Parse the early_data extension
[openssl.git] / ssl / statem / extensions_srvr.c
index 38a6bef8627dd1097840263dba43e5b02a0cd24a..8994ab9cc1b65cbb8037789da5285ec009d5d12d 100644 (file)
@@ -14,7 +14,8 @@
 /*
  * Parse the client's renegotiation binding and abort if it's not right
  */
-int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_renegotiate(SSL *s, PACKET *pkt, unsigned int context,
+                               X509 *x, size_t chainidx, int *al)
 {
     unsigned int ilen;
     const unsigned char *data;
@@ -22,7 +23,7 @@ int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
     /* Parse the length byte */
     if (!PACKET_get_1(pkt, &ilen)
         || !PACKET_get_bytes(pkt, &data, ilen)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
+        SSLerr(SSL_F_TLS_PARSE_CTOS_RENEGOTIATE,
                SSL_R_RENEGOTIATION_ENCODING_ERR);
         *al = SSL_AD_ILLEGAL_PARAMETER;
         return 0;
@@ -30,7 +31,7 @@ int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
 
     /* Check that the extension matches */
     if (ilen != s->s3->previous_client_finished_len) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
+        SSLerr(SSL_F_TLS_PARSE_CTOS_RENEGOTIATE,
                SSL_R_RENEGOTIATION_MISMATCH);
         *al = SSL_AD_HANDSHAKE_FAILURE;
         return 0;
@@ -38,7 +39,7 @@ int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
 
     if (memcmp(data, s->s3->previous_client_finished,
                s->s3->previous_client_finished_len)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
+        SSLerr(SSL_F_TLS_PARSE_CTOS_RENEGOTIATE,
                SSL_R_RENEGOTIATION_MISMATCH);
         *al = SSL_AD_HANDSHAKE_FAILURE;
         return 0;
@@ -49,35 +50,35 @@ int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
     return 1;
 }
 
-int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, int *al)
+/*-
+ * The servername extension is treated as follows:
+ *
+ * - Only the hostname type is supported with a maximum length of 255.
+ * - The servername is rejected if too long or if it contains zeros,
+ *   in which case an fatal alert is generated.
+ * - The servername field is maintained together with the session cache.
+ * - When a session is resumed, the servername call back invoked in order
+ *   to allow the application to position itself to the right context.
+ * - The servername is acknowledged if it is new for a session or when
+ *   it is identical to a previously used for the same session.
+ *   Applications can control the behaviour.  They can at any time
+ *   set a 'desirable' servername for a new SSL object. This can be the
+ *   case for example with HTTPS when a Host: header field is received and
+ *   a renegotiation is requested. In this case, a possible servername
+ *   presented in the new client hello is only acknowledged if it matches
+ *   the value of the Host: field.
+ * - Applications must  use SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
+ *   if they provide for changing an explicit servername context for the
+ *   session, i.e. when the session has been established with a servername
+ *   extension.
+ * - On session reconnect, the servername extension may be absent.
+ */
+int tls_parse_ctos_server_name(SSL *s, PACKET *pkt, unsigned int context,
+                               X509 *x, size_t chainidx, int *al)
 {
     unsigned int servname_type;
     PACKET sni, hostname;
 
-    /*-
-     * The servername extension is treated as follows:
-     *
-     * - Only the hostname type is supported with a maximum length of 255.
-     * - The servername is rejected if too long or if it contains zeros,
-     *   in which case an fatal alert is generated.
-     * - The servername field is maintained together with the session cache.
-     * - When a session is resumed, the servername call back invoked in order
-     *   to allow the application to position itself to the right context.
-     * - The servername is acknowledged if it is new for a session or when
-     *   it is identical to a previously used for the same session.
-     *   Applications can control the behaviour.  They can at any time
-     *   set a 'desirable' servername for a new SSL object. This can be the
-     *   case for example with HTTPS when a Host: header field is received and
-     *   a renegotiation is requested. In this case, a possible servername
-     *   presented in the new client hello is only acknowledged if it matches
-     *   the value of the Host: field.
-     * - Applications must  use SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
-     *   if they provide for changing an explicit servername context for the
-     *   session, i.e. when the session has been established with a servername
-     *   extension.
-     * - On session reconnect, the servername extension may be absent.
-     *
-     */
     if (!PACKET_as_length_prefixed_2(pkt, &sni)
         /* ServerNameList must be at least 1 byte long. */
         || PACKET_remaining(&sni) == 0) {
@@ -88,7 +89,7 @@ int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, int *al)
     /*
      * Although the server_name extension was intended to be
      * extensible to new name types, RFC 4366 defined the
-     * syntax inextensibility and OpenSSL 1.0.x parses it as
+     * syntax inextensibly and OpenSSL 1.0.x parses it as
      * such.
      * RFC 6066 corrected the mistake but adding new name types
      * is nevertheless no longer feasible, so act as if no other
@@ -115,7 +116,9 @@ int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, int *al)
             return 0;
         }
 
