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[Windows] Prevent socket callback from falsely detecting a connection close #578

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[Windows] Prevent socket callback from falsely detecting a connection close #578

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8 changes: 6 additions & 2 deletions src/event/event_windows.c
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Original file line number Diff line number Diff line change
Expand Up @@ -364,15 +364,19 @@ _dispatch_socket_callback(PTP_CALLBACK_INSTANCE inst, void *context,
} else if (lNetworkEvents & FD_READ) {
ioctlsocket(sock, FIONREAD, &dwBytesAvailable);
}
if (lNetworkEvents & FD_READ) {
// ioctlsocket could legally return 0 and that doesn't mean the socket is closed.
// Here and below we have to double-check dwBytesAvailable and make sure we don't
// wake up read/write handlers with 0 value for live (not closed) socket, because
// that would force handler to shut down.
if (((lNetworkEvents & FD_READ) && dwBytesAvailable > 0) || (lNetworkEvents & FD_CLOSE)) {
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This seems plausible to occur. But FD_READ is already set when FD_CLOSE is set, so this is rather confusing.

_dispatch_muxnote_retain(dmn);
if (!PostQueuedCompletionStatus(hPort, dwBytesAvailable,
(ULONG_PTR)DISPATCH_PORT_SOCKET_READ, (LPOVERLAPPED)dmn)) {
DISPATCH_INTERNAL_CRASH(GetLastError(),
"PostQueuedCompletionStatus");
}
}
if (lNetworkEvents & FD_WRITE) {
if (((lNetworkEvents & FD_WRITE) && dwBytesAvailable > 0) || (lNetworkEvents & FD_CLOSE)) {
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This doesn't make sense - dwBytesAavailable is guaranteed 1 if only a write event occurred. This condition doesn't seem correct. It should be either a write or a close event occurred I believe.

_dispatch_muxnote_retain(dmn);
if (!PostQueuedCompletionStatus(hPort, dwBytesAvailable,
(ULONG_PTR)DISPATCH_PORT_SOCKET_WRITE, (LPOVERLAPPED)dmn)) {
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