From a1b68fb8ed6c2589dd13bd9ba1fab7050ba38226 Mon Sep 17 00:00:00 2001 From: Andrew Meadows Date: Wed, 27 May 2026 10:18:29 -0700 Subject: Drop fewer packets on UDP packet flood (#5565) * ACK received-but-unprocessed packets when queued * Prioritize packets between high- and low-priority (high-priority are: reliable packets that need an ACK) * Increase max size of LLPacketRing buffer --- indra/llmessage/message.cpp | 315 ++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 291 insertions(+), 24 deletions(-) (limited to 'indra/llmessage/message.cpp') diff --git a/indra/llmessage/message.cpp b/indra/llmessage/message.cpp index e2937490ba..b11e4598e7 100644 --- a/indra/llmessage/message.cpp +++ b/indra/llmessage/message.cpp @@ -78,6 +78,8 @@ #include "lltransfertargetvfile.h" #include "llcorehttputil.h" #include "llpounceable.h" +#include "llproxy.h" +#include "llrand.h" // Constants //const char* MESSAGE_LOG_FILENAME = "message.log"; @@ -173,7 +175,7 @@ void LLMessageSystem::init() mTotalBytesIn = 0; mTotalBytesOut = 0; - mDroppedPackets = 0; // total dropped packets in + mLostPackets = 0; // total lost packets out mResentPackets = 0; // total resent packets out mFailedResendPackets = 0; // total resend failure packets out mOffCircuitPackets = 0; // total # of off-circuit packets rejected @@ -184,6 +186,13 @@ void LLMessageSystem::init() mIncomingCompressedSize = 0; mCurrentRecvPacketID = 0; + mActualBytesIn = 0; + mActualBytesOut = 0; + mDropPercentage = 0.0f; + mPacketsToDrop = 0; + mNumDroppedPackets = 0; + mNumDroppedPacketsTotal = 0; + mMessageFileVersionNumber = 0.f; mTimingCallback = NULL; @@ -508,18 +517,16 @@ bool LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count ) bool recv_reliable = false; bool recv_resent = false; - S32 acks = 0; + S32 num_acks = 0; S32 true_rcv_size = 0; U8* buffer = mTrueReceiveBuffer; - mTrueReceiveSize = mPacketRing.receivePacket(mSocket, (char *)mTrueReceiveBuffer); + mTrueReceiveSize = receivePacketOrDrop((char *)mTrueReceiveBuffer); // If you want to dump all received packets into SecondLife.log, uncomment this //dumpPacketToLog(); receive_size = mTrueReceiveSize; - mLastSender = mPacketRing.getLastSender(); - mLastReceivingIF = mPacketRing.getLastReceivingInterface(); if (receive_size < (S32) LL_MINIMUM_VALID_PACKET_SIZE) { @@ -535,24 +542,23 @@ bool LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count ) } else { - LLHost host; - LLCircuitData* cdp; - - // note if packet acks are appended. + // handle any packet ACKs (for outbound messages) found at tail of inbound message if(buffer[0] & LL_ACK_FLAG) { - acks += buffer[--receive_size]; + // Note: these ACKs may have already been handled if this was a buffered message + // but it doesn't hurt to handle them again. + num_acks += buffer[--receive_size]; true_rcv_size = receive_size; - if(receive_size >= ((S32)(acks * sizeof(TPACKETID) + LL_MINIMUM_VALID_PACKET_SIZE))) + if(receive_size >= ((S32)(num_acks * sizeof(TPACKETID) + LL_MINIMUM_VALID_PACKET_SIZE))) { - receive_size -= acks * sizeof(TPACKETID); + receive_size -= num_acks * sizeof(TPACKETID); } else { // mal-formed packet. ignore it and continue with // the next one LL_WARNS("Messaging") << "Malformed packet received. Packet size " - << receive_size << " with invalid no. of acks " << acks + << receive_size << " with invalid no. of acks " << num_acks << LL_ENDL; valid_packet = false; continue; @@ -562,20 +568,20 @@ bool LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count ) // process the message as normal mIncomingCompressedSize = zeroCodeExpand(&buffer, &receive_size); mCurrentRecvPacketID = ntohl(*((U32*)(&buffer[1]))); - host = getSender(); + LLHost host = getSender(); const bool resetPacketId = true; - cdp = findCircuit(host, resetPacketId); + LLCircuitData* cdp = findCircuit(host, resetPacketId); // At this point, cdp is now a pointer to the circuit that // this message came in on if it's valid, and NULL if the // circuit was bogus. - if(cdp && (acks > 0) && ((S32)(acks * sizeof(TPACKETID)) < (true_rcv_size))) + if(cdp && (num_acks > 0) && ((S32)(num_acks * sizeof(TPACKETID)) < (true_rcv_size))) { TPACKETID packet_id; U32 mem_id=0; - for(S32 i = 0; i < acks; ++i) + for(S32 i = 0; i < num_acks; ++i) { true_rcv_size -= sizeof(TPACKETID); memcpy(&mem_id, &mTrueReceiveBuffer[true_rcv_size], /* Flawfinder: ignore*/ @@ -630,7 +636,7 @@ bool LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count ) str << tbuf << "(unknown)" << (recv_reliable ? " reliable" : "") << " resent " - << ((acks > 0) ? "acks" : "") + << ((num_acks > 0) ? "acks" : "") << " DISCARD DUPLICATE"; LL_INFOS("Messaging") << str.str() << LL_ENDL; } @@ -680,7 +686,7 @@ bool LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count ) if ( valid_packet ) { - logValidMsg(cdp, host, recv_reliable, recv_resent, acks>0 ); + logValidMsg(cdp, host, recv_reliable, recv_resent, num_acks>0 ); valid_packet = mTemplateMessageReader->readMessage(buffer, host); } @@ -724,7 +730,7 @@ bool LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count ) // Check to see if we need to print debug info if ((mt_sec - mCircuitPrintTime) > mCircuitPrintFreq) { - mPacketRing.dumpPacketRingStats(); + dumpPacketRingStats(); dumpCircuitInfo(); mCircuitPrintTime = mt_sec; } @@ -749,6 +755,10 @@ S32 LLMessageSystem::getReceiveBytes() const } } +F32 LLMessageSystem::getBufferLoadRate() const +{ + return llmax(mHighPriorityInbound.getBufferLoadRate(), mLowPriorityInbound.getBufferLoadRate()); +} void LLMessageSystem::processAcks(LockMessageChecker&, F32 collect_time) { @@ -822,7 +832,264 @@ void LLMessageSystem::processAcks(LockMessageChecker&, F32 collect_time) S32 LLMessageSystem::drainUdpSocket() { - return mPacketRing.drainSocket(mSocket); + S32 packet_size = 1; + S32 num_loops = 0; + S32 old_num_buffered_packets = getNumBufferedPackets(); + while (packet_size > 0) + { + packet_size = bufferInboundPacket(); + ++num_loops; + } + S32 num_dropped_packets = (num_loops - 1 + old_num_buffered_packets) - getNumBufferedPackets(); + if (num_dropped_packets > 0) + { + mNumDroppedPackets += num_dropped_packets; + } + return getNumBufferedPackets(); +} + +bool LLMessageSystem::computeDrop() +{ + bool drop = (mDropPercentage > 0.0f && (ll_frand(100.f) < mDropPercentage)); + if (drop) + { + ++mPacketsToDrop; + } + if (mPacketsToDrop > 0) + { + --mPacketsToDrop; + drop = true; + } + return drop; +} + +bool LLMessageSystem::isHighPriorityMessage(const LLPacketBuffer& pkt) const +{ + S32 size = pkt.getSize(); + if (size < LL_PACKET_ID_SIZE + 1) + { + return false; + } + + // We want to prioritize crucial messages use to establish viewer <--> simulator connection, + // which are all low-frequency. A simple approximation is to just prioritize all non high- + // frequency messages. + // + // High frequency messages use