-        if (!PACKET_strndup(&hostname, &s->session->tlsext_hostname)) {
+        OPENSSL_free(s->session->ext.hostname);
+        s->session->ext.hostname = NULL;
+        if (!PACKET_strndup(&hostname, &s->session->ext.hostname)) {
             *al = TLS1_AD_INTERNAL_ERROR;
             return 0;
         }
@@ -126,16 +129,17 @@ int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, int *al)
          * TODO(openssl-team): if the SNI doesn't match, we MUST
          * fall back to a full handshake.
          */
-        s->servername_done = s->session->tlsext_hostname
-            && PACKET_equal(&hostname, s->session->tlsext_hostname,
-                            strlen(s->session->tlsext_hostname));
+        s->servername_done = s->session->ext.hostname
+            && PACKET_equal(&hostname, s->session->ext.hostname,
+                            strlen(s->session->ext.hostname));
     }
 
     return 1;
 }
 
 #ifndef OPENSSL_NO_SRP
-int tls_parse_clienthello_srp(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_srp(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx, int *al)
 {
     PACKET srp_I;
 
@@ -158,8 +162,22 @@ int tls_parse_clienthello_srp(SSL *s, PACKET *pkt, int *al)
 }
 #endif
 
+int tls_parse_ctos_early_data(SSL *s, PACKET *pkt, unsigned int context,
+                              X509 *x, size_t chainidx, int *al)
+{
+    if (PACKET_remaining(pkt) != 0) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    s->ext.expect_early_data = 1;
+
+    return 1;
+}
+
 #ifndef OPENSSL_NO_EC
-int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_ec_pt_formats(SSL *s, PACKET *pkt, unsigned int context,
+                                 X509 *x, size_t chainidx, int *al)
 {
     PACKET ec_point_format_list;
 
@@ -171,8 +189,8 @@ int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
 
     if (!s->hit) {
         if (!PACKET_memdup(&ec_point_format_list,
-                           &s->session->tlsext_ecpointformatlist,
-                           &s->session->tlsext_ecpointformatlist_length)) {
+                           &s->session->ext.ecpointformats,
+                           &s->session->ext.ecpointformats_len)) {
             *al = TLS1_AD_INTERNAL_ERROR;
             return 0;
         }
@@ -182,12 +200,13 @@ int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
 }
 #endif                          /* OPENSSL_NO_EC */
 
-int tls_parse_clienthello_session_ticket(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_session_ticket(SSL *s, PACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx, int *al)
 {
-    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)) {
+    if (s->ext.session_ticket_cb &&
+            !s->ext.session_ticket_cb(s, PACKET_data(pkt),
+                                  PACKET_remaining(pkt),
+                                  s->ext.session_ticket_cb_arg)) {
         *al = TLS1_AD_INTERNAL_ERROR;
         return 0;
     }
@@ -195,159 +214,150 @@ int tls_parse_clienthello_session_ticket(SSL *s, PACKET *pkt, int *al)
     return 1;
 }
 
-int tls_parse_clienthello_sig_algs(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_sig_algs(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                            size_t chainidx, int *al)
 {
     PACKET supported_sig_algs;
 
     if (!PACKET_as_length_prefixed_2(pkt, &supported_sig_algs)
-            || (PACKET_remaining(&supported_sig_algs) % 2) != 0
             || PACKET_remaining(&supported_sig_algs) == 0) {
         *al = SSL_AD_DECODE_ERROR;
         return 0;
     }
 
-    if (!s->hit && !tls1_save_sigalgs(s, PACKET_data(&supported_sig_algs),
-                                      PACKET_remaining(&supported_sig_algs))) {
-        *al = TLS1_AD_INTERNAL_ERROR;
+    if (!s->hit && !tls1_save_sigalgs(s, &supported_sig_algs)) {
+        *al = TLS1_AD_DECODE_ERROR;
         return 0;
     }
 
     return 1;
 }
 
-int tls_parse_clienthello_status_request(SSL *s, PACKET *pkt, int *al)
+#ifndef OPENSSL_NO_OCSP
+int tls_parse_ctos_status_request(SSL *s, PACKET *pkt, unsigned int context,
+                                  X509 *x, size_t chainidx, int *al)
 {
-    if (!PACKET_get_1(pkt, (unsigned int *)&s->tlsext_status_type)) {
+    PACKET responder_id_list, exts;
+
+    /* Not defined if we get one of these in a client Certificate */
+    if (x != NULL)
+        return 1;
+
+    if (!PACKET_get_1(pkt, (unsigned int *)&s->ext.status_type)) {
         *al = SSL_AD_DECODE_ERROR;
         return 0;
     }
-#ifndef OPENSSL_NO_OCSP
-    if (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp) {
-        const unsigned char *ext_data;
-        PACKET responder_id_list, exts;
-        if (!PACKET_get_length_prefixed_2 (pkt, &responder_id_list)) {
-            *al = SSL_AD_DECODE_ERROR;
-            return 0;
-        }
 
+    if (s->ext.status_type != TLSEXT_STATUSTYPE_ocsp) {
         /*
-         * We remove any OCSP_RESPIDs from a previous handshake
-         * to prevent unbounded memory growth - CVE-2016-6304
+         * We don't know what to do with any other type so ignore it.
          */
-        sk_OCSP_RESPID_pop_free(s->tlsext_ocsp_ids, OCSP_RESPID_free);
-        if (PACKET_remaining(&responder_id_list) > 0) {
-            s->tlsext_ocsp_ids = sk_OCSP_RESPID_new_null();
-            if (s->tlsext_ocsp_ids == NULL) {
-                *al = SSL_AD_INTERNAL_ERROR;
-                return 0;
-            }
-        } else {
-            s->tlsext_ocsp_ids = NULL;
-        }
+        s->ext.status_type = TLSEXT_STATUSTYPE_nothing;
+        return 1;
+    }
 
