libdatachannel/include/rtc/rtp.hpp

/**
 * Copyright (c) 2020 Staz Modrzynski
 * Copyright (c) 2020 Paul-Louis Ageneau
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef WEBRTC_SERVER_RTP_HPP
#define WEBRTC_SERVER_RTP_HPP

#include <cmath>
#include <netinet/in.h>

#ifndef htonll
#define htonll(x)                                                                                  \
	((uint64_t)htonl(((uint64_t)(x)&0xFFFFFFFF) << 32) | (uint64_t)htonl((uint64_t)(x) >> 32))
#endif
#ifndef ntohll
#define ntohll(x) htonll(x)
#endif

namespace rtc {
    typedef uint32_t SSRC;

#pragma pack(push, 1)

struct RTP {
private:
    uint8_t _first;
    uint8_t _payloadType;
    uint16_t _seqNumber;
    uint32_t _timestamp;
    SSRC _ssrc;

public:
    SSRC csrc[16];

    inline uint8_t version() const { return _first >> 6; }
    inline bool padding() const { return (_first >> 5) & 0x01; }
    inline uint8_t csrcCount() const { return _first & 0x0F; }
    inline uint8_t marker() const { return _payloadType & 0b10000000; }
    inline uint8_t payloadType() const { return _payloadType & 0b01111111; }
    inline uint16_t seqNumber() const { return ntohs(_seqNumber); }
    inline uint32_t timestamp() const { return ntohl(_timestamp); }
    inline uint32_t ssrc() const { return ntohl(_ssrc);}

    inline size_t getSize() const {
        return ((char*)&csrc) - ((char*)this) + sizeof(SSRC)*csrcCount();
    }

    char * getBody() const {
        return ((char*) &csrc) + sizeof(SSRC)*csrcCount();
    }

    inline void setSeqNumber(uint16_t newSeqNo) {
        _seqNumber = htons(newSeqNo);
    }
    inline void setPayloadType(uint8_t newPayloadType) {
        _payloadType = 0b01111111u & newPayloadType;
    }
    inline void setSsrc(uint32_t ssrc) {
        _ssrc = htonl(ssrc);
    }
};

struct RTCP_ReportBlock {
    SSRC ssrc;

private:
    uint32_t _fractionLostAndPacketsLost; // fraction lost is 8-bit, packets lost is 24-bit
    uint16_t _seqNoCycles;
    uint16_t _highestSeqNo;
    uint32_t _jitter;
    uint32_t _lastReport;
    uint32_t _delaySinceLastReport;

public:
    inline void preparePacket(SSRC ssrc, [[maybe_unused]] unsigned int packetsLost,
                              [[maybe_unused]] unsigned int totalPackets, uint16_t highestSeqNo,
                              uint16_t seqNoCycles, uint32_t jitter, uint64_t lastSR_NTP,
                              uint64_t lastSR_DELAY) {
        setSeqNo(highestSeqNo, seqNoCycles);
        setJitter(jitter);
        setSSRC(ssrc);

        // Middle 32 bits of NTP Timestamp
        //		  this->lastReport = lastSR_NTP >> 16u;
        setNTPOfSR(uint32_t(lastSR_NTP));
        setDelaySinceSR(uint32_t(lastSR_DELAY));

        // The delay, expressed in units of 1/65536 seconds
        //		  this->delaySinceLastReport = lastSR_DELAY;
    }

    inline void setSSRC(SSRC ssrc) { this->ssrc = htonl(ssrc); }
    inline SSRC getSSRC() const { return ntohl(ssrc); }

    inline void setPacketsLost([[maybe_unused]] unsigned int packetsLost,
                               [[maybe_unused]] unsigned int totalPackets) {
        // TODO Implement loss percentages.
        _fractionLostAndPacketsLost = 0;
    }
    inline unsigned int getLossPercentage() const {
        // TODO Implement loss percentages.
        return 0;
    }
    inline unsigned int getPacketLostCount() const {
        // TODO Implement total packets lost.
        return 0;
    }

    inline uint16_t seqNoCycles() const { return ntohs(_seqNoCycles); }
    inline uint16_t highestSeqNo() const { return ntohs(_highestSeqNo); }
    inline uint32_t jitter() const { return ntohl(_jitter); }

    inline void setSeqNo(uint16_t highestSeqNo, uint16_t seqNoCycles) {
        _highestSeqNo = htons(highestSeqNo);
        _seqNoCycles = htons(seqNoCycles);
    }

