[Qemu-devel] [PATCH 5/9] filter: add netbuffer plugin

[Yang Hongyang]

This could be used by VM FT solutions like Macrocheckpointing,
to buffer/release packets.

Usage:
  -netdev tap,id=bn0  # you can use whatever backend as needed
  -netdev filter,id=f0,backend=bn0
  -netdev filter-buffer,id=p0,filter=f0
  -device e1000,netdev=f0

Will supply a public API to release the buffer. But there's no
callers currently.
To test this feature, it's quite simple, just use
netdev_add filter-buffer,id=p0,filter=f0
to buffer packets,
netdev_del p0
will release packets.

Signed-off-by: Yang Hongyang <address@hidden>
---
 net/Makefile.objs   |  1 +
 net/clients.h       |  3 ++
 net/filter-buffer.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 net/net.c           |  2 ++
 qapi-schema.json    | 20 +++++++++++++-
 5 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 net/filter-buffer.c

diff --git a/net/Makefile.objs b/net/Makefile.objs
index 914aec0..5fa2f97 100644
--- a/net/Makefile.objs
+++ b/net/Makefile.objs
@@ -14,3 +14,4 @@ common-obj-$(CONFIG_SLIRP) += slirp.o
 common-obj-$(CONFIG_VDE) += vde.o
 common-obj-$(CONFIG_NETMAP) += netmap.o
 common-obj-y += filter.o
+common-obj-y += filter-buffer.o
diff --git a/net/clients.h b/net/clients.h
index bcfb34b..7cc60f2 100644
--- a/net/clients.h
+++ b/net/clients.h
@@ -65,4 +65,7 @@ int net_init_vhost_user(const NetClientOptions *opts, const 
char *name,
 int net_init_filter(const NetClientOptions *opts, const char *name,
                     NetClientState *peer, Error **errp);
 
+int net_init_filter_buffer(const NetClientOptions *opts, const char *name,
+                           NetClientState *peer, Error **errp);
+
 #endif /* QEMU_NET_CLIENTS_H */
diff --git a/net/filter-buffer.c b/net/filter-buffer.c
new file mode 100644
index 0000000..15ac903
--- /dev/null
+++ b/net/filter-buffer.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Author: Yang Hongyang <address@hidden>
+ *
+ * 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 "net/net.h"
+#include "net/queue.h"
+#include "clients.h"
+#include "qemu-common.h"
+#include "qemu/error-report.h"
+#include "net/filter.h"
+
+typedef struct FILTERBUFFERState {
+    NetClientState nc;
+    NetClientState *filter;
+    int interval;
+    NetQueue *inflight_queue;
+} FILTERBUFFERState;
+
+static ssize_t filter_buffer_receive(NetClientState *nc, NetClientState 
*sender,
+                              unsigned flags, const uint8_t *data, size_t size)
+{
+    NetQueue *queue = nc->incoming_queue;
+
+    if (sender->info->type == NET_CLIENT_OPTIONS_KIND_NIC) {
+        /* we only buffer guest output packets */
+        qemu_net_queue_append(queue, sender, flags, data, size, NULL);
+        /* Now that we have buffered the packet, return sucess */
+        return size;
+    }
+
+    return 0;
+}
+
+static void filter_buffer_cleanup(NetClientState *nc)
+{
+    FILTERBUFFERState *s = DO_UPCAST(FILTERBUFFERState, nc, nc);
+    filter_del_plugin(s->filter, nc);
+    return;
+}
+
+
+static NetClientInfo net_filter_buffer_info = {
+    .type = NET_CLIENT_OPTIONS_KIND_FILTER_BUFFER,
+    .size = sizeof(FILTERBUFFERState),
+    .receive_filter = filter_buffer_receive,
+    .cleanup = filter_buffer_cleanup,
+};
+
+int net_init_filter_buffer(const NetClientOptions *opts, const char *name,
+                           NetClientState *peer, Error **errp)
+{
+    NetClientState *nc;
+    FILTERBUFFERState *s;
+    const NetdevFilterBufferOptions *bufferopt;
+    char *filter_id = NULL;
+    NetClientState *filter;
+
+    assert(opts->kind == NET_CLIENT_OPTIONS_KIND_FILTER_BUFFER);
+    bufferopt = opts->filter_buffer;
+    assert(bufferopt->has_filter);
+
+    filter_id = bufferopt->filter;
+    filter = qemu_find_netdev(filter_id);
+    if (!filter) {
+        error_setg(errp, "invalid filter name specified");
+        return -1;
+    }
+
+    nc = qemu_new_net_client(&net_filter_buffer_info, peer, "filter_buffer", 
name);
+    s = DO_UPCAST(FILTERBUFFERState, nc, nc);
+    s->filter = filter;
+    s->interval = bufferopt->has_interval ? bufferopt->interval : 0;
+    filter_add_plugin(filter, nc);
+
+    return 0;
+}
diff --git a/net/net.c b/net/net.c
index 321362f..856a0fe 100644
--- a/net/net.c
+++ b/net/net.c
@@ -58,6 +58,7 @@ const char *host_net_devices[] = {
     "socket",
     "dump",
     "filter",
+    "filter-buffer",
 #ifdef CONFIG_NET_BRIDGE
     "bridge",
 #endif
@@ -907,6 +908,7 @@ static int (* const 
net_client_init_fun[NET_CLIENT_OPTIONS_KIND_MAX])(
     NetClientState *peer, Error **errp) = {
         [NET_CLIENT_OPTIONS_KIND_NIC]       = net_init_nic,
         [NET_CLIENT_OPTIONS_KIND_FILTER]    = net_init_filter,
+        [NET_CLIENT_OPTIONS_KIND_FILTER_BUFFER] = net_init_filter_buffer,
 #ifdef CONFIG_SLIRP
         [NET_CLIENT_OPTIONS_KIND_USER]      = net_init_slirp,
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index 9244c88..62cc54e 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2491,6 +2491,23 @@
     '*backend':       'str' } }
 
 ##
+# @NetdevFilterBufferOptions
+#
+# A net filter buffer plugin
+#
+# @filter: the network filter this plugin attached to.
+#
+# @interval: #optional release packets by interval, if no interval supplied,
+#            will release packets when filter_buffer_release been called.
+#
+# Since 2.5
+##
+{ 'struct': 'NetdevFilterBufferOptions',
+  'data': {
+    '*filter':       'str',
+    '*interval':     'int32' } }
+
+##
 # @NetClientOptions
 #
 # A discriminated record of network device traits.
@@ -2514,7 +2531,8 @@
     'hubport':  'NetdevHubPortOptions',
     'netmap':   'NetdevNetmapOptions',
     'vhost-user': 'NetdevVhostUserOptions',
-    'filter':   'NetdevFilterOptions'} }
+    'filter':   'NetdevFilterOptions',
+    'filter-buffer': 'NetdevFilterBufferOptions' } }
 
 ##
 # @NetLegacy
-- 
1.9.1