Fix some style issues identified during review
[openssl.git] / ssl / t1_lib.c
index 696998fe5eab030382a435f4a17713b126e14c32..3e592beb6c389ae68d0f1a5c06fc8a5c5bff5de5 100644 (file)
@@ -20,8 +20,8 @@
 #include "ssl_locl.h"
 #include <openssl/ct.h>
 
-static int tls_decrypt_ticket(SSL *s, const unsigned char *tick, int ticklen,
-                              const unsigned char *sess_id, int sesslen,
+static int tls_decrypt_ticket(SSL *s, const unsigned char *tick, size_t ticklen,
+                              const unsigned char *sess_id, size_t sesslen,
                               SSL_SESSION **psess);
 static int ssl_check_clienthello_tlsext_early(SSL *s);
 static int ssl_check_serverhello_tlsext(SSL *s);
@@ -33,15 +33,12 @@ SSL3_ENC_METHOD const TLSv1_enc_data = {
     tls1_generate_master_secret,
     tls1_change_cipher_state,
     tls1_final_finish_mac,
-    TLS1_FINISH_MAC_LENGTH,
     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
     tls1_alert_code,
     tls1_export_keying_material,
     0,
-    SSL3_HM_HEADER_LENGTH,
     ssl3_set_handshake_header,
-    ssl3_set_handshake_header2,
     tls_close_construct_packet,
     ssl3_handshake_write
 };
@@ -53,15 +50,12 @@ SSL3_ENC_METHOD const TLSv1_1_enc_data = {
     tls1_generate_master_secret,
     tls1_change_cipher_state,
     tls1_final_finish_mac,
-    TLS1_FINISH_MAC_LENGTH,
     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
     tls1_alert_code,
     tls1_export_keying_material,
     SSL_ENC_FLAG_EXPLICIT_IV,
-    SSL3_HM_HEADER_LENGTH,
     ssl3_set_handshake_header,
-    ssl3_set_handshake_header2,
     tls_close_construct_packet,
     ssl3_handshake_write
 };
@@ -73,16 +67,31 @@ SSL3_ENC_METHOD const TLSv1_2_enc_data = {
     tls1_generate_master_secret,
     tls1_change_cipher_state,
     tls1_final_finish_mac,
-    TLS1_FINISH_MAC_LENGTH,
     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
     tls1_alert_code,
     tls1_export_keying_material,
     SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS | SSL_ENC_FLAG_SHA256_PRF
         | SSL_ENC_FLAG_TLS1_2_CIPHERS,
-    SSL3_HM_HEADER_LENGTH,
     ssl3_set_handshake_header,
-    ssl3_set_handshake_header2,
+    tls_close_construct_packet,
+    ssl3_handshake_write
+};
+
+SSL3_ENC_METHOD const TLSv1_3_enc_data = {
+    tls1_enc,
+    tls1_mac,
+    tls13_setup_key_block,
+    tls13_generate_master_secret,
+    tls13_change_cipher_state,
+    tls13_final_finish_mac,
+    TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
+    TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
+    tls1_alert_code,
+    tls1_export_keying_material,
+    SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS | SSL_ENC_FLAG_SHA256_PRF
+        | SSL_ENC_FLAG_TLS1_2_CIPHERS,
+    ssl3_set_handshake_header,
     tls_close_construct_packet,
     ssl3_handshake_write
 };
@@ -237,7 +246,7 @@ int tls1_ec_nid2curve_id(int nid)
     size_t i;
     for (i = 0; i < OSSL_NELEM(nid_list); i++) {
         if (nid_list[i].nid == nid)
-            return i + 1;
+            return (int)(i + 1);
     }
     return 0;
 }
@@ -259,8 +268,8 @@ static int tls1_get_curvelist(SSL *s, int sess,
 {
     size_t pcurveslen = 0;
     if (sess) {
-        *pcurves = s->session->tlsext_ellipticcurvelist;
-        pcurveslen = s->session->tlsext_ellipticcurvelist_length;
+        *pcurves = s->session->tlsext_supportedgroupslist;
+        pcurveslen = s->session->tlsext_supportedgroupslist_length;
     } else {
         /* For Suite B mode only include P-256, P-384 */
         switch (tls1_suiteb(s)) {
@@ -279,8 +288,8 @@ static int tls1_get_curvelist(SSL *s, int sess,
             pcurveslen = 2;
             break;
         default:
-            *pcurves = s->tlsext_ellipticcurvelist;
-            pcurveslen = s->tlsext_ellipticcurvelist_length;
+            *pcurves = s->tlsext_supportedgroupslist;
+            pcurveslen = s->tlsext_supportedgroupslist_length;
         }
         if (!*pcurves) {
             *pcurves = eccurves_default;
@@ -347,13 +356,13 @@ int tls1_check_curve(SSL *s, const unsigned char *p, size_t len)
 }
 
 /*-
- * For nmatch >= 0, return the NID of the |nmatch|th shared curve or NID_undef
+ * For nmatch >= 0, return the NID of the |nmatch|th shared group or NID_undef
  * if there is no match.
  * For nmatch == -1, return number of matches
- * For nmatch == -2, return the NID of the curve to use for
+ * For nmatch == -2, return the NID of the group to use for
  * an EC tmp key, or NID_undef if there is no match.
  */
-int tls1_shared_curve(SSL *s, int nmatch)
+int tls1_shared_group(SSL *s, int nmatch)
 {
     const unsigned char *pref, *supp;
     size_t num_pref, num_supp, i, j;
@@ -425,34 +434,35 @@ int tls1_shared_curve(SSL *s, int nmatch)
     return NID_undef;
 }
 
-int tls1_set_curves(unsigned char **pext, size_t *pextlen,
-                    int *curves, size_t ncurves)
+int tls1_set_groups(unsigned char **pext, size_t *pextlen,
+                    int *groups, size_t ngroups)
 {
-    unsigned char *clist, *p;
+    unsigned char *glist, *p;
     size_t i;
     /*
-     * Bitmap of curves included to detect duplicates: only works while curve
+     * Bitmap of groups included to detect duplicates: only works while group
      * ids < 32
      */
     unsigned long dup_list = 0;
-    clist = OPENSSL_malloc(ncurves * 2);
-    if (clist == NULL)
+    glist = OPENSSL_malloc(ngroups * 2);
+    if (glist == NULL)
         return 0;
-    for (i = 0, p = clist; i < ncurves; i++) {
+    for (i = 0, p = glist; i < ngroups; i++) {
         unsigned long idmask;
         int id;
-        id = tls1_ec_nid2curve_id(curves[i]);
+        /* TODO(TLS1.3): Convert for DH groups */
+        id = tls1_ec_nid2curve_id(groups[i]);
         idmask = 1L << id;
         if (!id || (dup_list & idmask)) {
-            OPENSSL_free(clist);
+            OPENSSL_free(glist);
             return 0;
         }
         dup_list |= idmask;
         s2n(id, p);
     }
     OPENSSL_free(*pext);
-    *pext = clist;
-    *pextlen = ncurves * 2;
+    *pext = glist;
+    *pextlen = ngroups * 2;
     return 1;
 }
 
@@ -491,8 +501,8 @@ static int nid_cb(const char *elem, int len, void *arg)
     return 1;
 }
 
-/* Set curves based on a colon separate list */
-int tls1_set_curves_list(unsigned char **pext, size_t *pextlen, const char *str)
+/* Set groups based on a colon separate list */
+int tls1_set_groups_list(unsigned char **pext, size_t *pextlen, const char *str)
 {
     nid_cb_st ncb;
     ncb.nidcnt = 0;
@@ -500,7 +510,7 @@ int tls1_set_curves_list(unsigned char **pext, size_t *pextlen, const char *str)
         return 0;
     if (pext == NULL)
         return 1;
-    return tls1_set_curves(pext, pextlen, ncb.nid_arr, ncb.nidcnt);
+    return tls1_set_groups(pext, pextlen, ncb.nid_arr, ncb.nidcnt);
 }
 
 /* For an EC key set TLS id and required compression based on parameters */
@@ -697,7 +707,7 @@ int tls1_check_ec_tmp_key(SSL *s, unsigned long cid)
         return 1;
     }
     /* Need a shared curve */
-    if (tls1_shared_curve(s, 0))
+    if (tls1_shared_group(s, 0))
         return 1;
     return 0;
 }
@@ -933,7 +943,7 @@ int ssl_cipher_disabled(SSL *s, const SSL_CIPHER *c, int op)
 
 static int tls_use_ticket(SSL *s)
 {
-    if (s->options & SSL_OP_NO_TICKET)
+    if ((s->options & SSL_OP_NO_TICKET) || SSL_IS_TLS13(s))
         return 0;
     return ssl_security(s, SSL_SECOP_TICKET, 0, 0, NULL);
 }
@@ -1016,9 +1026,14 @@ static int tls1_check_duplicate_extensions(const PACKET *packet)
 int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
 {
 #ifndef OPENSSL_NO_EC
-    /* See if we support any ECC ciphersuites */
+    const unsigned char *pcurves = NULL;
+    size_t num_curves = 0;
     int using_ecc = 0;
-    if (s->version >= TLS1_VERSION || SSL_IS_DTLS(s)) {
+    int min_version, max_version, reason;
+
+    /* See if we support any ECC ciphersuites */
+    if ((s->version >= TLS1_VERSION && s->version <= TLS1_3_VERSION)
+            || SSL_IS_DTLS(s)) {
         int i;
         unsigned long alg_k, alg_a;
         STACK_OF(SSL_CIPHER) *cipher_stack = SSL_get_ciphers(s);
@@ -1029,19 +1044,28 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
             alg_k = c->algorithm_mkey;
             alg_a = c->algorithm_auth;
             if ((alg_k & (SSL_kECDHE | SSL_kECDHEPSK))
-                || (alg_a & SSL_aECDSA)) {
+                || (alg_a & SSL_aECDSA)
+                || c->min_tls >= TLS1_3_VERSION) {
                 using_ecc = 1;
                 break;
             }
         }
     }
+#else
+    if (SSL_IS_TLS13(s)) {
+        /* Shouldn't happen! */
+        SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
 #endif
 
