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RTMP.cpp
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RTMP.cpp
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// Copyright © 2021 Michael Thornburgh
// SPDX-License-Identifier: MIT
#include <cassert>
#include <cstring>
#include "RTMP.hpp"
#include "rtmfp/TCMessage.hpp"
namespace com { namespace zenomt { namespace rtmp {
static const size_t INITIAL_SEND_CHUNK_SIZE = 1024;
static const size_t MAX_TCMSG_LENGTH = (1<<24) - 1;
static const Time RTT_HISTORY_THRESH = 30.0;
static const size_t RTT_HISTORY_CAPACITY = 6;
static const size_t MIN_ACK_WINDOW = 1400 * 2;
static const size_t MAX_ACK_WINDOW = 1400 * 8;
static uint32_t _readu24(const uint8_t *cursor)
{
uint32_t rv = *cursor++;
rv <<= 8; rv += *cursor++;
rv <<= 8; rv += *cursor;
return rv;
}
static uint32_t _readu32(const uint8_t *cursor)
{
uint32_t rv = *cursor++;
rv <<= 8; rv += *cursor++;
rv <<= 8; rv += *cursor++;
rv <<= 8; rv += *cursor;
return rv;
}
static void _pushu24(RTMP::Bytes &dst, uint32_t val)
{
dst.push_back((val >> 16) & 0xff);
dst.push_back((val >> 8) & 0xff);
dst.push_back((val ) & 0xff);
}
static void _pushu32(RTMP::Bytes &dst, uint32_t val)
{
dst.push_back((val >> 24) & 0xff);
dst.push_back((val >> 16) & 0xff);
dst.push_back((val >> 8) & 0xff);
dst.push_back((val ) & 0xff);
}
static void _pushu32le(RTMP::Bytes &dst, uint32_t val)
{
dst.push_back((val ) & 0xff);
dst.push_back((val >> 8) & 0xff);
dst.push_back((val >> 16) & 0xff);
dst.push_back((val >> 24) & 0xff);
}
static void _setu32(uint8_t *dst, size_t val)
{
dst[0] = (val >> 24) & 0xff;
dst[1] = (val >> 16) & 0xff;
dst[2] = (val >> 8) & 0xff;
dst[3] = (val ) & 0xff;
}
static void _pushChunkBasicHeader(RTMP::Bytes &dst, uint8_t chunkType, int chunkStreamID)
{
if(chunkStreamID > 319)
{
int extendedChunkStreamID = chunkStreamID - 64;
dst.push_back(chunkType | 1);
// spec mismatch, Adobe sends little-endian, spec implies big-endian :(
dst.push_back((extendedChunkStreamID ) & 0xff);
dst.push_back((extendedChunkStreamID >> 8) & 0xff);
}
else if(chunkStreamID > 63)
{
int extendedChunkStreamID = chunkStreamID - 64;
dst.push_back(chunkType | 0);
dst.push_back(extendedChunkStreamID & 0xff);
}
else
dst.push_back(chunkType | (chunkStreamID & 0x3f));
}
struct RTMP::Message : public Object {
Message(uint32_t streamID, uint8_t messageType, uint32_t timestamp, const void *payload, size_t len, const std::shared_ptr<IssuerWriteReceipt> &receipt) :
m_streamID(streamID),
m_messageType(messageType),
m_timestamp(timestamp),
m_offset(0),
m_chunkStream(-1),
m_payload((const uint8_t *)payload, (const uint8_t *)payload + len),
m_receipt(receipt)
{}
uint32_t m_streamID;
uint8_t m_messageType;
uint32_t m_timestamp;
size_t m_offset;
int m_chunkStream;
Bytes m_payload;
std::shared_ptr<IssuerWriteReceipt> m_receipt;
};
// --- public methods
RTMP::RTMP(std::shared_ptr<IStreamPlatformAdapter> platform) :
m_platform(platform),
m_state(RT_UNKNOWN),
m_isServer(false),
m_simpleMode(false),
m_epoch(-INFINITY),
m_writeScheduled(false),
m_trimPending(false),
m_sendChunkSize(INITIAL_SEND_CHUNK_SIZE),
m_recvChunkSize(DEFAULT_CHUNK_SIZE),
m_sentBytes(0),
m_receivedBytes(0),
m_windowAckSize(MAX_ACK_WINDOW),
m_lastAckSent(0),
m_lastAckReceived(0),
m_ackedBytes(0),
m_peerBandwidth(SIZE_MAX),
m_lastPeerBandwidthType(TC_SET_PEER_BW_LIMIT_SOFT),
m_peerBandwidthAckSize(MAX_ACK_WINDOW),
m_lastAckWinSent(0),
m_isPaused(false),
m_rttAckSize(MIN_ACK_WINDOW)
{
}
RTMP::~RTMP()
{
m_platform->setOnReceiveBytesCallback(nullptr);
m_platform->setOnStreamDidCloseCallback(nullptr);
}
bool RTMP::init(bool isServer)
{
if(m_state > RT_UNKNOWN)
return false;
m_epoch = getCurrentTime();
m_isServer = isServer;
m_state = RT_UNINITIALIZED;
if(not isServer)
queueHandshake01();
m_platform->setOnReceiveBytesCallback([this] (const void *bytes, size_t len) { return onReceiveBytes(bytes, len); });
m_platform->setOnStreamDidCloseCallback([this] { onInterfaceDidClose(); });
return true;
}
void RTMP::setChunkSize(size_t newSize)
{
if(m_state > RT_OPEN)
return; // sorry, too late!
