[ENet-discuss] NAT hole punching with Enet - query on an approach

[Madhan Kanagavel]

Here's how it would look like, in protocol.c

=================================================================

static int
enet_protocol_receive_incoming_commands (ENetHost * host, ENetEvent * event)
{
    for (;;)
    {
       int receivedLength;
       ENetBuffer buffer;

       buffer.data = host -> receivedData;
       buffer.dataLength = sizeof (host -> receivedData);

       receivedLength = enet_socket_receive (host -> socket,
                                             & host -> receivedAddress,
                                             & buffer,
                                             1);

       if (receivedLength < 0)
         return -1;

       if (receivedLength == 0)
         return 0;

       host -> receivedDataLength = receivedLength;

       // ... ------------------> Modify
       if (ProcessPacket(host))
            return 0;
       // ...-----------------> Modify
       

=================================================================

Then in ProcessPacket, we check the start of the packet

int ProcessPacket(ENetHost * host)
{
    uint32_bt flag;
    memcpy(&flag, host->receivedData, sizeof(uint32_bt));
    if (flag == 0xFAAAFAAA) // check for some special values
    {
     // ... our packet.. do more work
         return 1;
    }
   // ... enet packet
   return 0;
}


----- Original Message ----
From: Daniel Aquino <mr.danielaquino at gmail.com>
To: Madhan Kanagavel <madhan at yahoo.com>; Discussion of the ENet library <enet-discuss at cubik.org>
Sent: Saturday, May 16, 2009 5:43:44 PM
Subject: Re: [ENet-discuss] NAT hole punching with Enet - query on an approach

Do you think you can provide your modifications to enet that show how
your reading your own data and then passing it off to enet ?

On Mon, Apr 27, 2009 at 7:48 PM, Madhan Kanagavel <madhan at yahoo.com> wrote:
>
> That is how we do it in Tonido (www.tonido.com) for NAT traversal.
>
> We have our own layer that does NAT punch so that ENet can establish connection. It uses the same UDP socket.
> We simply look at each packet(first couple of bytes) before handing it over to ENet. It works pretty well.
>
> By the way, much thanks to ENet. Its a great library, considering how much we have abused it. :-)
> It has withstood everything amazingly well.
>
> -Madhan
>
>
>
>
> ----- Original Message ----
> From: Daniel Aquino <mr.danielaquino at gmail.com>
> To: Discussion of the ENet library <enet-discuss at cubik.org>
> Sent: Monday, April 27, 2009 4:41:25 PM
> Subject: Re: [ENet-discuss] NAT hole punching with Enet - query on an approach
>
> Are you saying that I could send/recieve my own type of data on the
> udp port even while enet is using it ?
>
> On Mon, Apr 27, 2009 at 11:38 PM, Lee Salzman <lsalzman1 at cox.net> wrote:
>> Almost anything that doesn't look ike a valid ENet packet will be ignored.
>>
>> Lee
>>
>> M. Rijks wrote:
>>>
>>> Thank you for your reaction Shawn.
>>>
>>> Yes, I considered sending around UDP packets before getting ENet in the
>>> equation. However, I have a timing issue there. After the game server has
>>> punched through towards the client IP+port, I need to find an appropriate
>>> time for the client to initiate the ENet connection on the other end. But I
>>> don't exactly know if, or when, the server's punch packet arrives at the
>>> client. I can't wait for its arrival since the client's firewall may block
>>> it entirely. So there is the risk that when I finally tell the client to
>>> initiate its connection to the server, it first receives the UDP packet that
>>> was used to merely punch the server-end hole. It will most likely contain
>>> data that will make no sense to the client, throwing off ENet's connection
>>> protocol.
>>>
>>> Maybe I should change my question into "what kind of UDP packet content
>>> will ENet happily ignore when waiting for the connection to establish?" :)
>>>
>>> Cheers,
>>>
>>> Martin
>>>
>>
>> _______________________________________________
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>> ENet-discuss at cubik.org
>> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>
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