Send supported_versions in an HRR
[openssl.git] / ssl / statem / extensions_clnt.c
index f51a2de..f357396 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2016-2017 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * https://www.openssl.org/source/license.html
  */
 
-#include <assert.h>
+#include <openssl/ocsp.h>
 #include "../ssl_locl.h"
+#include "internal/cryptlib.h"
 #include "statem_locl.h"
 
+EXT_RETURN tls_construct_ctos_renegotiate(SSL *s, WPACKET *pkt,
+                                          unsigned int context, X509 *x,
+                                          size_t chainidx)
+{
+    /* Add RI if renegotiating */
+    if (!s->renegotiate)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_renegotiate)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_sub_memcpy_u8(pkt, s->s3->previous_client_finished,
+                               s->s3->previous_client_finished_len)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_RENEGOTIATE,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+EXT_RETURN tls_construct_ctos_server_name(SSL *s, WPACKET *pkt,
+                                          unsigned int context, X509 *x,
+                                          size_t chainidx)
+{
+    if (s->ext.hostname == NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    /* Add TLS extension servername to the Client Hello message */
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_server_name)
+               /* Sub-packet for server_name extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+               /* Sub-packet for servername list (always 1 hostname)*/
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u8(pkt, TLSEXT_NAMETYPE_host_name)
+            || !WPACKET_sub_memcpy_u16(pkt, s->ext.hostname,
+                                       strlen(s->ext.hostname))
+            || !WPACKET_close(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_SERVER_NAME,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+/* Push a Max Fragment Len extension into ClientHello */
+EXT_RETURN tls_construct_ctos_maxfragmentlen(SSL *s, WPACKET *pkt,
+                                             unsigned int context, X509 *x,
+                                             size_t chainidx)
+{
+    if (s->ext.max_fragment_len_mode == TLSEXT_max_fragment_length_DISABLED)
+        return EXT_RETURN_NOT_SENT;
+
+    /* Add Max Fragment Length extension if client enabled it. */
+    /*-
+     * 4 bytes for this extension type and extension length
+     * 1 byte for the Max Fragment Length code value.
+     */
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_max_fragment_length)
+            /* Sub-packet for Max Fragment Length extension (1 byte) */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u8(pkt, s->ext.max_fragment_len_mode)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_MAXFRAGMENTLEN, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+#ifndef OPENSSL_NO_SRP
+EXT_RETURN tls_construct_ctos_srp(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+    /* Add SRP username if there is one */
+    if (s->srp_ctx.login == NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_srp)
+               /* Sub-packet for SRP extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u8(pkt)
+               /* login must not be zero...internal error if so */
+            || !WPACKET_set_flags(pkt, WPACKET_FLAGS_NON_ZERO_LENGTH)
+            || !WPACKET_memcpy(pkt, s->srp_ctx.login,
+                               strlen(s->srp_ctx.login))
+            || !WPACKET_close(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_SRP,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+#endif
+
+#ifndef OPENSSL_NO_EC
+static int use_ecc(SSL *s)
+{
+    int i, end;
+    unsigned long alg_k, alg_a;
+    STACK_OF(SSL_CIPHER) *cipher_stack = NULL;
+
+    /* See if we support any ECC ciphersuites */
+    if (s->version == SSL3_VERSION)
+        return 0;
+
+    cipher_stack = SSL_get_ciphers(s);
+    end = sk_SSL_CIPHER_num(cipher_stack);
+    for (i = 0; i < end; i++) {
+        const SSL_CIPHER *c = sk_SSL_CIPHER_value(cipher_stack, i);
+
+        alg_k = c->algorithm_mkey;
+        alg_a = c->algorithm_auth;
+        if ((alg_k & (SSL_kECDHE | SSL_kECDHEPSK))
+                || (alg_a & SSL_aECDSA)
+                || c->min_tls >= TLS1_3_VERSION)
+            return 1;
+    }
+
+    return 0;
+}
+
+EXT_RETURN tls_construct_ctos_ec_pt_formats(SSL *s, WPACKET *pkt,
+                                            unsigned int context, X509 *x,
+                                            size_t chainidx)
+{
+    const unsigned char *pformats;
+    size_t num_formats;
+
+    if (!use_ecc(s))
+        return EXT_RETURN_NOT_SENT;
+
+    /* Add TLS extension ECPointFormats to the ClientHello message */
+    tls1_get_formatlist(s, &pformats, &num_formats);
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_ec_point_formats)
+               /* Sub-packet for formats extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_sub_memcpy_u8(pkt, pformats, num_formats)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_EC_PT_FORMATS, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+EXT_RETURN tls_construct_ctos_supported_groups(SSL *s, WPACKET *pkt,
+                                               unsigned int context, X509 *x,
+                                               size_t chainidx)
+{
+    const uint16_t *pgroups = NULL;
+    size_t num_groups = 0, i;
+
+    if (!use_ecc(s))
+        return EXT_RETURN_NOT_SENT;
+
+    /*
+     * Add TLS extension supported_groups to the ClientHello message
+     */
+    /* TODO(TLS1.3): Add support for DHE groups */
+    tls1_get_supported_groups(s, &pgroups, &num_groups);
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_supported_groups)
+               /* Sub-packet for supported_groups extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u16(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_GROUPS,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+    /* Copy curve ID if supported */
+    for (i = 0; i < num_groups; i++) {
+        uint16_t ctmp = pgroups[i];
+
+        if (tls_curve_allowed(s, ctmp, SSL_SECOP_CURVE_SUPPORTED)) {
+            if (!WPACKET_put_bytes_u16(pkt, ctmp)) {
+                    SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                             SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_GROUPS,
+                             ERR_R_INTERNAL_ERROR);
+                    return EXT_RETURN_FAIL;
+                }
+        }
+    }
+    if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_GROUPS,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+#endif
+
+EXT_RETURN tls_construct_ctos_session_ticket(SSL *s, WPACKET *pkt,
+                                             unsigned int context, X509 *x,
+                                             size_t chainidx)
+{
+    size_t ticklen;
+
+    if (!tls_use_ticket(s))
+        return EXT_RETURN_NOT_SENT;
+
+    if (!s->new_session && s->session != NULL
+            && s->session->ext.tick != NULL
+            && s->session->ssl_version != TLS1_3_VERSION) {
+        ticklen = s->session->ext.ticklen;
+    } else if (s->session && s->ext.session_ticket != NULL
+               && s->ext.session_ticket->data != NULL) {
+        ticklen = s->ext.session_ticket->length;
+        s->session->ext.tick = OPENSSL_malloc(ticklen);
+        if (s->session->ext.tick == NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_SESSION_TICKET,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+        memcpy(s->session->ext.tick,
+               s->ext.session_ticket->data, ticklen);
+        s->session->ext.ticklen = ticklen;
+    } else {
+        ticklen = 0;
+    }
+
+    if (ticklen == 0 && s->ext.session_ticket != NULL &&
+            s->ext.session_ticket->data == NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_session_ticket)
+            || !WPACKET_sub_memcpy_u16(pkt, s->session->ext.tick, ticklen)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_SESSION_TICKET, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+EXT_RETURN tls_construct_ctos_sig_algs(SSL *s, WPACKET *pkt,
+                                       unsigned int context, X509 *x,
+                                       size_t chainidx)
+{
+    size_t salglen;
+    const uint16_t *salg;
+
+    if (!SSL_CLIENT_USE_SIGALGS(s))
+        return EXT_RETURN_NOT_SENT;
+
+    salglen = tls12_get_psigalgs(s, 1, &salg);
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_signature_algorithms)
+               /* Sub-packet for sig-algs extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+               /* Sub-packet for the actual list */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !tls12_copy_sigalgs(s, pkt, salg, salglen)
+            || !WPACKET_close(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_SIG_ALGS,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+#ifndef OPENSSL_NO_OCSP
+EXT_RETURN tls_construct_ctos_status_request(SSL *s, WPACKET *pkt,
+                                             unsigned int context, X509 *x,
+                                             size_t chainidx)
+{
+    int i;
+
+    /* This extension isn't defined for client Certificates */
+    if (x != NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    if (s->ext.status_type != TLSEXT_STATUSTYPE_ocsp)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_status_request)
+               /* Sub-packet for status request extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u8(pkt, TLSEXT_STATUSTYPE_ocsp)
+               /* Sub-packet for the ids */
+            || !WPACKET_start_sub_packet_u16(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_STATUS_REQUEST, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+    for (i = 0; i < sk_OCSP_RESPID_num(s->ext.ocsp.ids); i++) {
+        unsigned char *idbytes;
+        OCSP_RESPID *id = sk_OCSP_RESPID_value(s->ext.ocsp.ids, i);
+        int idlen = i2d_OCSP_RESPID(id, NULL);
+
+        if (idlen <= 0
+                   /* Sub-packet for an individual id */
+                || !WPACKET_sub_allocate_bytes_u16(pkt, idlen, &idbytes)
+                || i2d_OCSP_RESPID(id, &idbytes) != idlen) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_STATUS_REQUEST,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+    }
+    if (!WPACKET_close(pkt)
+            || !WPACKET_start_sub_packet_u16(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_STATUS_REQUEST, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+    if (s->ext.ocsp.exts) {
+        unsigned char *extbytes;
+        int extlen = i2d_X509_EXTENSIONS(s->ext.ocsp.exts, NULL);
+
+        if (extlen < 0) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_STATUS_REQUEST,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+        if (!WPACKET_allocate_bytes(pkt, extlen, &extbytes)
+                || i2d_X509_EXTENSIONS(s->ext.ocsp.exts, &extbytes)
+                   != extlen) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_STATUS_REQUEST,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+       }
+    }
+    if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_STATUS_REQUEST, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+#endif
+
+#ifndef OPENSSL_NO_NEXTPROTONEG
+EXT_RETURN tls_construct_ctos_npn(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+    if (s->ctx->ext.npn_select_cb == NULL || !SSL_IS_FIRST_HANDSHAKE(s))