    inline void setJitter(uint32_t jitter) { _jitter = htonl(jitter); }

    inline void setNTPOfSR(uint64_t ntp) { _lastReport = htonll(ntp >> 16u); }
    inline uint32_t getNTPOfSR() const { return ntohl(_lastReport) << 16u; }

    inline void setDelaySinceSR(uint32_t sr) {
        // The delay, expressed in units of 1/65536 seconds
        _delaySinceLastReport = htonl(sr);
    }
    inline uint32_t getDelaySinceSR() const { return ntohl(_delaySinceLastReport); }

    inline void log() const {
        PLOG_DEBUG << "RTCP report block: "
                   << "ssrc="
                   << ntohl(ssrc)
                   // TODO: Implement these reports
                   //	<< ", fractionLost=" << fractionLost
                   //	<< ", packetsLost=" << packetsLost
                   << ", highestSeqNo=" << highestSeqNo() << ", seqNoCycles=" << seqNoCycles()
                   << ", jitter=" << jitter() << ", lastSR=" << getNTPOfSR()
                   << ", lastSRDelay=" << getDelaySinceSR();
    }
};

struct RTCP_HEADER {
private:
    uint8_t _first;
    uint8_t _payloadType;
    uint16_t _length;

public:
    inline uint8_t version() const { return _first >> 6; }
    inline bool padding() const { return (_first >> 5) & 0x01; }
    inline uint8_t reportCount() const { return _first & 0x0F; }
    inline uint8_t payloadType() const { return _payloadType; }
    inline uint16_t length() const { return ntohs(_length); }

    inline void setPayloadType(uint8_t type) { _payloadType = type; }
    inline void setReportCount(uint8_t count) { _first = (_first & 0b11100000) | (count & 0b00011111); }
    inline void setLength(uint16_t length) { _length = htons(length); }

    inline void prepareHeader(uint8_t payloadType, uint8_t reportCount, uint16_t length) {
        _first = 0b10000000; // version 2, no padding
        setReportCount(reportCount);
        setPayloadType(payloadType);
        setLength(length);
    }

    inline void log() const {
        PLOG_DEBUG << "RTCP header: "
                   << "version=" << unsigned(version()) << ", padding=" << padding()
                   << ", reportCount=" << unsigned(reportCount())
                   << ", payloadType=" << unsigned(payloadType()) << ", length=" << length();
    }
};

struct RTCP_FB_HEADER {
    RTCP_HEADER header;
    SSRC packetSender;
    SSRC mediaSource;

    [[nodiscard]] SSRC getPacketSenderSSRC() const {
        return ntohl(packetSender);
    }

    [[nodiscard]] SSRC getMediaSourceSSRC() const {
        return ntohl(mediaSource);
    }

    void setPacketSenderSSRC(SSRC ssrc) {
        this->packetSender = htonl(ssrc);
    }

    void setMediaSourceSSRC(SSRC ssrc) {
        this->mediaSource = htonl(ssrc);
    }

    void log() {
        header.log();
        PLOG_DEBUG << "FB: " << " packet sender: " << getPacketSenderSSRC() << " media source: " << getMediaSourceSSRC();
    }
};

struct RTCP_SR {
    RTCP_HEADER header;
    SSRC senderSSRC;

private:
    uint64_t _ntpTimestamp;
    uint32_t _rtpTimestamp;
    uint32_t _packetCount;
    uint32_t _octetCount;

    RTCP_ReportBlock _reportBlocks;

public:
    inline void preparePacket(SSRC senderSSRC, uint8_t reportCount) {
        unsigned int length =
                ((sizeof(header) + 24 + reportCount * sizeof(RTCP_ReportBlock)) / 4) - 1;
        header.prepareHeader(200, reportCount, uint16_t(length));
        this->senderSSRC = htonl(senderSSRC);
    }

    inline RTCP_ReportBlock *getReportBlock(int num) { return &_reportBlocks + num; }
    inline const RTCP_ReportBlock *getReportBlock(int num) const { return &_reportBlocks + num; }

