[Qemu-devel] [PATCH v2 4/5] net/dump: Add dump option for netdev devices

[Thomas Huth <thuth@redhat.com>]

So far it is not possible to dump network traffic with the "-netdev"
option yet - this is only possible with the "-net" option and an
internal "hub".
This patch now fixes this ugliness by adding a proper, generic
dumpfile parameter to the "-netdev" option.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 include/net/net.h |  1 +
 net/clients.h     |  2 ++
 net/dump.c        | 28 ++++++++++++++++++++++++++++
 net/net.c         | 38 +++++++++++++++++++++++++++++++++++++-
 qapi-schema.json  | 12 ++++++++++--
 5 files changed, 78 insertions(+), 3 deletions(-)

diff --git a/include/net/net.h b/include/net/net.h
index b265047..62abc98 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -98,6 +98,7 @@ struct NetClientState {
     NetClientDestructor *destructor;
     unsigned int queue_index;
     unsigned rxfilter_notify_enabled:1;
+    unsigned netdev_dump_enabled:1;
     NetDumpState nds;
 };
 
diff --git a/net/clients.h b/net/clients.h
index 403dc88..e120ed0 100644
--- a/net/clients.h
+++ b/net/clients.h
@@ -29,6 +29,8 @@
 
 int net_init_dump(const NetClientOptions *opts, const char *name,
                   NetClientState *peer, Error **errp);
+int netdev_init_dumpfile(const Netdev *netdev, const char *name,
+                                Error **errp);
 void net_dump_cleanup(NetClientState *nc);
 ssize_t net_dump_receive(NetClientState *nc, const uint8_t *buf, size_t size);
 ssize_t net_dump_receive_iov(NetClientState *nc, const struct iovec *iov,
diff --git a/net/dump.c b/net/dump.c
index fa63f0b..2cb3b4b 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -28,6 +28,7 @@
 #include "qemu/iov.h"
 #include "qemu/log.h"
 #include "qemu/timer.h"
+#include "net/vhost_net.h"
 #include "hub.h"
 
 #define PCAP_MAGIC 0xa1b2c3d4
@@ -197,3 +198,30 @@ int net_init_dump(const NetClientOptions *opts, const char *name,
     }
     return rc;
 }
+
+int netdev_init_dumpfile(const Netdev *netdev, const char *name,
+                                Error **errp)
+{
+    NetClientState *nc;
+    int dumplen = 65536;
+    int rc;
+
+    nc = qemu_find_netdev(name);
+    assert(nc);
+    if (get_vhost_net(nc)) {
+        error_setg(errp, "dumping does not work with vhost enabled");
+        return -1;
+    }
+
+    if (netdev->has_dumplen) {
+        dumplen = netdev->dumplen;
+    }
+
+    rc = net_dump_state_init(nc, netdev->dumpfile, dumplen, errp);
+    if (rc == 0) {
+        nc->netdev_dump_enabled = true;
+    }
+    /* TODO: Setup for multiqueue devices? */
+
+    return rc;
+}
diff --git a/net/net.c b/net/net.c
index 6ff7fec..1bdb731 100644
--- a/net/net.c
+++ b/net/net.c
@@ -360,6 +360,11 @@ static void qemu_cleanup_net_client(NetClientState *nc)
 {
     QTAILQ_REMOVE(&net_clients, nc, next);
 
+    if (nc->netdev_dump_enabled) {
+        net_dump_cleanup(nc);
+        nc->netdev_dump_enabled = 0;
+    }
+
     if (nc->info->cleanup) {
         nc->info->cleanup(nc);
     }
@@ -571,6 +576,21 @@ ssize_t qemu_deliver_packet(NetClientState *sender,
         return 0;
     }
 
+    /*
+     * Log network traffic into a dump file. Note: This should ideally
+     * be done after calling the ->receive() function below to make sure
+     * that we only log the packets that have really been sent. However,
+     * this does not work right with slirp networking since it immediately
+     * sends reply packets during the receive() function already, so we
+     * would get a wrong order of the packets in the dump file in that case.
+     */
+    if (sender->netdev_dump_enabled) {
+        net_dump_receive(sender, data, size);
+    }
+    if (nc->netdev_dump_enabled) {
+        net_dump_receive(nc, data, size);
+    }
+
     if (flags & QEMU_NET_PACKET_FLAG_RAW && nc->info->receive_raw) {
         ret = nc->info->receive_raw(nc, data, size);
     } else {
@@ -687,6 +707,13 @@ ssize_t qemu_deliver_packet_iov(NetClientState *sender,
         return 0;
     }
 
+    if (sender->netdev_dump_enabled) {
+        net_dump_receive_iov(sender, iov, iovcnt);
+    }
+    if (nc->netdev_dump_enabled) {
+        net_dump_receive_iov(nc, iov, iovcnt);
+    }
+
     if (nc->info->receive_iov) {
         ret = nc->info->receive_iov(nc, iov, iovcnt);
     } else {
@@ -880,7 +907,6 @@ static int net_init_nic(const NetClientOptions *opts, const char *name,
     return idx;
 }
 
-
 static int (* const net_client_init_fun[NET_CLIENT_OPTIONS_KIND_MAX])(
     const NetClientOptions *opts,
     const char *name,
@@ -966,6 +992,16 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
         }
         return -1;
     }
+
+    if (is_netdev) {
+        const Netdev *netdev = object;
+        if (netdev->has_dumpfile) {
+            if (netdev_init_dumpfile(netdev, name, errp)) {
+                return -1;
+            }
+        }
+    }
+
     return 0;
 }
 
diff --git a/qapi-schema.json b/qapi-schema.json
index 1285b8c..e7cd21f 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2531,14 +2531,22 @@
 #
 # @id: identifier for monitor commands.
 #
+# @dumpfile: #optional name of a file where network traffic should be logged
+#            (since: 2.5)
+#
+# @dumplen: #optional maximum length of the network packets in the dump
+#           (since: 2.5)
+#
 # @opts: device type specific properties
 #
 # Since 1.2
 ##
 { 'struct': 'Netdev',
   'data': {
-    'id':   'str',
-    'opts': 'NetClientOptions' } }
+    'id':        'str',
+    '*dumpfile': 'str',
+    '*dumplen':  'int32',
+    'opts':      'NetClientOptions' } }
 
 ##
 # @InetSocketAddress
-- 
1.8.3.1