Commit Graph

6 Commits

Author SHA1 Message Date
Zhang Chen 30656b097e filter-rewriter: rewrite tcp packet to keep secondary connection
We will rewrite tcp packet secondary received and sent.
When colo guest is a tcp server.

Firstly, client start a tcp handshake. the packet's seq=client_seq,
ack=0,flag=SYN. COLO primary guest get this pkt and mirror(filter-mirror)
to secondary guest, secondary get it use filter-redirector.
Then,primary guest response pkt
(seq=primary_seq,ack=client_seq+1,flag=ACK|SYN).
secondary guest response pkt
(seq=secondary_seq,ack=client_seq+1,flag=ACK|SYN).
In here,we use filter-rewriter save the secondary_seq to it's tcp connection.
Finally handshake,client send pkt
(seq=client_seq+1,ack=primary_seq+1,flag=ACK).
Here,filter-rewriter can get primary_seq, and rewrite ack from primary_seq+1
to secondary_seq+1, recalculate checksum. So the secondary tcp connection
kept good.

When we send/recv packet.
client send pkt(seq=client_seq+1+data_len,ack=primary_seq+1,flag=ACK|PSH).
filter-rewriter rewrite ack and send to secondary guest.

primary guest response pkt
(seq=primary_seq+1,ack=client_seq+1+data_len,flag=ACK)
secondary guest response pkt
(seq=secondary_seq+1,ack=client_seq+1+data_len,flag=ACK)
we rewrite secondary guest seq from secondary_seq+1 to primary_seq+1.
So tcp connection kept good.

In code We use offset( = secondary_seq - primary_seq )
to rewrite seq or ack.
handle_primary_tcp_pkt: tcp_pkt->th_ack += offset;
handle_secondary_tcp_pkt: tcp_pkt->th_seq -= offset;

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2016-09-27 17:54:22 +08:00
Zhang Chen afe4612409 filter-rewriter: track connection and parse packet
We use net/colo.h to track connection and parse packet

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2016-09-27 17:54:22 +08:00
Zhang Chen 0682e15b19 colo-compare: introduce packet comparison thread
If primary packet is same with secondary packet,
we will send primary packet and drop secondary
packet, otherwise notify COLO frame to do checkpoint.
If primary packet comes but secondary packet does not,
after REGULAR_PACKET_CHECK_MS milliseconds we set
the primary packet as old_packet,then do a checkpoint.

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2016-09-27 17:54:22 +08:00
Zhang Chen b6540d403d colo-compare: track connection and enqueue packet
In this patch we use kernel jhash table to track
connection, and then enqueue net packet like this:

+ CompareState ++
|               |
+---------------+   +---------------+         +---------------+
|conn list      +--->conn           +--------->conn           |
+---------------+   +---------------+         +---------------+
|               |     |           |             |          |
+---------------+ +---v----+  +---v----+    +---v----+ +---v----+
                  |primary |  |secondary    |primary | |secondary
                  |packet  |  |packet  +    |packet  | |packet  +
                  +--------+  +--------+    +--------+ +--------+
                      |           |             |          |
                  +---v----+  +---v----+    +---v----+ +---v----+
                  |primary |  |secondary    |primary | |secondary
                  |packet  |  |packet  +    |packet  | |packet  +
                  +--------+  +--------+    +--------+ +--------+
                      |           |             |          |
                  +---v----+  +---v----+    +---v----+ +---v----+
                  |primary |  |secondary    |primary | |secondary
                  |packet  |  |packet  +    |packet  | |packet  +
                  +--------+  +--------+    +--------+ +--------+

We use conn_list to record connection info.
When we want to enqueue a packet, firstly get the
connection from connection_track_table. then push
the packet to g_queue(pri/sec) in it's own conn.

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2016-09-27 17:54:21 +08:00
Zhang Chen ccf0426c09 Jhash: add linux kernel jhashtable in qemu
Jhash will be used by colo-compare and filter-rewriter
to save and lookup net connection info

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2016-09-27 17:54:21 +08:00
Zhang Chen 59509ec16b net/colo.c: add colo.c to define and handle packet
The net/colo.c is used by colo-compare and filter-rewriter.
this can share common data structure like net packet,
and other functions.

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2016-09-27 17:54:21 +08:00