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Re: [SCTP-Discussion] Sctplib on Android


Chronological Thread 
  • From: Michael Tuexen <Michael.Tuexen AT micmac.franken.de>
  • To: Dag Ove <daggy2k AT hotmail.com>
  • Cc: Thomas Dreibholz <dreibh AT simula.no>, "sctp-discussion AT sctp.de" <sctp-discussion AT sctp.de>
  • Subject: Re: [SCTP-Discussion] Sctplib on Android
  • Date: Thu, 27 Feb 2014 15:26:06 +0100
  • List-archive: <http://lists.franken.de/pipermail/sctp-discussion>
  • List-id: SCTP Discussions <sctp-discussion.sctp.de>
On 27 Feb 2014, at 14:12, Dag Ove
<daggy2k AT hotmail.com>
wrote:

> In the SCTP-API of sctplib:
> 6.4 ULP-to-SCTP
> 6.4.1. sctp_initLibrary()
> "This function will open raw sockets for capturing SCTP packets (IPv4 and
> if possible, IPv6 too) from the network and initialize the timer list. It
> needs to be called before any other functions of the libsctp-library are
> called"
>
> I interpret the above line that function sctp_library() needs to be called
> regardless if using SCTP/IP or SCTP/UDP. Is it possible that if I only
> intend to use SCTP/UDP I dont need to call sctp_initLibrary() ?
No, you need to initialise the library.
>
> The context I want to use SCTP/UDP is as an example protocol for comparing
> it to HTTP/TCP and plain UDP when exchanging SOAP messages/XML data with a
> Web service server, so I simply want to use in a peer-to-peer system
> between Android and a java server.
OK.
>
> It had a look at usrsctp, but I had more trouble compiling the native C for
> Android, some classes/headers were missing (ifaddrs.h, umem.h, pthread.h).
> I am not very familiar with freeBSD.
I haven't build the library on a plain Android system, but you might want to
the build
process of Firefox and the corresponding files:
http://mxr.mozilla.org/mozilla-central/source/netwerk/sctp/src/
>
> SCTPLIB was easier to compile and install on Android, but the problem
> arised when" sctp_initLibrary()" calls "adl_init_adaptation_layer()", which
> in turn calls "adl_open_sctp_socket()". I don't understand why the function
> "adl_open_sctp_socket()" in adaptation.c tries to open a raw socket even if
> SCTP_OVER_UDP is set
> (ref lines 571-585 in
> https://github.com/dreibh/sctplib/blob/master/sctplib/sctp/adaptation.c)
>
> I this is not an implementation error, I would be very interrested in what
> functions to use to enable SCTP_over_UDP.
OK, I looked at the code. It is implemented using raw sockets. This could be
changed
for UDP encapsulation to not use raw sockets in the same way as it is done n
the usrsctp
code. I don't have to time to do that, maybe Thomas has. Not sure. It is not
very difficult...

Best regards
Michael
>
> Best Regards,
> Dag Ove,
> Norway
>
>
> > Subject: Re: [SCTP-Discussion] Sctplib on Android
> > From:
> > Michael.Tuexen AT micmac.franken.de
> > Date: Wed, 26 Feb 2014 14:22:08 +0100
> > CC:
> > sctp-discussion AT sctp.de;
> >
> > dreibh AT simula.no
> > To:
> > daggy2k AT hotmail.com
> >
> > On Feb 26, 2014, at 1:37 PM, Dag Ove
> > <daggy2k AT hotmail.com>
> > wrote:
> >
> > > Thank you for quick response!
> > >
> > > In "Documentation of the SCTP-Implementation - Release: sctplib-1.0"
> > > under "2 General Concepts" it says:
> > >
> > > "All of these functions may be made use of by simply linking the static
> > > libsctp-library to an application,
> > > and including the file sctp.h. As SCTP operates on top of IP, we chose
> > > to open a raw socket to catch
> > > all incoming packets with the IP protocol id byte set to 132 (=SCTP).
> > > For this, it is necessary that an
> > > application using the library functions have privileges to do so. On
> > > most Unix machines that means this
> > > application has to be run by root (i.e. be made setuid 0)."
> > And this is true for running SCTP/IP.
> > >
> > > After examining the adaption.c file I believe that this is the case
> > > also when the macro SCTP_OVER_UDP is set.
> > > Since Android does not allow opening of raw socket, i don't think
> > > sctplib can be used on Android
> > Then this is not implemented in an optimal way. Please note that I moved
> > from developing sctplib
> > to the FreeBSD kernel implementation and its port to userland, the
> > usrsctp library.
> >
> > From my perspective, the sctplib only get bug fixes. Not sure if someone
> > will change the above code.
> > Thomas: Do you have any intention to do so?
> > > without rooting the Android device.
> > >
> > > I haven't heard about usrsctp before, but will take a look at it!
> > It is the port of the FreeBSD kernel implementation to userland and is
> > used for RTCWeb by Firefox, Chrome and Opera.
> > > Does it provide the same functionality as sctplib?
> > It supports much more features and is actively maintained and used in a
> > couple
> > of browsers for RTCWeb. What is the context you want to use SCTP for?
> > > Do you know if it has been tested on Android before?
> > I think so, since some of the browsers run on Android...
> >
> > Best regards
> > Michael
> > >
> > > Best Regards,
> > > Dag Ove,
> > > Norway
> > >
> > >> Subject: Re: [SCTP-Discussion] Sctplib on Android
> > >> From:
> > >> Michael.Tuexen AT micmac.franken.de
> > >> Date: Wed, 26 Feb 2014 12:40:53 +0100
> > >> CC:
> > >> sctp-discussion AT sctp.de
> > >> To:
> > >> daggy2k AT hotmail.com
> > >>
> > >> On Feb 26, 2014, at 11:25 AM, Dag Ove
> > >> <daggy2k AT hotmail.com>
> > >> wrote:
> > >>
> > >>> Hello,
> > >>>
> > >>> I am trying to enable SCTP over UDP using the sctplib-1.0.15 as a
> > >>> native library in an Android app, using Androids Native Development
> > >>> Kit (NDK). The installation works since the Android kernel is Linux,
> > >>> but when I call the function "sctp_initLibrary();" I get in return "
> > >>> 1 - adaptation error ". The reason for this is that the function
> > >>> "adl_open_sctp_socket" fails and returns -1 when trying to create a
> > >>> raw socket "sfd = socket(af, SOCK_RAW, IPPROTO_UDP"
> > >>> Opening raw sockets in Android is not permitted unless having root
> > >>> access/superuser, and I don't want to root.
> > >>>
> > >>> My question is: Is it possible to use the sctplib-1.0.15 to send
> > >>> SCTP-over-UDP without having root or superuser?
> > >> Im not sure why a raw socket is used. For SCTP/UDP you only need UDP
> > >> sockets.
> > >> You can have a look at usrsctp, which is the FreeBSD stack running in
> > >> userland,
> > >> which does it like that. See
> > >> http://code.google.com/p/sctp-refimpl/source/browse/#svn%2Ftrunk%2FKERN%2Fusrsctp
> > >>
> > >> Best regards
> > >> Michael
> > >>>
> > >>> Best Regards,
> > >>> Dag Ove,
> > >>> Norway
> > >>> _______________________________________________
> > >>> sctp-discussion mailing list
> > >>> sctp-discussion AT sctp.de
> > >>> http://www.sctp.de/mailman/listinfo/sctp-discussion
> > >>
> >



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