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Re: [Qemu-devel] [PATCH V11 8/9] filter-rewriter: track connection and p


From: Jason Wang
Subject: Re: [Qemu-devel] [PATCH V11 8/9] filter-rewriter: track connection and parse packet
Date: Tue, 2 Aug 2016 16:23:57 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0



On 2016年07月28日 18:12, Zhang Chen wrote:
We use colo-base.h to track connection and parse packet

Signed-off-by: Zhang Chen <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Wen Congyang <address@hidden>
---
  net/colo-base.c       | 14 ++++++++++++++
  net/colo-base.h       |  1 +
  net/filter-rewriter.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
  3 files changed, 65 insertions(+)

diff --git a/net/colo-base.c b/net/colo-base.c
index eb1b631..20797b5 100644
--- a/net/colo-base.c
+++ b/net/colo-base.c
@@ -103,6 +103,20 @@ void fill_connection_key(Packet *pkt, ConnectionKey *key)
      }
  }
+void reverse_connection_key(ConnectionKey *key)
+{
+    struct in_addr tmp_ip;
+    uint16_t tmp_port;
+
+    tmp_ip = key->src;
+    key->src = key->dst;
+    key->dst = tmp_ip;
+
+    tmp_port = key->src_port;
+    key->src_port = key->dst_port;
+    key->dst_port = tmp_port;
+}
+
  Connection *connection_new(ConnectionKey *key)
  {
      Connection *conn = g_slice_new(Connection);
diff --git a/net/colo-base.h b/net/colo-base.h
index 860a148..8d402a3 100644
--- a/net/colo-base.h
+++ b/net/colo-base.h
@@ -56,6 +56,7 @@ uint32_t connection_key_hash(const void *opaque);
  int connection_key_equal(const void *opaque1, const void *opaque2);
  int parse_packet_early(Packet *pkt);
  void fill_connection_key(Packet *pkt, ConnectionKey *key);
+void reverse_connection_key(ConnectionKey *key);
  Connection *connection_new(ConnectionKey *key);
  void connection_destroy(void *opaque);
  Connection *connection_get(GHashTable *connection_track_table,
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index 3a39f52..6350080 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -51,6 +51,20 @@ static void filter_rewriter_flush(NetFilterState *nf)
      }
  }
+/*
+ * Return 1 on success, if return 0 means the pkt
+ * is not TCP packet
+ */
+static int is_tcp_packet(Packet *pkt)
+{
+    if (!parse_packet_early(pkt) &&
+        pkt->ip->ip_p == IPPROTO_TCP) {
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
  static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
                                           NetClientState *sender,
                                           unsigned flags,
@@ -58,11 +72,47 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
                                           int iovcnt,
                                           NetPacketSent *sent_cb)
  {
+    RewriterState *s = FILTER_COLO_REWRITER(nf);
+    Connection *conn;
+    ConnectionKey key = {{ 0 } };
+    Packet *pkt;
+    ssize_t size = iov_size(iov, iovcnt);
+    char *buf = g_malloc0(size);
+
+    iov_to_buf(iov, iovcnt, 0, buf, size);
+    pkt = packet_new(buf, size);
+
      /*
       * if we get tcp packet
       * we will rewrite it to make secondary guest's
       * connection established successfully
       */
+    if (is_tcp_packet(pkt)) {
+
+        fill_connection_key(pkt, &key);
+
+        if (sender == nf->netdev) {
+            /*
+             * We need make tcp TX and RX packet
+             * into one connection.
+             */
+            reverse_connection_key(&key);

Why not simply do the comparing and swap in fill_connection_key()?

+        }
+        conn = connection_get(s->connection_track_table,
+                              &key,
+                              &s->hashtable_size);
+
+        if (sender == nf->netdev) {
+            /* NET_FILTER_DIRECTION_TX */
+            /* handle_primary_tcp_pkt */
+        } else {
+            /* NET_FILTER_DIRECTION_RX */
+            /* handle_secondary_tcp_pkt */
+        }
+    }
+
+    packet_destroy(pkt, NULL);
+    pkt = NULL;
      return 0;
  }




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