From 72bd8dbb86edf54117c5c062cbb93f2bc1f8b729 Mon Sep 17 00:00:00 2001 From: Guus Sliepen Date: Mon, 18 Jan 2016 13:58:46 +0100 Subject: [PATCH] Fix compatibility with TAP-Win32 9.0.0.21 and later. Tinc was a bit sloppy writing packets to the TAP-Win32 device using overlapped I/O. It worked with older versions of the driver, but it caused lots of dropped packets with newer versions of the driver (that use the NDIS 6 API). --- src/mingw/device.c | 62 +++++++++++++++++++++++++++++++++++++--------- 1 file changed, 50 insertions(+), 12 deletions(-) diff --git a/src/mingw/device.c b/src/mingw/device.c index 235e0fd..49b833a 100644 --- a/src/mingw/device.c +++ b/src/mingw/device.c @@ -43,11 +43,12 @@ static uint64_t device_total_in = 0; static uint64_t device_total_out = 0; extern char *myport; +OVERLAPPED r_overlapped; +OVERLAPPED w_overlapped; static DWORD WINAPI tapreader(void *bla) { int status; DWORD len; - OVERLAPPED overlapped; vpn_packet_t packet; int errors = 0; @@ -55,19 +56,17 @@ static DWORD WINAPI tapreader(void *bla) { /* Read from tap device and send to parent */ - overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); + r_overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); for(;;) { - overlapped.Offset = 0; - overlapped.OffsetHigh = 0; - ResetEvent(overlapped.hEvent); + ResetEvent(r_overlapped.hEvent); - status = ReadFile(device_handle, packet.data, MTU, &len, &overlapped); + status = ReadFile(device_handle, packet.data, MTU, &len, &r_overlapped); if(!status) { if(GetLastError() == ERROR_IO_PENDING) { - WaitForSingleObject(overlapped.hEvent, INFINITE); - if(!GetOverlappedResult(device_handle, &overlapped, &len, FALSE)) + WaitForSingleObject(r_overlapped.hEvent, INFINITE); + if(!GetOverlappedResult(device_handle, &r_overlapped, &len, FALSE)) continue; } else { logger(LOG_ERR, "Error while reading from %s %s: %s", device_info, @@ -201,6 +200,11 @@ static bool setup_device(void) { overwrite_mac = 1; } + /* Create overlapped events for tap I/O */ + + r_overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); + w_overlapped.hEvent = CreateEvent(NULL, TRUE, TRUE, NULL); + /* Start the tap reader */ thread = CreateThread(NULL, 0, tapreader, NULL, 0, NULL); @@ -235,14 +239,48 @@ static bool read_packet(vpn_packet_t *packet) { static bool write_packet(vpn_packet_t *packet) { DWORD lenout; - OVERLAPPED overlapped = {0}; + static vpn_packet_t queue; ifdebug(TRAFFIC) logger(LOG_DEBUG, "Writing packet of %d bytes to %s", packet->len, device_info); - if(!WriteFile(device_handle, packet->data, packet->len, &lenout, &overlapped)) { - logger(LOG_ERR, "Error while writing to %s %s: %s", device_info, device, winerror(GetLastError())); - return false; + /* Check if there is something in progress */ + + if(queue.len) { + DWORD size; + BOOL success = GetOverlappedResult(device_handle, &w_overlapped, &size, FALSE); + if(success) { + ResetEvent(&w_overlapped); + queue.len = 0; + } else { + int err = GetLastError(); + if(err != ERROR_IO_INCOMPLETE) { + ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error completing previously queued write: %s", winerror(err)); + ResetEvent(&w_overlapped); + queue.len = 0; + } else { + ifdebug(TRAFFIC) logger(LOG_DEBUG, "Previous overlapped write still in progress"); + // drop this packet + return true; + } + } + } + + /* Otherwise, try to write. */ + + memcpy(queue.data, packet->data, packet->len); + + if(!WriteFile(device_handle, queue.data, packet->len, &lenout, &w_overlapped)) { + int err = GetLastError(); + if(err != ERROR_IO_PENDING) { + logger(LOG_ERR, "Error while writing to %s %s: %s", device_info, device, winerror(err)); + return false; + } + // Write is being done asynchronously. + queue.len = packet->len; + } else { + // Write was completed immediately. + ResetEvent(&w_overlapped); } device_total_out += packet->len; -- 2.25.1