[Qemu-devel] [RFC PATCH 09/13] qmp: add NBD server commands

[Paolo Bonzini <pbonzini@redhat.com>]

Adding an NBD server inside QEMU is trivial, since all the logic is
in nbd.c and can be shared easily between qemu-nbd and QEMU itself.
The main difference is that qemu-nbd serves a single unnamed export,
while QEMU serves named exports.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Makefile.objs    |  2 +-
 blockdev-nbd.c   | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qapi-schema.json | 69 +++++++++++++++++++++++++++++++++++++++++
 qmp-commands.hx  | 16 ++++++++++
 4 file modificati, 179 inserzioni(+). 1 rimozione(-)
 create mode 100644 blockdev-nbd.c

diff --git a/Makefile.objs b/Makefile.objs
index 4412757..c42affc 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -59,7 +59,7 @@ endif
 # suppress *all* target specific code in case of system emulation, i.e. a
 # single QEMU executable should support all CPUs and machines.
 
-common-obj-y = $(block-obj-y) blockdev.o
+common-obj-y = $(block-obj-y) blockdev.o blockdev-nbd.o
 common-obj-y += net.o net/
 common-obj-y += qom/
 common-obj-y += readline.o console.o cursor.o
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
new file mode 100644
index 0000000..5a415be
--- /dev/null
+++ b/blockdev-nbd.c
@@ -0,0 +1,93 @@
+/*
+ * QEMU host block devices
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "blockdev.h"
+#include "hw/block-common.h"
+#include "monitor.h"
+#include "qerror.h"
+#include "sysemu.h"
+#include "qmp-commands.h"
+#include "trace.h"
+#include "nbd.h"
+#include "qemu_socket.h"
+
+static int server_fd = -1;
+
+static void nbd_accept(void *opaque)
+{
+    struct sockaddr_in addr;
+    socklen_t addr_len = sizeof(addr);
+
+    int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
+    if (fd >= 0) {
+        nbd_client_new(NULL, fd, NULL);
+    }
+}
+
+static void nbd_server_start(QemuOpts *opts, Error **errp)
+{
+    if (server_fd != -1) {
+        /* TODO: error */
+        return;
+    }
+
+    server_fd = inet_listen_opts(opts, 0, errp);
+    if (server_fd != -1) {
+        qemu_set_fd_handler2(server_fd, NULL, nbd_accept, NULL, NULL);
+    }
+}
+
+void qmp_nbd_server_start(IPSocketAddress *addr, Error **errp)
+{
+    QemuOpts *opts;
+
+    opts = qemu_opts_create(&socket_opts, NULL, 0, NULL);
+    qemu_opt_set(opts, "host", addr->host);
+    qemu_opt_set(opts, "port", addr->port);
+
+    addr->ipv4 |= !addr->has_ipv4;
+    addr->ipv6 |= !addr->has_ipv6;
+    if (!addr->ipv4 || !addr->ipv6) {
+        qemu_opt_set_bool(opts, "ipv4", addr->ipv4);
+        qemu_opt_set_bool(opts, "ipv6", addr->ipv6);
+    }
+
+    nbd_server_start(opts, errp);
+    qemu_opts_del(opts);
+}
+
+
+void qmp_nbd_server_add(const char *device, bool has_writable, bool writable,
+                        Error **errp)
+{
+    BlockDriverState *bs;
+    NBDExport *exp;
+
+    bs = bdrv_find(device);
+    if (!bs) {
+        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        return;
+    }
+
+    if (nbd_export_find(bdrv_get_device_name(bs))) {
+        /* TODO: error */
+        return;
+    }
+
+    exp = nbd_export_new(bs, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY);
+    nbd_export_set_name(exp, device);
+}
+
+void qmp_nbd_server_stop(Error **errp)
+{
+    nbd_export_close_all();
+    qemu_set_fd_handler2(server_fd, NULL, NULL, NULL, NULL);
+    close(server_fd);
+    server_fd = -1;
+}
diff --git a/qapi-schema.json b/qapi-schema.json
index 3d2b2d1..d792d2c 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2275,6 +2275,30 @@
     'opts': 'NetClientOptions' } }
 
 ##
+# @IPSocketAddress
+#
+# Captures the destination address of an IP socket
+#
+# @host: host part of the address
+#
+# @port: port part of the address, or lowest port if @to is present
+#
+# @to: highest port to try
+#
+# @ipv4: whether to accept IPv4 addresses, default try both IPv4 and IPv6
+#
+# @ipv6: whether to accept IPv6 addresses, default try both IPv4 and IPv6
+#
+# Since 1.3
+##
+{ 'type': 'IPSocketAddress',
+  'data': {
+    'host': 'str',
+    'port': 'str',
+    '*ipv4': 'bool',
+    '*ipv6': 'bool' } }
+
+##
 # @getfd:
 #
 # Receive a file descriptor via SCM rights and assign it a name
@@ -2454,3 +2478,46 @@
 #
 ##
 { 'command': 'query-fdsets', 'returns': ['FdsetInfo'] }
+
+##
+# @nbd-server-start:
+#
+# Start an NBD server listening on the given host and port.
+#
+# @addr: Interface on which to listen, nothing for all interfaces.
+#
+# Since: 1.3.0
+#
+##
+{ 'command': 'nbd-server-start',
+  'data': { 'addr': 'IPSocketAddress' } }
+
+##
+# @nbd-server-add:
+#
+# Export a device to QEMU's embedded NBD server.
+#
+# @device: Block device to be exported
+#
+# @writable: Whether clients should be able to write to the device via the
+#     NBD connection (default false).
+#
+# Returns: error if the device is already marked for export.
+#
+# Since: 1.3.0
+#
+##
+{ 'command': 'nbd-server-add', 'data': {'device': 'str', '*writable': 'bool'} }
+
+##
+# @nbd-server-stop:
+#
+# Stop QEMU's embedded NBD server, and unregister all devices previously
+# added via nbd-server-add
+#
+# Returns: error if the server is already running.
+#
+# Since: 1.3.0
+#
+##
+{ 'command': 'nbd-server-stop' }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 2ce4ce6..1f7d6fe 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -2481,6 +2481,22 @@ EQMP
     },
 
     {
+        .name       = "nbd-server-start",
+        .args_type  = "addr:q",
+        .mhandler.cmd_new = qmp_marshal_input_nbd_server_start,
+    },
+    {
+        .name       = "nbd-server-add",
+        .args_type  = "device:B,writable:b?",
+        .mhandler.cmd_new = qmp_marshal_input_nbd_server_add,
+    },
+    {
+        .name       = "nbd-server-stop",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_nbd_server_stop,
+    },
+
+    {
         .name       = "change-vnc-password",
         .args_type  = "password:s",
         .mhandler.cmd_new = qmp_marshal_input_change_vnc_password,
-- 
1.7.11.2