Merge remote-tracking branch 'remotes/berrange/tags/pull-qio-2017-01-23-2' into staging

Merge io/ 2017-01-23

# gpg: Signature made Mon 23 Jan 2017 15:56:14 GMT
# gpg:                using RSA key 0xBE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>"
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>"
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange/tags/pull-qio-2017-01-23-2:
  io: introduce a DNS resolver API
  io: remove Error parameter from QIOTask thread worker
  io: change the QIOTask callback signature
  io: add ability to associate an error with a task
  io: add ability to associate an opaque "result" with with a task
  io: fix typo in docs for QIOTask
  io: stop incrementing reference in qio_task_get_source
  sockets: add ability to disable DNS resolution for InetSocketAddress

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

22 files changed, 760 insertions, 169 deletions

diff --git a/include/io/dns-resolver.h b/include/io/dns-resolver.h
new file mode 100644
index 0000000000..2f69c08c13
--- /dev/null
+++ b/include/io/dns-resolver.h
@@ -0,0 +1,228 @@
+/*
+ * QEMU DNS resolver
+ *
+ * Copyright (c) 2016-2017 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QIO_DNS_RESOLVER_H
+#define QIO_DNS_RESOLVER_H
+
+#include "qemu-common.h"
+#include "qom/object.h"
+#include "io/task.h"
+
+#define TYPE_QIO_DNS_RESOLVER "qio-dns-resolver"
+#define QIO_DNS_RESOLVER(obj)                                    \
+    OBJECT_CHECK(QIODNSResolver, (obj), TYPE_QIO_DNS_RESOLVER)
+#define QIO_DNS_RESOLVER_CLASS(klass)                                    \
+    OBJECT_CLASS_CHECK(QIODNSResolverClass, klass, TYPE_QIO_DNS_RESOLVER)
+#define QIO_DNS_RESOLVER_GET_CLASS(obj)                                  \
+    OBJECT_GET_CLASS(QIODNSResolverClass, obj, TYPE_QIO_DNS_RESOLVER)
+
+typedef struct QIODNSResolver QIODNSResolver;
+typedef struct QIODNSResolverClass QIODNSResolverClass;
+
+/**
+ * QIODNSResolver:
+ *
+ * The QIODNSResolver class provides a framework for doing
+ * DNS resolution on SocketAddress objects, independently
+ * of socket creation.
+ *
+ * <example>
+ *   <title>Resolving addresses synchronously</title>
+ *   <programlisting>
+ *    int mylisten(SocketAddress *addr, Error **errp) {
+ *      QIODNSResolver *resolver = qio_dns_resolver_get_instance();
+ *      SocketAddress **rawaddrs = NULL;
+ *      size_t nrawaddrs = 0;
+ *      Error *err = NULL;
+ *      QIOChannel **socks = NULL;
+ *      size_t nsocks = 0;
+ *
+ *      if (qio_dns_resolver_lookup_sync(dns, addr, &nrawaddrs,
+ *                                       &rawaddrs, errp) < 0) {
+ *          return -1;
+ *      }
+ *
+ *      for (i = 0; i < nrawaddrs; i++) {
+ *         QIOChannel *sock = qio_channel_new();
+ *         Error *local_err = NULL;
+ *         qio_channel_listen_sync(sock, rawaddrs[i], &local_err);
+ *         if (local_err) {
+ *            error_propagate(&err, local_err);
+ *         } else {
+ *            socks = g_renew(QIOChannelSocket *, socks, nsocks + 1);
+ *            socks[nsocks++] = sock;
+ *         }
+ *         qapi_free_SocketAddress(rawaddrs[i]);
+ *      }
+ *      g_free(rawaddrs);
+ *
+ *      if (nsocks == 0) {
+ *         error_propagate(errp, err);
+ *      } else {
+ *         error_free(err);
+ *      }
+ *   }
+ *   </programlisting>
+ * </example>
+ *
+ * <example>
+ *   <title>Resolving addresses asynchronously</title>
+ *   <programlisting>
+ *    typedef struct MyListenData {
+ *       Error *err;
+ *       QIOChannelSocket **socks;
+ *       size_t nsocks;
+ *    } MyListenData;
+ *
+ *    void mylistenresult(QIOTask *task, void *opaque) {
+ *      MyListenData *data = opaque;
+ *      QIODNSResolver *resolver =
+ *         QIO_DNS_RESOLVER(qio_task_get_source(task);
+ *      SocketAddress **rawaddrs = NULL;
+ *      size_t nrawaddrs = 0;
+ *      Error *err = NULL;
+ *
+ *      if (qio_task_propagate_error(task, &data->err)) {
+ *         return;
+ *      }
+ *
+ *      qio_dns_resolver_lookup_result(resolver, task,
+ *                                     &nrawaddrs, &rawaddrs);
+ *
+ *      for (i = 0; i < nrawaddrs; i++) {
+ *         QIOChannel *sock = qio_channel_new();
+ *         Error *local_err = NULL;
+ *         qio_channel_listen_sync(sock, rawaddrs[i], &local_err);
+ *         if (local_err) {
+ *            error_propagate(&err, local_err);
+ *         } else {
+ *            socks = g_renew(QIOChannelSocket *, socks, nsocks + 1);
+ *            socks[nsocks++] = sock;
+ *         }
+ *         qapi_free_SocketAddress(rawaddrs[i]);
+ *      }
+ *      g_free(rawaddrs);
+ *
+ *      if (nsocks == 0) {
+ *         error_propagate(&data->err, err);
+ *      } else {
+ *         error_free(err);
+ *      }
+ *    }
+ *
+ *    void mylisten(SocketAddress *addr, MyListenData *data) {
+ *      QIODNSResolver *resolver = qio_dns_resolver_get_instance();
+ *      qio_dns_resolver_lookup_async(dns, addr,
+ *                                    mylistenresult, data, NULL);
+ *    }
+ *   </programlisting>
+ * </example>
+ */
+struct QIODNSResolver {
+    Object parent;
+};
+
+struct QIODNSResolverClass {
+    ObjectClass parent;
+};
+
+
+/**
+ * qio_dns_resolver_get_instance:
+ *
+ * Get the singleton dns resolver instance. The caller
+ * does not own a reference on the returned object.
+ *
+ * Returns: the single dns resolver instance
+ */
+QIODNSResolver *qio_dns_resolver_get_instance(void);
+
+/**
+ * qio_dns_resolver_lookup_sync:
+ * @resolver: the DNS resolver instance
+ * @addr: the address to resolve
+ * @naddr: pointer to hold number of resolved addresses
+ * @addrs: pointer to hold resolved addresses
+ * @errp: pointer to NULL initialized error object
+ *
+ * This will attempt to resolve the address provided
+ * in @addr. If resolution succeeds, @addrs will be filled
+ * with all the resolved addresses. @naddrs will specify
+ * the number of entries allocated in @addrs. The caller
+ * is responsible for freeing each entry in @addrs, as
+ * well as @addrs itself. @naddrs is guaranteed to be
+ * greater than zero on success.
+ *
+ * DNS resolution will be done synchronously so execution
+ * of the caller may be blocked for an arbitrary length
+ * of time.
+ *
+ * Returns: 0 if resolution was successful, -1 on error
+ */
+int qio_dns_resolver_lookup_sync(QIODNSResolver *resolver,
+                                 SocketAddress *addr,
+                                 size_t *naddrs,
+                                 SocketAddress ***addrs,
+                                 Error **errp);
+
+/**
+ * qio_dns_resolver_lookup_async:
+ * @resolver: the DNS resolver instance
+ * @addr: the address to resolve
+ * @func: the callback to invoke on lookup completion
+ * @opaque: data blob to pass to @func
+ * @notify: the callback to free @opaque, or NULL
+ *
+ * This will attempt to resolve the address provided
+ * in @addr. The callback @func will be invoked when
+ * resolution has either completed or failed. On
+ * success, the @func should call the method
+ * qio_dns_resolver_lookup_result() to obtain the
+ * results.
+ *
+ * DNS resolution will be done asynchronously so execution
+ * of the caller will not be blocked.
+ */
+void qio_dns_resolver_lookup_async(QIODNSResolver *resolver,
+                                   SocketAddress *addr,
+                                   QIOTaskFunc func,
+                                   gpointer opaque,
+                                   GDestroyNotify notify);
+
+/**
+ * qio_dns_resolver_lookup_result:
+ * @resolver: the DNS resolver instance
+ * @task: the task object to get results for
+ * @naddr: pointer to hold number of resolved addresses
+ * @addrs: pointer to hold resolved addresses
+ *
+ * This method should be called from the callback passed
+ * to qio_dns_resolver_lookup_async() in order to obtain
+ * results.  @addrs will be filled with all the resolved
+ * addresses. @naddrs will specify the number of entries
+ * allocated in @addrs. The caller is responsible for
+ * freeing each entry in @addrs, as well as @addrs itself.
+ */
+void qio_dns_resolver_lookup_result(QIODNSResolver *resolver,
+                                    QIOTask *task,
+                                    size_t *naddrs,
+                                    SocketAddress ***addrs);
+
+#endif /* QIO_DNS_RESOLVER_H */
diff --git a/include/io/task.h b/include/io/task.h
index 42028cb424..6021f51336 100644
--- a/include/io/task.h
+++ b/include/io/task.h
@@ -26,13 +26,11 @@
 