+        return EXT_RETURN_NOT_SENT;
+
+    /*
+     * The client advertises an empty extension to indicate its support
+     * for Next Protocol Negotiation
+     */
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_next_proto_neg)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_NPN,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+#endif
+
+EXT_RETURN tls_construct_ctos_alpn(SSL *s, WPACKET *pkt, unsigned int context,
+                                   X509 *x, size_t chainidx)
+{
+    s->s3->alpn_sent = 0;
+
+    if (s->ext.alpn == NULL || !SSL_IS_FIRST_HANDSHAKE(s))
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt,
+                TLSEXT_TYPE_application_layer_protocol_negotiation)
+               /* Sub-packet ALPN extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_sub_memcpy_u16(pkt, s->ext.alpn, s->ext.alpn_len)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_ALPN,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+    s->s3->alpn_sent = 1;
+
+    return EXT_RETURN_SENT;
+}
+
+
+#ifndef OPENSSL_NO_SRTP
+EXT_RETURN tls_construct_ctos_use_srtp(SSL *s, WPACKET *pkt,
+                                       unsigned int context, X509 *x,
+                                       size_t chainidx)
+{
+    STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = SSL_get_srtp_profiles(s);
+    int i, end;
+
+    if (clnt == NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_use_srtp)
+               /* Sub-packet for SRTP extension */
+            || !WPACKET_start_sub_packet_u16(pkt)
+               /* Sub-packet for the protection profile list */
+            || !WPACKET_start_sub_packet_u16(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_USE_SRTP,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    end = sk_SRTP_PROTECTION_PROFILE_num(clnt);
+    for (i = 0; i < end; i++) {
+        const SRTP_PROTECTION_PROFILE *prof =
+            sk_SRTP_PROTECTION_PROFILE_value(clnt, i);
+
+        if (prof == NULL || !WPACKET_put_bytes_u16(pkt, prof->id)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_USE_SRTP, ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+    }
+    if (!WPACKET_close(pkt)
+               /* Add an empty use_mki value */
+            || !WPACKET_put_bytes_u8(pkt, 0)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_USE_SRTP,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+#endif
+
+EXT_RETURN tls_construct_ctos_etm(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+    if (s->options & SSL_OP_NO_ENCRYPT_THEN_MAC)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_encrypt_then_mac)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_ETM,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+#ifndef OPENSSL_NO_CT
+EXT_RETURN tls_construct_ctos_sct(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+    if (s->ct_validation_callback == NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    /* Not defined for client Certificates */
+    if (x != NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_signed_certificate_timestamp)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_SCT,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+#endif
+
+EXT_RETURN tls_construct_ctos_ems(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_extended_master_secret)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_EMS,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+EXT_RETURN tls_construct_ctos_supported_versions(SSL *s, WPACKET *pkt,
+                                                 unsigned int context, X509 *x,
+                                                 size_t chainidx)
+{
+    int currv, min_version, max_version, reason;
+
+    reason = ssl_get_min_max_version(s, &min_version, &max_version);
+    if (reason != 0) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_VERSIONS, reason);
+        return EXT_RETURN_FAIL;
+    }
+
+    /*
+     * Don't include this if we can't negotiate TLSv1.3. We can do a straight
+     * comparison here because we will never be called in DTLS.
+     */
+    if (max_version < TLS1_3_VERSION)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_supported_versions)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u8(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_VERSIONS,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    /*
+     * TODO(TLS1.3): There is some discussion on the TLS list as to whether
+     * we should include versions <TLS1.2. For the moment we do. To be
+     * reviewed later.
+     */
+    for (currv = max_version; currv >= min_version; currv--) {
+        /* TODO(TLS1.3): Remove this first if clause prior to release!! */
+        if (currv == TLS1_3_VERSION) {
+            if (!WPACKET_put_bytes_u16(pkt, TLS1_3_VERSION_DRAFT)) {
+                SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                         SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_VERSIONS,
+                         ERR_R_INTERNAL_ERROR);
+                return EXT_RETURN_FAIL;
+            }
+        } else if (!WPACKET_put_bytes_u16(pkt, currv)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_VERSIONS,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+    }
+    if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_VERSIONS,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+/*
+ * Construct a psk_kex_modes extension.
+ */
+EXT_RETURN tls_construct_ctos_psk_kex_modes(SSL *s, WPACKET *pkt,
+                                            unsigned int context, X509 *x,
+                                            size_t chainidx)
+{
+#ifndef OPENSSL_NO_TLS1_3
+    int nodhe = s->options & SSL_OP_ALLOW_NO_DHE_KEX;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_psk_kex_modes)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u8(pkt)
+            || !WPACKET_put_bytes_u8(pkt, TLSEXT_KEX_MODE_KE_DHE)
+            || (nodhe && !WPACKET_put_bytes_u8(pkt, TLSEXT_KEX_MODE_KE))
+            || !WPACKET_close(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_TLS_CONSTRUCT_CTOS_PSK_KEX_MODES, ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    s->ext.psk_kex_mode = TLSEXT_KEX_MODE_FLAG_KE_DHE;
+    if (nodhe)
+        s->ext.psk_kex_mode |= TLSEXT_KEX_MODE_FLAG_KE;
+#endif
+
+    return EXT_RETURN_SENT;
+}
+
+#ifndef OPENSSL_NO_TLS1_3
+static int add_key_share(SSL *s, WPACKET *pkt, unsigned int curve_id)
+{
+    unsigned char *encoded_point = NULL;
+    EVP_PKEY *key_share_key = NULL;
+    size_t encodedlen;
+
+    if (s->s3->tmp.pkey != NULL) {
+        if (!ossl_assert(s->hello_retry_request == SSL_HRR_PENDING)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_ADD_KEY_SHARE,
+                     ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+        /*
+         * Could happen if we got an HRR that wasn't requesting a new key_share
+         */
+        key_share_key = s->s3->tmp.pkey;
+    } else {
+        key_share_key = ssl_generate_pkey_group(s, curve_id);
+        if (key_share_key == NULL) {
+            /* SSLfatal() already called */
+            return 0;
+        }
+    }
+
+    /* Encode the public key. */
+    encodedlen = EVP_PKEY_get1_tls_encodedpoint(key_share_key,
+                                                &encoded_point);
+    if (encodedlen == 0) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_ADD_KEY_SHARE, ERR_R_EC_LIB);
+        goto err;
+    }
+
+    /* Create KeyShareEntry */
+    if (!WPACKET_put_bytes_u16(pkt, curve_id)
+            || !WPACKET_sub_memcpy_u16(pkt, encoded_point, encodedlen)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_ADD_KEY_SHARE,
+                 ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
+
+    /*
+     * TODO(TLS1.3): When changing to send more than one key_share we're
+     * going to need to be able to save more than one EVP_PKEY. For now
+     * we reuse the existing tmp.pkey
+     */
+    s->s3->tmp.pkey = key_share_key;
+    s->s3->group_id = curve_id;
+    OPENSSL_free(encoded_point);
+
+    return 1;
+ err:
+    if (s->s3->tmp.pkey == NULL)
+        EVP_PKEY_free(key_share_key);
+    OPENSSL_free(encoded_point);
+    return 0;
+}
+#endif
+
+EXT_RETURN tls_construct_ctos_key_share(SSL *s, WPACKET *pkt,
+                                        unsigned int context, X509 *x,
+                                        size_t chainidx)
+{
+#ifndef OPENSSL_NO_TLS1_3
+    size_t i, num_groups = 0;
+    const uint16_t *pgroups = NULL;
+    uint16_t curve_id = 0;
+
+    /* key_share extension */
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_key_share)
+               /* Extension data sub-packet */
+            || !WPACKET_start_sub_packet_u16(pkt)
+               /* KeyShare list sub-packet */
+            || !WPACKET_start_sub_packet_u16(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_KEY_SHARE,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    tls1_get_supported_groups(s, &pgroups, &num_groups);
+
+    /*
+     * TODO(TLS1.3): Make the number of key_shares sent configurable. For
+     * now, just send one
+     */
+    if (s->s3->group_id != 0) {
+        curve_id = s->s3->group_id;
+    } else {
+        for (i = 0; i < num_groups; i++) {
+
+            if (!tls_curve_allowed(s, pgroups[i], SSL_SECOP_CURVE_SUPPORTED))
+                continue;
+
+            curve_id = pgroups[i];
+            break;
+        }
+    }
+
+    if (curve_id == 0) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_KEY_SHARE,
+                 SSL_R_NO_SUITABLE_KEY_SHARE);
+        return EXT_RETURN_FAIL;
+    }
+
+    if (!add_key_share(s, pkt, curve_id)) {
+        /* SSLfatal() already called */
+        return EXT_RETURN_FAIL;
+    }
+
+    if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_KEY_SHARE,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+#endif
+
+    return EXT_RETURN_SENT;
+}
+
+EXT_RETURN tls_construct_ctos_cookie(SSL *s, WPACKET *pkt, unsigned int context,
+                                     X509 *x, size_t chainidx)
+{
+    EXT_RETURN ret = EXT_RETURN_FAIL;
+
+    /* Should only be set if we've had an HRR */
+    if (s->ext.tls13_cookie_len == 0)
+        return EXT_RETURN_NOT_SENT;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_cookie)
+               /* Extension data sub-packet */
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_sub_memcpy_u16(pkt, s->ext.tls13_cookie,
+                                       s->ext.tls13_cookie_len)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_COOKIE,
+                 ERR_R_INTERNAL_ERROR);
+        goto end;
+    }
+
+    ret = EXT_RETURN_SENT;
+ end:
+    OPENSSL_free(s->ext.tls13_cookie);
+    s->ext.tls13_cookie = NULL;
+    s->ext.tls13_cookie_len = 0;
+
+    return ret;
+}
+
+EXT_RETURN tls_construct_ctos_early_data(SSL *s, WPACKET *pkt,
+                                         unsigned int context, X509 *x,
+                                         size_t chainidx)
+{
+    const unsigned char *id = NULL;
+    size_t idlen = 0;
+    SSL_SESSION *psksess = NULL;
+    SSL_SESSION *edsess = NULL;
+    const EVP_MD *handmd = NULL;
+
+    if (s->hello_retry_request == SSL_HRR_PENDING)
+        handmd = ssl_handshake_md(s);
+
+    if (s->psk_use_session_cb != NULL
+            && (!s->psk_use_session_cb(s, handmd, &id, &idlen, &psksess)
+                || (psksess != NULL
+                    && psksess->ssl_version != TLS1_3_VERSION))) {
+        SSL_SESSION_free(psksess);
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
