Derive RDAP link paths from the received query

The former method -- a config string -- was cumbersome, as each Nomulus system would have to configure the link base to its own URL.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=173567021

java/google/registry/request/FullServletPath.java

@@ -0,0 +1,30 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.request;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import javax.inject.Qualifier;
+
+/**
+ * Dagger qualifier for the HTTP servlet path, prepended with scheme, host and port.
+ *
+ * See {@link javax.servlet.http.HttpServletRequest#getServletPath}
+ */
+@Qualifier
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+public @interface FullServletPath {}

java/google/registry/request/RequestModule.java

@@ -90,6 +90,20 @@ public final class RequestModule {
     return req.getRequestURI();
   }
 
+  @Provides
+  @FullServletPath
+  static String provideFullServletPath(HttpServletRequest req) {
+    // Include the port only if it differs from the default for the scheme.
+    if ((req.getScheme().equals("http") && (req.getServerPort() == 80))
+        || (req.getScheme().equals("https") && (req.getServerPort() == 443))) {
+      return String.format("%s://%s%s", req.getScheme(), req.getServerName(), req.getServletPath());
+    } else {
+      return String.format(
+          "%s://%s:%d%s",
+          req.getScheme(), req.getServerName(), req.getServerPort(), req.getServletPath());
+    }
+  }
+
   @Provides
   @RequestMethod
   static Action.Method provideRequestMethod(HttpServletRequest req) {