 typedef struct QIOTask QIOTask;
 
-typedef void (*QIOTaskFunc)(Object *source,
-                            Error *err,
+typedef void (*QIOTaskFunc)(QIOTask *task,
                             gpointer opaque);
 
-typedef int (*QIOTaskWorker)(QIOTask *task,
-                             Error **errp,
-                             gpointer opaque);
+typedef void (*QIOTaskWorker)(QIOTask *task,
+                              gpointer opaque);
 
 /**
  * QIOTask:
@@ -44,12 +42,12 @@ typedef int (*QIOTaskWorker)(QIOTask *task,
  * a public API which accepts a task callback:
  *
  * <example>
- *   <title>Task callback function signature</title>
+ *   <title>Task function signature</title>
  *   <programlisting>
  *  void myobject_operation(QMyObject *obj,
  *                          QIOTaskFunc *func,
  *                          gpointer opaque,
- *                          GDestroyNotify *notify);
+ *                          GDestroyNotify notify);
  *   </programlisting>
  * </example>
  *
@@ -57,17 +55,41 @@ typedef int (*QIOTaskWorker)(QIOTask *task,
  * is data to pass to it. The optional 'notify' function is used
  * to free 'opaque' when no longer needed.
  *
- * Now, lets say the implementation of this method wants to set
- * a timer to run once a second checking for completion of some
- * activity. It would do something like
+ * When the operation completes, the 'func' callback will be
+ * invoked, allowing the calling code to determine the result
+ * of the operation. An example QIOTaskFunc implementation may
+ * look like
  *
  * <example>
- *   <title>Task callback function implementation</title>
+ *   <title>Task callback implementation</title>
+ *   <programlisting>
+ *  static void myobject_operation_notify(QIOTask *task,
+ *                                        gpointer opaque)
+ *  {
+ *      Error *err = NULL;
+ *      if (qio_task_propagate_error(task, &err)) {
+ *          ...deal with the failure...
+ *          error_free(err);
+ *      } else {
+ *          QMyObject *src = QMY_OBJECT(qio_task_get_source(task));
+ *          ...deal with the completion...
+ *      }
+ *  }
+ *   </programlisting>
+ * </example>
+ *
+ * Now, lets say the implementation of the method using the
+ * task wants to set a timer to run once a second checking
+ * for completion of some activity. It would do something
+ * like
+ *
+ * <example>
+ *   <title>Task function implementation</title>
  *   <programlisting>
  *    void myobject_operation(QMyObject *obj,
  *                            QIOTaskFunc *func,
  *                            gpointer opaque,
- *                            GDestroyNotify *notify)
+ *                            GDestroyNotify notify)
  *    {
  *      QIOTask *task;
  *
@@ -102,8 +124,8 @@ typedef int (*QIOTaskWorker)(QIOTask *task,
  *
  *      ...check something important...
  *       if (err) {
- *           qio_task_abort(task, err);
- *           error_free(task);
+ *           qio_task_set_error(task, err);
+ *           qio_task_complete(task);
  *           return FALSE;
  *       } else if (...work is completed ...) {
  *           qio_task_complete(task);
@@ -115,6 +137,10 @@ typedef int (*QIOTaskWorker)(QIOTask *task,
  *   </programlisting>
  * </example>
  *
+ * The 'qio_task_complete' call in this method will trigger
+ * the callback func 'myobject_operation_notify' shown
+ * earlier to deal with the results.
+ *
  * Once this function returns false, object_unref will be called
  * automatically on the task causing it to be released and the
  * ref on QMyObject dropped too.
@@ -136,25 +162,23 @@ typedef int (*QIOTaskWorker)(QIOTask *task,
  * socket listen using QIOTask would require:
  *
  * <example>
- *    static int myobject_listen_worker(QIOTask *task,
- *                                      Error **errp,
- *                                      gpointer opaque)
+ *    static void myobject_listen_worker(QIOTask *task,
+ *                                       gpointer opaque)
  *    {
  *       QMyObject obj = QMY_OBJECT(qio_task_get_source(task));
  *       SocketAddress *addr = opaque;
+ *       Error *err = NULL;
  *
- *       obj->fd = socket_listen(addr, errp);
- *       if (obj->fd < 0) {
- *          return -1;
- *       }
- *       return 0;
+ *       obj->fd = socket_listen(addr, &err);
+ *
+         qio_task_set_error(task, err);
  *    }
  *
  *    void myobject_listen_async(QMyObject *obj,
  *                               SocketAddress *addr,
  *                               QIOTaskFunc *func,
  *                               gpointer opaque,
- *                               GDestroyNotify *notify)
+ *                               GDestroyNotify notify)
  *    {
  *      QIOTask *task;
  *      SocketAddress *addrCopy;
