[gnutls-help] the problem about "stream usage" in dtls/sctp

[Wei Cheng]

i have made a  mistake here.
i read the source code today,i found that the first byte of the msg what be
sent in my push function is the msg type.
i should have a good look at the source code.

thanks!


2017-05-11 23:26 GMT+08:00 Wei Cheng <chengwei.clx at gmail.com>:

> hi,guys!
>
> i have read the rfc6083 which  describes the usage of the Datagram
> Transport Layer Security (DTLS) protocol over the Stream Control
> Transmission Protocol (SCTP).
>
> "stream usage " is as follows:
> 4.4.  Stream Usage
>    All DTLS messages of the ChangeCipherSpec, Alert, or Handshake
>    protocol MUST be transported on stream 0 with unlimited reliability
>    and with the ordered delivery feature.
>    DTLS messages of the ApplicationData protocol SHOULD use multiple
>    streams other than stream 0; they MAY use stream 0 for everything if
>    they do not care about minimizing head of line blocking.
>
>
> i write a push_function .like that:
> static ssize_t push_func(gnutls_transport_ptr_t p, const void *data,
> size_t size)
> {
>     priv_data_st *priv = p;
>     int ret;
>     //  i sent msg on stream #0
>     ret = sctp_sendmsg(priv->fd, data,size ,NULL, 0,0, 0,0, 0,0);
>     if (ret < 0)
>          printf("fail to sent msg \n");
>      else
>          printf("success to sent msg in push\n");
>      return ret;
> }
>
> i use gnutls_transpoet_set_push_fnuction to register my push function,
> so that all message would be sent by my push_function.
>
>
> i want to sent alert,handshake,changesuite on stream #0, while appilcaiton
> data is sent on others streams.
> in push_function,all data is already encryped,
> how i can distinguish which kind of msg it is ?
> how should i write my push_function?
> i doubt that i am wrong in this part.
>
> i sorry about my poor english.
> thanks any advices!
> thanks in advance!
>
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