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[FIXED] EventLoop: Libuv may crash if connection destroyed while consuming#889

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kozlovic merged 1 commit into
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fix_888
Jul 22, 2025
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[FIXED] EventLoop: Libuv may crash if connection destroyed while consuming#889
kozlovic merged 1 commit into
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fix_888

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If the user destroys the connection while the read event was in progress it could be possible for the library to crash trying to process a read event.

We need to immediately stop polling when the read event is removed.

Changing also the way we retain the connection: we will now retain on the very first attach, and the adapters will have to call natsConnection_Destroy() when the event loop is fully detached.

Resolves #888

Signed-off-by: Ivan Kozlovic ivan@synadia.com

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Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 70.28%. Comparing base (5b12f90) to head (b89b44d).
Report is 11 commits behind head on main.

Files with missing lines Patch % Lines
src/conn.c 40.00% 2 Missing and 1 partial ⚠️
Additional details and impacted files
@@            Coverage Diff             @@
##             main     #889      +/-   ##
==========================================
+ Coverage   70.26%   70.28%   +0.01%     
==========================================
  Files          47       47              
  Lines       15560    15576      +16     
  Branches     3203     3209       +6     
==========================================
+ Hits        10934    10948      +14     
+ Misses       1547     1541       -6     
- Partials     3079     3087       +8     

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…uming

If the user destroys the connection while the read event was in progress
it could be possible for the library to crash trying to process a read
event.

We need to immediately stop polling when the read event is removed.

Changing also the way we retain the connection: we will now retain
on the very first attach, and the adapters will have to call
`natsConnection_Destroy()` when the event loop is fully detached.

Resolves #888

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

@derekcollison derekcollison left a comment

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LGTM

@kozlovic
kozlovic merged commit 665febe into main Jul 22, 2025
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@kozlovic
kozlovic deleted the fix_888 branch July 22, 2025 23:53
github-actions Bot pushed a commit that referenced this pull request Jul 22, 2025
kozlovic added a commit that referenced this pull request Sep 26, 2025
Release notes will be:

This release contains some breaking changes. See the "Changed" section below.

* Build
  * Disable NATS Streaming by default by @mtmk in #770
  * TLS
    * Require OpenSSL 1.1.1+ to compile. Removed the `NATS_BUILD_TLS_USE_OPENSSL_1_1_API` CMake variable by @kozlovic in #905
    * The option `natsOptions_SetSSLVerificationCallback` signature was changed to replace the use of `SSL_verify_cb` (which required OpenSSL dependency in the `nats.h` file), to the new callback `natsSSLVerifyCb`. See documentation of `natsSSLVerifyCb` to see the cast needed to compile with this new header file by @kozlovic in #908
* Modification of a `natsOptions` object if it has TLS/SSL configuration and is actively used by connections will now return a `NATS_ILLEGAL_STATE` by @kozlovic in #912

* Options
  * Ability to load the trusted CA certificates from a directory using the new option `natsOptions_LoadCATrustedCertificatesPath` by @kerbert101 in #862
  * Ability to connect via HTTP proxy for instance by adding a proxy connection handler using the new option `natsOptions_SetProxyConnHandler` by @wolfkor in #871 and @kozlovic in #897
  * Ability to load the certificate chain and key from a file on every connection attempt using the new option `natsOptions_LoadCertificatesChainDynamic` by @Matus-p in #901
  * Ability to perform concurrent TLS handshakes that may improve time it takes for concurrent connections to be established using the new option `natsOptions_AllowConcurrentTLSHandshakes ` by @kozlovic in #914. Issue was reported by @yanyongcheng in #899
* JetStream
  * Per-message TTL support (a NATS Server v2.11 feature) by @levb in #863
  * Pull consumer priority groups (a NATS Server v2.11 feature) by @levb in #869
* ObjectStore support by @kozlovic in #902. Thanks to @jfflynn41 and @alex1891 for the feedback in #876

* JetStream
  * Handling of publish asynchronous timeouts by @kozlovic in #886. Issue reported by @yanyongcheng in #880
* Timer insertion by @kozlovic in #883. Issue reported by @yanyongcheng in #881

* EventLoop:
  * Handling of possible failure on initial attach by @kozlovic in #918
  * LibEvent: `natsConnection_Close()` not closing the TCP connection by @kozlovic in #882. Issue was reported by @yanyongcheng in #879
  * Libuv: Possible crash if connection is destroyed while receiving data by @kozlovic in #889. Issue was reported by @yanyongcheng in #888
* KeyValue
  * Keys, History or watcher's next may incorrectly return `NATS_TIMEOUT` by @kozlovic in #917/ Issue was reported by @ArashPartow in #916
* MicroServices:
  * Wrong marshaling of `average_processing_time` by @kozlovic in #892. Issue was reported by @Archie3d in #890
  * Statistics error was always incremented by @kozlovic in #894. Issue was reported by @Archie3d in #893
* TLS
  * Unknown type name `SSL_verify_cb` by @kozlovic in #878. Issue was reported by @philipfoulkes in #877
  * Initialization and cleanup code related to OpenSSL was removed since it was deprecated for versions post OpenSSL 1.1. A cleanup function pertinent to 1.1+ code was possibly causing a problem. By @kozlovic in #905. Issue was reported by @vdeters in #904
  * Possible hang during handshake by @kozlovic in #907. Issue was reported by @etrochim in #906
  * Protect calls to `SSL_read` and `SSL_write` with a mutex. Since the same `SSL` object is shared between different threads, the OpenSSL library requires a mutex to be used by @kozlovic in #913
* Memory allocation check by @wooffie in #868
* Add missing status text string by @oldnick85 in #872 and @kozlovic in #874 (the issue was not present in any published release and was introduced in #869)
* Parsing of message headers with `NULL` or all-whitespace values by @habbbe in #873
* Removed some unused code related to handling of responses and added custom inbox with very long prefix test by @kozlovic in #885. Issue was reported by @yanyongcheng in #884
* Connection drain could cause missed reply and/or a 100ms delay by @kozlovic in #915. Issue was reported by @T-Maxxx in #911

* Build
  * Deprecated Ubuntu 20.04 in GitHub actions by @levb in #864
  * Removed the older compiler jobs by @levb in #865
  * Fixed Windows build to use the NATS Server main branch by @levb in #866

* @kerbert101 made their first contribution in #862
* @habbbe made their first contribution in #873
* @wolfkor made their first contribution in #871
* @Matus-p made their first contribution in #901

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>
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Successfully merging this pull request may close these issues.

Why is there no retain(nc) in the natsLibevent_Attach() function, and then a corresponding decrement in natsLibevent_Detach()?

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