+                 SSL_R_BAD_PSK);
+        return EXT_RETURN_FAIL;
+    }
+
+    SSL_SESSION_free(s->psksession);
+    s->psksession = psksess;
+    if (psksess != NULL) {
+        OPENSSL_free(s->psksession_id);
+        s->psksession_id = OPENSSL_memdup(id, idlen);
+        if (s->psksession_id == NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA, ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+        s->psksession_id_len = idlen;
+    }
+
+    if (s->early_data_state != SSL_EARLY_DATA_CONNECTING
+            || (s->session->ext.max_early_data == 0
+                && (psksess == NULL || psksess->ext.max_early_data == 0))) {
+        s->max_early_data = 0;
+        return EXT_RETURN_NOT_SENT;
+    }
+    edsess = s->session->ext.max_early_data != 0 ? s->session : psksess;
+    s->max_early_data = edsess->ext.max_early_data;
+
+    if (edsess->ext.hostname != NULL) {
+        if (s->ext.hostname == NULL
+                || (s->ext.hostname != NULL
+                    && strcmp(s->ext.hostname, edsess->ext.hostname) != 0)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
+                     SSL_R_INCONSISTENT_EARLY_DATA_SNI);
+            return EXT_RETURN_FAIL;
+        }
+    }
+
+    if ((s->ext.alpn == NULL && edsess->ext.alpn_selected != NULL)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
+                 SSL_R_INCONSISTENT_EARLY_DATA_ALPN);
+        return EXT_RETURN_FAIL;
+    }
+
+    /*
+     * Verify that we are offering an ALPN protocol consistent with the early
+     * data.
+     */
+    if (edsess->ext.alpn_selected != NULL) {
+        PACKET prots, alpnpkt;
+        int found = 0;
+
+        if (!PACKET_buf_init(&prots, s->ext.alpn, s->ext.alpn_len)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA, ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+        while (PACKET_get_length_prefixed_1(&prots, &alpnpkt)) {
+            if (PACKET_equal(&alpnpkt, edsess->ext.alpn_selected,
+                             edsess->ext.alpn_selected_len)) {
+                found = 1;
+                break;
+            }
+        }
+        if (!found) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
+                     SSL_R_INCONSISTENT_EARLY_DATA_ALPN);
+            return EXT_RETURN_FAIL;
+        }
+    }
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_early_data)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_EARLY_DATA,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    /*
+     * We set this to rejected here. Later, if the server acknowledges the
+     * extension, we set it to accepted.
+     */
+    s->ext.early_data = SSL_EARLY_DATA_REJECTED;
+    s->ext.early_data_ok = 1;
+
+    return EXT_RETURN_SENT;
+}
+
+#define F5_WORKAROUND_MIN_MSG_LEN   0xff
+#define F5_WORKAROUND_MAX_MSG_LEN   0x200
+
+/*
+ * PSK pre binder overhead =
+ *  2 bytes for TLSEXT_TYPE_psk
+ *  2 bytes for extension length
+ *  2 bytes for identities list length
+ *  2 bytes for identity length
+ *  4 bytes for obfuscated_ticket_age
+ *  2 bytes for binder list length
+ *  1 byte for binder length
+ * The above excludes the number of bytes for the identity itself and the
+ * subsequent binder bytes
+ */
+#define PSK_PRE_BINDER_OVERHEAD (2 + 2 + 2 + 2 + 4 + 2 + 1)
+
+EXT_RETURN tls_construct_ctos_padding(SSL *s, WPACKET *pkt,
+                                      unsigned int context, X509 *x,
+                                      size_t chainidx)
+{
+    unsigned char *padbytes;
+    size_t hlen;
+
+    if ((s->options & SSL_OP_TLSEXT_PADDING) == 0)
+        return EXT_RETURN_NOT_SENT;
+
+    /*
+     * Add padding to workaround bugs in F5 terminators. See RFC7685.
+     * This code calculates the length of all extensions added so far but
+     * excludes the PSK extension (because that MUST be written last). Therefore
+     * this extension MUST always appear second to last.
+     */
+    if (!WPACKET_get_total_written(pkt, &hlen)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PADDING,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    /*
+     * If we're going to send a PSK then that will be written out after this
+     * extension, so we need to calculate how long it is going to be.
+     */
+    if (s->session->ssl_version == TLS1_3_VERSION
+            && s->session->ext.ticklen != 0
+            && s->session->cipher != NULL) {
+        const EVP_MD *md = ssl_md(s->session->cipher->algorithm2);
+
+        if (md != NULL) {
+            /*
+             * Add the fixed PSK overhead, the identity length and the binder
+             * length.
+             */
+            hlen +=  PSK_PRE_BINDER_OVERHEAD + s->session->ext.ticklen
+                     + EVP_MD_size(md);
+        }
+    }
+
+    if (hlen > F5_WORKAROUND_MIN_MSG_LEN && hlen < F5_WORKAROUND_MAX_MSG_LEN) {
+        /* Calculate the amount of padding we need to add */
+        hlen = F5_WORKAROUND_MAX_MSG_LEN - hlen;
+
+        /*
+         * Take off the size of extension header itself (2 bytes for type and
+         * 2 bytes for length bytes), but ensure that the extension is at least
+         * 1 byte long so as not to have an empty extension last (WebSphere 7.x,
+         * 8.x are intolerant of that condition)
+         */
+        if (hlen > 4)
+            hlen -= 4;
+        else
+            hlen = 1;
+
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_padding)
+                || !WPACKET_sub_allocate_bytes_u16(pkt, hlen, &padbytes)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PADDING,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+        memset(padbytes, 0, hlen);
+    }
+
+    return EXT_RETURN_SENT;
+}
+
+/*
+ * Construct the pre_shared_key extension
+ */
+EXT_RETURN tls_construct_ctos_psk(SSL *s, WPACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+#ifndef OPENSSL_NO_TLS1_3
+    uint32_t now, agesec, agems = 0;
+    size_t reshashsize = 0, pskhashsize = 0, binderoffset, msglen;
+    unsigned char *resbinder = NULL, *pskbinder = NULL, *msgstart = NULL;
+    const EVP_MD *handmd = NULL, *mdres = NULL, *mdpsk = NULL;
+    int dores = 0;
+
+    s->session->ext.tick_identity = TLSEXT_PSK_BAD_IDENTITY;
+
+    /*
+     * Note: At this stage of the code we only support adding a single
+     * resumption PSK. If we add support for multiple PSKs then the length
+     * calculations in the padding extension will need to be adjusted.
+     */
+
+    /*
+     * 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 && s->psksession == NULL))
+        return EXT_RETURN_NOT_SENT;
+
+    if (s->hello_retry_request == SSL_HRR_PENDING)
+        handmd = ssl_handshake_md(s);
+
+    if (s->session->ext.ticklen != 0) {
+        /* Get the digest associated with the ciphersuite in the session */
+        if (s->session->cipher == NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+        mdres = ssl_md(s->session->cipher->algorithm2);
+        if (mdres == NULL) {
+            /*
+             * Don't recognize this cipher so we can't use the session.
+             * Ignore it
+             */
+            goto dopsksess;
+        }
+
+        if (s->hello_retry_request == SSL_HRR_PENDING && mdres != handmd) {
+            /*
+             * Selected ciphersuite hash does not match the hash for the session
+             * so we can't use it.
+             */
+            goto dopsksess;
+        }
+
+        /*
+         * 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. */
+            goto dopsksess;
+        }
+
+        /*
+         * 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.
+             */
+            goto dopsksess;
+        }
+
+        /*
+         * Obfuscate the age. Overflow here is fine, this addition is supposed
+         * to be mod 2^32.
+         */
+        agems += s->session->ext.tick_age_add;
+
+        reshashsize = EVP_MD_size(mdres);
+        dores = 1;
+    }
+
+ dopsksess:
+    if (!dores && s->psksession == NULL)
+        return EXT_RETURN_NOT_SENT;
+
+    if (s->psksession != NULL) {
+        mdpsk = ssl_md(s->psksession->cipher->algorithm2);
+        if (mdpsk == NULL) {
+            /*
+             * Don't recognize this cipher so we can't use the session.
+             * If this happens it's an application bug.
+             */
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                     SSL_R_BAD_PSK);
+            return EXT_RETURN_FAIL;
+        }
+
+        if (s->hello_retry_request == SSL_HRR_PENDING && mdpsk != handmd) {
+            /*
+             * Selected ciphersuite hash does not match the hash for the PSK
+             * session. This is an application bug.
+             */
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                     SSL_R_BAD_PSK);
+            return EXT_RETURN_FAIL;
+        }
+
+        pskhashsize = EVP_MD_size(mdpsk);
+    }
+
+    /* 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)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    if (dores) {
+        if (!WPACKET_sub_memcpy_u16(pkt, s->session->ext.tick,
+                                           s->session->ext.ticklen)
+                || !WPACKET_put_bytes_u32(pkt, agems)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+    }
+
+    if (s->psksession != NULL) {
+        if (!WPACKET_sub_memcpy_u16(pkt, s->psksession_id,
+                                    s->psksession_id_len)
+                || !WPACKET_put_bytes_u32(pkt, 0)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                     ERR_R_INTERNAL_ERROR);
+            return EXT_RETURN_FAIL;
+        }
+    }
+
+    if (!WPACKET_close(pkt)
+            || !WPACKET_get_total_written(pkt, &binderoffset)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || (dores
+                && !WPACKET_sub_allocate_bytes_u8(pkt, reshashsize, &resbinder))
+            || (s->psksession != NULL
+                && !WPACKET_sub_allocate_bytes_u8(pkt, pskhashsize, &pskbinder))
+            || !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)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_PSK,
+                 ERR_R_INTERNAL_ERROR);
+        return EXT_RETURN_FAIL;
+    }
+
+    msgstart = WPACKET_get_curr(pkt) - msglen;
+
+    if (dores
+            && tls_psk_do_binder(s, mdres, msgstart, binderoffset, NULL,
+                                 resbinder, s->session, 1, 0) != 1) {
+        /* SSLfatal() already called */
+        return EXT_RETURN_FAIL;
+    }
+
+    if (s->psksession != NULL
+            && tls_psk_do_binder(s, mdpsk, msgstart, binderoffset, NULL,
+                                 pskbinder, s->psksession, 1, 1) != 1) {
+        /* SSLfatal() already called */
+        return EXT_RETURN_FAIL;
+    }
+
+    if (dores)
+        s->session->ext.tick_identity = 0;
+    if (s->psksession != NULL)
+        s->psksession->ext.tick_identity = (dores ? 1 : 0);
+
+    return EXT_RETURN_SENT;
+#else
+    return EXT_RETURN_NOT_SENT;
+#endif
+}
+
 /*
  * Parse the server's renegotiation binding and abort if it's not right
  */
-int tls_parse_server_renegotiate(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_renegotiate(SSL *s, PACKET *pkt, unsigned int context,
+                               X509 *x, size_t chainidx)
 {
     size_t expected_len = s->s3->previous_client_finished_len
         + s->s3->previous_server_finished_len;
@@ -22,48 +1145,49 @@ int tls_parse_server_renegotiate(SSL *s, PACKET *pkt, int *al)
     const unsigned char *data;
 
