[couchdb] 01/01: Prevent users from modifying the reserved _replication_* fields

[rn...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

rnewson pushed a commit to branch replicator_vdu_special_fields
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit a7e09de233d9ceb27a97fb848aecdd2c5c160da3
Author: Robert Newson <rn...@apache.org>
AuthorDate: Mon Feb 28 19:04:28 2022 +0000

    Prevent users from modifying the reserved _replication_* fields
    
    Only the replicator is permitted to do this. This PR enhances the
    existing VDU to prohibit users from modifying the fields, in case the
    user mistakenly believes that such edits are understood as
    instructions to the replicator.
---
 .../src/couch_replicator_js_functions.hrl            | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/couch_replicator/src/couch_replicator_js_functions.hrl b/src/couch_replicator/src/couch_replicator_js_functions.hrl
index d410433..92839d8 100644
--- a/src/couch_replicator/src/couch_replicator_js_functions.hrl
+++ b/src/couch_replicator/src/couch_replicator_js_functions.hrl
@@ -58,6 +58,26 @@
             return;
         }
 
+        // Only the replicator may change these fields, though any authorised
+        // user may delete them.
+        if (oldDoc) {
+            var protectedFields = [
+                '_replication_state',
+                '_replication_state_time',
+                '_replication_state_reason',
+                '_replication_id',
+                '_replication_stats'
+            ]
+            for (var i = 0; i < protectedFields.length; i++) {
+                var protectedField = protectedFields[i];
+                if (typeof(oldDoc[protectedField]) === 'string' &&
+                    typeof(newDoc[protectedField]) === 'string' &&
+                    oldDoc[protectedField] != newDoc[protectedField]) {
+                    reportError('Only the replicator may modify the ' + protectedField + ' field.');
+                }
+            }
+        }
+
         if (newDoc._replication_state === 'failed') {
             // Skip validation in case when we update the document with the
             // failed state. In this case it might be malformed. However,