     /* Add RI if renegotiating */
     if (s->renegotiate) {
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_renegotiate, 2)
-                || !WPACKET_sub_memcpy_u16(pkt, s->s3->previous_client_finished,
-                                   s->s3->previous_client_finished_len)) {
+        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)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
             return 0;
         }
@@ -1052,12 +1076,12 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
 
     if (s->tlsext_hostname != NULL) {
         /* Add TLS extension servername to the Client Hello message */
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_server_name, 2)
+        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(pkt, TLSEXT_NAMETYPE_host_name, 1)
+                || !WPACKET_put_bytes_u8(pkt, TLSEXT_NAMETYPE_host_name)
                 || !WPACKET_sub_memcpy_u16(pkt, s->tlsext_hostname,
                                            strlen(s->tlsext_hostname))
                 || !WPACKET_close(pkt)
@@ -1069,7 +1093,7 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
 #ifndef OPENSSL_NO_SRP
     /* Add SRP username if there is one */
     if (s->srp_ctx.login != NULL) {
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_srp, 2)
+        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)
@@ -1090,13 +1114,13 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
         /*
          * Add TLS extension ECPointFormats to the ClientHello message
          */
-        const unsigned char *pcurves, *pformats;
-        size_t num_curves, num_formats;
+        const unsigned char *pformats, *pcurvestmp;
+        size_t num_formats;
         size_t i;
 
         tls1_get_formatlist(s, &pformats, &num_formats);
 
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_ec_point_formats, 2)
+        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)
@@ -1106,26 +1130,28 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
         }
 
         /*
-         * Add TLS extension EllipticCurves to the ClientHello message
+         * Add TLS extension supported_groups to the ClientHello message
          */
-        pcurves = s->tlsext_ellipticcurvelist;
+        /* TODO(TLS1.3): Add support for DHE groups */
+        pcurves = s->tlsext_supportedgroupslist;
         if (!tls1_get_curvelist(s, 0, &pcurves, &num_curves)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
             return 0;
         }
+        pcurvestmp = pcurves;
 
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_elliptic_curves, 2)
-                   /* Sub-packet for curves extension */
+        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)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
             return 0;
         }
         /* Copy curve ID if supported */
-        for (i = 0; i < num_curves; i++, pcurves += 2) {
+        for (i = 0; i < num_curves; i++, pcurvestmp += 2) {
             if (tls_curve_allowed(s, pcurves, SSL_SECOP_CURVE_SUPPORTED)) {
-                if (!WPACKET_put_bytes(pkt, pcurves[0], 1)
-                    || !WPACKET_put_bytes(pkt, pcurves[1], 1)) {
+                if (!WPACKET_put_bytes_u8(pkt, pcurvestmp[0])
+                    || !WPACKET_put_bytes_u8(pkt, pcurvestmp[1])) {
                         SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT,
                                ERR_R_INTERNAL_ERROR);
                         return 0;
@@ -1140,7 +1166,7 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
 #endif                          /* OPENSSL_NO_EC */
 
     if (tls_use_ticket(s)) {
-        int ticklen;
+        size_t ticklen;
         if (!s->new_session && s->session && s->session->tlsext_tick)
             ticklen = s->session->tlsext_ticklen;
         else if (s->session && s->tlsext_session_ticket &&
@@ -1160,7 +1186,7 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
             s->tlsext_session_ticket->data == NULL)
             goto skip_ext;
 
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_session_ticket, 2)
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_session_ticket)
                 || !WPACKET_sub_memcpy_u16(pkt, s->session->tlsext_tick,
                                            ticklen)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
@@ -1175,7 +1201,7 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
 
         salglen = tls12_get_psigalgs(s, &salg);
 
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_signature_algorithms, 2)
+        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 */
@@ -1191,10 +1217,10 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
     if (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp) {
         int i;
 
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_status_request, 2)
+        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(pkt, TLSEXT_STATUSTYPE_ocsp, 1)
+                || !WPACKET_put_bytes_u8(pkt, TLSEXT_STATUSTYPE_ocsp)
                    /* Sub-packet for the ids */
                 || !WPACKET_start_sub_packet_u16(pkt)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
@@ -1209,7 +1235,7 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
             idlen = i2d_OCSP_RESPID(id, NULL);
             if (idlen <= 0
                        /* Sub-packet for an individual id */
-                    || !WPACKET_sub_allocate_bytes_u8(pkt, idlen, &idbytes)
+                    || !WPACKET_sub_allocate_bytes_u16(pkt, idlen, &idbytes)
                     || i2d_OCSP_RESPID(id, &idbytes) != idlen) {
                 SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
                 return 0;
@@ -1241,30 +1267,6 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
         }
     }
 #endif
-#ifndef OPENSSL_NO_HEARTBEATS
-    if (SSL_IS_DTLS(s)) {
-        unsigned int mode;
-
-        /*-
-         * Set mode:
-         * 1: peer may send requests
-         * 2: peer not allowed to send requests
-         */
-        if (s->tlsext_heartbeat & SSL_DTLSEXT_HB_DONT_RECV_REQUESTS)
-            mode = SSL_DTLSEXT_HB_DONT_SEND_REQUESTS;
-        else
-            mode = SSL_DTLSEXT_HB_ENABLED;
-
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_heartbeat, 2)
-                   /* Sub-packet for Hearbeat extension */
-                || !WPACKET_start_sub_packet_u16(pkt)
-                || !WPACKET_put_bytes(pkt, mode, 1)
-                || !WPACKET_close(pkt)) {
-            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-            return 0;
-        }
-    }
-#endif
 
 #ifndef OPENSSL_NO_NEXTPROTONEG
     if (s->ctx->next_proto_select_cb && !s->s3->tmp.finish_md_len) {
@@ -1272,8 +1274,8 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
          * The client advertises an empty extension to indicate its support
          * for Next Protocol Negotiation
          */
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_next_proto_neg, 2)
-                || !WPACKET_put_bytes(pkt, 0, 2)) {
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_next_proto_neg)
+                || !WPACKET_put_bytes_u16(pkt, 0)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
             return 0;
         }
@@ -1286,8 +1288,8 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
      * (see longer comment below)
      */
     if (s->alpn_client_proto_list && !s->s3->tmp.finish_md_len) {
-        if (!WPACKET_put_bytes(pkt,
-                    TLSEXT_TYPE_application_layer_protocol_negotiation, 2)
+        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->alpn_client_proto_list,
@@ -1300,11 +1302,11 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
     }
 #ifndef OPENSSL_NO_SRTP
     if (SSL_IS_DTLS(s) && SSL_get_srtp_profiles(s)) {
-        STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = 0;
+        STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = SSL_get_srtp_profiles(s);
         SRTP_PROTECTION_PROFILE *prof;
         int i, ct;
 
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_use_srtp, 2)
+        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 */
@@ -1315,12 +1317,15 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
         ct = sk_SRTP_PROTECTION_PROFILE_num(clnt);
         for (i = 0; i < ct; i++) {
             prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i);
-            if (prof == NULL || !WPACKET_put_bytes(pkt, prof->id, 2)) {
+            if (prof == NULL || !WPACKET_put_bytes_u16(pkt, prof->id)) {
                 SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
                 return 0;
             }
         }
-        if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+        if (!WPACKET_close(pkt)
+                   /* Add an empty use_mki value */
+                || !WPACKET_put_bytes_u8(pkt, 0)
+                || !WPACKET_close(pkt)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
             return 0;
         }
@@ -1333,28 +1338,147 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
         return 0;
     }
 
-    if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_encrypt_then_mac, 2)
-            || !WPACKET_put_bytes(pkt, 0, 2)) {
-        SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-        return 0;
+    if (!(s->options & SSL_OP_NO_ENCRYPT_THEN_MAC)) {
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_encrypt_then_mac)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
+            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
 
 #ifndef OPENSSL_NO_CT
     if (s->ct_validation_callback != NULL) {
-        if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_signed_certificate_timestamp, 2)
-                || !WPACKET_put_bytes(pkt, 0, 2)) {
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_signed_certificate_timestamp)
+                || !WPACKET_put_bytes_u16(pkt, 0)) {
             SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
             return 0;
         }
     }
 #endif
 
-    if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_extended_master_secret, 2)
-            || !WPACKET_put_bytes(pkt, 0, 2)) {
+    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_extended_master_secret)
+            || !WPACKET_put_bytes_u16(pkt, 0)) {
         SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
         return 0;
     }
 
