rtppkt.h

ccrtp, ccrtp-1.5.0.tar.gz

// Copyright (C) 2002 Federico Montesino Pouzols <[e-mail]>.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
//
// This exception applies only to the code released under the name GNU
// ccRTP.  If you copy code from other releases into a copy of GNU
// ccRTP, as the General Public License permits, the exception does
// not apply to the code that you add in this way.  To avoid misleading
// anyone as to the status of such modified files, you must delete
// this exception notice from them.
//
// If you write modifications of your own for GNU ccRTP, it is your choice
// whether to permit this exception to apply to your modifications.
// If you do not wish that, delete this exception notice.
//

#ifndef	CCXX_RTP_RTPPKT_H_
#define CCXX_RTP_RTPPKT_H_

#include <ccrtp/base.h>
#include <ccrtp/formats.h>
#include <ccrtp/CryptoContext.h>

#ifdef CCXX_NAMESPACES
namespace ost {
#endif

/**
 * @file rtppkt.h
 *
 * @short RTP packets handling.
 **/

/**
 * @defgroup rtppacket RTP data packets manipulation.
 * @{
 **/

/**
 * @class RTPPacket
 * @short A base class for both IncomingRTPPkt and OutgoingRTPPkt.
 *
 * Provides common low level header structures and related
 * methods. This class provides an interface that allows for partial
 * and generic manipulation of RTP data packets. Values are returned
 * in host order, except raw structures, which are returned as they
 * are sent through the network.
 *
 * @author David Sugar <[e-mail]>
 **/

class CryptoContext;

class  __EXPORT RTPPacket
{
private:
	struct RTPFixedHeader;
	struct RTPHeaderExt;

public:
	/**
	 * Constructor, construct a packet object given the memory
	 * zone its content (header and payload) is stored. Commonly
	 * used to build RTPPacket objects from incoming data.
	 *
	 * @param block whole packet
	 * @param len total length (header + payload + padding) of the
	 *        packet
	 * @param duplicate whether to memcopy the packet. At present,
	 *        this feature is not used.
	 * @note used in IncomingRTPPkt.
	 **/
	RTPPacket(const unsigned char* const block, size_t len,
		  bool duplicate = false);

	/**
	 * Construct a packet object without specifying its real
	 * content yet. Commonly used for outgoing packets. Header
	 * fields and payload must be filled in by another methods or
	 * by a derived constructor.
	 *
	 * @param hdrlen length of the header (including CSRC and extension).
	 * @param plen payload length.
	 * @param paddinglen pad packet to a multiple of paddinglen
	 * @note used in OutgoingRTPPkt.
	 */
        RTPPacket(size_t hdrlen, size_t plen, uint8 paddinglen, CryptoContext* pcc= NULL);

	/**
	 * Get the length of the header, including contributing
	 * sources identifiers and header extension, if present.
	 *
	 * @return number of octets.
	 **/
	inline uint32
	getHeaderSize() const
	{ return hdrSize; }

	/**
	 * @return pointer to the payload section of the packet.
	 **/
	inline const uint8* const
	getPayload() const
	{ return (uint8*)(buffer + getHeaderSize()); }

	/**
	 * @return length of the payload section, in octets.
	 **/
	inline uint32
	getPayloadSize() const
	{ return payloadSize; }

	/**
	 * @return value of the PT header field.
	 **/
	inline PayloadType
	getPayloadType() const
	{ return static_cast<PayloadType>(getHeader()->payload); }

	/**
	 * @return value of the sequence number header field, in host order.
	 **/
	inline uint16
	getSeqNum() const
	{ return cachedSeqNum; }

	/**
	 * @return packet timestamp in host order.
	 **/
	inline uint32
	getTimestamp() const
	{ return cachedTimestamp; }

	/**
	 * @return RTP protocol version of packet.
	 **/
	inline uint8
	getProtocolVersion() const
	{ return getHeader()->version; }

	/**
	 * Ask whether the packet contains padding bytes at the end
	 * @return true if the header padding bit is 1.
	 **/
	inline bool
	isPadded() const
	{ return getHeader()->padding; }

	/**
	 * Get the number of octets padding the end of the payload
	 * section.
	 *
	 * @return Padding length in octets.
	 **/
	inline uint8
	getPaddingSize() const
	{ return buffer[total - 1]; }

	/**
	 * Ask whether the packet is marked (for isntance, is a new
	 * talk spurt in some audio profiles).
	 *
	 * @return true is the header marker bit is 1.
	 **/
	inline bool
	isMarked() const
	{ return getHeader()->marker; }

	/**
	 * Ask whether the packet contains header extensions.
	 *
	 * @return true if the header extension bit is 1.
	 **/
	inline bool
	isExtended() const
	{ return getHeader()->extension; }

	/**
	 * Get the number of contributing sources specified in the
	 * packet header.
	 **/
	inline uint16
	getCSRCsCount() const
	{ return getHeader()->cc; }

	/**
	 * Get the 32-bit identifiers of the contributing sources for
	 * the packet as an array, of length getCSRCsCount().
	 *
	 * @return An array of CSRC identifiers as they are in the
	 * packet (in network order).
	 **/
	inline const uint32*
	getCSRCs() const
	{ return static_cast<const uint32*>(&(getHeader()->sources[1])); }

	/**
	 * Get the first 16 bits (in network order) of the header of
	 * the RTP header extension. Its meaning is undefined at this
	 * level.
	 *
	 * @return 0 if the packet has no header extension, otherwise
	 *         the first 16 bits of the header extension, in
	 *         network order.
	 *
	 * @note 0 could be a valid value for the first 16 bits, in
	 *         that case RTPPacket::isExtended() should be use.
	 **/
	inline uint16
	getHdrExtUndefined() const
	{ return (isExtended()? getHeaderExt()->undefined : 0); }