@@ -187,8 +211,8 @@ typedef int (*QIOTaskWorker)(QIOTask *task,
  * 'err' attribute in the task object to determine if
  * the operation was successful or not.
  *
- * The returned task will be released when one of
- * qio_task_abort() or qio_task_complete() are invoked.
+ * The returned task will be released when qio_task_complete()
+ * is invoked.
  *
  * Returns: the task struct
  */
@@ -204,10 +228,8 @@ QIOTask *qio_task_new(Object *source,
  * @opaque: opaque data to pass to @worker
  * @destroy: function to free @opaque
  *
- * Run a task in a background thread. If @worker
- * returns 0 it will call qio_task_complete() in
- * the main event thread context. If @worker
- * returns -1 it will call qio_task_abort() in
+ * Run a task in a background thread. When @worker
+ * returns it will call qio_task_complete() in
  * the main event thread context.
  */
 void qio_task_run_in_thread(QIOTask *task,
@@ -219,24 +241,69 @@ void qio_task_run_in_thread(QIOTask *task,
  * qio_task_complete:
  * @task: the task struct
  *
- * Mark the operation as successfully completed
- * and free the memory for @task.
+ * Invoke the completion callback for @task and
+ * then free its memory.
  */
 void qio_task_complete(QIOTask *task);
 
+
+/**
+ * qio_task_set_error:
+ * @task: the task struct
+ * @err: pointer to the error, or NULL
+ *
+ * Associate an error with the task, which can later
+ * be retrieved with the qio_task_propagate_error()
+ * method. This method takes ownership of @err, so
+ * it is not valid to access it after this call
+ * completes. If @err is NULL this is a no-op. If
+ * this is call multiple times, only the first
+ * provided @err will be recorded, later ones will
+ * be discarded and freed.
+ */
+void qio_task_set_error(QIOTask *task,
+                        Error *err);
+
+
 /**
- * qio_task_abort:
+ * qio_task_propagate_error:
  * @task: the task struct
- * @err: the error to record for the operation
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Propagate the error associated with @task
+ * into @errp.
+ *
+ * Returns: true if an error was propagated, false otherwise
+ */
+bool qio_task_propagate_error(QIOTask *task,
+                              Error **errp);
+
+
+/**
+ * qio_task_set_result_pointer:
+ * @task: the task struct
+ * @result: pointer to the result data
+ *
+ * Associate an opaque result with the task,
+ * which can later be retrieved with the
+ * qio_task_get_result_pointer() method
+ *
+ */
+void qio_task_set_result_pointer(QIOTask *task,
+                                 gpointer result,
+                                 GDestroyNotify notify);
+
+
+/**
+ * qio_task_get_result_pointer:
+ * @task: the task struct
+ *
+ * Retrieve the opaque result data associated
+ * with the task, if any.
  *
- * Mark the operation as failed, with @err providing
- * details about the failure. The @err may be freed
- * afer the function returns, as the notification
- * callback is invoked synchronously. The @task will
- * be freed when this call completes.
+ * Returns: the task result, or NULL
  */
-void qio_task_abort(QIOTask *task,
-                    Error *err);
+gpointer qio_task_get_result_pointer(QIOTask *task);
 
 
 /**
@@ -244,9 +311,10 @@ void qio_task_abort(QIOTask *task,
  * @task: the task struct
  *
  * Get the source object associated with the background
- * task. This returns a new reference to the object,
- * which the caller must released with object_unref()
- * when no longer required.
+ * task. The caller does not own a reference on the
+ * returned Object, and so should call object_ref()
+ * if it wants to keep the object pointer outside the
+ * lifetime of the QIOTask object.
  *
  * Returns: the source object
  */
diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
index 5589e6842b..5f1bab9b3e 100644
--- a/include/qemu/sockets.h
+++ b/include/qemu/sockets.h
@@ -32,6 +32,8 @@ int socket_set_fast_reuse(int fd);
  */
 typedef void NonBlockingConnectHandler(int fd, Error *err, void *opaque);
 
+int inet_ai_family_from_address(InetSocketAddress *addr,
+                                Error **errp);
 InetSocketAddress *inet_parse(const char *str, Error **errp);
 int inet_connect(const char *str, Error **errp);
 int inet_connect_saddr(InetSocketAddress *saddr, Error **errp,
diff --git a/io/Makefile.objs b/io/Makefile.objs
index 9d8337d89a..12983cca79 100644
--- a/io/Makefile.objs
+++ b/io/Makefile.objs
@@ -7,4 +7,5 @@ io-obj-y += channel-tls.o
 io-obj-y += channel-watch.o
 io-obj-y += channel-websock.o
 io-obj-y += channel-util.o
+io-obj-y += dns-resolver.o
 io-obj-y += task.o
diff --git a/io/channel-socket.c b/io/channel-socket.c
index d7e03f6266..f385233f18 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -156,20 +156,16 @@ int qio_channel_socket_connect_sync(QIOChannelSocket *ioc,
 }
 
