Support appending header ranges to CorsSettings.

Provide a CorsSettings builder method to allow additional header ranges to be added, and the underlying ability to concatenate HttpHeaderRange instances to support it.
This supports scenarios where complex CorsSettings defaults are provided by downstream libraries (e.g. pekko-grpc) but still need to be extended/adapted by end user applications.

Author: timw

http-cors/src/main/java/org/apache/pekko/http/cors/javadsl/model/HttpHeaderRange.java

@@ -24,6 +24,8 @@
 public abstract class HttpHeaderRange {
   public abstract boolean matches(String header);
 
+  public abstract HttpHeaderRange concat(HttpHeaderRange range);
+
   public static HttpHeaderRange create(String... headers) {
     return HttpHeaderRange$.MODULE$.apply(Util.convertArray(headers));
   }

http-cors/src/main/mima-filters/2.0.x.backwards.excludes/new-methods.excludes

@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+# New methods added in 2.0.x
+ProblemFilters.exclude[ReversedMissingMethodProblem]("org.apache.pekko.http.cors.javadsl.model.HttpHeaderRange.concat")
+ProblemFilters.exclude[ReversedMissingMethodProblem]("org.apache.pekko.http.cors.scaladsl.model.HttpHeaderRange.concat")

http-cors/src/main/scala/org/apache/pekko/http/cors/CorsJavaMapping.scala

@@ -27,5 +27,8 @@ private[pekko] object CorsJavaMapping {
   object Implicits {
     implicit object CorsSettingsMapping
         extends JavaMapping.Inherited[javadsl.settings.CorsSettings, scaladsl.settings.CorsSettings]
+
+    implicit object HttpHeaderRangeMapping
+        extends JavaMapping.Inherited[javadsl.model.HttpHeaderRange, scaladsl.model.HttpHeaderRange]
   }
 }

http-cors/src/main/scala/org/apache/pekko/http/cors/scaladsl/model/HttpHeaderRange.scala

@@ -20,19 +20,34 @@ package org.apache.pekko.http.cors.scaladsl.model
 import scala.collection.immutable.Seq
 
 import org.apache.pekko
+import pekko.http.cors.CorsJavaMapping.Implicits._
 import pekko.http.cors.javadsl
+import pekko.http.impl.util.JavaMapping
 import pekko.util.Helpers
 
-abstract class HttpHeaderRange extends javadsl.model.HttpHeaderRange
+sealed abstract class HttpHeaderRange extends javadsl.model.HttpHeaderRange {
+  override def concat(range: javadsl.model.HttpHeaderRange): HttpHeaderRange
+
+  def ++(range: javadsl.model.HttpHeaderRange): HttpHeaderRange = concat(range)
+}
 
 object HttpHeaderRange {
   case object `*` extends HttpHeaderRange {
     def matches(header: String) = true
+
+    override def concat(range: javadsl.model.HttpHeaderRange): HttpHeaderRange = this
   }
 
   final case class Default(headers: Seq[String]) extends HttpHeaderRange {
     private val lowercaseHeaders: Seq[String] = headers.map(Helpers.toRootLowerCase)
     def matches(header: String): Boolean = lowercaseHeaders.contains(Helpers.toRootLowerCase(header))
+
+    override def concat(range: javadsl.model.HttpHeaderRange): HttpHeaderRange = {
+      JavaMapping.toScala(range) match {
+        case `*`              => `*`
+        case Default(headers) => Default(this.headers ++ headers)
+      }
+    }
   }
 
   def apply(headers: String*): Default = Default(Seq(headers: _*))

http-cors/src/test/scala/org/apache/pekko/http/cors/scaladsl/model/HttpHeaderRangeSpec.scala

@@ -0,0 +1,107 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.pekko.http.cors.scaladsl.model
+
+import org.apache.pekko.http.scaladsl.model.headers.{ `Content-Type`, Accept }
+import org.scalatest.Inspectors
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+class HttpHeaderRangeSpec extends AnyWordSpec with Matchers with Inspectors {
+
+  "The `*` range" should {
+    "match any Header" in {
+      val headers = Seq(
+        `Content-Type`.name,
+        "conTent-tyPe",
+        Accept.name,
+        "x-any-random-header-name")
+
+      forAll(headers) { o => HttpHeaderRange.*.matches(o) shouldBe true }
+    }
+
+    "be printed as `*`" in {
+      HttpHeaderRange.*.toString shouldBe "*"
+    }
+  }
+
+  "The default range" should {
+    val range = HttpHeaderRange(`Content-Type`.name, Accept.name)
+
+    "match headers ignoring case" in {
+      val headers = Seq(
+        `Content-Type`.name,
+        `Content-Type`.name.toUpperCase(),
+        `Content-Type`.name.toLowerCase(),
+        "conTent-tyPe",
+        Accept.name,
+        Accept.name.toUpperCase(),
+        Accept.name.toLowerCase(),
+        "aCcepT")
+
+      forAll(headers) { o => range.matches(o) shouldBe true }
+    }
+
+    "not match other headers" in {
+      val headers = Seq(
+        "Content-Type2",
+        "Content-Typ",
+        "x-any-random-header-name")
+
+      forAll(headers) { o => range.matches(o) shouldBe false }
+    }
+  }
+
+  "Concatenation of ranges" should {
+    "match both ranges" in {
+      val range1 = HttpHeaderRange(`Content-Type`.name)
+      val range2 = HttpHeaderRange(Accept.name)
+
+      val combined = range1 ++ range2
+
+      val headers = Seq(
+        `Content-Type`.name,
+        Accept.name)
+      val notHeaders = Seq(
+        "Content-Type2",
+        "Content-Typ",
+        "x-any-random-header-name")
+
+      forAll(headers) { o => combined.matches(o) shouldBe true }
+      forAll(notHeaders) { o => combined.matches(o) shouldBe false }
+    }
+
+    "combine with the `*` range" in {
+      val range1 = HttpHeaderRange(`Content-Type`.name)
+      val starRange = HttpHeaderRange.*
+
+      val combinedBefore = starRange ++ range1
+      val combinedAfter = range1 ++ starRange
+
+      val headers = Seq(
+        `Content-Type`.name,
+        "conTent-tyPe",
+        Accept.name,
+        "x-any-random-header-name")
+
+      forAll(headers) { o => combinedBefore.matches(o) shouldBe true }
+      forAll(headers) { o => combinedAfter.matches(o) shouldBe true }
+    }
+  }
+
+}