From 266f616ada6ba7de6ae4f34bd450d8b1c0b9d93f Mon Sep 17 00:00:00 2001
From: Neil Twigg <neil@nats.io>
Date: Fri, 3 Jan 2025 15:43:33 +0000
Subject: [PATCH] Use `Nats-TTL: never` for never expires

Signed-off-by: Neil Twigg <neil@nats.io>
---
 server/jetstream_test.go |  2 +-
 server/stream.go         | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/server/jetstream_test.go b/server/jetstream_test.go
index 67a1f997d6..bb983017b4 100644
--- a/server/jetstream_test.go
+++ b/server/jetstream_test.go
@@ -25029,7 +25029,7 @@ func TestJetStreamMessageTTLNeverExpire(t *testing.T) {
 
 	// The first message we publish is set to "never expire", therefore it
 	// won't age out with the MaxAge policy.
-	msg.Header.Set("Nats-TTL", "-1")
+	msg.Header.Set("Nats-TTL", "never")
 	_, err := js.PublishMsg(msg)
 	require_NoError(t, err)
 
diff --git a/server/stream.go b/server/stream.go
index 5d56881838..511039f8a3 100644
--- a/server/stream.go
+++ b/server/stream.go
@@ -4215,6 +4215,9 @@ func getMessageTTL(hdr []byte) (int64, error) {
 		return 0, nil
 	}
 	sttl := bytesToString(ttl)
+	if strings.ToLower(sttl) == "never" {
+		return -1, nil
+	}
 	dur, err := time.ParseDuration(sttl)
 	if err == nil {
 		if dur < time.Second {
@@ -4222,7 +4225,15 @@ func getMessageTTL(hdr []byte) (int64, error) {
 		}
 		return int64(dur.Seconds()), nil
 	}
-	return parseInt64(ttl), nil
+	t := parseInt64(ttl)
+	if t < 0 {
+		// This probably means a parse failure, hence why
+		// we have a special case "never" for returning -1.
+		// Otherwise we can't know if it's a genuine TTL
+		// that says never expire or if it's a parse error.
+		return 0, NewJSMessageTTLInvalidError()
+	}
+	return t, nil
 }
 
 // Signal if we are clustered. Will acquire rlock.