RCONServer.cpp

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// RCONServer.cpp

// Implements the cRCONServer class representing the RCON server

#include "Globals.h"
#include "IniFile.h"
#include "RCONServer.h"
#include "Server.h"
#include "Root.h"
#include "CommandOutput.h"





// Disable MSVC warnings:
#if defined(_MSC_VER)
    #pragma warning(push)
    #pragma warning(disable:4355)  // 'this' : used in base member initializer list
#endif





enum
{
    // Client -> Server:
    RCON_PACKET_COMMAND = 2,
    RCON_PACKET_LOGIN   = 3,

    // Server -> Client:
    RCON_PACKET_RESPONSE = 2,
} ;





// cRCONListenCallbacks:

class cRCONListenCallbacks:
    public cNetwork::cListenCallbacks
{
public:
    cRCONListenCallbacks(cRCONServer & a_RCONServer, UInt16 a_Port):
        m_RCONServer(a_RCONServer),
        m_Port(a_Port)
    {
    }

protected:
    cRCONServer & m_RCONServer;

    UInt16 m_Port;

    // cNetwork::cListenCallbacks overrides:
    virtual cTCPLink::cCallbacksPtr OnIncomingConnection(const AString & a_RemoteIPAddress, UInt16 a_RemotePort) override
    {
        LOG("RCON Client \"%s\" connected!", a_RemoteIPAddress.c_str());
        return std::make_shared<cRCONServer::cConnection>(m_RCONServer, a_RemoteIPAddress);
    }
    virtual void OnAccepted(cTCPLink & a_Link) override {}
    virtual void OnError(int a_ErrorCode, const AString & a_ErrorMsg) override
    {
        LOGWARNING("RCON server error on port %d: %d (%s)", m_Port, a_ErrorCode, a_ErrorMsg.c_str());
    }
};





// cRCONCommandOutput:

class cRCONCommandOutput :
    public cCommandOutputCallback
{
public:
    cRCONCommandOutput(cRCONServer::cConnection & a_Connection, UInt32 a_RequestID) :
        m_Connection(a_Connection),
        m_RequestID(a_RequestID)
    {
    }

    // cCommandOutputCallback overrides:
    virtual void Out(const AString & a_Text) override
    {
        m_Buffer.append(a_Text);
    }

    virtual void Finished(void) override
    {
        m_Connection.SendResponse(m_RequestID, RCON_PACKET_RESPONSE, static_cast<UInt32>(m_Buffer.size()), m_Buffer.c_str());
        delete this;
    }

protected:
    cRCONServer::cConnection & m_Connection;
    UInt32 m_RequestID;
    AString m_Buffer;
} ;





// cRCONServer:

cRCONServer::cRCONServer(cServer & a_Server) :
    m_Server(a_Server)
{
}





cRCONServer::~cRCONServer()
{
    for (auto srv: m_ListenServers)
    {
        srv->Close();
    }
}





void cRCONServer::Initialize(cSettingsRepositoryInterface & a_Settings)
{
    if (!a_Settings.GetValueSetB("RCON", "Enabled", false))
    {
        return;
    }

    // Read the password, don't allow an empty one:
    m_Password = a_Settings.GetValueSet("RCON", "Password", "");
    if (m_Password.empty())
    {
        LOGWARNING("RCON is requested, but the password is not set. RCON is now disabled.");
        return;
    }

    // Read the listening ports for RCON from config:
    AStringVector Ports = ReadUpgradeIniPorts(a_Settings, "RCON", "Ports", "PortsIPv4", "PortsIPv6", "25575");

    // Start listening on each specified port:
    for (auto port: Ports)
    {
        UInt16 PortNum;
        if (!StringToInteger(port, PortNum))
        {
            LOGINFO("Invalid RCON port value: \"%s\". Ignoring.", port.c_str());
            continue;
        }
        auto Handle = cNetwork::Listen(PortNum, std::make_shared<cRCONListenCallbacks>(*this, PortNum));
        if (Handle->IsListening())
        {
            m_ListenServers.push_back(Handle);
        }
    }

    if (m_ListenServers.empty())
    {
        LOGWARNING("RCON is enabled but no valid ports were found. RCON is not accessible.");
    }
}





// cRCONServer::cConnection:

cRCONServer::cConnection::cConnection(cRCONServer & a_RCONServer, const AString & a_IPAddress) :
    m_IsAuthenticated(false),
    m_RCONServer(a_RCONServer),
    m_IPAddress(a_IPAddress)
{
}





void cRCONServer::cConnection::OnLinkCreated(cTCPLinkPtr a_Link)
{
    m_Link = a_Link;
}





void cRCONServer::cConnection::OnReceivedData(const char * a_Data, size_t a_Size)
{
    ASSERT(m_Link != nullptr);

    // Append data to the buffer:
    m_Buffer.append(a_Data, a_Size);

