int WPACKET_reserve_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)
{
/* Internal API, so should not fail */
if (!ossl_assert(pkt->subs != NULL && len != 0))
return 0;
if (pkt->maxsize - pkt->written < len)
return 0;
if (pkt->staticbuf == NULL && (pkt->buf->length - pkt->written < len)) {
size_t newlen;
size_t reflen;
reflen = (len > pkt->buf->length) ? len : pkt->buf->length;
if (reflen > SIZE_MAX / 2) {
newlen = SIZE_MAX;
} else {
newlen = reflen * 2;
if (newlen < DEFAULT_BUF_SIZE)
newlen = DEFAULT_BUF_SIZE;
}
if (BUF_MEM_grow(pkt->buf, newlen) == 0)
return 0;
}
if (allocbytes != NULL)
*allocbytes = WPACKET_get_curr(pkt);
return 1;
}
/*
* Construct the pre_shared_key extension
*/
int tls_construct_ctos_psk(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al)
{
#ifndef OPENSSL_NO_TLS1_3
uint32_t now, agesec, agems;
size_t hashsize, binderoffset, msglen;
unsigned char *binder = NULL, *msgstart = NULL;
const EVP_MD *md;
int ret = 0;
s->session->ext.tick_identity = TLSEXT_PSK_BAD_IDENTITY;
/*
* If this is an incompatible or new session then we have nothing to resume
* so don't add this extension.
*/
if (s->session->ssl_version != TLS1_3_VERSION
|| s->session->ext.ticklen == 0)
return 1;
if (s->session->cipher == NULL) {
SSLerr(SSL_F_TLS_CONSTRUCT_CTOS_PSK, ERR_R_INTERNAL_ERROR);
goto err;
}
md = ssl_md(s->session->cipher->algorithm2);
if (md == NULL) {
/* Don't recognise this cipher so we can't use the session. Ignore it */
return 1;
}
/*
* Technically the C standard just says time() returns a time_t and says
* nothing about the encoding of that type. In practice most implementations
* follow POSIX which holds it as an integral type in seconds since epoch.
* We've already made the assumption that we can do this in multiple places
* in the code, so portability shouldn't be an issue.
*/
now = (uint32_t)time(NULL);
agesec = now - (uint32_t)s->session->time;
if (s->session->ext.tick_lifetime_hint < agesec) {
/* Ticket is too old. Ignore it. */
return 1;
}
/*
* Calculate age in ms. We're just doing it to nearest second. Should be
* good enough.
*/
agems = agesec * (uint32_t)1000;
if (agesec != 0 && agems / (uint32_t)1000 != agesec) {
/*
* Overflow. Shouldn't happen unless this is a *really* old session. If
* so we just ignore it.
*/
return 1;
}
/*
* Obfuscate the age. Overflow here is fine, this addition is supposed to
* be mod 2^32.
*/
agems += s->session->ext.tick_age_add;
hashsize = EVP_MD_size(md);
/* Create the extension, but skip over the binder for now */
if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_psk)
|| !WPACKET_start_sub_packet_u16(pkt)
|| !WPACKET_start_sub_packet_u16(pkt)
|| !WPACKET_sub_memcpy_u16(pkt, s->session->ext.tick,
s->session->ext.ticklen)
|| !WPACKET_put_bytes_u32(pkt, agems)
|| !WPACKET_close(pkt)
|| !WPACKET_get_total_written(pkt, &binderoffset)
|| !WPACKET_start_sub_packet_u16(pkt)
|| !WPACKET_sub_allocate_bytes_u8(pkt, hashsize, &binder)
|| !WPACKET_close(pkt)
|| !WPACKET_close(pkt)
|| !WPACKET_get_total_written(pkt, &msglen)
/*
* We need to fill in all the sub-packet lengths now so we can
* calculate the HMAC of the message up to the binders
*/
|| !WPACKET_fill_lengths(pkt)) {
SSLerr(SSL_F_TLS_CONSTRUCT_CTOS_PSK, ERR_R_INTERNAL_ERROR);
goto err;
}
msgstart = WPACKET_get_curr(pkt) - msglen;
if (tls_psk_do_binder(s, md, msgstart, binderoffset, NULL, binder,
s->session, 1) != 1) {
SSLerr(SSL_F_TLS_CONSTRUCT_CTOS_PSK, ERR_R_INTERNAL_ERROR);
goto err;
}
s->session->ext.tick_identity = 0;
ret = 1;
err:
return ret;
#else
return 1;
#endif
}
