Client tracking tracking-redir-broken push len is 2 not 3 (#8456)

When redis responds with tracking-redir-broken push message (RESP3),
it was responding with a broken protocol: an array of 3 elements, but only
pushes 2 elements.

Some bugs in the test make this pass. Read the push reply
will consume an extra reply, because the reply length is 3, but there
are only two elements, so the next reply will be treated as third
element. So the test is corrected too.

Other changes:
* checkPrefixCollisionsOrReply success should return 1 instead of -1,
  this bug didn't have any implications.
* improve client tracking tests to validate more of the response it reads.

3 files changed, 87 insertions, 39 deletions

diff --git a/src/tracking.c b/src/tracking.c
index 1cf226e52..a11e4b7d7 100644
--- a/src/tracking.c
+++ b/src/tracking.c
@@ -147,7 +147,7 @@ int checkPrefixCollisionsOrReply(client *c, robj **prefixes, size_t numprefix) {
             }
         }
     }
-    return -1;
+    return 1;
 }
 
 /* Set the client 'c' to track the prefix 'prefix'. If the client 'c' is
@@ -269,7 +269,7 @@ void sendTrackingMessage(client *c, char *keyname, size_t keylen, int proto) {
              * are unable to send invalidation messages to the redirected
              * connection, because the client no longer exist. */
             if (c->resp > 2) {
-                addReplyPushLen(c,3);
+                addReplyPushLen(c,2);
                 addReplyBulkCBuffer(c,"tracking-redir-broken",21);
                 addReplyLongLong(c,c->client_tracking_redirection);
             }
diff --git a/tests/support/redis.tcl b/tests/support/redis.tcl
index 54b49920d..373058daf 100644
--- a/tests/support/redis.tcl
+++ b/tests/support/redis.tcl
@@ -248,6 +248,7 @@ proc ::redis::redis_read_reply {id fd} {
         - {return -code error [redis_read_line $fd]}
         $ {redis_bulk_read $fd}
         > -
+        ~ -
         * {redis_multi_bulk_read $id $fd}
         % {redis_read_map $id $fd}
         default {
diff --git a/tests/unit/tracking.tcl b/tests/unit/tracking.tcl
index 7aaca47ca..40f1a2a66 100644
--- a/tests/unit/tracking.tcl
+++ b/tests/unit/tracking.tcl
@@ -17,6 +17,10 @@ start_server {tags {"tracking network"}} {
 
     proc clean_all {} {
         uplevel {
+            # We should make r TRACKING off first. If r is in RESP3,
+            # r FLUSH ALL will send us tracking-redir-broken or other
+            # info which will not be consumed.
+            r CLIENT TRACKING off
             $rd QUIT
             $rd_redirection QUIT
             set rd [redis_deferring_client]
@@ -26,7 +30,6 @@ start_server {tags {"tracking network"}} {
             $rd_redirection subscribe __redis__:invalidate
             $rd_redirection read ; # Consume the SUBSCRIBE reply.
             r FLUSHALL
-            r CLIENT TRACKING off
             r HELLO 2
             r config set tracking-table-max-keys 1000000
         }
@@ -52,7 +55,7 @@ start_server {tags {"tracking network"}} {
         # so that we can check for leaks, as a side effect.
         r MGET a b c d e f g
         r CLIENT TRACKING off
-    }
+    } {*OK}
 
     test {Clients can enable the BCAST mode with the empty prefix} {
         r CLIENT TRACKING on BCAST REDIRECT $redir_id
@@ -72,6 +75,8 @@ start_server {tags {"tracking network"}} {
         r INCR a:2
         r INCR b:1
         r INCR b:2
+        # we should not get this key
+        r INCR c:1
         r EXEC
         # Because of the internals, we know we are going to receive
         # two separated notifications for the two different prefixes.
@@ -96,7 +101,7 @@ start_server {tags {"tracking network"}} {
         r SET loopkey 1 ; # We should not get this
         $rd_sg SET otherkey2 1; # We should get this
         # Because of the internals, we know we are going to receive
-        # two separated notifications for the two different prefixes.
+        # two separated notifications for the two different keys.
         set keys1 [lsort [lindex [$rd_redirection read] 2]]
         set keys2 [lsort [lindex [$rd_redirection read] 2]]
         set keys [lsort [list {*}$keys1 {*}$keys2]]
@@ -109,8 +114,8 @@ start_server {tags {"tracking network"}} {
         $rd_sg SET otherkey1 1; # We should get this
         r SET loopkey 1 ; # We should not get this
         $rd_sg SET otherkey2 1; # We should get this
-        # Because of the internals, we know we are going to receive
-        # two separated notifications for the two different prefixes.
+        # Because $rd_sg send command synchronously, we know we are
+        # going to receive two separated notifications.
         set keys1 [lsort [lindex [$rd_redirection read] 2]]
         set keys2 [lsort [lindex [$rd_redirection read] 2]]
         set keys [lsort [list {*}$keys1 {*}$keys2]]
@@ -123,10 +128,7 @@ start_server {tags {"tracking network"}} {
         r SET mykey myval px 1
         r SET mykeyotherkey myval ; # We should not get it
         after 1000
-        # Because of the internals, we know we are going to receive
-        # two separated notifications for the two different prefixes.
-        set keys1 [lsort [lindex [$rd_redirection read] 2]]
-        set keys [lsort [list {*}$keys1]]
+        set keys [lsort [lindex [$rd_redirection read] 2]]
         assert {$keys eq {mykey}}
     }
 
