Commit 50932c4a authored by Matt Caswell's avatar Matt Caswell
Browse files

PACKETise ServerHello processing



Process ServerHello messages using the PACKET API

Reviewed-by: default avatarTim Hudson <tjh@openssl.org>
parent 0e2d0911
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+9 −15
Original line number Diff line number Diff line
@@ -358,33 +358,27 @@ int ssl_add_serverhello_use_srtp_ext(SSL *s, unsigned char *p, int *len,
    return 0;
}

int ssl_parse_serverhello_use_srtp_ext(SSL *s, unsigned char *d, int len,
                                       int *al)
int ssl_parse_serverhello_use_srtp_ext(SSL *s, PACKET *pkt, int *al)
{
    unsigned id;
    unsigned int id, ct, mki;
    int i;
    int ct;

    STACK_OF(SRTP_PROTECTION_PROFILE) *clnt;
    SRTP_PROTECTION_PROFILE *prof;

    if (len != 5) {
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_USE_SRTP_EXT,
               SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
        *al = SSL_AD_DECODE_ERROR;
        return 1;
    }

    n2s(d, ct);
    if (ct != 2) {
    if (!PACKET_get_net_2(pkt, &ct)
            || ct != 2
            || !PACKET_get_net_2(pkt, &id)
            || !PACKET_get_1(pkt, &mki)
            || PACKET_remaining(pkt) != 0) {
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_USE_SRTP_EXT,
               SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
        *al = SSL_AD_DECODE_ERROR;
        return 1;
    }

    n2s(d, id);
    if (*d) {                   /* Must be no MKI, since we never offer one */
    if (mki != 0) {
        /* Must be no MKI, since we never offer one */
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_USE_SRTP_EXT,
               SSL_R_BAD_SRTP_MKI_VALUE);
        *al = SSL_AD_ILLEGAL_PARAMETER;
+88 −28
Original line number Diff line number Diff line
@@ -930,9 +930,10 @@ int ssl3_get_server_hello(SSL *s)
{
    STACK_OF(SSL_CIPHER) *sk;
    const SSL_CIPHER *c;
    unsigned char *p, *d;
    PACKET pkt;
    unsigned char *session_id, *cipherchars;
    int i, al = SSL_AD_INTERNAL_ERROR, ok;
    unsigned int j;
    unsigned int j, ciphercharlen;
    long n;
#ifndef OPENSSL_NO_COMP
    SSL_COMP *comp;
@@ -971,10 +972,20 @@ int ssl3_get_server_hello(SSL *s)
        goto f_err;
    }

    d = p = (unsigned char *)s->init_msg;
    if (!PACKET_buf_init(&pkt, s->init_msg, n)) {
        al = SSL_AD_INTERNAL_ERROR;
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, ERR_R_INTERNAL_ERROR);
        goto f_err;
    }

    if (s->method->version == TLS_ANY_VERSION) {
        int sversion = (p[0] << 8) | p[1];
        unsigned int sversion;

        if (!PACKET_get_net_2(&pkt, &sversion)) {
            al = SSL_AD_DECODE_ERROR;
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
            goto f_err;
        }

#if TLS_MAX_VERSION != TLS1_2_VERSION
#error Code needs updating for new TLS version
@@ -1012,8 +1023,16 @@ int ssl3_get_server_hello(SSL *s)
        }
    } else if (s->method->version == DTLS_ANY_VERSION) {
        /* Work out correct protocol version to use */
        int hversion = (p[0] << 8) | p[1];
        int options = s->options;
        unsigned int hversion;
        int options;

        if (!PACKET_get_net_2(&pkt, &hversion)) {
            al = SSL_AD_DECODE_ERROR;
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
            goto f_err;
        }

        options = s->options;
        if (hversion == DTLS1_2_VERSION && !(options & SSL_OP_NO_DTLSv1_2))
            s->method = DTLSv1_2_client_method();
        else if (tls1_suiteb(s)) {
@@ -1031,30 +1050,43 @@ int ssl3_get_server_hello(SSL *s)
            goto f_err;
        }
        s->session->ssl_version = s->version = s->method->version;
    } else if ((p[0] != (s->version >> 8)) || (p[1] != (s->version & 0xff))) {
    } else {
        unsigned char *vers;