a single byte for message_id whereas all low- and medium- + // frequency messages have 255 at the first byte of the message_id (which is after the + // LL_PACKET_ID_SIZE bytes of packet_id). + return *((const U8*)pkt.getData() + LL_PACKET_ID_SIZE) == 255; +} + +void LLMessageSystem::dropPackets(U32 num_to_drop) +{ + mPacketsToDrop += num_to_drop; +} + +void LLMessageSystem::setDropPercentage(F32 percent_to_drop) +{ + mDropPercentage = percent_to_drop; +} + +S32 LLMessageSystem::receivePacketOrDrop(char* datap) +{ + if (getNumBufferedPackets() > 0) + { + LLHost invalid_host; + LLPacketBuffer pkt(invalid_host, nullptr, 0); + if (!mHighPriorityInbound.popPacket(pkt)) + { + mLowPriorityInbound.popPacket(pkt); + } + + S32 packet_size = pkt.getSize(); + mLastSender = pkt.getHost(); + mLastReceivingIF = pkt.getReceivingInterface(); + + if (packet_size > 0) + { + memcpy(datap, pkt.getData(), packet_size); + } + return packet_size; + } + + // Read directly from the socket. + bool drop = computeDrop(); + S32 packet_size = 0; + if (LLProxy::isSOCKSProxyEnabled()) + { + char buffer[NET_BUFFER_SIZE + SOCKS_HEADER_SIZE]; /* Flawfinder ignore */ + packet_size = receive_packet(mSocket, buffer); + if (packet_size > 0) + { + mActualBytesIn += packet_size; + } + if (packet_size > SOCKS_HEADER_SIZE) + { + if (drop) + { + packet_size = 0; + } + else + { + // *FIX We are assuming ATYP is 0x01 (IPv4), not 0x03 (hostname) or 0x04 (IPv6) + packet_size -= SOCKS_HEADER_SIZE; + memcpy(datap, buffer + SOCKS_HEADER_SIZE, packet_size); + proxywrap_t* header = static_cast(static_cast(buffer)); + mLastSender.setAddress(header->addr); + mLastSender.setPort(ntohs(header->port)); + mLastReceivingIF = ::get_receiving_interface(); + } + } + else + { + packet_size = 0; + } + } + else + { + packet_size = receive_packet(mSocket, datap); + if (packet_size > 0) + { + mActualBytesIn += packet_size; + if (drop) + { + packet_size = 0; + } + else + { + mLastSender = ::get_sender(); + mLastReceivingIF = ::get_receiving_interface(); + } + } + } + return packet_size; +} + +S32 LLMessageSystem::bufferInboundPacket() +{ + LLHost invalid_host; + LLPacketBuffer pkt(invalid_host, nullptr, 0); + S32 packet_size = 0; + + if (LLProxy::isSOCKSProxyEnabled()) + { + char buffer[NET_BUFFER_SIZE + SOCKS_HEADER_SIZE]; /* Flawfinder ignore */ + packet_size = receive_packet(mSocket, buffer); + if (packet_size > 0) + { + mActualBytesIn += packet_size; + if (packet_size > SOCKS_HEADER_SIZE) + { + // *FIX We are assuming ATYP is 0x01 (IPv4), not 0x03 (hostname) or 0x04 (IPv6) + proxywrap_t* header = static_cast(static_cast(buffer)); + LLHost sender; + sender.setAddress(header->addr); + sender.setPort(ntohs(header->port)); + packet_size -= SOCKS_HEADER_SIZE; + pkt.init(buffer + SOCKS_HEADER_SIZE, packet_size, sender); + } + else + { + packet_size = 0; + } + } + } + else + { + pkt.init(mSocket); + packet_size = pkt.getSize(); + if (packet_size > 0) + { + mActualBytesIn += packet_size; + } + } + + if (packet_size >= (S32)LL_MINIMUM_VALID_PACKET_SIZE && !computeDrop()) + { + const char* data = pkt.getData(); + LLCircuitData* cdp = mCircuitInfo.findCircuit(pkt.getHost()); + TPACKETID recv_packet_id = ntohl(*((U32*)(&data[1]))); + + // Harvest piggybacked ACKs for outbound messages from the packet tail of this inbound message + if (cdp && (data[0] & LL_ACK_FLAG)) + { + U8 num_acks = (U8)data[packet_size - 1]; + S32 true_rcv_size = packet_size - 1; + if (true_rcv_size >= (S32)(num_acks * sizeof(TPACKETID) + LL_MINIMUM_VALID_PACKET_SIZE)) + { + TPACKETID ack_id; + U32 mem_id = 0; + for (S32 i = 0; i < num_acks; ++i) + { + true_rcv_size -= sizeof(TPACKETID); + memcpy(&mem_id, &data[true_rcv_size], sizeof(TPACKETID)); /* Flawfinder: ignore */ + ack_id = ntohl(mem_id); + cdp->ackReliablePacket(ack_id); + } + if (!cdp->getUnackedPacketCount()) + { + mCircuitInfo.mUnackedCircuitMap.erase(cdp->mHost); + } + } + } + + // ACK inbound reliable packet ASAP + if (cdp && (data[0] & LL_RELIABLE_FLAG)) + { + cdp->collectRAck(recv_packet_id); + } + + if (isHighPriorityMessage(pkt)) + { + mHighPriorityInbound.pushPacket(pkt); + } + else + { + mLowPriorityInbound.pushPacket(pkt); + } + } + + return packet_size; +} + +bool LLMessageSystem::sendPacketToSocket(const char* datap, S32 data_size, LLHost host) +{ + mActualBytesOut += data_size; + if (!LLProxy::isSOCKSProxyEnabled()) + { + return send_packet(mSocket, datap, data_size, host.getAddress(), host.getPort()); + } + + char headered_send_buffer[NET_BUFFER_SIZE + SOCKS_HEADER_SIZE]; + + proxywrap_t* socks_header = static_cast(static_cast(&headered_send_buffer)); + socks_header->rsv = 0; + socks_header->addr = host.getAddress(); + socks_header->port = htons(host.getPort()); + socks_header->atype = ADDRESS_IPV4; + socks_header->frag = 0; + + memcpy(headered_send_buffer + SOCKS_HEADER_SIZE, datap, data_size); + + return send_packet(mSocket, + headered_send_buffer, + data_size + SOCKS_HEADER_SIZE, + LLProxy::getInstance()->getUDPProxy().getAddress(), + LLProxy::getInstance()->getUDPProxy().getPort()); +} + +void LLMessageSystem::dumpPacketRingStats() +{ + mNumDroppedPacketsTotal += mNumDroppedPackets; + LL_INFOS("Messaging") << "buffered_packets=" << getNumBufferedPackets() + << "buffered_bytes=" << (mHighPriorityInbound.getNumBufferedBytes() + mLowPriorityInbound.getNumBufferedBytes()) + << "recently_dropped=" << mNumDroppedPackets + << "total_dropped=" << mNumDroppedPacketsTotal + << "dropped_percentage=" << mDropPercentage << "%" + << "bytes_IN=" << mActualBytesIn + << "bytes_OUT=" << mActualBytesOut << LL_ENDL; + mNumDroppedPackets = 0; } void LLMessageSystem::copyMessageReceivedToSend() @@ -1277,7 +1544,7 @@ S32 LLMessageSystem::sendMessage(const LLHost &host) } bool success; - success = mPacketRing.sendPacket(mSocket, (char *)buf_ptr, buffer_length, host); + success = sendPacketToSocket((char *)buf_ptr, buffer_length, host); if (!success) { @@ -2607,7 +2874,7 @@ void LLMessageSystem::summarizeLogs(std::ostream& str) str << buffer << std::endl << std::endl; buffer = llformat( "SendPacket failures: %20d", mSendPacketFailureCount); str << buffer << std::endl; - buffer = llformat( "Dropped packets: %20d", mDroppedPackets); + buffer = llformat( "Dropped packets: %20d", getTotalNumDroppedPackets()); str << buffer << std::endl; buffer = llformat( "Resent packets: %20d", mResentPackets); str << buffer << std::endl; @@ -3333,7 +3600,7 @@ void LLMessageSystem::establishBidirectionalTrust(const LLHost &host, S64 frame_ void LLMessageSystem::dumpPacketToLog() { - LL_WARNS("Messaging") << "Packet Dump from:" << mPacketRing.getLastSender() << LL_ENDL; + LL_WARNS("Messaging") << "Packet Dump from:" << mLastSender << LL_ENDL; LL_WARNS("Messaging") << "Packet Size:" << mTrueReceiveSize << LL_ENDL; char line_buffer[256]; /* Flawfinder: ignore */ S32 i; -- cgit v1.3