Split extensions code into core extensions and server extensions code

Later we will have client extensions code too.

Perl changes reviewed by Richard Levitte. Non-perl changes reviewed by Rich
Salz

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>

4 files changed, 675 insertions, 662 deletions

diff --git a/ssl/build.info b/ssl/build.info
index 931ad61b59..fb2265e145 100644
--- a/ssl/build.info
+++ b/ssl/build.info
@@ -2,7 +2,8 @@ LIBS=../libssl
 SOURCE[../libssl]=\
         pqueue.c packet.c \
         statem/statem_srvr.c statem/statem_clnt.c  s3_lib.c  s3_enc.c record/rec_layer_s3.c \
-        statem/statem_lib.c statem/extensions.c s3_cbc.c s3_msg.c \
+        statem/statem_lib.c statem/extensions.c statem/extensions_srvr.c \
+        s3_cbc.c s3_msg.c \
         methods.c   t1_lib.c  t1_enc.c tls13_enc.c t1_ext.c \
         d1_lib.c  record/rec_layer_d1.c d1_msg.c \
         statem/statem_dtls.c d1_srtp.c \
diff --git a/ssl/statem/extensions.c b/ssl/statem/extensions.c
index c98a2055c2..8bea0746e1 100644
--- a/ssl/statem/extensions.c
+++ b/ssl/statem/extensions.c
@@ -8,33 +8,9 @@
  */
 
 #include <stdlib.h>
-#include <openssl/ocsp.h>
 #include "../ssl_locl.h"
 #include "statem_locl.h"
 
-static int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al);
-static int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, int *al);
-#ifndef OPENSSL_NO_SRP
-static int tls_parse_clienthello_srp(SSL *s, PACKET *pkt, int *al);
-#endif
-#ifndef OPENSSL_NO_EC
-static int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al);
-static int tls_parse_clienthello_supported_groups(SSL *s, PACKET *pkt, int *al);
-#endif
-static int tls_parse_clienthello_session_ticket(SSL *s, PACKET *pkt, int *al);
-static int tls_parse_clienthello_sig_algs(SSL *s, PACKET *pkt, int *al);
-static int tls_parse_clienthello_status_request(SSL *s, PACKET *pkt, int *al);
-#ifndef OPENSSL_NO_NEXTPROTONEG
-static int tls_parse_clienthello_npn(SSL *s, PACKET *pkt, int *al);
-#endif
-static int tls_parse_clienthello_alpn(SSL *s, PACKET *pkt, int *al);
-#ifndef OPENSSL_NO_SRTP
-static int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al);
-#endif
-static int tls_parse_clienthello_etm(SSL *s, PACKET *pkt, int *al);
-static int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al);
-static int tls_parse_clienthello_ems(SSL *s, PACKET *pkt, int *al);
-
 typedef struct {
     /* The ID for the extension */
     unsigned int type;
@@ -535,640 +511,3 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
 
