Merge r1758307, r1758308, r1758309, r1758311 from trunk:
mpm_winnt: remove 'data' AcceptFilter in favor of 'connect'
The 'data' AcceptFilter optimization instructs Windows to wait until data is received on a connection before completing the AcceptEx operation. Unfortunately, it seems this isn't performed atomically -- AcceptEx "partially" accepts the incoming connection during the wait for data, leaving all other incoming connections in the accept queue. This opens the server to a denial of service.
Since the fix for this requires a substantial rearchitecture (likely involving multiple outstanding calls to AcceptEx), disable the 'data' filter for now and replace it with 'connect', which uses the AcceptEx interface but does not wait for data.
Users running prior releases of httpd on Windows should explicitly move to a 'connect' AcceptFilter in their configurations if they are currently using the default 'data' filter.
Many thanks to mludha, Arthur Ramsey, Paul Spangler, and many others for their assistance in tracking down and diagnosing this issue.
mpm_winnt: remove the AcceptEx data network bucket
Follow-up to the prior commit: without an incoming data buffer, the custom network bucket code is now orphaned and we can remove it entirely. This has the added benefit that we are no longer using the internal OVERLAPPED.Pointer field, which is discouraged by the MSDN docs.
mpm_winnt: remove duplication of ap_process_connection
Further follow-up to the previous commit: now that we no longer patch a network bucket into the brigade, we can revert to calling ap_process_connection() directly instead of duplicating its logic.
docs: rebuild Submitted by: jchampion Reviewed/backported by: jim