From 3f2a45ecd01187d72152247c44fffc1752d56c03 Mon Sep 17 00:00:00 2001
From: Sander Kranz <sander.kranz@gmail.com>
Date: Fri, 23 Aug 2019 16:59:56 +0300
Subject: [PATCH 1/3] Add support of multiple values in the "X-Forwarded-Host"
 header

---
 index.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 4fc55f0..267a7bc 100644
--- a/index.js
+++ b/index.js
@@ -253,7 +253,12 @@ prerender.buildApiUrl = function(req) {
   if (this.protocol) {
     protocol = this.protocol;
   }
-  var fullUrl = protocol + "://" + (this.host || req.headers['x-forwarded-host'] || req.headers['host']) + req.url;
+
+  var hostRaw = this.host || req.headers['x-forwarded-host'] || req.headers['host'];
+  // Take the first hostname in case of multiple values
+  var host = ('' + hostRaw).replace(/,.*$/, '');
+  var fullUrl = protocol + "://" + host + req.url;
+
   return prerenderUrl + forwardSlash + fullUrl;
 };
 

From b2b27f7d090076aa9854d40c42f0c37f2d161631 Mon Sep 17 00:00:00 2001
From: Sander Kranz <sander.kranz@gmail.com>
Date: Sat, 24 Aug 2019 05:17:04 +0300
Subject: [PATCH 2/3] Reduce the effect of the previous commit
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Take the first hostname from the “X-Forwarded-Host” header only
---
 index.js | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/index.js b/index.js
index 267a7bc..e2ed51c 100644
--- a/index.js
+++ b/index.js
@@ -253,12 +253,18 @@ prerender.buildApiUrl = function(req) {
   if (this.protocol) {
     protocol = this.protocol;
   }
+  
+  var host = '';
+  if (this.host) {
+    host = this.host;
+  } else if (req.headers['x-forwarded-host']) {
+    // Take the first hostname in case of multiple values
+    host = req.headers['x-forwarded-host'].replace(/,.*$/, '');
+  } else if (req.headers['host']) {
+    host = req.headers['host'];
+  }
 
-  var hostRaw = this.host || req.headers['x-forwarded-host'] || req.headers['host'];
-  // Take the first hostname in case of multiple values
-  var host = ('' + hostRaw).replace(/,.*$/, '');
   var fullUrl = protocol + "://" + host + req.url;
-
   return prerenderUrl + forwardSlash + fullUrl;
 };
 

From f8efc7b1b909cfe7d67e8905f52a5a853b76e291 Mon Sep 17 00:00:00 2001
From: Sander Kranz <sander.kranz@gmail.com>
Date: Sat, 24 Aug 2019 05:24:47 +0300
Subject: [PATCH 3/3] Make host variable undefined by default

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index e2ed51c..64bd950 100644
--- a/index.js
+++ b/index.js
@@ -254,7 +254,7 @@ prerender.buildApiUrl = function(req) {
     protocol = this.protocol;
   }
   
-  var host = '';
+  var host;
   if (this.host) {
     host = this.host;
   } else if (req.headers['x-forwarded-host']) {