OpenSSL notes

Installation

OpenBSD (6.3)

• The pkg-config command comes with the OS.
• The OS comes with LibreSSL 2.7.2.
• The pkg-config --cflags --libs openssl command works out of the box and finds the system library.

NetBSD (7.1)

• The pkg-config command needs to be installed separately with sudo pkg_add pkgconf (or sudo pkg_add pkg-config).
• The OS comes with OpenSSL 1.0.1u.
• Even though the OS does not come with a pkg-config command, it does ship with an openssl.pc file, so once you install pkg-config the pkg-config --cflags --libs openssl finds the system library.
• However, the native OpenSSL 1.0.1 is older than the version 1.0.2 required by the Chicken egg. Users need to sudo pkg_add libressl or sudo pkg_add openssl from the OS package manager.
• After doing that, pkg-config --cflags --libs openssl points to the OpenSSL or LibreSSL version from the package manager, which automatically overrides the native version for this purpose.

FreeBSD (12.0) and DragonFlyBSD (5.6)

• The pkg-config command needs to be installed separately with sudo pkg install pkgconf.
• The OS comes with OpenSSL 1.1.1a-freebsd (FreeBSD) or LibreSSL 2.9.1 (DragonFly) but neither FreeBSD nor DragonFly ships with a complementary openssl.pc file for pkg-config.
• Therefore pkg-config --cflags --libs openssl still does not work.
• Easiest fix: tell people to sudo pkg install libressl or sudo pkg install openssl.
• Then pkg-config --cflags --libs openssl finds that copy of libressl or openssl.

MacOS (10.14 “Mojave”)

• The pkg-config command needs to be installed separately (Homebrew: brew install pkg-config).

• The OS comes with LibreSSL 2.6.5 but does not ship with an openssl.pc file. Also, the <openssl/ssl.h> and other necessary C header files may not be installed even though the shared library is.

• Easiest fix: tell people to use Homebrew to install an OpenSSL-compatible library: brew install openssl or brew install libressl.

• pkg-config --cflags --libs openssl does not work even when you have installed the separate package from Homebrew, because Homebrew packages don’t put their .pc files where pkg-config can find them.

• That can be remedied with:

  export PKG_CONFIG_PATH="$(brew --prefix openssl)/lib/pkgconfig"
  export PKG_CONFIG_PATH="$(brew --prefix libressl)/lib/pkgconfig"

• Then pkg-config --cflags --libs openssl finds that copy of libressl or openssl.

IMPORTANT: In many of the above cases, the openssl shell command can represent a different version of OpenSSL/LibreSSL than the library and headers found by pkg-config. So openssl should not be invoked to gather any version information in build scripts.