+    reason = ssl_get_client_min_max_version(s, &min_version, &max_version);
+    if (reason != 0) {
+        SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, reason);
+        return 0;
+    }
+
+    /* TLS1.3 specific extensions */
+    if (!SSL_IS_DTLS(s) && max_version >= TLS1_3_VERSION) {
+        int currv;
+        size_t i, sharessent = 0;
+
+        /* TODO(TLS1.3): Should we add this extension for versions < TLS1.3? */
+        /* supported_versions extension */
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_supported_versions)
+                || !WPACKET_start_sub_packet_u16(pkt)
+                || !WPACKET_start_sub_packet_u8(pkt)) {
+            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+
+        /*
+         * TODO(TLS1.3): There is some discussion on the TLS list as to wheter
+         * 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)) {
+                    SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT,
+                           ERR_R_INTERNAL_ERROR);
+                    return 0;
+                }
+            } else if (!WPACKET_put_bytes_u16(pkt, currv)) {
+                SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+                return 0;
+            }
+        }
+        if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 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)) {
+            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+
+        /*
+         * TODO(TLS1.3): Make the number of key_shares sent configurable. For
+         * now, just send one
+         */
+        for (i = 0; i < num_curves && sharessent < 1; i++, pcurves += 2) {
+            unsigned char *encodedPoint = NULL;
+            unsigned int curve_id = 0;
+            EVP_PKEY *key_share_key = NULL;
+            size_t encodedlen;
+
+            if (!tls_curve_allowed(s, pcurves, SSL_SECOP_CURVE_SUPPORTED))
+                continue;
+
+            if (s->s3->tmp.pkey != NULL) {
+                /* Shouldn't happen! */
+                SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT,
+                       ERR_R_INTERNAL_ERROR);
+                return 0;
+            }
+
+            /* Generate a key for this key_share */
+            curve_id = (pcurves[0] << 8) | pcurves[1];
+            key_share_key = ssl_generate_pkey_curve(curve_id);
+            if (key_share_key == NULL) {
+                SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_EVP_LIB);
+                return 0;
+            }
+
+            /* Encode the public key. */
+            encodedlen = EVP_PKEY_get1_tls_encodedpoint(key_share_key,
+                                                        &encodedPoint);
+            if (encodedlen == 0) {
+                SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_EC_LIB);
+                EVP_PKEY_free(key_share_key);
+                return 0;
+            }
+
+            /* Create KeyShareEntry */
+            if (!WPACKET_put_bytes_u16(pkt, curve_id)
+                    || !WPACKET_sub_memcpy_u16(pkt, encodedPoint, encodedlen)) {
+                SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT,
+                       ERR_R_INTERNAL_ERROR);
+                EVP_PKEY_free(key_share_key);
+                OPENSSL_free(encodedPoint);
+                return 0;
+            }
+
+            /*
+             * 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->group_id = curve_id;
+            s->s3->tmp.pkey = key_share_key;
+            sharessent++;
+            OPENSSL_free(encodedPoint);
+        }
+        if (!WPACKET_close(pkt) || !WPACKET_close(pkt)) {
+            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
+    }
+
     /*
      * Add padding to workaround bugs in F5 terminators. See
      * https://tools.ietf.org/html/draft-agl-tls-padding-03 NB: because this
@@ -1377,7 +1501,7 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
             else
                 hlen = 0;
 
-            if (!WPACKET_put_bytes(pkt, TLSEXT_TYPE_padding, 2)
+            if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_padding)
                     || !WPACKET_sub_allocate_bytes_u16(pkt, hlen, &padbytes)) {
                 SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
                 return 0;
@@ -1390,12 +1514,61 @@ int ssl_add_clienthello_tlsext(SSL *s, WPACKET *pkt, int *al)
     return 1;
 }
 
-unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
-                                          unsigned char *limit, int *al)
+/*
+ * Add the key_share extension.
+ *
+ * Returns 1 on success or 0 on failure.
+ */
+static int add_client_key_share_ext(SSL *s, WPACKET *pkt, int *al)
+{
+    unsigned char *encodedPoint;
+    size_t encoded_pt_len = 0;
+    EVP_PKEY *ckey = s->s3->peer_tmp, *skey = NULL;
+
+    if (ckey == NULL) {
+        SSLerr(SSL_F_ADD_CLIENT_KEY_SHARE_EXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    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_ADD_CLIENT_KEY_SHARE_EXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    skey = ssl_generate_pkey(ckey);
+
+    /* Generate encoding of server key */
+    encoded_pt_len = EVP_PKEY_get1_tls_encodedpoint(skey, &encodedPoint);
+    if (encoded_pt_len == 0) {
+        SSLerr(SSL_F_ADD_CLIENT_KEY_SHARE_EXT, 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_ADD_CLIENT_KEY_SHARE_EXT, 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) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_ADD_CLIENT_KEY_SHARE_EXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
+int ssl_add_serverhello_tlsext(SSL *s, WPACKET *pkt, int *al)
 {
-    int extdatalen = 0;
-    unsigned char *orig = buf;
-    unsigned char *ret = buf;
 #ifndef OPENSSL_NO_NEXTPROTONEG
     int next_proto_neg_seen;
 #endif
@@ -1406,30 +1579,16 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
     using_ecc = using_ecc && (s->session->tlsext_ecpointformatlist != NULL);
 #endif
 
-    ret += 2;
-    if (ret >= limit)
-        return NULL;            /* this really never occurs, but ... */
-
-    if (s->s3->send_connection_binding) {
-        int el;
-
-        if (!ssl_add_serverhello_renegotiate_ext(s, 0, &el, 0)) {
-            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-            return NULL;
-        }
-
-        if ((limit - ret - 4 - el) < 0)
-            return NULL;
-
-        s2n(TLSEXT_TYPE_renegotiate, ret);
-        s2n(el, ret);
-
-        if (!ssl_add_serverhello_renegotiate_ext(s, ret, &el, el)) {
-            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-            return NULL;
-        }
+    if (!WPACKET_start_sub_packet_u16(pkt)
+            || !WPACKET_set_flags(pkt, WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH)) {
+        SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
 
-        ret += el;
+    if (s->s3->send_connection_binding &&
+            !ssl_add_serverhello_renegotiate_ext(s, pkt)) {
+        SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+        return 0;
     }
 
     /* Only add RI for SSLv3 */
@@ -1437,12 +1596,12 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
         goto done;
 
     if (!s->hit && s->servername_done == 1
-        && s->session->tlsext_hostname != NULL) {
-        if ((long)(limit - ret - 4) < 0)
-            return NULL;
-
-        s2n(TLSEXT_TYPE_server_name, ret);
-        s2n(0, ret);
+            && s->session->tlsext_hostname != NULL) {
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_server_name)
+                || !WPACKET_put_bytes_u16(pkt, 0)) {
+            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
 #ifndef OPENSSL_NO_EC
     if (using_ecc) {
@@ -1451,25 +1610,15 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
         /*
          * Add TLS extension ECPointFormats to the ServerHello message
          */
-        long lenmax;
-
         tls1_get_formatlist(s, &plist, &plistlen);
 
-        if ((lenmax = limit - ret - 5) < 0)
-            return NULL;
-        if (plistlen > (size_t)lenmax)
-            return NULL;
-        if (plistlen > 255) {
+        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_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-            return NULL;
+            return 0;
         }
-
-        s2n(TLSEXT_TYPE_ec_point_formats, ret);
-        s2n(plistlen + 1, ret);
-        *(ret++) = (unsigned char)plistlen;
-        memcpy(ret, plist, plistlen);
-        ret += plistlen;
-
     }
     /*
      * Currently the server should not respond with a SupportedCurves
@@ -1478,10 +1627,11 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
 #endif                          /* OPENSSL_NO_EC */
 
     if (s->tlsext_ticket_expected && tls_use_ticket(s)) {
-        if ((long)(limit - ret - 4) < 0)
-            return NULL;
-        s2n(TLSEXT_TYPE_session_ticket, ret);
-        s2n(0, ret);
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_session_ticket)
+                || !WPACKET_put_bytes_u16(pkt, 0)) {
+            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     } else {
         /*
          * if we don't add the above TLSEXT, we can't add a session ticket
@@ -1491,31 +1641,23 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
     }
 
     if (s->tlsext_status_expected) {
-        if ((long)(limit - ret - 4) < 0)
-            return NULL;
-        s2n(TLSEXT_TYPE_status_request, ret);
-        s2n(0, ret);
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_status_request)
+                || !WPACKET_put_bytes_u16(pkt, 0)) {
+            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
 #ifndef OPENSSL_NO_SRTP
     if (SSL_IS_DTLS(s) && s->srtp_profile) {
-        int el;
-
-        /* Returns 0 on success!! */
-        if (ssl_add_serverhello_use_srtp_ext(s, 0, &el, 0)) {
-            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-            return NULL;
-        }
-        if ((limit - ret - 4 - el) < 0)
-            return NULL;
-
-        s2n(TLSEXT_TYPE_use_srtp, ret);
-        s2n(el, ret);
-
-        if (ssl_add_serverhello_use_srtp_ext(s, ret, &el, el)) {
+        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_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
-            return NULL;
+            return 0;
         }
-        ret += el;
     }
 #endif
 