if(newSize < DEFAULT_CHUNK_SIZE)
newSize = DEFAULT_CHUNK_SIZE;
if(newSize > (size_t)(INT32_MAX))
newSize = INT32_MAX; // §5.4.1
if(newSize != m_sendChunkSize)
{
m_sendChunkSize = newSize;
if(RT_OPEN == m_state)
queueSetChunkSize(); // this can wait to go until the next time we actually need to write something
}
}
size_t RTMP::getChunkSize() const
{
return m_sendChunkSize;
}
std::shared_ptr<WriteReceipt> RTMP::write(Priority pri, uint32_t streamID, uint8_t messageType, uint32_t timestamp, const void *payload, size_t len, Time startWithin, Time finishWithin)
{
if((m_state >= RT_CLOSING) or (len > MAX_TCMSG_LENGTH))
return nullptr;
switch(messageType)
{
case TCMSG_SET_CHUNK_SIZE:
case TCMSG_ABORT_MESSAGE:
case TCMSG_ACKNOWLEDGEMENT:
case TCMSG_WINDOW_ACK_SIZE:
case TCMSG_SET_PEER_BW:
// not allowed to write protocol control messages directly
return nullptr;
}
auto receipt = share_ref(new IssuerWriteReceipt(getCurrentTime(), startWithin, finishWithin), false);
auto message = share_ref(new Message(streamID, messageType, timestamp, payload, len, receipt), false);
receipt->useCountUp();
m_sendQueues[pri].append(message);
if(RT_OPEN == m_state)
scheduleWrite();
scheduleTrimSendQueues();
return receipt;
}
std::shared_ptr<WriteReceipt> RTMP::write(Priority pri, uint32_t streamID, uint8_t messageType, uint32_t timestamp, const Bytes &payload, Time startWithin, Time finishWithin)
{
return write(pri, streamID, messageType, timestamp, payload.data(), payload.size(), startWithin, finishWithin);
}
Time RTMP::getUnsentAge(Priority pri_) const
{
Time now = getCurrentTime();
Time rv = 0.0;
for(int pri = pri_; pri < NUM_PRIORITIES; pri++)
{
auto &q = m_sendQueues[pri];
if(not q.empty())
rv = std::max(rv, now - q.firstValue()->m_receipt->createdAt());
}
return rv;
}
Time RTMP::getInstanceAge() const
{
return getCurrentTime() - m_epoch;
}
Time RTMP::getCurrentTime() const
{
return m_platform->getCurrentTime();
}
uint32_t RTMP::timeAsTimestamp(Time t) const
{
return ((uintmax_t)(t * 1000.0)) & UINT32_MAX;
}
void RTMP::close()
{
clearCallbacks();
if(RT_OPEN == m_state)
{
m_state = RT_CLOSING;
scheduleWrite();
}
else if(RT_CLOSING == m_state)
; // already here
else
setClosedState();
}
void RTMP::setSimpleMode(bool isSimple)
{
m_simpleMode = isSimple;
}
void RTMP::setPaused(bool isPaused)
{
if(m_isPaused and not isPaused) // resuming, kick processing
m_platform->doLater([this] { onReceiveBytes(nullptr, 0); });
m_isPaused = isPaused;
}
Time RTMP::getRTT() const
{
return m_smoothedRTT;
}
Time RTMP::getBaseRTT() const
{
return m_baseRTTCache;
}
size_t RTMP::getBytesInFlight() const
{
return m_sentBytes - m_ackedBytes;
}
bool RTMP::onReceiveBytes(const void *bytes_, size_t len)
{
if((RT_UNKNOWN == m_state) or (RT_PROTOCOL_ERROR == m_state))
{
setClosedState();
return true;
}
m_receivedBytes += len;
// TODO there's an opportunity to avoid a copy when the input buffer is empty
const uint8_t *bytes = (const uint8_t *)bytes_;
m_inputBuffer.insert(m_inputBuffer.end(), bytes, bytes + len);
const uint8_t *buffer = m_inputBuffer.data();
const uint8_t *limit = buffer + m_inputBuffer.size();
