Retain SSLv2 methods as functions that return NULL

[openssl.git] / ssl / t1_lib.c

/* ssl/t1_lib.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */
/* ====================================================================
 * Copyright (c) 1998-2007 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include <openssl/objects.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/ocsp.h>
#include <openssl/rand.h>
#include "ssl_locl.h"

const char tls1_version_str[] = "TLSv1" OPENSSL_VERSION_PTEXT;

#ifndef OPENSSL_NO_TLSEXT
static int tls_decrypt_ticket(SSL *s, const unsigned char *tick, int ticklen,
                              const unsigned char *sess_id, int sesslen,
                              SSL_SESSION **psess);
#endif

SSL3_ENC_METHOD TLSv1_enc_data = {
    tls1_enc,
    tls1_mac,
    tls1_setup_key_block,
    tls1_generate_master_secret,
    tls1_change_cipher_state,
    tls1_final_finish_mac,
    TLS1_FINISH_MAC_LENGTH,
    tls1_cert_verify_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,
};

long tls1_default_timeout(void)
{
    /*
     * 2 hours, the 24 hours mentioned in the TLSv1 spec is way too long for
     * http, the cache would over fill
     */
    return (60 * 60 * 2);
}

int tls1_new(SSL *s)
{
    if (!ssl3_new(s))
        return (0);
    s->method->ssl_clear(s);
    return (1);
}

void tls1_free(SSL *s)
{
#ifndef OPENSSL_NO_TLSEXT
    if (s->tlsext_session_ticket) {
        OPENSSL_free(s->tlsext_session_ticket);
    }
#endif                          /* OPENSSL_NO_TLSEXT */
    ssl3_free(s);
}

void tls1_clear(SSL *s)
{
    ssl3_clear(s);
    s->version = s->method->version;
}

#ifndef OPENSSL_NO_EC

static int nid_list[] = {
    NID_sect163k1,              /* sect163k1 (1) */
    NID_sect163r1,              /* sect163r1 (2) */
    NID_sect163r2,              /* sect163r2 (3) */
    NID_sect193r1,              /* sect193r1 (4) */
    NID_sect193r2,              /* sect193r2 (5) */
    NID_sect233k1,              /* sect233k1 (6) */
    NID_sect233r1,              /* sect233r1 (7) */
    NID_sect239k1,              /* sect239k1 (8) */
    NID_sect283k1,              /* sect283k1 (9) */
    NID_sect283r1,              /* sect283r1 (10) */
    NID_sect409k1,              /* sect409k1 (11) */
    NID_sect409r1,              /* sect409r1 (12) */
    NID_sect571k1,              /* sect571k1 (13) */
    NID_sect571r1,              /* sect571r1 (14) */
    NID_secp160k1,              /* secp160k1 (15) */
    NID_secp160r1,              /* secp160r1 (16) */
    NID_secp160r2,              /* secp160r2 (17) */
    NID_secp192k1,              /* secp192k1 (18) */
    NID_X9_62_prime192v1,       /* secp192r1 (19) */
    NID_secp224k1,              /* secp224k1 (20) */
    NID_secp224r1,              /* secp224r1 (21) */
    NID_secp256k1,              /* secp256k1 (22) */
    NID_X9_62_prime256v1,       /* secp256r1 (23) */
    NID_secp384r1,              /* secp384r1 (24) */
    NID_secp521r1               /* secp521r1 (25) */
};

static int pref_list[] = {
# ifndef OPENSSL_NO_EC2M
    NID_sect571r1,              /* sect571r1 (14) */
    NID_sect571k1,              /* sect571k1 (13) */
# endif
    NID_secp521r1,              /* secp521r1 (25) */
# ifndef OPENSSL_NO_EC2M
    NID_sect409k1,              /* sect409k1 (11) */
    NID_sect409r1,              /* sect409r1 (12) */
# endif
    NID_secp384r1,              /* secp384r1 (24) */
# ifndef OPENSSL_NO_EC2M
    NID_sect283k1,              /* sect283k1 (9) */
    NID_sect283r1,              /* sect283r1 (10) */
# endif
    NID_secp256k1,              /* secp256k1 (22) */
    NID_X9_62_prime256v1,       /* secp256r1 (23) */
# ifndef OPENSSL_NO_EC2M
    NID_sect239k1,              /* sect239k1 (8) */
    NID_sect233k1,              /* sect233k1 (6) */
    NID_sect233r1,              /* sect233r1 (7) */
# endif
    NID_secp224k1,              /* secp224k1 (20) */
    NID_secp224r1,              /* secp224r1 (21) */
# ifndef OPENSSL_NO_EC2M
    NID_sect193r1,              /* sect193r1 (4) */
    NID_sect193r2,              /* sect193r2 (5) */
# endif
    NID_secp192k1,              /* secp192k1 (18) */
    NID_X9_62_prime192v1,       /* secp192r1 (19) */
# ifndef OPENSSL_NO_EC2M
    NID_sect163k1,              /* sect163k1 (1) */
    NID_sect163r1,              /* sect163r1 (2) */
    NID_sect163r2,              /* sect163r2 (3) */
# endif
    NID_secp160k1,              /* secp160k1 (15) */
    NID_secp160r1,              /* secp160r1 (16) */
    NID_secp160r2,              /* secp160r2 (17) */
};

int tls1_ec_curve_id2nid(int curve_id)
{
    /* ECC curves from RFC 4492 */
    if ((curve_id < 1) || ((unsigned int)curve_id >
                           sizeof(nid_list) / sizeof(nid_list[0])))
        return 0;
    return nid_list[curve_id - 1];
}

int tls1_ec_nid2curve_id(int nid)
{
    /* ECC curves from RFC 4492 */
    switch (nid) {
    case NID_sect163k1:        /* sect163k1 (1) */
        return 1;
    case NID_sect163r1:        /* sect163r1 (2) */
        return 2;
    case NID_sect163r2:        /* sect163r2 (3) */
        return 3;
    case NID_sect193r1:        /* sect193r1 (4) */
        return 4;
    case NID_sect193r2:        /* sect193r2 (5) */
        return 5;
    case NID_sect233k1:        /* sect233k1 (6) */
        return 6;
    case NID_sect233r1:        /* sect233r1 (7) */
        return 7;
    case NID_sect239k1:        /* sect239k1 (8) */
        return 8;
    case NID_sect283k1:        /* sect283k1 (9) */
        return 9;
    case NID_sect283r1:        /* sect283r1 (10) */
        return 10;
    case NID_sect409k1:        /* sect409k1 (11) */
        return 11;
    case NID_sect409r1:        /* sect409r1 (12) */
        return 12;
    case NID_sect571k1:        /* sect571k1 (13) */
        return 13;
    case NID_sect571r1:        /* sect571r1 (14) */
        return 14;
    case NID_secp160k1:        /* secp160k1 (15) */
        return 15;
    case NID_secp160r1:        /* secp160r1 (16) */
        return 16;
    case NID_secp160r2:        /* secp160r2 (17) */
        return 17;
    case NID_secp192k1:        /* secp192k1 (18) */
        return 18;
    case NID_X9_62_prime192v1: /* secp192r1 (19) */
        return 19;
    case NID_secp224k1:        /* secp224k1 (20) */
        return 20;
    case NID_secp224r1:        /* secp224r1 (21) */
        return 21;
    case NID_secp256k1:        /* secp256k1 (22) */
        return 22;
    case NID_X9_62_prime256v1: /* secp256r1 (23) */
        return 23;
    case NID_secp384r1:        /* secp384r1 (24) */
        return 24;
    case NID_secp521r1:        /* secp521r1 (25) */
        return 25;
    default:
        return 0;
    }
}
#endif                          /* OPENSSL_NO_EC */

#ifndef OPENSSL_NO_TLSEXT

/*
 * List of supported signature algorithms and hashes. Should make this
 * customisable at some point, for now include everything we support.
 */

# ifdef OPENSSL_NO_RSA
#  define tlsext_sigalg_rsa(md) /* */
# else
#  define tlsext_sigalg_rsa(md) md, TLSEXT_signature_rsa,
# endif

# ifdef OPENSSL_NO_DSA
#  define tlsext_sigalg_dsa(md) /* */
# else
#  define tlsext_sigalg_dsa(md) md, TLSEXT_signature_dsa,
# endif

# ifdef OPENSSL_NO_ECDSA
#  define tlsext_sigalg_ecdsa(md)
                                /* */
# else
#  define tlsext_sigalg_ecdsa(md) md, TLSEXT_signature_ecdsa,
# endif

# define tlsext_sigalg(md) \
                tlsext_sigalg_rsa(md) \
                tlsext_sigalg_dsa(md) \
                tlsext_sigalg_ecdsa(md)

static unsigned char tls12_sigalgs[] = {
# ifndef OPENSSL_NO_SHA512
    tlsext_sigalg(TLSEXT_hash_sha512)
        tlsext_sigalg(TLSEXT_hash_sha384)
# endif
# ifndef OPENSSL_NO_SHA256
        tlsext_sigalg(TLSEXT_hash_sha256)
        tlsext_sigalg(TLSEXT_hash_sha224)
# endif
# ifndef OPENSSL_NO_SHA
        tlsext_sigalg(TLSEXT_hash_sha1)
# endif
};

int tls12_get_req_sig_algs(SSL *s, unsigned char *p)
{
    size_t slen = sizeof(tls12_sigalgs);
    if (p)
        memcpy(p, tls12_sigalgs, slen);
    return (int)slen;
}

unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *buf,
                                          unsigned char *limit)
{
    int extdatalen = 0;
    unsigned char *orig = buf;
    unsigned char *ret = buf;

    /* don't add extensions for SSLv3 unless doing secure renegotiation */
    if (s->client_version == SSL3_VERSION && !s->s3->send_connection_binding)
        return orig;

    ret += 2;

    if (ret >= limit)
        return NULL;            /* this really never occurs, but ... */

    if (s->tlsext_hostname != NULL) {
        /* Add TLS extension servername to the Client Hello message */
        unsigned long size_str;
        long lenmax;

