Allow sharing private files through pre-signed URLs

Signed-off-by: Knut Ahlers <knut@ahlers.me>

app.js

@@ -138,6 +138,28 @@ function getMimeType(filename) {
   return mime
 }
 
+// getPublicURL returns the public URL of the file. If the file is private and
+// the signed parameter is set to true a presigned URL will be created
+function getPublicURL(signed = false) {
+  let pub = $('#acl').data('public')
+  let filename = $('#filename').val()
+
+  if (pub) {
+    return window.past3_config.base_url + getFilePrefix() + filename
+  }
+
+  if (signed) {
+    let s3 = new AWS.S3()
+    return s3.getSignedUrl('getObject', {
+      Bucket: window.past3_config.bucket,
+      Expires: window.past3_config.private_share_expiry,
+      Key: getFilePrefix() + filename,
+    })
+  }
+
+  return 'File is private, no URL available'
+}
+
 // info displays the info in the frontend
 function info(msg) {
   showAlert('info', msg, 10000)
@@ -250,6 +272,12 @@ function init() {
       return false
     }
   })
+
+  new ClipboardJS('#copyURL', {
+    text: () => {
+      return getPublicURL(true)
+    }
+  })
 }
 
 // listFiles triggers a reload of the file list
@@ -401,11 +429,11 @@ function updateFileURL() {
 
   setEditorMime(filename)
 
+  $('#file-url').val(getPublicURL(false))
+
   if (pub) {
-    $('#file-url').val(window.past3_config.base_url + getFilePrefix() + filename)
     $('#acl').find('i').removeClass('fa-unlock').addClass('fa-lock')
   } else {
-    $('#file-url').val('File is private, no URL available')
     $('#acl').find('i').removeClass('fa-lock').addClass('fa-unlock')
   }
 }

config.yml

@@ -25,3 +25,7 @@ identity_pool_id: 'eu-west-1:8605f42e-f1e2-4c71-a796-a96ed9e79930'
 
 # AWS region of the bucket
 region: eu-west-1
+
+# Expiry in seconds set on pre-signed URLs for private files
+# Minimum is 1s, maximum 604800s (seven days)
+private_share_expiry: 900

index.html

@@ -92,7 +92,8 @@
                   </div>
                   <input type="text" class="form-control" id="file-url" placeholder="n/a" readonly>
                   <div class="input-group-append">
-                    <button type="button" class="btn btn-secondary" id="acl" title="Change ACL (Ctrl + L)"><i class="fas fa-fw fa-lock"></i></button>
+                    <button type="button" class="btn btn-outline-info" id="acl" title="Change ACL (Ctrl + L)"><i class="fas fa-fw fa-lock"></i></button>
+                    <button type="button" class="btn btn-primary" id="copyURL" title="Copy share URL"><i class="fas fa-fw fa-clipboard"></i></button>
                   </div>
                 </div>
                 
@@ -167,6 +168,9 @@
     <script src="https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.40.2/mode/meta.min.js"
             integrity="sha256-+YoTLm1iuD8g9GwmNrGt+xLBvrfbd2B+6C38qtkNE28=" crossorigin="anonymous"></script>
 
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.1/clipboard.min.js"
+            integrity="sha256-hIvIxeqhGZF+VVeM55k0mJvWpQ6gTkWk3Emc+NmowYA=" crossorigin="anonymous"></script>
+
     <script src="app.js"></script>
     <script src="https://apis.google.com/js/platform.js?onload=renderButton" async defer></script>
   </body>