[openssl-dev] DTLS session resumption with DTLS_ANY_VERSION

[Rajeswari K]

Hello openssl-dev team,

Having query regarding DTLS session resumption when configured SSL_CTX with
DTLS_ANY_VERSION.

When we select SSL_CTX with DTLS_ANY_VERSION, method will be of
DTLS_Server_method(), which will have ssl_ctx->version as 0xFEFD to support
both the versions (i.e. DTLS1.0 and DTLS1.2).

During handshake, we landed on to version DTLS1.0.i.e. s->session->version
holds 0xFEFF.

In order to perform session resumption, we derived new SSL structure from
global ssl_ctx using SSL_new() and tried performing ssl handshake.

With the below logic,
else {
        i = ssl_get_prev_session(s, p, j, d + n);
        /*
         * Only resume if the session's version matches the negotiated
         * version.
         * RFC 5246 does not provide much useful advice on resumption
         * with a different protocol version. It doesn't forbid it but
         * the sanity of such behaviour would be questionable.
         * In practice, clients do not accept a version mismatch and
         * will abort the handshake with an error.
         */
        if (i == 1 && s->version == s->session->ssl_version) { /* previous
                                                                * session */
            s->hit = 1;
        } else if (i == -1)
            goto err;
        else {                  /* i == 0 */

            if (!ssl_get_new_session(s, 1))
                goto err;
        }

Since s->version is with 0xFEFD and s->session->ssl_version is 0xFEFF, we
always try for new session and wont land on to session resumption though
client has sent the  session_id.

Is this intended behaviour? Please clarify.

Thanks,
Rajeswari.
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