[Spice-devel] [PATCH spice] reds: Cancel unexpected xfer messages

[Frediano Ziglio]

> 
> Inform client that transfer will not work, instead of only
> dropping the agent messages.
> 
> The file transfer messages can be disabled using qemu cli option:
>  "disable-agent-file-xfer"
> 
> Resolves:
> https://bugzilla.redhat.com/show_bug.cgi?id=1373725
> 
> Signed-off-by: Pavel Grunt <pgrunt at redhat.com>
> ---
>  server/reds.c | 34 +++++++++++++++++++++++++++++++++-
>  1 file changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/server/reds.c b/server/reds.c
> index 3b30928a..ed4c2935 100644
> --- a/server/reds.c
> +++ b/server/reds.c
> @@ -1099,6 +1099,32 @@ static void
> reds_on_main_agent_monitors_config(RedsState *reds,
>      reds_client_monitors_config_cleanup(reds);
>  }
>  
> +static void agent_data_free(uint8_t *data, void *opaque G_GNUC_UNUSED)
> +{
> +    free(data);
> +}
> +
> +static void agent_xfer_error(MainChannelClient *mcc, const VDAgentMessage
> *message)
> +{
> +    VDAgentMessage *xfer_msg;
> +    VDAgentFileXferStatusMessage *xfer_status;
> +    size_t len = sizeof(VDAgentMessage) +
> sizeof(VDAgentFileXferStatusMessage);
> +
> +    g_return_if_fail(message->type >= VD_AGENT_FILE_XFER_START &&
> +                     message->type <= VD_AGENT_FILE_XFER_DATA);
> +
> +    xfer_msg = spice_malloc0(len);
> +    xfer_msg->protocol = VD_AGENT_PROTOCOL;
> +    xfer_msg->type = VD_AGENT_FILE_XFER_STATUS;
> +    xfer_msg->size = sizeof(VDAgentFileXferStatusMessage);
> +    xfer_status = (VDAgentFileXferStatusMessage *) xfer_msg->data;
> +    xfer_status->id = *((uint32_t *) message->data);

OT: works but defining a VDAgentFileXferCommonMessage with only the id would
be perhaps more readable.

> +    xfer_status->result = VD_AGENT_FILE_XFER_STATUS_ERROR;
> +
> +    spice_printerr("received xfer message on disabled file transfer, xfer id
> %u", xfer_status->id);

IMO too verbose, I'd avoid it.

> +    main_channel_client_push_agent_data(mcc, (uint8_t *) xfer_msg, len,
> agent_data_free, NULL);
> +}
> +
>  void reds_on_main_agent_data(RedsState *reds, MainChannelClient *mcc, void
>  *message, size_t size)
>  {
>      RedCharDeviceVDIPort *dev = reds->agent_dev;
> @@ -1110,8 +1136,14 @@ void reds_on_main_agent_data(RedsState *reds,
> MainChannelClient *mcc, void *mess
>      switch (res) {
>      case AGENT_MSG_FILTER_OK:
>          break;
> -    case AGENT_MSG_FILTER_DISCARD:
> +    case AGENT_MSG_FILTER_DISCARD: {
> +        const VDAgentMessage *agent_message = message;
> +        if (agent_message->type >= VD_AGENT_FILE_XFER_START &&
> +            agent_message->type <= VD_AGENT_FILE_XFER_DATA) {
> +            agent_xfer_error(mcc, agent_message);

I would move this logic into the separate function instead of checking
twice for message type (maybe changing function name).

> +        }
>          return;
> +    }
>      case AGENT_MSG_FILTER_MONITORS_CONFIG:
>          reds_on_main_agent_monitors_config(reds, mcc, message, size);
>          return;

Frediano