[ENet-discuss] Connecting to self (resolved)
Lee Salzman
lsalzman at gmail.com
Tue Nov 12 02:45:42 PST 2013
That's more or less the check I had in mind. In theory the peer bookkeeping
should work fine. But that's theory. It is the practice that must be
verified. :)
On Tue, Nov 12, 2013 at 12:31 PM, Krasimir Marinov <krasi at jklsemi.com>wrote:
> Thanks Lee!
>
> That sheds some light on this check. I've applied this patch in order to
> allow loopback connects:
>
>
> --- enet-1.3.9/protocol.c 2013-08-18 17:16:04.000000000 +0300
>
> +++ enet-1.3.9.mod/protocol.c 2013-11-12 12:21:18.000000000 +0200
>
> @@ -299,7 +299,10 @@
>
> else
>
> if (currentPeer -> address.host == host -> receivedAddress.host)
>
> {
>
> - if (currentPeer -> address.port == host ->
> receivedAddress.port &&
>
> + /* This check prevents duplicate *connection attempts*
> resulting
>
> + from a connection packet being retransmitted */
>
> + if (currentPeer -> state != ENET_PEER_STATE_CONNECTING &&
>
> + currentPeer -> address.port == host ->
> receivedAddress.port &&
>
> currentPeer -> connectID == command -> connect.connectID)
>
> return NULL;
>
>
>
> Is this the (ENET_PEER_STATE_CONNECTING) check you mentioned?
>
> As for the throttling, based on my shallow view of the current
> implementation, I thought it won't be messed, because the
> throttling-related bookkeeping is *per peer*, so it won't matter where the
> peer comes from (localhost, another host, or the loopback connect). Am I
> right?
>
>
>
> On Tue, Nov 12, 2013 at 11:27 AM, Lee Salzman <lsalzman at gmail.com> wrote:
>
>> Sorry for the late response, as I was away for the weekend. After looking
>> into it, that check ultimately prevents duplicate *connection attempts*
>> resulting from a connection packet being retransmitted. There is a quite
>> easy work-around for it in theory, by just adding a check for the
>> ENET_PEER_STATE_CONNECTING state (which indicates the sender of the connect
>> attempt) and skipping it if it is found. What I don't know is if or how
>> this will mess up the peer management for things like throttling when there
>> are two peers on a single host representing both ends of a single
>> connection, if said loopback connections where host and client are the same
>> are allowed to proceed.
>>
>> An enterprising person would have to experiment and verify everything
>> works fine, but I myself won't have time to futz with this till the weekend
>> at best.
>>
>>
>> On Fri, Nov 8, 2013 at 9:45 PM, Erwin Coumans <erwin.coumans at gmail.com>wrote:
>>
>>>
>>> I suppose Krasimir wants to use a single ENetHosts
>>> for server and client for this reason:
>>>
>>> "If I switch to two separate ENetHosts then I can connect to myself
>>> fine, but I suspect that this is going to subtly upset the
>>> auto-throttling (i.e. each ENetHost will try to throttle around
>>> spikes caused by the other, since they don't share accounting)."
>>>
>>> See
>>> http://lists.cubik.org/pipermail/enet-discuss/2004-December/000313.html
>>>
>>>
>>>
>>> On 8 November 2013 10:00, Ruud van Gaal <ruud at racer.nl> wrote:
>>>
>>>> Ah ok, but the concept behind Client & Server is that you have 2 hosts,
>>>> right? A client host and a server host...
>>>> Ruud
>>>>
>>>>
>>>> On Fri, Nov 8, 2013 at 6:10 PM, Krasimir Marinov <krasi at jklsemi.com>wrote:
>>>>
>>>>> You won't hit this case unless you use *only one* ENetHost. If your
>>>>> client and server are separate ENetHost(s) then there is no "loopback"
>>>>> connect.
>>>>>
>>>>>
>>>>> On Fri, Nov 8, 2013 at 7:02 PM, Ruud van Gaal <ruud at racer.nl> wrote:
>>>>>
>>>>>> That is strange, the check and refusal of that connection.
>>>>>> One thing that might be different from my case is that I obtain the
>>>>>> IP address of the localhost. So I setup a server at 192.168.0.10 for
>>>>>> example, rather than 127.0.0.1.
>>>>>> The connecting client then may or may not connect to 127.0.0.1 or
>>>>>> 192.168.0.10.
>>>>>> It might be interesting to see what the 4 variants do: 192.168.0.10
>>>>>> connecting to 127.0.0.1 and its four variants (192/192, 192/127, 127/127,
>>>>>> 127/192).
