curl: Add HTTP/2 support with nghttp2

Compilation against openssl is forced if `--with-nghttp2` is specified
and `--with-libressl` is omitted, because the default `--with-darwinssl`
(Secure Transport) lacks support for ALPN which is necessary to negotiate
HTTP/2 over TLS encrypted connections.

Also fixed a problem where `--with-libressl` was ignored on Lion.

More info:
* [cURL HTTP/2 Support](http://curl.haxx.se/dev/readme-http2.html)
* [cURL ALPN Support](http://curl.haxx.se/docs/ssl-compared.html)

Closes #37979.
Closes #36942.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

1 files changed, 14 insertions, 9 deletions

diff --git a/Library/Formula/curl.rb b/Library/Formula/curl.rb
index 33129f075..a20d2db1f 100644
--- a/Library/Formula/curl.rb
+++ b/Library/Formula/curl.rb
@@ -3,6 +3,7 @@ class Curl < Formula
   url "http://curl.haxx.se/download/curl-7.41.0.tar.bz2"
   mirror "http://ftp.sunet.se/pub/www/utilities/curl/curl-7.41.0.tar.bz2"
   sha256 "9f8b546bdc5c57d959151acae7ce6610fe929d82b8d0fc5b25a3a2296e5f8bea"
+  revision 1
 
   bottle do
     cellar :any
@@ -20,17 +21,20 @@ class Curl < Formula
   option "with-gssapi", "Build with GSSAPI/Kerberos authentication support."
   option "with-libmetalink", "Build with libmetalink support."
   option "with-libressl", "Build with LibreSSL instead of Secure Transport or OpenSSL"
+  option "with-nghttp2", "Build with HTTP/2 support (requires OpenSSL or LibreSSL)"
 
   deprecated_option "with-idn" => "with-libidn"
   deprecated_option "with-rtmp" => "with-rtmpdump"
   deprecated_option "with-ssh" => "with-libssh2"
   deprecated_option "with-ares" => "with-c-ares"
 
-  if MacOS.version >= :mountain_lion
+  # HTTP/2 support requires OpenSSL 1.0.2+ or LibreSSL 2.1.3+ for ALPN Support
+  # which is currently not supported by Secure Transport (DarwinSSL).
+  if MacOS.version < :mountain_lion || (build.with?("nghttp2") && build.without?("libressl"))
+    depends_on "openssl"
+  else
     option "with-openssl", "Build with OpenSSL instead of Secure Transport"
     depends_on "openssl" => :optional
-  else
-    depends_on "openssl"
   end
 
   depends_on "pkg-config" => :build
@@ -40,6 +44,7 @@ class Curl < Formula
   depends_on "c-ares" => :optional
   depends_on "libmetalink" => :optional
   depends_on "libressl" => :optional
+  depends_on "nghttp2" => :optional
 
   def install
     # Throw an error if someone actually tries to rock both SSL choices.
@@ -47,7 +52,7 @@ class Curl < Formula
     if build.with?("libressl") && build.with?("openssl")
       ohai <<-EOS.undent
       --with-openssl and --with-libressl are both specified and
-      curl can only use one at a time; proceeding with openssl.
+      curl can only use one at a time; proceeding with libressl.
       EOS
     end
 
@@ -61,14 +66,14 @@ class Curl < Formula
     # cURL has a new firm desire to find ssl with PKG_CONFIG_PATH instead of using
     # "--with-ssl" any more. "when possible, set the PKG_CONFIG_PATH environment
     # variable instead of using this option". Multi-SSL choice breaks w/o using it.
-    if MacOS.version < :mountain_lion || build.with?("openssl")
-      ENV.prepend_path "PKG_CONFIG_PATH", "#{Formula["openssl"].opt_prefix}/lib/pkgconfig"
-      args << "--with-ssl=#{Formula["openssl"].opt_prefix}"
-      args << "--with-ca-bundle=#{etc}/openssl/cert.pem"
-    elsif build.with? "libressl"
+    if build.with? "libressl"
       ENV.prepend_path "PKG_CONFIG_PATH", "#{Formula["libressl"].opt_prefix}/lib/pkgconfig"
       args << "--with-ssl=#{Formula["libressl"].opt_prefix}"
       args << "--with-ca-bundle=#{etc}/libressl/cert.pem"
+    elsif MacOS.version < :mountain_lion || build.with?("openssl") || build.with?("nghttp2")
+      ENV.prepend_path "PKG_CONFIG_PATH", "#{Formula["openssl"].opt_prefix}/lib/pkgconfig"
+      args << "--with-ssl=#{Formula["openssl"].opt_prefix}"
+      args << "--with-ca-bundle=#{etc}/openssl/cert.pem"
     else
       args << "--with-darwinssl"
     end