migration/tls: extract migration_tls_client_create for common-use

migration_tls_client_create will be used in multifd-tls, let's
extract it.

Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Signed-off-by: Yan Jin <jinyan12@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <1600139042-104593-3-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/tls.c

@@ -22,7 +22,6 @@
 #include "channel.h"
 #include "migration.h"
 #include "tls.h"
-#include "io/channel-tls.h"
 #include "crypto/tlscreds.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
@@ -125,11 +124,10 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
     object_unref(OBJECT(ioc));
 }
 
-
-void migration_tls_channel_connect(MigrationState *s,
-                                   QIOChannel *ioc,
-                                   const char *hostname,
-                                   Error **errp)
+QIOChannelTLS *migration_tls_client_create(MigrationState *s,
+                                           QIOChannel *ioc,
+                                           const char *hostname,
+                                           Error **errp)
 {
     QCryptoTLSCreds *creds;
     QIOChannelTLS *tioc;
@@ -137,7 +135,7 @@ void migration_tls_channel_connect(MigrationState *s,
     creds = migration_tls_get_creds(
         s, QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT, errp);
     if (!creds) {
-        return;
+        return NULL;
     }
 
     if (s->parameters.tls_hostname && *s->parameters.tls_hostname) {
@@ -145,11 +143,23 @@ void migration_tls_channel_connect(MigrationState *s,
     }
     if (!hostname) {
         error_setg(errp, "No hostname available for TLS");
-        return;
+        return NULL;
     }
 
     tioc = qio_channel_tls_new_client(
         ioc, creds, hostname, errp);
+
+    return tioc;
+}
+
+void migration_tls_channel_connect(MigrationState *s,
+                                   QIOChannel *ioc,
+                                   const char *hostname,
+                                   Error **errp)
+{
+    QIOChannelTLS *tioc;
+
+    tioc = migration_tls_client_create(s, ioc, hostname, errp);
     if (!tioc) {
         return;
     }

migration/tls.h

@@ -22,11 +22,17 @@
 #define QEMU_MIGRATION_TLS_H
 
 #include "io/channel.h"
+#include "io/channel-tls.h"
 
 void migration_tls_channel_process_incoming(MigrationState *s,
                                             QIOChannel *ioc,
                                             Error **errp);
 
+QIOChannelTLS *migration_tls_client_create(MigrationState *s,
+                                           QIOChannel *ioc,
+                                           const char *hostname,
+                                           Error **errp);
+
 void migration_tls_channel_connect(MigrationState *s,
                                    QIOChannel *ioc,
                                    const char *hostname,