        /*-
         * check for enough space.
         * 4 for the servername type and entension length
         * 2 for servernamelist length
         * 1 for the hostname type
         * 2 for hostname length
         * + hostname length
         */

        if ((lenmax = limit - ret - 9) < 0
            || (size_str =
                strlen(s->tlsext_hostname)) > (unsigned long)lenmax)
            return NULL;

        /* extension type and length */
        s2n(TLSEXT_TYPE_server_name, ret);
        s2n(size_str + 5, ret);

        /* length of servername list */
        s2n(size_str + 3, ret);

        /* hostname type, length and hostname */
        *(ret++) = (unsigned char)TLSEXT_NAMETYPE_host_name;
        s2n(size_str, ret);
        memcpy(ret, s->tlsext_hostname, size_str);
        ret += size_str;
    }

    /* Add RI if renegotiating */
    if (s->renegotiate) {
        int el;

        if (!ssl_add_clienthello_renegotiate_ext(s, 0, &el, 0)) {
            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_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_clienthello_renegotiate_ext(s, ret, &el, el)) {
            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }

        ret += el;
    }
# ifndef OPENSSL_NO_SRP
    /* Add SRP username if there is one */
    if (s->srp_ctx.login != NULL) { /* Add TLS extension SRP username to the
                                     * Client Hello message */

        int login_len = strlen(s->srp_ctx.login);
        if (login_len > 255 || login_len == 0) {
            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }

        /*-
         * check for enough space.
         * 4 for the srp type type and entension length
         * 1 for the srp user identity
         * + srp user identity length
         */
        if ((limit - ret - 5 - login_len) < 0)
            return NULL;

        /* fill in the extension */
        s2n(TLSEXT_TYPE_srp, ret);
        s2n(login_len + 1, ret);
        (*ret++) = (unsigned char)login_len;
        memcpy(ret, s->srp_ctx.login, login_len);
        ret += login_len;
    }
# endif

# ifndef OPENSSL_NO_EC
    if (s->tlsext_ecpointformatlist != NULL) {
        /*
         * Add TLS extension ECPointFormats to the ClientHello message
         */
        long lenmax;

        if ((lenmax = limit - ret - 5) < 0)
            return NULL;
        if (s->tlsext_ecpointformatlist_length > (unsigned long)lenmax)
            return NULL;
        if (s->tlsext_ecpointformatlist_length > 255) {
            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }

        s2n(TLSEXT_TYPE_ec_point_formats, ret);
        s2n(s->tlsext_ecpointformatlist_length + 1, ret);
        *(ret++) = (unsigned char)s->tlsext_ecpointformatlist_length;
        memcpy(ret, s->tlsext_ecpointformatlist,
               s->tlsext_ecpointformatlist_length);
        ret += s->tlsext_ecpointformatlist_length;
    }
    if (s->tlsext_ellipticcurvelist != NULL) {
        /*
         * Add TLS extension EllipticCurves to the ClientHello message
         */
        long lenmax;

        if ((lenmax = limit - ret - 6) < 0)
            return NULL;
        if (s->tlsext_ellipticcurvelist_length > (unsigned long)lenmax)
            return NULL;
        if (s->tlsext_ellipticcurvelist_length > 65532) {
            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }

        s2n(TLSEXT_TYPE_elliptic_curves, ret);
        s2n(s->tlsext_ellipticcurvelist_length + 2, ret);

        s2n(s->tlsext_ellipticcurvelist_length, ret);
        memcpy(ret, s->tlsext_ellipticcurvelist,
               s->tlsext_ellipticcurvelist_length);
        ret += s->tlsext_ellipticcurvelist_length;
    }
# endif                         /* OPENSSL_NO_EC */

    if (!(SSL_get_options(s) & SSL_OP_NO_TICKET)) {
        int ticklen;
        if (!s->new_session && s->session && s->session->tlsext_tick)
            ticklen = s->session->tlsext_ticklen;
        else if (s->session && s->tlsext_session_ticket &&
                 s->tlsext_session_ticket->data) {
            ticklen = s->tlsext_session_ticket->length;
            s->session->tlsext_tick = OPENSSL_malloc(ticklen);
            if (!s->session->tlsext_tick)
                return NULL;
            memcpy(s->session->tlsext_tick,
                   s->tlsext_session_ticket->data, ticklen);
            s->session->tlsext_ticklen = ticklen;
        } else
            ticklen = 0;
        if (ticklen == 0 && s->tlsext_session_ticket &&
            s->tlsext_session_ticket->data == NULL)
            goto skip_ext;
        /*
         * Check for enough room 2 for extension type, 2 for len rest for
         * ticket
         */
        if ((long)(limit - ret - 4 - ticklen) < 0)
            return NULL;
        s2n(TLSEXT_TYPE_session_ticket, ret);
        s2n(ticklen, ret);
        if (ticklen) {
            memcpy(ret, s->session->tlsext_tick, ticklen);
            ret += ticklen;
        }
    }
 skip_ext:

    if (TLS1_get_client_version(s) >= TLS1_2_VERSION) {
        if ((size_t)(limit - ret) < sizeof(tls12_sigalgs) + 6)
            return NULL;
        s2n(TLSEXT_TYPE_signature_algorithms, ret);
        s2n(sizeof(tls12_sigalgs) + 2, ret);
        s2n(sizeof(tls12_sigalgs), ret);
        memcpy(ret, tls12_sigalgs, sizeof(tls12_sigalgs));
        ret += sizeof(tls12_sigalgs);
    }
# ifdef TLSEXT_TYPE_opaque_prf_input
    if (s->s3->client_opaque_prf_input != NULL && s->version != DTLS1_VERSION) {
        size_t col = s->s3->client_opaque_prf_input_len;

        if ((long)(limit - ret - 6 - col < 0))
            return NULL;
        if (col > 0xFFFD)       /* can't happen */
            return NULL;

        s2n(TLSEXT_TYPE_opaque_prf_input, ret);
        s2n(col + 2, ret);
        s2n(col, ret);
        memcpy(ret, s->s3->client_opaque_prf_input, col);
        ret += col;
    }
# endif

    if (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp &&
        s->version != DTLS1_VERSION) {
        int i;
        long extlen, idlen, itmp;
        OCSP_RESPID *id;

        idlen = 0;
        for (i = 0; i < sk_OCSP_RESPID_num(s->tlsext_ocsp_ids); i++) {
            id = sk_OCSP_RESPID_value(s->tlsext_ocsp_ids, i);
            itmp = i2d_OCSP_RESPID(id, NULL);
            if (itmp <= 0)
                return NULL;
            idlen += itmp + 2;
        }

        if (s->tlsext_ocsp_exts) {
            extlen = i2d_X509_EXTENSIONS(s->tlsext_ocsp_exts, NULL);
            if (extlen < 0)
                return NULL;
        } else
            extlen = 0;

        if ((long)(limit - ret - 7 - extlen - idlen) < 0)
            return NULL;
        s2n(TLSEXT_TYPE_status_request, ret);
        if (extlen + idlen > 0xFFF0)
            return NULL;
        s2n(extlen + idlen + 5, ret);
        *(ret++) = TLSEXT_STATUSTYPE_ocsp;
        s2n(idlen, ret);
        for (i = 0; i < sk_OCSP_RESPID_num(s->tlsext_ocsp_ids); i++) {
            /* save position of id len */
            unsigned char *q = ret;
            id = sk_OCSP_RESPID_value(s->tlsext_ocsp_ids, i);
            /* skip over id len */
            ret += 2;
            itmp = i2d_OCSP_RESPID(id, &ret);
            /* write id len */
            s2n(itmp, q);
        }
        s2n(extlen, ret);
        if (extlen > 0)
            i2d_X509_EXTENSIONS(s->tlsext_ocsp_exts, &ret);
    }
# ifndef OPENSSL_NO_HEARTBEATS
    /* Add Heartbeat extension */
    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_TLSEXT_HB_DONT_RECV_REQUESTS)
        *(ret++) = SSL_TLSEXT_HB_DONT_SEND_REQUESTS;
    else
        *(ret++) = SSL_TLSEXT_HB_ENABLED;
# endif

# ifndef OPENSSL_NO_NEXTPROTONEG
    if (s->ctx->next_proto_select_cb && !s->s3->tmp.finish_md_len) {
        /*
         * The client advertises an emtpy extension to indicate its support
         * for Next Protocol Negotiation
         */
        if (limit - ret - 4 < 0)
            return NULL;
        s2n(TLSEXT_TYPE_next_proto_neg, ret);
        s2n(0, ret);
    }
# endif

# ifndef OPENSSL_NO_SRTP
    if (SSL_IS_DTLS(s) && SSL_get_srtp_profiles(s)) {
        int el;

        ssl_add_clienthello_use_srtp_ext(s, 0, &el, 0);

        if ((limit - ret - 4 - el) < 0)
            return NULL;

        s2n(TLSEXT_TYPE_use_srtp, ret);
        s2n(el, ret);

        if (ssl_add_clienthello_use_srtp_ext(s, ret, &el, el)) {
            SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }
        ret += el;
    }
# endif
    /*
     * Add padding to workaround bugs in F5 terminators. See
     * https://tools.ietf.org/html/draft-agl-tls-padding-03 NB: because this
     * code works out the length of all existing extensions it MUST always
     * appear last.
     */
    if (s->options & SSL_OP_TLSEXT_PADDING) {
        int hlen = ret - (unsigned char *)s->init_buf->data;
        /*
         * The code in s23_clnt.c to build ClientHello messages includes the
         * 5-byte record header in the buffer, while the code in s3_clnt.c
         * does not.
         */
        if (s->state == SSL23_ST_CW_CLNT_HELLO_A)
            hlen -= 5;
        if (hlen > 0xff && hlen < 0x200) {
            hlen = 0x200 - hlen;
            if (hlen >= 4)
                hlen -= 4;
            else
                hlen = 0;

            s2n(TLSEXT_TYPE_padding, ret);
            s2n(hlen, ret);
            memset(ret, 0, hlen);
            ret += hlen;
        }
    }

    if ((extdatalen = ret - orig - 2) == 0)
        return orig;

    s2n(extdatalen, orig);
    return ret;
}

unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
                                          unsigned char *limit)
{
    int extdatalen = 0;
    unsigned char *orig = buf;
    unsigned char *ret = buf;
# ifndef OPENSSL_NO_NEXTPROTONEG
    int next_proto_neg_seen;
# endif