        if (!PACKET_get_bytes(&pkt, &vers, 2)) {
            al = SSL_AD_DECODE_ERROR;
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
            goto f_err;
        }
        if ((vers[0] != (s->version >> 8))
                || (vers[1] != (s->version & 0xff))) {
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_WRONG_SSL_VERSION);
        s->version = (s->version & 0xff00) | p[1];
            s->version = (s->version & 0xff00) | vers[1];
            al = SSL_AD_PROTOCOL_VERSION;
            goto f_err;
        }
    p += 2;
    }

    /* load the server hello data */
    /* load the server random */
    memcpy(s->s3->server_random, p, SSL3_RANDOM_SIZE);
    p += SSL3_RANDOM_SIZE;
    if (!PACKET_copy_bytes(&pkt, s->s3->server_random, SSL3_RANDOM_SIZE)) {
        al = SSL_AD_DECODE_ERROR;
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
        goto f_err;
    }

    s->hit = 0;

    /* get the session-id */
    j = *(p++);

    if ((j > sizeof s->session->session_id) || (j > SSL3_SESSION_ID_SIZE)) {
    /* get the session-id length */
    if (!PACKET_get_1(&pkt, &j)
            || (j > sizeof s->session->session_id)
            || (j > SSL3_SESSION_ID_SIZE)) {
        al = SSL_AD_ILLEGAL_PARAMETER;
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_SSL3_SESSION_ID_TOO_LONG);
        goto f_err;
    }

    ciphercharlen = ssl_put_cipher_by_char(s, NULL, NULL);
    /*
     * Check if we can resume the session based on external pre-shared secret.
     * EAP-FAST (RFC 4851) supports two types of session resumption.
@@ -1070,22 +1102,42 @@ int ssl3_get_server_hello(SSL *s)
    if (s->version >= TLS1_VERSION && s->tls_session_secret_cb &&
        s->session->tlsext_tick) {
        SSL_CIPHER *pref_cipher = NULL;
        size_t bookm;
        if (!PACKET_get_bookmark(&pkt, &bookm)
                || !PACKET_forward(&pkt, j)
                || !PACKET_get_bytes(&pkt, &cipherchars, ciphercharlen)) {
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
            al = SSL_AD_DECODE_ERROR;
            goto f_err;
        }
        s->session->master_key_length = sizeof(s->session->master_key);
        if (s->tls_session_secret_cb(s, s->session->master_key,
                                     &s->session->master_key_length,
                                     NULL, &pref_cipher,
                                     s->tls_session_secret_cb_arg)) {
            s->session->cipher = pref_cipher ?
                pref_cipher : ssl_get_cipher_by_char(s, p + j);
                pref_cipher : ssl_get_cipher_by_char(s, cipherchars);
        } else {
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, ERR_R_INTERNAL_ERROR);
            al = SSL_AD_INTERNAL_ERROR;
            goto f_err;
        }
        if (!PACKET_goto_bookmark(&pkt, bookm)) {
            SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, ERR_R_INTERNAL_ERROR);
            al = SSL_AD_INTERNAL_ERROR;
            goto f_err;
        }
    }

    /* Get the session id */
    if (!PACKET_get_bytes(&pkt, &session_id, j)) {
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
        al = SSL_AD_DECODE_ERROR;
        goto f_err;
    }

    if (j != 0 && j == s->session->session_id_length
        && memcmp(p, s->session->session_id, j) == 0) {
        && memcmp(session_id, s->session->session_id, j) == 0) {
        if (s->sid_ctx_length != s->session->sid_ctx_length
            || memcmp(s->session->sid_ctx, s->sid_ctx, s->sid_ctx_length)) {
            /* actually a client application bug */
@@ -1109,10 +1161,15 @@ int ssl3_get_server_hello(SSL *s)
            }
        }
        s->session->session_id_length = j;
        memcpy(s->session->session_id, p, j); /* j could be 0 */
        memcpy(s->session->session_id, session_id, j); /* j could be 0 */
    }
    p += j;
    c = ssl_get_cipher_by_char(s, p);