-        while (PACKET_remaining(&responder_id_list) > 0) {
-            OCSP_RESPID *id;
-            PACKET responder_id;
-            const unsigned char *id_data;
+    if (!PACKET_get_length_prefixed_2 (pkt, &responder_id_list)) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
 
-            if (!PACKET_get_length_prefixed_2(&responder_id_list,
-                                              &responder_id)
-                    || PACKET_remaining(&responder_id) == 0) {
-                *al = SSL_AD_DECODE_ERROR;
-                return 0;
-            }
+    /*
+     * We remove any OCSP_RESPIDs from a previous handshake
+     * to prevent unbounded memory growth - CVE-2016-6304
+     */
+    sk_OCSP_RESPID_pop_free(s->ext.ocsp.ids, OCSP_RESPID_free);
+    if (PACKET_remaining(&responder_id_list) > 0) {
+        s->ext.ocsp.ids = sk_OCSP_RESPID_new_null();
+        if (s->ext.ocsp.ids == NULL) {
+            *al = SSL_AD_INTERNAL_ERROR;
+            return 0;
+        }
+    } else {
+        s->ext.ocsp.ids = NULL;
+    }
 
-            id_data = PACKET_data(&responder_id);
-            /* TODO(size_t): Convert d2i_* to size_t */
-            id = d2i_OCSP_RESPID(NULL, &id_data,
-                                 (int)PACKET_remaining(&responder_id));
-            if (id == NULL) {
-                *al = SSL_AD_DECODE_ERROR;
-                return 0;
-            }
+    while (PACKET_remaining(&responder_id_list) > 0) {
+        OCSP_RESPID *id;
+        PACKET responder_id;
+        const unsigned char *id_data;
 
-            if (id_data != PACKET_end(&responder_id)) {
-                OCSP_RESPID_free(id);
-                *al = SSL_AD_DECODE_ERROR;
-                return 0;
-            }
+        if (!PACKET_get_length_prefixed_2(&responder_id_list, &responder_id)
+                || PACKET_remaining(&responder_id) == 0) {
+            *al = SSL_AD_DECODE_ERROR;
+            return 0;
+        }
 
-            if (!sk_OCSP_RESPID_push(s->tlsext_ocsp_ids, id)) {
-                OCSP_RESPID_free(id);
-                *al = SSL_AD_INTERNAL_ERROR;
-                return 0;
-            }
+        id_data = PACKET_data(&responder_id);
+        /* TODO(size_t): Convert d2i_* to size_t */
+        id = d2i_OCSP_RESPID(NULL, &id_data,
+                             (int)PACKET_remaining(&responder_id));
+        if (id == NULL) {
+            *al = SSL_AD_DECODE_ERROR;
+            return 0;
         }
 
-        /* Read in request_extensions */
-        if (!PACKET_as_length_prefixed_2(pkt, &exts)) {
+        if (id_data != PACKET_end(&responder_id)) {
+            OCSP_RESPID_free(id);
             *al = SSL_AD_DECODE_ERROR;
             return 0;
         }
 
-        if (PACKET_remaining(&exts) > 0) {
-            ext_data = PACKET_data(&exts);
-            sk_X509_EXTENSION_pop_free(s->tlsext_ocsp_exts,
-                                       X509_EXTENSION_free);
-            s->tlsext_ocsp_exts =
-                d2i_X509_EXTENSIONS(NULL, &ext_data,
-                                    (int)PACKET_remaining(&exts));
-            if (s->tlsext_ocsp_exts == NULL || ext_data != PACKET_end(&exts)) {
-                *al = SSL_AD_DECODE_ERROR;
-                return 0;
-            }
+        if (!sk_OCSP_RESPID_push(s->ext.ocsp.ids, id)) {
+            OCSP_RESPID_free(id);
+            *al = SSL_AD_INTERNAL_ERROR;
+            return 0;
+        }
+    }
+
+    /* Read in request_extensions */
+    if (!PACKET_as_length_prefixed_2(pkt, &exts)) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    if (PACKET_remaining(&exts) > 0) {
+        const unsigned char *ext_data = PACKET_data(&exts);
+
+        sk_X509_EXTENSION_pop_free(s->ext.ocsp.exts,
+                                   X509_EXTENSION_free);
+        s->ext.ocsp.exts =
+            d2i_X509_EXTENSIONS(NULL, &ext_data, (int)PACKET_remaining(&exts));
+        if (s->ext.ocsp.exts == NULL || ext_data != PACKET_end(&exts)) {
+            *al = SSL_AD_DECODE_ERROR;
+            return 0;
         }
-    } else
-#endif
-    {
-        /*
-         * We don't know what to do with any other type so ignore it.
-         */
-        s->tlsext_status_type = -1;
     }
 
