[Nice] Starting with libnice
Youness Alaoui
youness.alaoui at collabora.co.uk
Thu Nov 17 13:42:53 PST 2011
On 11/16/2011 08:30 PM, Tiago Sá wrote:
> Hi again Youness,
> thanks a lot for your help.
> I believe I solved the problems you pointed before.
> I am using a dumb method to exchange candidates. I write them to file and
> exchange them using a ftp server (I will improve it later).
>
> So, the way I run it is:
> (HostA) ./client l
> (HostB) ./client r
> //local candidates are gathered and written to file
> (HostA) put leftCands.bin on FTP and get rightCands.bin
> (HostB) put rightCands.bin on FTP and get leftCands.bin
> //read local credentials and write them on the remote host
>
> I am using a relay server, that should work as a last resort. But during the
> local candidate gathering, sometimes it gets a relayed candidate, but most of
> the times it doesn't. Can it be related with timeouts?
It's possible the timeouts are affecting it, but I doubt it, usually the RTT
would be 200ms, but if you don't get a response from the relay or the stun
server, it will retry 4 times until it times out after about 3 seconds.
It's possible though that the server has a limit on the number of allocations
you can create (probably 5) and if you are testing your app and it creates 2
allocations each time (one for each side), then it's possible the server starts
rejecting your allocation requests (each time you want to use TURN, it will ask
the server to allocate a port for you for that specific connection, so you have
the same settings but one port for each stream/component).
If that's the case, maybe that's why it sometimes works (when the allocation
times out from the server). libnice should technically deallocate when the
stream is destroyed, so maybe catch your Ctrl-C and do an unref on the agent
before returning from the main.
>
> Either way, it can never get a pair a establish a connection. :(
> I don't have a clue why this happens..
A log + wireshark dump might be helpful in this case. You can enable logging with :
export NICE_DEBUG=all
>
> Can you please have a look?
The code looks sane enough.. apart from the obvious method of exchanging
candidates which isn't "optimal". One thing I noticed though, you just fwrite
the whole structure, but note that there are pointers in the structure that will
be written as is to the file, and not their content. I'm thinking of
username+password (but those should be NULL if you use the RFC5245 compatibility
mode) but mostly the turn structure (which is just for local candidates and
wouldn't be used anyways for remote ones, but it's best to set it to NULL to
avoid possible crashes).
>
> Cheers,
> Tiago
>
>
> On Fri, Nov 4, 2011 at 2:03 PM, Youness Alaoui <youness.alaoui at collabora.co.uk
> <mailto:youness.alaoui at collabora.co.uk>> wrote:
>
> Hi again Tiago,
>
> For the remote candidates, you will need a third party server to exchange that
> information, usually the candidates would be sent over SIP or XMPP for example.
> ICE cannot work if you don't have a third party server with which you can
> reliably exchange candidates. For testing purposes you could have it print the
> candidates to stdout, and you could copy/paste that into stdin of the other
> instance and have it parse the input.. or you could hardcode a port to connect
> to and do the candidate exchange.. there's no easy way of doing that though.
> You cannot hardcode the candidates because the port used will be random
> everytime, also, you will need to exchange the randomly generated
> username/password (nice_agent_get_local_credentials +
> nice_agent_set_remote_credentials) to make the connectivity checks work.
>
> As for your example, here are a few comments :
> 1 - you call the nice_agent_set_relay_info with stream_id being uninitialized,
> you must call it *after* you do the nice_agent_add_stream...
> 2 - you don't need those GValues, you can just do
> g_object_set (G_OBJECT(agent),
> "stun-server", "66.228.45.110",
> "stun-server-port", 3478,
> NULL);
> 3 - You shouldn't set the remote credentials as the same as the local ones
> 4 - In your print_candidate_info, you may also want to print the port used.
>
> I hope this helps, let me know if you have further questions.
>
> Youness.
>
>
> On 11/03/2011 12:57 PM, Tiago Sá wrote:
> > Hi Youness,
> >
> > I have been trying to create a simple application based on the first link you
> > pointed before.
> > Thanks for the tips you gave me. I have a couple of questions though, if
> you can
> > help me.
> >
> > I need to find a way to get the remote candidates passed from a peer to
> another.
> > Can you point an easy way to do that?
> > Could I hardcode the remote candidates list, for testing purposes?
> >
> > Right now, I only get two local candidates (HOST and SERVER_REFLEXIVE).
> > I am trying to use the numb TURN server, shouldn't I get a RELAYED
> candidate too?
> >
> > I am attaching the code. Can you please have a look at the code and check
> where
> > the error could be?
> >
> > Thanks for helping!
> >
> > Regards,
> > Tiago Sá
> >
> >
> > On Wed, Oct 19, 2011 at 10:53 PM, Youness Alaoui
> <youness.alaoui at collabora.co.uk <mailto:youness.alaoui at collabora.co.uk>
> > <mailto:youness.alaoui at collabora.co.uk
> <mailto:youness.alaoui at collabora.co.uk>>> wrote:
> >
> > Hi,
> >
> > Welcome to the world of libnice :)
> > Yes, doing NAT traversal is far from being easy, the only solution is
> pretty
> > much to use the ICE specification and that's not easy to implement, so
> that's
> > why you'd need to use libnice.
> >
> > For an example, you can have a look at the unit tests, like
> > tests/test-fullmode.c for example, although that does a lot of stuff.
> You can
> > see a quick example in the documentation for NiceAgent :
> > http://nice.freedesktop.org/libnice/NiceAgent.html
> >
> > For smaller examples, you can look at the libnice mailing list
> archives, some
> > people posted their example code where they were having problems. For
> example, a
> > very simple example can be seen here :
> > http://lists.freedesktop.org/archives/nice/2011-January/000404.html
> > But make sure to click on the "Next message" to read the whole thread
> because
> > that example had a bug that I explained how to fix in the following
> emails.
> > Same for this thread :
> > http://lists.freedesktop.org/archives/nice/2011-October/000434.html
> >
> > I hope that helps,
> > Youness.
> >
> > On 10/19/2011 09:58 AM, Tiago Sá wrote:
> > > Hi all,
> > >
> > > my name is Tiago Sá, I am a junior researcher from Portugal and this
> is my
> > first
> > > mail to this list.
> > > I have a NAT traversal problem to solve and I have been looking for
> a solution
> > > during the last weeks, which, as I found out, is not so trivial as I
> > thought before.
> > > As stated on the libnice homepage, libnice seems to be what I am
> looking for:
> > >
> > > "ICE is useful for applications that want to establish peer-to-peer
> > UDP data
> > > streams. It automates the process of traversing NATs and
> provides security
> > > against some attacks. It also allows applications to create reliable
> > streams
> > > using a TCP over UDP layer."
> > >
> > >
> > > I have been looking for the provided documentation and I am feeling kind
> > of lost.
> > > Is there any example application or tutorial to get started?
> > > Could you please share a basic application of this kind or point me a
> > direction?
> > >
> > >
> > > Thanks in advance for your help.
> > >
> > > Regards,
> > > Tiago Sá
> > >
> > > --
> > > Tiago Sá
> > > Universidade do Minho, Braga - Portugal
> > >
> > > http://about.me/tiagosa/
> > >
> > >
> > >
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> >
> >
> > --
> > Tiago Sá
> > Universidade do Minho, Braga - Portugal
> > www.tiagosa.com <http://www.tiagosa.com> <http://www.tiagosa.com>
> >
>
>
>
>
>
> --
> Tiago Sá
> Universidade do Minho, Braga - Portugal
> www.tiagosa.com <http://www.tiagosa.com>
>
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