const uint8_t *cursor = buffer;
while(cursor < limit)
{
if(m_isPaused)
break;
long consumed = onInput(cursor, limit);
if(consumed < 0)
{
setClosedState();
return true;
}
if(0 == consumed)
break;
cursor += consumed;
}
sendAckIfNeeded();
shiftInputBuffer(cursor - buffer);
return true;
}
void RTMP::onInterfaceDidClose()
{
setClosedState();
}
// ---
bool RTMP::writeRawOutputBuffer()
{
if((not m_rawOutputBuffer.empty()) and (m_state < RT_PROTOCOL_ERROR))
{
m_platform->writeBytes(m_rawOutputBuffer.data(), m_rawOutputBuffer.size());
m_sentBytes += m_rawOutputBuffer.size();
m_rawOutputBuffer.clear();
if(RT_OPEN == m_state)
startRTT();
return true;
}
return false;
}
size_t RTMP::queueStartChunk(int chunkStreamID, uint32_t streamID, uint8_t type_, uint32_t timestamp, const uint8_t *payload, size_t len)
{
assert(chunkStreamID >= 2);
assert(chunkStreamID < NUM_CHUNKSTREAMS);
uint8_t chunkType = CHUNK_TYPE_0; // default
auto &cs = m_sendChunkStreams[chunkStreamID];
if(cs.m_initted and (timestamp - cs.m_timestamp <= (uint32_t)(INT32_MAX)) and not m_simpleMode)
{
// maybe we can use a more compact chunk type
if(streamID == cs.m_streamID)
{
chunkType = CHUNK_TYPE_1;
if((type_ == cs.m_type) and (len == cs.m_length))
{
chunkType = CHUNK_TYPE_2;
if(cs.m_timestampDeltaValid and (timestamp == cs.m_timestamp + cs.m_timestampDelta))
chunkType = CHUNK_TYPE_3;
}
}
}
uint32_t effectiveTimestamp = (CHUNK_TYPE_0 == chunkType) ? timestamp : timestamp - cs.m_timestamp;
uint32_t extendedTimestamp = (effectiveTimestamp >= UINT32_C(0xffffff)) ? effectiveTimestamp : 0;
uint32_t timestampField = extendedTimestamp ? UINT32_C(0xffffff) : effectiveTimestamp;
cs.m_streamID = streamID;
cs.m_timestamp = timestamp;
cs.m_timestampDelta = effectiveTimestamp;
cs.m_length = len;
cs.m_type = type_;
cs.m_initted = true;
cs.m_lastUsed = getCurrentTime();
cs.m_timestampDeltaValid = CHUNK_TYPE_0 != chunkType;
_pushChunkBasicHeader(m_rawOutputBuffer, chunkType, chunkStreamID);
switch(chunkType)
{
case CHUNK_TYPE_0:
_pushu24(m_rawOutputBuffer, timestampField);
_pushu24(m_rawOutputBuffer, len);
m_rawOutputBuffer.push_back(type_);
_pushu32le(m_rawOutputBuffer, streamID);
break;
case CHUNK_TYPE_1:
_pushu24(m_rawOutputBuffer, timestampField);
_pushu24(m_rawOutputBuffer, len);
m_rawOutputBuffer.push_back(type_);
break;
case CHUNK_TYPE_2:
_pushu24(m_rawOutputBuffer, timestampField);
break;
case CHUNK_TYPE_3:
break;
}
if(extendedTimestamp)
_pushu32(m_rawOutputBuffer, extendedTimestamp);
size_t writeAmount = std::min(len, m_sendChunkSize);
m_rawOutputBuffer.insert(m_rawOutputBuffer.end(), payload, payload + writeAmount);
cs.m_busy = writeAmount < len;
return writeAmount;
}
size_t RTMP::queueNextChunk(int chunkStreamID, const uint8_t *payload, size_t cursor)
{
assert(chunkStreamID >= 2);
assert(chunkStreamID < NUM_CHUNKSTREAMS);
auto &cs = m_sendChunkStreams[chunkStreamID];
assert(cs.m_busy);
_pushChunkBasicHeader(m_rawOutputBuffer, CHUNK_TYPE_3, chunkStreamID);
uint32_t maybeExtendedTimestamp = cs.m_timestampDelta;
if(maybeExtendedTimestamp >= UINT32_C(0xffffff))