     return 1;
 }
+#endif
 
 #ifndef OPENSSL_NO_NEXTPROTONEG
-int tls_parse_clienthello_npn(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_npn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx, int *al)
 {
-    if (s->s3->tmp.finish_md_len == 0) {
-        /*-
-         * We shouldn't accept this extension on a
-         * renegotiation.
-         *
-         * s->new_session will be set on renegotiation, but we
-         * probably shouldn't rely that it couldn't be set on
-         * the initial renegotiation too in certain cases (when
-         * there's some other reason to disallow resuming an
-         * earlier session -- the current code won't be doing
-         * anything like that, but this might change).
-         *
-         * A valid sign that there's been a previous handshake
-         * in this connection is if s->s3->tmp.finish_md_len >
-         * 0.  (We are talking about a check that will happen
-         * in the Hello protocol round, well before a new
-         * Finished message could have been computed.)
-         */
-        s->s3->next_proto_neg_seen = 1;
-    }
+    /*
+     * We shouldn't accept this extension on a
+     * renegotiation.
+     */
+    if (SSL_IS_FIRST_HANDSHAKE(s))
+        s->s3->npn_seen = 1;
 
     return 1;
 }
 #endif
 
 /*
- * Save the ALPN extension in a ClientHello.
- * pkt: the contents of the ALPN extension, not including type and length.
- * al: a pointer to the  alert value to send in the event of a failure.
- * returns: 1 on success, 0 on error.
+ * Save the ALPN extension in a ClientHello.|pkt| holds the contents of the ALPN
+ * extension, not including type and length. |al| is a pointer to the alert
+ * value to send in the event of a failure. Returns: 1 on success, 0 on error.
  */
-int tls_parse_clienthello_alpn(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                        size_t chainidx, int *al)
 {
     PACKET protocol_list, save_protocol_list, protocol;
 
-    if (s->s3->tmp.finish_md_len != 0)
+    if (!SSL_IS_FIRST_HANDSHAKE(s))
         return 1;
 
     if (!PACKET_as_length_prefixed_2(pkt, &protocol_list)
@@ -366,6 +376,9 @@ int tls_parse_clienthello_alpn(SSL *s, PACKET *pkt, int *al)
         }
     } while (PACKET_remaining(&protocol_list) != 0);
 
+    OPENSSL_free(s->s3->alpn_proposed);
+    s->s3->alpn_proposed = NULL;
+    s->s3->alpn_proposed_len = 0;
     if (!PACKET_memdup(&save_protocol_list,
                        &s->s3->alpn_proposed, &s->s3->alpn_proposed_len)) {
         *al = TLS1_AD_INTERNAL_ERROR;
@@ -376,9 +389,9 @@ int tls_parse_clienthello_alpn(SSL *s, PACKET *pkt, int *al)
 }
 
 #ifndef OPENSSL_NO_SRTP
-int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_use_srtp(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                            size_t chainidx, int *al)
 {
-    SRTP_PROTECTION_PROFILE *sprof;
     STACK_OF(SRTP_PROTECTION_PROFILE) *srvr;
     unsigned int ct, mki_len, id;
     int i, srtp_pref;
@@ -389,9 +402,9 @@ int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
         return 1;
 
     /* Pull off the length of the cipher suite list  and check it is even */
-    if (!PACKET_get_net_2(pkt, &ct)
-        || (ct & 1) != 0 || !PACKET_get_sub_packet(pkt, &subpkt, ct)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_USE_SRTP,
+    if (!PACKET_get_net_2(pkt, &ct) || (ct & 1) != 0
+            || !PACKET_get_sub_packet(pkt, &subpkt, ct)) {
+        SSLerr(SSL_F_TLS_PARSE_CTOS_USE_SRTP,
                SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
         *al = SSL_AD_DECODE_ERROR;
         return 0;
@@ -404,7 +417,7 @@ int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
 
     while (PACKET_remaining(&subpkt)) {
         if (!PACKET_get_net_2(&subpkt, &id)) {
-            SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_USE_SRTP,
+            SSLerr(SSL_F_TLS_PARSE_CTOS_USE_SRTP,
                    SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
             *al = SSL_AD_DECODE_ERROR;
             return 0;
@@ -417,7 +430,9 @@ int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
          * does nothing.
          */
         for (i = 0; i < srtp_pref; i++) {
-            sprof = sk_SRTP_PROTECTION_PROFILE_value(srvr, i);
+            SRTP_PROTECTION_PROFILE *sprof =
+                sk_SRTP_PROTECTION_PROFILE_value(srvr, i);
+
             if (sprof->id == id) {
                 s->srtp_profile = sprof;
                 srtp_pref = i;
@@ -426,11 +441,9 @@ int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
         }
     }
 
-    /*
-     * Now extract the MKI value as a sanity check, but discard it for now
-     */
+    /* Now extract the MKI value as a sanity check, but discard it for now */
     if (!PACKET_get_1(pkt, &mki_len)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_USE_SRTP,
+        SSLerr(SSL_F_TLS_PARSE_CTOS_USE_SRTP,
                SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
         *al = SSL_AD_DECODE_ERROR;
         return 0;
@@ -438,7 +451,7 @@ int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
 
     if (!PACKET_forward(pkt, mki_len)
         || PACKET_remaining(pkt)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_USE_SRTP, SSL_R_BAD_SRTP_MKI_VALUE);
+        SSLerr(SSL_F_TLS_PARSE_CTOS_USE_SRTP, SSL_R_BAD_SRTP_MKI_VALUE);
         *al = SSL_AD_DECODE_ERROR;
         return 0;
     }
@@ -447,41 +460,42 @@ int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
 }
 #endif
 
