feat(app-server): add cache-control & etag of http request for gridfs…

… files;
labring · Aug 16, 2021 · acc3c44 · acc3c44
1 parent acc2e8e
commit acc3c44
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Showing 4 changed files with 46 additions and 5 deletions.
diff --git a/packages/app-server/src/config.ts b/packages/app-server/src/config.ts
@@ -54,6 +54,13 @@ export default class Config {
     return process.env['FILE_SYSTEM_DRIVER'] ?? 'gridfs'
   }
 
+  /**
+   * value of HTTP header Cache-Control: max-age=120 while download file
+   */
+  static get FILE_SYSTEM_HTTP_CACHE_CONTROL(): string {
+    return process.env['FILE_SYSTEM_HTTP_CACHE_CONTROL']
+  }
+
   /**
    * the `temp path`
    */

diff --git a/packages/app-server/src/index.ts b/packages/app-server/src/index.ts
@@ -17,6 +17,7 @@ server.all('*', function (_req, res, next) {
   res.header('Access-Control-Allow-Origin', '*')
   res.header('Access-Control-Allow-Headers', 'Authorization, Content-Type')
   res.header('Access-Control-Allow-Methods', '*')
+  res.header('X-Powered-By', 'LaF Server')
   next()
 })
 

diff --git a/packages/app-server/src/router/file/gridfs.ts b/packages/app-server/src/router/file/gridfs.ts
@@ -3,7 +3,8 @@ import * as fs from 'fs'
 import * as express from 'express'
 import { GridFSBucket } from 'mongodb'
 import { Globals } from '../../lib/globals'
-import { checkFileOperationToken, FS_OPERATION } from './utils'
+import { checkFileOperationToken, FS_OPERATION, generateETag } from './utils'
+import Config from '../../config'
 
 
 export const GridFSHandlers = {
@@ -37,7 +38,14 @@ async function handleUploadFile(req: express.Request, res: express.Response) {
   const bucket = new GridFSBucket(Globals.accessor.db, { bucketName: bucket_name })
 
   const stream = bucket.openUploadStream(file.filename, {
-    metadata: { original_name: file.originalname, created_by: auth?.uid, bucket: bucket_name, created_at: Date.now() },
+    metadata: {
+      original_name: file.originalname,
+      created_by: auth?.uid,
+      bucket: bucket_name,
+      created_at: Date.now(),
+      contentType: file.mimetype
+    },
+    // @deprecated: this field will be deprecated in future, use metadata instead. keep it now for history reasons
     contentType: file.mimetype
   })
 
@@ -91,8 +99,22 @@ async function handleDownloadFile(req: express.Request, res: express.Response) {
       return res.status(404).send('Not Found')
     }
 
-    if (file?.contentType) {
-      res.contentType(file.contentType)
+    const contentType = file?.metadata?.contentType || file?.contentType
+    if (contentType) {
+      res.contentType(contentType)
+    }
+
+    if (Config.FILE_SYSTEM_HTTP_CACHE_CONTROL) {
+      res.set('Cache-Control', Config.FILE_SYSTEM_HTTP_CACHE_CONTROL)
+    }
+    res.set('Last-Modified', file.uploadDate.toUTCString())
+
+    // process cache policy with ETag & If-None-Match
+    const ETag = generateETag(file.length, file.uploadDate.toString(), file.filename)
+    res.set('ETag', ETag)
+    if (req.header('If-None-Match') === ETag) {
+      res.status(304).send('Not Modified')
+      return
     }
 
     res.set('x-bucket', bucket_name)

diff --git a/packages/app-server/src/router/file/utils.ts b/packages/app-server/src/router/file/utils.ts
@@ -1,6 +1,6 @@
 import assert = require("assert")
 import { parseToken } from "../../lib/utils/token"
-
+import * as crypto from 'crypto'
 
 /**
  * file operations
@@ -65,4 +65,15 @@ export function checkFileOperationToken(bucket: string, token: string, operation
   }
 
   return [0, null]
+}
+
+
+/**
+ * generate http ETag of a file
+ * @param file_size the size of file in bytes
+ * @param update_date the update date time of file
+ * @param filename file name
+ */
+export function generateETag(file_size: number, update_date: string, filename: string) {
+  return crypto.createHash('md5').update(`${filename}#${file_size}#${update_date}`).digest('hex')
 }