@@ -1530,31 +1672,11 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
             0x2a, 0x85, 0x03, 0x02, 0x02, 0x16, 0x30, 0x08,
             0x06, 0x06, 0x2a, 0x85, 0x03, 0x02, 0x02, 0x17
         };
-        if (limit - ret < 36)
-            return NULL;
-        memcpy(ret, cryptopro_ext, 36);
-        ret += 36;
-
-    }
-#ifndef OPENSSL_NO_HEARTBEATS
-    /* Add Heartbeat extension if we've received one */
-    if (SSL_IS_DTLS(s) && (s->tlsext_heartbeat & SSL_DTLSEXT_HB_ENABLED)) {
-        if ((limit - ret - 4 - 1) < 0)
-            return NULL;
-        s2n(TLSEXT_TYPE_heartbeat, ret);
-        s2n(1, ret);
-        /*-
-         * Set mode:
-         * 1: peer may send requests
-         * 2: peer not allowed to send requests
-         */
-        if (s->tlsext_heartbeat & SSL_DTLSEXT_HB_DONT_RECV_REQUESTS)
-            *(ret++) = SSL_DTLSEXT_HB_DONT_SEND_REQUESTS;
-        else
-            *(ret++) = SSL_DTLSEXT_HB_ENABLED;
-
+        if (!WPACKET_memcpy(pkt, cryptopro_ext, sizeof(cryptopro_ext))) {
+            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
-#endif
 
 #ifndef OPENSSL_NO_NEXTPROTONEG
     next_proto_neg_seen = s->s3->next_proto_neg_seen;
@@ -1568,18 +1690,24 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
                                               s->
                                               ctx->next_protos_advertised_cb_arg);
         if (r == SSL_TLSEXT_ERR_OK) {
-            if ((long)(limit - ret - 4 - npalen) < 0)
-                return NULL;
-            s2n(TLSEXT_TYPE_next_proto_neg, ret);
-            s2n(npalen, ret);
-            memcpy(ret, npa, npalen);
-            ret += npalen;
+            if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_next_proto_neg)
+                    || !WPACKET_sub_memcpy_u16(pkt, npa, npalen)) {
+                SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+                return 0;
+            }
             s->s3->next_proto_neg_seen = 1;
         }
     }
 #endif
-    if (!custom_ext_add_old(s, 1, &ret, limit, al))
-        return NULL;
+
+    if (SSL_IS_TLS13(s) && !s->hit && !add_client_key_share_ext(s, pkt, al))
+        return 0;
+
+    if (!custom_ext_add(s, 1, pkt, al)) {
+        SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
     if (s->s3->flags & TLS1_FLAGS_ENCRYPT_THEN_MAC) {
         /*
          * Don't use encrypt_then_mac if AEAD or RC4 might want to disable
@@ -1591,36 +1719,41 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
             || s->s3->tmp.new_cipher->algorithm_enc == SSL_eGOST2814789CNT12)
             s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
         else {
-            s2n(TLSEXT_TYPE_encrypt_then_mac, ret);
-            s2n(0, ret);
+            if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_encrypt_then_mac)
+                    || !WPACKET_put_bytes_u16(pkt, 0)) {
+                SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+                return 0;
+            }
         }
     }
     if (s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) {
-        s2n(TLSEXT_TYPE_extended_master_secret, ret);
-        s2n(0, ret);
+        if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_extended_master_secret)
+                || !WPACKET_put_bytes_u16(pkt, 0)) {
+            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
 
     if (s->s3->alpn_selected != NULL) {
-        const unsigned char *selected = s->s3->alpn_selected;
-        unsigned int len = s->s3->alpn_selected_len;
-
-        if ((long)(limit - ret - 4 - 2 - 1 - len) < 0)
-            return NULL;
-        s2n(TLSEXT_TYPE_application_layer_protocol_negotiation, ret);
-        s2n(3 + len, ret);
-        s2n(1 + len, ret);
-        *ret++ = len;
-        memcpy(ret, selected, len);
-        ret += len;
+        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_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
 
  done:
-
-    if ((extdatalen = ret - orig - 2) == 0)
-        return orig;
-
-    s2n(extdatalen, orig);
-    return ret;
+    if (!WPACKET_close(pkt)) {
+        SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+    return 1;
 }
 
 /*
@@ -1671,7 +1804,7 @@ static int tls1_alpn_handle_client_hello_late(SSL *s, int *al)
     if (s->ctx->alpn_select_cb != NULL && s->s3->alpn_proposed != NULL) {
         int r = s->ctx->alpn_select_cb(s, &selected, &selected_len,
                                        s->s3->alpn_proposed,
-                                       s->s3->alpn_proposed_len,
+                                       (unsigned int)s->s3->alpn_proposed_len,
                                        s->ctx->alpn_select_cb_arg);
 
         if (r == SSL_TLSEXT_ERR_OK) {
@@ -1698,7 +1831,7 @@ static int tls1_alpn_handle_client_hello_late(SSL *s, int *al)
 #ifndef OPENSSL_NO_EC
 /*-
  * ssl_check_for_safari attempts to fingerprint Safari using OS X
- * SecureTransport using the TLS extension block in |pkt|.
+ * SecureTransport using the TLS extension block in |hello|.
  * Safari, since 10.6, sends exactly these extensions, in this order:
  *   SNI,
  *   elliptic_curves
@@ -1709,7 +1842,7 @@ static int tls1_alpn_handle_client_hello_late(SSL *s, int *al)
  * Sadly we cannot differentiate 10.6, 10.7 and 10.8.4 (which work), from
  * 10.8..10.8.3 (which don't work).
  */
-static void ssl_check_for_safari(SSL *s, const PACKET *pkt)
+static void ssl_check_for_safari(SSL *s, const CLIENTHELLO_MSG *hello)
 {
     unsigned int type;
     PACKET sni, tmppkt;
@@ -1741,7 +1874,7 @@ static void ssl_check_for_safari(SSL *s, const PACKET *pkt)
     /* Length of the common prefix (first two extensions). */
     static const size_t kSafariCommonExtensionsLength = 18;
 
-    tmppkt = *pkt;
+    tmppkt = hello->extensions;
 
     if (!PACKET_forward(&tmppkt, 2)
         || !PACKET_get_net_2(&tmppkt, &type)
@@ -1760,22 +1893,214 @@ static void ssl_check_for_safari(SSL *s, const PACKET *pkt)
 }
 #endif                          /* !OPENSSL_NO_EC */
 
+
 /*
- * Parse ClientHello extensions and stash extension info in various parts of
- * the SSL object. Verify that there are no duplicate extensions.
+ * Process the supported_groups extension if present. Returns success if the
+ * extension is absent, or if it has been successfully processed.
+ *
+ * Returns 1 on success or 0 on failure
+ */
+static int tls_process_supported_groups(SSL *s, CLIENTHELLO_MSG *hello)
+{
+#ifndef OPENSSL_NO_EC
+    PACKET supported_groups_list;
+    RAW_EXTENSION *suppgroups = tls_get_extension_by_type(hello->pre_proc_exts,
+                                    hello->num_extensions,
+                                    TLSEXT_TYPE_supported_groups);
+
+    if (suppgroups == NULL)
+        return 1;
+
+    /* Each group is 2 bytes and we must have at least 1. */
+    if (!PACKET_as_length_prefixed_2(&suppgroups->data,
+                                     &supported_groups_list)
+        || PACKET_remaining(&supported_groups_list) == 0
+        || (PACKET_remaining(&supported_groups_list) % 2) != 0) {
+        return 0;
+    }
+
+    if (!s->hit
+            && !PACKET_memdup(&supported_groups_list,
+                              &s->session->tlsext_supportedgroupslist,
+                              &s->session->tlsext_supportedgroupslist_length)) {
+        return 0;
+    }
+#endif
+    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.
+ */
+static int check_in_list(SSL *s, unsigned int group_id,
+                         const unsigned char *groups, size_t num_groups,
+                         int checkallow)
+{
+    size_t i;
+
+    if (groups == NULL || num_groups == 0)
+        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;
+        }
+    }
+
+    /* If i == num_groups then not in the list */
+    return i < num_groups;
+}
+
+/*
+ * Process a key_share 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 process_key_share_ext(SSL *s, PACKET *pkt, int *al)
+{
+    unsigned int group_id;
+    PACKET key_share_list, encoded_pt;
+    const unsigned char *clntcurves, *srvrcurves;
+    size_t clnt_num_curves, srvr_num_curves;
+    int group_nid, found = 0;
+    unsigned int curve_flags;
+
+    /* Sanity check */
+    if (s->s3->peer_tmp != NULL) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    if (!PACKET_as_length_prefixed_2(pkt, &key_share_list)) {
+        *al = SSL_AD_HANDSHAKE_FAILURE;
+        SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT,
+               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_PROCESS_KEY_SHARE_EXT,
+               ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    /* Get the clients list of supported curves */
+    if (!tls1_get_curvelist(s, 1, &clntcurves, &clnt_num_curves)) {
+        *al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT,
+               ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+
+    while (PACKET_remaining(&key_share_list) > 0) {
+        if (!PACKET_get_net_2(&key_share_list, &group_id)
+                || !PACKET_get_length_prefixed_2(&key_share_list, &encoded_pt)
+                || PACKET_remaining(&encoded_pt) == 0) {
+            *al = SSL_AD_HANDSHAKE_FAILURE;
+            SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT,
+                   SSL_R_LENGTH_MISMATCH);
+            return 0;
+        }
+
+        /*
+         * If we already found a suitable key_share we loop through the
+         * rest to verify the structure, but don't process them.
+         */
+        if (found)
+            continue;
+
+        /* 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_PROCESS_KEY_SHARE_EXT,
+                   SSL_R_BAD_KEY_SHARE);
+            return 0;
+        }
+
+        /* Check if this share is for a group we can use */
+        if (!check_in_list(s, group_id, srvrcurves, srvr_num_curves, 1)) {
+            /* Share not suitable */
+            continue;
+        }
+
+        group_nid = tls1_ec_curve_id2nid(group_id, &curve_flags);
+
+        if (group_nid == 0) {
+            *al = SSL_AD_INTERNAL_ERROR;
+            SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT,
+                   SSL_R_UNABLE_TO_FIND_ECDH_PARAMETERS);
+            return 0;
+        }
+
+        if ((curve_flags & TLS_CURVE_TYPE) == TLS_CURVE_CUSTOM) {
+            /* Can happen for some curves, e.g. X25519 */
+            EVP_PKEY *key = EVP_PKEY_new();
+
+            if (key == NULL || !EVP_PKEY_set_type(key, group_nid)) {
+                *al = SSL_AD_INTERNAL_ERROR;
+                SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT, ERR_R_EVP_LIB);
+                EVP_PKEY_free(key);
+                return 0;
+            }
+            s->s3->peer_tmp = key;
+        } 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_PROCESS_KEY_SHARE_EXT, ERR_R_EVP_LIB);
+                EVP_PKEY_CTX_free(pctx);
+                return 0;
+            }
+            EVP_PKEY_CTX_free(pctx);
+            pctx = NULL;
+        }
+        s->s3->group_id = group_id;
+
+        if (!EVP_PKEY_set1_tls_encodedpoint(s->s3->peer_tmp,
+                PACKET_data(&encoded_pt),
+                PACKET_remaining(&encoded_pt))) {
+            *al = SSL_AD_DECODE_ERROR;
+            SSLerr(SSL_F_PROCESS_KEY_SHARE_EXT, SSL_R_BAD_ECPOINT);
+            return 0;
+        }
+
+        found = 1;
+    }
+
+    return 1;
+}
+
+/*
+ * Loop through all remaining ClientHello extensions that we collected earlier
+ * and haven't already processed. For each one parse it and update the SSL
+ * object as required.
  *
  * Behaviour upon resumption is extension-specific. If the extension has no
  * effect during resumption, it is parsed (to verify its format) but otherwise
  * ignored.
  *
- * Consumes the entire packet in |pkt|. Returns 1 on success and 0 on failure.
+ * Returns 1 on success and 0 on failure.
  * Upon failure, sets |al| to the appropriate alert.
  */
-static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
+static int ssl_scan_clienthello_tlsext(SSL *s, CLIENTHELLO_MSG *hello, int *al)
 {
-    unsigned int type;
+    size_t loop;
     int renegotiate_seen = 0;
-    PACKET extensions;
 