-int tls_parse_clienthello_etm(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_etm(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx, int *al)
 {
     if (!(s->options & SSL_OP_NO_ENCRYPT_THEN_MAC))
-        s->s3->flags |= TLS1_FLAGS_ENCRYPT_THEN_MAC;
+        s->ext.use_etm = 1;
 
     return 1;
 }
 
 /*
- * Checks a list of |groups| to determine if the |group_id| is in it. If it is
- * and |checkallow| is 1 then additionally check if the group is allowed to be
- * used. Returns 1 if the group is in the list (and allowed if |checkallow| is
- * 1) or 0 otherwise.
+ * Process a psk_kex_modes extension received in the ClientHello. |pkt| contains
+ * the raw PACKET data for the extension. Returns 1 on success or 0 on failure.
+ * If a failure occurs then |*al| is set to an appropriate alert value.
  */
-static int check_in_list(SSL *s, unsigned int group_id,
-                         const unsigned char *groups, size_t num_groups,
-                         int checkallow)
+int tls_parse_ctos_psk_kex_modes(SSL *s, PACKET *pkt, unsigned int context,
+                                 X509 *x, size_t chainidx, int *al)
 {
-    size_t i;
+#ifndef OPENSSL_NO_TLS1_3
+    PACKET psk_kex_modes;
+    unsigned int mode;
 
-    if (groups == NULL || num_groups == 0)
+    if (!PACKET_as_length_prefixed_1(pkt, &psk_kex_modes)
+            || PACKET_remaining(&psk_kex_modes) == 0) {
+        *al = SSL_AD_DECODE_ERROR;
         return 0;
+    }
 
-    for (i = 0; i < num_groups; i++, groups += 2) {
-        unsigned int share_id = (groups[0] << 8) | (groups[1]);
-
-        if (group_id == share_id
-                && (!checkallow || tls_curve_allowed(s, groups,
-                                                     SSL_SECOP_CURVE_CHECK))) {
-            break;
-        }
+    while (PACKET_get_1(&psk_kex_modes, &mode)) {
+        if (mode == TLSEXT_KEX_MODE_KE_DHE)
+            s->ext.psk_kex_mode |= TLSEXT_KEX_MODE_FLAG_KE_DHE;
+        else if (mode == TLSEXT_KEX_MODE_KE)
+            s->ext.psk_kex_mode |= TLSEXT_KEX_MODE_FLAG_KE;
     }
+#endif
 
-    /* If i == num_groups then not in the list */
-    return i < num_groups;
+    return 1;
 }
 
 /*
@@ -489,8 +503,10 @@ static int check_in_list(SSL *s, unsigned int group_id,
  * the raw PACKET data for the extension. Returns 1 on success or 0 on failure.
  * If a failure occurs then |*al| is set to an appropriate alert value.
  */
-int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_key_share(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                             size_t chainidx, int *al)
 {
+#ifndef OPENSSL_NO_TLS1_3
     unsigned int group_id;
     PACKET key_share_list, encoded_pt;
     const unsigned char *clntcurves, *srvrcurves;
@@ -498,33 +514,37 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
     int group_nid, found = 0;
     unsigned int curve_flags;
 
-    if (s->hit)
+    if (s->hit && (s->ext.psk_kex_mode & TLSEXT_KEX_MODE_FLAG_KE_DHE) == 0)
         return 1;
 
     /* Sanity check */
     if (s->s3->peer_tmp != NULL) {
         *al = SSL_AD_INTERNAL_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, ERR_R_INTERNAL_ERROR);
         return 0;
     }
 
     if (!PACKET_as_length_prefixed_2(pkt, &key_share_list)) {
         *al = SSL_AD_HANDSHAKE_FAILURE;
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, SSL_R_LENGTH_MISMATCH);
+        SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, SSL_R_LENGTH_MISMATCH);
         return 0;
     }
 
     /* Get our list of supported curves */
     if (!tls1_get_curvelist(s, 0, &srvrcurves, &srvr_num_curves)) {
         *al = SSL_AD_INTERNAL_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, ERR_R_INTERNAL_ERROR);
         return 0;
     }
 
-    /* Get the clients list of supported curves */
+    /*
+     * Get the clients list of supported curves.
+     * TODO(TLS1.3): We should validate that we actually received
+     * supported_groups!
+     */
     if (!tls1_get_curvelist(s, 1, &clntcurves, &clnt_num_curves)) {
         *al = SSL_AD_INTERNAL_ERROR;
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, ERR_R_INTERNAL_ERROR);
         return 0;
     }
 
@@ -533,7 +553,7 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
                 || !PACKET_get_length_prefixed_2(&key_share_list, &encoded_pt)
                 || PACKET_remaining(&encoded_pt) == 0) {
             *al = SSL_AD_HANDSHAKE_FAILURE;
-            SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE,
+            SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE,
                    SSL_R_LENGTH_MISMATCH);
             return 0;
         }
@@ -548,7 +568,7 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
         /* Check if this share is in supported_groups sent from client */
         if (!check_in_list(s, group_id, clntcurves, clnt_num_curves, 0)) {
             *al = SSL_AD_HANDSHAKE_FAILURE;
-            SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, SSL_R_BAD_KEY_SHARE);
+            SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, SSL_R_BAD_KEY_SHARE);
             return 0;
         }
 
