From 4a12047c61570ec3a4dbf9513b0881b41b224399 Mon Sep 17 00:00:00 2001
From: Guy Benoish <guy.benoish@redislabs.com>
Date: Wed, 13 Nov 2019 16:43:07 +0530
Subject: [PATCH] XADD with ID 0-0 stores an empty key

Calling XADD with 0-0 or 0 would result in creating an
empty key and storing it in the database.
Even worse, because XADD will reply with error the action
will not be replicated, creating a master-replica
inconsistency
---
 src/t_stream.c             | 8 ++++++++
 tests/unit/type/stream.tcl | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/src/t_stream.c b/src/t_stream.c
index 58b59f521..9bf87831f 100644
--- a/src/t_stream.c
+++ b/src/t_stream.c
@@ -1220,6 +1220,14 @@ void xaddCommand(client *c) {
         return;
     }
 
+    /* Return ASAP if minimal ID  (0-0) was given so we avoid possibly creating
+     * a new stream and have streamAppendItem fail, leaving an empty key in the
+     * database. */
+    if (id_given && id.ms == 0 && id.seq == 0) {
+        addReplyError(c,"The ID specified in XADD must be greater than 0-0");
+        return;
+    }
+
     /* Lookup the stream at key. */
     robj *o;
     stream *s;
diff --git a/tests/unit/type/stream.tcl b/tests/unit/type/stream.tcl
index aa9c5f3a9..a4431c654 100644
--- a/tests/unit/type/stream.tcl
+++ b/tests/unit/type/stream.tcl
@@ -123,6 +123,12 @@ start_server {
         assert {[r xlen mystream] == $j}
     }
 
+    test {XADD with ID 0-0} {
+        r DEL mystream
+        catch {r XADD mystream 0-0 k v} err
+        assert {[r EXISTS mystream] == 0}
+    }
+
     test {XRANGE COUNT works as expected} {
         assert {[llength [r xrange mystream - + COUNT 10]] == 10}
     }