Ensure that custom endpoints have a defined scheme and host

src/ClientResolver.php

@@ -57,6 +57,7 @@ class ClientResolver
             'type'  => 'value',
             'valid' => ['string'],
             'doc'   => 'The full URI of the webservice. This is only required when connecting to a custom endpoint (e.g., a local version of S3).',
+            'fn'    => [__CLASS__, '_apply_endpoint'],
         ],
         'region' => [
             'type'     => 'value',
@@ -301,7 +302,7 @@ private function invalidType($name, $provided)
             . "provided for \"{$name}\". Expected {$expected}, but got "
             . describe_type($provided) . "\n\n"
             . $this->getArgMessage($name);
-        throw new \InvalidArgumentException($msg);
+        throw new IAE($msg);
     }
 
     /**
@@ -476,6 +477,18 @@ public static function _apply_user_agent($value, array &$args, HandlerList $list
         });
     }
 
+    public static function _apply_endpoint($value, array &$args, HandlerList $list)
+    {
+        $parts = parse_url($value);
+        if (empty($parts['scheme']) || empty($parts['host'])) {
+            throw new IAE(
+                'Endpoints must be full URIs and include a scheme and host'
+            );
+        }
+
+        $args['endpoint'] = $value;
+    }
+
     public static function _default_endpoint_provider()
     {
         return EndpointProvider::defaultProvider();

tests/ClientResolverTest.php

@@ -426,4 +426,26 @@ public function testUserAgentAlwaysStartsWithSdkAgentString()
         ClientResolver::_apply_user_agent([], $args, $list);
         call_user_func($list->resolve(), $command, $request);
     }
+
+    public function malformedEndpointProvider()
+    {
+        return [
+            ['www.amazon.com'], // missing protocol
+            ['https://'], // missing host
+        ];
+    }
+
+    /**
+     * @dataProvider malformedEndpointProvider
+     * @param $endpoint
+     *
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage Endpoints must be full URIs and include a scheme and host
+     */
+    public function testRejectsMalformedEndpoints($endpoint)
+    {
+        $list = new HandlerList();
+        $args = [];
+        ClientResolver::_apply_endpoint($endpoint, $args, $list);
+    }
 }