>>>>>>
>>>>>> Hm,
>>>>>> Ruud
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Fri, Nov 8, 2013 at 5:16 PM, Krasimir Marinov <krasi at jklsemi.com>wrote:
>>>>>>
>>>>>>> I decided to dig a bit deeper into this "issue" and here are my
>>>>>>> findings:
>>>>>>>
>>>>>>> There is a special section in
>>>>>>> protocol.c/enet_protocol_handle_connect()/row 302 that prevents from
>>>>>>> connecting to our own host (loopback connect):
>>>>>>>
>>>>>>> 302 if (currentPeer -> address.port == host ->
>>>>>>> receivedAddress.port &&
>>>>>>>
>>>>>>> 303 currentPeer -> connectID == command -> connect.connectID)
>>>>>>> {
>>>>>>>
>>>>>>> 304 printf("enet_protocol_handle_connect(): loopback
>>>>>>> connect = return NULL\n");
>>>>>>>
>>>>>>> 305 //return NULL;
>>>>>>>
>>>>>>>
>>>>>>> 306 }
>>>>>>> I've modified it with a printf() statement to debug.
>>>>>>>
>>>>>>> With the following test program when using the original version I'm
>>>>>>> unable to connect to myself. With the modified ENet version I get two
>>>>>>> connect events - one for the peer initiating connect and one for the peer
>>>>>>> being connected.
>>>>>>>
>>>>>>> This is the output:
>>>>>>>
>>>>>>> Connecting peer 0x7fed91006000
>>>>>>>
>>>>>>> enet_protocol_handle_connect(): loopback connect = return NULL
>>>>>>>
>>>>>>> A new peer (0x7fed91006000) connected from 100007f:55555.
>>>>>>>
>>>>>>> A new peer (0x7fed910061d0) connected from 100007f:55555.
>>>>>>>
>>>>>>> And here is the program:
>>>>>>>
>>>>>>> #include <enet/enet.h>
>>>>>>>
>>>>>>> #include <stdio.h>
>>>>>>>
>>>>>>>
>>>>>>> int main() {
>>>>>>>
>>>>>>> ENetAddress address;
>>>>>>>
>>>>>>> ENetHost *host;
>>>>>>>
>>>>>>> ENetPeer *peer;
>>>>>>>
>>>>>>> ENetEvent event;
>>>>>>>
>>>>>>>
>>>>>>> enet_address_set_host(&address, "127.0.0.1");
>>>>>>>
>>>>>>> address.port = 55555;
>>>>>>>
>>>>>>>
>>>>>>> host = enet_host_create (&address, 32, 1, 0, 0);
>>>>>>>
>>>>>>> peer = enet_host_connect(host, &address, 1, 0);
>>>>>>>
>>>>>>>
>>>>>>> printf("Connecting peer %p\n", peer);
>>>>>>>
>>>>>>>
>>>>>>> while (enet_host_service (host, & event, 100000) > 0) {
>>>>>>>
>>>>>>> switch (event.type) {
>>>>>>>
>>>>>>> case ENET_EVENT_TYPE_CONNECT:
>>>>>>>
>>>>>>> printf ("A new peer (%p) connected from %x:%u.\n",
>>>>>>>
>>>>>>> event.peer,
>>>>>>>
>>>>>>> event.peer -> address.host,
>>>>>>>
>>>>>>> event.peer -> address.port);
>>>>>>>
>>>>>>> /* Store any relevant client information here. */
>>>>>>>
>>>>>>> event.peer -> data = "Client information";
>>>>>>>
>>>>>>> break;
>>>>>>>
>>>>>>> case ENET_EVENT_TYPE_RECEIVE:
>>>>>>>
>>>>>>> printf ("A packet of length %lu containing %s was received
>>>>>>> from %s on channel %u.\n",
>>>>>>>
>>>>>>> event.packet -> dataLength,
>>>>>>>
>>>>>>> event.packet -> data,
>>>>>>>
>>>>>>> event.peer -> data,
>>>>>>>
>>>>>>> event.channelID);
>>>>>>>
>>>>>>> /* Clean up the packet now that we're done using it. */
>>>>>>>
>>>>>>> enet_packet_destroy (event.packet);
>>>>>>>
>>>>>>> break;
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> case ENET_EVENT_TYPE_DISCONNECT:
>>>>>>>
>>>>>>> if(event.peer->data)
>>>>>>>
>>>>>>> printf ("%p: %s disconected.\n", event.peer, event.peer ->
>>>>>>> data);
>>>>>>>
>>>>>>> else
>>>>>>>
>>>>>>> printf("%p: disconnected\n", event.peer);
>>>>>>>
>>>>>>> /* Reset the peer's client information. */
>>>>>>>
>>>>>>> event.peer -> data = NULL;
>>>>>>>
>>>>>>> break;
>>>>>>>
>>>>>>> default:
>>>>>>>
>>>>>>> printf("default\n");
>>>>>>>
>>>>>>> break;
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Regards,
>>>>>>> Krasimir
>>>>>>>
>>>>>>> On Thu, Nov 7, 2013 at 12:45 PM, Krasimir Marinov <krasi at jklsemi.com
>>>>>>> > wrote:
>>>>>>>
>>>>>>>> The code that you shared connects peers from 2 different ENetHosts.
