childsession.c

 
#include "tcp.h"
 
#include <winpr/library.h>
#include <winpr/assert.h>
#include <winpr/print.h>
#include <winpr/sysinfo.h>
 
#include <freerdp/utils/ringbuffer.h>
 
#include "childsession.h"
 
#define TAG FREERDP_TAG("childsession")
 
typedef struct
{
  OVERLAPPED readOverlapped;
  HANDLE hFile;
  BOOL opInProgress;
  BOOL lastOpClosed;
  RingBuffer readBuffer;
  BOOL blocking;
  BYTE tmpReadBuffer[4096];
 
  HANDLE readEvent;
} WINPR_BIO_NAMED;
 
static int transport_bio_named_uninit(BIO* bio);
 
static int transport_bio_named_write(BIO* bio, const char* buf, int size)
{
  WINPR_ASSERT(bio);
  WINPR_ASSERT(buf);
 
  WINPR_BIO_NAMED* ptr = (WINPR_BIO_NAMED*)BIO_get_data(bio);
 
  if (!buf)
    return 0;
 
  BIO_clear_flags(bio, BIO_FLAGS_WRITE);
  DWORD written = 0;
 
  const UINT64 start = GetTickCount64();
  BOOL ret =
      WriteFile(ptr->hFile, buf, WINPR_ASSERTING_INT_CAST(uint32_t, size), &written, nullptr);
  // winpr_HexDump(TAG, WLOG_DEBUG, buf, size);
 
  if (!ret)
  {
    WLog_VRB(TAG, "error or deferred");
    return 0;
  }
 
  WLog_VRB(TAG, "(%d)=%d written=%" PRIu32 " duration=%" PRIu64, size, ret, written,
           GetTickCount64() - start);
 
  if (written == 0)
  {
    WLog_VRB(TAG, "closed on write");
    return 0;
  }
 
  WINPR_ASSERT(written <= INT32_MAX);
  return (int)written;
}
 
static BOOL treatReadResult(WINPR_BIO_NAMED* ptr, DWORD readBytes)
{
  WLog_VRB(TAG, "treatReadResult(readBytes=%" PRIu32 ")", readBytes);
  ptr->opInProgress = FALSE;
  if (readBytes == 0)
  {
    WLog_VRB(TAG, "readBytes == 0");
    return TRUE;
  }
 
  if (!ringbuffer_write(&ptr->readBuffer, ptr->tmpReadBuffer, readBytes))
  {
    WLog_VRB(TAG, "ringbuffer_write()");
    return FALSE;
  }
 
  return SetEvent(ptr->readEvent);
}
 
static BOOL doReadOp(WINPR_BIO_NAMED* ptr)
{
  DWORD readBytes = 0;
 
  if (!ResetEvent(ptr->readEvent))
    return FALSE;
 
  ptr->opInProgress = TRUE;
  if (!ReadFile(ptr->hFile, ptr->tmpReadBuffer, sizeof(ptr->tmpReadBuffer), &readBytes,
                &ptr->readOverlapped))
  {
    DWORD error = GetLastError();
    switch (error)
    {
      case ERROR_NO_DATA:
        WLog_VRB(TAG, "No Data, unexpected");
        return TRUE;
      case ERROR_IO_PENDING:
        WLog_VRB(TAG, "ERROR_IO_PENDING");
        return TRUE;
      case ERROR_BROKEN_PIPE:
        WLog_VRB(TAG, "broken pipe");
        ptr->lastOpClosed = TRUE;
        return TRUE;
      default:
        return FALSE;
    }
  }
 
  return treatReadResult(ptr, readBytes);
}
 
static int transport_bio_named_read(BIO* bio, char* buf, int size)
{
  WINPR_ASSERT(bio);
  WINPR_ASSERT(buf);
 
  WINPR_BIO_NAMED* ptr = (WINPR_BIO_NAMED*)BIO_get_data(bio);
  if (!buf)
    return 0;
 
  BIO_clear_flags(bio, BIO_FLAGS_SHOULD_RETRY | BIO_FLAGS_READ);
 
  if (ptr->blocking)
  {
    while (!ringbuffer_used(&ptr->readBuffer))
    {
      if (ptr->lastOpClosed)
        return 0;
 
      if (ptr->opInProgress)
      {
        DWORD status = WaitForSingleObjectEx(ptr->readEvent, 500, TRUE);
        switch (status)
        {
          case WAIT_TIMEOUT:
          case WAIT_IO_COMPLETION:
            continue;
          case WAIT_OBJECT_0:
            break;
          default:
            return -1;
        }
 
