From 7061569bf4e8eee99cf6f90ef36308c4fd6fa3bf Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Mon, 4 Oct 2021 16:26:40 +0100
Subject: [PATCH] Don't send retained messages when a shared subscription is
 made.

---
 ChangeLog.txt | 1 +
 src/retain.c  | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index 739d16a1..38098d77 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -7,6 +7,7 @@ Broker:
   true. Closes #2314.
 - Various fixes around inflight quota management. Closes #2306.
 - Fix problem parsing config files with Windows line endings. Closes #2297.
+- Don't send retained messages when a shared subscription is made.
 
 Client library:
 - Initialise sockpairR/W to invalid in `mosquitto_reinitialise()` to avoid
diff --git a/src/retain.c b/src/retain.c
index 6e324afa..e5065daf 100644
--- a/src/retain.c
+++ b/src/retain.c
@@ -265,6 +265,10 @@ int retain__queue(struct mosquitto *context, const char *sub, uint8_t sub_qos, u
 	assert(context);
 	assert(sub);
 
+	if(!strncmp(sub, "$share/", strlen("$share/"))){
+		return MOSQ_ERR_SUCCESS;
+	}
+
 	rc = sub__topic_tokenise(sub, &local_sub, &split_topics, NULL);
 	if(rc) return rc;