@@ -562,7 +582,7 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
 
         if (group_nid == 0) {
             *al = SSL_AD_INTERNAL_ERROR;
-            SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE,
+            SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE,
                    SSL_R_UNABLE_TO_FIND_ECDH_PARAMETERS);
             return 0;
         }
@@ -573,7 +593,7 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
 
             if (key == NULL || !EVP_PKEY_set_type(key, group_nid)) {
                 *al = SSL_AD_INTERNAL_ERROR;
-                SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, ERR_R_EVP_LIB);
+                SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, ERR_R_EVP_LIB);
                 EVP_PKEY_free(key);
                 return 0;
             }
@@ -581,13 +601,14 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
         } else {
             /* Set up EVP_PKEY with named curve as parameters */
             EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL);
+
             if (pctx == NULL
                     || EVP_PKEY_paramgen_init(pctx) <= 0
                     || EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx,
                                                               group_nid) <= 0
                     || EVP_PKEY_paramgen(pctx, &s->s3->peer_tmp) <= 0) {
                 *al = SSL_AD_INTERNAL_ERROR;
-                SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, ERR_R_EVP_LIB);
+                SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, ERR_R_EVP_LIB);
                 EVP_PKEY_CTX_free(pctx);
                 return 0;
             }
@@ -600,18 +621,20 @@ int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al)
                 PACKET_data(&encoded_pt),
                 PACKET_remaining(&encoded_pt))) {
             *al = SSL_AD_DECODE_ERROR;
-            SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_KEY_SHARE, SSL_R_BAD_ECPOINT);
+            SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, SSL_R_BAD_ECPOINT);
             return 0;
         }
 
         found = 1;
     }
+#endif
 
     return 1;
 }
 
 #ifndef OPENSSL_NO_EC
-int tls_parse_clienthello_supported_groups(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_supported_groups(SSL *s, PACKET *pkt, unsigned int context,
+                                    X509 *x, size_t chainidx, int *al)
 {
     PACKET supported_groups_list;
 
@@ -623,10 +646,12 @@ int tls_parse_clienthello_supported_groups(SSL *s, PACKET *pkt, int *al)
         return 0;
     }
 
-    if (!s->hit
-            && !PACKET_memdup(&supported_groups_list,
-                              &s->session->tlsext_supportedgroupslist,
-                              &s->session->tlsext_supportedgroupslist_length)) {
+    OPENSSL_free(s->session->ext.supportedgroups);
+    s->session->ext.supportedgroups = NULL;
+    s->session->ext.supportedgroups_len = 0;
+    if (!PACKET_memdup(&supported_groups_list,
+                       &s->session->ext.supportedgroups,
+                       &s->session->ext.supportedgroups_len)) {
         *al = SSL_AD_DECODE_ERROR;
         return 0;
     }
@@ -635,7 +660,8 @@ int tls_parse_clienthello_supported_groups(SSL *s, PACKET *pkt, int *al)
 }
 #endif
 
-int tls_parse_clienthello_ems(SSL *s, PACKET *pkt, int *al)
+int tls_parse_ctos_ems(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx, int *al)
 {
     /* The extension must always be empty */
     if (PACKET_remaining(pkt) != 0) {
@@ -647,3 +673,467 @@ int tls_parse_clienthello_ems(SSL *s, PACKET *pkt, int *al)
 
