chore: makes lookup for Map getter to be case insensitive (#137). (#139)

openzipkin · Apr 24, 2020 · 7df3e2b · 7df3e2b
1 parent 3a3ae88
commit 7df3e2b
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Showing 2 changed files with 32 additions and 1 deletion.
diff --git a/src/Zipkin/Propagation/Map.php b/src/Zipkin/Propagation/Map.php
@@ -10,6 +10,13 @@ final class Map implements Getter, Setter
 {
     /**
      * {@inheritdoc}
+     *
+     * If the carrier is an array, the lookup is case insensitive, this is
+     * mainly because Map getter is commonly used for those cases where the
+     * HTTP framework does not follow the PSR request/response objects (e.g.
+     * Symfony) and thus the header bag should be treated as a map. ArrayAccess
+     * can't be case insensitive because we can not know the keys on beforehand.
+     *
      * @param array|ArrayAccess $carrier
      */
     public function get($carrier, $key)
@@ -21,7 +28,12 @@ public function get($carrier, $key)
         }
 
         if (is_array($carrier)) {
-            return array_key_exists($lKey, $carrier) ? $carrier[$lKey] : null;
+            if (empty($carrier)) {
+                return null;
+            }
+
+            $lcCarrier = array_change_key_case($carrier, CASE_LOWER);
+            return array_key_exists($lKey, $lcCarrier) ? $lcCarrier[$lKey] : null;
         }
 
         throw InvalidPropagationCarrier::forCarrier($carrier);
@@ -41,6 +53,8 @@ public function put(&$carrier, $key, $value)
             throw InvalidPropagationKey::forEmptyKey();
         }
 
+        // Lowercasing the key was a first attempt to be compatible with the
+        // getter when using the Map getter for HTTP headers.
         $lKey = strtolower($key);
 
         if ($carrier instanceof ArrayAccess || is_array($carrier)) {

diff --git a/tests/Unit/Propagation/MapTest.php b/tests/Unit/Propagation/MapTest.php
@@ -12,6 +12,7 @@
 final class MapTest extends PHPUnit_Framework_TestCase
 {
     const TEST_KEY = 'test_key';
+    const TEST_KEY_INSENSITIVE = 'tEsT_KEy';
     const TEST_VALUE = 'test_value';
     const TEST_INVALID_KEY = 1;
     const TEST_EMPTY_KEY = '';
@@ -32,6 +33,22 @@ public function testGetFromMapSuccessForArrayAccessCarrier()
         $this->assertEquals(self::TEST_VALUE, $value);
     }
 
+    public function testGetFromMapCaseInsensitiveSuccess()
+    {
+        $carrier = [self::TEST_KEY_INSENSITIVE => self::TEST_VALUE];
+        $map = new Map();
+        $value = $map->get($carrier, self::TEST_KEY);
+        $this->assertEquals(self::TEST_VALUE, $value);
+    }
+
+    public function testGetFromMapCaseInsensitiveReturnsNull()
+    {
+        $carrier = new ArrayObject([self::TEST_KEY_INSENSITIVE => self::TEST_VALUE]);
+        $map = new Map();
+        $value = $map->get($carrier, self::TEST_KEY);
+        $this->assertNull($value);
+    }
+
     public function testPutToMapFailsDueToInvalidKey()
     {
         $carrier = new ArrayObject();