From 99739618d7e1aa0f282099b6a0eb44787d8dbd92 Mon Sep 17 00:00:00 2001
From: Olivier Bellone <ob@stripe.com>
Date: Mon, 8 Oct 2018 17:18:22 +0200
Subject: [PATCH] Store HTTP response headers in case-insensitive array

---
 init.php                                   |  1 +
 lib/HttpClient/CurlClient.php              |  2 +-
 lib/Util/CaseInsensitiveArray.php          | 62 ++++++++++++++++++++++
 tests/Stripe/HttpClient/CurlClientTest.php |  9 ++++
 4 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 lib/Util/CaseInsensitiveArray.php

diff --git a/init.php b/init.php
index c78718008..582b6392d 100644
--- a/init.php
+++ b/init.php
@@ -5,6 +5,7 @@
 
 // Utilities
 require(dirname(__FILE__) . '/lib/Util/AutoPagingIterator.php');
+require(dirname(__FILE__) . '/lib/Util/CaseInsensitiveArray.php');
 require(dirname(__FILE__) . '/lib/Util/LoggerInterface.php');
 require(dirname(__FILE__) . '/lib/Util/DefaultLogger.php');
 require(dirname(__FILE__) . '/lib/Util/RandomGenerator.php');
diff --git a/lib/HttpClient/CurlClient.php b/lib/HttpClient/CurlClient.php
index b25c1c14f..51eec3e18 100644
--- a/lib/HttpClient/CurlClient.php
+++ b/lib/HttpClient/CurlClient.php
@@ -162,7 +162,7 @@ public function request($method, $absUrl, $headers, $params, $hasFile)
         }
 
         // Create a callback to capture HTTP headers for the response
-        $rheaders = [];
+        $rheaders = new Util\CaseInsensitiveArray();
         $headerCallback = function ($curl, $header_line) use (&$rheaders) {
             // Ignore the HTTP request line (HTTP/1.1 200 OK)
             if (strpos($header_line, ":") === false) {
diff --git a/lib/Util/CaseInsensitiveArray.php b/lib/Util/CaseInsensitiveArray.php
new file mode 100644
index 000000000..02c6f26da
--- /dev/null
+++ b/lib/Util/CaseInsensitiveArray.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Stripe\Util;
+
+use ArrayAccess;
+
+/**
+ * CaseInsensitiveArray is an array-like class that ignores case for keys.
+ *
+ * It is used to store HTTP headers. Per RFC 2616, section 4.2:
+ * Each header field consists of a name followed by a colon (":") and the field value. Field names
+ * are case-insensitive.
+ *
+ * In the context of stripe-php, this is useful because the API will return headers with different
+ * case depending on whether HTTP/2 is used or not (with HTTP/2, headers are always in lowercase).
+ */
+class CaseInsensitiveArray implements ArrayAccess
+{
+    private $container = array();
+
+    public function __construct($initial_array = array())
+    {
+        $this->container = array_map("strtolower", $initial_array);
+    }
+
+    public function offsetSet($offset, $value)
+    {
+        $offset = static::maybeLowercase($offset);
+        if (is_null($offset)) {
+            $this->container[] = $value;
+        } else {
+            $this->container[$offset] = $value;
+        }
+    }
+
+    public function offsetExists($offset)
+    {
+        $offset = static::maybeLowercase($offset);
+        return isset($this->container[$offset]);
+    }
+
+    public function offsetUnset($offset)
+    {
+        $offset = static::maybeLowercase($offset);
+        unset($this->container[$offset]);
+    }
+
+    public function offsetGet($offset)
+    {
+        $offset = static::maybeLowercase($offset);
+        return isset($this->container[$offset]) ? $this->container[$offset] : null;
+    }
+
+    private static function maybeLowercase($v)
+    {
+        if (is_string($v)) {
+            return strtolower($v);
+        } else {
+            return $v;
+        }
+    }
+}
diff --git a/tests/Stripe/HttpClient/CurlClientTest.php b/tests/Stripe/HttpClient/CurlClientTest.php
index 086e6d3ee..89cf203f2 100644
--- a/tests/Stripe/HttpClient/CurlClientTest.php
+++ b/tests/Stripe/HttpClient/CurlClientTest.php
@@ -225,4 +225,13 @@ public function testSleepTimeShouldAddSomeRandomness()
         $this->assertEquals($baseValue * 4, $this->sleepTimeMethod->invoke($curlClient, 3));
         $this->assertEquals($baseValue * 8, $this->sleepTimeMethod->invoke($curlClient, 4));
     }
+
+    public function testResponseHeadersCaseInsensitive()
+    {
+        $charge = Charge::all();
+
+        $headers = $charge->getLastResponse()->headers;
+        $this->assertNotNull($headers['request-id']);
+        $this->assertEquals($headers['request-id'], $headers['Request-Id']);
+    }
 }