     *al = SSL_AD_DECODE_ERROR;
     s->servername_done = 0;
@@ -1790,14 +2115,10 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
     OPENSSL_free(s->s3->alpn_proposed);
     s->s3->alpn_proposed = NULL;
     s->s3->alpn_proposed_len = 0;
-#ifndef OPENSSL_NO_HEARTBEATS
-    s->tlsext_heartbeat &= ~(SSL_DTLSEXT_HB_ENABLED |
-                             SSL_DTLSEXT_HB_DONT_SEND_REQUESTS);
-#endif
 
 #ifndef OPENSSL_NO_EC
     if (s->options & SSL_OP_SAFARI_ECDHE_ECDSA_BUG)
-        ssl_check_for_safari(s, pkt);
+        ssl_check_for_safari(s, hello);
 #endif                          /* !OPENSSL_NO_EC */
 
     /* Clear any signature algorithms extension received */
@@ -1812,32 +2133,32 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
 
     s->srtp_profile = NULL;
 
-    if (PACKET_remaining(pkt) == 0)
-        goto ri_check;
-
-    if (!PACKET_as_length_prefixed_2(pkt, &extensions))
-        return 0;
-
-    if (!tls1_check_duplicate_extensions(&extensions))
+    /*
+     * We process the supported_groups extension first so that is done before
+     * we get to key_share which needs to use the information in it.
+     */
+    if (!tls_process_supported_groups(s, hello)) {
+        *al = TLS1_AD_INTERNAL_ERROR;
         return 0;
+    }
 
     /*
      * We parse all extensions to ensure the ClientHello is well-formed but,
      * unless an extension specifies otherwise, we ignore extensions upon
      * resumption.
      */
-    while (PACKET_get_net_2(&extensions, &type)) {
-        PACKET extension;
-        if (!PACKET_get_length_prefixed_2(&extensions, &extension))
-            return 0;
+    for (loop = 0; loop < hello->num_extensions; loop++) {
+        RAW_EXTENSION *currext = &hello->pre_proc_exts[loop];
 
         if (s->tlsext_debug_cb)
-            s->tlsext_debug_cb(s, 0, type, PACKET_data(&extension),
-                               PACKET_remaining(&extension),
+            s->tlsext_debug_cb(s, 0, currext->type,
+                               PACKET_data(&currext->data),
+                               PACKET_remaining(&currext->data),
                                s->tlsext_debug_arg);
 
-        if (type == TLSEXT_TYPE_renegotiate) {
-            if (!ssl_parse_clienthello_renegotiate_ext(s, &extension, al))
+        if (currext->type == TLSEXT_TYPE_renegotiate) {
+            if (!ssl_parse_clienthello_renegotiate_ext(s,
+                    &currext->data, al))
                 return 0;
             renegotiate_seen = 1;
         } else if (s->version == SSL3_VERSION) {
@@ -1867,11 +2188,11 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
  *
  */
 
-        else if (type == TLSEXT_TYPE_server_name) {
+        else if (currext->type == TLSEXT_TYPE_server_name) {
             unsigned int servname_type;
             PACKET sni, hostname;
 
-            if (!PACKET_as_length_prefixed_2(&extension, &sni)
+            if (!PACKET_as_length_prefixed_2(&currext->data, &sni)
                 /* ServerNameList must be at least 1 byte long. */
                 || PACKET_remaining(&sni) == 0) {
                 return 0;
@@ -1923,10 +2244,10 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
             }
         }
 #ifndef OPENSSL_NO_SRP
-        else if (type == TLSEXT_TYPE_srp) {
+        else if (currext->type == TLSEXT_TYPE_srp) {
             PACKET srp_I;
 
-            if (!PACKET_as_length_prefixed_1(&extension, &srp_I))
+            if (!PACKET_as_length_prefixed_1(&currext->data, &srp_I))
                 return 0;
 
             if (PACKET_contains_zero_byte(&srp_I))
@@ -1944,10 +2265,11 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
 #endif
 
 #ifndef OPENSSL_NO_EC
-        else if (type == TLSEXT_TYPE_ec_point_formats) {
+        else if (currext->type == TLSEXT_TYPE_ec_point_formats) {
             PACKET ec_point_format_list;
 
-            if (!PACKET_as_length_prefixed_1(&extension, &ec_point_format_list)
+            if (!PACKET_as_length_prefixed_1(&currext->data,
+                                             &ec_point_format_list)
                 || PACKET_remaining(&ec_point_format_list) == 0) {
                 return 0;
             }
@@ -1961,40 +2283,23 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                     return 0;
                 }
             }
-        } else if (type == TLSEXT_TYPE_elliptic_curves) {
-            PACKET elliptic_curve_list;
-
-            /* Each NamedCurve is 2 bytes and we must have at least 1. */
-            if (!PACKET_as_length_prefixed_2(&extension, &elliptic_curve_list)
-                || PACKET_remaining(&elliptic_curve_list) == 0
-                || (PACKET_remaining(&elliptic_curve_list) % 2) != 0) {
-                return 0;
-            }
-
-            if (!s->hit) {
-                if (!PACKET_memdup(&elliptic_curve_list,
-                                   &s->session->tlsext_ellipticcurvelist,
-                                   &s->
-                                   session->tlsext_ellipticcurvelist_length)) {
-                    *al = TLS1_AD_INTERNAL_ERROR;
-                    return 0;
-                }
-            }
         }
 #endif                          /* OPENSSL_NO_EC */
-        else if (type == TLSEXT_TYPE_session_ticket) {
+        else if (currext->type == TLSEXT_TYPE_session_ticket
+                && !SSL_IS_TLS13(s)) {
             if (s->tls_session_ticket_ext_cb &&
-                !s->tls_session_ticket_ext_cb(s, PACKET_data(&extension),
-                                              PACKET_remaining(&extension),
-                                              s->tls_session_ticket_ext_cb_arg))
-            {
+                !s->tls_session_ticket_ext_cb(s,
+                    PACKET_data(&currext->data),
+                    PACKET_remaining(&currext->data),
+                    s->tls_session_ticket_ext_cb_arg)) {
                 *al = TLS1_AD_INTERNAL_ERROR;
                 return 0;
             }
-        } else if (type == TLSEXT_TYPE_signature_algorithms) {
+        } else if (currext->type == TLSEXT_TYPE_signature_algorithms) {
             PACKET supported_sig_algs;
 