    /*
     * don't add extensions for SSLv3, unless doing secure renegotiation
     */
    if (s->version == SSL3_VERSION && !s->s3->send_connection_binding)
        return orig;

    ret += 2;
    if (ret >= limit)
        return NULL;            /* this really never occurs, but ... */

    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);
    }

    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;
        }

        ret += el;
    }
# ifndef OPENSSL_NO_EC
    if (s->tlsext_ecpointformatlist != NULL) {
        /*
         * Add TLS extension ECPointFormats to the ServerHello message
         */
        long lenmax;

        if ((lenmax = limit - ret - 5) < 0)
            return NULL;
        if (s->tlsext_ecpointformatlist_length > (unsigned long)lenmax)
            return NULL;
        if (s->tlsext_ecpointformatlist_length > 255) {
            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }

        s2n(TLSEXT_TYPE_ec_point_formats, ret);
        s2n(s->tlsext_ecpointformatlist_length + 1, ret);
        *(ret++) = (unsigned char)s->tlsext_ecpointformatlist_length;
        memcpy(ret, s->tlsext_ecpointformatlist,
               s->tlsext_ecpointformatlist_length);
        ret += s->tlsext_ecpointformatlist_length;

    }
    /*
     * Currently the server should not respond with a SupportedCurves
     * extension
     */
# endif                         /* OPENSSL_NO_EC */

    if (s->tlsext_ticket_expected && !(SSL_get_options(s) & SSL_OP_NO_TICKET)) {
        if ((long)(limit - ret - 4) < 0)
            return NULL;
        s2n(TLSEXT_TYPE_session_ticket, ret);
        s2n(0, ret);
    }

    if (s->tlsext_status_expected) {
        if ((long)(limit - ret - 4) < 0)
            return NULL;
        s2n(TLSEXT_TYPE_status_request, ret);
        s2n(0, ret);
    }
# ifdef TLSEXT_TYPE_opaque_prf_input
    if (s->s3->server_opaque_prf_input != NULL && s->version != DTLS1_VERSION) {
        size_t sol = s->s3->server_opaque_prf_input_len;

        if ((long)(limit - ret - 6 - sol) < 0)
            return NULL;
        if (sol > 0xFFFD)       /* can't happen */
            return NULL;

        s2n(TLSEXT_TYPE_opaque_prf_input, ret);
        s2n(sol + 2, ret);
        s2n(sol, ret);
        memcpy(ret, s->s3->server_opaque_prf_input, sol);
        ret += sol;
    }
# endif

# ifndef OPENSSL_NO_SRTP
    if (SSL_IS_DTLS(s) && s->srtp_profile) {
        int el;

        ssl_add_serverhello_use_srtp_ext(s, 0, &el, 0);

        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)) {
            SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
            return NULL;
        }
        ret += el;
    }
# endif

    if (((s->s3->tmp.new_cipher->id & 0xFFFF) == 0x80
         || (s->s3->tmp.new_cipher->id & 0xFFFF) == 0x81)
        && (SSL_get_options(s) & SSL_OP_CRYPTOPRO_TLSEXT_BUG)) {
        const unsigned char cryptopro_ext[36] = {
            0xfd, 0xe8,         /* 65000 */
            0x00, 0x20,         /* 32 bytes length */
            0x30, 0x1e, 0x30, 0x08, 0x06, 0x06, 0x2a, 0x85,
            0x03, 0x02, 0x02, 0x09, 0x30, 0x08, 0x06, 0x06,
            0x2a, 0x85, 0x03, 0x02, 0x02, 0x16, 0x30, 0x08,
            0x06, 0x06, 0x2a, 0x85, 0x03, 0x02, 0x02, 0x17
        };
        if (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 (s->tlsext_heartbeat & SSL_TLSEXT_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_TLSEXT_HB_DONT_RECV_REQUESTS)
            *(ret++) = SSL_TLSEXT_HB_DONT_SEND_REQUESTS;
        else
            *(ret++) = SSL_TLSEXT_HB_ENABLED;

    }
# endif

# ifndef OPENSSL_NO_NEXTPROTONEG
    next_proto_neg_seen = s->s3->next_proto_neg_seen;
    s->s3->next_proto_neg_seen = 0;
    if (next_proto_neg_seen && s->ctx->next_protos_advertised_cb) {
        const unsigned char *npa;
        unsigned int npalen;
        int r;

        r = s->ctx->next_protos_advertised_cb(s, &npa, &npalen,
                                              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;
            s->s3->next_proto_neg_seen = 1;
        }
    }
# endif

    if ((extdatalen = ret - orig - 2) == 0)
        return orig;

    s2n(extdatalen, orig);
    return ret;
}

# ifndef OPENSSL_NO_EC
/*-
 * ssl_check_for_safari attempts to fingerprint Safari using OS X
 * SecureTransport using the TLS extension block in |d|, of length |n|.
 * Safari, since 10.6, sends exactly these extensions, in this order:
 *   SNI,
 *   elliptic_curves
 *   ec_point_formats
 *
 * We wish to fingerprint Safari because they broke ECDHE-ECDSA support in 10.8,
 * but they advertise support. So enabling ECDHE-ECDSA ciphers breaks them.
 * 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 unsigned char *data,
                                 const unsigned char *limit)
{
    unsigned short type, size;
    static const unsigned char kSafariExtensionsBlock[] = {
        0x00, 0x0a,             /* elliptic_curves extension */
        0x00, 0x08,             /* 8 bytes */
        0x00, 0x06,             /* 6 bytes of curve ids */
        0x00, 0x17,             /* P-256 */
        0x00, 0x18,             /* P-384 */
        0x00, 0x19,             /* P-521 */

        0x00, 0x0b,             /* ec_point_formats */
        0x00, 0x02,             /* 2 bytes */
        0x01,                   /* 1 point format */
        0x00,                   /* uncompressed */
    };

    /* The following is only present in TLS 1.2 */
    static const unsigned char kSafariTLS12ExtensionsBlock[] = {
        0x00, 0x0d,             /* signature_algorithms */
        0x00, 0x0c,             /* 12 bytes */
        0x00, 0x0a,             /* 10 bytes */
        0x05, 0x01,             /* SHA-384/RSA */
        0x04, 0x01,             /* SHA-256/RSA */
        0x02, 0x01,             /* SHA-1/RSA */
        0x04, 0x03,             /* SHA-256/ECDSA */
        0x02, 0x03,             /* SHA-1/ECDSA */
    };

    if (data >= (limit - 2))
        return;
    data += 2;

    if (data > (limit - 4))
        return;
    n2s(data, type);
    n2s(data, size);

    if (type != TLSEXT_TYPE_server_name)
        return;

    if (data + size > limit)
        return;
    data += size;

    if (TLS1_get_client_version(s) >= TLS1_2_VERSION) {
        const size_t len1 = sizeof(kSafariExtensionsBlock);
        const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock);

        if (data + len1 + len2 != limit)
            return;
        if (memcmp(data, kSafariExtensionsBlock, len1) != 0)
            return;
        if (memcmp(data + len1, kSafariTLS12ExtensionsBlock, len2) != 0)
            return;
    } else {
        const size_t len = sizeof(kSafariExtensionsBlock);

        if (data + len != limit)
            return;
        if (memcmp(data, kSafariExtensionsBlock, len) != 0)
            return;
    }

    s->s3->is_probably_safari = 1;
}
# endif                         /* !OPENSSL_NO_EC */

int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p,
                                 unsigned char *limit, int *al)
{
    unsigned short type;
    unsigned short size;
    unsigned short len;
    unsigned char *data = *p;
    int renegotiate_seen = 0;
    int sigalg_seen = 0;

    s->servername_done = 0;
    s->tlsext_status_type = -1;
# ifndef OPENSSL_NO_NEXTPROTONEG
    s->s3->next_proto_neg_seen = 0;
# endif

# ifndef OPENSSL_NO_HEARTBEATS
    s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
                             SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
# endif

# ifndef OPENSSL_NO_EC
    if (s->options & SSL_OP_SAFARI_ECDHE_ECDSA_BUG)
        ssl_check_for_safari(s, data, limit);
# endif                         /* !OPENSSL_NO_EC */

# ifndef OPENSSL_NO_SRP
    if (s->srp_ctx.login != NULL) {
        OPENSSL_free(s->srp_ctx.login);
        s->srp_ctx.login = NULL;
    }
# endif

    s->srtp_profile = NULL;

    if (data == limit)
        goto ri_check;

    if (data > (limit - 2))
        goto err;

    n2s(data, len);

    if (data + len != limit)
        goto err;

    while (data <= (limit - 4)) {
        n2s(data, type);
        n2s(data, size);

        if (data + size > (limit))
            goto err;
# if 0
        fprintf(stderr, "Received extension type %d size %d\n", type, size);
# endif
        if (s->tlsext_debug_cb)
            s->tlsext_debug_cb(s, 0, type, data, size, s->tlsext_debug_arg);
/*-
 * 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 (type == TLSEXT_TYPE_server_name) {
            unsigned char *sdata;
            int servname_type;
            int dsize;

            if (size < 2)
                goto err;
            n2s(data, dsize);
            size -= 2;
            if (dsize > size)
                goto err;

            sdata = data;
            while (dsize > 3) {
                servname_type = *(sdata++);
                n2s(sdata, len);
                dsize -= 3;

                if (len > dsize)
                    goto err;

                if (s->servername_done == 0)
                    switch (servname_type) {
                    case TLSEXT_NAMETYPE_host_name:
                        if (!s->hit) {
                            if (s->session->tlsext_hostname)
                                goto err;