    if (!PACKET_get_bytes(&pkt, &cipherchars, ciphercharlen)) {
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
        al = SSL_AD_DECODE_ERROR;
        goto f_err;
    }
    c = ssl_get_cipher_by_char(s, cipherchars);
    if (c == NULL) {
        /* unknown cipher */
        al = SSL_AD_ILLEGAL_PARAMETER;
@@ -1133,7 +1190,6 @@ int ssl3_get_server_hello(SSL *s)
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_WRONG_CIPHER_RETURNED);
        goto f_err;
    }
    p += ssl_put_cipher_by_char(s, NULL, NULL);

    sk = ssl_get_ciphers_by_id(s);
    i = sk_SSL_CIPHER_find(sk, c);
@@ -1166,8 +1222,13 @@ int ssl3_get_server_hello(SSL *s)
        goto f_err;
    /* lets get the compression algorithm */
    /* COMPRESSION */
    if (!PACKET_get_1(&pkt, &j)) {
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_LENGTH_MISMATCH);
        al = SSL_AD_DECODE_ERROR;
        goto f_err;
    }
#ifdef OPENSSL_NO_COMP
    if (*(p++) != 0) {
    if (j != 0) {
        al = SSL_AD_ILLEGAL_PARAMETER;
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO,
               SSL_R_UNSUPPORTED_COMPRESSION_ALGORITHM);
@@ -1182,7 +1243,6 @@ int ssl3_get_server_hello(SSL *s)
        goto f_err;
    }
#else
    j = *(p++);
    if (s->hit && j != s->session->compress_meth) {
        al = SSL_AD_ILLEGAL_PARAMETER;
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO,
@@ -1209,12 +1269,12 @@ int ssl3_get_server_hello(SSL *s)
#endif

    /* TLS extensions */
    if (!ssl_parse_serverhello_tlsext(s, &p, d, n)) {
    if (!ssl_parse_serverhello_tlsext(s, &pkt)) {
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_PARSE_TLSEXT);
        goto err;
    }

    if (p != (d + n)) {
    if (PACKET_remaining(&pkt) != 0) {
        /* wrong packet length */
        al = SSL_AD_DECODE_ERROR;
        SSLerr(SSL_F_SSL3_GET_SERVER_HELLO, SSL_R_BAD_PACKET_LENGTH);
+3 −5
Original line number Diff line number Diff line
@@ -2088,8 +2088,7 @@ __owur unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
__owur int ssl_parse_clienthello_tlsext(SSL *s, PACKET *pkt);
__owur int tls1_set_server_sigalgs(SSL *s);
__owur int ssl_check_clienthello_tlsext_late(SSL *s);
__owur int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **data,
                                 unsigned char *d, int n);
__owur int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt);
__owur int ssl_prepare_clienthello_tlsext(SSL *s);
__owur int ssl_prepare_serverhello_tlsext(SSL *s);

@@ -2126,7 +2125,7 @@ __owur EVP_MD_CTX *ssl_replace_hash(EVP_MD_CTX **hash, const EVP_MD *md);
void ssl_clear_hash_ctx(EVP_MD_CTX **hash);
__owur int ssl_add_serverhello_renegotiate_ext(SSL *s, unsigned char *p, int *len,
                                        int maxlen);
__owur int ssl_parse_serverhello_renegotiate_ext(SSL *s, unsigned char *d, int len,
__owur int ssl_parse_serverhello_renegotiate_ext(SSL *s, PACKET *pkt,
                                          int *al);
__owur int ssl_add_clienthello_renegotiate_ext(SSL *s, unsigned char *p, int *len,
                                        int maxlen);
@@ -2147,8 +2146,7 @@ __owur int ssl_add_clienthello_use_srtp_ext(SSL *s, unsigned char *p, int *len,
__owur int ssl_parse_clienthello_use_srtp_ext(SSL *s, PACKET *pkt, int *al);
__owur int ssl_add_serverhello_use_srtp_ext(SSL *s, unsigned char *p, int *len,
                                     int maxlen);
__owur int ssl_parse_serverhello_use_srtp_ext(SSL *s, unsigned char *d, int len,
                                       int *al);
__owur int ssl_parse_serverhello_use_srtp_ext(SSL *s, PACKET *pkt, int *al);

