Added CRC to packets
Verify that data is correctly ordered and reject packets that aren't. Also generates a random game id to ensure packets are coming from legitimate clients.
This commit is contained in:
Boondorl
Ricardo Luís Vaz Silva
parent
9e2b1f9c4c
commit
7877018471
3 changed files with 67 additions and 32 deletions
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@ -78,6 +78,7 @@
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#include "c_cvars.h"
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#include "version.h"
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#include "i_net.h"
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#include "m_random.h"
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/* [Petteri] Get more portable: */
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#ifndef __WIN32__
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@ -162,13 +163,14 @@ int consoleplayer = 0;
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int Net_Arbitrator = 0;
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FClientStack NetworkClients = {};
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uint32_t GameID = DEFAULT_GAME_ID;
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uint64_t GameID = 0u;
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uint8_t TicDup = 1u;
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int MaxClients = 1;
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int RemoteClient = -1;
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size_t NetBufferLength = 0u;
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uint8_t NetBuffer[MAX_MSGLEN] = {};
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static FRandom GameIDGen = {};
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static u_short GamePort = (IPPORT_USERRESERVED + 29);
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static SOCKET MySocket = INVALID_SOCKET;
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static FConnection Connected[MAXPLAYERS] = {};
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@ -483,22 +485,34 @@ static void SendPacket(const sockaddr_in& to)
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assert(!(NetBuffer[0] & NCMD_COMPRESSED));
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uLong size = MaxTransmitSize - 1u;
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int res = -1;
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uint8_t* dataStart = &TransmitBuffer[4];
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uLong size = MaxTransmitSize - 5u;
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if (NetBufferLength >= MinCompressionSize)
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{
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TransmitBuffer[0] = NetBuffer[0] | NCMD_COMPRESSED;
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*dataStart = NetBuffer[0] | NCMD_COMPRESSED;
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const int res = compress2(dataStart + 1, &size, NetBuffer + 1, NetBufferLength - 1u, 9);
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if (res != Z_OK)
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I_Error("Net compression failed (zlib error %d)", res);
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res = compress2(TransmitBuffer + 1, &size, NetBuffer + 1, uint32_t(NetBufferLength - 1u), 9);
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++size;
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}
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if (res == Z_OK && size < static_cast<uLong>(NetBufferLength))
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res = sendto(MySocket, (const char*)TransmitBuffer, (int)size, 0, (const sockaddr*)&to, sizeof(to));
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else if (NetBufferLength > MaxTransmitSize)
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I_Error("Net compression failed (zlib error %d)", res);
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else
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res = sendto(MySocket, (const char*)NetBuffer, (int)NetBufferLength, 0, (const sockaddr*)&to, sizeof(to));
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{
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memcpy(dataStart, NetBuffer, NetBufferLength);
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size = NetBufferLength;
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}
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if (size + 4 > MaxTransmitSize)
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I_Error("Failed to compress data down to acceptable transmission size");
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// If a connection packet, don't check the game id since they might not have it yet.
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const uint32_t crc = (NetBuffer[0] & NCMD_SETUP) ? CalcCRC32(dataStart, size) : AddCRC32(CalcCRC32(dataStart, size), (uint8_t*)&GameID, sizeof(GameID));
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TransmitBuffer[0] = crc >> 24;
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TransmitBuffer[1] = crc >> 16;
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TransmitBuffer[2] = crc >> 8;
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TransmitBuffer[3] = crc;
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sendto(MySocket, (const char*)TransmitBuffer, size + 4, 0, (const sockaddr*)&to, sizeof(to));
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}
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static void GetPacket(sockaddr_in* const from = nullptr)
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@ -544,7 +558,8 @@ static void GetPacket(sockaddr_in* const from = nullptr)
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}
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else if (msgSize > 0)
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{
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if (client == -1 && !(TransmitBuffer[0] & NCMD_SETUP))
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const uint8_t* dataStart = &TransmitBuffer[4];
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if (client == -1 && !(*dataStart & NCMD_SETUP))
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{
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msgSize = 0;
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}
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@ -558,25 +573,37 @@ static void GetPacket(sockaddr_in* const from = nullptr)
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}
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else
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{
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NetBuffer[0] = (TransmitBuffer[0] & ~NCMD_COMPRESSED);
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if (TransmitBuffer[0] & NCMD_COMPRESSED)
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const uint32_t check = (*dataStart & NCMD_SETUP) ? CalcCRC32(dataStart, msgSize - 4) : AddCRC32(CalcCRC32(dataStart, msgSize - 4), (uint8_t*)GameID, sizeof(GameID));
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const uint32_t crc = (TransmitBuffer[0] << 24) | (TransmitBuffer[1] << 16) | (TransmitBuffer[2] << 8) | TransmitBuffer[3];
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if (check != crc)
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{
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uLongf size = MAX_MSGLEN - 1;
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int err = uncompress(NetBuffer + 1, &size, TransmitBuffer + 1, msgSize - 1);
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if (err != Z_OK)
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{
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Printf("Net decompression failed (zlib error %s)\n", M_ZLibError(err).GetChars());
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client = -1;
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msgSize = 0;
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}