-            if (!PACKET_as_length_prefixed_2(&extension, &supported_sig_algs)
+            if (!PACKET_as_length_prefixed_2(&currext->data,
+                                             &supported_sig_algs)
                 || (PACKET_remaining(&supported_sig_algs) % 2) != 0
                 || PACKET_remaining(&supported_sig_algs) == 0) {
                 return 0;
@@ -2006,8 +2311,8 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                     return 0;
                 }
             }
-        } else if (type == TLSEXT_TYPE_status_request) {
-            if (!PACKET_get_1(&extension,
+        } else if (currext->type == TLSEXT_TYPE_status_request) {
+            if (!PACKET_get_1(&currext->data,
                               (unsigned int *)&s->tlsext_status_type)) {
                 return 0;
             }
@@ -2016,9 +2321,25 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                 const unsigned char *ext_data;
                 PACKET responder_id_list, exts;
                 if (!PACKET_get_length_prefixed_2
-                    (&extension, &responder_id_list))
+                    (&currext->data, &responder_id_list))
                     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->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;
+                }
+
                 while (PACKET_remaining(&responder_id_list) > 0) {
                     OCSP_RESPID *id;
                     PACKET responder_id;
@@ -2030,16 +2351,10 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                         return 0;
                     }
 
-                    if (s->tlsext_ocsp_ids == NULL
-                        && (s->tlsext_ocsp_ids =
-                            sk_OCSP_RESPID_new_null()) == NULL) {
-                        *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,
-                                         PACKET_remaining(&responder_id));
+                                         (int)PACKET_remaining(&responder_id));
                     if (id == NULL)
                         return 0;
 
@@ -2056,7 +2371,8 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                 }
 
                 /* Read in request_extensions */
-                if (!PACKET_as_length_prefixed_2(&extension, &exts))
+                if (!PACKET_as_length_prefixed_2(
+                        &currext->data, &exts))
                     return 0;
 
                 if (PACKET_remaining(&exts) > 0) {
@@ -2065,7 +2381,7 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                                                X509_EXTENSION_free);
                     s->tlsext_ocsp_exts =
                         d2i_X509_EXTENSIONS(NULL, &ext_data,
-                                            PACKET_remaining(&exts));
+                                            (int)PACKET_remaining(&exts));
                     if (s->tlsext_ocsp_exts == NULL
                         || ext_data != PACKET_end(&exts)) {
                         return 0;
@@ -2080,32 +2396,9 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
                 s->tlsext_status_type = -1;
             }
         }
-#ifndef OPENSSL_NO_HEARTBEATS
-        else if (SSL_IS_DTLS(s) && type == TLSEXT_TYPE_heartbeat) {
-            unsigned int hbtype;
-
-            if (!PACKET_get_1(&extension, &hbtype)
-                || PACKET_remaining(&extension)) {
-                *al = SSL_AD_DECODE_ERROR;
-                return 0;
-            }
-            switch (hbtype) {
-            case 0x01:         /* Client allows us to send HB requests */
-                s->tlsext_heartbeat |= SSL_DTLSEXT_HB_ENABLED;
-                break;
-            case 0x02:         /* Client doesn't accept HB requests */
-                s->tlsext_heartbeat |= SSL_DTLSEXT_HB_ENABLED;
-                s->tlsext_heartbeat |= SSL_DTLSEXT_HB_DONT_SEND_REQUESTS;
-                break;
-            default:
-                *al = SSL_AD_ILLEGAL_PARAMETER;
-                return 0;
-            }
-        }
-#endif
 #ifndef OPENSSL_NO_NEXTPROTONEG
-        else if (type == TLSEXT_TYPE_next_proto_neg &&
-                 s->s3->tmp.finish_md_len == 0) {
+        else if (currext->type == TLSEXT_TYPE_next_proto_neg
+                 && s->s3->tmp.finish_md_len == 0) {
             /*-
              * We shouldn't accept this extension on a
              * renegotiation.
@@ -2127,25 +2420,34 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
         }
 #endif
 
-        else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation &&
-                 s->s3->tmp.finish_md_len == 0) {
-            if (!tls1_alpn_handle_client_hello(s, &extension, al))
+        else if (currext->type
+                     == TLSEXT_TYPE_application_layer_protocol_negotiation
+                 && s->s3->tmp.finish_md_len == 0) {
+            if (!tls1_alpn_handle_client_hello(s,
+                    &currext->data, al))
                 return 0;
         }
 
         /* session ticket processed earlier */
 #ifndef OPENSSL_NO_SRTP
         else if (SSL_IS_DTLS(s) && SSL_get_srtp_profiles(s)
-                 && type == TLSEXT_TYPE_use_srtp) {
-            if (ssl_parse_clienthello_use_srtp_ext(s, &extension, al))
+                 && currext->type == TLSEXT_TYPE_use_srtp) {
+            if (ssl_parse_clienthello_use_srtp_ext(s,
+                    &currext->data, al))
                 return 0;
         }
 #endif
-        else if (type == TLSEXT_TYPE_encrypt_then_mac)
+        else if (currext->type == TLSEXT_TYPE_encrypt_then_mac
+                 && !(s->options & SSL_OP_NO_ENCRYPT_THEN_MAC)) {
             s->s3->flags |= TLS1_FLAGS_ENCRYPT_THEN_MAC;
+        } else if (currext->type == TLSEXT_TYPE_key_share
+                   && SSL_IS_TLS13(s) && !s->hit
+                   && !process_key_share_ext(s, &currext->data, al)) {
+            return 0;
+        }
         /*
          * Note: extended master secret extension handled in
-         * tls_check_serverhello_tlsext_early()
+         * tls_check_client_ems_support()
          */
 
         /*
@@ -2156,22 +2458,13 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
          * ServerHello may be later returned.
          */
         else if (!s->hit) {
-            if (custom_ext_parse(s, 1, type, PACKET_data(&extension),
-                                 PACKET_remaining(&extension), al) <= 0)
+            if (custom_ext_parse(s, 1, currext->type,
+                    PACKET_data(&currext->data),
+                    PACKET_remaining(&currext->data), al) <= 0)
                 return 0;
         }
     }
 
-    if (PACKET_remaining(pkt) != 0) {
-        /*
-         * tls1_check_duplicate_extensions should ensure this never happens.
-         */
-        *al = SSL_AD_INTERNAL_ERROR;
-        return 0;
-    }
-
- ri_check:
-
     /* Need RI if renegotiating */
 
     if (!renegotiate_seen && s->renegotiate &&
@@ -2191,11 +2484,11 @@ static int ssl_scan_clienthello_tlsext(SSL *s, PACKET *pkt, int *al)
     return 1;
 }
 
-int ssl_parse_clienthello_tlsext(SSL *s, PACKET *pkt)
+int ssl_parse_clienthello_tlsext(SSL *s, CLIENTHELLO_MSG *hello)
 {
     int al = -1;
     custom_ext_init(&s->cert->srv_ext);
-    if (ssl_scan_clienthello_tlsext(s, pkt, &al) <= 0) {
+    if (ssl_scan_clienthello_tlsext(s, hello, &al) <= 0) {
         ssl3_send_alert(s, SSL3_AL_FATAL, al);
         return 0;
     }
@@ -2239,10 +2532,6 @@ static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
 
     OPENSSL_free(s->s3->alpn_selected);
     s->s3->alpn_selected = NULL;
-#ifndef OPENSSL_NO_HEARTBEATS
-    s->tlsext_heartbeat &= ~(SSL_DTLSEXT_HB_ENABLED |
-                             SSL_DTLSEXT_HB_DONT_SEND_REQUESTS);
-#endif
 
     s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
 
@@ -2385,6 +2674,11 @@ static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
                 *al = TLS1_AD_INTERNAL_ERROR;
                 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 = TLS1_AD_INTERNAL_ERROR;
@@ -2427,27 +2721,6 @@ static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
             }
             s->s3->alpn_selected_len = len;
         }
-#ifndef OPENSSL_NO_HEARTBEATS
-        else if (SSL_IS_DTLS(s) && type == TLSEXT_TYPE_heartbeat) {
-            unsigned int hbtype;
-            if (!PACKET_get_1(&spkt, &hbtype)) {
-                *al = SSL_AD_DECODE_ERROR;
-                return 0;
-            }
-            switch (hbtype) {
-            case 0x01:         /* Server allows us to send HB requests */
-                s->tlsext_heartbeat |= SSL_DTLSEXT_HB_ENABLED;
-                break;
-            case 0x02:         /* Server doesn't accept HB requests */
-                s->tlsext_heartbeat |= SSL_DTLSEXT_HB_ENABLED;
-                s->tlsext_heartbeat |= SSL_DTLSEXT_HB_DONT_SEND_REQUESTS;
-                break;
-            default:
-                *al = SSL_AD_ILLEGAL_PARAMETER;
-                return 0;
-            }
-        }
-#endif
 #ifndef OPENSSL_NO_SRTP
         else if (SSL_IS_DTLS(s) && type == TLSEXT_TYPE_use_srtp) {
             if (ssl_parse_serverhello_use_srtp_ext(s, &spkt, al))
@@ -2456,19 +2729,74 @@ static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
 #endif
         else if (type == TLSEXT_TYPE_encrypt_then_mac) {
             /* Ignore if inappropriate ciphersuite */
-            if (s->s3->tmp.new_cipher->algorithm_mac != SSL_AEAD
+            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;
-        } else if (type == TLSEXT_TYPE_extended_master_secret) {
+        } else if (type == TLSEXT_TYPE_extended_master_secret &&
+                (SSL_IS_DTLS(s) || !SSL_IS_TLS13(s))) {
             s->s3->flags |= TLS1_FLAGS_RECEIVED_EXTMS;
             if (!s->hit)
                 s->session->flags |= SSL_SESS_FLAG_EXTMS;
-        }
+        } else if (type == TLSEXT_TYPE_key_share
+                && SSL_IS_TLS13(s)) {
+            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_SSL_SCAN_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+                return 0;
+            }
+
+            if (!PACKET_get_net_2(&spkt, &group_id)) {
+                *al = SSL_AD_HANDSHAKE_FAILURE;
+                SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT,
+                       SSL_R_LENGTH_MISMATCH);
+                return 0;
+            }
+
+            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_SSL_SCAN_SERVERHELLO_TLSEXT,
+                       SSL_R_BAD_KEY_SHARE);
+                return 0;
+            }
+
+            if (!PACKET_as_length_prefixed_2(&spkt, &encoded_pt)
+                    || PACKET_remaining(&encoded_pt) == 0) {
+                *al = SSL_AD_DECODE_ERROR;
+                SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT,
+                       SSL_R_LENGTH_MISMATCH);
+                return 0;
+            }
+
+            skey = ssl_generate_pkey(ckey);
+            if (!EVP_PKEY_set1_tls_encodedpoint(skey, PACKET_data(&encoded_pt),
+                                                PACKET_remaining(&encoded_pt))) {
+                *al = SSL_AD_DECODE_ERROR;
+                SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_BAD_ECPOINT);
+                return 0;
+            }
+
+            if (ssl_derive(s, ckey, skey, 1) == 0) {
+                *al = SSL_AD_INTERNAL_ERROR;
+                SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
+                EVP_PKEY_free(skey);
+                return 0;
+            }
+            EVP_PKEY_free(skey);
         /*
          * If this extension type was not otherwise handled, but matches a
          * custom_cli_ext_record, then send it to the c callback
          */
-        else if (custom_ext_parse(s, 0, type, data, size, al) <= 0)
+        else if (custom_ext_parse(s, 0, type, data, size, al) <= 0)
             return 0;
     }
 