__owur int ssl_handshake_hash(SSL *s, unsigned char *out, int outlen);

+45 −54
Original line number Diff line number Diff line
@@ -2344,28 +2344,23 @@ int ssl_parse_clienthello_tlsext(SSL *s, PACKET *pkt)
 * 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)
static char ssl_next_proto_validate(PACKET *pkt)
{
    unsigned int off = 0;
    unsigned int len;

    while (off < len) {
        if (d[off] == 0)
    while (PACKET_remaining(pkt)) {
        if (!PACKET_get_1(pkt, &len)
                || !PACKET_forward(pkt, len))
            return 0;
        off += d[off];
        off++;
    }

    return off == len;
    return 1;
}
#endif

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

@@ -2385,27 +2380,27 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
    s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
#endif

    if (data >= (d + n - 2))
    if (!PACKET_get_net_2(pkt, &length))
        goto ri_check;

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

    while (data <= (d + n - 4)) {
        n2s(data, type);
        n2s(data, size);
    while (PACKET_get_net_2(pkt, &type) && PACKET_get_net_2(pkt, &size)) {
        unsigned char *data;
        PACKET spkt;

        if (data + size > (d + n))
        if (!PACKET_get_sub_packet(pkt, &spkt, size)
                ||  !PACKET_peek_bytes(&spkt, &data, size))
            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_renegotiate) {
            if (!ssl_parse_serverhello_renegotiate_ext(s, data, size, al))
            if (!ssl_parse_serverhello_renegotiate_ext(s, &spkt, al))
                return 0;
            renegotiate_seen = 1;
        } else if (s->version == SSL3_VERSION) {
@@ -2418,10 +2413,9 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
        }
#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) {
            unsigned int ecpointformatlist_length;
            if (!PACKET_get_1(&spkt, &ecpointformatlist_length)
                    || ecpointformatlist_length != size - 1) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
@@ -2435,8 +2429,13 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
                }
                s->session->tlsext_ecpointformatlist_length =
                    ecpointformatlist_length;
                memcpy(s->session->tlsext_ecpointformatlist, sdata,
                       ecpointformatlist_length);
                if (!PACKET_copy_bytes(&spkt,
                                       s->session->tlsext_ecpointformatlist,
                                       ecpointformatlist_length)) {
                    *al = TLS1_AD_DECODE_ERROR;
                    return 0;
                }

            }
        }
#endif                         /* OPENSSL_NO_EC */
@@ -2472,14 +2471,13 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
                 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)) {
            if (!ssl_next_proto_validate(&spkt)) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
@@ -2504,31 +2502,21 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,

        else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation) {
            unsigned len;

            /* We must have requested it. */
            if (s->alpn_client_proto_list == NULL) {
                *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                return 0;
            }
            if (size < 4) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
            /*-
             * The extension data consists of:
             *   uint16 list_length
             *   uint8 proto_length;
             *   uint8 proto[proto_length];
             */
            len = data[0];
            len <<= 8;
            len |= data[1];
            if (len != (unsigned)size - 2) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
            len = data[2];
            if (len != (unsigned)size - 3) {
            if (!PACKET_get_net_2(&spkt, &len)
                    || PACKET_remaining(&spkt) != len
                    || !PACKET_get_1(&spkt, &len)
                    || PACKET_remaining(&spkt) != len) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
@@ -2538,12 +2526,20 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
                *al = TLS1_AD_INTERNAL_ERROR;
                return 0;
            }
            memcpy(s->s3->alpn_selected, data + 3, len);
            if (!PACKET_copy_bytes(&spkt, s->s3->alpn_selected, len)) {
                *al = TLS1_AD_DECODE_ERROR;
                return 0;
            }
            s->s3->alpn_selected_len = len;
        }
#ifndef OPENSSL_NO_HEARTBEATS
        else if (type == TLSEXT_TYPE_heartbeat) {
            switch (data[0]) {
            unsigned int hbtype;
            if (!PACKET_get_1(&spkt, &hbtype)) {
                *al = SSL_AD_DECODE_ERROR;
                return 0;
            }
            switch (hbtype) {
            case 0x01:         /* Server allows us to send HB requests */
                s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                break;
@@ -2559,7 +2555,7 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
#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))
            if (ssl_parse_serverhello_use_srtp_ext(s, &spkt, al))
                return 0;
        }
#endif
@@ -2581,11 +2577,9 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
         */
        else if (custom_ext_parse(s, 0, type, data, size, al) <= 0)
            return 0;

