NNG Release Notes

Release 1.3.0 (since 1.2.6)

Support for TLS 1.3 and external TLS providers. There is now an API whereby external “engines” can be developed for different TLS implementations. The first of these, for wolfSSL, is available. Set this with the NNG_TLS_ENGINE cmake option. The default is still to use Mbed TLS. The wolfSSL plugin is available under a different license (GPLv3 or commercial), and also provides support for TLS 1.3 and FIPS 140-2 capable solutions.
Message cloning and related performance improvements. This is not a feature, so much as a rather large improvement in terms of performance. All workloads will see some benefit — some will see substantial benefits.
Numerous other performance improvements. Much effort was made to reducing allocations, improving cache effectiveness, and eliminating extra context switches. This work is not yet done, but this is a big step in the right direction.
HTTP Server support for "non-exclusive" registration — a given handler may be registered as a fallback handler (e.g. for a directory), even if more specific handlers are registered.
Performance test programs grew more options to select different protocols and to change the URL to test across different transports.

Thread count is limited. Previously we would spawn potentially vast numbers of threads based on the number of available cores. By default we set an upper limit on this that is about 20 threads. Tune this with the NNG_MAX_TASKQ_WORKERS cmake option.
Raw mode fixes for XREQ and XRESPONDENT. These protocols used the raw mode inconsistently, leaving the header in the message body. This is corrected and the protocol headers are kept in the message headers. There is some small risk that some applications broken, but we are not aware of any that used RAW mode to parse message headers.
HTTP Server root URL handling had a few issues which are resolved.
Some platforms had difficult building due to inconsistencies in the handling of atomics.
Numerous test suites uncovered small (rare) races, etc. The tests themselves were often racy. Fixes to both NNG and the tests have been made, while increasing overall test coverage.
REP protocol with SENDFD was inconsistent (#1088).

Polyamorous Pair v1 mode is changed, such that a new API call is needed to use it. Further, this mode will likely be removed in a future release. Note that this mode also does not work with other implementations, nor does it support operation with nng_device().
Maximum hop count across nng_device() proxies is now limited to 15. This limit should be sufficient for all reasonable configurations, and forcing this allowed us to to inline the header for performance reasons.
The nng_msg_options support was removed. It was not used for anything.