_pushu32(m_rawOutputBuffer, maybeExtendedTimestamp);
size_t writeAmount = std::min(cs.m_length - cursor, m_sendChunkSize);
m_rawOutputBuffer.insert(m_rawOutputBuffer.end(), payload + cursor, payload + cursor + writeAmount);
cs.m_busy = cursor + writeAmount < cs.m_length;
return writeAmount;
}
void RTMP::queueControlMessage(uint8_t type_, const uint8_t *payload, size_t len)
{
queueStartChunk(CONTROL_CHUNKSTREAM_ID, 0, type_, 0, payload, len);
}
void RTMP::queueSetChunkSize()
{
uint8_t buf[4];
_setu32(buf, m_sendChunkSize & UINT32_C(0x7fffffff));
queueControlMessage(TCMSG_SET_CHUNK_SIZE, buf, sizeof(buf));
}
void RTMP::queueAbortMessage(int chunkStreamID)
{
uint8_t buf[4];
_setu32(buf, chunkStreamID & UINT32_C(0xffffff));
queueControlMessage(TCMSG_ABORT_MESSAGE, buf, sizeof(buf));
}
void RTMP::queueAck()
{
uint8_t buf[4];
_setu32(buf, m_receivedBytes);
queueControlMessage(TCMSG_ACKNOWLEDGEMENT, buf, sizeof(buf));
}
void RTMP::sendAck()
{
if(m_state >= RT_OPEN)
{
queueAck();
m_lastAckSent = m_receivedBytes;
scheduleWrite();
}
}
void RTMP::sendAckIfNeeded()
{
if(m_lastAckSent + m_windowAckSize <= m_receivedBytes)
sendAck();
}
void RTMP::queueWindowAckSize(uint32_t newSize)
{
uint8_t buf[4];
_setu32(buf, newSize);
queueControlMessage(TCMSG_WINDOW_ACK_SIZE, buf, sizeof(buf));
}
void RTMP::refreshWindowAckSize()
{
uint32_t newSize = std::min(m_rttAckSize, m_peerBandwidthAckSize);
if(newSize != m_lastAckWinSent)
{
queueWindowAckSize(newSize);
m_lastAckWinSent = newSize;
}
}
bool RTMP::trimSendQueues(bool abandonAll)
{
Time now = getCurrentTime();
bool anyPartial = false;
for(int pri = PRI_HIGHEST; pri >= PRI_LOWEST; pri--)
{
auto &q = m_sendQueues[pri];
while(not q.empty())
{
auto &first = q.firstValue();
if(abandonAll)
first->m_receipt->abandon();
else
first->m_receipt->abandonIfNeeded(now);
if(not first->m_receipt->isAbandoned())
break;
if(first->m_offset and m_sendChunkStreams[first->m_chunkStream].m_busy)
{
queueAbortMessage(first->m_chunkStream);
m_sendChunkStreams[first->m_chunkStream].m_busy = false;
anyPartial = true;
}
first->m_receipt->useCountDown();
q.removeFirst();
}
}
return anyPartial;
}
void RTMP::scheduleTrimSendQueues()
{
if(not m_trimPending)
{
m_trimPending = true;
m_platform->doLater([this] {
m_trimPending = false;
if(m_state < RT_PROTOCOL_ERROR)
trimSendQueues(false);
});
}
}
void RTMP::scheduleWrite()
{
if((not m_writeScheduled) and (m_state < RT_PROTOCOL_ERROR))
{
m_platform->notifyWhenWritable([this] { return onWritable(); });
m_writeScheduled = true;
}
}
bool RTMP::onWritable()
{
if(writeRawOutputBuffer())
return true;
if(checkFlowControlWritable())
{
if(trimSendQueues(false) and writeRawOutputBuffer())
return true;
for(int pri = PRI_HIGHEST; pri >= PRI_LOWEST; pri--)
{
auto &q = m_sendQueues[pri];
if(not q.empty())
{
auto &first = q.firstValue();
if(first->m_chunkStream < 0)
{
first->m_chunkStream = findChunkStream(first->m_streamID, first->m_messageType, first->m_payload.size());
first->m_offset = queueStartChunk(first->m_chunkStream, first->m_streamID, first->m_messageType, first->m_timestamp, first->m_payload.data(), first->m_payload.size());