 
-static int qio_channel_socket_connect_worker(QIOTask *task,
-                                             Error **errp,
-                                             gpointer opaque)
+static void qio_channel_socket_connect_worker(QIOTask *task,
+                                              gpointer opaque)
 {
     QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
     SocketAddress *addr = opaque;
-    int ret;
+    Error *err = NULL;
 
-    ret = qio_channel_socket_connect_sync(ioc,
-                                          addr,
-                                          errp);
+    qio_channel_socket_connect_sync(ioc, addr, &err);
 
-    object_unref(OBJECT(ioc));
-    return ret;
+    qio_task_set_error(task, err);
 }
 
 
@@ -219,20 +215,16 @@ int qio_channel_socket_listen_sync(QIOChannelSocket *ioc,
 }
 
 
-static int qio_channel_socket_listen_worker(QIOTask *task,
-                                            Error **errp,
-                                            gpointer opaque)
+static void qio_channel_socket_listen_worker(QIOTask *task,
+                                             gpointer opaque)
 {
     QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
     SocketAddress *addr = opaque;
-    int ret;
+    Error *err = NULL;
 
-    ret = qio_channel_socket_listen_sync(ioc,
-                                         addr,
-                                         errp);
+    qio_channel_socket_listen_sync(ioc, addr, &err);
 
-    object_unref(OBJECT(ioc));
-    return ret;
+    qio_task_set_error(task, err);
 }
 
 
@@ -295,22 +287,18 @@ static void qio_channel_socket_dgram_worker_free(gpointer opaque)
     g_free(data);
 }
 
-static int qio_channel_socket_dgram_worker(QIOTask *task,
-                                           Error **errp,
-                                           gpointer opaque)
+static void qio_channel_socket_dgram_worker(QIOTask *task,
+                                            gpointer opaque)
 {
     QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
     struct QIOChannelSocketDGramWorkerData *data = opaque;
-    int ret;
+    Error *err = NULL;
 
     /* socket_dgram() blocks in DNS lookups, so we must use a thread */
-    ret = qio_channel_socket_dgram_sync(ioc,
-                                        data->localAddr,
-                                        data->remoteAddr,
-                                        errp);
+    qio_channel_socket_dgram_sync(ioc, data->localAddr,
+                                  data->remoteAddr, &err);
 
-    object_unref(OBJECT(ioc));
-    return ret;
+    qio_task_set_error(task, err);
 }
 
 
diff --git a/io/channel-tls.c b/io/channel-tls.c
index d24dc8c613..f25ab0ae53 100644
--- a/io/channel-tls.c
+++ b/io/channel-tls.c
@@ -153,8 +153,9 @@ static void qio_channel_tls_handshake_task(QIOChannelTLS *ioc,
 
     if (qcrypto_tls_session_handshake(ioc->session, &err) < 0) {
         trace_qio_channel_tls_handshake_fail(ioc);
-        qio_task_abort(task, err);
-        goto cleanup;
+        qio_task_set_error(task, err);
+        qio_task_complete(task);
+        return;
     }
 
     status = qcrypto_tls_session_get_handshake_status(ioc->session);
@@ -163,10 +164,10 @@ static void qio_channel_tls_handshake_task(QIOChannelTLS *ioc,
         if (qcrypto_tls_session_check_credentials(ioc->session,
                                                   &err) < 0) {
             trace_qio_channel_tls_credentials_deny(ioc);
-            qio_task_abort(task, err);
-            goto cleanup;
+            qio_task_set_error(task, err);
+        } else {
+            trace_qio_channel_tls_credentials_allow(ioc);
         }
-        trace_qio_channel_tls_credentials_allow(ioc);
         qio_task_complete(task);
     } else {
         GIOCondition condition;
@@ -183,9 +184,6 @@ static void qio_channel_tls_handshake_task(QIOChannelTLS *ioc,
                               task,
                               NULL);
     }
-
- cleanup:
-    error_free(err);
 }
 
 
@@ -200,8 +198,6 @@ static gboolean qio_channel_tls_handshake_io(QIOChannel *ioc,
     qio_channel_tls_handshake_task(
        tioc, task);
 
-    object_unref(OBJECT(tioc));
-
     return FALSE;
 }
 
diff --git a/io/channel-websock.c b/io/channel-websock.c
index f45bced82a..e47279a1ae 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -279,8 +279,8 @@ static gboolean qio_channel_websock_handshake_send(QIOChannel *ioc,
 
     if (ret < 0) {
         trace_qio_channel_websock_handshake_fail(ioc);
-        qio_task_abort(task, err);
-        error_free(err);
+        qio_task_set_error(task, err);
+        qio_task_complete(task);
         return FALSE;
     }
 
