[openssl-users] DTLS over UDP

[Nivedita]

Hi Michael,

Would you please let me  know whether this  new release of
openssl-1.1.1-pre3  supports DTLS over udp for SIP protocol using
dtlsv1_accept method.

Regards,
Nivedita

On Wed, Feb 21, 2018 at 11:54 AM, Nivedita <maddi.nivedita at gmail.com> wrote:

> Hi Michael,
>
> Please find the response inline and also i have attached the pcap for your
> reference.
>
> ip.src ==22.33.40.20 is the search criteria for pcap dump.
> Regards,
> Nivedita
>
> On Tue, Feb 20, 2018 at 12:13 AM, Michael Richardson <mcr at sandelman.ca>
> wrote:
>
>>
>> Nivedita <maddi.nivedita at gmail.com> wrote:
>>     >> Nivedita <maddi.nivedita at gmail.com> wrote:
>>
>>     >>> I am trying to establish DTLS over UDP connection by using
>>     >>> DTLSv1_listen method .
>>
>>     >>> I have followed the below steps - 1. Created a server socket
>>     >>> and using
>>     >>> this socket created bio and ssl object. bio =
>>     >>> BIO_new_dgram(VI_sock,BIO_NOCLOSE)) SSL_set_bio
>>     >>> (ssl,VP_bio,VP_bio);
>>
>>     >>> 2. Enable cookie exchange on SSL object. SSL_set_options(ssl,
>>     >>> SSL_OP_COOKIE_EXCHANGE);
>>
>>     >>> 3. Then started listening using dtlsv1_listen for the new
>>     >>> client
>>     >>> connections. Once dtlsv1_listen is successful and i got the
>>     >>> peer
>>     >>> address.
>>
>>     mcr> okay.
>>
>>
>>     >> Nivedita- All the above mentioned steps i am doing on server
>>     >> side . On the
>>     >> client side i have already initiated ssl_connect.
>>     >> On the server side when i am listening using dtlsv1_listen
>>     >> method -
>>
>>     >>> 4. Once i got the peer address , i am creating one more socket
>>     >>> 5. With the new socket i tried to connect to peer address.
>>
>>    >> Then once i got the client address from the dtlsv1_listen method,
>>     >> i am creating one more socket and trying to connect to this client
>>      >> address.
>>
>> >I think that I see what is wrong with your flow... you haven't taken the
>> >packet off the original socket, so SSL_accept is still looking for it.
>>
>> >The flow is supposed to be:
>>    >  1) client sends ClientHello
>>    Nivedita-  Client is sending the client hello.
>>
>
>
>>      >2) DTLSv1_listen() sees it, and sends a HelloVerifyRequest
>>        > (I assume you have filled in the cookie callbacks. I think that
>>        > perhaps there should be good cryptographic defaults available in
>>         >the library.  Maybe there are, and I'm ignorant of them)
>>
>>        Nivedita-  Yes, I have attached all the cookies  and server is
> responding with hello verify request.
>
>
>>  >   3) Client sends ClientHello w/cookie.
>>  >    DTLSv1_listen() then sees that and tweaks the SSL* to indicate that
>>  >     the cookie has been accepted.  Note that the packet is *LEFT*
>>  >      on the incoming socket so that SSL_accept() can process it.
>>   >     This is one the places where the DTLSv1_listen() API is rather
>>   >      hard to use in my opinion.
>>
>    Nivedita-     Now after Hello verify request is done, client sends the
> client hello with cookie.
>                       Now i have done SSL_accept on the same server
> socket.[ means the same socket on which dtlsv1_listen was triggered]
>
>>
>> >    4) You make up new sockets, etc.
>>
>       Nivedita-         After ssl_accept is done , i have created one more
> socket, and tried to connect to client addr and set the bio on the new
> socket.
>
>                VI_sock_id = socket(client_addr.ss_family,SOCK_DGRAM,0);
>
>                VI_status = connect(VI_sock_id, (struct sockaddr
> *)&client_addr,  sizeof(struct sockaddr_storage));
>
>>
>
>
>
>> >  5) But, you need to call SSL_accept() once with the **old socket** to
>> >      process packet that listen() left on it, and then you can switch
>> the
>> >       FD over!  Of course, you probably want to make sure that
>> SSL_accept()
>> >      sends the reply correctly.
>>
>
>     Nivedita-   As suggested i have done the ssl_accept on the same socket
> on which dtlsv1_listen was triggered.
>                     After ssl_accept i am trying to change the fd , so
> that the incoming data  should come to new fd , instead of old one.  But
> still traffic is coming on old fd[dtlsv1 fd]
>
>                    VI_res = SSL_accept(VP_ssl);
>                    VI_res = BIO_set_fd(SSL_get_rbio(VP_
> ssl),VI_sock_id,BIO_NOCLOSE);
>                    VI_res = BIO_ctrl(SSL_get_rbio(VP_ssl),BIO_CTRL_DGRAM_SET_CONNECTED,
> 0, &client_addr);
>
>       Please let me know your inputs i, so that traffic has to move from
> old fd to new fd.
>
>
>> What I do in my proposed DTLSv1_accept() API is that I move the data
>> From the incoming socket to the new BIO's incoming queue:
>> https://github.com/mcr/openssl/blob/dtls-listen-refactor/
>> ssl/d1_lib.c#L964
>>
>>     /* At this point, there is a real ClientHello in serv->init_buf */
>>     memcpy(rb->buf, serv->init_buf->data, serv->init_num);
>>     rb->offset = 0;
>>     rb->left   = serv->init_num;
>>
>> and then remove the packet from the incoming socket.  The situation is
>> then returned like this so that the new sockets can be setup, but the
>> incoming SSL_accept() BIO is stuffed with the correct (cookie-full)
>> ClientHello, and replies will go to the right place with the right source
>> address.  I hope to get these patches accepted for the March 11 freeze,
>> but you might not want to depend upon it.
>>
>>
>> --
>> ]               Never tell me the odds!                 | ipv6 mesh
>> networks [
>> ]   Michael Richardson, Sandelman Software Works        | network
>> architect  [
>> ]     mcr at sandelman.ca  http://www.sandelman.ca/        |   ruby on
>> rails    [
>>
>>
>> --
>> openssl-users mailing list
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>>
>>
>
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