first->m_receipt->start();
}
else
first->m_offset += queueNextChunk(first->m_chunkStream, first->m_payload.data(), first->m_offset);
if(not m_sendChunkStreams[first->m_chunkStream].m_busy)
{
first->m_receipt->useCountDown();
q.removeFirst();
}
writeRawOutputBuffer();
return true;
}
}
// if we get here then we're completely flushed
if(RT_CLOSING == m_state)
setClosedState();
}
m_writeScheduled = false;
return false;
}
int RTMP::findChunkStream(uint32_t streamID, uint8_t type_, size_t len) const
{
// per §6.2 ¶2 TCMSG_USER_CONTROL messages SHOULD be sent on chunk stream 2.
// however, they should also be queued normally and subject to queue precedence
// so they go out in the right order.
if((0 == streamID) and (TCMSG_USER_CONTROL == type_) and (len <= m_sendChunkSize) and not m_sendChunkStreams[CONTROL_CHUNKSTREAM_ID].m_busy)
return CONTROL_CHUNKSTREAM_ID; // this chunk stream should never be marked busy
int bestSoFar = -1;
for(int i = CONTROL_CHUNKSTREAM_ID + 1; i < NUM_CHUNKSTREAMS; i++)
{
auto &cs = m_sendChunkStreams[i];
if(not cs.m_initted)
return i;
if(cs.m_busy)
continue;
if(bestSoFar < 0)
bestSoFar = i;
if((streamID == cs.m_streamID) and (type_ == cs.m_type))
return i;
if(cs.m_streamID == streamID)
{
if(m_sendChunkStreams[bestSoFar].m_streamID != streamID)
bestSoFar = i;
if(cs.m_lastUsed < m_sendChunkStreams[bestSoFar].m_lastUsed)
bestSoFar = i;
}
else if((m_sendChunkStreams[bestSoFar].m_streamID != streamID) and (cs.m_lastUsed < m_sendChunkStreams[bestSoFar].m_lastUsed))
bestSoFar = i;
}
assert(bestSoFar > 0);
return bestSoFar;
}
bool RTMP::checkFlowControlWritable() const
{
uint32_t outstanding = getBytesInFlight();
return (outstanding < m_peerBandwidth) and (outstanding < outstandingThresh) and ((RT_OPEN == m_state) or (RT_CLOSING == m_state));
}
bool RTMP::onSetChunkSizeControlMessage(const uint8_t *payload, size_t len)
{
if(len < 4)
return false;
uint32_t newChunkSize = _readu32(payload);
if((0 == newChunkSize) or (newChunkSize > UINT32_C(0x7fffffff)))
return false;
m_recvChunkSize = newChunkSize;
return true;
}
bool RTMP::onAbortMessageControlMessage(const uint8_t *payload, size_t len)
{
if(len < 4)
return false;
uint32_t chunkStreamID = _readu32(payload);
if((chunkStreamID < 2) or (chunkStreamID > 65535 + 64))
return false;
auto &cs = m_recvChunkStreams[chunkStreamID];
if(not cs.m_initted)
return false;
cs.m_payload.clear();
return true;
}
bool RTMP::onAckControlMessage(const uint8_t *payload, size_t len)
{
if(len < 4)
return false;
uint32_t ack = _readu32(payload);
m_ackedBytes += uint32_t(ack - m_lastAckReceived);
m_lastAckReceived = ack;
measureRTT();
scheduleWrite();
return true;
}
bool RTMP::onWindowAckSizeControlMessage(const uint8_t *payload, size_t len)
{
if(len < 4)
return false;
m_windowAckSize = std::max(_readu32(payload), uint32_t(1));
sendAck();
return true;
}
bool RTMP::onSetPeerBandwidthControlMessage(const uint8_t *payload, size_t len)
{
if(len < 5)
return false;
uint32_t newPeerBandwidth = _readu32(payload);
uint8_t limitType = payload[4];
if(TC_SET_PEER_BW_LIMIT_DYNAMIC == limitType)
