netcat源代码分析(4)doexec.c文件中的SessionWriteShellThreadFn ()函数

// **********************************************************************
// SessionWriteShellThreadFn
//
// The write thread procedure. Reads from socket, writes to pipe connected
// to shell process.  


static VOID
SessionWriteShellThreadFn(
    LPVOID Parameter
    )
{
    PSESSION_DATA Session = Parameter;
    BYTE    RecvBuffer[1];
    BYTE    Buffer[BUFFER_SIZE];
    DWORD   BytesWritten;
    DWORD   BufferCnt;

    BufferCnt = 0;

    //
    // Loop, reading one byte at a time from the socket.    
    //
    while (recv(Session->ClientSocket, RecvBuffer, sizeof(RecvBuffer), 0) != 0) {

        Buffer[BufferCnt++] = RecvBuffer[0];
        if (RecvBuffer[0] == '\r')
                Buffer[BufferCnt++] = '\n';


        // Trap exit as it causes problems
        if (strnicmp(Buffer, "exit\r\n", 6) == 0)        //注意，如果接受到exit回车，则结束。
            ExitThread(0);


        //
        // If we got a CR, it's time to send what we've buffered up down to the
        // shell process.
        // SECURITY FIX: CW 12/27/04 Add BufferCnt size check.  If we hit end of buffer, flush it
        if (RecvBuffer[0] == '\n' || RecvBuffer[0] == '\r' || BufferCnt > BUFFER_SIZE-1) {
            if (! WriteFile(Session->WritePipeHandle, Buffer, BufferCnt,
                            &BytesWritten, NULL))
            {
                break;
            }
            BufferCnt = 0;
        }
    }

    ExitThread(0);
}