diff options
| -rw-r--r-- | net/tap-win32.c | 46 |
1 files changed, 36 insertions, 10 deletions
diff --git a/net/tap-win32.c b/net/tap-win32.c index 5e5d6db880..7fddb20b51 100644 --- a/net/tap-win32.c +++ b/net/tap-win32.c @@ -77,7 +77,12 @@ //#define DEBUG_TAP_WIN32 -#define TUN_ASYNCHRONOUS_WRITES 1 +/* FIXME: The asynch write path appears to be broken at + * present. WriteFile() ignores the lpNumberOfBytesWritten parameter + * for overlapped writes, with the result we return zero bytes sent, + * and after handling a single packet, receive is disabled for this + * interface. */ +/* #define TUN_ASYNCHRONOUS_WRITES 1 */ #define TUN_BUFFER_SIZE 1560 #define TUN_MAX_BUFFER_COUNT 32 @@ -461,27 +466,48 @@ static int tap_win32_write(tap_win32_overlapped_t *overlapped, BOOL result; DWORD error; +#ifdef TUN_ASYNCHRONOUS_WRITES result = GetOverlappedResult( overlapped->handle, &overlapped->write_overlapped, &write_size, FALSE); if (!result && GetLastError() == ERROR_IO_INCOMPLETE) WaitForSingleObject(overlapped->write_event, INFINITE); +#endif result = WriteFile(overlapped->handle, buffer, size, &write_size, &overlapped->write_overlapped); +#ifdef TUN_ASYNCHRONOUS_WRITES + /* FIXME: we can't sensibly set write_size here, without waiting + * for the IO to complete! Moreover, we can't return zero, + * because that will disable receive on this interface, and we + * also can't assume it will succeed and return the full size, + * because that will result in the buffer being reclaimed while + * the IO is in progress. */ +#error Async writes are broken. Please disable TUN_ASYNCHRONOUS_WRITES. +#else /* !TUN_ASYNCHRONOUS_WRITES */ if (!result) { - switch (error = GetLastError()) - { - case ERROR_IO_PENDING: -#ifndef TUN_ASYNCHRONOUS_WRITES - WaitForSingleObject(overlapped->write_event, INFINITE); -#endif - break; - default: - return -1; + error = GetLastError(); + if (error == ERROR_IO_PENDING) { + result = GetOverlappedResult(overlapped->handle, + &overlapped->write_overlapped, + &write_size, TRUE); } } +#endif + + if (!result) { +#ifdef DEBUG_TAP_WIN32 + LPTSTR msgbuf; + error = GetLastError(); + FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM, + NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), + &msgbuf, 0, NULL); + fprintf(stderr, "Tap-Win32: Error WriteFile %d - %s\n", error, msgbuf); + LocalFree(msgbuf); +#endif + return 0; + } return write_size; } |