On Mon, Jun 4, 2018 at 1:51 PM, Jason Wang <jasow...@redhat.com> wrote:
>
>
> On 2018年06月03日 13:05, Zhang Chen wrote:
>
>> After a net connection is closed, we didn't clear its releated resources
>> in connection_track_table, which will lead to memory leak.
>>
>> Let't track the state of net connection, if it is closed, its related
>> resources will be cleared up.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
>> Signed-off-by: Zhang Chen <zhangc...@gmail.com>
>> ---
>> net/colo.h | 4 +++
>> net/filter-rewriter.c | 69 ++++++++++++++++++++++++++++++++++++++-----
>> 2 files changed, 66 insertions(+), 7 deletions(-)
>>
>> diff --git a/net/colo.h b/net/colo.h
>> index da6c36dcf7..cd118510c5 100644
>> --- a/net/colo.h
>> +++ b/net/colo.h
>> @@ -18,6 +18,7 @@
>> #include "slirp/slirp.h"
>> #include "qemu/jhash.h"
>> #include "qemu/timer.h"
>> +#include "slirp/tcp.h"
>> #define HASHTABLE_MAX_SIZE 16384
>> @@ -86,6 +87,9 @@ typedef struct Connection {
>> * run once in independent tcp connection
>> */
>> int syn_flag;
>> +
>> + int tcp_state; /* TCP FSM state */
>> + tcp_seq fin_ack_seq; /* the seq of 'fin=1,ack=1' */
>>
>
> So the question is, the state machine is not complete. I suspect there
> will be corner cases that will be left because of lacking sufficient
> states. LAST_ACK happens only for passive close. How about active close?
>
> So I think we need either maintain a full state machine or not instead of
> a partial one. We don't want endless bugs.
>
OK, I got it.
I will add a full state machine here in next version.
Thanks
Zhang Chen
>
> Thanks
>
>
> } Connection;
>> uint32_t connection_key_hash(const void *opaque);
>> diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
>> index 62dad2d773..0909a9a8af 100644
>> --- a/net/filter-rewriter.c
>> +++ b/net/filter-rewriter.c
>> @@ -59,9 +59,9 @@ static int is_tcp_packet(Packet *pkt)
>> }
>> /* handle tcp packet from primary guest */
>> -static int handle_primary_tcp_pkt(NetFilterState *nf,
>> +static int handle_primary_tcp_pkt(RewriterState *rf,
>> Connection *conn,
>> - Packet *pkt)
>> + Packet *pkt, ConnectionKey *key)
>> {
>> struct tcphdr *tcp_pkt;
>> @@ -99,15 +99,44 @@ static int handle_primary_tcp_pkt(NetFilterState
>> *nf,
>> net_checksum_calculate((uint8_t *)pkt->data +
>> pkt->vnet_hdr_len,
>> pkt->size - pkt->vnet_hdr_len);
>> }
>> + /*
>> + * Case 1:
>> + * The *server* side of this connect is VM, *client* tries to
>> close
>> + * the connection.
>> + *
>> + * We got 'ack=1' packets from client side, it acks 'fin=1,
>> ack=1'
>> + * packet from server side. From this point, we can ensure that
>> there
>> + * will be no packets in the connection, except that, some errors
>> + * happen between the path of 'filter object' and vNIC, if this
>> rare
>> + * case really happen, we can still create a new connection,
>> + * So it is safe to remove the connection from
>> connection_track_table.
>> + *
>> + */
>> + if ((conn->tcp_state == TCPS_LAST_ACK) &&
>> + (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
>> + g_hash_table_remove(rf->connection_track_table, key);
>> + }
>> + }
>> + /*
>> + * Case 2:
>> + * The *server* side of this connect is VM, *server* tries to close
>> + * the connection.
>> + *
>> + * We got 'fin=1, ack=1' packet from client side, we need to
>> + * record the seq of 'fin=1, ack=1' packet.
>> + */
>> + if ((tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
>> + conn->fin_ack_seq = htonl(tcp_pkt->th_seq);
>> + conn->tcp_state = TCPS_LAST_ACK;
>> }
>> return 0;
>> }
>> /* handle tcp packet from secondary guest */
>> -static int handle_secondary_tcp_pkt(NetFilterState *nf,
>> +static int handle_secondary_tcp_pkt(RewriterState *rf,
>> Connection *conn,
>> - Packet *pkt)
>> + Packet *pkt, ConnectionKey *key)
>> {
>> struct tcphdr *tcp_pkt;
>> @@ -139,8 +168,34 @@ static int handle_secondary_tcp_pkt(NetFilterState
>> *nf,
>> net_checksum_calculate((uint8_t *)pkt->data +
>> pkt->vnet_hdr_len,
>> pkt->size - pkt->vnet_hdr_len);
>> }
>> + /*
>> + * Case 2:
>> + * The *server* side of this connect is VM, *server* tries to
>> close
>> + * the connection.
>> + *
>> + * We got 'ack=1' packets from server side, it acks 'fin=1,
>> ack=1'
>> + * packet from client side. Like Case 1, there should be no
>> packets
>> + * in the connection from now know, But the difference here is
>> + * if the packet is lost, We will get the resent 'fin=1,ack=1'
>> packet.
>> + * TODO: Fix above case.
>> + */
>> + if ((conn->tcp_state == TCPS_LAST_ACK) &&
>> + (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
>> + g_hash_table_remove(rf->connection_track_table, key);
>> + }
>> + }
>> + /*
>> + * Case 1:
>> + * The *server* side of this connect is VM, *client* tries to close
>> + * the connection.
>> + *
>> + * We got 'fin=1, ack=1' packet from server side, we need to
>> + * record the seq of 'fin=1, ack=1' packet.
>> + */
>> + if ((tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
>> + conn->fin_ack_seq = ntohl(tcp_pkt->th_seq);
>> + conn->tcp_state = TCPS_LAST_ACK;
>> }
>> -
>> return 0;
>> }
>> @@ -190,7 +245,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState
>> *nf,
>> if (sender == nf->netdev) {
>> /* NET_FILTER_DIRECTION_TX */
>> - if (!handle_primary_tcp_pkt(nf, conn, pkt)) {
>> + if (!handle_primary_tcp_pkt(s, conn, pkt, &key)) {
>> qemu_net_queue_send(s->incoming_queue, sender, 0,
>> (const uint8_t *)pkt->data, pkt->size, NULL);
>> packet_destroy(pkt, NULL);
>> @@ -203,7 +258,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState
>> *nf,
>> }
>> } else {
>> /* NET_FILTER_DIRECTION_RX */
>> - if (!handle_secondary_tcp_pkt(nf, conn, pkt)) {
>> + if (!handle_secondary_tcp_pkt(s, conn, pkt, &key)) {
>> qemu_net_queue_send(s->incoming_queue, sender, 0,
>> (const uint8_t *)pkt->data, pkt->size, NULL);
>> packet_destroy(pkt, NULL);
>>
>
>