{
if(TC_SET_PEER_BW_LIMIT_HARD != m_lastPeerBandwidthType)
return true;
limitType = TC_SET_PEER_BW_LIMIT_HARD;
}
m_lastPeerBandwidthType = limitType;
m_peerBandwidthAckSize = std::max(newPeerBandwidth / 2, UINT32_C(2));
refreshWindowAckSize();
if((TC_SET_PEER_BW_LIMIT_HARD == limitType) or (newPeerBandwidth < m_peerBandwidth))
m_peerBandwidth = newPeerBandwidth;
return true;
}
bool RTMP::onControlMessage(uint8_t messageType, const uint8_t *payload, size_t len)
{
switch(messageType)
{
case TCMSG_SET_CHUNK_SIZE:
return onSetChunkSizeControlMessage(payload, len);
case TCMSG_ABORT_MESSAGE:
return onAbortMessageControlMessage(payload, len);
case TCMSG_ACKNOWLEDGEMENT:
return onAckControlMessage(payload, len);
case TCMSG_WINDOW_ACK_SIZE:
return onWindowAckSizeControlMessage(payload, len);
case TCMSG_SET_PEER_BW:
return onSetPeerBandwidthControlMessage(payload, len);
default:
break;
}
return true;
}
void RTMP::onUserMessage(uint32_t streamID, uint8_t messageType, uint32_t timestamp, const uint8_t *payload, size_t len)
{
if(onmessage and (m_state < RT_CLOSING))
onmessage(streamID, messageType, timestamp, payload, len);
}
bool RTMP::onMessageCompleted(uint32_t streamID, uint8_t messageType, uint32_t timestamp, const uint8_t *payload, size_t len)
{
switch(messageType)
{
case TCMSG_SET_CHUNK_SIZE:
case TCMSG_ABORT_MESSAGE:
case TCMSG_ACKNOWLEDGEMENT:
case TCMSG_WINDOW_ACK_SIZE:
case TCMSG_SET_PEER_BW:
if(0 != streamID)
return false;
return onControlMessage(messageType, payload, len);
case TCMSG_AGGREGATE:
break; // TODO handle these if configured
default:
break;
}
onUserMessage(streamID, messageType, timestamp, payload, len);
return true;
}
void RTMP::queueHandshake01()
{
m_rawOutputBuffer.push_back(RTMP_VERSION);
uint32_t timestamp = timeAsTimestamp(getInstanceAge());
_pushu32(m_rawOutputBuffer, timestamp);
_pushu32(m_rawOutputBuffer, 0);
m_rawOutputBuffer.insert(m_rawOutputBuffer.end(), 1536 - 8, m_isServer ? 'S' : 'C');
scheduleWrite();
}
void RTMP::queueHandshake2(const uint8_t *handshake1)
{
m_rawOutputBuffer.insert(m_rawOutputBuffer.end(), handshake1, handshake1 + 4);
_pushu32(m_rawOutputBuffer, timeAsTimestamp(getInstanceAge()));
m_rawOutputBuffer.insert(m_rawOutputBuffer.end(), handshake1 + 8, handshake1 + 1536);
scheduleWrite();
}
void RTMP::shiftInputBuffer(size_t amount)
{
if(amount)
{
assert(amount <= m_inputBuffer.size());
size_t newSize = m_inputBuffer.size() - amount;
uint8_t *buf = m_inputBuffer.data();
::memmove(buf, buf + amount, newSize);
m_inputBuffer.resize(newSize);
}
}
long RTMP::onOpenInput(const uint8_t *bytes, const uint8_t *limit, size_t remaining)
{
const uint8_t *cursor = bytes;
uint8_t chunkType = *cursor & CHUNK_TYPE_MASK;
uint8_t maybeChunkStreamID = *cursor & CHUNK_STREAM_ID_MASK;
size_t needed = 1;
cursor++;
if(maybeChunkStreamID < 2)
needed++;
if(1 == maybeChunkStreamID)
needed++;
switch(chunkType)
{
case CHUNK_TYPE_0: needed += 11; break;
case CHUNK_TYPE_1: needed += 7; break;
case CHUNK_TYPE_2: needed += 3; break;
default: break;
}
if(remaining < needed)
return 0;
uint32_t chunkStreamID;