@@ -307,8 +307,8 @@ static gboolean qio_channel_websock_handshake_io(QIOChannel *ioc,
     ret = qio_channel_websock_handshake_read(wioc, &err);
     if (ret < 0) {
         trace_qio_channel_websock_handshake_fail(ioc);
-        qio_task_abort(task, err);
-        error_free(err);
+        qio_task_set_error(task, err);
+        qio_task_complete(task);
         return FALSE;
     }
     if (ret == 0) {
diff --git a/io/dns-resolver.c b/io/dns-resolver.c
new file mode 100644
index 0000000000..0ac6b23c02
--- /dev/null
+++ b/io/dns-resolver.c
@@ -0,0 +1,276 @@
+/*
+ * QEMU DNS resolver
+ *
+ * Copyright (c) 2016 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "io/dns-resolver.h"
+#include "qapi/clone-visitor.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "qemu/cutils.h"
+
+#ifndef AI_NUMERICSERV
+# define AI_NUMERICSERV 0
+#endif
+
+static QIODNSResolver *instance;
+static GOnce instance_init = G_ONCE_INIT;
+
+static gpointer qio_dns_resolve_init_instance(gpointer unused G_GNUC_UNUSED)
+{
+    instance = QIO_DNS_RESOLVER(object_new(TYPE_QIO_DNS_RESOLVER));
+    return NULL;
+}
+
+QIODNSResolver *qio_dns_resolver_get_instance(void)
+{
+    g_once(&instance_init, qio_dns_resolve_init_instance, NULL);
+    return instance;
+}
+
+static int qio_dns_resolver_lookup_sync_inet(QIODNSResolver *resolver,
+                                             SocketAddress *addr,
+                                             size_t *naddrs,
+                                             SocketAddress ***addrs,
+                                             Error **errp)
+{
+    struct addrinfo ai, *res, *e;
+    InetSocketAddress *iaddr = addr->u.inet.data;
+    char port[33];
+    char uaddr[INET6_ADDRSTRLEN + 1];
+    char uport[33];
+    int rc;
+    Error *err = NULL;
+    size_t i;
+
+    *naddrs = 0;
+    *addrs = NULL;
+
+    memset(&ai, 0, sizeof(ai));
+    ai.ai_flags = AI_PASSIVE;
+    if (iaddr->has_numeric && iaddr->numeric) {
+        ai.ai_flags |= AI_NUMERICHOST | AI_NUMERICSERV;
+    }
+    ai.ai_family = inet_ai_family_from_address(iaddr, &err);
+    ai.ai_socktype = SOCK_STREAM;
+
+    if (err) {
+        error_propagate(errp, err);
+        return -1;
+    }
+
+    if (iaddr->host == NULL) {
+        error_setg(errp, "host not specified");
+        return -1;
+    }
+    if (iaddr->port != NULL) {
+        pstrcpy(port, sizeof(port), iaddr->port);
+    } else {
+        port[0] = '\0';
+    }
+
+    rc = getaddrinfo(strlen(iaddr->host) ? iaddr->host : NULL,
+                     strlen(port) ? port : NULL, &ai, &res);
+    if (rc != 0) {
+        error_setg(errp, "address resolution failed for %s:%s: %s",
+                   iaddr->host, port, gai_strerror(rc));
+        return -1;
+    }
+
+    for (e = res; e != NULL; e = e->ai_next) {
+        (*naddrs)++;
+    }
+
+    *addrs = g_new0(SocketAddress *, *naddrs);
+
+    /* create socket + bind */
+    for (i = 0, e = res; e != NULL; i++, e = e->ai_next) {
+        SocketAddress *newaddr = g_new0(SocketAddress, 1);
+        InetSocketAddress *newiaddr = g_new0(InetSocketAddress, 1);
+        newaddr->u.inet.data = newiaddr;
+        newaddr->type = SOCKET_ADDRESS_KIND_INET;
+
+        getnameinfo((struct sockaddr *)e->ai_addr, e->ai_addrlen,
+                    uaddr, INET6_ADDRSTRLEN, uport, 32,
+                    NI_NUMERICHOST | NI_NUMERICSERV);
+
+        *newiaddr = (InetSocketAddress){
+            .host = g_strdup(uaddr),
+            .port = g_strdup(uport),
+            .has_numeric = true,
+            .numeric = true,
+            .has_to = iaddr->has_to,
+            .to = iaddr->to,
+            .has_ipv4 = false,
+            .has_ipv6 = false,
+        };
+
+        (*addrs)[i] = newaddr;
+    }
+    freeaddrinfo(res);
+    return 0;
+}
+
+
+static int qio_dns_resolver_lookup_sync_nop(QIODNSResolver *resolver,
+                                            SocketAddress *addr,
+                                            size_t *naddrs,
+                                            SocketAddress ***addrs,
+                                            Error **errp)
+{
+    *naddrs = 1;
+    *addrs = g_new0(SocketAddress *, 1);
+    (*addrs)[0] = QAPI_CLONE(SocketAddress, addr);
+
+    return 0;
+}
+
+
+int qio_dns_resolver_lookup_sync(QIODNSResolver *resolver,
+                                 SocketAddress *addr,
+                                 size_t *naddrs,
+                                 SocketAddress ***addrs,
+                                 Error **errp)
+{
+    switch (addr->type) {
+    case SOCKET_ADDRESS_KIND_INET:
+        return qio_dns_resolver_lookup_sync_inet(resolver,
+                                                 addr,
+                                                 naddrs,
+                                                 addrs,
+                                                 errp);
+
+    case SOCKET_ADDRESS_KIND_UNIX:
+    case SOCKET_ADDRESS_KIND_VSOCK:
+        return qio_dns_resolver_lookup_sync_nop(resolver,
+                                                addr,
+                                                naddrs,
+                                                addrs,
+                                                errp);
+
+    default:
+        error_setg(errp, "Unknown socket address kind");
+        return -1;
+    }
+}
+
+
+struct QIODNSResolverLookupData {
+    SocketAddress *addr;
+    SocketAddress **addrs;
+    size_t naddrs;
+};
+
+
+static void qio_dns_resolver_lookup_data_free(gpointer opaque)
+{
+    struct QIODNSResolverLookupData *data = opaque;
+    size_t i;
+
+    qapi_free_SocketAddress(data->addr);
+    for (i = 0; i < data->naddrs; i++) {
+        qapi_free_SocketAddress(data->addrs[i]);
+    }
+
+    g_free(data->addrs);
+    g_free(data);
+}
+
+
+static void qio_dns_resolver_lookup_worker(QIOTask *task,
+                                           gpointer opaque)
+{
+    QIODNSResolver *resolver = QIO_DNS_RESOLVER(qio_task_get_source(task));
+    struct QIODNSResolverLookupData *data = opaque;
+    Error *err = NULL;
+
+    qio_dns_resolver_lookup_sync(resolver,
+                                 data->addr,
+                                 &data->naddrs,
+                                 &data->addrs,
+                                 &err);
+    if (err) {
+        qio_task_set_error(task, err);
+    } else {
+        qio_task_set_result_pointer(task, opaque, NULL);
+    }
+
+    object_unref(OBJECT(resolver));
+}
+
+
+void qio_dns_resolver_lookup_async(QIODNSResolver *resolver,
+                                   SocketAddress *addr,
+                                   QIOTaskFunc func,
+                                   gpointer opaque,
+                                   GDestroyNotify notify)
+{
+    QIOTask *task;
+    struct QIODNSResolverLookupData *data =
+        g_new0(struct QIODNSResolverLookupData, 1);
+
+    data->addr = QAPI_CLONE(SocketAddress, addr);
+
+    task = qio_task_new(OBJECT(resolver), func, opaque, notify);
+
+    qio_task_run_in_thread(task,
+                           qio_dns_resolver_lookup_worker,
+                           data,
+                           qio_dns_resolver_lookup_data_free);
+}
+
+
+void qio_dns_resolver_lookup_result(QIODNSResolver *resolver,
+                                    QIOTask *task,
+                                    size_t *naddrs,
+                                    SocketAddress ***addrs)
+{
+    struct QIODNSResolverLookupData *data =
+        qio_task_get_result_pointer(task);
+    size_t i;
+
+    *naddrs = 0;
+    *addrs = NULL;
+    if (!data) {
+        return;
+    }
+
+    *naddrs = data->naddrs;
+    *addrs = g_new0(SocketAddress *, data->naddrs);
+    for (i = 0; i < data->naddrs; i++) {
+        (*addrs)[i] = QAPI_CLONE(SocketAddress, data->addrs[i]);
+    }
+}
+
+
+static const TypeInfo qio_dns_resolver_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_QIO_DNS_RESOLVER,
+    .instance_size = sizeof(QIODNSResolver),
+    .class_size = sizeof(QIODNSResolverClass),
+};
+
+
+static void qio_dns_resolver_register_types(void)
+{
+    type_register_static(&qio_dns_resolver_info);
+}
+
+
+type_init(qio_dns_resolver_register_types);
diff --git a/io/task.c b/io/task.c
index c7f97a9b16..60bf1a94d5 100644
--- a/io/task.c
+++ b/io/task.c
@@ -29,6 +29,9 @@ struct QIOTask {
     QIOTaskFunc func;
     gpointer opaque;
     GDestroyNotify destroy;
+    Error *err;
+    gpointer result;
+    GDestroyNotify destroyResult;
 };
 
