Processing Incoming Packets

CrimsonGT · **Author**

Im working on processing incoming packets in an effort to cache the information sent for A2S_INFO queries, and to block A2C_PRINT packets completely. I havent gotten to the A2C_PRINT packets yet, but im assuming I can just check for packets starting with "\xFF\xFF\xFF\xFF\x6C" according to devicenull's page and block them using a recv() or recvfrom() hook.

Im stuck on the A2S_INFO spam though. I was going to try using ProcessConnectionlessPacket(netpacket_t *packet) but the netpacket_s struct isnt available to look at so I decided to detour ReplyInfo() instead. I have been working on it for 2 days trying to recreate the information and cache it for X seconds, and return it instead of letting CMaster::ReplyInfo() run everytime one comes in. (This function attempts to rebuild the information everytime its called, so getting flooded by A2S_INFO requests lags out the server) My code is crashing out when I issue the Net_SendPacket() and I can only assume I have pieced together the packet incorrectly. Anyways, heres my code in hopes someone spots something.

*Edit*

I have hardcoded some of the information as I have not found a way of getting the game version, type, or protocol via code. I used the information from http://developer.valvesoftware.com/wiki/Server_Queries to build it.

Code:

unsigned char pData[6144];
bf_write buffer("SVC_ReplyInfo", &pData, 6144, -1);

void BuildReplyInfo()
{
    buffer.Reset();

    int passByte = 00;
    const char *pGamePass = iserver->GetPassword();
    if(pGamePass)
        passByte = 01;

    //http://www.ascii.cl/
    //http://developer.valvesoftware.com/wiki/Server_Queries
    buffer.WriteLong(-1);
    buffer.WriteByte(73);                                //Type
    buffer.WriteByte(14);                                //Protocol Version (0x07 is Steam Version, 0x30 is Goldsource)
    buffer.WriteString(iserver->GetName());                //Hostname
    buffer.WriteString(iserver->GetMapName());            //MapName
    buffer.WriteString("tf");//pGameDir);                //Game Directory
    buffer.WriteString(server->GetGameDescription());    //Game Description
    buffer.WriteShort(engine->GetAppID());                //AppID
    buffer.WriteByte(iserver->GetClientCount());        //Number of Players
    buffer.WriteByte(iserver->GetMaxClients());            //Max Players
    buffer.WriteByte(iserver->GetNumFakeClients());        //Number of Bots
    buffer.WriteByte(100);                                //"d" (100) for Dedicated
    buffer.WriteByte(119);                                //Operating System "w" (119) for Windows "l" (108) for Linux
    buffer.WriteByte(passByte);                            //Passworded or Not
    buffer.WriteByte(01);                                //VAC Secured
    buffer.WriteString("1.0.7.8");                        //Game Version
}

DETOUR_DECL_MEMBER2(ReplyInfo, void *, void *, netaddr, void *, gameserver)
{
    BuildReplyInfo();

    int *x = (int *)(((unsigned char *)gameserver) + 8);
    Net_SendPacket(NULL, *x, netaddr, buffer.m_pData, buffer.GetNumBytesWritten());

    return NULL;
}