        DWORD readBytes = 0;
        if (!GetOverlappedResult(ptr->hFile, &ptr->readOverlapped, &readBytes, FALSE))
        {
          WLog_ERR(TAG, "GetOverlappedResult blocking(lastError=%" PRIu32 ")",
                   GetLastError());
          return -1;
        }
 
        if (!treatReadResult(ptr, readBytes))
        {
          WLog_ERR(TAG, "treatReadResult blocking");
          return -1;
        }
      }
    }
  }
  else
  {
    if (ptr->opInProgress)
    {
      DWORD status = WaitForSingleObject(ptr->readEvent, 0);
      switch (status)
      {
        case WAIT_OBJECT_0:
          break;
        case WAIT_TIMEOUT:
          BIO_set_flags(bio, (BIO_FLAGS_SHOULD_RETRY | BIO_FLAGS_READ));
          return -1;
        default:
          WLog_ERR(TAG, "error WaitForSingleObject(readEvent)=0x%" PRIx32 "", status);
          return -1;
      }
 
      DWORD readBytes = 0;
      if (!GetOverlappedResult(ptr->hFile, &ptr->readOverlapped, &readBytes, FALSE))
      {
        WLog_ERR(TAG, "GetOverlappedResult non blocking(lastError=%" PRIu32 ")",
                 GetLastError());
        return -1;
      }
 
      if (!treatReadResult(ptr, readBytes))
      {
        WLog_ERR(TAG, "error treatReadResult non blocking");
        return -1;
      }
    }
  }
 
  SSIZE_T ret = -1;
  if (size >= 0)
  {
    size_t rsize = ringbuffer_used(&ptr->readBuffer);
    if (rsize <= SSIZE_MAX)
      ret = MIN(size, (SSIZE_T)rsize);
  }
  if ((size >= 0) && ret)
  {
    DataChunk chunks[2] = WINPR_C_ARRAY_INIT;
    const int nchunks =
        ringbuffer_peek(&ptr->readBuffer, chunks, WINPR_ASSERTING_INT_CAST(size_t, ret));
    for (int i = 0; i < nchunks; i++)
    {
      memcpy(buf, chunks[i].data, chunks[i].size);
      buf += chunks[i].size;
    }
 
    ringbuffer_commit_read_bytes(&ptr->readBuffer, WINPR_ASSERTING_INT_CAST(size_t, ret));
 
    WLog_VRB(TAG, "(%d)=%" PRIdz " nchunks=%d", size, ret, nchunks);
  }
 
  if (!ringbuffer_used(&ptr->readBuffer))
  {
    if (!ptr->opInProgress && !doReadOp(ptr))
    {
      WLog_ERR(TAG, "error rearming read");
      return -1;
    }
  }
 
  if (ret <= 0)
    BIO_set_flags(bio, (BIO_FLAGS_SHOULD_RETRY | BIO_FLAGS_READ));
 
  WINPR_ASSERT(ret <= INT32_MAX);
  return (int)ret;
}
 
static int transport_bio_named_puts(BIO* bio, const char* str)
{
  WINPR_ASSERT(bio);
  WINPR_ASSERT(str);
 
  const size_t max = (INT_MAX > SIZE_MAX) ? SIZE_MAX : INT_MAX;
  const size_t len = strnlen(str, max);
  if (len >= max)
    return -1;
  return transport_bio_named_write(bio, str, WINPR_ASSERTING_INT_CAST(int, len));
}
 
static int transport_bio_named_gets(BIO* bio, char* str, int size)
{
  WINPR_ASSERT(bio);
  WINPR_ASSERT(str);
 
  return transport_bio_named_read(bio, str, size);
}
 
static long transport_bio_named_ctrl(BIO* bio, int cmd, long arg1, void* arg2)
{
  WINPR_ASSERT(bio);
 
  int status = -1;
  WINPR_BIO_NAMED* ptr = (WINPR_BIO_NAMED*)BIO_get_data(bio);
 
  switch (cmd)
  {
    case BIO_C_SET_SOCKET:
    case BIO_C_GET_SOCKET:
      return -1;
    case BIO_C_GET_EVENT:
      if (!BIO_get_init(bio) || !arg2)
        return 0;
 
