WinDivert driver overhaul.

This is a major update designed to modernize the WinDivert driver, including
optimizations, design improvements and bug fixes.  The new version has not
been fully tested and should be considered **UNSTABLE**.

- Most of the packet processing is now (almost) fully out-of-band.  This is a
  good since the classify function runs at DISPATCH_LEVEL.  The driver will
  still try to match at least one packet before moving the work out-of-band.
- Re-injected non-matching packets are now clones rather than copies.
- Queued packets are still copied.  This is because the driver should avoid
  keeping a reference to the original packet for very long.  Since we do not
  trust the user application to handle the packet in a timely fashion, it is
  better to copy rather than keep a reference.  That said, the driver now
  implements an optimization where it will service a read request immediately
  if possible (saving 1 packet copy).
- SNIFF mode also now works differently.  Previously, SNIFF mode would not
  block the original packet.  However, this is problematic under the new
  design since WinDivert cannot permit the packet and retain a reference to it
  at the same time.  The new version will block & absorb the original packet
  and re-inject a clone out-of-band.
- Packet time management has been replaced.  Previously, a timer was used to
  periodically wake up a function that would sweep away expired packets.  The
  new version explicitly timestamps every packet, and expired packets are
  cleaned up by the read service routine.
- The context->filter is now deallocated in the destroy callback to avoid
  possible a race condition with the callout function.  It is unclear if this
  is really necessary, however.

This commit is contained in:

basil00

2017-10-10 23:14:37 +08:00

parent 910a2e3050

commit 2e1bfa8ca5

1 changed files with 545 additions and 382 deletions

sys/windivert.c

+545 -382

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