Tighten session ticket handling

[openssl.git] / ssl / ssl_sess.c

diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index 73d87fd6c1a3c3088606370d04e04d1473b2fb62..3f9bad10a4d3769df4b6bb7eacfcdef45ed355db 100644 (file)
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -340,7 +340,21 @@ int ssl_get_new_session(SSL *s, int session)
                        return(0);
                        }
 #ifndef OPENSSL_NO_TLSEXT
-               /* If RFC4507 ticket use empty session ID */
+               /*
+                * If RFC5077 ticket, use empty session ID (as server).
+                * Note that:
+                * (a) ssl_get_prev_session() does lookahead into the
+                *     ClientHello extensions to find the session ticket.
+                *     When ssl_get_prev_session() fails, s3_srvr.c calls
+                *     ssl_get_new_session() in ssl3_get_client_hello().
+                *     At that point, it has not yet parsed the extensions,
+                *     however, because of the lookahead, it already knows
+                *     whether a ticket is expected or not.
+                *
+                * (b) s3_clnt.c calls ssl_get_new_session() before parsing
+                *     ServerHello extensions, and before recording the session
+                *     ID received from the server, so this block is a noop.
+                */
                if (s->tlsext_ticket_expected)
                        {
                        ss->session_id_length = 0;