Sending file via socket

Question

I have a problem with sending/receiving file via sockets. For example - In little video (440 Mb), throughout the video there is interference (green noise).

Why that is happening?

// server side
bool ClientThread::GetFile(char* path, LPDWORD fileSize, LPDWORD bytes)
{
    FileInfo* fileInfo = new FileInfo();
    if (!m_client->SyncGetRequest(fileInfo))
    {
        delete fileInfo;
        return false;
    }

    *fileSize = fileInfo->parts * fileInfo->partSize + fileInfo->remain;

    HANDLE hFile = CreateFile(path, GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    if (hFile == INVALID_HANDLE_VALUE)
    {
        printf("Creating file is failed!\n");
        delete fileInfo;
        return false;
    }
    HANDLE hMap = CreateFileMapping(hFile, NULL, PAGE_READWRITE, 0, *fileSize, 0);
    if (!hMap)
    {
        printf("Creating file mapping is failed!\n");
        CloseHandle(hFile);
        delete fileInfo;
        return false;
    }

    void* ptr = MapViewOfFile(hMap, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, *fileSize);
    if (!ptr)
    {
        printf("Map View of file has been failed!\n");
        CloseHandle(hMap);
        CloseHandle(hFile);
        delete fileInfo;
        return false;
    }

    for (int i = 0; i < fileInfo->parts; i++)
    {
        int received = m_client->SyncGetRequest((byte*)((DWORD)ptr + i * fileInfo->partSize), fileInfo->partSize);
        if (received != fileInfo->partSize)
            printf("WARNING! Byte mismatch detected! Part: %d\n", i + 1);

        if (received <= 0)
        {
            printf("File receiving is failed! Part: %d\n", i + 1);

            UnmapViewOfFile(ptr);
            CloseHandle(hMap);
            CloseHandle(hFile);

            delete fileInfo;
            return false;
        }
        *bytes += received;
    }

    if (fileInfo->remain > 0)
    {
        int received = m_client->SyncGetRequest((byte*)((DWORD)ptr + fileInfo->parts * fileInfo->partSize), fileInfo->remain);
        *bytes += received;
    }
    UnmapViewOfFile(ptr);

    CloseHandle(hMap);
    CloseHandle(hFile);
    delete fileInfo;
    printf("File successfully received!\n");
    return true;
}
// client side
void Client::SendFile(HANDLE hFile)
{
    DWORD partSize = 4096;
    DWORD size = GetFileSize(hFile, NULL);

    int parts = size / partSize;
    int remain = size - parts * partSize;

    FileInfo fInfo = { parts, partSize, remain };

    if (!SyncSendRequest(&fInfo))
        return;

    HANDLE hMap = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, 0);
    if (hMap)
    {
        void* ptr = MapViewOfFile(hMap, FILE_MAP_READ, 0, 0, 0);
        if (ptr)
        {
            for (int i = 0; i < parts; i++)
            {
                if (!SyncSendRequest((byte*)((DWORD)ptr + i * partSize), partSize))
                {
                    printf("Error sending file! Part: %d\n", i + 1);
                    break;
                }
            }

            if (remain > 0)
            {
                SyncSendRequest((byte*)((DWORD)ptr + parts * partSize), remain);
            }

            UnmapViewOfFile(ptr);
        }
        CloseHandle(hMap);
    }

    printf("File is sent!\n");
}

SyncSendData doing send and recv respond from/to server (1 byte)

SyncGetData doing recv and send respond from/to server (1 byte)

And size of received file matched with size of original file.

Answer 1

The problem as it turns out is not with the transfer protocol. But as evident from your screenshot you are using a windows media player window to run your video.

Try to install some video codecs and then see if the video plays correctly.

Another simple way to check for file validity is to perform a checksum on both sides. (They should be equal).

Regards.