OpenSSL bindings for Rust
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sfackler Merge pull request #974 from sfackler/shutdown
Add get_shutdown and set_shutdown
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This README does not correspond to rust-openssl 0.7.x or 0.8.x. See here for that README.


rust-openssl depends on OpenSSL version 1.0.1 or above, or LibreSSL. Both the libraries and headers need to be present in the build environment before this crate is compiled, and some instructions of how to do this are in the sections below.


openssl = { version = "0.10", features = ["vendored"] }

If the vendored Cargo feature is enabled, the openssl-src crate will be used to compile OpenSSL from source and statically link to it. OpenSSL version 1.1.0 is currently used, but that will be upgraded to 1.1.1 at some point after it is released without a major version bump to this crate.

This vendored copy will not be configured to automatically find the system's root certificates, but the openssl-probe crate can be used to do that instead.


On Linux, you can typically install OpenSSL via your package manager. The headers are sometimes provided in a separate package than the runtime libraries

  • look for something like openssl-devel or libssl-dev. You will also need the regular development utilities, like pkg-config, as the custom build script relies on them.
# On Debian and Ubuntu
sudo apt-get install pkg-config libssl-dev
# On Arch Linux
sudo pacman -S openssl
# On Fedora
sudo dnf install openssl-devel

If installation via a package manager is not possible, or if you're cross compiling to a separate target, you'll typically need to compile OpenSSL from source. That can normally be done with:

curl -O
tar xf openssl-1.1.0g.tar.gz
cd openssl-1.1.0g
export CC=...
./Configure --prefix=... linux-x86_64 -fPIC
make -j$(nproc)
make install


Although OpenSSL 0.9.8 is preinstalled on macOS this library is being phased out of macOS and this crate also does not support that version of OpenSSL. To use this crate on macOS you'll need to install OpenSSL via some alternate means, typically Homebrew:

brew install openssl

Occasionally an update of XCode or macOS will cause the linker to fail after compilation, to rectify this you may want to try and run:

xcode-select --install

If you're using latest version of Homebrew which supports --prefix command, OpenSSL will be automatically detected.

Windows MSVC

On MSVC it's unfortunately not always a trivial process acquiring OpenSSL. A couple of possibilities are downloading precompiled binaries for OpenSSL 1.1.0, or installing OpenSSL 1.0.2 using vcpkg.

Installing OpenSSL 1.1.0 using precompiled binaries

Perhaps the easiest way to do this right now is to download precompiled binaries and install them on your system. Currently it's recommended to install the 1.1.0 (non-light) installation if you're choosing this route.

Once a precompiled binary is installed you can configure this crate to find the installation via an environment variable:

set OPENSSL_DIR=C:\OpenSSL-Win64

During the installation process if you select "Copy OpenSSL DLLs to: The OpenSSL binaries (/bin) directory", you will need to add them to the PATH environment variable:

set PATH=%PATH%;C:\OpenSSL-Win64\bin

Now you will need to install root certificates.

Installing OpenSSL 1.0.2 using vcpkg

Install vcpkg, and install the OpenSSL port like this:

vcpkg install openssl:x64-windows
set VCPKG_ROOT=c:\path\to\vcpkg\installation
cargo build

For more information see the vcpkg build helper documentation. To finish setting up OpenSSL you will need to install root certificates.

Acquiring Root Certificates

Neither of the above OpenSSL distributions ship with any root certificates. So to make requests to servers on the internet, you have to install them manually. Download the cacert.pem file from here, copy it somewhere safe (C:\OpenSSL-Win64\certs is a good place) and point the SSL_CERT_FILE environment variable there:

set SSL_CERT_FILE=C:\OpenSSL-Win64\certs\cacert.pem

After that, you're just a cargo build away!

Windows GNU (MinGW)

The easiest way to acquire OpenSSL when working with MinGW is to ensure you're using MSYS2 and to then execute:

# 32-bit
pacman -S mingw-w64-i686-openssl

# 64-bit
pacman -S mingw-w64-x86_64-openssl

And after that, a cargo build should be all you need!

Manual configuration

rust-openssl's build script will by default attempt to locate OpenSSL via pkg-config or other system-specific mechanisms. This will not work in some situations however, for example cross compiling or when using a copy of OpenSSL other than the normal system install.

The build script can be configured via environment variables:

  • OPENSSL_DIR - If specified, a directory that will be used to find OpenSSL installation. It's expected that under this directory the include folder has header files and a lib folder has the runtime libraries.
  • OPENSSL_LIB_DIR - If specified, a directory that will be used to find OpenSSL libraries. Overrides the lib folder implied by OPENSSL_DIR (if specified).
  • OPENSSL_INCLUDE_DIR - If specified, a directory that will be used to find OpenSSL header files. Overrides the include folder implied by OPENSSL_DIR (if specified).
  • OPENSSL_STATIC - If specified, OpenSSL libraries will be statically rather than dynamically linked.
  • OPENSSL_LIBS - If specified, the names of the OpenSSL libraries that will be linked, e.g. ssl:crypto.

If OPENSSL_DIR or OPENSSL_LIB_DIR and OPENSSL_INCLUDE_DIR is specified, then the build script will skip the pkg-config step.

For target-specific configuration, each of these environment variables can be prefixed by an upper-cased target, for example, X86_64_UNKNOWN_LINUX_GNU_OPENSSL_DIR. This can be useful in cross compilation contexts.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed under the terms of both the Apache License, Version 2.0 and the MIT license without any additional terms or conditions.