[ENet-discuss] Connecting to self (resolved)
Lee Salzman
lsalzman at gmail.com
Mon Nov 18 04:21:57 PST 2013
For better or worse I committed a version of this fix to the repo. I didn't
have time to actually test it out, though, so I will, uh, let you guys
beta-test this one. ;)
On Tue, Nov 12, 2013 at 12:45 PM, Lee Salzman <lsalzman at gmail.com> wrote:
> 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
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>>>>>>>>>> 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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>>>>>
>>>>
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>>
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>
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