    // Process the packets in the buffer:
    while (m_Buffer.size() >= 14)
    {
        UInt32 Length = UIntFromBuffer(m_Buffer.data());
        if (Length > 1500)
        {
            // Too long, drop the connection
            LOGWARNING("Received an invalid RCON packet length (%d), dropping RCON connection to %s.",
                Length, m_IPAddress.c_str()
            );
            m_Link->Close();
            m_Link.reset();
            return;
        }
        if (Length > static_cast<UInt32>(m_Buffer.size() + 4))
        {
            // Incomplete packet yet, wait for more data to come
            return;
        }

        UInt32 RequestID  = UIntFromBuffer(m_Buffer.data() + 4);
        UInt32 PacketType = UIntFromBuffer(m_Buffer.data() + 8);
        if (!ProcessPacket(RequestID, PacketType, Length - 10, m_Buffer.data() + 12))
        {
            m_Link->Close();
            m_Link.reset();
            return;
        }
        m_Buffer.erase(0, Length + 4);
    }  // while (m_Buffer.size() >= 14)
}





void cRCONServer::cConnection::OnRemoteClosed(void)
{
    m_Link.reset();
}





void cRCONServer::cConnection::OnError(int a_ErrorCode, const AString & a_ErrorMsg)
{
    LOGD("Error in RCON connection %s: %d (%s)", m_IPAddress.c_str(), a_ErrorCode, a_ErrorMsg.c_str());
    m_Link.reset();
}





bool cRCONServer::cConnection::ProcessPacket(UInt32 a_RequestID, UInt32 a_PacketType, UInt32 a_PayloadLength, const char * a_Payload)
{
    switch (a_PacketType)
    {
        case RCON_PACKET_LOGIN:
        {
            if (strncmp(a_Payload, m_RCONServer.m_Password.c_str(), a_PayloadLength) != 0)
            {
                LOGINFO("RCON: Invalid password from client %s, dropping connection.", m_IPAddress.c_str());
                SendResponse(0xffffffffU, RCON_PACKET_RESPONSE, 0, nullptr);
                return false;
            }
            m_IsAuthenticated = true;

            LOGD("RCON: Client at %s has successfully authenticated", m_IPAddress.c_str());

            // Send OK response:
            SendResponse(a_RequestID, RCON_PACKET_RESPONSE, 0, nullptr);
            return true;
        }

        case RCON_PACKET_COMMAND:
        {
            if (!m_IsAuthenticated)
            {
                char AuthNeeded[] = "You need to authenticate first!";
                SendResponse(a_RequestID, RCON_PACKET_RESPONSE, sizeof(AuthNeeded), AuthNeeded);
                return false;
            }

            AString cmd(a_Payload, a_PayloadLength);
            LOGD("RCON command from %s: \"%s\"", m_IPAddress.c_str(), cmd.c_str());
            cRoot::Get()->ExecuteConsoleCommand(cmd, *(new cRCONCommandOutput(*this, a_RequestID)));

            // Send an empty response:
            SendResponse(a_RequestID, RCON_PACKET_RESPONSE, 0, nullptr);
            return true;
        }
    }

    // Unknown packet type, drop the connection:
    LOGWARNING("RCON: Client at %s has sent an unknown packet type %d, dropping connection.",
        m_IPAddress.c_str(), a_PacketType
    );
    return false;
}





UInt32 cRCONServer::cConnection::UIntFromBuffer(const char * a_Buffer)
{
    const Byte * Buffer = reinterpret_cast<const Byte *>(a_Buffer);
    return static_cast<UInt32>((Buffer[3] << 24) | (Buffer[2] << 16) | (Buffer[1] << 8) | Buffer[0]);
}





void cRCONServer::cConnection::UIntToBuffer(UInt32 a_Value, char * a_Buffer)
{
    a_Buffer[0] = static_cast<char>(a_Value & 0xff);
    a_Buffer[1] = static_cast<char>((a_Value >> 8)  & 0xff);
    a_Buffer[2] = static_cast<char>((a_Value >> 16) & 0xff);
    a_Buffer[3] = static_cast<char>((a_Value >> 24) & 0xff);
}





void cRCONServer::cConnection::SendResponse(UInt32 a_RequestID, UInt32 a_PacketType, UInt32 a_PayloadLength, const char * a_Payload)
{
    ASSERT((a_PayloadLength == 0) || (a_Payload != nullptr));  // Either zero data to send, or a valid payload ptr
    ASSERT(m_Link != nullptr);

    char Buffer[12];
    UInt32 Length = a_PayloadLength + 10;
    UIntToBuffer(Length, Buffer);
    UIntToBuffer(a_RequestID, Buffer + 4);
    UIntToBuffer(a_PacketType, Buffer + 8);
    m_Link->Send(Buffer, 12);
    if (a_PayloadLength > 0)
    {
        m_Link->Send(a_Payload, a_PayloadLength);
    }
    m_Link->Send("\0", 2);  // Send two zero chars as the padding
}