     /* Check for logic errors */
-    assert(expected_len == 0 || s->s3->previous_client_finished_len != 0);
-    assert(expected_len == 0 || s->s3->previous_server_finished_len != 0);
+    if (!ossl_assert(expected_len == 0
+                     || s->s3->previous_client_finished_len != 0)
+        || !ossl_assert(expected_len == 0
+                        || s->s3->previous_server_finished_len != 0)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_RENEGOTIATE,
+                 ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
 
     /* Parse the length byte */
     if (!PACKET_get_1_len(pkt, &ilen)) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_ENCODING_ERR);
-        *al = SSL_AD_ILLEGAL_PARAMETER;
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_RENEGOTIATE,
+                 SSL_R_RENEGOTIATION_ENCODING_ERR);
         return 0;
     }
 
     /* Consistency check */
     if (PACKET_remaining(pkt) != ilen) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_ENCODING_ERR);
-        *al = SSL_AD_ILLEGAL_PARAMETER;
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_RENEGOTIATE,
+                 SSL_R_RENEGOTIATION_ENCODING_ERR);
         return 0;
     }
 
     /* Check that the extension matches */
     if (ilen != expected_len) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_MISMATCH);
-        *al = SSL_AD_HANDSHAKE_FAILURE;
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_RENEGOTIATE,
+                 SSL_R_RENEGOTIATION_MISMATCH);
         return 0;
     }
 
     if (!PACKET_get_bytes(pkt, &data, s->s3->previous_client_finished_len)
         || memcmp(data, s->s3->previous_client_finished,
                   s->s3->previous_client_finished_len) != 0) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_MISMATCH);
-        *al = SSL_AD_HANDSHAKE_FAILURE;
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_RENEGOTIATE,
+                 SSL_R_RENEGOTIATION_MISMATCH);
         return 0;
     }
 
     if (!PACKET_get_bytes(pkt, &data, s->s3->previous_server_finished_len)
         || memcmp(data, s->s3->previous_server_finished,
                   s->s3->previous_server_finished_len) != 0) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_MISMATCH);
-        *al = SSL_AD_ILLEGAL_PARAMETER;
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_RENEGOTIATE,
+                 SSL_R_RENEGOTIATION_MISMATCH);
         return 0;
     }
     s->s3->send_connection_binding = 1;
@@ -71,21 +1195,73 @@ int tls_parse_server_renegotiate(SSL *s, PACKET *pkt, int *al)
     return 1;
 }
 