     return 1;
 }
+
+int tls_parse_ctos_psk(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
+                       size_t chainidx, int *al)
+{
+    PACKET identities, binders, binder;
+    size_t binderoffset, hashsize;
+    SSL_SESSION *sess = NULL;
+    unsigned int id, i;
+    const EVP_MD *md = NULL;
+
+    /*
+     * If we have no PSK kex mode that we recognise then we can't resume so
+     * ignore this extension
+     */
+    if ((s->ext.psk_kex_mode
+            & (TLSEXT_KEX_MODE_FLAG_KE | TLSEXT_KEX_MODE_FLAG_KE_DHE)) == 0)
+        return 1;
+
+    if (!PACKET_get_length_prefixed_2(pkt, &identities)) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    for (id = 0; PACKET_remaining(&identities) != 0; id++) {
+        PACKET identity;
+        unsigned long ticket_age;
+        int ret;
+
+        if (!PACKET_get_length_prefixed_2(&identities, &identity)
+                || !PACKET_get_net_4(&identities, &ticket_age)) {
+            *al = SSL_AD_DECODE_ERROR;
+            return 0;
+        }
+
+        /* TODO(TLS1.3): Should we validate the ticket age? */
+
+        ret = tls_decrypt_ticket(s, PACKET_data(&identity),
+                                 PACKET_remaining(&identity), NULL, 0, &sess);
+        if (ret == TICKET_FATAL_ERR_MALLOC || ret == TICKET_FATAL_ERR_OTHER) {
+            *al = SSL_AD_INTERNAL_ERROR;
+            return 0;
+        }
+        if (ret == TICKET_NO_DECRYPT)
+            continue;
+
+        md = ssl_md(sess->cipher->algorithm2);
+        if (md == NULL) {
+            /*
+             * Don't recognise this cipher so we can't use the session.
+             * Ignore it
+             */
+            SSL_SESSION_free(sess);
+            sess = NULL;
+            continue;
+        }
+
+        /*
+         * TODO(TLS1.3): Somehow we need to handle the case of a ticket renewal.
+         * Ignored for now
+         */
+
+        break;
+    }
+
+    if (sess == NULL)
+        return 1;
+
+    binderoffset = PACKET_data(pkt) - (const unsigned char *)s->init_buf->data;
+    hashsize = EVP_MD_size(md);
+
+    if (!PACKET_get_length_prefixed_2(pkt, &binders)) {
+        *al = SSL_AD_DECODE_ERROR;
+        goto err;
+    }
+
+    for (i = 0; i <= id; i++) {
+        if (!PACKET_get_length_prefixed_1(&binders, &binder)) {
+            *al = SSL_AD_DECODE_ERROR;
+            goto err;
+        }
+    }
+
+    if (PACKET_remaining(&binder) != hashsize
+            || tls_psk_do_binder(s, md,
+                                 (const unsigned char *)s->init_buf->data,
+                                 binderoffset, PACKET_data(&binder), NULL,
+                                 sess, 0) != 1) {
+        *al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_TLS_PARSE_CTOS_PSK, ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
+
+    sess->ext.tick_identity = id;
+    SSL_SESSION_free(s->session);
+    s->session = sess;
+    return 1;
+err:
+    return 0;
+}
+
+/*
+ * Add the server's renegotiation binding
+ */
+int tls_construct_stoc_renegotiate(SSL *s, WPACKET *pkt, unsigned int context,
+                                   X509 *x, size_t chainidx, int *al)
+{
+    if (!s->s3->send_connection_binding)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_renegotiate)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u8(pkt)
+            || !WPACKET_memcpy(pkt, s->s3->previous_client_finished,
+                               s->s3->previous_client_finished_len)
+            || !WPACKET_memcpy(pkt, s->s3->previous_server_finished,
+                               s->s3->previous_server_finished_len)
+            || !WPACKET_close(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_RENEGOTIATE, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_construct_stoc_server_name(SSL *s, WPACKET *pkt, unsigned int context,
+                                   X509 *x, size_t chainidx, int *al)
+{
+    if (s->hit || s->servername_done != 1
+            || s->session->ext.hostname == NULL)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_server_name)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_SERVER_NAME, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_construct_stoc_early_data_info(SSL *s, WPACKET *pkt,
+                                       unsigned int context, X509 *x,
+                                       size_t chainidx, int *al)
+{
+    if (s->max_early_data == 0)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_early_data_info)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u32(pkt, s->max_early_data)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_EARLY_DATA_INFO, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+#ifndef OPENSSL_NO_EC
+int tls_construct_stoc_ec_pt_formats(SSL *s, WPACKET *pkt, unsigned int context,
+                                     X509 *x, size_t chainidx, int *al)
+{
+    unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
+    unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
+    int using_ecc = ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))
+                    && (s->session->ext.ecpointformats != NULL);
+    const unsigned char *plist;
+    size_t plistlen;
+
+    if (!using_ecc)
+        return 1;
+
+    tls1_get_formatlist(s, &plist, &plistlen);
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_ec_point_formats)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_sub_memcpy_u8(pkt, plist, plistlen)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_EC_PT_FORMATS, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+#endif
+
+int tls_construct_stoc_session_ticket(SSL *s, WPACKET *pkt,
+                                      unsigned int context, X509 *x,
+                                      size_t chainidx, int *al)
+{
+    if (!s->ext.ticket_expected || !tls_use_ticket(s)) {
+        s->ext.ticket_expected = 0;
+        return 1;
+    }
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_session_ticket)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_SESSION_TICKET, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+#ifndef OPENSSL_NO_OCSP
+int tls_construct_stoc_status_request(SSL *s, WPACKET *pkt,
+                                      unsigned int context, X509 *x,
+                                      size_t chainidx, int *al)
+{
+    if (!s->ext.status_expected)
+        return 1;
+
+    if (SSL_IS_TLS13(s) && chainidx != 0)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_status_request)
+            || !WPACKET_start_sub_packet_u16(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_STATUS_REQUEST, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    /*
+     * In TLSv1.3 we include the certificate status itself. In <= TLSv1.2 we
+     * send back an empty extension, with the certificate status appearing as a
+     * separate message
+     */
+    if ((SSL_IS_TLS13(s) && !tls_construct_cert_status_body(s, pkt))
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_STATUS_REQUEST, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+#endif