    [[nodiscard]] inline size_t getSize() const {
        // "length" in packet is one less than the number of 32 bit words in the packet.
        return sizeof(uint32_t) * (1 + size_t(header.length()));
    }

    inline uint64_t ntpTimestamp() const { return ntohll(_ntpTimestamp); }
    inline uint32_t rtpTimestamp() const { return ntohl(_rtpTimestamp); }
    inline uint32_t packetCount() const { return ntohl(_packetCount); }
    inline uint32_t octetCount() const { return ntohl(_octetCount); }

    inline void setNtpTimestamp(uint32_t ts) { _ntpTimestamp = htonll(ts); }
    inline void setRtpTimestamp(uint32_t ts) { _rtpTimestamp = htonl(ts); }

    inline void log() const {
        header.log();
        PLOG_DEBUG << "RTCP SR: "
                   << " SSRC=" << ntohl(senderSSRC) << ", NTP_TS=" << ntpTimestamp()
                   << ", RTP_TS=" << rtpTimestamp() << ", packetCount=" << packetCount()
                   << ", octetCount=" << octetCount();

        for (unsigned i = 0; i < unsigned(header.reportCount()); i++) {
            getReportBlock(i)->log();
        }
    }
};

struct RTCP_RR {
    RTCP_HEADER header;
    SSRC senderSSRC;

private:
    RTCP_ReportBlock _reportBlocks;

public:
    inline RTCP_ReportBlock *getReportBlock(int num) { return &_reportBlocks + num; }
    inline const RTCP_ReportBlock *getReportBlock(int num) const { return &_reportBlocks + num; }

    inline SSRC getSenderSSRC() const { return ntohl(senderSSRC); }
    inline void setSenderSSRC(SSRC ssrc) { this->senderSSRC = htonl(ssrc); }

    [[nodiscard]] inline size_t getSize() const {
        // "length" in packet is one less than the number of 32 bit words in the packet.
        return sizeof(uint32_t) * (1 + size_t(header.length()));
    }

    inline void preparePacket(SSRC senderSSRC, uint8_t reportCount) {
        // "length" in packet is one less than the number of 32 bit words in the packet.
        size_t length = (sizeWithReportBlocks(reportCount) / 4) - 1;
        header.prepareHeader(201, reportCount, uint16_t(length));
        this->senderSSRC = htonl(senderSSRC);
    }

    inline static size_t sizeWithReportBlocks(uint8_t reportCount) {
        return sizeof(header) + 4 + size_t(reportCount) * sizeof(RTCP_ReportBlock);
    }

    inline void log() const {
        header.log();
        PLOG_DEBUG << "RTCP RR: "
                   << " SSRC=" << ntohl(senderSSRC);

        for (unsigned i = 0; i < unsigned(header.reportCount()); i++) {
            getReportBlock(i)->log();
        }
    }
};


struct RTCP_REMB {
    RTCP_FB_HEADER header;

    /*! \brief Unique identifier ('R' 'E' 'M' 'B') */
    char id[4];

    /*! \brief Num SSRC, Br Exp, Br Mantissa (bit mask) */
    uint32_t bitrate;

    SSRC ssrc[1];

    [[nodiscard]] unsigned int getSize() const {
        // "length" in packet is one less than the number of 32 bit words in the packet.
        return sizeof(uint32_t) * (1 + header.header.length());
    }

    void preparePacket(SSRC senderSSRC, unsigned int numSSRC, unsigned int bitrate) {

        // Report Count becomes the format here.
        header.header.prepareHeader(206, 15, 0);

        // Always zero.
        header.setMediaSourceSSRC(0);

        header.setPacketSenderSSRC(senderSSRC);

        id[0] = 'R';
        id[1] = 'E';
        id[2] = 'M';
        id[3] = 'B';

        setBitrate(numSSRC, bitrate);
    }

    void setBitrate(unsigned int numSSRC, unsigned int bitrate) {
        unsigned int exp = 0;
        while (bitrate > pow(2, 18) - 1) {
            exp++;
            bitrate /= 2;
        }

        // "length" in packet is one less than the number of 32 bit words in the packet.
        header.header.setLength((offsetof(RTCP_REMB, ssrc) / sizeof(uint32_t)) - 1 + numSSRC);

        this->bitrate = htonl(
                (numSSRC << (32u - 8u)) | (exp << (32u - 8u - 6u)) | bitrate
        );
    }

    void setSsrc(int iterator, SSRC newSssrc){
        ssrc[iterator] = htonl(newSssrc);
    }
    
    size_t static inline sizeWithSSRCs(int count) {
        return sizeof(RTCP_REMB) + (count-1)*sizeof(SSRC);
    }
};


struct RTCP_PLI {
    RTCP_FB_HEADER header;

    void preparePacket(SSRC messageSSRC) {
        header.header.prepareHeader(206, 1, 2);
        header.setPacketSenderSSRC(messageSSRC);
        header.setMediaSourceSSRC(messageSSRC);
    }