      *((HANDLE*)arg2) = ptr->readEvent;
      return 1;
    case BIO_C_SET_HANDLE:
      BIO_set_init(bio, 1);
      if (!BIO_get_init(bio) || !arg2)
        return 0;
 
      ptr->hFile = (HANDLE)arg2;
      ptr->blocking = TRUE;
      if (!doReadOp(ptr))
        return -1;
      return 1;
    case BIO_C_SET_NONBLOCK:
    {
      WLog_DBG(TAG, "BIO_C_SET_NONBLOCK");
      ptr->blocking = FALSE;
      return 1;
    }
    case BIO_C_WAIT_READ:
    {
      WLog_DBG(TAG, "BIO_C_WAIT_READ");
      return 1;
    }
 
    case BIO_C_WAIT_WRITE:
    {
      WLog_DBG(TAG, "BIO_C_WAIT_WRITE");
      return 1;
    }
 
    default:
      break;
  }
 
  switch (cmd)
  {
    case BIO_CTRL_GET_CLOSE:
      status = BIO_get_shutdown(bio);
      break;
 
    case BIO_CTRL_SET_CLOSE:
      BIO_set_shutdown(bio, (int)arg1);
      status = 1;
      break;
 
    case BIO_CTRL_DUP:
      status = 1;
      break;
 
    case BIO_CTRL_FLUSH:
      status = 1;
      break;
 
    default:
      status = 0;
      break;
  }
 
  return status;
}
 
static void BIO_NAMED_free(WINPR_BIO_NAMED* ptr)
{
  if (!ptr)
    return;
 
  if (ptr->hFile)
  {
    (void)CloseHandle(ptr->hFile);
    ptr->hFile = nullptr;
  }
 
  if (ptr->readEvent)
  {
    (void)CloseHandle(ptr->readEvent);
    ptr->readEvent = nullptr;
  }
 
  ringbuffer_destroy(&ptr->readBuffer);
  free(ptr);
}
 
static int transport_bio_named_uninit(BIO* bio)
{
  WINPR_ASSERT(bio);
  WINPR_BIO_NAMED* ptr = (WINPR_BIO_NAMED*)BIO_get_data(bio);
 
  BIO_NAMED_free(ptr);
 
  BIO_set_init(bio, 0);
  BIO_set_flags(bio, 0);
  return 1;
}
 
static int transport_bio_named_new(BIO* bio)
{
  WINPR_ASSERT(bio);
 
  WINPR_BIO_NAMED* ptr = (WINPR_BIO_NAMED*)calloc(1, sizeof(WINPR_BIO_NAMED));
  if (!ptr)
    return 0;
 
  if (!ringbuffer_init(&ptr->readBuffer, 0xfffff))
    goto error;
 
  ptr->readEvent = CreateEventA(nullptr, TRUE, FALSE, nullptr);
  if (!ptr->readEvent || ptr->readEvent == INVALID_HANDLE_VALUE)
    goto error;
 
  ptr->readOverlapped.hEvent = ptr->readEvent;
 
  BIO_set_data(bio, ptr);
  BIO_set_flags(bio, BIO_FLAGS_SHOULD_RETRY);
  return 1;
 
error:
  BIO_NAMED_free(ptr);
  return 0;
}
 
static int transport_bio_named_free(BIO* bio)
{
  WINPR_BIO_NAMED* ptr = nullptr;
 
  if (!bio)
    return 0;
 
  transport_bio_named_uninit(bio);
 
  ptr = (WINPR_BIO_NAMED*)BIO_get_data(bio);
  if (ptr)
    BIO_set_data(bio, nullptr);
 
  return 1;
}
 
static BIO_METHOD* BIO_s_namedpipe(void)
{
  static BIO_METHOD* bio_methods = nullptr;
 
  if (bio_methods == nullptr)
  {
    if (!(bio_methods = BIO_meth_new(BIO_TYPE_NAMEDPIPE, "NamedPipe")))
      return nullptr;
 