                            if (len > TLSEXT_MAXLEN_host_name) {
                                *al = TLS1_AD_UNRECOGNIZED_NAME;
                                return 0;
                            }
                            if ((s->session->tlsext_hostname =
                                 OPENSSL_malloc(len + 1)) == NULL) {
                                *al = TLS1_AD_INTERNAL_ERROR;
                                return 0;
                            }
                            memcpy(s->session->tlsext_hostname, sdata, len);
                            s->session->tlsext_hostname[len] = '\0';
                            if (strlen(s->session->tlsext_hostname) != len) {
                                OPENSSL_free(s->session->tlsext_hostname);
                                s->session->tlsext_hostname = NULL;
                                *al = TLS1_AD_UNRECOGNIZED_NAME;
                                return 0;
                            }
                            s->servername_done = 1;

                        } else
                            s->servername_done = s->session->tlsext_hostname
                                && strlen(s->session->tlsext_hostname) == len
                                && strncmp(s->session->tlsext_hostname,
                                           (char *)sdata, len) == 0;

                        break;

                    default:
                        break;
                    }

                dsize -= len;
            }
            if (dsize != 0)
                goto err;

        }
# ifndef OPENSSL_NO_SRP
        else if (type == TLSEXT_TYPE_srp) {
            if (size == 0 || ((len = data[0])) != (size - 1))
                goto err;
            if (s->srp_ctx.login != NULL)
                goto err;
            if ((s->srp_ctx.login = OPENSSL_malloc(len + 1)) == NULL)
                return -1;
            memcpy(s->srp_ctx.login, &data[1], len);
            s->srp_ctx.login[len] = '\0';

            if (strlen(s->srp_ctx.login) != len)
                goto err;
        }
# endif

# ifndef OPENSSL_NO_EC
        else if (type == TLSEXT_TYPE_ec_point_formats) {
            unsigned char *sdata = data;
            int ecpointformatlist_length = *(sdata++);

            if (ecpointformatlist_length != size - 1)
                goto err;
            if (!s->hit) {
                if (s->session->tlsext_ecpointformatlist) {
                    OPENSSL_free(s->session->tlsext_ecpointformatlist);
                    s->session->tlsext_ecpointformatlist = NULL;
                }
                s->session->tlsext_ecpointformatlist_length = 0;
                if ((s->session->tlsext_ecpointformatlist =
                     OPENSSL_malloc(ecpointformatlist_length)) == NULL) {
                    *al = TLS1_AD_INTERNAL_ERROR;
                    return 0;
                }
                s->session->tlsext_ecpointformatlist_length =
                    ecpointformatlist_length;
                memcpy(s->session->tlsext_ecpointformatlist, sdata,
                       ecpointformatlist_length);
            }
#  if 0
            fprintf(stderr,
                    "ssl_parse_clienthello_tlsext s->session->tlsext_ecpointformatlist (length=%i) ",
                    s->session->tlsext_ecpointformatlist_length);
            sdata = s->session->tlsext_ecpointformatlist;
            for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++)
                fprintf(stderr, "%i ", *(sdata++));
            fprintf(stderr, "\n");
#  endif
        } else if (type == TLSEXT_TYPE_elliptic_curves) {
            unsigned char *sdata = data;
            int ellipticcurvelist_length = (*(sdata++) << 8);
            ellipticcurvelist_length += (*(sdata++));

            if (ellipticcurvelist_length != size - 2 ||
                ellipticcurvelist_length < 1 ||
                /* Each NamedCurve is 2 bytes. */
                ellipticcurvelist_length & 1)
                    goto err;

            if (!s->hit) {
                if (s->session->tlsext_ellipticcurvelist)
                    goto err;

                s->session->tlsext_ellipticcurvelist_length = 0;
                if ((s->session->tlsext_ellipticcurvelist =
                     OPENSSL_malloc(ellipticcurvelist_length)) == NULL) {
                    *al = TLS1_AD_INTERNAL_ERROR;
                    return 0;
                }
                s->session->tlsext_ellipticcurvelist_length =
                    ellipticcurvelist_length;
                memcpy(s->session->tlsext_ellipticcurvelist, sdata,
                       ellipticcurvelist_length);
            }
#  if 0
            fprintf(stderr,
                    "ssl_parse_clienthello_tlsext s->session->tlsext_ellipticcurvelist (length=%i) ",
                    s->session->tlsext_ellipticcurvelist_length);
            sdata = s->session->tlsext_ellipticcurvelist;
            for (i = 0; i < s->session->tlsext_ellipticcurvelist_length; i++)
                fprintf(stderr, "%i ", *(sdata++));
            fprintf(stderr, "\n");
#  endif
        }
# endif                         /* OPENSSL_NO_EC */
# ifdef TLSEXT_TYPE_opaque_prf_input
        else if (type == TLSEXT_TYPE_opaque_prf_input &&
                 s->version != DTLS1_VERSION) {
            unsigned char *sdata = data;

            if (size < 2) {
                *al = SSL_AD_DECODE_ERROR;
                return 0;
            }
            n2s(sdata, s->s3->client_opaque_prf_input_len);
            if (s->s3->client_opaque_prf_input_len != size - 2) {
                *al = SSL_AD_DECODE_ERROR;
                return 0;
            }

            if (s->s3->client_opaque_prf_input != NULL) {
                /* shouldn't really happen */
                OPENSSL_free(s->s3->client_opaque_prf_input);
            }

            /* dummy byte just to get non-NULL */
            if (s->s3->client_opaque_prf_input_len == 0)
                s->s3->client_opaque_prf_input = OPENSSL_malloc(1);
            else
                s->s3->client_opaque_prf_input =
                    BUF_memdup(sdata, s->s3->client_opaque_prf_input_len);
            if (s->s3->client_opaque_prf_input == NULL) {
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
        }
# endif
        else if (type == TLSEXT_TYPE_session_ticket) {
            if (s->tls_session_ticket_ext_cb &&
                !s->tls_session_ticket_ext_cb(s, data, size,
                                              s->tls_session_ticket_ext_cb_arg))
            {
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
        } else if (type == TLSEXT_TYPE_renegotiate) {
            if (!ssl_parse_clienthello_renegotiate_ext(s, data, size, al))
                return 0;
            renegotiate_seen = 1;
        } else if (type == TLSEXT_TYPE_signature_algorithms) {
            int dsize;
            if (sigalg_seen || size < 2)
                goto err;
            sigalg_seen = 1;
            n2s(data, dsize);
            size -= 2;
            if (dsize != size || dsize & 1)
                goto err;
            if (!tls1_process_sigalgs(s, data, dsize))
                goto err;
        } else if (type == TLSEXT_TYPE_status_request &&
                   s->version != DTLS1_VERSION) {

            if (size < 5)
                goto err;

            s->tlsext_status_type = *data++;
            size--;
            if (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp) {
                const unsigned char *sdata;
                int dsize;
                /* Read in responder_id_list */
                n2s(data, dsize);
                size -= 2;
                if (dsize > size)
                    goto err;
                while (dsize > 0) {
                    OCSP_RESPID *id;
                    int idsize;
                    if (dsize < 4)
                        goto err;
                    n2s(data, idsize);
                    dsize -= 2 + idsize;
                    size -= 2 + idsize;
                    if (dsize < 0)
                        goto err;
                    sdata = data;
                    data += idsize;
                    id = d2i_OCSP_RESPID(NULL, &sdata, idsize);
                    if (!id)
                        goto err;
                    if (data != sdata) {
                        OCSP_RESPID_free(id);
                        goto err;
                    }
                    if (!s->tlsext_ocsp_ids
                        && !(s->tlsext_ocsp_ids =
                             sk_OCSP_RESPID_new_null())) {
                        OCSP_RESPID_free(id);
                        *al = SSL_AD_INTERNAL_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 (size < 2)
                    goto err;
                n2s(data, dsize);
                size -= 2;
                if (dsize != size)
                    goto err;
                sdata = data;
                if (dsize > 0) {
                    if (s->tlsext_ocsp_exts) {
                        sk_X509_EXTENSION_pop_free(s->tlsext_ocsp_exts,
                                                   X509_EXTENSION_free);
                    }

                    s->tlsext_ocsp_exts =
                        d2i_X509_EXTENSIONS(NULL, &sdata, dsize);
                    if (!s->tlsext_ocsp_exts || (data + dsize != sdata))
                        goto err;
                }
            }
            /*
             * We don't know what to do with any other type * so ignore it.
             */
            else
                s->tlsext_status_type = -1;
        }
# ifndef OPENSSL_NO_HEARTBEATS
        else if (type == TLSEXT_TYPE_heartbeat) {
            switch (data[0]) {
            case 0x01:         /* Client allows us to send HB requests */
                s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                break;
            case 0x02:         /* Client doesn't accept HB requests */
                s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                s->tlsext_heartbeat |= SSL_TLSEXT_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) {
            /*-
             * 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 renegotation 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;
        }
# endif

        /* 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, data, size, al))
                return 0;
        }
# endif

        data += size;
    }

    /* Spurious data on the end */
    if (data != limit)
        goto err;

    *p = data;

 ri_check:

    /* Need RI if renegotiating */

    if (!renegotiate_seen && s->renegotiate &&
        !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
        *al = SSL_AD_HANDSHAKE_FAILURE;
        SSLerr(SSL_F_SSL_PARSE_CLIENTHELLO_TLSEXT,
               SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
        return 0;
    }

    return 1;
err:
    *al = SSL_AD_DECODE_ERROR;
    return 0;
}

# ifndef OPENSSL_NO_NEXTPROTONEG
/*
 * ssl_next_proto_validate validates a Next Protocol Negotiation block. No
 * elements of zero length are allowed and the set of elements must exactly
 * fill the length of the block.
 */
static char ssl_next_proto_validate(unsigned char *d, unsigned len)
{
    unsigned int off = 0;

    while (off < len) {
        if (d[off] == 0)
            return 0;
        off += d[off];
        off++;
    }

    return off == len;
}
# endif

int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
                                 int n, int *al)
{
    unsigned short length;
    unsigned short type;
    unsigned short size;
    unsigned char *data = *p;
    int tlsext_servername = 0;
    int renegotiate_seen = 0;

