Method ProcessInConnectionPacket

library/cpp/netliba/v12/udp_host.cpp:1061–1108

    }

    bool TUdpHost::ProcessInConnectionPacket(const EUdpCmd cmd, const char* pktData, const char* pktEnd, const ui8 originalCmd,
                                             const sockaddr_in6& fromAddress, const sockaddr_in6& dstAddress, TAutoPtr<TUdpRecvPacket> recvBuf) {
        Y_ASSERT(IsInConnectionCmd(cmd));
        Y_ASSERT(pktData <= pktEnd);

        TGUID connectionGuid;
        TConnectionSettings settings;
        TOptionsVector opt;

        TGUID thatSideGuid;
        if (!ReadInConnectionPacketHeaderTail(&pktData, pktEnd, originalCmd, &connectionGuid, &thatSideGuid, &settings, &opt) ||
            connectionGuid.IsEmpty() || thatSideGuid.IsEmpty()) // validation
        {
            Y_ASSERT(false);
            return false;
        }

        TConnection* connection = nullptr;
        if (const TIntrusivePtr<IConnection>* c = Connections.FindPtr(connectionGuid)) {
            connection = CheckedCast<TConnection*>(c->Get());
            //Y_ASSERT(memcmp(&connection->GetWinsockAddress(), &fromAddress, sizeof(fromAddress)) == 0);

            // ignore imitator
            if (GetUdpAddress(fromAddress) != connection->GetAddress()) {
                Y_ASSERT(false);
                return true;
            }

        } else if (IsAckCmd(cmd)) {
            // OK, it seems we already deleted connection and got late duplicate ACK
            return true;

        } else {
            const TUdpAddress udpFromAddress = GetUdpAddress(fromAddress);
            const TUdpAddress toAddress = GetUdpAddress(dstAddress);

            connection = new TConnection(udpFromAddress, toAddress, settings, connectionGuid, UdpTransferTimeout);
            Connections[connectionGuid] = connection;
        }

        const bool thatSideHasChanged = !connection->CheckThatSideGuid(thatSideGuid);

        // actually GetAlivePeerLink would be enough
        connection->GetAlivePeerLink().GetUdpCongestion()->MarkAlive();

        Y_ASSERT(IsTransferCmd(cmd) || IsPingCmd(cmd));
        return IsTransferCmd(cmd) ? ProcessTransferPacket(cmd, pktData, pktEnd, recvBuf, connection, thatSideHasChanged, opt) : ProcessPingPacket(cmd, pktData, pktEnd, fromAddress, connection);
    }

    bool TUdpHost::ProcessTransferPacket(const EUdpCmd cmd, const char* pktData, const char* pktEnd,
                                         TAutoPtr<TUdpRecvPacket> recvBuf, TConnection* connection, const bool thatSideHasChanged, const TOptionsVector& opt) {