    BIO_meth_set_write(bio_methods, transport_bio_named_write);
    BIO_meth_set_read(bio_methods, transport_bio_named_read);
    BIO_meth_set_puts(bio_methods, transport_bio_named_puts);
    BIO_meth_set_gets(bio_methods, transport_bio_named_gets);
    BIO_meth_set_ctrl(bio_methods, transport_bio_named_ctrl);
    BIO_meth_set_create(bio_methods, transport_bio_named_new);
    BIO_meth_set_destroy(bio_methods, transport_bio_named_free);
  }
 
  return bio_methods;
}
 
typedef NTSTATUS (*WinStationCreateChildSessionTransportFn)(WCHAR* path, DWORD len);
static BOOL createChildSessionTransport(HANDLE* pFile)
{
  WINPR_ASSERT(pFile);
 
  HANDLE hModule = nullptr;
  BOOL ret = FALSE;
  *pFile = INVALID_HANDLE_VALUE;
 
  BOOL childEnabled = 0;
  if (!WTSIsChildSessionsEnabled(&childEnabled))
  {
    WLog_ERR(TAG, "error when calling WTSIsChildSessionsEnabled");
    goto out;
  }
 
  if (!childEnabled)
  {
    WLog_INFO(TAG, "child sessions aren't enabled");
    if (!WTSEnableChildSessions(TRUE))
    {
      WLog_ERR(TAG, "error when calling WTSEnableChildSessions");
      goto out;
    }
    WLog_INFO(TAG, "successfully enabled child sessions");
  }
 
  hModule = LoadLibraryA("winsta.dll");
  if (!hModule)
    return FALSE;
 
  {
    WCHAR pipePath[0x80] = WINPR_C_ARRAY_INIT;
    char pipePathA[0x80] = WINPR_C_ARRAY_INIT;
 
    {
      WinStationCreateChildSessionTransportFn createChildSessionFn =
          GetProcAddressAs(hModule, "WinStationCreateChildSessionTransport",
                           WinStationCreateChildSessionTransportFn);
      if (!createChildSessionFn)
      {
        WLog_ERR(TAG, "unable to retrieve WinStationCreateChildSessionTransport function");
        goto out;
      }
 
      {
        HRESULT hStatus = createChildSessionFn(pipePath, 0x80);
        if (!SUCCEEDED(hStatus))
        {
          WLog_ERR(TAG, "error 0x%08x when creating childSessionTransport",
                   WINPR_CXX_COMPAT_CAST(unsigned, hStatus));
          goto out;
        }
      }
    }
 
    {
      const BYTE startOfPath[] = { '\\', 0, '\\', 0, '.', 0, '\\', 0 };
      if (_wcsncmp(pipePath, (const WCHAR*)startOfPath, 4))
      {
        /* when compiled under 32 bits, the path may miss "\\.\" at the beginning of the
         * string so add it if it's not there
         */
        size_t len = _wcslen(pipePath);
        if (len > 0x80 - (4 + 1))
        {
          WLog_ERR(TAG, "pipePath is too long to be adjusted");
          goto out;
        }
 
        memmove(pipePath + 4, pipePath, (len + 1) * sizeof(WCHAR));
        memcpy(pipePath, startOfPath, 8);
      }
    }
 
    (void)ConvertWCharNToUtf8(pipePath, 0x80, pipePathA, sizeof(pipePathA));
    WLog_DBG(TAG, "child session is at '%s'", pipePathA);
 
    {
      HANDLE f = CreateFileW(pipePath, GENERIC_READ | GENERIC_WRITE, 0, nullptr,
                             OPEN_EXISTING, FILE_FLAG_OVERLAPPED, nullptr);
      if (f == INVALID_HANDLE_VALUE)
      {
        WLog_ERR(TAG, "error when connecting to local named pipe");
        goto out;
      }
 
      *pFile = f;
    }
  }
 
  ret = TRUE;
 
out:
  FreeLibrary(hModule);
  return ret;
}
 
BIO* createChildSessionBio(void)
{
  HANDLE f = INVALID_HANDLE_VALUE;
  if (!createChildSessionTransport(&f))
    return nullptr;
 
  BIO* lowLevelBio = BIO_new(BIO_s_namedpipe());
  if (!lowLevelBio)
  {
    (void)CloseHandle(f);
    return nullptr;
  }
 
  BIO_set_handle(lowLevelBio, f);
  BIO* bufferedBio = BIO_new(BIO_s_buffered_socket());
 
  if (!bufferedBio)
  {
    BIO_free_all(lowLevelBio);
    return nullptr;
  }
 
  bufferedBio = BIO_push(bufferedBio, lowLevelBio);
 
  return bufferedBio;
}