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[Qemu-devel] [RFC PATCH V2 3/3] filter-rewriter: rewrite tcp packet to k
From: |
Zhang Chen |
Subject: |
[Qemu-devel] [RFC PATCH V2 3/3] filter-rewriter: rewrite tcp packet to keep secondary connection |
Date: |
Sat, 2 Jul 2016 14:22:20 +0800 |
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 <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Wen Congyang <address@hidden>
---
net/colo-base.h | 2 +
net/filter-rewriter.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++-
trace-events | 5 +++
3 files changed, 115 insertions(+), 2 deletions(-)
diff --git a/net/colo-base.h b/net/colo-base.h
index 62460c5..7b32648 100644
--- a/net/colo-base.h
+++ b/net/colo-base.h
@@ -71,6 +71,8 @@ typedef struct Connection {
uint8_t ip_proto;
/* be used by filter-rewriter */
colo_conn_state state;
+ /* offset = secondary_seq - primary_seq */
+ tcp_seq offset;
} Connection;
uint32_t connection_key_hash(const void *opaque);
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index c38ab24..9f63c75 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -21,6 +21,7 @@
#include "qemu/main-loop.h"
#include "qemu/iov.h"
#include "net/checksum.h"
+#include "trace.h"
#define FILTER_COLO_REWRITER(obj) \
OBJECT_CHECK(RewriterState, (obj), TYPE_FILTER_REWRITER)
@@ -64,6 +65,91 @@ static int is_tcp_packet(Packet *pkt)
}
}
+/* handle tcp packet from primary guest */
+static int handle_primary_tcp_pkt(NetFilterState *nf,
+ Connection *conn,
+ Packet *pkt)
+{
+ struct tcphdr *tcp_pkt;
+ static int syn_flag;
+
+ tcp_pkt = (struct tcphdr *)pkt->transport_layer;
+ if (trace_event_get_state(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
+ char *sdebug, *ddebug;
+ sdebug = strdup(inet_ntoa(pkt->ip->ip_src));
+ ddebug = strdup(inet_ntoa(pkt->ip->ip_dst));
+ trace_colo_filter_rewriter_pkt_info(__func__, sdebug, ddebug,
+ ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
+ tcp_pkt->th_flags);
+ trace_colo_filter_rewriter_conn_offset(conn->offset);
+ g_free(sdebug);
+ g_free(ddebug);
+ }
+
+ if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
+ /*
+ * this flag update offset func run oncs
+ * in independent tcp connection
+ */
+ syn_flag = 1;
+ }
+
+ if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
+ if (syn_flag) {
+ /* offset = secondary_seq - primary seq */
+ conn->offset -= (ntohl(tcp_pkt->th_ack));
+ syn_flag = 0;
+
+ }
+ /* handle packets to the secondary from the primary */
+ tcp_pkt->th_ack = htonl(ntohl(tcp_pkt->th_ack) + conn->offset + 1);
+
+ net_checksum_calculate((uint8_t *)pkt->data, pkt->size);
+ }
+
+ return 0;
+}
+
+/* handle tcp packet from secondary guest */
+static int handle_secondary_tcp_pkt(NetFilterState *nf,
+ Connection *conn,
+ Packet *pkt)
+{
+ struct tcphdr *tcp_pkt;
+
+ tcp_pkt = (struct tcphdr *)pkt->transport_layer;
+
+ if (trace_event_get_state(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
+ char *sdebug, *ddebug;
+ sdebug = strdup(inet_ntoa(pkt->ip->ip_src));
+ ddebug = strdup(inet_ntoa(pkt->ip->ip_dst));
+ trace_colo_filter_rewriter_pkt_info(__func__, sdebug, ddebug,
+ ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
+ tcp_pkt->th_flags);
+ trace_colo_filter_rewriter_conn_offset(conn->offset);
+ g_free(sdebug);
+ g_free(ddebug);
+ }
+
+ if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
+ /*
+ * save offset = secondary_seq and then
+ * in handle_primary_tcp_pkt make offset
+ * = secondary_seq - primary_seq
+ */
+ conn->offset = ntohl(tcp_pkt->th_seq);
+ }
+
+ if ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK) {
+ /* handle packets to the primary from the secondary*/
+ tcp_pkt->th_seq = htonl(ntohl(tcp_pkt->th_seq) - conn->offset - 1);
+
+ net_checksum_calculate((uint8_t *)pkt->data, pkt->size);
+ }
+
+ return 0;
+}
+
static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
NetClientState *sender,
unsigned flags,
@@ -105,10 +191,30 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState
*nf,
if (sender == nf->netdev) {
/* NET_FILTER_DIRECTION_TX */
- /* handle_primary_tcp_pkt */
+ if (!handle_primary_tcp_pkt(nf, conn, pkt)) {
+ qemu_net_queue_send(s->incoming_queue, sender, 0,
+ (const uint8_t *)pkt->data, pkt->size, NULL);
+ packet_destroy(pkt, NULL);
+ pkt = NULL;
+ /*
+ * We block the packet here,after rewrite pkt
+ * and will send it
+ */
+ return 1;
+ }
} else {
/* NET_FILTER_DIRECTION_RX */
- /* handle_secondary_tcp_pkt */
+ if (!handle_secondary_tcp_pkt(nf, conn, pkt)) {
+ qemu_net_queue_send(s->incoming_queue, sender, 0,
+ (const uint8_t *)pkt->data, pkt->size, NULL);
+ packet_destroy(pkt, NULL);
+ pkt = NULL;
+ /*
+ * We block the packet here,after rewrite pkt
+ * and will send it
+ */
+ return 1;
+ }
}
}
diff --git a/trace-events b/trace-events
index 6686cdf..5ac56f6 100644
--- a/trace-events
+++ b/trace-events
@@ -1927,3 +1927,8 @@ colo_compare_icmp_miscompare_mtu(const char *sta, int
size) ": %s %d"
colo_compare_ip_info(int psize, const char *sta, const char *stb, int ssize,
const char *stc, const char *std) "ppkt size = %d, ip_src = %s, ip_dst = %s,
spkt size = %d, ip_src = %s, ip_dst = %s"
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"
--
2.7.4
[Qemu-devel] [RFC PATCH V2 3/3] filter-rewriter: rewrite tcp packet to keep secondary connection,
Zhang Chen <=