This commit is relatively major refactoring of the `openssl-sys` crate as well
as the `openssl` crate itself. The end goal here was to support OpenSSL 1.1.0,
and lots of other various tweaks happened along the way. The major new features
are:
* OpenSSL 1.1.0 is supported
* OpenSSL 0.9.8 is no longer supported (aka all OSX users by default)
* All FFI bindings are verified with the `ctest` crate (same way as the `libc`
crate)
* CI matrixes are vastly expanded to include 32/64 of all platforms, more
OpenSSL version coverage, as well as ARM coverage on Linux
* The `c_helpers` module is completely removed along with the `gcc` dependency.
* The `openssl-sys` build script was completely rewritten
* Now uses `OPENSSL_DIR` to find the installation, not include/lib env vars.
* Better error messages for mismatched versions.
* Better error messages for failing to find OpenSSL on a platform (more can be
done here)
* Probing of OpenSSL build-time configuration to inform the API of the `*-sys`
crate.
* Many Cargo features have been removed as they're now enabled by default.
As this is a breaking change to both the `openssl` and `openssl-sys` crates this
will necessitate a major version bump of both. There's still a few more API
questions remaining but let's hash that out on a PR!
Closes#452
GNU linkers will sometimes aggressively try to strip objects and archives from a
linker command line in a left-to-right fashion. When a linker hits an object
file that doesn't satisfy any unresolved symbols, it will discard the object and
not re-visit it. This means that currently if symbols are depended upon in
libssl then some of the dependencies of libssl (in libcrypto) may have already
been stripped, causing a link error.
By swapping the order of what's linked it reflects the natural flow of
dependencies and the linker should figure everything out for us.
The OpenSSL "SSL_OP_*" flags are in constant flux between different OpenSSL
versions. To avoid having to change the Rust definitions, we implement our
own numbering system in Rust, and use an automatically-generated C shim to
convert the bitflags at runtime.
Alex Crichton