Minimize number of errors in LZString parsing errors for history

Right now we still see a lot of LZString parsing errors in the logs. 
They probably come from the user history. We should minimize the number 
by add the basic length check there as well.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/history.js b/lib/history.js
index c7d2472c..63be4521 100644
--- a/lib/history.js
+++ b/lib/history.js
@@ -31,6 +31,15 @@ function getHistory (userid, callback) {
       history = JSON.parse(user.history)
       // migrate LZString encoded note id to base64url encoded note id
       for (let i = 0, l = history.length; i < l; i++) {
+        // Calculate minimal string length for an UUID that is encoded
+        // base64 encoded and optimize comparsion by using -1
+        // this should make a lot of LZ-String parsing errors obsolete
+        // as we can assume that a nodeId that is 48 chars or longer is a
+        // noteID.
+        const base64UuidLength = ((4 * 36) / 3) - 1
+        if (!(history[i].id.length > base64UuidLength)) {
+          continue
+        }
         try {
           let id = LZString.decompressFromBase64(history[i].id)
           if (id && models.Note.checkNoteIdValid(id)) {