if(0 == maybeChunkStreamID)
chunkStreamID = *cursor++ + 64;
else if(1 == maybeChunkStreamID)
{
// spec mismatch, Adobe sends little-endian, spec implies big-endian :(
chunkStreamID = cursor[0] + (cursor[1] << 8) + 64;
cursor += 2;
}
else
chunkStreamID = maybeChunkStreamID;
auto &cs = m_recvChunkStreams[chunkStreamID];
if((not cs.m_initted) and (CHUNK_TYPE_0 != chunkType))
return -1;
uint32_t timestamp;
if(chunkType < CHUNK_TYPE_3)
{
timestamp = _readu24(cursor);
cursor += 3;
}
else
timestamp = cs.m_timestampDelta;
uint32_t messageLength;
uint8_t messageTypeID;
if(chunkType < CHUNK_TYPE_2)
{
messageLength = _readu24(cursor);
cursor += 3;
messageTypeID = *cursor++;
}
else
{
messageLength = cs.m_length;
messageTypeID = cs.m_type;
}
size_t messageLengthRemaining = messageLength;
if(CHUNK_TYPE_3 == chunkType)
messageLengthRemaining -= cs.m_payload.size();
size_t chunkPayloadLength = std::min(m_recvChunkSize, messageLengthRemaining);
needed += chunkPayloadLength;
if(remaining < needed)
return 0;
uint32_t streamID;
if(chunkType < CHUNK_TYPE_1)
{
// ugh, little endian for some reason
streamID = *cursor++;
streamID += (*cursor++ << 8);
streamID += (*cursor++ << 16);
streamID += (*cursor++ << 24);
}
else
streamID = cs.m_streamID;
if(timestamp >= UINT32_C(0xffffff))
{
needed += 4;
if(remaining < needed)
return 0;
timestamp = _readu32(cursor); cursor += 4;
}
switch(chunkType)
{
case CHUNK_TYPE_0:
cs.m_streamID = streamID;
cs.m_timestamp = timestamp;
cs.m_timestampDelta = timestamp;
cs.m_length = messageLength;
cs.m_type = messageTypeID;
cs.m_payload.clear();
cs.m_initted = true;
break;
case CHUNK_TYPE_1:
cs.m_timestampDelta = timestamp;
cs.m_timestamp += timestamp;
cs.m_length = messageLength;
cs.m_type = messageTypeID;
cs.m_payload.clear();
break;
case CHUNK_TYPE_2:
cs.m_timestampDelta = timestamp;
cs.m_timestamp += timestamp;
cs.m_payload.clear();
break;
case CHUNK_TYPE_3:
cs.m_timestampDelta = timestamp;
if(0 == cs.m_payload.size())
cs.m_timestamp += timestamp;
break;
}
assert(cursor + chunkPayloadLength <= limit);
cs.m_payload.insert(cs.m_payload.end(), cursor, cursor + chunkPayloadLength);
cursor += chunkPayloadLength;
assert((size_t)(cursor - bytes) == (size_t)needed);
assert(cs.m_payload.size() <= cs.m_length);
if(cs.m_payload.size() == cs.m_length)
{
if(not onMessageCompleted(cs.m_streamID, cs.m_type, cs.m_timestamp, cs.m_payload.data(), cs.m_payload.size()))
return -1;
cs.m_payload.clear();
}
return needed;
}
long RTMP::onUninitializedInput(const uint8_t *bytes)
{
if(*bytes < RTMP_VERSION)
return -1;
if(*bytes >= 32) // not RTMP
return -1;
if(m_isServer)
queueHandshake01();
m_state = RT_VERSION_SENT;
return 1;
}
long RTMP::onVersionSentInput(const uint8_t *bytes, size_t remaining)
{
if(remaining < 1536)
return 0;
queueHandshake2(bytes);
m_state = RT_ACK_SENT;
return 1536;
}
long RTMP::onAckSentInput(const uint8_t *, size_t remaining)
{
if(remaining < 1536)
return 0;
// TODO: use time timestamps in the echo message to... do something i guess, like make an
// initial RTT measurement (though really the flight time of the echo should be used instead).