# ifndef OPENSSL_NO_NEXTPROTONEG
    s->s3->next_proto_neg_seen = 0;
# endif
    s->tlsext_ticket_expected = 0;

# ifndef OPENSSL_NO_HEARTBEATS
    s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
                             SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
# endif

    if (data >= (d + n - 2))
        goto ri_check;

    n2s(data, length);
    if (data + length != d + n) {
        *al = SSL_AD_DECODE_ERROR;
        return 0;
    }

    while (data <= (d + n - 4)) {
        n2s(data, type);
        n2s(data, size);

        if (data + size > (d + n))
            goto ri_check;

        if (s->tlsext_debug_cb)
            s->tlsext_debug_cb(s, 1, type, data, size, s->tlsext_debug_arg);

        if (type == TLSEXT_TYPE_server_name) {
            if (s->tlsext_hostname == NULL || size > 0) {
                *al = TLS1_AD_UNRECOGNIZED_NAME;
                return 0;
            }
            tlsext_servername = 1;
        }
# ifndef OPENSSL_NO_EC
        else if (type == TLSEXT_TYPE_ec_point_formats) {
            unsigned char *sdata = data;
            int ecpointformatlist_length = *(sdata++);

            if (ecpointformatlist_length != size - 1 ||
                ecpointformatlist_length < 1) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
            if (!s->hit) {
                s->session->tlsext_ecpointformatlist_length = 0;
                if (s->session->tlsext_ecpointformatlist != NULL)
                    OPENSSL_free(s->session->tlsext_ecpointformatlist);
                if ((s->session->tlsext_ecpointformatlist =
                     OPENSSL_malloc(ecpointformatlist_length)) == NULL) {
                    *al = TLS1_AD_INTERNAL_ERROR;
                    return 0;
                }
                s->session->tlsext_ecpointformatlist_length =
                    ecpointformatlist_length;
                memcpy(s->session->tlsext_ecpointformatlist, sdata,
                       ecpointformatlist_length);
            }
#  if 0
            fprintf(stderr,
                    "ssl_parse_serverhello_tlsext s->session->tlsext_ecpointformatlist ");
            sdata = s->session->tlsext_ecpointformatlist;
            for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++)
                fprintf(stderr, "%i ", *(sdata++));
            fprintf(stderr, "\n");
#  endif
        }
# endif                         /* OPENSSL_NO_EC */

        else if (type == TLSEXT_TYPE_session_ticket) {
            if (s->tls_session_ticket_ext_cb &&
                !s->tls_session_ticket_ext_cb(s, data, size,
                                              s->tls_session_ticket_ext_cb_arg))
            {
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
            if ((SSL_get_options(s) & SSL_OP_NO_TICKET)
                || (size > 0)) {
                *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                return 0;
            }
            s->tlsext_ticket_expected = 1;
        }
# ifdef TLSEXT_TYPE_opaque_prf_input
        else if (type == TLSEXT_TYPE_opaque_prf_input &&
                 s->version != DTLS1_VERSION) {
            unsigned char *sdata = data;

            if (size < 2) {
                *al = SSL_AD_DECODE_ERROR;
                return 0;
            }
            n2s(sdata, s->s3->server_opaque_prf_input_len);
            if (s->s3->server_opaque_prf_input_len != size - 2) {
                *al = SSL_AD_DECODE_ERROR;
                return 0;
            }

            if (s->s3->server_opaque_prf_input != NULL) {
                /* shouldn't really happen */
                OPENSSL_free(s->s3->server_opaque_prf_input);
            }
            if (s->s3->server_opaque_prf_input_len == 0) {
                /* dummy byte just to get non-NULL */
                s->s3->server_opaque_prf_input = OPENSSL_malloc(1);
            } else {
                s->s3->server_opaque_prf_input =
                    BUF_memdup(sdata, s->s3->server_opaque_prf_input_len);
            }

            if (s->s3->server_opaque_prf_input == NULL) {
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
        }
# endif
        else if (type == TLSEXT_TYPE_status_request &&
                 s->version != DTLS1_VERSION) {
            /*
             * MUST be empty and only sent if we've requested a status
             * request message.
             */
            if ((s->tlsext_status_type == -1) || (size > 0)) {
                *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                return 0;
            }
            /* Set flag to expect CertificateStatus message */
            s->tlsext_status_expected = 1;
        }
# ifndef OPENSSL_NO_NEXTPROTONEG
        else if (type == TLSEXT_TYPE_next_proto_neg &&
                 s->s3->tmp.finish_md_len == 0) {
            unsigned char *selected;
            unsigned char selected_len;

            /* We must have requested it. */
            if (s->ctx->next_proto_select_cb == NULL) {
                *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                return 0;
            }
            /* The data must be valid */
            if (!ssl_next_proto_validate(data, size)) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
            if (s->
                ctx->next_proto_select_cb(s, &selected, &selected_len, data,
                                          size,
                                          s->ctx->next_proto_select_cb_arg) !=
                SSL_TLSEXT_ERR_OK) {
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
            s->next_proto_negotiated = OPENSSL_malloc(selected_len);
            if (!s->next_proto_negotiated) {
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
            memcpy(s->next_proto_negotiated, selected, selected_len);
            s->next_proto_negotiated_len = selected_len;
            s->s3->next_proto_neg_seen = 1;
        }
# endif
        else if (type == TLSEXT_TYPE_renegotiate) {
            if (!ssl_parse_serverhello_renegotiate_ext(s, data, size, al))
                return 0;
            renegotiate_seen = 1;
        }
# ifndef OPENSSL_NO_HEARTBEATS
        else if (type == TLSEXT_TYPE_heartbeat) {
            switch (data[0]) {
            case 0x01:         /* Server allows us to send HB requests */
                s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                break;
            case 0x02:         /* Server doesn't accept HB requests */
                s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                s->tlsext_heartbeat |= SSL_TLSEXT_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, data, size, al))
                return 0;
        }
# endif

        data += size;
    }

    if (data != d + n) {
        *al = SSL_AD_DECODE_ERROR;
        return 0;
    }

    if (!s->hit && tlsext_servername == 1) {
        if (s->tlsext_hostname) {
            if (s->session->tlsext_hostname == NULL) {
                s->session->tlsext_hostname = BUF_strdup(s->tlsext_hostname);
                if (!s->session->tlsext_hostname) {
                    *al = SSL_AD_UNRECOGNIZED_NAME;
                    return 0;
                }
            } else {
                *al = SSL_AD_DECODE_ERROR;
                return 0;
            }
        }
    }

    *p = data;

 ri_check:

    /*
     * Determine if we need to see RI. Strictly speaking if we want to avoid
     * an attack we should *always* see RI even on initial server hello
     * because the client doesn't see any renegotiation during an attack.
     * However this would mean we could not connect to any server which
     * doesn't support RI so for the immediate future tolerate RI absence on
     * initial connect only.
     */
    if (!renegotiate_seen && !(s->options & SSL_OP_LEGACY_SERVER_CONNECT)
        && !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
        *al = SSL_AD_HANDSHAKE_FAILURE;
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT,
               SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
        return 0;
    }

    return 1;
}

int ssl_prepare_clienthello_tlsext(SSL *s)
{
# ifndef OPENSSL_NO_EC
    /*
     * If we are client and using an elliptic curve cryptography cipher
     * suite, send the point formats and elliptic curves we support.
     */
    int using_ecc = 0;
    int i;
    unsigned char *j;
    unsigned long alg_k, alg_a;
    STACK_OF(SSL_CIPHER) *cipher_stack = SSL_get_ciphers(s);

    for (i = 0; i < sk_SSL_CIPHER_num(cipher_stack); i++) {
        SSL_CIPHER *c = sk_SSL_CIPHER_value(cipher_stack, i);

        alg_k = c->algorithm_mkey;
        alg_a = c->algorithm_auth;
        if ((alg_k & (SSL_kEECDH | SSL_kECDHr | SSL_kECDHe)
             || (alg_a & SSL_aECDSA))) {
            using_ecc = 1;
            break;
        }
    }
    using_ecc = using_ecc && (s->version >= TLS1_VERSION);
    if (using_ecc) {
        if (s->tlsext_ecpointformatlist != NULL)
            OPENSSL_free(s->tlsext_ecpointformatlist);
        if ((s->tlsext_ecpointformatlist = OPENSSL_malloc(3)) == NULL) {
            SSLerr(SSL_F_SSL_PREPARE_CLIENTHELLO_TLSEXT,
                   ERR_R_MALLOC_FAILURE);
            return -1;
        }
        s->tlsext_ecpointformatlist_length = 3;
        s->tlsext_ecpointformatlist[0] = TLSEXT_ECPOINTFORMAT_uncompressed;
        s->tlsext_ecpointformatlist[1] =
            TLSEXT_ECPOINTFORMAT_ansiX962_compressed_prime;
        s->tlsext_ecpointformatlist[2] =
            TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2;

        /* we support all named elliptic curves in RFC 4492 */
        if (s->tlsext_ellipticcurvelist != NULL)
            OPENSSL_free(s->tlsext_ellipticcurvelist);
        s->tlsext_ellipticcurvelist_length =
            sizeof(pref_list) / sizeof(pref_list[0]) * 2;
        if ((s->tlsext_ellipticcurvelist =
             OPENSSL_malloc(s->tlsext_ellipticcurvelist_length)) == NULL) {
            s->tlsext_ellipticcurvelist_length = 0;
            SSLerr(SSL_F_SSL_PREPARE_CLIENTHELLO_TLSEXT,
                   ERR_R_MALLOC_FAILURE);
            return -1;
        }
        for (i = 0, j = s->tlsext_ellipticcurvelist; (unsigned int)i <
             sizeof(pref_list) / sizeof(pref_list[0]); i++) {
            int id = tls1_ec_nid2curve_id(pref_list[i]);
            s2n(id, j);
        }
    }
# endif                         /* OPENSSL_NO_EC */