@@ -2749,7 +3077,7 @@ int ssl_check_serverhello_tlsext(SSL *s)
      */
     OPENSSL_free(s->tlsext_ocsp_resp);
     s->tlsext_ocsp_resp = NULL;
-    s->tlsext_ocsp_resplen = -1;
+    s->tlsext_ocsp_resplen = 0;
 
     switch (ret) {
     case SSL_TLSEXT_ERR_ALERT_FATAL:
@@ -2784,16 +3112,33 @@ int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt)
     return 1;
 }
 
-/*-
- * Since the server cache lookup is done early on in the processing of the
- * ClientHello and other operations depend on the result some extensions
- * need to be handled at the same time.
+/*
+ * Given a list of extensions that we collected earlier, find one of a given
+ * type and return it.
  *
- * Two extensions are currently handled, session ticket and extended master
- * secret.
+ * |exts| is the set of extensions previously collected.
+ * |numexts| is the number of extensions that we have.
+ * |type| the type of the extension that we are looking for.
  *
- *   session_id: ClientHello session ID.
- *   ext: ClientHello extensions (including length prefix)
+ * Returns a pointer to the found RAW_EXTENSION data, or NULL if not found.
+ */
+RAW_EXTENSION *tls_get_extension_by_type(RAW_EXTENSION *exts, size_t numexts,
+                                         unsigned int type)
+{
+    size_t loop;
+
+    for (loop = 0; loop < numexts; loop++) {
+        if (exts[loop].type == type)
+            return &exts[loop];
+    }
+
+    return NULL;
+}
+
+/*-
+ * Gets the ticket information supplied by the client if any.
+ *
+ *   hello: The parsed ClientHello data
  *   ret: (output) on return, if a ticket was decrypted, then this is set to
  *       point to the resulting session.
  *
@@ -2817,116 +3162,108 @@ int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt)
  *   a session ticket or we couldn't use the one it gave us, or if
  *   s->ctx->tlsext_ticket_key_cb asked to renew the client's ticket.
  *   Otherwise, s->tlsext_ticket_expected is set to 0.
- *
- *   For extended master secret flag is set if the extension is present.
- *
  */
-int tls_check_serverhello_tlsext_early(SSL *s, const PACKET *ext,
-                                       const PACKET *session_id,
-                                       SSL_SESSION **ret)
+int tls_get_ticket_from_client(SSL *s, CLIENTHELLO_MSG *hello,
+                               SSL_SESSION **ret)
 {
-    unsigned int i;
-    PACKET local_ext = *ext;
-    int retv = -1;
-
-    int have_ticket = 0;
-    int use_ticket = tls_use_ticket(s);
+    int retv;
+    const unsigned char *etick;
+    size_t size;
+    RAW_EXTENSION *ticketext;
 
     *ret = NULL;
     s->tlsext_ticket_expected = 0;
-    s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
 
     /*
-     * If tickets disabled behave as if no ticket present to permit stateful
+     * If tickets disabled or not supported by the protocol version
+     * (e.g. TLSv1.3) behave as if no ticket present to permit stateful
      * resumption.
      */
-    if ((s->version <= SSL3_VERSION))
+    if (s->version <= SSL3_VERSION || !tls_use_ticket(s))
         return 0;
 
-    if (!PACKET_get_net_2(&local_ext, &i)) {
-        retv = 0;
-        goto end;
+    ticketext = tls_get_extension_by_type(hello->pre_proc_exts,
+                                          hello->num_extensions,
+                                          TLSEXT_TYPE_session_ticket);
+    if (ticketext == NULL)
+        return 0;
+
+    size = PACKET_remaining(&ticketext->data);
+    if (size == 0) {
+        /*
+         * The client will accept a ticket but doesn't currently have
+         * one.
+         */
+        s->tlsext_ticket_expected = 1;
+        return 1;
     }
-    while (PACKET_remaining(&local_ext) >= 4) {
-        unsigned int type, size;
+    if (s->tls_session_secret_cb) {
+        /*
+         * Indicate that the ticket couldn't be decrypted rather than
+         * generating the session from ticket now, trigger
+         * abbreviated handshake based on external mechanism to
+         * calculate the master secret later.
+         */
+        return 2;
+    }
+    if (!PACKET_get_bytes(&ticketext->data, &etick, size)) {
+        /* Shouldn't ever happen */
+        return -1;
+    }
+    retv = tls_decrypt_ticket(s, etick, size, hello->session_id,
+                           hello->session_id_len, ret);
+    switch (retv) {
+    case 2:            /* ticket couldn't be decrypted */
+        s->tlsext_ticket_expected = 1;
+        return 2;
 
-        if (!PACKET_get_net_2(&local_ext, &type)
-            || !PACKET_get_net_2(&local_ext, &size)) {
-            /* Shouldn't ever happen */
-            retv = -1;
-            goto end;
-        }
-        if (PACKET_remaining(&local_ext) < size) {
-            retv = 0;
-            goto end;
-        }
-        if (type == TLSEXT_TYPE_session_ticket && use_ticket) {
-            int r;
-            const unsigned char *etick;
+    case 3:            /* ticket was decrypted */
+        return 3;
 
-            /* Duplicate extension */
-            if (have_ticket != 0) {
-                retv = -1;
-                goto end;
-            }
-            have_ticket = 1;
+    case 4:            /* ticket decrypted but need to renew */
+        s->tlsext_ticket_expected = 1;
+        return 3;
 
-            if (size == 0) {
-                /*
-                 * The client will accept a ticket but doesn't currently have
-                 * one.
-                 */
-                s->tlsext_ticket_expected = 1;
-                retv = 1;
-                continue;
-            }
-            if (s->tls_session_secret_cb) {
-                /*
-                 * Indicate that the ticket couldn't be decrypted rather than
-                 * generating the session from ticket now, trigger
-                 * abbreviated handshake based on external mechanism to
-                 * calculate the master secret later.
-                 */
-                retv = 2;
-                continue;
-            }
-            if (!PACKET_get_bytes(&local_ext, &etick, size)) {
-                /* Shouldn't ever happen */
-                retv = -1;
-                goto end;
-            }
-            r = tls_decrypt_ticket(s, etick, size, PACKET_data(session_id),
-                                   PACKET_remaining(session_id), ret);
-            switch (r) {
-            case 2:            /* ticket couldn't be decrypted */
-                s->tlsext_ticket_expected = 1;
-                retv = 2;
-                break;
-            case 3:            /* ticket was decrypted */
-                retv = r;
-                break;
-            case 4:            /* ticket decrypted but need to renew */
-                s->tlsext_ticket_expected = 1;
-                retv = 3;
-                break;
-            default:           /* fatal error */
-                retv = -1;
-                break;
-            }
-            continue;
-        } else {
-            if (type == TLSEXT_TYPE_extended_master_secret)
-                s->s3->flags |= TLS1_FLAGS_RECEIVED_EXTMS;
-            if (!PACKET_forward(&local_ext, size)) {
-                retv = -1;
-                goto end;
-            }
-        }
+    default:           /* fatal error */
+        return -1;
     }
-    if (have_ticket == 0)
-        retv = 0;
- end:
-    return retv;
+}
+
+/*
+ * Sets the extended master secret flag if the extension is present in the
+ * ClientHello and we can support it
+ * Returns:
+ *  1 on success
+ *  0 on error
+ */
+int tls_check_client_ems_support(SSL *s, const CLIENTHELLO_MSG *hello)
+{
+    RAW_EXTENSION *emsext;
+
+    s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
+
+    if (!SSL_IS_DTLS(s) && (s->version < TLS1_VERSION
+                            || s->version > TLS1_2_VERSION))
+        return 1;
+
+    emsext = tls_get_extension_by_type(hello->pre_proc_exts,
+                                       hello->num_extensions,
+                                       TLSEXT_TYPE_extended_master_secret);
+
+    /*
+     * No extensions is a success - we have successfully discovered that the
+     * client doesn't support EMS.
+     */
+    if (emsext == NULL)
+        return 1;
+
+    /* The extensions must always be empty */
+    if (PACKET_remaining(&emsext->data) != 0)
+        return 0;
+
+    s->s3->flags |= TLS1_FLAGS_RECEIVED_EXTMS;
+
+    return 1;
 }
 
