[OpenSIPS-Devel] [OpenSIPS/opensips] e5b231: clusterer: Fix sync edge-case causing SHM accumula...

[Liviu Chircu]

  Branch: refs/heads/master
  Home:   https://github.com/OpenSIPS/opensips
  Commit: e5b2317ca9e9f33baef29205ecd792d8a5d5d2ed
      https://github.com/OpenSIPS/opensips/commit/e5b2317ca9e9f33baef29205ecd792d8a5d5d2ed
  Author: Liviu Chircu <liviu at opensips.org>
  Date:   2024-10-24 (Thu, 24 Oct 2024)

  Changed paths:
    M modules/clusterer/sync.c

  Log Message:
  -----------
  clusterer: Fix sync edge-case causing SHM accumulation

This patch fixes a specific sync sequence leading to indefinite
accumulation of BIN packets and SHM exhaustion, as follows:

1) Sync Receiver node times out the sync in sync_check_timer()
    (default timeout is 5s, by no means difficult to achieve)
2) Sync Donor continues to send SYNC packets
    (on Receiver side, cap state is updated: PROGRESSING)
3) ! Sync Donor node loses link-state mid-sync, due to the pings being
    on the same TCP connection (and delayed, way in the back)
4) Sync Donor fails & drops remaining SYNC + SYNC-END packets, as link
    is down.  Due to this, the handle_sync_end(!is_timeout) procedure
    is never ran on the Receiver, so the PROGRESSING flag is never
    removed -> indefinite SHM buffering / memory leak

Thanks to Răzvan Crainea for helping with code & troubleshooting here!



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