-int tls_parse_server_server_name(SSL *s, PACKET *pkt, int *al)
+/* Parse the server's max fragment len extension packet */
+int tls_parse_stoc_maxfragmentlen(SSL *s, PACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
+{
+    unsigned int value;
+
+    if (PACKET_remaining(pkt) != 1 || !PACKET_get_1(pkt, &value)) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_MAXFRAGMENTLEN, 
+                 SSL_R_BAD_EXTENSION);
+        return 0;
+    }
+
+    /* |value| should contains a valid max-fragment-length code. */
+    if (!IS_MAX_FRAGMENT_LENGTH_EXT_VALID(value)) {
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
+                 SSL_F_TLS_PARSE_STOC_MAXFRAGMENTLEN,
+                 SSL_R_SSL3_EXT_INVALID_MAX_FRAGMENT_LENGTH);
+        return 0;
+    }
+
+    /* Must be the same value as client-configured one who was sent to server */
+    /*-
+     * RFC 6066: if a client receives a maximum fragment length negotiation
+     * response that differs from the length it requested, ...
+     * It must abort with SSL_AD_ILLEGAL_PARAMETER alert
+     */
+    if (value != s->ext.max_fragment_len_mode) {
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
+                 SSL_F_TLS_PARSE_STOC_MAXFRAGMENTLEN,
+                 SSL_R_SSL3_EXT_INVALID_MAX_FRAGMENT_LENGTH);
+        return 0;
+    }
+
+    /*
+     * Maximum Fragment Length Negotiation succeeded.
+     * The negotiated Maximum Fragment Length is binding now.
+     */
+    s->session->ext.max_fragment_len_mode = value;
+
+    return 1;
+}
+
+int tls_parse_stoc_server_name(SSL *s, PACKET *pkt, unsigned int context,
+                               X509 *x, size_t chainidx)
 {
-    if (s->tlsext_hostname == NULL || PACKET_remaining(pkt) > 0) {
-        *al = SSL_AD_UNRECOGNIZED_NAME;
+    if (s->ext.hostname == NULL) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_SERVER_NAME,
+                 ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    if (PACKET_remaining(pkt) > 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_SERVER_NAME,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
 
     if (!s->hit) {
-        if (s->session->tlsext_hostname != NULL) {
-            *al = SSL_AD_INTERNAL_ERROR;
+        if (s->session->ext.hostname != NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_SERVER_NAME,
+                     ERR_R_INTERNAL_ERROR);
             return 0;
         }
-        s->session->tlsext_hostname = OPENSSL_strdup(s->tlsext_hostname);
-        if (s->session->tlsext_hostname == NULL) {
-            *al = SSL_AD_INTERNAL_ERROR;
+        s->session->ext.hostname = OPENSSL_strdup(s->ext.hostname);
+        if (s->session->ext.hostname == NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_SERVER_NAME,
+                     ERR_R_INTERNAL_ERROR);
             return 0;
         }
     }
@@ -94,33 +1270,36 @@ int tls_parse_server_server_name(SSL *s, PACKET *pkt, int *al)
 }
 
 #ifndef OPENSSL_NO_EC
-int tls_parse_server_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_ec_pt_formats(SSL *s, PACKET *pkt, unsigned int context,
+                                 X509 *x, size_t chainidx)
 {
-    unsigned int ecpointformatlist_length;
+    unsigned int ecpointformats_len;
     PACKET ecptformatlist;
 
     if (!PACKET_as_length_prefixed_1(pkt, &ecptformatlist)) {
-        *al = SSL_AD_DECODE_ERROR;
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_EC_PT_FORMATS,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
     if (!s->hit) {
-        ecpointformatlist_length = PACKET_remaining(&ecptformatlist);
-        s->session->tlsext_ecpointformatlist_length = 0;
-
-        OPENSSL_free(s->session->tlsext_ecpointformatlist);
-        s->session->tlsext_ecpointformatlist =
-             OPENSSL_malloc(ecpointformatlist_length);
-        if (s->session->tlsext_ecpointformatlist == NULL) {
-            *al = SSL_AD_INTERNAL_ERROR;
+        ecpointformats_len = PACKET_remaining(&ecptformatlist);
+        s->session->ext.ecpointformats_len = 0;
+
+        OPENSSL_free(s->session->ext.ecpointformats);
+        s->session->ext.ecpointformats = OPENSSL_malloc(ecpointformats_len);
+        if (s->session->ext.ecpointformats == NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_PARSE_STOC_EC_PT_FORMATS, ERR_R_INTERNAL_ERROR);
             return 0;
         }
 
-        s->session->tlsext_ecpointformatlist_length = ecpointformatlist_length;
+        s->session->ext.ecpointformats_len = ecpointformats_len;
 
         if (!PACKET_copy_bytes(&ecptformatlist,
-                               s->session->tlsext_ecpointformatlist,
-                               ecpointformatlist_length)) {
-            *al = SSL_AD_INTERNAL_ERROR;
+                               s->session->ext.ecpointformats,
+                               ecpointformats_len)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_TLS_PARSE_STOC_EC_PT_FORMATS, ERR_R_INTERNAL_ERROR);
             return 0;
         }
     }
@@ -129,43 +1308,75 @@ int tls_parse_server_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
 }
 #endif
 
-int tls_parse_server_session_ticket(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_session_ticket(SSL *s, PACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
 {
-    if (s->tls_session_ticket_ext_cb &&
-        !s->tls_session_ticket_ext_cb(s, PACKET_data(pkt),
-                                      PACKET_remaining(pkt),
-                                      s->tls_session_ticket_ext_cb_arg)) {
-        *al = SSL_AD_INTERNAL_ERROR;
+    if (s->ext.session_ticket_cb != NULL &&
+        !s->ext.session_ticket_cb(s, PACKET_data(pkt),
+                              PACKET_remaining(pkt),
+                              s->ext.session_ticket_cb_arg)) {
+        SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE,
+                 SSL_F_TLS_PARSE_STOC_SESSION_TICKET, SSL_R_BAD_EXTENSION);
         return 0;
     }
-    if (!tls_use_ticket(s) || PACKET_remaining(pkt) > 0) {
-        *al = SSL_AD_UNSUPPORTED_EXTENSION;
+
+    if (!tls_use_ticket(s)) {
+        SSLfatal(s, SSL_AD_UNSUPPORTED_EXTENSION,
+                 SSL_F_TLS_PARSE_STOC_SESSION_TICKET, SSL_R_BAD_EXTENSION);
         return 0;
     }
-    s->tlsext_ticket_expected = 1;
+    if (PACKET_remaining(pkt) > 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR,
+                 SSL_F_TLS_PARSE_STOC_SESSION_TICKET, SSL_R_BAD_EXTENSION);
+        return 0;
+    }
+
+    s->ext.ticket_expected = 1;
 
     return 1;
 }
 
-int tls_parse_server_status_request(SSL *s, PACKET *pkt, int *al)
+#ifndef OPENSSL_NO_OCSP
+int tls_parse_stoc_status_request(SSL *s, PACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx)
 {
     /*
-     * MUST be empty and only sent if we've requested a status
-     * request message.
+     * MUST only be sent if we've requested a status
+     * request message. In TLS <= 1.2 it must also be empty.
      */
-    if (s->tlsext_status_type == -1 || PACKET_remaining(pkt) > 0) {
-        *al = SSL_AD_UNSUPPORTED_EXTENSION;
+    if (s->ext.status_type != TLSEXT_STATUSTYPE_ocsp) {
+        SSLfatal(s, SSL_AD_UNSUPPORTED_EXTENSION,
+                 SSL_F_TLS_PARSE_STOC_STATUS_REQUEST, SSL_R_BAD_EXTENSION);
         return 0;
     }
+    if (!SSL_IS_TLS13(s) && PACKET_remaining(pkt) > 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR,
+                 SSL_F_TLS_PARSE_STOC_STATUS_REQUEST, SSL_R_BAD_EXTENSION);
+        return 0;
+    }
+
+    if (SSL_IS_TLS13(s)) {
+        /* We only know how to handle this if it's for the first Certificate in
+         * the chain. We ignore any other responses.
+         */
+        if (chainidx != 0)
+            return 1;
+
+        /* SSLfatal() already called */
+        return tls_process_cert_status_body(s, pkt);
+    }
+
     /* Set flag to expect CertificateStatus message */
-    s->tlsext_status_expected = 1;
+    s->ext.status_expected = 1;
 
     return 1;
 }
+#endif
 
 
 #ifndef OPENSSL_NO_CT
-int tls_parse_server_sct(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_sct(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx)
 {
     /*
      * Only take it if we asked for it - i.e if there is no CT validation
@@ -176,23 +1387,42 @@ int tls_parse_server_sct(SSL *s, PACKET *pkt, int *al)
         size_t size = PACKET_remaining(pkt);
 