@@ -172,6 +174,7 @@ start_server {tags {"tracking network"}} {
     }
 
     test {Invalidations of previous keys can be redirected after switching to RESP3} {
+        r HELLO 2
         $rd_sg SET key1 1
         r GET key1
         r HELLO 3
@@ -194,28 +197,33 @@ start_server {tags {"tracking network"}} {
         $rd_sg SET key1 1
         r GET key1
         $rd_redirection QUIT
+        assert_equal OK [$rd_redirection read]
         $rd_sg SET key1 2
         set MAX_TRIES 100
-        for {set i 0} {$i <= $MAX_TRIES && $res <= 0} {incr i} {
+        set res -1
+        for {set i 0} {$i <= $MAX_TRIES && $res < 0} {incr i} {
             set res [lsearch -exact [r PING] "tracking-redir-broken"]
         }
         assert {$res >= 0}
-    }
+        # Consume PING reply
+        assert_equal PONG [r read]
 
-    test {Different clients can redirect to the same connection} {
         # Reinstantiating after QUIT
         set rd_redirection [redis_deferring_client]
         $rd_redirection CLIENT ID
         set redir_id [$rd_redirection read]
         $rd_redirection SUBSCRIBE __redis__:invalidate
         $rd_redirection read ; # Consume the SUBSCRIBE reply
+    }
+
+    test {Different clients can redirect to the same connection} {
         r CLIENT TRACKING on REDIRECT $redir_id
         $rd CLIENT TRACKING on REDIRECT $redir_id 
-        $rd read ; # Consume the TRACKING reply
+        assert_equal OK [$rd read] ; # Consume the TRACKING reply
         $rd_sg MSET key1 1 key2 1
         r GET key1
         $rd GET key2 
-        $rd read ; # Consume the GET reply
+        assert_equal 1 [$rd read] ; # Consume the GET reply
         $rd_sg INCR key1
         $rd_sg INCR key2
         set res1 [lindex [$rd_redirection read] 2]
@@ -226,18 +234,19 @@ start_server {tags {"tracking network"}} {
 
     test {Different clients using different protocols can track the same key} {
         $rd HELLO 3 
-        $rd read ; # Consume the HELLO reply
+        set reply [$rd read] ; # Consume the HELLO reply
+        assert_equal 3 [dict get $reply proto]
         $rd CLIENT TRACKING on 
-        $rd read ; # Consume the TRACKING reply
+        assert_equal OK [$rd read] ; # Consume the TRACKING reply
         $rd_sg set key1 1
         r GET key1
         $rd GET key1 
-        $rd read ; # Consume the GET reply
+        assert_equal 1 [$rd read] ; # Consume the GET reply
         $rd_sg INCR key1
         set res1 [lindex [$rd_redirection read] 2]
         $rd PING ; # Non redirecting client has to talk to the server in order to get invalidation message
         set res2 [lindex [split [$rd read] " "] 1] 
-        $rd read ; # Consume the PING reply, which comes together with the invalidation message
+        assert_equal PONG [$rd read] ; # Consume the PING reply, which comes together with the invalidation message
         assert {$res1 eq {key1}}
         assert {$res2 eq {key1}}
     }
@@ -292,35 +301,36 @@ start_server {tags {"tracking network"}} {
 
     test {Able to redirect to a RESP3 client} {
         $rd_redirection UNSUBSCRIBE __redis__:invalidate ; # Need to unsub first before we can do HELLO 3
-        $rd_redirection read ; # Consume the UNSUBSCRIBE reply
+        set res [$rd_redirection read] ; # Consume the UNSUBSCRIBE reply
+        assert_equal {__redis__:invalidate} [lindex $res 1]
         $rd_redirection HELLO 3
-        $rd_redirection read ; # Consume the HELLO reply
+        set res [$rd_redirection read] ; # Consume the HELLO reply
+        assert_equal [dict get $reply proto] 3
         $rd_redirection SUBSCRIBE __redis__:invalidate
-        $rd_redirection read ; # Consume the SUBSCRIBE reply
+        set res [$rd_redirection read] ; # Consume the SUBSCRIBE reply
+        assert_equal {__redis__:invalidate} [lindex $res 1]
         r CLIENT TRACKING on REDIRECT $redir_id
         $rd_sg SET key1 1
         r GET key1
         $rd_sg INCR key1
         set res [lindex [$rd_redirection read] 1]
         assert {$res eq {key1}}
+        $rd_redirection HELLO 2
+        set res [$rd_redirection read] ; # Consume the HELLO reply
+        assert_equal [dict get $res proto] 2
     }
 