+
+#ifndef OPENSSL_NO_NEXTPROTONEG
+int tls_construct_stoc_next_proto_neg(SSL *s, WPACKET *pkt,
+                                      unsigned int context, X509 *x,
+                                      size_t chainidx, int *al)
+{
+    const unsigned char *npa;
+    unsigned int npalen;
+    int ret;
+    int npn_seen = s->s3->npn_seen;
+
+    s->s3->npn_seen = 0;
+    if (!npn_seen || s->ctx->ext.npn_advertised_cb == NULL)
+        return 1;
+
+    ret = s->ctx->ext.npn_advertised_cb(s, &npa, &npalen,
+                                        s->ctx->ext.npn_advertised_cb_arg);
+    if (ret == SSL_TLSEXT_ERR_OK) {
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_next_proto_neg)
+                || !WPACKET_sub_memcpy_u16(pkt, npa, npalen)) {
+            SSLerr(SSL_F_TLS_CONSTRUCT_STOC_NEXT_PROTO_NEG,
+                   ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+        s->s3->npn_seen = 1;
+    }
+
+    return 1;
+}
+#endif
+
+int tls_construct_stoc_alpn(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
+                            size_t chainidx, int *al)
+{
+    if (s->s3->alpn_selected == NULL)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt,
+                TLSEXT_TYPE_application_layer_protocol_negotiation)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_sub_memcpy_u8(pkt, s->s3->alpn_selected,
+                                      s->s3->alpn_selected_len)
+            || !WPACKET_close(pkt)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_ALPN, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+#ifndef OPENSSL_NO_SRTP
+int tls_construct_stoc_use_srtp(SSL *s, WPACKET *pkt, unsigned int context,
+                                X509 *x, size_t chainidx, int *al)
+{
+    if (s->srtp_profile == NULL)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_use_srtp)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u16(pkt, 2)
+            || !WPACKET_put_bytes_u16(pkt, s->srtp_profile->id)
+            || !WPACKET_put_bytes_u8(pkt, 0)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_USE_SRTP, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+#endif
+
+int tls_construct_stoc_etm(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
+                           size_t chainidx, int *al)
+{
+    if (!s->ext.use_etm)
+        return 1;
+
+    /*
+     * Don't use encrypt_then_mac if AEAD or RC4 might want to disable
+     * for other cases too.
+     */
+    if (s->s3->tmp.new_cipher->algorithm_mac == SSL_AEAD
+        || s->s3->tmp.new_cipher->algorithm_enc == SSL_RC4
+        || s->s3->tmp.new_cipher->algorithm_enc == SSL_eGOST2814789CNT
+        || s->s3->tmp.new_cipher->algorithm_enc == SSL_eGOST2814789CNT12) {
+        s->ext.use_etm = 0;
+        return 1;
+    }
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_encrypt_then_mac)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_ETM, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_construct_stoc_ems(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
+                           size_t chainidx, int *al)
+{
+    if ((s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) == 0)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_extended_master_secret)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_EMS, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_construct_stoc_key_share(SSL *s, WPACKET *pkt, unsigned int context,
+                                 X509 *x, size_t chainidx, int *al)
+{
+#ifndef OPENSSL_NO_TLS1_3
+    unsigned char *encodedPoint;
+    size_t encoded_pt_len = 0;
+    EVP_PKEY *ckey = s->s3->peer_tmp, *skey = NULL;
+
+    if (ckey == NULL) {
+        /* No key_share received from client */
+        if (s->hello_retry_request) {
+            if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_key_share)
+                    || !WPACKET_start_sub_packet_u16(pkt)
+                    || !WPACKET_put_bytes_u16(pkt, s->s3->group_id)
+                    || !WPACKET_close(pkt)) {
+                SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE,
+                       ERR_R_INTERNAL_ERROR);
+                return 0;
+            }
+
+            return 1;
+        }
+
+        /* Must be resuming. */
+        if (!s->hit || !tls13_generate_handshake_secret(s, NULL, 0)) {
+            *al = SSL_AD_INTERNAL_ERROR;
+            SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+        return 1;
+    }
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_key_share)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u16(pkt, s->s3->group_id)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    skey = ssl_generate_pkey(ckey);
+    if (skey == NULL) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+
+    /* Generate encoding of server key */
+    encoded_pt_len = EVP_PKEY_get1_tls_encodedpoint(skey, &encodedPoint);
+    if (encoded_pt_len == 0) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE, ERR_R_EC_LIB);
+        EVP_PKEY_free(skey);
+        return 0;
+    }
+
+    if (!WPACKET_sub_memcpy_u16(pkt, encodedPoint, encoded_pt_len)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        EVP_PKEY_free(skey);
+        OPENSSL_free(encodedPoint);
+        return 0;
+    }
+    OPENSSL_free(encodedPoint);
+
+    /* This causes the crypto state to be updated based on the derived keys */
+    s->s3->tmp.pkey = skey;
+    if (ssl_derive(s, skey, ckey, 1) == 0) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_KEY_SHARE, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+#endif
+
+    return 1;
+}
+
+int tls_construct_stoc_cryptopro_bug(SSL *s, WPACKET *pkt, unsigned int context,
+                                     X509 *x, size_t chainidx, int *al)
+{
+    const unsigned char cryptopro_ext[36] = {
+        0xfd, 0xe8,         /* 65000 */
+        0x00, 0x20,         /* 32 bytes length */
+        0x30, 0x1e, 0x30, 0x08, 0x06, 0x06, 0x2a, 0x85,
+        0x03, 0x02, 0x02, 0x09, 0x30, 0x08, 0x06, 0x06,
+        0x2a, 0x85, 0x03, 0x02, 0x02, 0x16, 0x30, 0x08,
+        0x06, 0x06, 0x2a, 0x85, 0x03, 0x02, 0x02, 0x17
+    };
+
+    if (((s->s3->tmp.new_cipher->id & 0xFFFF) != 0x80
+         && (s->s3->tmp.new_cipher->id & 0xFFFF) != 0x81)
+            || (SSL_get_options(s) & SSL_OP_CRYPTOPRO_TLSEXT_BUG) == 0)
+        return 1;
+
+    if (!WPACKET_memcpy(pkt, cryptopro_ext, sizeof(cryptopro_ext))) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_CRYPTOPRO_BUG, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_construct_stoc_psk(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
+                           size_t chainidx, int *al)
+{
+    if (!s->hit)
+        return 1;
+
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_psk)
+            || !WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_put_bytes_u16(pkt, s->session->ext.tick_identity)
+            || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_STOC_PSK, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}