[ENet-discuss] possible enet bug #2

[Lee Salzman]

This appears to have the potential for happening in theory, yes. You
would have to be making multiple calls  to enet_peer_disconnect and
under some very odd circumstances for it to occur, since the resend
mechanism will never duplicate a command within an individual packet.
However, under actual use I don't think I've ever seen it occur.

Anyway, I committed a small fix to the CVS tree for this.

Lee

eye at dihalt.com wrote:
> Hello, it's me again.
>
> It seems that if enet encounters two or more
> ENET_PROTOCOL_COMMAND_DISCONNECT packets it will NOT send
> back acknowledgement to a peer and will NOT generate
> ENET_EVENT_TYPE_DISCONNECT event. This may happen due to a
> network lang and was sucesfully recreated in my test
> environment.
>
> possible cause:
>
> network data is received inside
> enet_protocol_receive_incoming_commands() until either
> enet_protocol_handle_incoming_commands() marks a packet as
> processed or no more network data available.
> ENET_PROTOCOL_COMMAND_DISCONNECT is processed inside
> enet_protocol_handle_disconnect() function that is state
> based. If we have 2 DISCONNECT commands, first call to
> enet_protocol_handle_disconnect() will set peer state to
> ENET_PEER_STATE_ACKNOWLEDGING_DISCONNECT. But packet will
> not be marked as
> processed and enet_protocol_receive_incoming_commands()
> will continue to process network data! And than second
> DISCONNECT command is encountered, 
> enet_protocol_handle_disconnect() will call
> enet_peer_reset() - no acknowledgement will be sent and no
> disconnect event will be generated.
>
> possible fix:
>
> additional state check inside
> enet_protocol_handle_disconnect(), like this:
>
> else if( ENET_PEER_STATE_ACKNOWLEDGING_DISCONNECT ==
> peer->state )
> {
>   return true; // second disconnect while previous not
> processed
> }
>
> What can you say? Is it worth to be fixed or i'm doing
> something wrong again? Bug was sucesfully recreated on my
> test computers while sending huge amouns of data with
> different packet sizes and netwok bandwidths. Happens ~
> once a hour, it's not very common for two or more
> disconnect packets to be on server side due to a lag :).
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>