 /*-
@@ -2947,13 +3284,14 @@ int tls_check_serverhello_tlsext_early(SSL *s, const PACKET *ext,
  *    4: same as 3, but the ticket needs to be renewed.
  */
 static int tls_decrypt_ticket(SSL *s, const unsigned char *etick,
-                              int eticklen, const unsigned char *sess_id,
-                              int sesslen, SSL_SESSION **psess)
+                              size_t eticklen, const unsigned char *sess_id,
+                              size_t sesslen, SSL_SESSION **psess)
 {
     SSL_SESSION *sess;
     unsigned char *sdec;
     const unsigned char *p;
-    int slen, mlen, renew_ticket = 0, ret = -1;
+    int slen, renew_ticket = 0, ret = -1, declen;
+    size_t mlen;
     unsigned char tick_hmac[EVP_MAX_MD_SIZE];
     HMAC_CTX *hctx = NULL;
     EVP_CIPHER_CTX *ctx;
@@ -3002,7 +3340,7 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick,
      * checks on ticket.
      */
     mlen = HMAC_size(hctx);
-    if (mlen < 0) {
+    if (mlen == 0) {
         goto err;
     }
     /* Sanity check ticket length: must exceed keyname + IV + HMAC */
@@ -3027,17 +3365,18 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick,
     p = etick + 16 + EVP_CIPHER_CTX_iv_length(ctx);
     eticklen -= 16 + EVP_CIPHER_CTX_iv_length(ctx);
     sdec = OPENSSL_malloc(eticklen);
-    if (sdec == NULL || EVP_DecryptUpdate(ctx, sdec, &slen, p, eticklen) <= 0) {
+    if (sdec == NULL || EVP_DecryptUpdate(ctx, sdec, &slen, p,
+                                          (int)eticklen) <= 0) {
         EVP_CIPHER_CTX_free(ctx);
         OPENSSL_free(sdec);
         return -1;
     }
-    if (EVP_DecryptFinal(ctx, sdec + slen, &mlen) <= 0) {
+    if (EVP_DecryptFinal(ctx, sdec + slen, &declen) <= 0) {
         EVP_CIPHER_CTX_free(ctx);
         OPENSSL_free(sdec);
         return 2;
     }
-    slen += mlen;
+    slen += declen;
     EVP_CIPHER_CTX_free(ctx);
     ctx = NULL;
     p = sdec;
@@ -3119,10 +3458,11 @@ static int tls12_find_nid(int id, const tls12_lookup *table, size_t tlen)
     return NID_undef;
 }
 
-int tls12_get_sigandhash(unsigned char *p, const EVP_PKEY *pk, const EVP_MD *md)
+int tls12_get_sigandhash(WPACKET *pkt, const EVP_PKEY *pk, const EVP_MD *md)
 {
     int sig_id, md_id;
-    if (!md)
+
+    if (md == NULL)
         return 0;
     md_id = tls12_find_id(EVP_MD_type(md), tls12_md, OSSL_NELEM(tls12_md));
     if (md_id == -1)
@@ -3130,8 +3470,9 @@ int tls12_get_sigandhash(unsigned char *p, const EVP_PKEY *pk, const EVP_MD *md)
     sig_id = tls12_get_sigid(pk);
     if (sig_id == -1)
         return 0;
-    p[0] = (unsigned char)md_id;
-    p[1] = (unsigned char)sig_id;
+    if (!WPACKET_put_bytes_u8(pkt, md_id) || !WPACKET_put_bytes_u8(pkt, sig_id))
+        return 0;
+
     return 1;
 }
 
@@ -3300,26 +3641,6 @@ void ssl_set_sig_mask(uint32_t *pmask_a, SSL *s, int op)
         *pmask_a |= SSL_aECDSA;
 }
 
-/*
- * Old version of the tls12_copy_sigalgs function used by code that has not
- * yet been converted to WPACKET yet. It will be deleted once WPACKET conversion
- * is complete.
- * TODO - DELETE ME
- */
-size_t tls12_copy_sigalgs_old(SSL *s, unsigned char *out,
-                          const unsigned char *psig, size_t psiglen)
-{
-    unsigned char *tmpout = out;
-    size_t i;
-    for (i = 0; i < psiglen; i += 2, psig += 2) {
-        if (tls12_sigalg_allowed(s, SSL_SECOP_SIGALG_SUPPORTED, psig)) {
-            *tmpout++ = psig[0];
-            *tmpout++ = psig[1];
-        }
-    }
-    return tmpout - out;
-}
-
 int tls12_copy_sigalgs(SSL *s, WPACKET *pkt,
                        const unsigned char *psig, size_t psiglen)
 {
@@ -3327,8 +3648,8 @@ int tls12_copy_sigalgs(SSL *s, WPACKET *pkt,
 
     for (i = 0; i < psiglen; i += 2, psig += 2) {
         if (tls12_sigalg_allowed(s, SSL_SECOP_SIGALG_SUPPORTED, psig)) {
-            if (!WPACKET_put_bytes(pkt, psig[0], 1)
-                    || !WPACKET_put_bytes(pkt, psig[1], 1))
+            if (!WPACKET_put_bytes_u8(pkt, psig[0])
+                    || !WPACKET_put_bytes_u8(pkt, psig[1]))
                 return 0;
         }
     }
@@ -3336,9 +3657,9 @@ int tls12_copy_sigalgs(SSL *s, WPACKET *pkt,
 }
 
 /* Given preference and allowed sigalgs set shared sigalgs */
-static int tls12_shared_sigalgs(SSL *s, TLS_SIGALGS *shsig,
-                                const unsigned char *pref, size_t preflen,
-                                const unsigned char *allow, size_t allowlen)
+static size_t tls12_shared_sigalgs(SSL *s, TLS_SIGALGS *shsig,
+                                   const unsigned char *pref, size_t preflen,
+                                   const unsigned char *allow, size_t allowlen)
 {
     const unsigned char *ptmp, *atmp;
     size_t i, j, nmatch = 0;
@@ -3413,7 +3734,7 @@ static int tls1_set_shared_sigalgs(SSL *s)
 
 /* Set preferred digest for each key type */
 
-int tls1_save_sigalgs(SSL *s, const unsigned char *data, int dsize)
+int tls1_save_sigalgs(SSL *s, const unsigned char *data, size_t dsize)
 {
     CERT *c = s->cert;
     /* Extension ignored for inappropriate versions */
@@ -3500,7 +3821,8 @@ int SSL_get_sigalgs(SSL *s, int idx,
                     unsigned char *rsig, unsigned char *rhash)
 {
     const unsigned char *psig = s->s3->tmp.peer_sigalgs;
-    if (psig == NULL)
+    size_t numsigalgs = s->s3->tmp.peer_sigalgslen / 2;
+    if (psig == NULL || numsigalgs > INT_MAX)
         return 0;
     if (idx >= 0) {
         idx <<= 1;
@@ -3513,7 +3835,7 @@ int SSL_get_sigalgs(SSL *s, int idx,
             *rsig = psig[1];
         tls1_lookup_sigalg(phash, psign, psignhash, psig);
     }
-    return s->s3->tmp.peer_sigalgslen / 2;
+    return (int)numsigalgs;
 }
 
 int SSL_get_shared_sigalgs(SSL *s, int idx,
@@ -3521,7 +3843,8 @@ int SSL_get_shared_sigalgs(SSL *s, int idx,
                            unsigned char *rsig, unsigned char *rhash)
 {
     TLS_SIGALGS *shsigalgs = s->cert->shared_sigalgs;
-    if (!shsigalgs || idx >= (int)s->cert->shared_sigalgslen)
+    if (!shsigalgs || idx >= (int)s->cert->shared_sigalgslen
+            || s->cert->shared_sigalgslen > INT_MAX)
         return 0;
     shsigalgs += idx;
     if (phash)
@@ -3534,7 +3857,7 @@ int SSL_get_shared_sigalgs(SSL *s, int idx,
         *rsig = shsigalgs->rsign;
     if (rhash)
         *rhash = shsigalgs->rhash;
-    return s->cert->shared_sigalgslen;
+    return (int)s->cert->shared_sigalgslen;
 }
 
 #define MAX_SIGALGLEN   (TLSEXT_hash_num * TLSEXT_signature_num * 2)
@@ -3707,7 +4030,7 @@ int tls1_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain,
         /* idx == -2 means checking client certificate chains */
         if (idx == -2) {
             cpk = c->key;
-            idx = cpk - c->pkeys;
+            idx = (int)(cpk - c->pkeys);
         } else
             cpk = c->pkeys + idx;
         pvalid = s->s3->tmp.valid_flags + idx;