/** * Sends acknowledgment for open channel request on given SCTP stream ID. * * @param sid SCTP stream identifier to be used for sending ack. */ private void sendOpenChannelAck(int sid) throws IOException { // Send ACK byte[] ack = MSG_CHANNEL_ACK_BYTES; int sendAck = sctpSocket.send(ack, true, sid, WEB_RTC_PPID_CTRL); if (sendAck != ack.length) { logger.error("Failed to send open channel confirmation"); } }
/** * Opens new WebRTC data channel using specified parameters. * * @param type channel type as defined in control protocol description. Use 0 for "reliable". * @param prio channel priority. The higher the number, the lower the priority. * @param reliab Reliability Parameter<br> * This field is ignored if a reliable channel is used. If a partial reliable channel with * limited number of retransmissions is used, this field specifies the number of * retransmissions. If a partial reliable channel with limited lifetime is used, this field * specifies the maximum lifetime in milliseconds. The following table summarizes this:<br> * </br> * <p>+------------------------------------------------+------------------+ | Channel Type | * Reliability | | | Parameter | * +------------------------------------------------+------------------+ | * DATA_CHANNEL_RELIABLE | Ignored | | DATA_CHANNEL_RELIABLE_UNORDERED | Ignored | | * DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | Number of RTX | | * DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | Number of RTX | | * DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | Lifetime in ms | | * DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | Lifetime in ms | * +------------------------------------------------+------------------+ * @param sid SCTP stream id that will be used by new channel (it must not be already used). * @param label text label for the channel. * @return new instance of <tt>WebRtcDataStream</tt> that represents opened WebRTC data channel. * @throws IOException if IO error occurs. */ public synchronized WebRtcDataStream openChannel( int type, int prio, long reliab, int sid, String label) throws IOException { if (channels.containsKey(sid)) { throw new IOException("Channel on sid: " + sid + " already exists"); } // Label Length & Label byte[] labelBytes; int labelByteLength; if (label == null) { labelBytes = null; labelByteLength = 0; } else { labelBytes = label.getBytes("UTF-8"); labelByteLength = labelBytes.length; if (labelByteLength > 0xFFFF) labelByteLength = 0xFFFF; } // Protocol Length & Protocol String protocol = WEBRTC_DATA_CHANNEL_PROTOCOL; byte[] protocolBytes; int protocolByteLength; if (protocol == null) { protocolBytes = null; protocolByteLength = 0; } else { protocolBytes = protocol.getBytes("UTF-8"); protocolByteLength = protocolBytes.length; if (protocolByteLength > 0xFFFF) protocolByteLength = 0xFFFF; } ByteBuffer packet = ByteBuffer.allocate(12 + labelByteLength + protocolByteLength); // Message open new channel on current sid // Message Type packet.put((byte) MSG_OPEN_CHANNEL); // Channel Type packet.put((byte) type); // Priority packet.putShort((short) prio); // Reliability Parameter packet.putInt((int) reliab); // Label Length packet.putShort((short) labelByteLength); // Protocol Length packet.putShort((short) protocolByteLength); // Label if (labelByteLength != 0) { packet.put(labelBytes, 0, labelByteLength); } // Protocol if (protocolByteLength != 0) { packet.put(protocolBytes, 0, protocolByteLength); } int sentCount = sctpSocket.send(packet.array(), true, sid, WEB_RTC_PPID_CTRL); if (sentCount != packet.capacity()) { throw new IOException("Failed to open new chanel on sid: " + sid); } WebRtcDataStream channel = new WebRtcDataStream(sctpSocket, sid, label, false); channels.put(sid, channel); return channel; }