Add option to recompile Node library without ALPN support

binding.gyp

@@ -43,7 +43,11 @@
     # out. It can be re-enabled for one build by setting the npm config
     # variable grpc_uv to true, and it can be re-enabled permanently by
     # setting it to true here.
-    'grpc_uv%': 'false'
+    'grpc_uv%': 'false',
+    # Some Node installations use the system installation of OpenSSL, and on
+    # some systems, the system OpenSSL still does not have ALPN support. This
+    # will let users recompile gRPC to work without ALPN.
+    'grpc_alpn%': 'true'
   },
   'target_defaults': {
     'include_dirs': [
@@ -56,8 +60,6 @@
     'conditions': [
       ['runtime=="node" and grpc_uv=="true"', {
         'defines': [
-          # Disabling this while bugs are ironed out. Uncomment this to
-          # re-enable libuv integration in C core.
           'GRPC_UV'
         ]
       }],
@@ -75,10 +77,16 @@
           'OPENSSL_NO_ASM'
         ]
       }, {
-        # As of the beginning of 2017, we only support versions of Node with
-        # embedded versions of OpenSSL that support ALPN
-        'defines': [
-          'TSI_OPENSSL_ALPN_SUPPORT=1'
+        'conditions': [
+          ['grpc_alpn=="true"', {
+            'defines': [
+              'TSI_OPENSSL_ALPN_SUPPORT=1'
+            ],
+          }, {
+            'defines': [
+              'TSI_OPENSSL_ALPN_SUPPORT=0'
+            ],
+          }]
         ],
         'include_dirs': [
           '<(node_root_dir)/deps/openssl/openssl/include',

templates/binding.gyp.template

@@ -45,7 +45,11 @@
       # out. It can be re-enabled for one build by setting the npm config
       # variable grpc_uv to true, and it can be re-enabled permanently by
       # setting it to true here.
-      'grpc_uv%': 'false'
+      'grpc_uv%': 'false',
+      # Some Node installations use the system installation of OpenSSL, and on
+      # some systems, the system OpenSSL still does not have ALPN support. This
+      # will let users recompile gRPC to work without ALPN.
+      'grpc_alpn%': 'true'
     },
     'target_defaults': {
       'include_dirs': [
@@ -58,8 +62,6 @@
       'conditions': [
         ['runtime=="node" and grpc_uv=="true"', {
           'defines': [
-            # Disabling this while bugs are ironed out. Uncomment this to
-            # re-enable libuv integration in C core.
             'GRPC_UV'
           ]
         }],
@@ -77,10 +79,16 @@
             'OPENSSL_NO_ASM'
           ]
         }, {
-          # As of the beginning of 2017, we only support versions of Node with
-          # embedded versions of OpenSSL that support ALPN
-          'defines': [
-            'TSI_OPENSSL_ALPN_SUPPORT=1'
+          'conditions': [
+            ['grpc_alpn=="true"', {
+              'defines': [
+                'TSI_OPENSSL_ALPN_SUPPORT=1'
+              ],
+            }, {
+              'defines': [
+                'TSI_OPENSSL_ALPN_SUPPORT=0'
+              ],
+            }]
           ],
           'include_dirs': [
             '<(node_root_dir)/deps/openssl/openssl/include',