Drop support for OpenSSL pre-1.1.1

[eboasson]

OpenSSL versions older than 1.1.1 have all been dead for over 4 years. I don't see why an Cyclone would have to continue supporting the bad practice of not updating EOL'd security sensitive libraries full of known vulnerabilities.

Of course nobody should be using OpenSSL 1.1.1 anymore (it has been EOL'd about half a year ago), but I know there are still plenty of systems in the field that rely on it and even the CI on Azure gets the latest Linux images with it pre-installed.

Fixes #1925 — or so I expect anyway. @zhzhzoo-autra I'd appreciate it if you could give it a try.

[dpotman]

Looks good! In the readme there is a reference to OpenSSL 1.1, that line also needs an update:

cyclonedds/README.md

Line 117 in 2246c00

* Optionally [OpenSSL](https://www.openssl.org/), preferably version 1.1;

And here:

cyclonedds/docs/dev/dds_security_effort.md

Line 140 in 2246c00

However, it expects (or at least it's preferred to have) version 1.1 or newer,

[eboasson]

Looks good! In the readme there is a reference to OpenSSL 1.1, that line also needs an update:

cyclonedds/README.md

Line 117 in 2246c00

* Optionally [OpenSSL](https://www.openssl.org/), preferably version 1.1;

And here:

cyclonedds/docs/dev/dds_security_effort.md

Line 140 in 2246c00

However, it expects (or at least it's preferred to have) version 1.1 or newer,

Done. I also had to solve some conflicts because of merging #1826 and force-pushing it seemed the most sensible solution.

[zhzhzoo-autra]

Thanks for your attention! I tried to compile with boringssl with this patch, the compile errors disappeared, but there's a linker error:

bazel-out/k8-opt/bin/external/cyclonedds/_objs/cyclonedds/ddsi_ssl.pic.o:ddsi_ssl.c:function ddsi_ssl_accept: error: undefined reference to 'BIO_do_accept'
collect2: error: ld returned 1 exit status

I thinks it's because boringssl removed some of openssl's api. I have no understanding of Openssl so I don't know if this if a big or small problem...

[eboasson]

Thanks for your attention! I tried to compile with boringssl with this patch, the compile errors disappeared, but there's a linker error:

bazel-out/k8-opt/bin/external/cyclonedds/_objs/cyclonedds/ddsi_ssl.pic.o:ddsi_ssl.c:function ddsi_ssl_accept: error: undefined reference to 'BIO_do_accept'
collect2: error: ld returned 1 exit status

I thinks it's because boringssl removed some of openssl's api. I have no understanding of Openssl so I don't know if this if a big or small problem...

Thanks for trying it!

The easiest way to work around this would be to just not include the TCP / TCP+TLS support code (hardly anyone uses it anyway). There is not a separate build option to do that, by I think there should be, so: #1953. If you can give that a whirl after doing cmake -DENABLE_TCP_TLS=0 ...

The real solution is of course to see what BIO_do_accept maps to in boringssl. I'm sure it is straightforward.