[Spice-devel] [PATCH spice-server v2 2/2] stream-device: Create channels before first non-main channel connection

[Frediano Ziglio]

Due to ticket expiration, it is possible that the streaming channels for
the client are created after the ticket expires. Currently, streaming
channels are created dynamically when the guest starts streaming to the
server, which can happen at any time (for instance if you decide to start
the graphic server manually).
If the ticket has expired before the streaming channel is created,
authentication will fail and the client will not be able to connect.
To avoid this, create the channels when the first main channel connection
is made. This ensures that client will connect to all streaming channels.
This could be considered a temporary solution. There may be other
situations where it would be useful to connect new channels after the
ticket has expired, but enabling this behavior would require protocol
changes and a careful analysis of security implications.

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 server/reds-private.h  |  1 +
 server/reds.c          | 22 ++++++++++++++++++++++
 server/stream-device.c |  6 +++---
 server/stream-device.h |  1 +
 4 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/server/reds-private.h b/server/reds-private.h
index adc48ba5..920edc5c 100644
--- a/server/reds-private.h
+++ b/server/reds-private.h
@@ -117,6 +117,7 @@ struct RedsState {
     RedStatFile *stat_file;
 #endif
     int allow_multiple_clients;
+    bool late_initialization_done;
 
     /* Intermediate state for on going monitors config message from a single
      * client, being passed to the guest */
diff --git a/server/reds.c b/server/reds.c
index 9660476c..73c9ec20 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -1734,6 +1734,26 @@ static RedClient *reds_get_client(RedsState *reds)
     return reds->clients->data;
 }
 
+/* Performs late initializations steps.
+ * This should be called when a client connects */
+static void reds_late_initialization(RedsState *reds)
+{
+    RedCharDevice *dev;
+
+    // do only once
+    if (reds->late_initialization_done) {
+        return;
+    }
+
+    // create stream channels for streaming devices
+    GLIST_FOREACH(reds->char_devices, RedCharDevice, dev) {
+        if (IS_STREAM_DEVICE(dev)) {
+            stream_device_create_channel(STREAM_DEVICE(dev));
+        }
+    }
+    reds->late_initialization_done = true;
+}
+
 static void
 red_channel_capabilities_init_from_link_message(RedChannelCapabilities *caps,
                                                 const SpiceLinkMess *link_mess)
@@ -1769,6 +1789,8 @@ static void reds_handle_main_link(RedsState *reds, RedLinkInfo *link)
     spice_debug("trace");
     spice_assert(reds->main_channel);
 
+    reds_late_initialization(reds);
+
     link_mess = link->link_mess;
     if (!reds->allow_multiple_clients) {
         reds_disconnect(reds);
diff --git a/server/stream-device.c b/server/stream-device.c
index fd73e784..6cf29d37 100644
--- a/server/stream-device.c
+++ b/server/stream-device.c
@@ -538,8 +538,8 @@ stream_device_finalize(GObject *object)
     dev->msg_pos = 0;
 }
 
-static void
-allocate_channels(StreamDevice *dev)
+void
+stream_device_create_channel(StreamDevice *dev)
 {
     if (dev->stream_channel) {
         return;
@@ -600,7 +600,7 @@ stream_device_port_event(RedCharDevice *char_dev, uint8_t event)
     // reset device and channel on close/open
     dev->opened = (event == SPICE_PORT_EVENT_OPENED);
     if (dev->opened) {
-        allocate_channels(dev);
+        stream_device_create_channel(dev);
     }
     dev->hdr_pos = 0;
     dev->msg_pos = 0;
diff --git a/server/stream-device.h b/server/stream-device.h
index 501629c1..27efaeab 100644
--- a/server/stream-device.h
+++ b/server/stream-device.h
@@ -43,6 +43,7 @@ typedef struct StreamDeviceClass StreamDeviceClass;
 
 GType stream_device_get_type(void) G_GNUC_CONST;
 StreamDevice *stream_device_connect(RedsState *reds, SpiceCharDeviceInstance *sin);
+void stream_device_create_channel(StreamDevice *dev);
 
 G_END_DECLS
 
-- 
2.14.3