     return 1;
 }
-
-/*
- * Parse the client's renegotiation binding and abort if it's not right
- */
-static int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
-{
-    unsigned int ilen;
-    const unsigned char *data;
-
-    /* Parse the length byte */
-    if (!PACKET_get_1(pkt, &ilen)
-        || !PACKET_get_bytes(pkt, &data, ilen)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_ENCODING_ERR);
-        *al = SSL_AD_ILLEGAL_PARAMETER;
-        return 0;
-    }
-
-    /* Check that the extension matches */
-    if (ilen != s->s3->previous_client_finished_len) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_MISMATCH);
-        *al = SSL_AD_HANDSHAKE_FAILURE;
-        return 0;
-    }
-
-    if (memcmp(data, s->s3->previous_client_finished,
-               s->s3->previous_client_finished_len)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
-               SSL_R_RENEGOTIATION_MISMATCH);
-        *al = SSL_AD_HANDSHAKE_FAILURE;
-        return 0;
-    }
-
-    s->s3->send_connection_binding = 1;
-
-    return 1;
-}
-
-static int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, 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) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    /*
-     * 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
-     * such.
-     * RFC 6066 corrected the mistake but adding new name types
-     * is nevertheless no longer feasible, so act as if no other
-     * SNI types can exist, to simplify parsing.
-     *
-     * Also note that the RFC permits only one SNI value per type,
-     * i.e., we can only have a single hostname.
-     */
-    if (!PACKET_get_1(&sni, &servname_type)
-        || servname_type != TLSEXT_NAMETYPE_host_name
-        || !PACKET_as_length_prefixed_2(&sni, &hostname)) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    if (!s->hit) {
-        if (PACKET_remaining(&hostname) > TLSEXT_MAXLEN_host_name) {
-            *al = TLS1_AD_UNRECOGNIZED_NAME;
-            return 0;
-        }
-
-        if (PACKET_contains_zero_byte(&hostname)) {
-            *al = TLS1_AD_UNRECOGNIZED_NAME;
-            return 0;
-        }
-
-        if (!PACKET_strndup(&hostname, &s->session->tlsext_hostname)) {
-            *al = TLS1_AD_INTERNAL_ERROR;
-            return 0;
-        }
-
-        s->servername_done = 1;
-    } else {
-        /*
-         * 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));
-    }
-
-    return 1;
-}
-
-#ifndef OPENSSL_NO_SRP
-static int tls_parse_clienthello_srp(SSL *s, PACKET *pkt, int *al)
-{
-    PACKET srp_I;
-
-    if (!PACKET_as_length_prefixed_1(pkt, &srp_I)
-            || PACKET_contains_zero_byte(&srp_I)) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    /*
-     * TODO(openssl-team): currently, we re-authenticate the user
-     * upon resumption. Instead, we MUST ignore the login.
-     */
-    if (!PACKET_strndup(&srp_I, &s->srp_ctx.login)) {
-        *al = TLS1_AD_INTERNAL_ERROR;
-        return 0;
-    }
-
-    return 1;
-}
-#endif
-
-#ifndef OPENSSL_NO_EC
-static int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
-{
-    PACKET ec_point_format_list;
-
-    if (!PACKET_as_length_prefixed_1(pkt, &ec_point_format_list)
-        || PACKET_remaining(&ec_point_format_list) == 0) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    if (!s->hit) {
-        if (!PACKET_memdup(&ec_point_format_list,
-                           &s->session->tlsext_ecpointformatlist,
-                           &s->session->tlsext_ecpointformatlist_length)) {
-            *al = TLS1_AD_INTERNAL_ERROR;
-            return 0;
-        }
-    }
-
-    return 1;
-}
-#endif                          /* OPENSSL_NO_EC */
-
-static int tls_parse_clienthello_session_ticket(SSL *s, PACKET *pkt, 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)) {
-        *al = TLS1_AD_INTERNAL_ERROR;
-        return 0;
-    }
-
-    return 1;
-}
-
-static int tls_parse_clienthello_sig_algs(SSL *s, PACKET *pkt, 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;
-        return 0;
-    }
-
-    return 1;
-}
-
-static int tls_parse_clienthello_status_request(SSL *s, PACKET *pkt, int *al)
-{
-    if (!PACKET_get_1(pkt, (unsigned int *)&s->tlsext_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;
-        }
-
-        /*
-         * 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;
-            const unsigned char *id_data;
-
-            if (!PACKET_get_length_prefixed_2(&responder_id_list,
-                                              &responder_id)
-                    || PACKET_remaining(&responder_id) == 0) {
-                *al = SSL_AD_DECODE_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;
-            }
-
-            if (id_data != PACKET_end(&responder_id)) {
-                OCSP_RESPID_free(id);
-                *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;
-            }
-        }
-
-        /* Read in request_extensions */
-        if (!PACKET_as_length_prefixed_2(pkt, &exts)) {
-            *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;
-            }
-        }
-    } else
-#endif
-    {
-        /*
-         * We don't know what to do with any other type so ignore it.
-         */
-        s->tlsext_status_type = -1;
-    }
-
-    return 1;
-}
-
-#ifndef OPENSSL_NO_NEXTPROTONEG
