[Qemu-devel] [PATCH v5 08/10] netfilter: add a netbuffer filter

[Yang Hongyang <yanghy@cn.fujitsu.com>]

This filter is to buffer/release packets, this feature can be used
when using MicroCheckpointing, or other Remus like VM FT solutions, you
can also use it to simulate the network delay.
It has an interval option, if supplied, this filter will release
packets by interval.

Usage:
 -netdev tap,id=bn0
 -netfilter buffer,id=f0,netdev=bn0,chain=in,interval=1000

NOTE:
 the scale of interval is microsecond.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
---
v5: remove dummy sent_cb
    change interval type from int64 to uint32
    check interval!=0 when initialise
    rename FILTERBUFFERState to FilterBufferState
v4: remove bh
    pass the packet to next filter instead of receiver
v3: check packet's sender and sender->peer when flush it
---
 net/Makefile.objs   |   1 +
 net/filter-buffer.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 net/filter.c        |   2 +
 net/filters.h       |  17 ++++++++
 qapi-schema.json    |  18 +++++++-
 5 files changed, 159 insertions(+), 1 deletion(-)
 create mode 100644 net/filter-buffer.c
 create mode 100644 net/filters.h

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/filter-buffer.c b/net/filter-buffer.c
new file mode 100644
index 0000000..435ae4e
--- /dev/null
+++ b/net/filter-buffer.c
@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Author: Yang Hongyang <yanghy@cn.fujitsu.com>
+ *
+ * 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/filter.h"
+#include "net/queue.h"
+#include "filters.h"
+#include "qemu-common.h"
+#include "qemu/timer.h"
+#include "qemu/iov.h"
+#include "qapi/qmp/qerror.h"
+
+typedef struct FilterBufferState {
+    NetFilterState nf;
+    NetQueue *incoming_queue;
+    uint32_t interval;
+    QEMUTimer release_timer;
+} FilterBufferState;
+
+static void filter_buffer_flush(NetFilterState *nf)
+{
+    FilterBufferState *s = DO_UPCAST(FilterBufferState, nf, nf);
+    NetQueue *queue = s->incoming_queue;
+    NetPacket *packet;
+
+    while (queue && !QTAILQ_EMPTY(&queue->packets)) {
+        packet = QTAILQ_FIRST(&queue->packets);
+        QTAILQ_REMOVE(&queue->packets, packet, entry);
+        queue->nq_count--;
+
+        if (packet->sender && packet->sender->peer) {
+            qemu_netfilter_pass_to_next(nf, packet);
+        }
+
+        /*
+         * now that we pass the packet to next filter, we don't care the
+         * reture value here, because the filter layer or other filter
+         * will take care of this packet
+         */
+        g_free(packet);
+    }
+}
+
+static void filter_buffer_release_timer(void *opaque)
+{
+    FilterBufferState *s = opaque;
+    filter_buffer_flush(&s->nf);
+    timer_mod(&s->release_timer,
+              qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) + s->interval);
+}
+
+/* filter APIs */
+static ssize_t filter_buffer_receive_iov(NetFilterState *nf,
+                                         NetClientState *sender,
+                                         unsigned flags,
+                                         const struct iovec *iov,
+                                         int iovcnt,
+                                         NetPacketSent *sent_cb)
+{
+    FilterBufferState *s = DO_UPCAST(FilterBufferState, nf, nf);
+    NetQueue *queue = s->incoming_queue;
+
+    qemu_net_queue_append_iov(queue, sender, flags, iov, iovcnt, sent_cb);
+    return iov_size(iov, iovcnt);
+}
+
+static void filter_buffer_cleanup(NetFilterState *nf)
+{
+    FilterBufferState *s = DO_UPCAST(FilterBufferState, nf, nf);
+
+    if (s->interval) {
+        timer_del(&s->release_timer);
+    }
+
+    /* flush packets */
+    filter_buffer_flush(nf);
+    g_free(s->incoming_queue);
+    return;
+}
+
+static NetFilterInfo net_filter_buffer_info = {
+    .type = NET_FILTER_OPTIONS_KIND_BUFFER,
+    .size = sizeof(FilterBufferState),
+    .receive_iov = filter_buffer_receive_iov,
+    .cleanup = filter_buffer_cleanup,
+};
+
+int net_init_filter_buffer(const NetFilterOptions *opts, const char *name,
+                           int chain, NetClientState *netdev, Error **errp)
+{
+    NetFilterState *nf;
+    FilterBufferState *s;
+    const NetFilterBufferOptions *bufferopt;
+
+    assert(opts->kind == NET_FILTER_OPTIONS_KIND_BUFFER);
+    bufferopt = opts->buffer;
+
+    nf = qemu_new_net_filter(&net_filter_buffer_info, netdev, name, chain);
+    s = DO_UPCAST(FilterBufferState, nf, nf);
+    s->incoming_queue = qemu_new_net_queue(nf);
+    s->interval = bufferopt->has_interval ? bufferopt->interval : 0;
+    if (s->interval) {
+        timer_init_us(&s->release_timer, QEMU_CLOCK_VIRTUAL,
+                      filter_buffer_release_timer, s);
+        timer_mod(&s->release_timer,
+                  qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) + s->interval);
+    } else {
+        /*
+         * this check will be dropped when there're VM FT solutions like MC
+         * or COLO use this filter to release packets on demand.
+         */
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "interval",
+                   "a non-zero interval");
+        return -1;
+    }
+
+    return 0;
+}
diff --git a/net/filter.c b/net/filter.c
index 84245a7..9ed1b4a 100644
--- a/net/filter.c
+++ b/net/filter.c
@@ -19,6 +19,7 @@
 #include "net/filter.h"
 #include "net/net.h"
 #include "net/queue.h"
+#include "filters.h"
 
