A.4 Generating SDES RTCP Packets

This function builds one SDES chunk into buffer b composed of argc items supplied in arrays type , value and length b

   char *rtp_write_sdes(char *b, u_int32 src, int argc,
                        rtcp_sdes_type_t type[], char *value[],
                        int length[])
   {
       rtcp_sdes_t *s = (rtcp_sdes_t *)b;
       rtcp_sdes_item_t *rsp;
       int i;
       int len;
       int pad;

       /* SSRC header */
       s->src = src;
       rsp = &s->item[0];

       /* SDES items */
       for (i = 0; i < argc; i++) {
           rsp->type = type[i];
           len = length[i];
           if (len > RTP_MAX_SDES) {
               /* invalid length, may want to take other action */
               len = RTP_MAX_SDES;
           }
           rsp->length = len;
           memcpy(rsp->data, value[i], len);
           rsp = (rtcp_sdes_item_t *)&rsp->data[len];
       }

       /* terminate with end marker and pad to next 4-octet boundary */
       len = ((char *) rsp) - b;
       pad = 4 - (len & 0x3);
       b = (char *) rsp;
       while (pad--) *b++ = RTCP_SDES_END;

       return b;
   }