diff options
Diffstat (limited to 'src/communication.cc')
| -rw-r--r-- | src/communication.cc | 125 |
1 files changed, 59 insertions, 66 deletions
diff --git a/src/communication.cc b/src/communication.cc index cdfb6c7..b981d1e 100644 --- a/src/communication.cc +++ b/src/communication.cc @@ -241,26 +241,53 @@ void ExitLoadHistory(void){ // Connection Output // ============================================================================= -bool WriteToSocket(TConnection *Connection, uint8 *Buffer, int Size){ - // IMPORTANT(fusion): The caller must ensure `Buffer` have two extra bytes - // at the beginning and enough room at the end to properly add padding for - // XTEA encryption when needed. `Size` refers to the payload size which - // starts after the first two extra bytes. See note in `SendData`. - - while((Size % 8) != 0){ - Buffer[Size + 2] = rand_r(&Connection->RandomSeed); +static constexpr int GetPacketSize(int DataSize){ + // NOTE(fusion): This can be annoying but we're compiling with C++11 which + // means constexpr functions can only have a single return statement. +#if __cplusplus > 201103L + int EncryptedSize = ((DataSize + 2) + 7) & ~7; + int PacketSize = EncryptedSize + 2; + return PacketSize; +#else + return (((DataSize + 2) + 7) & ~7) + 2; +#endif +} + +bool WriteToSocket(TConnection *Connection, uint8 *Buffer, int Size, int MaxSize){ + // IMPORTANT(fusion): The final packet will have the following layout: + // PLAIN: + // 0 .. 2 => Encrypted Size + // ENCRYPTED: + // 2 .. 4 => Data Size + // 4 .. => Data + Padding + // + // The caller must ensure `Buffer` has four extra bytes at the beginning so + // the packet and payload sizes can be written. It should also ensure that + // `(MaxSize % 8) == 2` so we can always add the necessary amount of padding + // for encryption. + ASSERT(Size >= 4 && Size <= MaxSize && MaxSize <= UINT16_MAX); + + int DataSize = Size - 4; + while((Size % 8) != 2 && Size < MaxSize){ + Buffer[Size] = rand_r(&Connection->RandomSeed); Size += 1; } - for(int i = 0; i < Size; i += 8){ - Connection->SymmetricKey.encrypt(&Buffer[i + 2]); + if((Size % 8) != 2){ + error("WriteToSocket: Failed to add padding (Size: %d, MaxSize: %d)\n", + Size, MaxSize); + return false; } - TWriteBuffer WriteBuffer(Buffer, 2); - WriteBuffer.writeWord((uint16)Size); + TWriteBuffer WriteBuffer(Buffer, 4); + WriteBuffer.writeWord((uint16)(Size - 2)); + WriteBuffer.writeWord((uint16)(DataSize)); + for(int i = 2; i < Size; i += 8){ + Connection->SymmetricKey.encrypt(&Buffer[i]); + } int Attempts = 50; - int BytesToWrite = Size + 2; + int BytesToWrite = Size; uint8 *WritePtr = Buffer; while(BytesToWrite > 0){ int BytesWritten = (int)write(Connection->GetSocket(), WritePtr, BytesToWrite); @@ -324,19 +351,22 @@ bool SendLoginMessage(TConnection *Connection, int Type, const char *Message, in // IMPORTANT(fusion): This is doing the same thing as `SendData` but in a // smaller scale and building the packet directly instead of using the // connection's write buffer. - uint8 Data[302]; // 2 + 300 - TWriteBuffer WriteBuffer(Data + 2, sizeof(Data) - 2); - WriteBuffer.writeWord(0); - WriteBuffer.writeByte((uint8)Type); - WriteBuffer.writeString(Message); - if(Type == 22){ - WriteBuffer.writeByte(WaitingTime); - } + try{ + uint8 Data[GetPacketSize(300)]; + TWriteBuffer WriteBuffer(Data, sizeof(Data)); + WriteBuffer.writeWord(0); // EncryptedSize + WriteBuffer.writeWord(0); // DataSize + WriteBuffer.writeByte((uint8)Type); + WriteBuffer.writeString(Message); + if(Type == 22){ + WriteBuffer.writeByte(WaitingTime); + } - int Size = WriteBuffer.Position; - WriteBuffer.Position = 0; - WriteBuffer.writeWord((uint16)(Size - 2)); - return WriteToSocket(Connection, Data, Size); + return WriteToSocket(Connection, Data, WriteBuffer.Position, WriteBuffer.Size); + }catch(const char *str){ + error("SendLoginMessage: Fehler beim Füllen des Puffers (%s)\n", str); + return true; + } } bool SendData(TConnection *Connection){ @@ -345,24 +375,8 @@ bool SendData(TConnection *Connection){ return false; } - // - // IMPORTANT(fusion): The final packet will have this layout: - // PLAIN: - // 0 .. 2 => Encrypted Size - // ENCRYPTED: - // 2 .. 4 => Data Size - // 4 .. => Data + Padding - // - // The ENCRYPTED size needs to be a multiple of 8 for XTEA encryption and - // `WriteToSocket` will add padding to ensure it is. This also requires us - // to ensure the passed buffer has enough room for it, so we don't write out - // of bounds. - // - int DataSize = Connection->NextToCommit - Connection->NextToSend; - int EncryptedSize = (DataSize + 2); - int EncryptedSizeAligned = (EncryptedSize + 7) & ~7; - int PacketSize = EncryptedSizeAligned + 2; + int PacketSize = GetPacketSize(DataSize); // TODO(fusion): The maximum size of a packet depends on the size of // `Connection->OutData` and I don't think we'd have a problem with @@ -371,8 +385,8 @@ bool SendData(TConnection *Connection){ // problem. uint8 *Buffer = (uint8*)alloca(PacketSize); TWriteBuffer WriteBuffer(Buffer, PacketSize); - WriteBuffer.writeWord(0); - WriteBuffer.writeWord((uint16)DataSize); + WriteBuffer.writeWord(0); // EncryptedSize + WriteBuffer.writeWord(0); // DataSize // NOTE(fusion): `Connection->OutData` is a ring buffer so we need to check // if the data we're currently sending is wrapping around, in which case we'd @@ -387,34 +401,13 @@ bool SendData(TConnection *Connection){ WriteBuffer.writeBytes(&Connection->OutData[0], DataEnd - OutDataSize); } - bool Result = WriteToSocket(Connection, Buffer, DataSize); + bool Result = WriteToSocket(Connection, Buffer, WriteBuffer.Position, WriteBuffer.Size); if(Result){ Connection->NextToSend += DataSize; } return Result; } -bool SendData(TConnection *Connection, const uint8 *Data, int Size){ - if(Connection == NULL){ - error("SendData: Connection ist NULL.\n"); - return false; - } - - // TODO(fusion): Why are we returning true for invalid parameters? - if(Data == NULL){ - error("SendData: Data ist NULL.\n"); - return true; - } - - // TODO(fusion): Why do we leave extra two bytes unassigned at the beginning? - // `SendData` should already take care of building the packet properly so this - // is something else or a bug, if this function is even used. - memcpy(&Connection->OutData[2], Data, Size); - Connection->NextToSend = 0; - Connection->NextToCommit = Size + 2; - return SendData(Connection); -} - // Waiting List // ============================================================================= bool GetWaitinglistEntry(const char *Name, uint32 *NextTry, bool *FreeAccount, bool *Newbie){ |