From 30656b097e9dd7978d3fe9416cb9f5a421a9e63e Mon Sep 17 00:00:00 2001 From: Zhang Chen Date: Tue, 27 Sep 2016 10:22:34 +0800 Subject: 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 Signed-off-by: Li Zhijian Signed-off-by: Wen Congyang Signed-off-by: Jason Wang --- trace-events | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'trace-events') diff --git a/trace-events b/trace-events index b39536852e..1cb9d37ce4 100644 --- a/trace-events +++ b/trace-events @@ -150,6 +150,11 @@ colo_compare_ip_info(int psize, const char *sta, const char *stb, int ssize, con colo_old_packet_check_found(int64_t old_time) "%" PRId64 colo_compare_miscompare(void) "" +# net/filter-rewriter.c +colo_filter_rewriter_debug(void) "" +colo_filter_rewriter_pkt_info(const char *func, const char *src, const char *dst, uint32_t seq, uint32_t ack, uint32_t flag) "%s: src/dst: %s/%s p: seq/ack=%u/%u flags=%x\n" +colo_filter_rewriter_conn_offset(uint32_t offset) ": offset=%u\n" + ### Guest events, keep at bottom # @vaddr: Access' virtual address. -- cgit v1.2.3-55-g7522