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authorZhang Chen <zhangchen.fnst@cn.fujitsu.com>2016-09-27 10:22:34 +0800
committerJason Wang <jasowang@redhat.com>2016-09-27 17:54:22 +0800
commit30656b097e9dd7978d3fe9416cb9f5a421a9e63e (patch)
treec6b5ffa87a684d35686d77f436c5bde8b513dbbd /net/colo.h
parentafe461240940077e7ea8313e9c547a4898263cd2 (diff)
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>
Diffstat (limited to 'net/colo.h')
-rw-r--r--net/colo.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/net/colo.h b/net/colo.h
index 6720a3a8b7..7c524f3a1c 100644
--- a/net/colo.h
+++ b/net/colo.h
@@ -62,6 +62,13 @@ typedef struct Connection {
/* flag to enqueue unprocessed_connections */
bool processing;
uint8_t ip_proto;
+ /* offset = secondary_seq - primary_seq */
+ tcp_seq offset;
+ /*
+ * we use this flag update offset func
+ * run once in independent tcp connection
+ */
+ int syn_flag;
} Connection;
uint32_t connection_key_hash(const void *opaque);