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else
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{
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msgSize = size + 1;
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}
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DPrintf(DMSG_NOTIFY, "Checksum on packet failed: expected %u, got %u", check, crc);
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client = -1;
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msgSize = 0;
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}
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else
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{
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memcpy(NetBuffer + 1, TransmitBuffer + 1, msgSize - 1);
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NetBuffer[0] = (*dataStart & ~NCMD_COMPRESSED);
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if (*dataStart & NCMD_COMPRESSED)
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{
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uLongf size = MAX_MSGLEN - 1;
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int err = uncompress(NetBuffer + 1, &size, dataStart + 1, msgSize - 5);
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if (err != Z_OK)
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{
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Printf("Net decompression failed (zlib error %s)\n", M_ZLibError(err).GetChars());
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client = -1;
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msgSize = 0;
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}
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else
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{
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msgSize = size + 1;
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}
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}
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else
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{
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msgSize -= 4;
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memcpy(NetBuffer + 1, dataStart + 1, msgSize - 1);
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}
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}
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}
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}
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@ -847,7 +874,15 @@ static bool Host_CheckForConnections(void* connected)
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{
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NetBuffer[1] = PRE_GAME_INFO;
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NetBuffer[2] = TicDup;
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NetBufferLength = 3u;
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NetBuffer[3] = GameID >> 56;
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NetBuffer[4] = GameID >> 48;
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NetBuffer[5] = GameID >> 40;
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NetBuffer[6] = GameID >> 32;
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NetBuffer[7] = GameID >> 24;
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NetBuffer[8] = GameID >> 16;
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NetBuffer[9] = GameID >> 8;
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NetBuffer[10] = GameID;
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NetBufferLength = 11u;
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uint8_t* stream = &NetBuffer[NetBufferLength];
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NetBufferLength += Net_SetGameInfo(stream);
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@ -931,6 +966,7 @@ static bool HostGame(int arg, bool forcedNetMode)
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if (MaxClients > MAXPLAYERS)
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I_FatalError("Cannot host a game with %u players. The limit is currently %u", MaxClients, MAXPLAYERS);
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GameID = GameIDGen.GenRand64();
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NetworkClients += 0;
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Connected[consoleplayer].Status = CSTAT_READY;
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Net_SetupUserInfo();
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@ -1092,7 +1128,9 @@ static bool Guest_ContactHost(void* unused)
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if (!Connected[consoleplayer].bHasGameInfo)
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{
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TicDup = clamp<int>(NetBuffer[2], 1, MAXTICDUP);
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uint8_t* stream = &NetBuffer[3];
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GameID = ((uint64_t)NetBuffer[3] << 56) | ((uint64_t)NetBuffer[4] << 48) | ((uint64_t)NetBuffer[5] << 40) | ((uint64_t)NetBuffer[6] << 32)
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| ((uint64_t)NetBuffer[7] << 24) | ((uint64_t)NetBuffer[8] << 16) | ((uint64_t)NetBuffer[9] << 8) | (uint64_t)NetBuffer[10];
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uint8_t* stream = &NetBuffer[11];
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Net_ReadGameInfo(stream);
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Connected[consoleplayer].bHasGameInfo = true;
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}
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@ -1255,6 +1293,7 @@ bool I_InitNetwork()
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else
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{
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// single player game
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GameID = GameIDGen.GenRand64();
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TicDup = 1;
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NetworkClients += 0;
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Connected[0].Status = CSTAT_READY;
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@ -8,7 +8,6 @@ inline constexpr size_t MAXPLAYERS = 64u;
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enum ENetConstants
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{
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DEFAULT_GAME_ID = 0x12345678,
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BACKUPTICS = 35 * 5, // Remember up to 5 seconds of data.
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MAXTICDUP = 3,
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MAXSENDTICS = 35 * 1, // Only send up to 1 second of data at a time.
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@ -67,7 +66,7 @@ extern size_t NetBufferLength;
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extern uint8_t TicDup;
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extern int RemoteClient;
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extern int MaxClients;
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extern uint32_t GameID;
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extern uint64_t GameID;
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bool I_InitNetwork();
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void I_ClearClient(size_t client);
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@ -1695,9 +1695,6 @@ bool D_CheckNetGame()
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if (!I_InitNetwork())
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return false;
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if (GameID != DEFAULT_GAME_ID)
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I_FatalError("Invalid id set for network buffer");
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if (Args->CheckParm("-extratic"))
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net_extratic = true;
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