceFree(ifaces_ret[i]);
> +    }
> +    VIR_FREE(ifaces_ret);
> +
> +    return ret;
> +}
> +
> +
>  static int
>  qemuDomainSetUserPassword(virDomainPtr dom,
>                            const char *user,
> 

Michal