>>>>>>>>
>>>>>>>> The pseudocode that I showed
>>>>>>>>
>>>>>>>> ENetAddress address;
>>>>>>>> a.host = <localhost>
>>>>>>>> a.port = <port>
>>>>>>>>
>>>>>>>> EnetHost *host = enet_host_create(&address, .....);
>>>>>>>> enet_host_connect(host, &address, ...);
>>>>>>>>
>>>>>>>> tries to connect the host to itself. Notice that there is only one
>>>>>>>> address and one host!
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Thu, Nov 7, 2013 at 12:08 PM, Andrew Fenn <andrewfenn at gmail.com>wrote:
>>>>>>>>
>>>>>>>>> I don't have any problems with a running a client / server on the
>>>>>>>>> same
>>>>>>>>> machine. My code is available here, it's unfinished overall however
>>>>>>>>> the enet connection stuff has worked without problems for a long
>>>>>>>>> time.
>>>>>>>>>
>>>>>>>>> https://github.com/andrewfenn/Hardwar
>>>>>>>>> Server:
>>>>>>>>> https://github.com/andrewfenn/Hardwar/blob/master/code/server/src/Server.cpp
>>>>>>>>> Client:
>>>>>>>>> https://github.com/andrewfenn/Hardwar/blob/master/code/client/tasks/src/NetworkTask.cpp
>>>>>>>>>
>>>>>>>>> On Thu, Nov 7, 2013 at 5:00 PM, Ruud van Gaal <ruud at racer.nl>
>>>>>>>>> wrote:
>>>>>>>>> > All I can say that in principle this works; I use this every day
>>>>>>>>> (a single
>>>>>>>>> > exe running both and a server and a client, where the client
>>>>>>>>> connects to its
>>>>>>>>> > own server).
>>>>>>>>> > Ruud
>>>>>>>>> >
>>>>>>>>> >
>>>>>>>>> > On Wed, Nov 6, 2013 at 2:37 PM, Krasimir Marinov <
>>>>>>>>> krasi at jklsemi.com> wrote:
>>>>>>>>> >>
>>>>>>>>> >> Hi,
>>>>>>>>> >>
>>>>>>>>> >> I’ve been trying to connect to the host:port that my ENetHost
>>>>>>>>> is bound to,
>>>>>>>>> >> i.e. connect and send to myself.
>>>>>>>>> >> Unfortunately this almost immediately results in event
>>>>>>>>> DISCONNECT.
>>>>>>>>> >>
>>>>>>>>> >> Looking at the archives I found the same problem raised 9 years
>>>>>>>>> ago (see
>>>>>>>>> >> below).
>>>>>>>>> >>
>>>>>>>>> >> Any reason for this behaviour?
>>>>>>>>> >>
>>>>>>>>> >> Regards,
>>>>>>>>> >> Krasimir
>>>>>>>>> >>
>>>>>>>>> >> [ENet-discuss] Connecting to self.
>>>>>>>>> >>
>>>>>>>>> >> Adam D. Moss adam at gimp.org
>>>>>>>>> >> Wed Dec 1 08:44:30 PST 2004
>>>>>>>>> >>
>>>>>>>>> >> Next message: [ENet-discuss] Connecting to self.
>>>>>>>>> >> Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
>>>>>>>>> >>
>>>>>>>>> >> ________________________________
>>>>>>>>> >>
>>>>>>>>> >> Hi!
>>>>>>>>> >> I have a funny problem. My app listens on a port and then
>>>>>>>>> attempts
>>>>>>>>> >> to connect to itself (for testing purposes, for now). But this
>>>>>>>>> >> merely eventually causes a DISCONNECT (presumably time-out)
>>>>>>>>> event,
>>>>>>>>> >> with no CONNECT.
>>>>>>>>> >>
>>>>>>>>> >> However, if I launch a second process and do the connect from
>>>>>>>>> >> there, the connection is fine.
>>>>>>>>> >>
>>>>>>>>> >> Am I being stupid for attempting to have a process be a client
>>>>>>>>> >> of its own server, or is there some unexpected strangeness which
>>>>>>>>> >> prevents an ENet server from being its own client?
>>>>>>>>> >>
>>>>>>>>> >> Thanks,
>>>>>>>>> >> --Adam
>>>>>>>>> >>
>>>>>>>>> >>
>>>>>>>>> >> _______________________________________________
>>>>>>>>> >> ENet-discuss mailing list
>>>>>>>>> >> ENet-discuss at cubik.org
>>>>>>>>> >> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>>>>>>> >>
>>>>>>>>> >
>>>>>>>>> >
>>>>>>>>> > _______________________________________________
>>>>>>>>> > ENet-discuss mailing list
>>>>>>>>> > ENet-discuss at cubik.org
>>>>>>>>> > http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>>>>>>> >
>>>>>>>>> _______________________________________________
>>>>>>>>> ENet-discuss mailing list
>>>>>>>>> ENet-discuss at cubik.org
>>>>>>>>> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> ENet-discuss mailing list
>>>>>>> ENet-discuss at cubik.org
>>>>>>> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>>>>
>>>>>>
>>>>>
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>>>>>
>>>>
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>
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