net: always walk through filters in reverse if traffic is egress

Previously, if we attach more than one filters for a single netdev,
both ingress and egress traffic will go through net filters in same
order like:

ingress: netdev ->filter1 ->filter2 ->...filter[n] ->emulated device
egress: emulated device ->filter1 ->filter2 ->...filter[n] ->netdev.

This is against the natural feeling and will complicate filters
configuration since in some scenes, we hope filters handle the egress
traffic in a reverse order. For example, in colo-proxy (will be
implemented later), we have a redirector filter and a colo-rewriter
filter, we need the filter behave like:

ingress(->)/egress(<-): chardev<->redirector<->colo-rewriter<->emulated device

Since both buffer filter and dump do not require strict order of
filters, this patch switches to always let egress traffic walk through
net filters in reverse to simplify the possible filters configuration
in the future.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Yang Hongyang <hongyang.yang@easystack.cn>
Signed-off-by: Jason Wang <jasowang@redhat.com>

diff --git a/include/net/net.h b/include/net/net.h
index 7af3e15f83bfefe52ea95fe8129af0563d1c400a..73e4c466e2fa409abfd9228c68022b0aaff1fcf9 100644 (file)
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -92,7 +92,7 @@ struct NetClientState {
     NetClientDestructor *destructor;
     unsigned int queue_index;
     unsigned rxfilter_notify_enabled:1;
-    QTAILQ_HEAD(, NetFilterState) filters;
+    QTAILQ_HEAD(NetFilterHead, NetFilterState) filters;
 };
 
 typedef struct NICState {

diff --git a/net/filter.c b/net/filter.c
index 5d90f83429fdb8ac539910abcf32831f50a5a8a2..17a83982b9b50258d2e0f8f2008c8874af5fdac4 100644 (file)
--- a/net/filter.c
+++ b/net/filter.c
@@ -34,6 +34,22 @@ ssize_t qemu_netfilter_receive(NetFilterState *nf,
     return 0;
 }
 
+static NetFilterState *netfilter_next(NetFilterState *nf,
+                                      NetFilterDirection dir)
+{
+    NetFilterState *next;
+
+    if (dir == NET_FILTER_DIRECTION_TX) {
+        /* forward walk through filters */
+        next = QTAILQ_NEXT(nf, next);
+    } else {
+        /* reverse order */
+        next = QTAILQ_PREV(nf, NetFilterHead, next);
+    }
+
+    return next;
+}
+
 ssize_t qemu_netfilter_pass_to_next(NetClientState *sender,
                                     unsigned flags,
                                     const struct iovec *iov,
@@ -43,7 +59,7 @@ ssize_t qemu_netfilter_pass_to_next(NetClientState *sender,
     int ret = 0;
     int direction;
     NetFilterState *nf = opaque;
-    NetFilterState *next = QTAILQ_NEXT(nf, next);
+    NetFilterState *next = NULL;
 
     if (!sender || !sender->peer) {
         /* no receiver, or sender been deleted, no need to pass it further */
@@ -61,6 +77,7 @@ ssize_t qemu_netfilter_pass_to_next(NetClientState *sender,
         direction = nf->direction;
     }
 
+    next = netfilter_next(nf, direction);
     while (next) {
         /*
          * if qemu_netfilter_pass_to_next been called, means that
@@ -73,7 +90,7 @@ ssize_t qemu_netfilter_pass_to_next(NetClientState *sender,
         if (ret) {
             return ret;
         }
-        next = QTAILQ_NEXT(next, next);
+        next = netfilter_next(next, direction);
     }
 
     /*

diff --git a/net/net.c b/net/net.c
index 87dd3568dc2d8bf2766462d1386eceb86d457ec3..c929c41a109d47e552833f244b83cbd909b423f7 100644 (file)
--- a/net/net.c
+++ b/net/net.c
@@ -580,11 +580,21 @@ static ssize_t filter_receive_iov(NetClientState *nc,
     ssize_t ret = 0;
     NetFilterState *nf = NULL;
 
-    QTAILQ_FOREACH(nf, &nc->filters, next) {
-        ret = qemu_netfilter_receive(nf, direction, sender, flags, iov,
-                                     iovcnt, sent_cb);
-        if (ret) {
-            return ret;
+    if (direction == NET_FILTER_DIRECTION_TX) {
+        QTAILQ_FOREACH(nf, &nc->filters, next) {
+            ret = qemu_netfilter_receive(nf, direction, sender, flags, iov,
+                                         iovcnt, sent_cb);
+            if (ret) {
+                return ret;
+            }
+        }
+    } else {
+        QTAILQ_FOREACH_REVERSE(nf, &nc->filters, NetFilterHead, next) {
+            ret = qemu_netfilter_receive(nf, direction, sender, flags, iov,
+                                         iovcnt, sent_cb);
+            if (ret) {
+                return ret;
+            }
         }
     }