 static QTAILQ_HEAD(, NetFilterState) net_filters;
 
@@ -166,6 +167,7 @@ typedef int (NetFilterInit)(const NetFilterOptions *opts,
 
 static
 NetFilterInit * const net_filter_init_fun[NET_FILTER_OPTIONS_KIND_MAX] = {
+    [NET_FILTER_OPTIONS_KIND_BUFFER] = net_init_filter_buffer,
 };
 
 static int net_filter_init1(const NetFilter *netfilter, Error **errp)
diff --git a/net/filters.h b/net/filters.h
new file mode 100644
index 0000000..3b546db
--- /dev/null
+++ b/net/filters.h
@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2015 FUJITSU LIMITED
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_NET_FILTERS_H
+#define QEMU_NET_FILTERS_H
+
+#include "net/net.h"
+#include "net/filter.h"
+
+int net_init_filter_buffer(const NetFilterOptions *opts, const char *name,
+                           int chain, NetClientState *netdev, Error **errp);
+
+#endif /* QEMU_NET_FILTERS_H */
diff --git a/qapi-schema.json b/qapi-schema.json
index 9d97c21..7882641 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2584,6 +2584,21 @@
 { 'command': 'netfilter_del', 'data': {'id': 'str'} }
 
 ##
+# @NetFilterBufferOptions
+#
+# a netbuffer filter for network backend.
+#
+# @interval: #optional release packets by interval, if no interval supplied,
+#            will release packets when filter_buffer_release_all been called.
+#            scale: microsecond
+#
+# Since 2.5
+##
+{ 'struct': 'NetFilterBufferOptions',
+  'data': {
+    '*interval':     'uint32' } }
+
+##
 # @NetFilterOptions
 #
 # A discriminated record of network filters.
@@ -2592,7 +2607,8 @@
 #
 ##
 { 'union': 'NetFilterOptions',
-  'data': { } }
+  'data': {
+    'buffer':     'NetFilterBufferOptions'} }
 
 ##
 # @NetFilter
-- 
1.9.1