From dde68ce753e6fda6e67b42c7e7a4e06c3b8ef732 Mon Sep 17 00:00:00 2001
From: Favour Ohanekwu <fohanekwu@gmail.com>
Date: Sat, 8 Jan 2022 23:15:09 -0800
Subject: [PATCH] prevent corruption of downloaded file when base64 string is
 used in download action  (#10254)

---
 .../sagas/ActionExecution/DownloadActionSaga.ts    | 14 ++++++++++++--
 .../sagas/ActionExecution/downloadActionUtils.ts   | 11 +++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 app/client/src/sagas/ActionExecution/downloadActionUtils.ts

diff --git a/app/client/src/sagas/ActionExecution/DownloadActionSaga.ts b/app/client/src/sagas/ActionExecution/DownloadActionSaga.ts
index a9a87e0f74..7142b9f69e 100644
--- a/app/client/src/sagas/ActionExecution/DownloadActionSaga.ts
+++ b/app/client/src/sagas/ActionExecution/DownloadActionSaga.ts
@@ -1,4 +1,4 @@
-import { getType, isURL, Types } from "utils/TypeHelpers";
+import { getType, Types } from "utils/TypeHelpers";
 import downloadjs from "downloadjs";
 import AppsmithConsole from "utils/AppsmithConsole";
 import Axios from "axios";
@@ -7,6 +7,7 @@ import {
   DownloadActionDescription,
 } from "entities/DataTree/actionTriggers";
 import { ActionValidationError } from "sagas/ActionExecution/errorUtils";
+import { isBase64String, isUrlString } from "./downloadActionUtils";
 
 export default async function downloadSaga(
   action: DownloadActionDescription["payload"],
@@ -27,7 +28,7 @@ export default async function downloadSaga(
     AppsmithConsole.info({
       text: `download('${jsonString}', '${name}', '${type}') was triggered`,
     });
-  } else if (dataType === Types.STRING && isURL(data)) {
+  } else if (isUrlString(data)) {
     // In the event that a url string is supplied, we need to fetch the image with the response type arraybuffer.
     // This also covers the case where the file to be downloaded is Binary.
     Axios.get(data, { responseType: "arraybuffer" }).then((res) => {
@@ -36,6 +37,15 @@ export default async function downloadSaga(
         text: `download('${data}', '${name}', '${type}') was triggered`,
       });
     });
+  } else if (isBase64String(data)) {
+    Axios.get(`data:${type};base64,${data}`, {
+      responseType: "arraybuffer",
+    }).then((res) => {
+      downloadjs(res.data, name, type);
+      AppsmithConsole.info({
+        text: `download('${data}', '${name}', '${type}') was triggered`,
+      });
+    });
   } else {
     downloadjs(data, name, type);
     AppsmithConsole.info({
diff --git a/app/client/src/sagas/ActionExecution/downloadActionUtils.ts b/app/client/src/sagas/ActionExecution/downloadActionUtils.ts
new file mode 100644
index 0000000000..e1cb23e780
--- /dev/null
+++ b/app/client/src/sagas/ActionExecution/downloadActionUtils.ts
@@ -0,0 +1,11 @@
+import { getType, isURL, Types } from "utils/TypeHelpers";
+
+const BASE64_STRING_REGEX = /^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)?$/;
+
+export const isBase64String = (data: any) => {
+  return getType(data) === Types.STRING && BASE64_STRING_REGEX.test(data);
+};
+
+export const isUrlString = (data: any) => {
+  return getType(data) === Types.STRING && isURL(data);
+};