| In the gstreamer plugin I want to provide a plugin property named
| ccid, where the programmer will set or get the current ccid. Is dccp
| implementation for linux already prepared to support this mechanism
| through feature negotiation (or something related via
| setsockopt/getsockopt)?
Yes it is - all the necessary code is in the test tree, but it is not
exhaustively documented so far (but all set/getsockopts are documented
in Documentation/networking/dccp.txt).
Here is a short test program to document:
/*--*/
#include err.h
uint8_tccid = 3,/* the CCID you want to set */
ccids[4],/* for getting the available CCIDs, should be
large enough */
tx_ccid, rx_ccid;
socklen_t len = sizeof(ccids);
intsockfd = socket(AF_XXX, SOCK_DCCP, 0);
/*
* Determine which CCIDs are available on the host
*/
if (getsockopt(sockfd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS, ccids, len)
0)
err(1, Can not determine available CCIDs);
ccid = my_favourite_ccid;
if (!found_in_array(ccid, ccids, sizeof(ccids))
err(1, CCID %d not supported, ccid);
/*
* The following calls need to be made before establishing the connection, i.e.
before
* calling listen() or connect()
*/
if (setsockopt(sockfd, SOL_DCCP, DCCP_SOCKOPT_CCID, ccid, sizeof(ccid)) 0)
err(1, Can not set CCID);
/*
Alternatively, if you want to set different CCIDs for each direction:
if (setsockopt(sockfd, SOL_DCCP, DCCP_SOCKOPT_TX_CCID, tx_ccid,
sizeof(tx_ccid)) 0)
err(1, Can not set TX CCID);
if (setsockopt(sockfd, SOL_DCCP, DCCP_SOCKOPT_RX_CCID, rx_ccid,
sizeof(rx_ccid)) 0)
err(1, Can not set RX CCID);
NOTE: In the above, single values are used. If you want choice, you can pass
an ordered
array (preferred CCID first), which will then be used for
feature-negotiation.
If you are negotiating with single values, it will only work when both
sides pick
the same value.
*/
/*
* Once the connection is established, you can find out the results of the
feature negotiation
* by calling getsocktopt() with DCCP_SOCKOPT_TX_CCID/DCCP_SOCKOPT_RX_CCID
*/
/*--*/
Looking forward to the gstreamer plugin - can you please announce on the list.
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