 
@@ -57,6 +60,12 @@ static void qio_task_free(QIOTask *task)
     if (task->destroy) {
         task->destroy(task->opaque);
     }
+    if (task->destroyResult) {
+        task->destroyResult(task->result);
+    }
+    if (task->err) {
+        error_free(task->err);
+    }
     object_unref(task->source);
 
     g_free(task);
@@ -68,8 +77,6 @@ struct QIOTaskThreadData {
     QIOTaskWorker worker;
     gpointer opaque;
     GDestroyNotify destroy;
-    Error *err;
-    int ret;
 };
 
 
@@ -78,13 +85,8 @@ static gboolean gio_task_thread_result(gpointer opaque)
     struct QIOTaskThreadData *data = opaque;
 
     trace_qio_task_thread_result(data->task);
-    if (data->ret == 0) {
-        qio_task_complete(data->task);
-    } else {
-        qio_task_abort(data->task, data->err);
-    }
+    qio_task_complete(data->task);
 
-    error_free(data->err);
     if (data->destroy) {
         data->destroy(data->opaque);
     }
@@ -100,10 +102,7 @@ static gpointer qio_task_thread_worker(gpointer opaque)
     struct QIOTaskThreadData *data = opaque;
 
     trace_qio_task_thread_run(data->task);
-    data->ret = data->worker(data->task, &data->err, data->opaque);
-    if (data->ret < 0 && data->err == NULL) {
-        error_setg(&data->err, "Task worker failed but did not set an error");
-    }
+    data->worker(data->task, data->opaque);
 
     /* We're running in the background thread, and must only
      * ever report the task results in the main event loop
@@ -140,22 +139,47 @@ void qio_task_run_in_thread(QIOTask *task,
 
 void qio_task_complete(QIOTask *task)
 {
-    task->func(task->source, NULL, task->opaque);
+    task->func(task, task->opaque);
     trace_qio_task_complete(task);
     qio_task_free(task);
 }
 
-void qio_task_abort(QIOTask *task,
-                    Error *err)
+
+void qio_task_set_error(QIOTask *task,
+                        Error *err)
 {
-    task->func(task->source, err, task->opaque);
-    trace_qio_task_abort(task);
-    qio_task_free(task);
+    error_propagate(&task->err, err);
+}
+
+
+bool qio_task_propagate_error(QIOTask *task,
+                              Error **errp)
+{
+    if (task->err) {
+        error_propagate(errp, task->err);
+        return true;
+    }
+
+    return false;
+}
+
+
+void qio_task_set_result_pointer(QIOTask *task,
+                                 gpointer result,
+                                 GDestroyNotify destroy)
+{
+    task->result = result;
+    task->destroyResult = destroy;
+}
+
+
+gpointer qio_task_get_result_pointer(QIOTask *task)
+{
+    return task->result;
 }
 
 
 Object *qio_task_get_source(QIOTask *task)
 {
-    object_ref(task->source);
     return task->source;
 }
diff --git a/io/trace-events b/io/trace-events
index e31b596ca1..ff993bef45 100644
--- a/io/trace-events
+++ b/io/trace-events
@@ -3,7 +3,6 @@
 # io/task.c
 qio_task_new(void *task, void *source, void *func, void *opaque) "Task new task=%p source=%p func=%p opaque=%p"
 qio_task_complete(void *task) "Task complete task=%p"
-qio_task_abort(void *task) "Task abort task=%p"
 qio_task_thread_start(void *task, void *worker, void *opaque) "Task thread start task=%p worker=%p opaque=%p"
 qio_task_thread_run(void *task) "Task thread run task=%p"
 qio_task_thread_exit(void *task) "Task thread exit task=%p"
diff --git a/migration/socket.c b/migration/socket.c
index 11f80b119b..13966f1d26 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -70,22 +70,23 @@ static void socket_connect_data_free(void *opaque)
     g_free(data);
 }
 
