Commit e711da71 authored by Emilia Kasper's avatar Emilia Kasper
Browse files

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: default avatarMatt Caswell <matt@openssl.org>
parent 51cbee35

ssl/s3_clnt.c

+16 −7
Original line number Diff line number Diff line
@@ -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