# ifdef TLSEXT_TYPE_opaque_prf_input
    {
        int r = 1;

        if (s->ctx->tlsext_opaque_prf_input_callback != 0) {
            r = s->ctx->tlsext_opaque_prf_input_callback(s, NULL, 0,
                                                         s->
                                                         ctx->tlsext_opaque_prf_input_callback_arg);
            if (!r)
                return -1;
        }

        if (s->tlsext_opaque_prf_input != NULL) {
            if (s->s3->client_opaque_prf_input != NULL) {
                /* shouldn't really happen */
                OPENSSL_free(s->s3->client_opaque_prf_input);
            }

            if (s->tlsext_opaque_prf_input_len == 0) {
                /* dummy byte just to get non-NULL */
                s->s3->client_opaque_prf_input = OPENSSL_malloc(1);
            } else {
                s->s3->client_opaque_prf_input =
                    BUF_memdup(s->tlsext_opaque_prf_input,
                               s->tlsext_opaque_prf_input_len);
            }
            if (s->s3->client_opaque_prf_input == NULL) {
                SSLerr(SSL_F_SSL_PREPARE_CLIENTHELLO_TLSEXT,
                       ERR_R_MALLOC_FAILURE);
                return -1;
            }
            s->s3->client_opaque_prf_input_len =
                s->tlsext_opaque_prf_input_len;
        }

        if (r == 2)
            /*
             * at callback's request, insist on receiving an appropriate
             * server opaque PRF input
             */
            s->s3->server_opaque_prf_input_len =
                s->tlsext_opaque_prf_input_len;
    }
# endif

    return 1;
}

int ssl_prepare_serverhello_tlsext(SSL *s)
{
# ifndef OPENSSL_NO_EC
    /*
     * If we are server and using an ECC cipher suite, send the point formats
     * we support if the client sent us an ECPointsFormat extension.  Note
     * that the server is not supposed to send an EllipticCurves extension.
     */

    unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
    unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
    int using_ecc = (alg_k & (SSL_kEECDH | SSL_kECDHr | SSL_kECDHe))
        || (alg_a & SSL_aECDSA);
    using_ecc = using_ecc && (s->session->tlsext_ecpointformatlist != NULL);

    if (using_ecc) {
        if (s->tlsext_ecpointformatlist != NULL)
            OPENSSL_free(s->tlsext_ecpointformatlist);
        if ((s->tlsext_ecpointformatlist = OPENSSL_malloc(3)) == NULL) {
            SSLerr(SSL_F_SSL_PREPARE_SERVERHELLO_TLSEXT,
                   ERR_R_MALLOC_FAILURE);
            return -1;
        }
        s->tlsext_ecpointformatlist_length = 3;
        s->tlsext_ecpointformatlist[0] = TLSEXT_ECPOINTFORMAT_uncompressed;
        s->tlsext_ecpointformatlist[1] =
            TLSEXT_ECPOINTFORMAT_ansiX962_compressed_prime;
        s->tlsext_ecpointformatlist[2] =
            TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2;
    }
# endif                         /* OPENSSL_NO_EC */

    return 1;
}

int ssl_check_clienthello_tlsext_early(SSL *s)
{
    int ret = SSL_TLSEXT_ERR_NOACK;
    int al = SSL_AD_UNRECOGNIZED_NAME;

# ifndef OPENSSL_NO_EC
    /*
     * The handling of the ECPointFormats extension is done elsewhere, namely
     * in ssl3_choose_cipher in s3_lib.c.
     */
    /*
     * The handling of the EllipticCurves extension is done elsewhere, namely
     * in ssl3_choose_cipher in s3_lib.c.
     */
# endif

    if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
        ret =
            s->ctx->tlsext_servername_callback(s, &al,
                                               s->ctx->tlsext_servername_arg);
    else if (s->initial_ctx != NULL
             && s->initial_ctx->tlsext_servername_callback != 0)
        ret =
            s->initial_ctx->tlsext_servername_callback(s, &al,
                                                       s->
                                                       initial_ctx->tlsext_servername_arg);

# ifdef TLSEXT_TYPE_opaque_prf_input
    {
        /*
         * This sort of belongs into ssl_prepare_serverhello_tlsext(), but we
         * might be sending an alert in response to the client hello, so this
         * has to happen here in ssl_check_clienthello_tlsext_early().
         */

        int r = 1;

        if (s->ctx->tlsext_opaque_prf_input_callback != 0) {
            r = s->ctx->tlsext_opaque_prf_input_callback(s, NULL, 0,
                                                         s->
                                                         ctx->tlsext_opaque_prf_input_callback_arg);
            if (!r) {
                ret = SSL_TLSEXT_ERR_ALERT_FATAL;
                al = SSL_AD_INTERNAL_ERROR;
                goto err;
            }
        }

        if (s->s3->server_opaque_prf_input != NULL) {
            /* shouldn't really happen */
            OPENSSL_free(s->s3->server_opaque_prf_input);
        }
        s->s3->server_opaque_prf_input = NULL;

        if (s->tlsext_opaque_prf_input != NULL) {
            if (s->s3->client_opaque_prf_input != NULL &&
                s->s3->client_opaque_prf_input_len ==
                s->tlsext_opaque_prf_input_len) {
                /*
                 * can only use this extension if we have a server opaque PRF
                 * input of the same length as the client opaque PRF input!
                 */

                if (s->tlsext_opaque_prf_input_len == 0) {
                    /* dummy byte just to get non-NULL */
                    s->s3->server_opaque_prf_input = OPENSSL_malloc(1);
                } else {
                    s->s3->server_opaque_prf_input =
                        BUF_memdup(s->tlsext_opaque_prf_input,
                                   s->tlsext_opaque_prf_input_len);
                }
                if (s->s3->server_opaque_prf_input == NULL) {
                    ret = SSL_TLSEXT_ERR_ALERT_FATAL;
                    al = SSL_AD_INTERNAL_ERROR;
                    goto err;
                }
                s->s3->server_opaque_prf_input_len =
                    s->tlsext_opaque_prf_input_len;
            }
        }

        if (r == 2 && s->s3->server_opaque_prf_input == NULL) {
            /*
             * The callback wants to enforce use of the extension, but we
             * can't do that with the client opaque PRF input; abort the
             * handshake.
             */
            ret = SSL_TLSEXT_ERR_ALERT_FATAL;
            al = SSL_AD_HANDSHAKE_FAILURE;
        }
    }

 err:
# endif
    switch (ret) {
    case SSL_TLSEXT_ERR_ALERT_FATAL:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return -1;

    case SSL_TLSEXT_ERR_ALERT_WARNING:
        ssl3_send_alert(s, SSL3_AL_WARNING, al);
        return 1;

    case SSL_TLSEXT_ERR_NOACK:
        s->servername_done = 0;
    default:
        return 1;
    }
}

int ssl_check_clienthello_tlsext_late(SSL *s)
{
    int ret = SSL_TLSEXT_ERR_OK;
    int al;

    /*
     * If status request then ask callback what to do. Note: this must be
     * called after servername callbacks in case the certificate has
     * changed, and must be called after the cipher has been chosen because
     * this may influence which certificate is sent
     */
    if ((s->tlsext_status_type != -1) && s->ctx && s->ctx->tlsext_status_cb) {
        int r;
        CERT_PKEY *certpkey;
        certpkey = ssl_get_server_send_pkey(s);
        /* If no certificate can't return certificate status */
        if (certpkey == NULL) {
            s->tlsext_status_expected = 0;
            return 1;
        }
        /*
         * Set current certificate to one we will use so SSL_get_certificate
         * et al can pick it up.
         */
        s->cert->key = certpkey;
        r = s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg);
        switch (r) {
            /* We don't want to send a status request response */
        case SSL_TLSEXT_ERR_NOACK:
            s->tlsext_status_expected = 0;
            break;
            /* status request response should be sent */
        case SSL_TLSEXT_ERR_OK:
            if (s->tlsext_ocsp_resp)
                s->tlsext_status_expected = 1;
            else
                s->tlsext_status_expected = 0;
            break;
            /* something bad happened */
        case SSL_TLSEXT_ERR_ALERT_FATAL:
            ret = SSL_TLSEXT_ERR_ALERT_FATAL;
            al = SSL_AD_INTERNAL_ERROR;
            goto err;
        }
    } else
        s->tlsext_status_expected = 0;

 err:
    switch (ret) {
    case SSL_TLSEXT_ERR_ALERT_FATAL:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return -1;

    case SSL_TLSEXT_ERR_ALERT_WARNING:
        ssl3_send_alert(s, SSL3_AL_WARNING, al);
        return 1;

    default:
        return 1;
    }
}

int ssl_check_serverhello_tlsext(SSL *s)
{
    int ret = SSL_TLSEXT_ERR_NOACK;
    int al = SSL_AD_UNRECOGNIZED_NAME;

# ifndef OPENSSL_NO_EC
    /*
     * If we are client and using an elliptic curve cryptography cipher
     * suite, then if server returns an EC point formats lists extension it
     * must contain uncompressed.
     */
    unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
    unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
    if ((s->tlsext_ecpointformatlist != NULL)
        && (s->tlsext_ecpointformatlist_length > 0)
        && (s->session->tlsext_ecpointformatlist != NULL)
        && (s->session->tlsext_ecpointformatlist_length > 0)
        && ((alg_k & (SSL_kEECDH | SSL_kECDHr | SSL_kECDHe))
            || (alg_a & SSL_aECDSA))) {
        /* we are using an ECC cipher */
        size_t i;
        unsigned char *list;
        int found_uncompressed = 0;
        list = s->session->tlsext_ecpointformatlist;
        for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++) {
            if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
                found_uncompressed = 1;
                break;
            }
        }
        if (!found_uncompressed) {
            SSLerr(SSL_F_SSL_CHECK_SERVERHELLO_TLSEXT,
                   SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
            return -1;
        }
    }
    ret = SSL_TLSEXT_ERR_OK;
# endif                         /* OPENSSL_NO_EC */

    if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
        ret =
            s->ctx->tlsext_servername_callback(s, &al,
                                               s->ctx->tlsext_servername_arg);
    else if (s->initial_ctx != NULL
             && s->initial_ctx->tlsext_servername_callback != 0)
        ret =
            s->initial_ctx->tlsext_servername_callback(s, &al,
                                                       s->
                                                       initial_ctx->tlsext_servername_arg);

# ifdef TLSEXT_TYPE_opaque_prf_input
    if (s->s3->server_opaque_prf_input_len > 0) {
        /*
         * This case may indicate that we, as a client, want to insist on
         * using opaque PRF inputs. So first verify that we really have a
         * value from the server too.
         */

        if (s->s3->server_opaque_prf_input == NULL) {
            ret = SSL_TLSEXT_ERR_ALERT_FATAL;
            al = SSL_AD_HANDSHAKE_FAILURE;
        }