    void print() {
        header.log();
    }

    [[nodiscard]] static unsigned int size() {
        return sizeof(RTCP_FB_HEADER);
    }
};

struct RTCP_FIR_PART {
    uint32_t ssrc;
#if __BYTE_ORDER == __BIG_ENDIAN
    uint32_t seqNo: 8;
    uint32_t: 24;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
    uint32_t: 24;
    uint32_t seqNo: 8;
#endif
};

struct RTCP_FIR {
    RTCP_FB_HEADER header;
    RTCP_FIR_PART parts[1];

    void preparePacket(SSRC messageSSRC, uint8_t seqNo) {
        header.header.prepareHeader(206, 4, 2 + 2 * 1);
        header.setPacketSenderSSRC(messageSSRC);
        header.setMediaSourceSSRC(messageSSRC);
        parts[0].ssrc = htonl(messageSSRC);
        parts[0].seqNo = seqNo;
    }

    void print() {
        header.log();
    }

    [[nodiscard]] static unsigned int size() {
        return sizeof(RTCP_FB_HEADER) + sizeof(RTCP_FIR_PART);
    }
};

struct RTCP_NACK_PART {
    uint16_t pid;
    uint16_t blp;
};

class RTCP_NACK {
    RTCP_FB_HEADER header;
    RTCP_NACK_PART parts[1];
public:
    void preparePacket(SSRC ssrc, unsigned int discreteSeqNoCount) {
        header.header.prepareHeader(205, 1, 2 + discreteSeqNoCount);
        header.setMediaSourceSSRC(ssrc);
        header.setPacketSenderSSRC(ssrc);
    }

    /**
     * Add a packet to the list of missing packets.
     * @param fciCount The number of FCI fields that are present in this packet.
     *                  Let the number start at zero and let this function grow the number.
     * @param fciPID The seq no of the active FCI. It will be initialized automatically, and will change automatically.
     * @param missingPacket The seq no of the missing packet. This will be added to the queue.
     * @return true if the packet has grown, false otherwise.
     */
    bool addMissingPacket(unsigned int *fciCount, uint16_t *fciPID, const uint16_t &missingPacket) {
        if (*fciCount == 0 || missingPacket < *fciPID || missingPacket > (*fciPID + 16)) {
            parts[*fciCount].pid = htons(missingPacket);
            parts[*fciCount].blp = 0;
            *fciPID = missingPacket;
            (*fciCount)++;
            return true;
        } else {
            // TODO SPEEED!
            parts[(*fciCount) - 1].blp = htons(
                    ntohs(parts[(*fciCount) - 1].blp) | (1u << (unsigned int) (missingPacket - *fciPID)));
            return false;
        }
    }

    [[nodiscard]] static unsigned int getSize(unsigned int discreteSeqNoCount) {
        return offsetof(RTCP_NACK, parts) + sizeof(RTCP_NACK_PART) * discreteSeqNoCount;
    }
};

class RTP_RTX {
private:
    RTP header;
public:

    size_t copyTo(RTP *dest, size_t totalSize, uint8_t originalPayloadType) {
        memmove((char*)dest, (char*)this, header.getSize());
        dest->setSeqNumber(getOriginalSeqNo());
        dest->setPayloadType(originalPayloadType);
        memmove(dest->getBody(), getBody(), getBodySize(totalSize));
        return totalSize;
    }

    [[nodiscard]] uint16_t getOriginalSeqNo() const {
        return ntohs(*(uint16_t *) (header.getBody()));
    }

    char *getBody() {
        return header.getBody() + sizeof(uint16_t);
    }

    size_t getBodySize(size_t totalSize) {
        return totalSize - ((char *) getBody() - (char *) this);
    }

    RTP &getHeader() {
        return header;
    }

    size_t normalizePacket(size_t totalSize, SSRC originalSSRC, uint8_t originalPayloadType) {
        header.setSeqNumber(getOriginalSeqNo());
        header.setSsrc(originalSSRC); // TODO Endianess
        header.setPayloadType(originalPayloadType);
        // TODO, the -12 is the size of the header (which is variable!)
        memmove(header.getBody(), header.getBody() + sizeof(uint16_t), totalSize - 12 - sizeof(uint16_t));
        return totalSize - sizeof(uint16_t);
    }
};


#pragma pack(pop)
};
#endif //WEBRTC_SERVER_RTP_HPP