Add support for custom curl options.

Add ability for users to send arbitrary curl options. The provided curl
options will overwrite any options set by the adapter.

src/Http/Client/Adapter/Curl.php

@@ -19,8 +19,12 @@
 use Cake\Http\Exception\HttpException;
 
 /**
- * Implements sending Cake\Http\Client\Request
- * via ext/curl.
+ * Implements sending Cake\Http\Client\Request via ext/curl.
+ *
+ * In addition to the standard options documented in Cake\Http\Client,
+ * this adapter supports all available curl options. Additional curl options
+ * can be set via the `curl` option key when making requests or configuring
+ * a client.
  */
 class Curl implements AdapterInterface
 {
@@ -96,7 +100,6 @@ public function buildOptions(Request $request, array $options)
             'timeout' => CURLOPT_TIMEOUT,
             'ssl_verify_peer' => CURLOPT_SSL_VERIFYPEER,
             'ssl_verify_host' => CURLOPT_SSL_VERIFYHOST,
-            'ssl_verify_status' => CURLOPT_SSL_VERIFYSTATUS,
             'ssl_cafile' => CURLOPT_CAINFO,
             'ssl_local_cert' => CURLOPT_SSLCERT,
             'ssl_passphrase' => CURLOPT_SSLCERTPASSWD,
@@ -109,6 +112,12 @@ public function buildOptions(Request $request, array $options)
         if (isset($options['proxy']['proxy'])) {
             $out[CURLOPT_PROXY] = $options['proxy']['proxy'];
         }
+        if (isset($options['curl']) && is_array($options['curl'])) {
+            // Can't use array_merge() because keys will be re-ordered.
+            foreach ($options['curl'] as $key => $value) {
+                $out[$key] = $value;
+            }
+        }
 
         return $out;
     }

tests/TestCase/Http/Client/Adapter/CurlTest.php

@@ -272,4 +272,34 @@ public function testBuildOptionsProxy()
         ];
         $this->assertSame($expected, $result);
     }
+
+    /**
+     * Test converting client options into curl ones.
+     *
+     * @return void
+     */
+    public function testBuildOptionsCurlOptions()
+    {
+        $options = [
+            'curl' => [
+                CURLOPT_USERAGENT => 'Super-secret'
+            ]
+        ];
+        $request = new Request('http://localhost/things', 'GET');
+        $result = $this->curl->buildOptions($request, $options);
+        $expected = [
+            CURLOPT_URL => 'http://localhost/things',
+            CURLOPT_HTTP_VERSION => '1.1',
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_HEADER => true,
+            CURLOPT_HTTPHEADER => [
+                'Connection: close',
+                'User-Agent: CakePHP',
+            ],
+            CURLOPT_HTTPGET => true,
+            CURLOPT_CAINFO => $this->caFile,
+            CURLOPT_USERAGENT => 'Super-secret'
+        ];
+        $this->assertSame($expected, $result);
+    }
 }