How to send properly files in a client-server application? - c

Question

I want to make a client-server application when a client can register, login, broadcast a message to another clients, send files and so on. Everything, except sending files works pretty well.
In the client application I made a separate thread for every file that I want to send. Reading the file is successful, but sending is not that good. I should make a thread in server project for receiving the bytes sent by the client?
I want sending files to be asynchronous, so that another clients can communicate with server when server is receiving a file.
The thread for reading file and sending data to server:
DWORD WINAPI SendFile(LPVOID param)
{
FileStruct* fileStruct = (FileStruct*)param;
CM_DATA_BUFFER* dataToSend = NULL;
CM_SIZE dataToSendSize = MAXLENGTH;
CM_ERROR error;
CM_SIZE sendBytesCount = 0;
FILE* f = fopen(fileStruct->filePath, "rb");
char buffer[2];
fseek(f, 0, SEEK_SET);
if (f == NULL)
{
perror((const char*)f);
}
char messageBuffer[10];
while (fread(buffer, 1, 1, f) == 1)
{
*(int*)messageBuffer = SENDTYPE;
messageBuffer[4] = buffer[0];
messageBuffer[5] = 0;
dataToSend = NULL;
error = CreateDataBuffer(&dataToSend, dataToSendSize);
if (CM_IS_ERROR(error))
{
_tprintf_s(TEXT("Failed to create SEND data buffer with err-code=0x%X!\n"), error);
DestroyClient(fileStruct->client);
UninitCommunicationModule();
return (DWORD)-1;
}
error = CopyDataIntoBuffer(dataToSend, (const CM_BYTE*)messageBuffer, (CM_SIZE)strlen(messageBuffer));
if (CM_IS_ERROR(error))
{
_tprintf_s(TEXT("CopyDataIntoBuffer failed with err-code=0x%X!\n"), error);
DestroyDataBuffer(dataToSend);
DestroyClient(fileStruct->client);
UninitCommunicationModule();
return (DWORD)-1;
}
error = SendDataToServer(fileStruct->client, dataToSend, &sendBytesCount);
if (CM_IS_ERROR(error))
{
_tprintf_s(TEXT("SendDataToServer failed with err-code=0x%X!\n"), error);
DestroyDataBuffer(dataToSend);
DestroyClient(fileStruct->client);
UninitCommunicationModule();
return (DWORD)-1;
}
DestroyDataBuffer(dataToSend);
}
return (DWORD)0;
}
Here is a part of code from Thread Server responsible for receiving data :
while ((error = ReceiveDataFromClient(newClient, receivedData, &numberOfBytesRead)) == 0)
{
message = (char*)receivedData->DataBuffer;
if (CM_IS_ERROR(error))
{
_tprintf_s(TEXT("ReceiveDataFormServer failed with err-code=0x%X!\n"), error);
DestroyDataBuffer(sendData);
DestroyDataBuffer(receivedData);
break;
}
type = *(int*)receivedData->DataBuffer;
printf("%x\n", type);
if (type == SENDTYPE)
{
printf("%c", (char)receivedData->DataBuffer[4]);
DestroyDataBuffer(receivedData);
receivedData = NULL;
error = CreateDataBuffer(&receivedData, MAXLENGTH);
if (CM_IS_ERROR(error))
{
_tprintf_s(TEXT("Creating receivedDataBuffer failed with err-code =0x%X!\n"), error);
UninitCommunicationModule();
}
continue;
}
This is ReceiveDataFromClient function:
CM_ERROR ReceiveDataFromClient(CM_SERVER_CLIENT* Client, CM_DATA_BUFFER* DataBufferToReceive, CM_SIZE* SuccessfullyReceivedBytesCount)
{
if (Client == NULL || DataBufferToReceive == NULL || SuccessfullyReceivedBytesCount == NULL)
return CM_INVALID_PARAMETER;
CM_ERROR error = ReceiveData(
Client->ClientConnection
, DataBufferToReceive->DataBuffer
, DataBufferToReceive->DataBufferSize
, SuccessfullyReceivedBytesCount
);
if (CM_IS_ERROR(error))
return error;
DataBufferToReceive->UsedBufferSize = *SuccessfullyReceivedBytesCount;
return error;
}
And this is ReceiveData function:
CM_ERROR ReceiveData(CM_CONNECTION* Connection, CM_BYTE* OutputDataBuffer, CM_SIZE OutputDataBufferSize, CM_SIZE* SuccessfullyReceivedBytesCount)
{
if (Connection == NULL)
return CM_INVALID_CONNECTION;
if (INVALID_SOCKET == Connection->ConnectionSocket)
return CM_INVALID_PARAMETER;
int receiveResult = recv(Connection->ConnectionSocket, (char*) OutputDataBuffer, OutputDataBufferSize, 0);
if (receiveResult == SOCKET_ERROR)
{
CM_LOG_ERROR(TEXT("recv failed with err-code=0x%X!"), WSAGetLastError());
return CM_CONNECTION_RECEIVE_FAILED;
}
if (receiveResult == 0)
return CM_CONNECTION_TERMINATED;
*SuccessfullyReceivedBytesCount = (CM_SIZE)receiveResult;
return CM_SUCCESS;
}