     test {After switching from normal tracking to BCAST mode, no invalidation message is produced for pre-BCAST keys} {
-        $rd HELLO 3
-        $rd read ; # Consume the HELLO reply
-        $rd CLIENT TRACKING on
-        $rd read ; # Consume the TRACKING reply
+        r CLIENT TRACKING off
+        r HELLO 3
+        r CLIENT TRACKING on
         $rd_sg SET key1 1
-        $rd GET key1
-        $rd read ; # Consume the GET reply
-        $rd CLIENT TRACKING off 
-        $rd read ; # Consume the TRACKING reply
-        $rd CLIENT TRACKING on BCAST
-        $rd read ; # Consume the TRACKING reply
+        r GET key1
+        r CLIENT TRACKING off 
+        r CLIENT TRACKING on BCAST
         $rd_sg INCR key1
-        $rd PING
-        set inv_msg [$rd read]
-        set ping_reply [$rd read]
+        set inv_msg [r PING]
+        set ping_reply [r read]
         assert {$inv_msg eq {invalidate key1}}
         assert {$ping_reply eq {PONG}}
     }
@@ -344,7 +354,6 @@ start_server {tags {"tracking network"}} {
     }
 
     test {Tracking gets notification on tracking table key eviction} {
-        $rd_redirection HELLO 2
         r CLIENT TRACKING off
         r CLIENT TRACKING on REDIRECT $redir_id NOLOOP
         r MSET key1 1 key2 2
@@ -368,7 +377,6 @@ start_server {tags {"tracking network"}} {
 
     test {Invalidation message received for flushall} {
         clean_all
-        r CLIENT TRACKING off
         r CLIENT TRACKING on REDIRECT $redir_id
         $rd_sg SET key1 1
         r GET key1
@@ -379,7 +387,6 @@ start_server {tags {"tracking network"}} {
 
     test {Invalidation message received for flushdb} {
         clean_all
-        r CLIENT TRACKING off
         r CLIENT TRACKING on REDIRECT $redir_id
         $rd_sg SET key1 1
         r GET key1
@@ -422,15 +429,29 @@ start_server {tags {"tracking network"}} {
         r GET key1 
         r GET key2
         $rd CLIENT TRACKING on BCAST PREFIX prefix:
+        assert [string match *OK* [$rd read]]
         $rd_sg SET prefix:key1 1 
         $rd_sg SET prefix:key2 2
         set info [r info]
         regexp "\r\ntracking_total_items:(.*?)\r\n" $info _ total_items
         regexp "\r\ntracking_total_keys:(.*?)\r\n" $info _ total_keys
         regexp "\r\ntracking_total_prefixes:(.*?)\r\n" $info _ total_prefixes
+        regexp "\r\ntracking_clients:(.*?)\r\n" $info _ tracking_clients
         assert {$total_items == 2}
         assert {$total_keys == 2}
         assert {$total_prefixes == 1}
+        assert {$tracking_clients == 2}
+    }
+
+    test {CLIENT GETREDIR provides correct client id} {
+        set res [r CLIENT GETREDIR]
+        assert_equal $redir_id $res
+        r CLIENT TRACKING off
+        set res [r CLIENT GETREDIR]
+        assert_equal -1 $res
+        r CLIENT TRACKING on
+        set res [r CLIENT GETREDIR]
+        assert_equal 0 $res
     }
 
     test {CLIENT TRACKINGINFO provides reasonable results when tracking off} {
@@ -510,6 +531,32 @@ start_server {tags {"tracking network"}} {
         assert_equal {0} $redirect
         set prefixes [lsort [dict get $res prefixes]]
         assert_equal {bar foo} $prefixes
+
+        r CLIENT TRACKING off
+        r CLIENT TRACKING on BCAST
+        set res [r client trackinginfo]
+        set prefixes [dict get $res prefixes]
+        assert_equal {{}} $prefixes
+    }
+
+    test {CLIENT TRACKINGINFO provides reasonable results when tracking redir broken} {
+        clean_all
+        r HELLO 3
+        r CLIENT TRACKING on REDIRECT $redir_id
+        $rd_sg SET key1 1
+        r GET key1
+        $rd_redirection QUIT
+        assert_equal OK [$rd_redirection read]
+        $rd_sg SET key1 2
+        set res [lsearch -exact [r read] "tracking-redir-broken"]
+        assert {$res >= 0}
+        set res [r client trackinginfo]
+        set flags [dict get $res flags]
+        assert_equal {on broken_redirect} $flags
+        set redirect [dict get $res redirect]
+        assert_equal $redir_id $redirect
+        set prefixes [dict get $res prefixes]
+        assert_equal {} $prefixes
     }
 
     $rd_redirection close