tests/test-filter-redirector: Add unit test for filter-redirector

tests/test-filter-redirector: Add unit test for filter-redirector

In this unit test,we will test the filter redirector function.

Case 1, tx traffic flow:

qemu side              | test side
                       |
+---------+            |  +-------+
| backend <---------------+ sock0 |
+----+----+            |  +-------+
     |                 |
+----v----+  +-------+ |
|  rd0    +->+chardev| |
+---------+  +---+---+ |
                 |     |
+---------+      |     |
|  rd1    <------+     |
+----+----+            |
     |                 |
+----v----+            |  +-------+
|  rd2    +--------------->sock1  |
+---------+            |  +-------+
                       +

a. we(sock0) inject packet to qemu socket backend
b. backend pass packet to filter redirector0(rd0)
c. rd0 redirect packet to out_dev(chardev) which is connected with
filter redirector1's(rd1) in_dev
d. rd1 read this packet from in_dev, and pass to next filter redirector2(rd2)
e. rd2 redirect packet to rd2's out_dev which is connected with an opened socketed(sock1)
f. we read packet from sock1 and compare to what we inject

Start qemu with:

"-netdev socket,id=qtest-bn0,fd=%d "
"-device rtl8139,netdev=qtest-bn0,id=qtest-e0 "
"-chardev socket,id=redirector0,path=%s,server,nowait "
"-chardev socket,id=redirector1,path=%s,server,nowait "
"-chardev socket,id=redirector2,path=%s,nowait "
"-object filter-redirector,id=qtest-f0,netdev=qtest-bn0,"
"queue=tx,outdev=redirector0 "
"-object filter-redirector,id=qtest-f1,netdev=qtest-bn0,"
"queue=tx,indev=redirector2 "
"-object filter-redirector,id=qtest-f2,netdev=qtest-bn0,"
"queue=tx,outdev=redirector1 "

--------------------------------------
Case 2, rx traffic flow
qemu side              | test side
                       |
+---------+            |  +-------+
| backend +---------------> sock1 |
+----^----+            |  +-------+
     |                 |
+----+----+  +-------+ |
|  rd0    +<-+chardev| |
+---------+  +---+---+ |
                 ^     |
+---------+      |     |
|  rd1    +------+     |
+----^----+            |
     |                 |
+----+----+            |  +-------+
|  rd2    <---------------+sock0  |
+---------+            |  +-------+

a. we(sock0) insert packet to filter redirector2(rd2)
b. rd2 pass packet to filter redirector1(rd1)
c. rd1 redirect packet to out_dev(chardev) which is connected with
   filter redirector0's(rd0) in_dev
d. rd0 read this packet from in_dev, and pass ti to qemu backend which is
   connected with an opened socketed(sock1)
e. we read packet from sock1 and compare to what we inject

Start qemu with:

"-netdev socket,id=qtest-bn0,fd=%d "
"-device rtl8139,netdev=qtest-bn0,id=qtest-e0 "
"-chardev socket,id=redirector0,path=%s,server,nowait "
"-chardev socket,id=redirector1,path=%s,server,nowait "
"-chardev socket,id=redirector2,path=%s,nowait "
"-object filter-redirector,id=qtest-f0,netdev=qtest-bn0,"
"queue=rx,outdev=redirector0 "
"-object filter-redirector,id=qtest-f1,netdev=qtest-bn0,"
"queue=rx,indev=redirector2 "
"-object filter-redirector,id=qtest-f2,netdev=qtest-bn0,"
"queue=rx,outdev=redirector1 "

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>