[Spice-devel] [PATCH spice-streaming-agent v3 2/2] Implement handling of error messages from the server

[Frediano Ziglio]

> 
> Signed-off-by: Lukáš Hrázký <lhrazky at redhat.com>
> ---
>  src/spice-streaming-agent.cpp | 28 +++++++++++++++++++++++++---
>  1 file changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
> index ee57920..53dbca0 100644
> --- a/src/spice-streaming-agent.cpp
> +++ b/src/spice-streaming-agent.cpp
> @@ -137,10 +137,32 @@ static void handle_stream_capabilities(uint32_t len)
>      }
>  }
>  
> -static void handle_stream_error(uint32_t len)
> +struct StreamMsgNotifyError1K : StreamMsgNotifyError {
> +    uint8_t msg[1024];
> +};
> +
> +static void handle_stream_error(size_t len)
>  {
> -    // TODO read message and use it
> -    throw std::runtime_error("got an error message from server");
> +    if (len < sizeof(StreamMsgNotifyError)) {
> +        throw std::runtime_error("Received NotifyError message size " +
> std::to_string(len) +
> +                                 " is too small (smaller than " +
> +
> std::to_string(sizeof(StreamMsgNotifyError))
> + ")");
> +    }
> +
> +    StreamMsgNotifyError1K msg;

I would have inlined the definition of the structure using
an unnamed structure but just question of style, fine for me.

> +
> +    size_t len_to_read = std::min(len, sizeof(msg));

buffer overflow, should be std::min(len, sizeof(msg)-1) to allow space for
terminator.

> +
> +    read_all(&msg, len_to_read);
> +    msg.msg[len_to_read - sizeof(StreamMsgNotifyError)] = '\0';
> +
> +    syslog(LOG_ERR, "Received NotifyError message from the server: %d -
> %s\n",
> +        msg.error_code, msg.msg);

Note that syslog don't need line termination (\n).

> +
> +    if (len_to_read > len) {

here should be if (len_to_read < len)

> +        throw std::runtime_error("Received NotifyError message size " +
> std::to_string(len) +
> +                                 " is too big (bigger than " +
> std::to_string(sizeof(msg)) + ")");
> +    }
>  }
>  
>  static void read_command_from_device(void)

Frediano