From 7357332a28a5b496be34f11809227b73ab05e615 Mon Sep 17 00:00:00 2001
From: Chase Coalwell <chasecoa@amazon.com>
Date: Thu, 13 Jun 2019 08:54:18 -0700
Subject: [PATCH] fix json parse error on empty headers (#1819)

---
 .../changelog_fix_json_parse_header.json      |  7 +++++
 src/Api/Parser/AbstractRestParser.php         | 17 +++++++++--
 .../protocols/output/rest-json.json           | 30 +++++++++++++++++++
 3 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100644 .changes/nextrelease/changelog_fix_json_parse_header.json

diff --git a/.changes/nextrelease/changelog_fix_json_parse_header.json b/.changes/nextrelease/changelog_fix_json_parse_header.json
new file mode 100644
index 0000000000..65a55fbb2b
--- /dev/null
+++ b/.changes/nextrelease/changelog_fix_json_parse_header.json
@@ -0,0 +1,7 @@
+[
+    {
+      "type": "enhancement",
+      "category": "Api",
+      "description": "Fix json parse error when extracting header"
+    }
+  ] 
\ No newline at end of file
diff --git a/src/Api/Parser/AbstractRestParser.php b/src/Api/Parser/AbstractRestParser.php
index 1e7fa94b1f..c264767f16 100644
--- a/src/Api/Parser/AbstractRestParser.php
+++ b/src/Api/Parser/AbstractRestParser.php
@@ -128,10 +128,21 @@ private function extractHeader(
                     return;
                 }
             case 'string':
-                if ($shape['jsonvalue']) {
-                    $value = $this->parseJson(base64_decode($value), $response);
+                try {
+                    if ($shape['jsonvalue']) {
+                        $value = $this->parseJson(base64_decode($value), $response);
+                    }
+
+                    // If value is not set, do not add to output structure.
+                    if (!isset($value)) {
+                        return;
+                    }
+                    break;
+                } catch (\Exception $e) {
+                    //If the value cannot be parsed, then do not add it to the
+                    //output structure.
+                    return;
                 }
-                break;
         }
 
         $result[$name] = $value;
diff --git a/tests/Api/test_cases/protocols/output/rest-json.json b/tests/Api/test_cases/protocols/output/rest-json.json
index 60095401ec..180328f16e 100644
--- a/tests/Api/test_cases/protocols/output/rest-json.json
+++ b/tests/Api/test_cases/protocols/output/rest-json.json
@@ -702,6 +702,36 @@
           "headers": {"X-Amz-Foo": "eyJGb28iOiJCYXIifQ=="},
           "body": ""
         }
+      },
+      {
+        "given": {
+          "output": {
+            "shape": "OutputShape"
+          },
+          "name": "OperationName"
+        },
+        "result": {
+          "Attr": {}
+        },
+        "response": {
+          "status_code": 200,
+          "headers": {"X-Amz-Foo": "e30="},
+          "body": ""
+        }
+      },
+      {
+        "given": {
+          "output": {
+            "shape": "OutputShape"
+          },
+          "name": "OperationName"
+        },
+        "result": {},
+        "response": {
+          "status_code": 200,
+          "headers": {"X-Amz-Foo": ""},
+          "body": ""
+        }
       }
     ]
   }