         /* Simply copy it off for later processing */
-        if (s->tlsext_scts != NULL) {
-            OPENSSL_free(s->tlsext_scts);
-            s->tlsext_scts = NULL;
-        }
-        s->tlsext_scts_len = size;
+        OPENSSL_free(s->ext.scts);
+        s->ext.scts = NULL;
+
+        s->ext.scts_len = (uint16_t)size;
         if (size > 0) {
-            s->tlsext_scts = OPENSSL_malloc(size);
-            if (s->tlsext_scts == NULL
-                    || !PACKET_copy_bytes(pkt, s->tlsext_scts, size)) {
-                *al = SSL_AD_INTERNAL_ERROR;
+            s->ext.scts = OPENSSL_malloc(size);
+            if (s->ext.scts == NULL
+                    || !PACKET_copy_bytes(pkt, s->ext.scts, size)) {
+                SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_SCT,
+                         ERR_R_INTERNAL_ERROR);
                 return 0;
             }
         }
     } else {
-        if (custom_ext_parse(s, 0, TLSEXT_TYPE_signed_certificate_timestamp,
-                             PACKET_data(pkt), PACKET_remaining(pkt), al) <= 0)
+        ENDPOINT role = (context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0
+                        ? ENDPOINT_CLIENT : ENDPOINT_BOTH;
+
+        /*
+         * If we didn't ask for it then there must be a custom extension,
+         * otherwise this is unsolicited.
+         */
+        if (custom_ext_find(&s->cert->custext, role,
+                            TLSEXT_TYPE_signed_certificate_timestamp,
+                            NULL) == NULL) {
+            SSLfatal(s, TLS1_AD_UNSUPPORTED_EXTENSION, SSL_F_TLS_PARSE_STOC_SCT,
+                     SSL_R_BAD_EXTENSION);
+            return 0;
+        }
+
+        if (!custom_ext_parse(s, context,
+                             TLSEXT_TYPE_signed_certificate_timestamp,
+                             PACKET_data(pkt), PACKET_remaining(pkt),
+                             x, chainidx)) {
+            /* SSLfatal already called */
             return 0;
+        }
     }
 
     return 1;
@@ -206,73 +1436,85 @@ int tls_parse_server_sct(SSL *s, PACKET *pkt, int *al)
  * elements of zero length are allowed and the set of elements must exactly
  * fill the length of the block. Returns 1 on success or 0 on failure.
  */
-static int ssl_next_proto_validate(PACKET *pkt)
+static int ssl_next_proto_validate(SSL *s, PACKET *pkt)
 {
     PACKET tmp_protocol;
 
     while (PACKET_remaining(pkt)) {
         if (!PACKET_get_length_prefixed_1(pkt, &tmp_protocol)
-            || PACKET_remaining(&tmp_protocol) == 0)
+            || PACKET_remaining(&tmp_protocol) == 0) {
+            SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL_NEXT_PROTO_VALIDATE,
+                     SSL_R_BAD_EXTENSION);
             return 0;
+        }
     }
 
     return 1;
 }
 
-int tls_parse_server_npn(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_npn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx)
 {
     unsigned char *selected;
     unsigned char selected_len;
     PACKET tmppkt;
 
-    if (s->s3->tmp.finish_md_len != 0)
+    /* Check if we are in a renegotiation. If so ignore this extension */
+    if (!SSL_IS_FIRST_HANDSHAKE(s))
         return 1;
 
     /* We must have requested it. */
-    if (s->ctx->next_proto_select_cb == NULL) {
-        *al = SSL_AD_UNSUPPORTED_EXTENSION;
+    if (s->ctx->ext.npn_select_cb == NULL) {
+        SSLfatal(s, SSL_AD_UNSUPPORTED_EXTENSION, SSL_F_TLS_PARSE_STOC_NPN,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
+
     /* The data must be valid */
     tmppkt = *pkt;
-    if (!ssl_next_proto_validate(&tmppkt)) {
-        *al = SSL_AD_DECODE_ERROR;
+    if (!ssl_next_proto_validate(s, &tmppkt)) {
+        /* SSLfatal() already called */
         return 0;
     }
-    if (s->ctx->next_proto_select_cb(s, &selected, &selected_len,
-                                     PACKET_data(pkt),
-                                     PACKET_remaining(pkt),
-                                     s->ctx->next_proto_select_cb_arg) !=
+    if (s->ctx->ext.npn_select_cb(s, &selected, &selected_len,
+                                  PACKET_data(pkt),
+                                  PACKET_remaining(pkt),
+                                  s->ctx->ext.npn_select_cb_arg) !=
              SSL_TLSEXT_ERR_OK) {
-        *al = SSL_AD_INTERNAL_ERROR;
+        SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_F_TLS_PARSE_STOC_NPN,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
+
     /*
      * Could be non-NULL if server has sent multiple NPN extensions in
      * a single Serverhello
      */
-    OPENSSL_free(s->next_proto_negotiated);
-    s->next_proto_negotiated = OPENSSL_malloc(selected_len);
-    if (s->next_proto_negotiated == NULL) {
-        *al = SSL_AD_INTERNAL_ERROR;
+    OPENSSL_free(s->ext.npn);
+    s->ext.npn = OPENSSL_malloc(selected_len);
+    if (s->ext.npn == NULL) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_NPN,
+                 ERR_R_INTERNAL_ERROR);
         return 0;
     }
 
-    memcpy(s->next_proto_negotiated, selected, selected_len);
-    s->next_proto_negotiated_len = selected_len;
-    s->s3->next_proto_neg_seen = 1;
+    memcpy(s->ext.npn, selected, selected_len);
+    s->ext.npn_len = selected_len;
+    s->s3->npn_seen = 1;
 
     return 1;
 }
 #endif
 
-int tls_parse_server_alpn(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                        size_t chainidx)
 {
     size_t len;
 
     /* We must have requested it. */
     if (!s->s3->alpn_sent) {
-        *al = SSL_AD_UNSUPPORTED_EXTENSION;
+        SSLfatal(s, SSL_AD_UNSUPPORTED_EXTENSION, SSL_F_TLS_PARSE_STOC_ALPN,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
     /*-
@@ -284,55 +1526,76 @@ int tls_parse_server_alpn(SSL *s, PACKET *pkt, int *al)
     if (!PACKET_get_net_2_len(pkt, &len)
         || PACKET_remaining(pkt) != len || !PACKET_get_1_len(pkt, &len)
         || PACKET_remaining(pkt) != len) {
-        *al = SSL_AD_DECODE_ERROR;
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_ALPN,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
     OPENSSL_free(s->s3->alpn_selected);
     s->s3->alpn_selected = OPENSSL_malloc(len);
     if (s->s3->alpn_selected == NULL) {
-        *al = SSL_AD_INTERNAL_ERROR;
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_ALPN,
+                 ERR_R_INTERNAL_ERROR);
         return 0;
     }
     if (!PACKET_copy_bytes(pkt, s->s3->alpn_selected, len)) {
-        *al = SSL_AD_DECODE_ERROR;
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_ALPN,
+                 SSL_R_BAD_EXTENSION);
         return 0;
     }
     s->s3->alpn_selected_len = len;
 
+    if (s->session->ext.alpn_selected == NULL
+            || s->session->ext.alpn_selected_len != len
+            || memcmp(s->session->ext.alpn_selected, s->s3->alpn_selected, len)
+               != 0) {
+        /* ALPN not consistent with the old session so cannot use early_data */
+        s->ext.early_data_ok = 0;
+    }
+    if (!s->hit) {
+        /* If a new session then update it with the selected ALPN */
+        s->session->ext.alpn_selected =
+            OPENSSL_memdup(s->s3->alpn_selected, s->s3->alpn_selected_len);
+        if (s->session->ext.alpn_selected == NULL) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_ALPN,
+                     ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+        s->session->ext.alpn_selected_len = s->s3->alpn_selected_len;
+    }
+
     return 1;
 }
 
