From 55c57c487e4e71bf682281ab839b58d5888a92b8 Mon Sep 17 00:00:00 2001
From: user411 <erickson.ivan@gmail.com>
Date: Fri, 27 Aug 2021 06:57:36 -0600
Subject: [PATCH] Add CORS handling for running from a local dev server (#3612)

---
 .../bitcoins/server/routes/CORSHandler.scala  | 45 +++++++++++++++++++
 .../org/bitcoins/server/routes/Server.scala   |  5 ++-
 2 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 app/server-routes/src/main/scala/org/bitcoins/server/routes/CORSHandler.scala

diff --git a/app/server-routes/src/main/scala/org/bitcoins/server/routes/CORSHandler.scala b/app/server-routes/src/main/scala/org/bitcoins/server/routes/CORSHandler.scala
new file mode 100644
index 0000000000..0cde6f62f1
--- /dev/null
+++ b/app/server-routes/src/main/scala/org/bitcoins/server/routes/CORSHandler.scala
@@ -0,0 +1,45 @@
+package org.bitcoins.server.routes
+
+import akka.http.scaladsl.model.{HttpResponse, StatusCodes}
+import akka.http.scaladsl.model.headers._
+import akka.http.scaladsl.model.HttpMethods._
+import akka.http.scaladsl.server.Directive0
+import akka.http.scaladsl.server.Directives._
+import akka.http.scaladsl.server.Route
+
+/** Add CORS handling for accessing backend over localhost from modern browsers
+  * @see dzone.com/articles/handling-cors-in-akka-http
+  */
+trait CORSHandler {
+
+  private val corsResponseHeaders = List(
+    `Access-Control-Allow-Origin`.*,
+    `Access-Control-Allow-Credentials`(true),
+    `Access-Control-Allow-Headers`("Authorization",
+                                   "Content-Type",
+                                   "X-Requested-With")
+  )
+
+  //this directive adds access control headers to normal responses
+  private def addAccessControlHeaders: Directive0 = {
+    respondWithHeaders(corsResponseHeaders)
+  }
+
+  //this handles preflight OPTIONS requests.
+  private def preflightRequestHandler: Route = options {
+    complete(
+      HttpResponse(StatusCodes.OK).withHeaders(
+        `Access-Control-Allow-Methods`(OPTIONS, POST, PUT, GET, DELETE)))
+  }
+
+  // Wrap the Route with this method to enable adding of CORS headers
+  def corsHandler(r: Route): Route = addAccessControlHeaders {
+    preflightRequestHandler ~ r
+  }
+
+  // Helper method to add CORS headers to HttpResponse
+  // preventing duplication of CORS headers across code
+  def addCORSHeaders(response: HttpResponse): HttpResponse =
+    response.withHeaders(corsResponseHeaders)
+
+}
diff --git a/app/server-routes/src/main/scala/org/bitcoins/server/routes/Server.scala b/app/server-routes/src/main/scala/org/bitcoins/server/routes/Server.scala
index c737014340..1ea8976d89 100644
--- a/app/server-routes/src/main/scala/org/bitcoins/server/routes/Server.scala
+++ b/app/server-routes/src/main/scala/org/bitcoins/server/routes/Server.scala
@@ -18,7 +18,8 @@ case class Server(
     handlers: Seq[ServerRoute],
     rpcbindOpt: Option[String],
     rpcport: Int)(implicit system: ActorSystem)
-    extends HttpLogger {
+    extends HttpLogger
+    with CORSHandler {
 
   import system.dispatcher
 
@@ -54,7 +55,7 @@ case class Server(
 
     handleRejections(rejectionHandler) {
       handleExceptions(exceptionHandler) {
-        route
+        corsHandler(route)
       }
     }
   }