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/*****************************************************************************
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* rtcp.c: RTCP stream output support
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*****************************************************************************
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* Copyright © 2007 Rémi Denis-Courmont
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*****************************************************************************/
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/*****************************************************************************
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*****************************************************************************/
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#include <vlc_common.h>
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#include <vlc_block.h>
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#include <vlc_network.h>
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* NOTE on RTCP implementation:
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* - there is a single sender (us), no conferencing here! => n = sender = 1,
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* - as such we need not bother to include Receiver Reports,
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* - in unicast case, there is a single receiver => members = 1 + 1 = 2,
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* and obviously n > 25% of members,
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* - in multicast case, we do not want to maintain the number of receivers
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* and we assume it is big (i.e. than 3) because that's what broadcasting is
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* - it is assumed we_sent = true (could be wrong), since we are THE sender,
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* - we always send SR + SDES, while running,
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* - FIXME: we do not implement separate rate limiting for SDES,
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* - we do not implement any profile-specific extensions for the time being.
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size_t length; /* RTCP packet length */
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uint8_t payload[28 + 8 + (2 * 257) + 8];
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int handle; /* RTCP socket handler */
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uint32_t packets; /* RTP packets sent */
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uint32_t bytes; /* RTP bytes sent */
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unsigned counter; /* RTP packets sent since last RTCP packet */
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rtcp_sender_t *OpenRTCP (vlc_object_t *obj, int rtp_fd, int proto,
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char src[NI_MAXNUMERICHOST];
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if (net_GetSockAddress (rtp_fd, src, &sport))
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/* RTP/RTCP mux: duplicate the socket */
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WSAPROTOCOL_INFO info;
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WSADuplicateSocket (rtp_fd, GetCurrentProcessId (), &info);
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fd = WSASocket (info.iAddressFamily, info.iSocketType, info.iProtocol,
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/* RTCP on a separate port */
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char dst[NI_MAXNUMERICHOST];
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if (net_GetPeerAddress (rtp_fd, dst, &dport))
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fd = net_OpenDgram (obj, src, sport, dst, dport, AF_UNSPEC, proto);
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rtcp = malloc (sizeof (*rtcp));
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rtcp->bytes = rtcp->packets = rtcp->counter = 0;
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ptr = (uint8_t *)strchr (src, '%');
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*ptr = '\0'; /* remove scope ID frop IPv6 addresses */
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ptr[0] = 2 << 6; /* V = 2, P = RC = 0 */
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ptr[1] = 200; /* payload type: Sender Report */
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SetWBE (ptr + 2, 6); /* length = 6 (7 double words) */
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memset (ptr + 4, 0, 4); /* SSRC unknown yet */
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SetQWBE (ptr + 8, NTPtime64 ());
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memset (ptr + 16, 0, 12); /* timestamp and counters */
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/* Source description */
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ptr[0] = (2 << 6) | 1; /* V = 2, P = 0, SC = 1 */
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ptr[1] = 202; /* payload type: Source Description */
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uint8_t *lenptr = ptr + 2;
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memset (ptr + 4, 0, 4); /* SSRC unknown yet */
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ptr[0] = 1; /* CNAME - mandatory */
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assert (NI_MAXNUMERICHOST <= 256);
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ptr[1] = strlen (src);
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memcpy (ptr + 2, src, ptr[1]);
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static const char tool[] = PACKAGE_STRING;
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ptr[0] = 6; /* TOOL */
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ptr[1] = (sizeof (tool) > 256) ? 255 : (sizeof (tool) - 1);
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memcpy (ptr + 2, tool, ptr[1]);
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while ((ptr - sdes) & 3) /* 32-bits padding */
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SetWBE (lenptr, (ptr - sdes - 1) >> 2);
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rtcp->length = ptr - rtcp->payload;
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void CloseRTCP (rtcp_sender_t *rtcp)
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uint8_t *ptr = rtcp->payload;
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uint64_t now64 = NTPtime64 ();
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SetQWBE (ptr + 8, now64); /* Update the Sender Report timestamp */
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ptr[0] = (2 << 6) | 1; /* V = 2, P = 0, SC = 1 */
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ptr[1] = 203; /* payload type: Bye */
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memcpy (ptr + 4, rtcp->payload + 4, 4); /* Copy SSRC from Sender Report */
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/* We are THE sender, so we are more important than anybody else, so
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* we can afford not to check bandwidth constraints here. */
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send (rtcp->handle, rtcp->payload, rtcp->length, 0);
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net_Close (rtcp->handle);
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void SendRTCP (rtcp_sender_t *restrict rtcp, const block_t *rtp)
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if ((rtcp == NULL) /* RTCP sender off */
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|| (rtp->i_buffer < 12)) /* too short RTP packet */
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/* Updates statistics */
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rtcp->bytes += rtp->i_buffer;
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rtcp->counter += rtp->i_buffer;
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/* 1.25% rate limit */
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if ((rtcp->counter / 80) < rtcp->length)
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uint8_t *ptr = rtcp->payload;
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uint32_t last = GetDWBE (ptr + 8); // last RTCP SR send time
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uint64_t now64 = NTPtime64 ();
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if ((now64 >> 32) < (last + 5))
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return; // no more than one SR every 5 seconds
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memcpy (ptr + 4, rtp->p_buffer + 8, 4); /* SR SSRC */
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SetQWBE (ptr + 8, now64);
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memcpy (ptr + 16, rtp->p_buffer + 4, 4); /* RTP timestamp */
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SetDWBE (ptr + 20, rtcp->packets);
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SetDWBE (ptr + 24, rtcp->bytes);
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memcpy (ptr + 28 + 4, rtp->p_buffer + 8, 4); /* SDES SSRC */
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if (send (rtcp->handle, ptr, rtcp->length, 0) == (ssize_t)rtcp->length)