RT2772: accept empty SessionTicket

RFC 5077 section 3.3 says:
If the server determines that it does not want to include a
ticket after it has included the SessionTicket extension in the
ServerHello, then it sends a zero-length ticket in the
NewSessionTicket handshake message.

Previously the client would fail upon attempting to allocate a
zero-length buffer. Now, we have the client ignore the empty ticket and
keep the existing session.

Reviewed-by: Matt Caswell <matt@openssl.org>
This commit is contained in:
Emilia Kasper 2015-09-10 16:32:51 +02:00
parent 51cbee3516
commit e711da714b

View file

@ -2195,6 +2195,7 @@ int ssl3_get_new_session_ticket(SSL *s)
{
int ok, al, ret = 0;
unsigned int ticklen;
unsigned long ticket_lifetime_hint;
long n;
PACKET pkt;
@ -2212,6 +2213,18 @@ int ssl3_get_new_session_ticket(SSL *s)
goto f_err;
}
if (!PACKET_get_net_4(&pkt, &ticket_lifetime_hint)
|| !PACKET_get_net_2(&pkt, &ticklen)
|| PACKET_remaining(&pkt) != ticklen) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, SSL_R_LENGTH_MISMATCH);
goto f_err;
}
/* Server is allowed to change its mind and send an empty ticket. */
if (ticklen == 0)
return 1;
if (s->session->session_id_length > 0) {
int i = s->session_ctx->session_cache_mode;
SSL_SESSION *new_sess;
@ -2243,15 +2256,9 @@ int ssl3_get_new_session_ticket(SSL *s)
s->session = new_sess;
}
if (!PACKET_get_net_4(&pkt, &s->session->tlsext_tick_lifetime_hint)
|| !PACKET_get_net_2(&pkt, &ticklen)
|| PACKET_remaining(&pkt) != ticklen) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, SSL_R_LENGTH_MISMATCH);
goto f_err;
}
OPENSSL_free(s->session->tlsext_tick);
s->session->tlsext_ticklen = 0;
s->session->tlsext_tick = OPENSSL_malloc(ticklen);
if (!s->session->tlsext_tick) {
SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, ERR_R_MALLOC_FAILURE);
@ -2262,6 +2269,8 @@ int ssl3_get_new_session_ticket(SSL *s)
SSLerr(SSL_F_SSL3_GET_NEW_SESSION_TICKET, SSL_R_LENGTH_MISMATCH);
goto f_err;
}
s->session->tlsext_tick_lifetime_hint = ticket_lifetime_hint;
s->session->tlsext_ticklen = ticklen;
/*
* There are two ways to detect a resumed ticket session. One is to set