-static int tls_parse_clienthello_npn(SSL *s, PACKET *pkt, 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;
-    }
-
-    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.
- */
-static int tls_parse_clienthello_alpn(SSL *s, PACKET *pkt, int *al)
-{
-    PACKET protocol_list, save_protocol_list, protocol;
-
-    if (s->s3->tmp.finish_md_len != 0)
-        return 1;
-
-    if (!PACKET_as_length_prefixed_2(pkt, &protocol_list)
-        || PACKET_remaining(&protocol_list) < 2) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    save_protocol_list = protocol_list;
-    do {
-        /* Protocol names can't be empty. */
-        if (!PACKET_get_length_prefixed_1(&protocol_list, &protocol)
-                || PACKET_remaining(&protocol) == 0) {
-            *al = SSL_AD_DECODE_ERROR;
-            return 0;
-        }
-    } while (PACKET_remaining(&protocol_list) != 0);
-
-    if (!PACKET_memdup(&save_protocol_list,
-                       &s->s3->alpn_proposed, &s->s3->alpn_proposed_len)) {
-        *al = TLS1_AD_INTERNAL_ERROR;
-        return 0;
-    }
-
-    return 1;
-}
-
-#ifndef OPENSSL_NO_SRTP
-static int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al)
-{
-    SRTP_PROTECTION_PROFILE *sprof;
-    STACK_OF(SRTP_PROTECTION_PROFILE) *srvr;
-    unsigned int ct, mki_len, id;
-    int i, srtp_pref;
-    PACKET subpkt;
-
-    /* Ignore this if we have no SRTP profiles */
-    if (SSL_get_srtp_profiles(s) == NULL)
-        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,
-               SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    srvr = SSL_get_srtp_profiles(s);
-    s->srtp_profile = NULL;
-    /* Search all profiles for a match initially */
-    srtp_pref = sk_SRTP_PROTECTION_PROFILE_num(srvr);
-
-    while (PACKET_remaining(&subpkt)) {
-        if (!PACKET_get_net_2(&subpkt, &id)) {
-            SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_USE_SRTP,
-                   SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-            *al = SSL_AD_DECODE_ERROR;
-            return 0;
-        }
-
-        /*
-         * Only look for match in profiles of higher preference than
-         * current match.
-         * If no profiles have been have been configured then this
-         * does nothing.
-         */
-        for (i = 0; i < srtp_pref; i++) {
-            sprof = sk_SRTP_PROTECTION_PROFILE_value(srvr, i);
-            if (sprof->id == id) {
-                s->srtp_profile = sprof;
-                srtp_pref = i;
-                break;
-            }
-        }
-    }
-
-    /*
-     * 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,
-               SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    if (!PACKET_forward(pkt, mki_len)
-        || PACKET_remaining(pkt)) {
-        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_USE_SRTP, SSL_R_BAD_SRTP_MKI_VALUE);
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    return 1;
-}
-#endif
-
-static int tls_parse_clienthello_etm(SSL *s, PACKET *pkt, int *al)
-{
-    if (!(s->options & SSL_OP_NO_ENCRYPT_THEN_MAC))
-        s->s3->flags |= TLS1_FLAGS_ENCRYPT_THEN_MAC;
-
-    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 tls_parse_clienthello_key_share(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;
-
-    if (s->hit)
-        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);
-        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);
-        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);
-        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_TLS_PARSE_CLIENTHELLO_KEY_SHARE, 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_TLS_PARSE_CLIENTHELLO_KEY_SHARE,
-                   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_TLS_PARSE_CLIENTHELLO_KEY_SHARE, 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_TLS_PARSE_CLIENTHELLO_KEY_SHARE,
-                   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_TLS_PARSE_CLIENTHELLO_KEY_SHARE, 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_TLS_PARSE_CLIENTHELLO_KEY_SHARE, 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_TLS_PARSE_CLIENTHELLO_KEY_SHARE, SSL_R_BAD_ECPOINT);
-            return 0;
-        }
-
-        found = 1;
-    }
-
-    return 1;
-}
-
-#ifndef OPENSSL_NO_EC
-static int tls_parse_clienthello_supported_groups(SSL *s, PACKET *pkt, int *al)
-{
-    PACKET supported_groups_list;
-
-    /* Each group is 2 bytes and we must have at least 1. */
-    if (!PACKET_as_length_prefixed_2(pkt, &supported_groups_list)
-            || PACKET_remaining(&supported_groups_list) == 0
-            || (PACKET_remaining(&supported_groups_list) % 2) != 0) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    if (!s->hit
-            && !PACKET_memdup(&supported_groups_list,
-                              &s->session->tlsext_supportedgroupslist,
-                              &s->session->tlsext_supportedgroupslist_length)) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    return 1;
-}
-#endif
-
-static int tls_parse_clienthello_ems(SSL *s, PACKET *pkt, int *al)
-{
-    /* The extension must always be empty */
-    if (PACKET_remaining(pkt) != 0) {
-        *al = SSL_AD_DECODE_ERROR;
-        return 0;
-    }
-
-    s->s3->flags |= TLS1_FLAGS_RECEIVED_EXTMS;
-
-    return 1;
-}
diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c
