Decline unsubscribe related command in non-subscribed mode

src/server.c

@@ -4037,6 +4037,12 @@ int processCommand(client *c) {
         return C_OK;
     }
 
+    /* Not allow several UNSUBSCRIBE commands executed under non-pubsub mode */
+    if (!c->flag.pubsub && (c->cmd->proc == unsubscribeCommand || c->cmd->proc == sunsubscribeCommand ||
+                            c->cmd->proc == punsubscribeCommand)) {
+        rejectCommandFormat(c, "-NOSUB '%s' command executed not in subscribed mode", c->cmd->fullname);
+        return C_OK;
+    }
     /* Only allow commands with flag "t", such as INFO, REPLICAOF and so on,
      * when replica-serve-stale-data is no and we are a replica with a broken
      * link with primary. */

tests/unit/info.tcl

@@ -426,7 +426,8 @@ start_server {tags {"info" "external:skip"}} {
             set info [r info clients]
             assert_equal [getInfoProperty $info pubsub_clients] {1}
             # non-pubsub clients should not be involved
-            assert_equal {0} [unsubscribe $rd2 {non-exist-chan}]
+            catch {unsubscribe $rd2 {non-exist-chan}} e
+            assert_match {*NOSUB*} $e
             set info [r info clients]
             assert_equal [getInfoProperty $info pubsub_clients] {1}
             # close all clients

tests/unit/pubsub.tcl

@@ -109,10 +109,12 @@ start_server {tags {"pubsub network"}} {
         $rd1 close
     }
 
-    test "UNSUBSCRIBE from non-subscribed channels" {
+    test "UNSUBSCRIBE and PUNSUBSCRIBE from non-subscribed channels" {
         set rd1 [valkey_deferring_client]
-        assert_equal {0 0 0} [unsubscribe $rd1 {foo bar quux}]
-
+        foreach command {unsubscribe punsubscribe} {
+            catch {$command $rd1 {foo bar quux}} e
+            assert_match {*NOSUB*} $e
+        }
         # clean up clients
         $rd1 close
     }
@@ -202,14 +204,6 @@ start_server {tags {"pubsub network"}} {
         $rd close
     } {0} {resp3}
 
-    test "PUNSUBSCRIBE from non-subscribed channels" {
-        set rd1 [valkey_deferring_client]
-        assert_equal {0 0 0} [punsubscribe $rd1 {foo.* bar.* quux.*}]
-
-        # clean up clients
-        $rd1 close
-    }
-
     test "NUMSUB returns numbers, not strings (#1561)" {
         r pubsub numsub abc def
     } {abc 0 def 0}
@@ -247,16 +241,6 @@ start_server {tags {"pubsub network"}} {
         $rd1 close
     }
 
-    test "PUNSUBSCRIBE and UNSUBSCRIBE should always reply" {
-        # Make sure we are not subscribed to any channel at all.
-        r punsubscribe
-        r unsubscribe
-        # Now check if the commands still reply correctly.
-        set reply1 [r punsubscribe]
-        set reply2 [r unsubscribe]
-        concat $reply1 $reply2
-    } {punsubscribe {} 0 unsubscribe {} 0}
-
     ### Keyspace events notification tests
 
     test "Keyspace notifications: we receive keyspace notifications" {

tests/unit/pubsubshard.tcl

@@ -74,9 +74,8 @@ start_server {tags {"pubsubshard external:skip"}} {
 
     test "SUNSUBSCRIBE from non-subscribed channels" {
         set rd1 [valkey_deferring_client]
-        assert_equal {0} [sunsubscribe $rd1 {foo}]
-        assert_equal {0} [sunsubscribe $rd1 {bar}]
-        assert_equal {0} [sunsubscribe $rd1 {quux}]
+        catch {sunsubscribe $rd1 {foo}} e
+        assert_match {*NOSUB*} $e
 
         # clean up clients
         $rd1 close
@@ -169,4 +168,4 @@ start_server {tags {"pubsubshard external:skip"}} {
         assert_equal {smessage chan1 world} [$rd1 read]
     }
 }
-}
+}