        /*
         * Anytime the server *has* sent an opaque PRF input, we need to
         * check that we have a client opaque PRF input of the same size.
         */
        if (s->s3->client_opaque_prf_input == NULL ||
            s->s3->client_opaque_prf_input_len !=
            s->s3->server_opaque_prf_input_len) {
            ret = SSL_TLSEXT_ERR_ALERT_FATAL;
            al = SSL_AD_ILLEGAL_PARAMETER;
        }
    }
# endif

    OPENSSL_free(s->tlsext_ocsp_resp);
    s->tlsext_ocsp_resp = NULL;
    s->tlsext_ocsp_resplen = -1;
    /*
     * If we've requested certificate status and we wont get one tell the
     * callback
     */
    if ((s->tlsext_status_type != -1) && !(s->tlsext_status_expected)
        && !(s->hit) && s->ctx && s->ctx->tlsext_status_cb) {
        int r;
        /*
         * Call callback with resp == NULL and resplen == -1 so callback
         * knows there is no response
         */
        r = s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg);
        if (r == 0) {
            al = SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE;
            ret = SSL_TLSEXT_ERR_ALERT_FATAL;
        }
        if (r < 0) {
            al = SSL_AD_INTERNAL_ERROR;
            ret = SSL_TLSEXT_ERR_ALERT_FATAL;
        }
    }

    switch (ret) {
    case SSL_TLSEXT_ERR_ALERT_FATAL:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return -1;

    case SSL_TLSEXT_ERR_ALERT_WARNING:
        ssl3_send_alert(s, SSL3_AL_WARNING, al);
        return 1;

    case SSL_TLSEXT_ERR_NOACK:
        s->servername_done = 0;
    default:
        return 1;
    }
}

/*-
 * Since the server cache lookup is done early on in the processing of the
 * ClientHello, and other operations depend on the result, we need to handle
 * any TLS session ticket extension at the same time.
 *
 *   session_id: points at the session ID in the ClientHello. This code will
 *       read past the end of this in order to parse out the session ticket
 *       extension, if any.
 *   len: the length of the session ID.
 *   limit: a pointer to the first byte after the ClientHello.
 *   ret: (output) on return, if a ticket was decrypted, then this is set to
 *       point to the resulting session.
 *
 * If s->tls_session_secret_cb is set then we are expecting a pre-shared key
 * ciphersuite, in which case we have no use for session tickets and one will
 * never be decrypted, nor will s->tlsext_ticket_expected be set to 1.
 *
 * Returns:
 *   -1: fatal error, either from parsing or decrypting the ticket.
 *    0: no ticket was found (or was ignored, based on settings).
 *    1: a zero length extension was found, indicating that the client supports
 *       session tickets but doesn't currently have one to offer.
 *    2: either s->tls_session_secret_cb was set, or a ticket was offered but
 *       couldn't be decrypted because of a non-fatal error.
 *    3: a ticket was successfully decrypted and *ret was set.
 *
 * Side effects:
 *   Sets s->tlsext_ticket_expected to 1 if the server will have to issue
 *   a new session ticket to the client because the client indicated support
 *   (and s->tls_session_secret_cb is NULL) but the client either doesn't have
 *   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.
 */
int tls1_process_ticket(SSL *s, unsigned char *session_id, int len,
                        const unsigned char *limit, SSL_SESSION **ret)
{
    /* Point after session ID in client hello */
    const unsigned char *p = session_id + len;
    unsigned short i;

    *ret = NULL;
    s->tlsext_ticket_expected = 0;

    /*
     * If tickets disabled behave as if no ticket present to permit stateful
     * resumption.
     */
    if (SSL_get_options(s) & SSL_OP_NO_TICKET)
        return 0;
    if ((s->version <= SSL3_VERSION) || !limit)
        return 0;
    if (p >= limit)
        return -1;
    /* Skip past DTLS cookie */
    if (s->version == DTLS1_VERSION || s->version == DTLS1_BAD_VER) {
        i = *(p++);
        p += i;
        if (p >= limit)
            return -1;
    }
    /* Skip past cipher list */
    n2s(p, i);
    p += i;
    if (p >= limit)
        return -1;
    /* Skip past compression algorithm list */
    i = *(p++);
    p += i;
    if (p > limit)
        return -1;
    /* Now at start of extensions */
    if ((p + 2) >= limit)
        return 0;
    n2s(p, i);
    while ((p + 4) <= limit) {
        unsigned short type, size;
        n2s(p, type);
        n2s(p, size);
        if (p + size > limit)
            return 0;
        if (type == TLSEXT_TYPE_session_ticket) {
            int r;
            if (size == 0) {
                /*
                 * The client will accept a ticket but doesn't currently have
                 * one.
                 */
                s->tlsext_ticket_expected = 1;
                return 1;
            }
            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;
            }
            r = tls_decrypt_ticket(s, p, size, session_id, len, ret);
            switch (r) {
            case 2:            /* ticket couldn't be decrypted */
                s->tlsext_ticket_expected = 1;
                return 2;
            case 3:            /* ticket was decrypted */
                return r;
            case 4:            /* ticket decrypted but need to renew */
                s->tlsext_ticket_expected = 1;
                return 3;
            default:           /* fatal error */
                return -1;
            }
        }
        p += size;
    }
    return 0;
}

/*-
 * tls_decrypt_ticket attempts to decrypt a session ticket.
 *
 *   etick: points to the body of the session ticket extension.
 *   eticklen: the length of the session tickets extenion.
 *   sess_id: points at the session ID.
 *   sesslen: the length of the session ID.
 *   psess: (output) on return, if a ticket was decrypted, then this is set to
 *       point to the resulting session.
 *
 * Returns:
 *   -1: fatal error, either from parsing or decrypting the ticket.
 *    2: the ticket couldn't be decrypted.
 *    3: a ticket was successfully decrypted and *psess was set.
 *    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)
{
    SSL_SESSION *sess;
    unsigned char *sdec;
    const unsigned char *p;
    int slen, mlen, renew_ticket = 0;
    unsigned char tick_hmac[EVP_MAX_MD_SIZE];
    HMAC_CTX hctx;
    EVP_CIPHER_CTX ctx;
    SSL_CTX *tctx = s->initial_ctx;
    /* Need at least keyname + iv + some encrypted data */
    if (eticklen < 48)
        return 2;
    /* Initialize session ticket encryption and HMAC contexts */
    HMAC_CTX_init(&hctx);
    EVP_CIPHER_CTX_init(&ctx);
    if (tctx->tlsext_ticket_key_cb) {
        unsigned char *nctick = (unsigned char *)etick;
        int rv = tctx->tlsext_ticket_key_cb(s, nctick, nctick + 16,
                                            &ctx, &hctx, 0);
        if (rv < 0)
            return -1;
        if (rv == 0)
            return 2;
        if (rv == 2)
            renew_ticket = 1;
    } else {
        /* Check key name matches */
        if (memcmp(etick, tctx->tlsext_tick_key_name, 16))
            return 2;
        if (HMAC_Init_ex(&hctx, tctx->tlsext_tick_hmac_key, 16,
                         tlsext_tick_md(), NULL) <= 0
                || EVP_DecryptInit_ex(&ctx, EVP_aes_128_cbc(), NULL,
                                      tctx->tlsext_tick_aes_key,
                                      etick + 16) <= 0) {
            goto err;
       }
    }
    /*
     * Attempt to process session ticket, first conduct sanity and integrity
     * checks on ticket.
     */
    mlen = HMAC_size(&hctx);
    if (mlen < 0) {
        goto err;
    }
    eticklen -= mlen;
    /* Check HMAC of encrypted ticket */
    if (HMAC_Update(&hctx, etick, eticklen) <= 0
            || HMAC_Final(&hctx, tick_hmac, NULL) <= 0) {
        goto err;
    }
    HMAC_CTX_cleanup(&hctx);
    if (CRYPTO_memcmp(tick_hmac, etick + eticklen, mlen)) {
        EVP_CIPHER_CTX_cleanup(&ctx);
        return 2;
    }
    /* Attempt to decrypt session data */
    /* Move p after IV to start of encrypted ticket, update length */
    p = etick + 16 + EVP_CIPHER_CTX_iv_length(&ctx);
    eticklen -= 16 + EVP_CIPHER_CTX_iv_length(&ctx);
    sdec = OPENSSL_malloc(eticklen);
    if (!sdec || EVP_DecryptUpdate(&ctx, sdec, &slen, p, eticklen) <= 0) {
        EVP_CIPHER_CTX_cleanup(&ctx);
        return -1;
    }
    if (EVP_DecryptFinal(&ctx, sdec + slen, &mlen) <= 0) {
        EVP_CIPHER_CTX_cleanup(&ctx);
        OPENSSL_free(sdec);
        return 2;
    }
    slen += mlen;
    EVP_CIPHER_CTX_cleanup(&ctx);
    p = sdec;

    sess = d2i_SSL_SESSION(NULL, &p, slen);
    OPENSSL_free(sdec);
    if (sess) {
        /*
         * The session ID, if non-empty, is used by some clients to detect
         * that the ticket has been accepted. So we copy it to the session
         * structure. If it is empty set length to zero as required by
         * standard.
         */
        if (sesslen)
            memcpy(sess->session_id, sess_id, sesslen);
        sess->session_id_length = sesslen;
        *psess = sess;
        if (renew_ticket)
            return 4;
        else
            return 3;
    }
    ERR_clear_error();
    /*
     * For session parse failure, indicate that we need to send a new ticket.
     */
    return 2;
err:
    EVP_CIPHER_CTX_cleanup(&ctx);
    HMAC_CTX_cleanup(&hctx);
    return -1;
}