	/**
	 * Get the length (in octets) of the data contained in the
	 * header extension. Note that this length does not include
	 * the four octets at the beginning of the header extension.
	 *
	 * @return 0 if the packet has no header extension, otherwise
	 *         the length.
	 *
	 * @note 0 is a valid value for this field, so
	 *       RTPPacket::isExtended() should be used.
	 **/
	inline uint32
	getHdrExtSize() const
	{ return (isExtended()?
		  (static_cast<uint32>(ntohs(getHeaderExt()->length)) << 2) :
		  0); }

	/**
	 * Get the content of the header extension.
	 *
	 * @return NULL if the packet has no header extension, otherwise
	 *         a pointer to the packet header extension content.
	 **/
	inline const unsigned char*
	getHdrExtContent() const
	{ return (isExtended() ?
		  (reinterpret_cast<const unsigned char*>(getHeaderExt()) +
		   sizeof(RTPHeaderExt)) :
		  NULL); }

	/**
	 * Get the raw packet as it will be sent through the network.
	 *
	 * @return memory zone where the raw packet structure is
	 *         stored in.
	 **/
	inline const unsigned char* const
	getRawPacket() const
	{ return buffer; }

	/**
	 * Get the raw packet length, including header, extension,
	 * payload and padding.
	 *
	 * @return size of the raw packet structure.
	 **/
	inline uint32
	getRawPacketSize() const
	{ return total; };

        inline uint32
        getRawPacketSizeSrtp() const
        { return total + srtpLength; };

        inline size_t
	getSizeOfFixedHeader() const
	{ return sizeof(RTPFixedHeader); }

protected:
	/**
	 * Destructor, free the buffer provided in the constructor.
	 **/
	inline virtual ~RTPPacket()
	{ endPacket(); };

	/**
	 * Free memory allocated for the packet.
	 **/
	void
	endPacket();

	/**
	 * Return low level structure for the header of the packet.
	 *
	 * @return RTPFixedHeader pointer to the header of the packet.
	 **/
	inline RTPFixedHeader*
	getHeader() const
	{ return reinterpret_cast<RTPFixedHeader*>(buffer); }

	inline void
	setExtension(bool e)
	{ getHeader()->extension = e; }

	/**
	 * Get a pointer to RTPHeaderExt pointing after the RTP header
	 * (fixed part plus contributing sources). No check for
	 * for the X bit is done.
	 *
	 * @return header extension if present, garbage if not.
	 **/
	inline const RTPHeaderExt*
	getHeaderExt() const
	{
         uint32 fixsize = sizeof(RTPFixedHeader) + (getHeader()->cc << 2);
	 return (reinterpret_cast<RTPHeaderExt*>(buffer + fixsize));
	}

	/**
	 * Obtain the absolute timestamp carried in the packet header.
	 *
	 * @return 32-bit timestamp in host order.
	 **/
	inline uint32
	getRawTimestamp() const
	{ return ntohl(getHeader()->timestamp); };

	inline void
	setbuffer(const void* src, size_t len, size_t pos)
	{ memcpy(buffer + pos,src,len); }

	/// Packet sequence number in host order.
	uint16 cachedSeqNum;
	/// Packet timestamp in host order (includes initial shift).
	uint32 cachedTimestamp;

        /**
         * Offset into packet memory pointing to area for SRTP data.
         *
         * This offset points to the memory where the SRTP protect will
         * store the authentication and MKI data.
         */
        uint32 srtpDataOffset;

        /**
         * Lebgth of additional SRTP data.
         *
         * Covers the SRTP authentication and MKI data.
         */
        int32 srtpLength;

        /// total length, including header, payload and padding
        uint32 total;

        /// note: payload (not full packet) size.
        uint32 payloadSize;

private:
	/// packet in memory
	unsigned char* buffer;
	/// size of the header, including contributing sources and extensions
	uint32 hdrSize;
	/// whether the object was contructed with duplicated = true
	bool duplicated;

#ifdef	CCXX_PACKED
#pragma pack(1)
#endif
	/**
	 * @struct RTPFixedHeader
	 * @short RTP fixed header as it is send through the network.
	 *
	 * A low-level representation for generic RTP packet header as
	 * defined in RFC 1889. A packet consists of the fixed RTP
	 * header, a possibly empty list of contributing sources and
	 * the payload. Header contents are kept in network (big
	 * endian) order.
	 **/
	struct RTPFixedHeader
	{
#if	__BYTE_ORDER == __BIG_ENDIAN
		/// For big endian boxes
		unsigned char version:2;       ///< Version, currently 2
		unsigned char padding:1;       ///< Padding bit
		unsigned char extension:1;     ///< Extension bit
		unsigned char cc:4;            ///< CSRC count
		unsigned char marker:1;        ///< Marker bit
		unsigned char payload:7;       ///< Payload type
#else
		/// For little endian boxes
		unsigned char cc:4;            ///< CSRC count
		unsigned char extension:1;     ///< Extension bit
		unsigned char padding:1;       ///< Padding bit
		unsigned char version:2;       ///< Version, currently 2
		unsigned char payload:7;       ///< Payload type
		unsigned char marker:1;        ///< Marker bit
#endif
		uint16 sequence;        ///< sequence number
		uint32 timestamp;       ///< timestamp
		uint32 sources[1];      ///< contributing sources