VNC: Cache client info at connection time

When a disconnection happens the client's socket on QEMU
side may become invalid, this way it won't be possible
to query it to get client information, which is going to
be needed by the future QMP VNC_DISCONNECTED event.

To always have this information available we query the
socket at connection time and cache the client info in
struct VncState.

Two function are introduced to perform this job.

vnc_client_cache_addr() is called right when the connection
is made, however the authentication information is not
available at that moment so vnc_client_cache_auth() is
called from protocol_client_init() to get auth info.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

2 files changed, 32 insertions, 10 deletions

diff --git a/vnc.c b/vnc.c
index e023824d3f..d37fa6021f 100644
--- a/vnc.c
+++ b/vnc.c
@@ -230,16 +230,16 @@ static int vnc_server_info_put(QDict *qdict)
     return 0;
 }
 
-static QDict *do_info_vnc_client(Monitor *mon, VncState *client)
+static void vnc_client_cache_auth(VncState *client)
 {
     QDict *qdict;
 
-    qdict = qdict_new();
-    if (vnc_qdict_remote_addr(qdict, client->csock) < 0) {
-        QDECREF(qdict);
-        return NULL;
+    if (!client->info) {
+        return;
     }
 
+    qdict = qobject_to_qdict(client->info);
+
 #ifdef CONFIG_VNC_TLS
     if (client->tls.session &&
         client->tls.dname) {
@@ -253,8 +253,20 @@ static QDict *do_info_vnc_client(Monitor *mon, VncState *client)
                   qstring_from_str(client->sasl.username));
     }
 #endif
+}
 
-    return qdict;
+static void vnc_client_cache_addr(VncState *client)
+{
+    QDict *qdict;
+
+    qdict = qdict_new();
+    if (vnc_qdict_remote_addr(qdict, client->csock) < 0) {
+        QDECREF(qdict);
+        /* XXX: how to report the error? */
+        return;
+    }
+
+    client->info = QOBJECT(qdict);
 }
 
 static void info_vnc_iter(QObject *obj, void *opaque)
@@ -339,16 +351,17 @@ void do_info_vnc(Monitor *mon, QObject **ret_data)
     if (vnc_display == NULL || vnc_display->display == NULL) {
         *ret_data = qobject_from_jsonf("{ 'enabled': false }");
     } else {
-        QDict *qdict;
         QList *clist;
 
         clist = qlist_new();
         if (vnc_display->clients) {
             VncState *client = vnc_display->clients;
             while (client) {
-                qdict = do_info_vnc_client(mon, client);
-                if (qdict)
-                    qlist_append(clist, qdict);
+                if (client->info) {
+                    /* incref so that it's not freed by upper layers */
+                    qobject_incref(client->info);
+                    qlist_append_obj(clist, client->info);
+                }
                 client = client->next;
             }
         }
@@ -1079,6 +1092,9 @@ static void vnc_disconnect_finish(VncState *vs)
         qemu_free(vs->output.buffer);
         vs->output.buffer = NULL;
     }
+
+    qobject_decref(vs->info);
+
 #ifdef CONFIG_VNC_TLS
     vnc_tls_client_cleanup(vs);
 #endif /* CONFIG_VNC_TLS */
@@ -2069,6 +2085,8 @@ static int protocol_client_init(VncState *vs, uint8_t *data, size_t len)
     vnc_write(vs, buf, size);
     vnc_flush(vs);
 
+    vnc_client_cache_auth(vs);
+
     vnc_read_when(vs, protocol_client_msg, 1);
 
     return 0;
@@ -2377,6 +2395,8 @@ static void vnc_connect(VncDisplay *vd, int csock)
     socket_set_nonblock(vs->csock);
     qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
 
+    vnc_client_cache_addr(vs);
+
     vs->vd = vd;
     vs->ds = vd->ds;
     vs->last_x = -1;
diff --git a/vnc.h b/vnc.h
index fcc6824127..1210824b18 100644
--- a/vnc.h
+++ b/vnc.h
@@ -144,6 +144,8 @@ struct VncState
     VncStateSASL sasl;
 #endif
 
+    QObject *info;
+
     Buffer output;
     Buffer input;
     /* current output mode information */