 #ifndef OPENSSL_NO_SRTP
-int tls_parse_server_use_srtp(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_use_srtp(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                            size_t chainidx)
 {
     unsigned int id, ct, mki;
     int i;
     STACK_OF(SRTP_PROTECTION_PROFILE) *clnt;
     SRTP_PROTECTION_PROFILE *prof;
 
-    if (!PACKET_get_net_2(pkt, &ct)
-        || ct != 2 || !PACKET_get_net_2(pkt, &id)
-        || !PACKET_get_1(pkt, &mki)
-        || PACKET_remaining(pkt) != 0) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP,
-               SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-        *al = SSL_AD_DECODE_ERROR;
+    if (!PACKET_get_net_2(pkt, &ct) || ct != 2
+            || !PACKET_get_net_2(pkt, &id)
+            || !PACKET_get_1(pkt, &mki)
+            || PACKET_remaining(pkt) != 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_USE_SRTP,
+                 SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
         return 0;
     }
 
     if (mki != 0) {
         /* Must be no MKI, since we never offer one */
-        SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP, SSL_R_BAD_SRTP_MKI_VALUE);
-        *al = SSL_AD_ILLEGAL_PARAMETER;
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_USE_SRTP,
+                 SSL_R_BAD_SRTP_MKI_VALUE);
         return 0;
     }
 
-    clnt = SSL_get_srtp_profiles(s);
-
     /* Throw an error if the server gave us an unsolicited extension */
+    clnt = SSL_get_srtp_profiles(s);
     if (clnt == NULL) {
-        SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP, SSL_R_NO_SRTP_PROFILES);
-        *al = SSL_AD_DECODE_ERROR;
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_USE_SRTP,
+                 SSL_R_NO_SRTP_PROFILES);
         return 0;
     }
 
@@ -345,30 +1608,30 @@ int tls_parse_server_use_srtp(SSL *s, PACKET *pkt, int *al)
 
         if (prof->id == id) {
             s->srtp_profile = prof;
-            *al = 0;
             return 1;
         }
     }
 
-    SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP,
-           SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-    *al = SSL_AD_DECODE_ERROR;
+    SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_USE_SRTP,
+             SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
     return 0;
 }
 #endif
 
-int tls_parse_server_etm(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_etm(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx)
 {
     /* Ignore if inappropriate ciphersuite */
     if (!(s->options & SSL_OP_NO_ENCRYPT_THEN_MAC)
             && s->s3->tmp.new_cipher->algorithm_mac != SSL_AEAD
             && s->s3->tmp.new_cipher->algorithm_enc != SSL_RC4)
-        s->s3->flags |= TLS1_FLAGS_ENCRYPT_THEN_MAC;
+        s->ext.use_etm = 1;
 
     return 1;
 }
 
-int tls_parse_server_ems(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_ems(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx)
 {
     s->s3->flags |= TLS1_FLAGS_RECEIVED_EXTMS;
     if (!s->hit)
@@ -377,232 +1640,246 @@ int tls_parse_server_ems(SSL *s, PACKET *pkt, int *al)
     return 1;
 }
 
-int tls_parse_server_key_share(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_supported_versions(SSL *s, PACKET *pkt, unsigned int context,
+                                      X509 *x, size_t chainidx)
+{
+    unsigned int version;
+
+    if (!PACKET_get_net_2(pkt, &version)
+            || PACKET_remaining(pkt) != 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR,
+                 SSL_F_TLS_PARSE_STOC_SUPPORTED_VERSIONS,
+                 SSL_R_LENGTH_MISMATCH);
+        return 0;
+    }
+
+    /* TODO(TLS1.3): Remove this before release */
+    if (version == TLS1_3_VERSION_DRAFT)
+        version = TLS1_3_VERSION;
+
+    /* We ignore this extension for HRRs except to sanity check it */
+    if (context == SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST) {
+        /*
+         * The only protocol version we support which has an HRR message is
+         * TLSv1.3, therefore we shouldn't be getting an HRR for anything else.
+         */
+        if (version != TLS1_3_VERSION) {
+            *al = SSL_AD_PROTOCOL_VERSION;
+            SSLerr(SSL_F_TLS_PARSE_STOC_SUPPORTED_VERSIONS,
+                   SSL_R_BAD_HRR_VERSION);
+            return 0;
+        }
+        return 1;
+    }
+
+    /* We just set it here. We validate it in ssl_choose_client_version */
+    s->version = version;
+
+    return 1;
+}
+
+int tls_parse_stoc_key_share(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                             size_t chainidx)
 {
+#ifndef OPENSSL_NO_TLS1_3
     unsigned int group_id;
     PACKET encoded_pt;
     EVP_PKEY *ckey = s->s3->tmp.pkey, *skey = NULL;
 
     /* Sanity check */
-    if (ckey == NULL) {
-        *al = SSL_AD_INTERNAL_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+    if (ckey == NULL || s->s3->peer_tmp != NULL) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                 ERR_R_INTERNAL_ERROR);
         return 0;
     }
 
     if (!PACKET_get_net_2(pkt, &group_id)) {
-        *al = SSL_AD_HANDSHAKE_FAILURE;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_LENGTH_MISMATCH);
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                 SSL_R_LENGTH_MISMATCH);
         return 0;
     }
 
+    if ((context & SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST) != 0) {
+        const uint16_t *pgroups = NULL;
+        size_t i, num_groups;
+
+        if (PACKET_remaining(pkt) != 0) {
+            SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                     SSL_R_LENGTH_MISMATCH);
+            return 0;
+        }
+
+        /*
+         * It is an error if the HelloRetryRequest wants a key_share that we
+         * already sent in the first ClientHello
+         */
+        if (group_id == s->s3->group_id) {
+            SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
+                     SSL_F_TLS_PARSE_STOC_KEY_SHARE, SSL_R_BAD_KEY_SHARE);
+            return 0;
+        }
+
+        /* Validate the selected group is one we support */
+        tls1_get_supported_groups(s, &pgroups, &num_groups);
+        for (i = 0; i < num_groups; i++) {
+            if (group_id == pgroups[i])
+                break;
+        }
+        if (i >= num_groups
+                || !tls_curve_allowed(s, group_id, SSL_SECOP_CURVE_SUPPORTED)) {
+            SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
+                     SSL_F_TLS_PARSE_STOC_KEY_SHARE, SSL_R_BAD_KEY_SHARE);
+            return 0;
+        }
+
+        s->s3->group_id = group_id;
+        EVP_PKEY_free(s->s3->tmp.pkey);
+        s->s3->tmp.pkey = NULL;
+        return 1;
+    }
+
     if (group_id != s->s3->group_id) {
         /*
          * This isn't for the group that we sent in the original
          * key_share!
          */
-        *al = SSL_AD_HANDSHAKE_FAILURE;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_BAD_KEY_SHARE);
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                 SSL_R_BAD_KEY_SHARE);
         return 0;
     }
 
     if (!PACKET_as_length_prefixed_2(pkt, &encoded_pt)
             || PACKET_remaining(&encoded_pt) == 0) {
-        *al = SSL_AD_DECODE_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_LENGTH_MISMATCH);
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                 SSL_R_LENGTH_MISMATCH);
         return 0;
     }
 
     skey = ssl_generate_pkey(ckey);
     if (skey == NULL) {
-        *al = SSL_AD_INTERNAL_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, ERR_R_MALLOC_FAILURE);
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                 ERR_R_MALLOC_FAILURE);
         return 0;
     }
     if (!EVP_PKEY_set1_tls_encodedpoint(skey, PACKET_data(&encoded_pt),
                                         PACKET_remaining(&encoded_pt))) {
-        *al = SSL_AD_DECODE_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_BAD_ECPOINT);
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_KEY_SHARE,
+                 SSL_R_BAD_ECPOINT);
+        EVP_PKEY_free(skey);
         return 0;
     }
 
     if (ssl_derive(s, ckey, skey, 1) == 0) {
-        *al = SSL_AD_INTERNAL_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        /* SSLfatal() already called */
         EVP_PKEY_free(skey);
         return 0;
     }
-    EVP_PKEY_free(skey);
+    s->s3->peer_tmp = skey;
+#endif
 
     return 1;
 }
 
-static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
+int tls_parse_stoc_cookie(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx)
 {
-    size_t num_extensions = 0;
-    RAW_EXTENSION *extensions = NULL;
-    PACKET extpkt;
+    PACKET cookie;
 
