for msvc abi builds, allow use of openssl libs from vcpkg

README.md

@@ -70,7 +70,11 @@ automatically detected.
 
 ### Windows MSVC
 
-On MSVC it's unfortunately not always a trivial process acquiring OpenSSL.
+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 precompiiled 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.
@@ -84,7 +88,24 @@ installation via an environment variable:
 set OPENSSL_DIR=C:\OpenSSL-Win64
 ```
 
-Note that this OpenSSL distribution does not ship with any root certificates.
+Now you will need to [install root certificates.](#acquiring-root-certificates)
+
+#### Installing OpenSSL 1.0.2 using vcpkg
+
+Install [vcpkg](https://github.com/Microsoft/vcpkg), and install the OpenSSL port like this:
+
+```Batchfile
+vcpkg install openssl:x64-windows
+set VCPKG_ROOT=c:\path\to\vcpkg\installation
+cargo build
+```
+
+For more information see the vcpkg build helper [documentation](http://docs.rs/vcpkg).
+To finsh setting up OpenSSL you will need to [install root certificates.](#acquiring-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`

appveyor.yml

@@ -20,10 +20,13 @@ environment:
       BITS: 32
       OPENSSL_VERSION: 1_0_2L
       OPENSSL_DIR: C:\OpenSSL
+    - TARGET: x86_64-pc-windows-msvc
+      VCPKG_DEFAULT_TRIPLET: x64-windows
 install:
   # install OpenSSL
-  - ps: Start-FileDownload "http://slproweb.com/download/Win${env:BITS}OpenSSL-${env:OPENSSL_VERSION}.exe"
-  - Win%BITS%OpenSSL-%OPENSSL_VERSION%.exe /SILENT /VERYSILENT /SP- /DIR="C:\OpenSSL"
+  - mkdir C:\OpenSSL
+  - ps: if (Test-Path env:OPENSSL_VERSION) { Start-FileDownload "http://slproweb.com/download/Win${env:BITS}OpenSSL-${env:OPENSSL_VERSION}.exe" }
+  - if defined OPENSSL_VERSION Win%BITS%OpenSSL-%OPENSSL_VERSION%.exe /SILENT /VERYSILENT /SP- /DIR="C:\OpenSSL"
   - appveyor DownloadFile https://curl.haxx.se/ca/cacert.pem -FileName C:\OpenSSL\cacert.pem
 
   # Install Rust
@@ -33,6 +36,10 @@ install:
   - if defined MSYS2 set PATH=C:\msys64\mingw%BITS%\bin;%PATH%
   - rustc -V
   - cargo -V
+  - if defined VCPKG_DEFAULT_TRIPLET git clone https://github.com/Microsoft/vcpkg c:\projects\vcpkg
+  - if defined VCPKG_DEFAULT_TRIPLET c:\projects\vcpkg\bootstrap-vcpkg.bat
+  - if defined VCPKG_DEFAULT_TRIPLET set VCPKG_ROOT=c:\projects\vcpkg
+  - if defined VCPKG_DEFAULT_TRIPLET %VCPKG_ROOT%\vcpkg.exe install openssl
 
 build: false
 

openssl-sys/Cargo.toml

@@ -18,6 +18,9 @@ libc = "0.2"
 pkg-config = "0.3.9"
 gcc = "0.3.42"
 
+[target.'cfg(target_env = "msvc")'.build-dependencies]
+vcpkg = "0.2"
+
 # We don't actually use metadeps for annoying reasons but this is still here for tooling
 [package.metadata.pkg-config]
 openssl = "1.0.1"

openssl-sys/build.rs

@@ -1,4 +1,6 @@
 extern crate pkg_config;
+#[cfg(target_env = "msvc")]
+extern crate vcpkg;
 extern crate gcc;
 
 use std::collections::HashSet;
@@ -98,6 +100,7 @@ fn find_openssl_dir(target: &str) -> OsString {
     }
 
     try_pkg_config();
+    try_vcpkg();
 
     let mut msg = format!("
 
@@ -213,6 +216,50 @@ fn try_pkg_config() {
     std::process::exit(0);
 }
 
+/// Attempt to find OpenSSL through vcpkg.
+///
+/// Note that if this succeeds then the function does not return as vcpkg
+/// should emit all of the cargo metadata that we need.
+#[cfg(target_env = "msvc")]
+fn try_vcpkg() {
+
+    // vcpkg will not emit any metadata if it can not find libraries
+    // appropriate for the target triple with the desired linkage.
+
+    let mut lib = vcpkg::Config::new()
+        .emit_includes(true)
+        .lib_name("libcrypto")
+        .lib_name("libssl")
+        .probe("openssl");
+
+    if let Err(e) = lib {
+        println!("note: vcpkg did not find openssl as libcrypto and libssl : {:?}",
+                 e);
+        lib = vcpkg::Config::new()
+            .emit_includes(true)
+            .lib_name("libeay32")
+            .lib_name("ssleay32")
+            .probe("openssl");
+    }
+    if let Err(e) = lib {
+        println!("note: vcpkg did not find openssl as ssleay32 and libeay32: {:?}",
+                 e);
+        return;
+    }
+
+    let lib = lib.unwrap();
+    validate_headers(&lib.include_paths);
+
+    println!("cargo:rustc-link-lib=user32");
+    println!("cargo:rustc-link-lib=gdi32");
+    println!("cargo:rustc-link-lib=crypt32");
+
+    std::process::exit(0);
+}
+
+#[cfg(not(target_env = "msvc"))]
+fn try_vcpkg() {}
+
 /// Validates the header files found in `include_dir` and then returns the
 /// version string of OpenSSL.
 fn validate_headers(include_dirs: &[PathBuf]) -> Version {