migration: use "" as the default for tls-creds/hostname

The tls-creds parameter has a default value of NULL indicating
that TLS should not be used. Setting it to non-NULL enables
use of TLS. Once tls-creds are set to a non-NULL value via the
monitor, it isn't possible to set them back to NULL again, due
to current implementation limitations. The empty string is not
a valid QObject identifier, so this switches to use "" as the
default, indicating that TLS will not be used

The tls-hostname parameter has a default value of NULL indicating
the the hostname from the migrate connection URI should be used.
Again, once tls-hostname is set non-NULL, to override the default
hostname for x509 cert validation, it isn't possible to reset it
back to NULL via the monitor. The empty string is not a valid
hostname, so this switches to use "" as the default, indicating
that the migrate URI hostname should be used.

Using "" as the default for both, also means that the monitor
commands "info migrate_parameters" / "query-migrate-parameters"
will report existance of tls-creds/tls-parameters even when set
to their default values.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/migration/migration.c b/migration/migration.c
index 3dab6845b11f57643db1a20c6ceb75fac1220a55..54060f749a95bfcfee9dc5e0d2994dae295d8579 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -110,6 +110,8 @@ MigrationState *migrate_get_current(void)
 
     if (!once) {
         qemu_mutex_init(&current_migration.src_page_req_mutex);
+        current_migration.parameters.tls_creds = g_strdup("");
+        current_migration.parameters.tls_hostname = g_strdup("");
         once = true;
     }
     return &current_migration;
@@ -458,6 +460,7 @@ void migration_channel_process_incoming(MigrationState *s,
         ioc, object_get_typename(OBJECT(ioc)));
 
     if (s->parameters.tls_creds &&
+        *s->parameters.tls_creds &&
         !object_dynamic_cast(OBJECT(ioc),
                              TYPE_QIO_CHANNEL_TLS)) {
         Error *local_err = NULL;
@@ -480,6 +483,7 @@ void migration_channel_connect(MigrationState *s,
         ioc, object_get_typename(OBJECT(ioc)), hostname);
 
     if (s->parameters.tls_creds &&
+        *s->parameters.tls_creds &&
         !object_dynamic_cast(OBJECT(ioc),
                              TYPE_QIO_CHANNEL_TLS)) {
         Error *local_err = NULL;

diff --git a/migration/tls.c b/migration/tls.c
index 203c11d025de8f4c0fadb8eb924b2ab9971ffefe..45bec44ca4fac5eefbe875f1b15d8971045a47c4 100644 (file)
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -141,7 +141,7 @@ void migration_tls_channel_connect(MigrationState *s,
         return;
     }
 
-    if (s->parameters.tls_hostname) {
+    if (s->parameters.tls_hostname && *s->parameters.tls_hostname) {
         hostname = s->parameters.tls_hostname;
     }
     if (!hostname) {

diff --git a/qapi-schema.json b/qapi-schema.json
index 32b4a4b782744ae1b5c63a8d86a516b96fa65bb7..eb9bf67bd9750bdfac28f3f23eeda7dd28a2c83b 100644 (file)
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1036,6 +1036,8 @@
 #             credentials must be for a 'server' endpoint. Setting this
 #             will enable TLS for all migrations. The default is unset,
 #             resulting in unsecured migration at the QEMU level. (Since 2.7)
+#             An empty string means that QEMU will use plain text mode for
+#             migration, rather than TLS (Since 2.9)
 #
 # @tls-hostname: #optional hostname of the target host for the migration. This
 #                is required when using x509 based TLS credentials and the
@@ -1043,6 +1045,8 @@
 #                example if using fd: or exec: based migration, the
 #                hostname must be provided so that the server's x509
 #                certificate identity can be validated. (Since 2.7)
+#                An empty string means that QEMU will use the hostname
+#                associated with the migration URI, if any. (Since 2.9)
 #
 # @max-bandwidth: to set maximum speed for migration. maximum speed in
 #                 bytes per second. (Since 2.8)