new file mode 100644
index 0000000000..38a6bef862
--- /dev/null
+++ b/ssl/statem/extensions_srvr.c
@@ -0,0 +1,649 @@
+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/ocsp.h>
+#include "../ssl_locl.h"
+#include "statem_locl.h"
+
+/*
+ * Parse the client's renegotiation binding and abort if it's not right
+ */
+int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al)
+{
+    unsigned int ilen;
+    const unsigned char *data;
+
+    /* Parse the length byte */
+    if (!PACKET_get_1(pkt, &ilen)
+        || !PACKET_get_bytes(pkt, &data, ilen)) {
+        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
+               SSL_R_RENEGOTIATION_ENCODING_ERR);
+        *al = SSL_AD_ILLEGAL_PARAMETER;
+        return 0;
+    }
+
+    /* Check that the extension matches */
+    if (ilen != s->s3->previous_client_finished_len) {
+        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
+               SSL_R_RENEGOTIATION_MISMATCH);
+        *al = SSL_AD_HANDSHAKE_FAILURE;
+        return 0;
+    }
+
+    if (memcmp(data, s->s3->previous_client_finished,
+               s->s3->previous_client_finished_len)) {
+        SSLerr(SSL_F_TLS_PARSE_CLIENTHELLO_RENEGOTIATE,
+               SSL_R_RENEGOTIATION_MISMATCH);
+        *al = SSL_AD_HANDSHAKE_FAILURE;
+        return 0;
+    }
+
+    s->s3->send_connection_binding = 1;
+
+    return 1;
+}
+
+int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, 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) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    /*
+     * 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
+     * such.
+     * RFC 6066 corrected the mistake but adding new name types
+     * is nevertheless no longer feasible, so act as if no other
+     * SNI types can exist, to simplify parsing.
+     *
+     * Also note that the RFC permits only one SNI value per type,
+     * i.e., we can only have a single hostname.
+     */
+    if (!PACKET_get_1(&sni, &servname_type)
+        || servname_type != TLSEXT_NAMETYPE_host_name
+        || !PACKET_as_length_prefixed_2(&sni, &hostname)) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    if (!s->hit) {
+        if (PACKET_remaining(&hostname) > TLSEXT_MAXLEN_host_name) {
+            *al = TLS1_AD_UNRECOGNIZED_NAME;
+            return 0;
+        }
+
+        if (PACKET_contains_zero_byte(&hostname)) {
+            *al = TLS1_AD_UNRECOGNIZED_NAME;
+            return 0;
+        }
+
+        if (!PACKET_strndup(&hostname, &s->session->tlsext_hostname)) {
+            *al = TLS1_AD_INTERNAL_ERROR;
+            return 0;
+        }
+
+        s->servername_done = 1;
+    } else {
+        /*
+         * 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));
+    }
+
+    return 1;
+}
+
+#ifndef OPENSSL_NO_SRP
+int tls_parse_clienthello_srp(SSL *s, PACKET *pkt, int *al)
+{
+    PACKET srp_I;
+
+    if (!PACKET_as_length_prefixed_1(pkt, &srp_I)
+            || PACKET_contains_zero_byte(&srp_I)) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    /*
+     * TODO(openssl-team): currently, we re-authenticate the user
+     * upon resumption. Instead, we MUST ignore the login.
+     */
+    if (!PACKET_strndup(&srp_I, &s->srp_ctx.login)) {
+        *al = TLS1_AD_INTERNAL_ERROR;
+        return 0;
+    }
+
+    return 1;
+}
+#endif
+
+#ifndef OPENSSL_NO_EC
+int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
+{
+    PACKET ec_point_format_list;
+
+    if (!PACKET_as_length_prefixed_1(pkt, &ec_point_format_list)
+        || PACKET_remaining(&ec_point_format_list) == 0) {
+        *al = SSL_AD_DECODE_ERROR;
+        return 0;
+    }
+
+    if (!s->hit) {
+        if (!PACKET_memdup(&ec_point_format_list,
+                           &s->session->tlsext_ecpointformatlist,
+                           &s->session->tlsext_ecpointformatlist_length)) {
+            *al = TLS1_AD_INTERNAL_ERROR;
+            return 0;
+        }
+    }
+
+    return 1;
+}
+#endif                          /* OPENSSL_NO_EC */
+
+int tls_parse_clienthello_session_ticket(SSL *s, PACKET *pkt, 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)) {
+        *al = TLS1_AD_INTERNAL_ERROR;
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_parse_clienthello_sig_algs(SSL *s, PACKET *pkt, 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;
+        return 0;
+    }
+
+    return 1;
+}
+
+int tls_parse_clienthello_status_request(SSL *s, PACKET *pkt, int *al)
+{
+    if (!PACKET_get_1(pkt, (unsigned int *)&s->tlsext_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;
+        }
+
+        /*
+         * 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;
+            const unsigned char *id_data;
+
+            if (!PACKET_get_length_prefixed_2(&responder_id_list,
+                                              &responder_id)
+                    || PACKET_remaining(&responder_id) == 0) {
+                *al = SSL_AD_DECODE_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;
+            }
+
+            if (id_data != PACKET_end(&responder_id)) {
+                OCSP_RESPID_free(id);
+                *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;
+            }
+        }
+
+        /* Read in request_extensions */
+        if (!PACKET_as_length_prefixed_2(pkt, &exts)) {
+            *al = SSL_AD_DECODE_ERROR;