/* Tables to translate from NIDs to TLS v1.2 ids */

typedef struct {
    int nid;
    int id;
} tls12_lookup;

static tls12_lookup tls12_md[] = {
# ifndef OPENSSL_NO_MD5
    {NID_md5, TLSEXT_hash_md5},
# endif
# ifndef OPENSSL_NO_SHA
    {NID_sha1, TLSEXT_hash_sha1},
# endif
# ifndef OPENSSL_NO_SHA256
    {NID_sha224, TLSEXT_hash_sha224},
    {NID_sha256, TLSEXT_hash_sha256},
# endif
# ifndef OPENSSL_NO_SHA512
    {NID_sha384, TLSEXT_hash_sha384},
    {NID_sha512, TLSEXT_hash_sha512}
# endif
};

static tls12_lookup tls12_sig[] = {
# ifndef OPENSSL_NO_RSA
    {EVP_PKEY_RSA, TLSEXT_signature_rsa},
# endif
# ifndef OPENSSL_NO_DSA
    {EVP_PKEY_DSA, TLSEXT_signature_dsa},
# endif
# ifndef OPENSSL_NO_ECDSA
    {EVP_PKEY_EC, TLSEXT_signature_ecdsa}
# endif
};

static int tls12_find_id(int nid, tls12_lookup *table, size_t tlen)
{
    size_t i;
    for (i = 0; i < tlen; i++) {
        if (table[i].nid == nid)
            return table[i].id;
    }
    return -1;
}

# if 0
static int tls12_find_nid(int id, tls12_lookup *table, size_t tlen)
{
    size_t i;
    for (i = 0; i < tlen; i++) {
        if (table[i].id == id)
            return table[i].nid;
    }
    return -1;
}
# endif

int tls12_get_sigandhash(unsigned char *p, const EVP_PKEY *pk,
                         const EVP_MD *md)
{
    int sig_id, md_id;
    if (!md)
        return 0;
    md_id = tls12_find_id(EVP_MD_type(md), tls12_md,
                          sizeof(tls12_md) / sizeof(tls12_lookup));
    if (md_id == -1)
        return 0;
    sig_id = tls12_get_sigid(pk);
    if (sig_id == -1)
        return 0;
    p[0] = (unsigned char)md_id;
    p[1] = (unsigned char)sig_id;
    return 1;
}

int tls12_get_sigid(const EVP_PKEY *pk)
{
    return tls12_find_id(pk->type, tls12_sig,
                         sizeof(tls12_sig) / sizeof(tls12_lookup));
}

const EVP_MD *tls12_get_hash(unsigned char hash_alg)
{
    switch (hash_alg) {
# ifndef OPENSSL_NO_SHA
    case TLSEXT_hash_sha1:
        return EVP_sha1();
# endif
# ifndef OPENSSL_NO_SHA256
    case TLSEXT_hash_sha224:
        return EVP_sha224();

    case TLSEXT_hash_sha256:
        return EVP_sha256();
# endif
# ifndef OPENSSL_NO_SHA512
    case TLSEXT_hash_sha384:
        return EVP_sha384();

    case TLSEXT_hash_sha512:
        return EVP_sha512();
# endif
    default:
        return NULL;

    }
}

/* Set preferred digest for each key type */

int tls1_process_sigalgs(SSL *s, const unsigned char *data, int dsize)
{
    int i, idx;
    const EVP_MD *md;
    CERT *c = s->cert;
    /* Extension ignored for TLS versions below 1.2 */
    if (TLS1_get_version(s) < TLS1_2_VERSION)
        return 1;
    /* Should never happen */
    if (!c)
        return 0;

    c->pkeys[SSL_PKEY_DSA_SIGN].digest = NULL;
    c->pkeys[SSL_PKEY_RSA_SIGN].digest = NULL;
    c->pkeys[SSL_PKEY_RSA_ENC].digest = NULL;
    c->pkeys[SSL_PKEY_ECC].digest = NULL;

    for (i = 0; i < dsize; i += 2) {
        unsigned char hash_alg = data[i], sig_alg = data[i + 1];

        switch (sig_alg) {
# ifndef OPENSSL_NO_RSA
        case TLSEXT_signature_rsa:
            idx = SSL_PKEY_RSA_SIGN;
            break;
# endif
# ifndef OPENSSL_NO_DSA
        case TLSEXT_signature_dsa:
            idx = SSL_PKEY_DSA_SIGN;
            break;
# endif
# ifndef OPENSSL_NO_ECDSA
        case TLSEXT_signature_ecdsa:
            idx = SSL_PKEY_ECC;
            break;
# endif
        default:
            continue;
        }

        if (c->pkeys[idx].digest == NULL) {
            md = tls12_get_hash(hash_alg);
            if (md) {
                c->pkeys[idx].digest = md;
                if (idx == SSL_PKEY_RSA_SIGN)
                    c->pkeys[SSL_PKEY_RSA_ENC].digest = md;
            }
        }

    }

    /*
     * Set any remaining keys to default values. NOTE: if alg is not
     * supported it stays as NULL.
     */
# ifndef OPENSSL_NO_DSA
    if (!c->pkeys[SSL_PKEY_DSA_SIGN].digest)
        c->pkeys[SSL_PKEY_DSA_SIGN].digest = EVP_sha1();
# endif
# ifndef OPENSSL_NO_RSA
    if (!c->pkeys[SSL_PKEY_RSA_SIGN].digest) {
        c->pkeys[SSL_PKEY_RSA_SIGN].digest = EVP_sha1();
        c->pkeys[SSL_PKEY_RSA_ENC].digest = EVP_sha1();
    }
# endif
# ifndef OPENSSL_NO_ECDSA
    if (!c->pkeys[SSL_PKEY_ECC].digest)
        c->pkeys[SSL_PKEY_ECC].digest = EVP_sha1();
# endif
    return 1;
}

#endif

#ifndef OPENSSL_NO_HEARTBEATS
int tls1_process_heartbeat(SSL *s)
{
    unsigned char *p = &s->s3->rrec.data[0], *pl;
    unsigned short hbtype;
    unsigned int payload;
    unsigned int padding = 16;  /* Use minimum padding */

    if (s->msg_callback)
        s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
                        &s->s3->rrec.data[0], s->s3->rrec.length,
                        s, s->msg_callback_arg);

    /* Read type and payload length first */
    if (1 + 2 + 16 > s->s3->rrec.length)
        return 0;               /* silently discard */
    hbtype = *p++;
    n2s(p, payload);
    if (1 + 2 + payload + 16 > s->s3->rrec.length)
        return 0;               /* silently discard per RFC 6520 sec. 4 */
    pl = p;

    if (hbtype == TLS1_HB_REQUEST) {
        unsigned char *buffer, *bp;
        int r;

        /*
         * Allocate memory for the response, size is 1 bytes message type,
         * plus 2 bytes payload length, plus payload, plus padding
         */
        buffer = OPENSSL_malloc(1 + 2 + payload + padding);
        bp = buffer;

        /* Enter response type, length and copy payload */
        *bp++ = TLS1_HB_RESPONSE;
        s2n(payload, bp);
        memcpy(bp, pl, payload);
        bp += payload;
        /* Random padding */
        if (RAND_pseudo_bytes(bp, padding) < 0) {
            OPENSSL_free(buffer);
            return -1;
        }

        r = ssl3_write_bytes(s, TLS1_RT_HEARTBEAT, buffer,
                             3 + payload + padding);

        if (r >= 0 && s->msg_callback)
            s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
                            buffer, 3 + payload + padding,
                            s, s->msg_callback_arg);

        OPENSSL_free(buffer);

        if (r < 0)
            return r;
    } else if (hbtype == TLS1_HB_RESPONSE) {
        unsigned int seq;

        /*
         * We only send sequence numbers (2 bytes unsigned int), and 16
         * random bytes, so we just try to read the sequence number
         */
        n2s(pl, seq);

        if (payload == 18 && seq == s->tlsext_hb_seq) {
            s->tlsext_hb_seq++;
            s->tlsext_hb_pending = 0;
        }
    }

    return 0;
}

int tls1_heartbeat(SSL *s)
{
    unsigned char *buf, *p;
    int ret = -1;
    unsigned int payload = 18;  /* Sequence number + random bytes */
    unsigned int padding = 16;  /* Use minimum padding */

    /* Only send if peer supports and accepts HB requests... */
    if (!(s->tlsext_heartbeat & SSL_TLSEXT_HB_ENABLED) ||
        s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_SEND_REQUESTS) {
        SSLerr(SSL_F_TLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
        return -1;
    }

    /* ...and there is none in flight yet... */
    if (s->tlsext_hb_pending) {
        SSLerr(SSL_F_TLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PENDING);
        return -1;
    }

    /* ...and no handshake in progress. */
    if (SSL_in_init(s) || s->in_handshake) {
        SSLerr(SSL_F_TLS1_HEARTBEAT, SSL_R_UNEXPECTED_MESSAGE);
        return -1;
    }

    /*
     * Check if padding is too long, payload and padding must not exceed 2^14
     * - 3 = 16381 bytes in total.
     */
    OPENSSL_assert(payload + padding <= 16381);

    /*-
     * Create HeartBeat message, we just use a sequence number
     * as payload to distuingish different messages and add
     * some random stuff.
     *  - Message Type, 1 byte
     *  - Payload Length, 2 bytes (unsigned int)
     *  - Payload, the sequence number (2 bytes uint)
     *  - Payload, random bytes (16 bytes uint)
     *  - Padding
     */
    buf = OPENSSL_malloc(1 + 2 + payload + padding);
    p = buf;
    /* Message Type */
    *p++ = TLS1_HB_REQUEST;
    /* Payload length (18 bytes here) */
    s2n(payload, p);
    /* Sequence number */
    s2n(s->tlsext_hb_seq, p);
    /* 16 random bytes */
    if (RAND_pseudo_bytes(p, 16) < 0) {
        SSLerr(SSL_F_TLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
        goto err;
    }
    p += 16;
    /* Random padding */
    if (RAND_pseudo_bytes(p, padding) < 0) {
        SSLerr(SSL_F_TLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
        goto err;
    }

    ret = ssl3_write_bytes(s, TLS1_RT_HEARTBEAT, buf, 3 + payload + padding);
    if (ret >= 0) {
        if (s->msg_callback)
            s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
                            buf, 3 + payload + padding,
                            s, s->msg_callback_arg);

        s->tlsext_hb_pending = 1;
    }

err:
    OPENSSL_free(buf);

    return ret;
}
#endif