-static void socket_outgoing_migration(Object *src,
-                                      Error *err,
+static void socket_outgoing_migration(QIOTask *task,
                                       gpointer opaque)
 {
     struct SocketConnectData *data = opaque;
-    QIOChannel *sioc = QIO_CHANNEL(src);
+    QIOChannel *sioc = QIO_CHANNEL(qio_task_get_source(task));
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         trace_migration_socket_outgoing_error(error_get_pretty(err));
         data->s->to_dst_file = NULL;
         migrate_fd_error(data->s, err);
+        error_free(err);
     } else {
         trace_migration_socket_outgoing_connected(data->hostname);
         migration_channel_connect(data->s, sioc, data->hostname);
     }
-    object_unref(src);
+    object_unref(OBJECT(sioc));
 }
 
 static void socket_start_outgoing_migration(MigrationState *s,
diff --git a/migration/tls.c b/migration/tls.c
index 49ca9a8930..203c11d025 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -61,15 +61,15 @@ migration_tls_get_creds(MigrationState *s,
 }
 
 
-static void migration_tls_incoming_handshake(Object *src,
-                                             Error *err,
+static void migration_tls_incoming_handshake(QIOTask *task,
                                              gpointer opaque)
 {
-    QIOChannel *ioc = QIO_CHANNEL(src);
+    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         trace_migration_tls_incoming_handshake_error(error_get_pretty(err));
-        error_report("%s", error_get_pretty(err));
+        error_report_err(err);
     } else {
         trace_migration_tls_incoming_handshake_complete();
         migration_channel_process_incoming(migrate_get_current(), ioc);
@@ -107,17 +107,18 @@ void migration_tls_channel_process_incoming(MigrationState *s,
 }
 
 
-static void migration_tls_outgoing_handshake(Object *src,
-                                             Error *err,
+static void migration_tls_outgoing_handshake(QIOTask *task,
                                              gpointer opaque)
 {
     MigrationState *s = opaque;
-    QIOChannel *ioc = QIO_CHANNEL(src);
+    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         trace_migration_tls_outgoing_handshake_error(error_get_pretty(err));
         s->to_dst_file = NULL;
         migrate_fd_error(s, err);
+        error_free(err);
     } else {
         trace_migration_tls_outgoing_handshake_complete();
         migration_channel_connect(s, ioc, NULL);
diff --git a/nbd/common.c b/nbd/common.c
index b583a4f4cf..a5f39ea58e 100644
--- a/nbd/common.c
+++ b/nbd/common.c
@@ -78,15 +78,13 @@ ssize_t nbd_wr_syncv(QIOChannel *ioc,
 }
 
 
-void nbd_tls_handshake(Object *src,
-                       Error *err,
+void nbd_tls_handshake(QIOTask *task,
                        void *opaque)
 {
     struct NBDTLSHandshakeData *data = opaque;
 
-    if (err) {
-        TRACE("TLS failed %s", error_get_pretty(err));
-        data->error = error_copy(err);
+    if (qio_task_propagate_error(task, &data->error)) {
+        TRACE("TLS failed %s", error_get_pretty(data->error));
     }
     data->complete = true;
     g_main_loop_quit(data->loop);
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index eee20abc25..f43d990a05 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -120,8 +120,7 @@ struct NBDTLSHandshakeData {
 };
 
 
-void nbd_tls_handshake(Object *src,
-                       Error *err,
+void nbd_tls_handshake(QIOTask *task,
                        void *opaque);
 
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index ddc878390e..ac55f4a41b 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3983,6 +3983,10 @@
 #
 # @port: port part of the address, or lowest port if @to is present
 #
+# @numeric: #optional true if the host/port are guaranteed to be numeric,
+#           false if name resolution should be attempted. Defaults to false.
+#           (Since 2.9)
+#
 # @to: highest port to try
 #
 # @ipv4: whether to accept IPv4 addresses, default try both IPv4 and IPv6
@@ -3997,6 +4001,7 @@
   'data': {
     'host': 'str',
     'port': 'str',
+    '*numeric':  'bool',
     '*to': 'uint16',
     '*ipv4': 'bool',
     '*ipv6': 'bool' } }
diff --git a/qemu-char.c b/qemu-char.c
index 676944a765..d8da1677ff 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -3277,14 +3277,13 @@ static void tcp_chr_telnet_init(CharDriverState *chr)
 }
 
 
-static void tcp_chr_tls_handshake(Object *source,
-                                  Error *err,
+static void tcp_chr_tls_handshake(QIOTask *task,
                                   gpointer user_data)
 {
     CharDriverState *chr = user_data;
     TCPCharDriver *s = chr->opaque;
 
-    if (err) {
+    if (qio_task_propagate_error(task, NULL)) {
         tcp_chr_disconnect(chr);
     } else {
         if (s->do_telnetopt) {
@@ -3492,20 +3491,23 @@ static void tcp_chr_free(CharDriverState *chr)
 }
 
 
-static void qemu_chr_socket_connected(Object *src, Error *err, void *opaque)
+static void qemu_chr_socket_connected(QIOTask *task, void *opaque)
 {
-    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(src);
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
     CharDriverState *chr = opaque;
     TCPCharDriver *s = chr->opaque;
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         check_report_connect_error(chr, err);
-        object_unref(src);
-        return;
+        error_free(err);
+        goto cleanup;
     }
 
     s->connect_err_reported = false;
     tcp_chr_new_client(chr, sioc);
+
+ cleanup:
     object_unref(OBJECT(sioc));
 }
 
diff --git a/tests/test-io-channel-socket.c b/tests/test-io-channel-socket.c
index aa88c3cf45..aaa9116fb7 100644
--- a/tests/test-io-channel-socket.c
+++ b/tests/test-io-channel-socket.c
@@ -156,12 +156,11 @@ struct TestIOChannelData {
 };
 
 
-static void test_io_channel_complete(Object *src,
-                                     Error *err,
+static void test_io_channel_complete(QIOTask *task,
                                      gpointer opaque)
 {
     struct TestIOChannelData *data = opaque;
-    data->err = err != NULL;
+    data->err = qio_task_propagate_error(task, NULL);
     g_main_loop_quit(data->loop);
 }
 
diff --git a/tests/test-io-channel-tls.c b/tests/test-io-channel-tls.c
index bd3ae2bf7a..8eaa208e1b 100644
--- a/tests/test-io-channel-tls.c
+++ b/tests/test-io-channel-tls.c
@@ -53,14 +53,13 @@ struct QIOChannelTLSHandshakeData {
     bool failed;
 };
 