-#ifndef OPENSSL_NO_NEXTPROTONEG
-    s->s3->next_proto_neg_seen = 0;
-#endif
-    s->tlsext_ticket_expected = 0;
-
-    OPENSSL_free(s->s3->alpn_selected);
-    s->s3->alpn_selected = NULL;
+    if (!PACKET_as_length_prefixed_2(pkt, &cookie)
+            || !PACKET_memdup(&cookie, &s->ext.tls13_cookie,
+                              &s->ext.tls13_cookie_len)) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_COOKIE,
+                 SSL_R_LENGTH_MISMATCH);
+        return 0;
+    }
 
-    s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
+    return 1;
+}
 
-    s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
+int tls_parse_stoc_early_data(SSL *s, PACKET *pkt, unsigned int context,
+                              X509 *x, size_t chainidx)
+{
+    if (context == SSL_EXT_TLS1_3_NEW_SESSION_TICKET) {
+        unsigned long max_early_data;
 
-    if (!PACKET_as_length_prefixed_2(pkt, &extpkt)) {
-        /* Extensions block may be completely absent in SSLv3 */
-        if (s->version != SSL3_VERSION || PACKET_remaining(pkt) != 0) {
-            *al = SSL_AD_DECODE_ERROR;
-            SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_BAD_LENGTH);
+        if (!PACKET_get_net_4(pkt, &max_early_data)
+                || PACKET_remaining(pkt) != 0) {
+            SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_EARLY_DATA,
+                     SSL_R_INVALID_MAX_EARLY_DATA);
             return 0;
         }
-        PACKET_null_init(&extpkt);
-    }
-
-    /*
-     * TODO(TLS1.3): We give multiple contexts for now until we're ready to
-     * give something more specific
-     */
 
-    if (!tls_collect_extensions(s, &extpkt, EXT_TLS1_2_SERVER_HELLO
-                                            | EXT_TLS1_3_SERVER_HELLO
-                                            | EXT_TLS1_3_ENCRYPTED_EXTENSIONS
-                                            | EXT_TLS1_3_CERTIFICATE,
-                                &extensions, &num_extensions, al))
-        return 0;
+        s->session->ext.max_early_data = max_early_data;
 
-    /*
-     * Determine if we need to see RI. Strictly speaking if we want to avoid
-     * an attack we should *always* see RI even on initial server hello
-     * because the client doesn't see any renegotiation during an attack.
-     * However this would mean we could not connect to any server which
-     * doesn't support RI so for the immediate future tolerate RI absence
-     */
-    if (!(s->options & SSL_OP_LEGACY_SERVER_CONNECT)
-            && !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)
-            && tls_get_extension_by_type(extensions, num_extensions,
-                                         TLSEXT_TYPE_renegotiate) == NULL) {
-        *al = SSL_AD_HANDSHAKE_FAILURE;
-        SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT,
-               SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
-        return 0;
+        return 1;
     }
 
-    if (!tls_parse_all_extensions(s, EXT_TLS1_2_SERVER_HELLO
-                                     | EXT_TLS1_3_SERVER_HELLO
-                                     | EXT_TLS1_3_ENCRYPTED_EXTENSIONS
-                                     | EXT_TLS1_3_CERTIFICATE,
-                                  extensions, num_extensions, al))
+    if (PACKET_remaining(pkt) != 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_EARLY_DATA,
+                 SSL_R_BAD_EXTENSION);
         return 0;
+    }
 
-    if (s->hit) {
+    if (!s->ext.early_data_ok
+            || !s->hit
+            || s->session->ext.tick_identity != 0) {
         /*
-         * Check extended master secret extension is consistent with
-         * original session.
+         * If we get here then we didn't send early data, or we didn't resume
+         * using the first identity, or the SNI/ALPN is not consistent so the
+         * server should not be accepting it.
          */
-        if (!(s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) !=
-            !(s->session->flags & SSL_SESS_FLAG_EXTMS)) {
-            *al = SSL_AD_HANDSHAKE_FAILURE;
-            SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_INCONSISTENT_EXTMS);
-            return 0;
-        }
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_EARLY_DATA,
+                 SSL_R_BAD_EXTENSION);
+        return 0;
     }
 
+    s->ext.early_data = SSL_EARLY_DATA_ACCEPTED;
+
     return 1;
 }
 
-static int ssl_check_serverhello_tlsext(SSL *s)
+int tls_parse_stoc_psk(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx)
 {
-    int ret = SSL_TLSEXT_ERR_NOACK;
-    int al = SSL_AD_UNRECOGNIZED_NAME;
+#ifndef OPENSSL_NO_TLS1_3
+    unsigned int identity;
 
-#ifndef OPENSSL_NO_EC
-    /*
-     * If we are client and using an elliptic curve cryptography cipher
-     * suite, then if server returns an EC point formats lists extension it
-     * must contain uncompressed.
-     */
-    unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
-    unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
-    if ((s->tlsext_ecpointformatlist != NULL)
-        && (s->tlsext_ecpointformatlist_length > 0)
-        && (s->session->tlsext_ecpointformatlist != NULL)
-        && (s->session->tlsext_ecpointformatlist_length > 0)
-        && ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))) {
-        /* we are using an ECC cipher */
-        size_t i;
-        unsigned char *list;
-        int found_uncompressed = 0;
-        list = s->session->tlsext_ecpointformatlist;
-        for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++) {
-            if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
-                found_uncompressed = 1;
-                break;
-            }
-        }
-        if (!found_uncompressed) {
-            SSLerr(SSL_F_SSL_CHECK_SERVERHELLO_TLSEXT,
-                   SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
-            return -1;
-        }
+    if (!PACKET_get_net_2(pkt, &identity) || PACKET_remaining(pkt) != 0) {
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_PARSE_STOC_PSK,
+                 SSL_R_LENGTH_MISMATCH);
+        return 0;
     }
-    ret = SSL_TLSEXT_ERR_OK;
-#endif                          /* OPENSSL_NO_EC */
-
-    if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
-        ret =
-            s->ctx->tlsext_servername_callback(s, &al,
-                                               s->ctx->tlsext_servername_arg);
-    else if (s->initial_ctx != NULL
-             && s->initial_ctx->tlsext_servername_callback != 0)
-        ret =
-            s->initial_ctx->tlsext_servername_callback(s, &al,
-                                                       s->
-                                                       initial_ctx->tlsext_servername_arg);
-
-    /*
-     * Ensure we get sensible values passed to tlsext_status_cb in the event
-     * that we don't receive a status message
-     */
-    OPENSSL_free(s->tlsext_ocsp_resp);
-    s->tlsext_ocsp_resp = NULL;
-    s->tlsext_ocsp_resplen = 0;
 
-    switch (ret) {
-    case SSL_TLSEXT_ERR_ALERT_FATAL:
-        ssl3_send_alert(s, SSL3_AL_FATAL, al);
-        return -1;
-
-    case SSL_TLSEXT_ERR_ALERT_WARNING:
-        ssl3_send_alert(s, SSL3_AL_WARNING, al);
-        return 1;
-
-    case SSL_TLSEXT_ERR_NOACK:
-        s->servername_done = 0;
-    default:
+    if (s->session->ext.tick_identity == (int)identity) {
+        s->hit = 1;
+        SSL_SESSION_free(s->psksession);
+        s->psksession = NULL;
         return 1;
     }
-}
 
-int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt)
-{
-    int al = -1;
-    if (s->version < SSL3_VERSION)
-        return 1;
-    if (ssl_scan_serverhello_tlsext(s, pkt, &al) <= 0) {
-        ssl3_send_alert(s, SSL3_AL_FATAL, al);
+    if (s->psksession == NULL
+            || s->psksession->ext.tick_identity != (int)identity) {
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PARSE_STOC_PSK,
+                 SSL_R_BAD_PSK_IDENTITY);
         return 0;
     }
 
-    if (ssl_check_serverhello_tlsext(s) <= 0) {
-        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT, SSL_R_SERVERHELLO_TLSEXT);
-        return 0;
-    }
+    /*
+     * If we used the external PSK for sending early_data then s->early_secret
+     * is already set up, so don't overwrite it. Otherwise we copy the
+     * early_secret across that we generated earlier.
+     */
+    if ((s->early_data_state != SSL_EARLY_DATA_WRITE_RETRY
+                && s->early_data_state != SSL_EARLY_DATA_FINISHED_WRITING)
+            || s->session->ext.max_early_data > 0
+            || s->psksession->ext.max_early_data == 0)
+        memcpy(s->early_secret, s->psksession->early_secret, EVP_MAX_MD_SIZE);
+
+    SSL_SESSION_free(s->session);
+    s->session = s->psksession;
+    s->psksession = NULL;
+    s->hit = 1;
+#endif
+
     return 1;
 }