[libvirt] [PATCH 2/3] qemu: Implement support for VIR_MIGRATE_PARAM_LISTEN_ADDRESS

[Daniel P. Berrange]

On Wed, Oct 09, 2013 at 01:02:14PM +0200, Michal Privoznik wrote:
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/qemu/qemu_driver.c    | 26 +++++++++----
>  src/qemu/qemu_migration.c | 98 +++++++++++++++++++++++++++++++++--------------
>  src/qemu/qemu_migration.h | 13 ++++---
>  3 files changed, 96 insertions(+), 41 deletions(-)
> @@ -2260,31 +2260,61 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
>          if (VIR_STRDUP(migrateFrom, "stdio") < 0)
>              goto cleanup;
>      } else {
> +        virSocketAddr listenAddressSocket;
> +        bool hostIPv6Capable = false;
> +        bool qemuIPv6Capable = false;
>          virQEMUCapsPtr qemuCaps = NULL;
>          struct addrinfo *info = NULL;
>          struct addrinfo hints = { .ai_flags = AI_ADDRCONFIG,
> -                                  .ai_socktype = SOCK_STREAM };
> +            .ai_socktype = SOCK_STREAM };
>  
> +        if (getaddrinfo("::", NULL, &hints, &info) == 0) {
> +            freeaddrinfo(info);
> +            hostIPv6Capable = true;
> +        }
>          if (!(qemuCaps = virQEMUCapsCacheLookupCopy(driver->qemuCapsCache,
>                                                      (*def)->emulator)))
>              goto cleanup;
>  
> -        /* Listen on :: instead of 0.0.0.0 if QEMU understands it
> -         * and there is at least one IPv6 address configured
> -         */
> -        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_IPV6_MIGRATION) &&
> -            getaddrinfo("::", NULL, &hints, &info) == 0) {
> -            freeaddrinfo(info);
> -            listenAddr = "[::]";
> +        qemuIPv6Capable = virQEMUCapsGet(qemuCaps, QEMU_CAPS_IPV6_MIGRATION);
> +        virObjectUnref(qemuCaps);
> +
> +        if (listenAddress &&
> +            virSocketAddrParse(&listenAddressSocket, listenAddress, AF_UNSPEC) > 0) {
> +            /* address parsed successfully */
> +
> +            if (virSocketAddrIsWildcard(&listenAddressSocket)) {
> +                /* user wants us to listen on 0.0.0.0 or :: */
> +
> +                if (VIR_SOCKET_ADDR_IS_FAMILY(&listenAddressSocket, AF_INET6)) {
> +                    if (!qemuIPv6Capable) {
> +                        virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
> +                                       _("qemu isn't capable of IPv6"));
> +                        goto cleanup;
> +                    }
> +                    if (!hostIPv6Capable) {
> +                        virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
> +                                       _("host isn't capable of IPv6"));
> +                        goto cleanup;
> +                    }
> +                    listenAddress = "[::]";
> +                }
> +            }
>          } else {
> -            listenAddr = "0.0.0.0";
> +            /* Don't error out, the @listenAddress may be a hostname */
> +            if (!listenAddress) {
> +                /* Listen on :: instead of 0.0.0.0 if QEMU understands it
> +                 * and there is at least one IPv6 address configured
> +                 */
> +                listenAddress = qemuIPv6Capable && hostIPv6Capable ?
> +                    "[::]" : "0.0.0.0";
> +            }
>          }

I think this if/else would be clearer as

   if (listenAddress) {
      if (virSocketAddrParse(&listenAddressSocket, listenAddress, AF_UNSPEC) < 0) {
         virResetLastError();
         ...
      } else {
         ....
      }
   } else {
      listenAddress = qemuIPv6Capable && hostIPv6Capable ?
         "[::]" : "0.0.0.0";
   }


Though this still means we'll be polluting the logs with the errors if this is
a hostname. So perhaps we need a method  virSocketAddrIsNumeric(const char *addR)
so we can skip the parse stage entirely without errors, if it is a hostname.

Daniel
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