-static void test_tls_handshake_done(Object *source,
-                                    Error *err,
+static void test_tls_handshake_done(QIOTask *task,
                                     gpointer opaque)
 {
     struct QIOChannelTLSHandshakeData *data = opaque;
 
     data->finished = true;
-    data->failed = err != NULL;
+    data->failed = qio_task_propagate_error(task, NULL);
 }
 
 
diff --git a/tests/test-io-task.c b/tests/test-io-task.c
index e091c12e10..ff62272d5f 100644
--- a/tests/test-io-task.c
+++ b/tests/test-io-task.c
@@ -50,14 +50,13 @@ struct TestTaskData {
 };
 
 
-static void task_callback(Object *source,
-                          Error *err,
+static void task_callback(QIOTask *task,
                           gpointer opaque)
 {
     struct TestTaskData *data = opaque;
 
-    data->source = source;
-    data->err = err;
+    data->source = qio_task_get_source(task);
+    qio_task_propagate_error(task, &data->err);
 }
 
 
@@ -76,7 +75,6 @@ static void test_task_complete(void)
     g_assert(obj == src);
 
     object_unref(obj);
-    object_unref(src);
 
     g_assert(data.source == obj);
     g_assert(data.err == NULL);
@@ -121,9 +119,9 @@ static void test_task_failure(void)
 
     error_setg(&err, "Some error");
 
-    qio_task_abort(task, err);
+    qio_task_set_error(task, err);
+    qio_task_complete(task);
 
-    error_free(err);
     object_unref(obj);
 
     g_assert(data.source == obj);
@@ -142,31 +140,28 @@ struct TestThreadWorkerData {
     GMainLoop *loop;
 };
 
-static int test_task_thread_worker(QIOTask *task,
-                                   Error **errp,
-                                   gpointer opaque)
+static void test_task_thread_worker(QIOTask *task,
+                                    gpointer opaque)
 {
     struct TestThreadWorkerData *data = opaque;
 
     data->worker = g_thread_self();
 
     if (data->fail) {
-        error_setg(errp, "Testing fail");
-        return -1;
+        Error *err = NULL;
+        error_setg(&err, "Testing fail");
+        qio_task_set_error(task, err);
     }
-
-    return 0;
 }
 
 
-static void test_task_thread_callback(Object *source,
-                                      Error *err,
+static void test_task_thread_callback(QIOTask *task,
                                       gpointer opaque)
 {
     struct TestThreadWorkerData *data = opaque;
 
-    data->source = source;
-    data->err = err;
+    data->source = qio_task_get_source(task);
+    qio_task_propagate_error(task, &data->err);
 
     data->complete = g_thread_self();
 
diff --git a/ui/vnc-auth-vencrypt.c b/ui/vnc-auth-vencrypt.c
index c0c29a5119..ffaab57550 100644
--- a/ui/vnc-auth-vencrypt.c
+++ b/ui/vnc-auth-vencrypt.c
@@ -65,16 +65,17 @@ static void start_auth_vencrypt_subauth(VncState *vs)
     }
 }
 
-static void vnc_tls_handshake_done(Object *source,
-                                   Error *err,
+static void vnc_tls_handshake_done(QIOTask *task,
                                    gpointer user_data)
 {
     VncState *vs = user_data;
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         VNC_DEBUG("Handshake failed %s\n",
                   error_get_pretty(err));
         vnc_client_error(vs);
+        error_free(err);
     } else {
         vs->ioc_tag = qio_channel_add_watch(
             vs->ioc, G_IO_IN | G_IO_OUT, vnc_client_io, vs, NULL);
diff --git a/ui/vnc-ws.c b/ui/vnc-ws.c
index bffb484a8d..f530cd5474 100644
--- a/ui/vnc-ws.c
+++ b/ui/vnc-ws.c
@@ -24,15 +24,16 @@
 #include "io/channel-websock.h"
 #include "qemu/bswap.h"
 
-static void vncws_tls_handshake_done(Object *source,
-                                     Error *err,
+static void vncws_tls_handshake_done(QIOTask *task,
                                      gpointer user_data)
 {
     VncState *vs = user_data;
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         VNC_DEBUG("Handshake failed %s\n", error_get_pretty(err));
         vnc_client_error(vs);
+        error_free(err);
     } else {
         VNC_DEBUG("TLS handshake complete, starting websocket handshake\n");
         vs->ioc_tag = qio_channel_add_watch(
@@ -83,15 +84,16 @@ gboolean vncws_tls_handshake_io(QIOChannel *ioc G_GNUC_UNUSED,
 }
 
 
-static void vncws_handshake_done(Object *source,
-                                 Error *err,
+static void vncws_handshake_done(QIOTask *task,
                                  gpointer user_data)
 {
     VncState *vs = user_data;
+    Error *err = NULL;
 
-    if (err) {
+    if (qio_task_propagate_error(task, &err)) {
         VNC_DEBUG("Websock handshake failed %s\n", error_get_pretty(err));
         vnc_client_error(vs);
+        error_free(err);
     } else {
         VNC_DEBUG("Websock handshake complete, starting VNC protocol\n");
         vnc_start_protocol(vs);
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index fe1d07aaef..7c120c45ce 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -38,6 +38,10 @@
 # define AI_V4MAPPED 0
 #endif
 
+#ifndef AI_NUMERICSERV
+# define AI_NUMERICSERV 0
+#endif
+
 
 static int inet_getport(struct addrinfo *e)
 {
@@ -110,8 +114,8 @@ NetworkAddressFamily inet_netfamily(int family)
  * outside scope of this method and not currently handled by
  * callers at all.
  */
-static int inet_ai_family_from_address(InetSocketAddress *addr,
-                                       Error **errp)
+int inet_ai_family_from_address(InetSocketAddress *addr,
+                                Error **errp)
 {
     if (addr->has_ipv6 && addr->has_ipv4 &&
         !addr->ipv6 && !addr->ipv4) {
@@ -141,6 +145,9 @@ static int inet_listen_saddr(InetSocketAddress *saddr,
 
     memset(&ai,0, sizeof(ai));
     ai.ai_flags = AI_PASSIVE;
+    if (saddr->has_numeric && saddr->numeric) {
+        ai.ai_flags |= AI_NUMERICHOST | AI_NUMERICSERV;
+    }
     ai.ai_family = inet_ai_family_from_address(saddr, &err);
     ai.ai_socktype = SOCK_STREAM;