[Proposal] Consider supporting OpenSSL 3, which is the default OpenSSL library on newer distros

[DarkmatterUAE]

I tried to setup a SimpleXMQ instance on a newly installed Debian 12 (bookworm) machine and was confused when it split out these error message:

root@debian:~# ./smp-server-ubuntu-20_04-x86-64 --help
./smp-server-ubuntu-20_04-x86-64: error while loading shared libraries: libcrypto.so.1.1: cannot open shared object file: No such file or directory

After a few digging, I found that file libcrypto.so.1.1 belongs to OpenSSL 1.1.1 shared library (package libssl1.1), but Debian 12 only provides OpenSSL 3 shared library ( package libssl3), which supplies libcrypto.so.3.

Since OpenSSL 1.1 already reached EOL in Sept. 11th, 2023, many distros have migrated to OpenSSL 3, so I guess it's sensible to use OpenSSL 3 by default instead of OpenSSL 1.1.

As a desperate measure (and an extremely ugly hack), it's actually possible to use OpenSSL 3 library without installing libssl1.1 (not available in Debian bookworm by default, unless you add a source entry of Debian bullseye (11)), by soft-linking /usr/lib/x86_64-linux-gnu/libcrypto.so.1.1 to /usr/lib/x86_64-linux-gnu/libcrypto.so.3, but apparantly no one should do that :)

root@debian:/usr/lib/x86_64-linux-gnu# ln -s libcrypto.so.3 libcrypto.so.1.1
root@debian:/usr/lib/x86_64-linux-gnu# ls -alh libcrypto*
lrwxrwxrwx 1 root root   14 May 30 13:19 libcrypto.so.1.1 -> libcrypto.so.3
-rw-r--r-- 1 root root 4.5M Oct 23  2023 libcrypto.so.3
root@debian:/usr/lib/x86_64-linux-gnu# cd
root@debian:~# ./smp-server-ubuntu-20_04-x86-64 --help
SMP server v5.7.5.0

Usage: smp-server-ubuntu-20_04-x86-64 [-v|--version] COMMAND

Available options:
  -h,--help                Show this help text
  -v,--version             Show version

Available commands:
  init                     Initialize server - creates /etc/opt/simplex and
                           /var/opt/simplex directories and configuration files
  cert                     Generate new online TLS server credentials
                           (configuration: /etc/opt/simplex/smp-server.ini)
  start                    Start server (configuration:
                           /etc/opt/simplex/smp-server.ini)
  delete                   Delete configuration and log files

[DarkmatterUAE]

Closing this issue due to SimpleX MQ project adding build target of Ubuntu 22.04, which uses OpenSSL 3 library. The problem mentioned in this issue has been solved.