        data += size;
    }

    if (data != d + n) {
    if (PACKET_remaining(pkt) != 0) {
        *al = SSL_AD_DECODE_ERROR;
        return 0;
    }
@@ -2605,8 +2599,6 @@ static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
        }
    }

    *p = data;

 ri_check:

    /*
@@ -2887,13 +2879,12 @@ int ssl_check_serverhello_tlsext(SSL *s)
    }
}

int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
                                 int n)
int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt)
{
    int al = -1;
    if (s->version < SSL3_VERSION)
        return 1;
    if (ssl_scan_serverhello_tlsext(s, p, d, n, &al) <= 0) {
    if (ssl_scan_serverhello_tlsext(s, pkt, &al) <= 0) {
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return 0;
    }
+12 −13
Original line number Diff line number Diff line
@@ -220,29 +220,27 @@ int ssl_add_serverhello_renegotiate_ext(SSL *s, unsigned char *p, int *len,
/*
 * Parse the server's renegotiation binding and abort if it's not right
 */
int ssl_parse_serverhello_renegotiate_ext(SSL *s, unsigned char *d, int len,
                                          int *al)
int ssl_parse_serverhello_renegotiate_ext(SSL *s, PACKET *pkt, int *al)
{
    int expected_len = s->s3->previous_client_finished_len
    unsigned int expected_len = s->s3->previous_client_finished_len
        + s->s3->previous_server_finished_len;
    int ilen;
    unsigned int ilen;
    unsigned char *data;

    /* Check for logic errors */
    OPENSSL_assert(!expected_len || s->s3->previous_client_finished_len);
    OPENSSL_assert(!expected_len || s->s3->previous_server_finished_len);

    /* Parse the length byte */
    if (len < 1) {
    if (!PACKET_get_1(pkt, &ilen)) {
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_RENEGOTIATE_EXT,
               SSL_R_RENEGOTIATION_ENCODING_ERR);
        *al = SSL_AD_ILLEGAL_PARAMETER;
        return 0;
    }
    ilen = *d;
    d++;

    /* Consistency check */
    if (ilen + 1 != len) {
    if (PACKET_remaining(pkt) != ilen) {
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_RENEGOTIATE_EXT,
               SSL_R_RENEGOTIATION_ENCODING_ERR);
        *al = SSL_AD_ILLEGAL_PARAMETER;
@@ -257,17 +255,18 @@ int ssl_parse_serverhello_renegotiate_ext(SSL *s, unsigned char *d, int len,
        return 0;
    }

    if (memcmp(d, s->s3->previous_client_finished,
               s->s3->previous_client_finished_len)) {
    if (!PACKET_get_bytes(pkt, &data, s->s3->previous_client_finished_len)
            || memcmp(data, s->s3->previous_client_finished,
               s->s3->previous_client_finished_len) != 0) {
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_RENEGOTIATE_EXT,
               SSL_R_RENEGOTIATION_MISMATCH);
        *al = SSL_AD_HANDSHAKE_FAILURE;
        return 0;
    }
    d += s->s3->previous_client_finished_len;

    if (memcmp(d, s->s3->previous_server_finished,
               s->s3->previous_server_finished_len)) {
    if (!PACKET_get_bytes(pkt, &data, s->s3->previous_server_finished_len)
            || memcmp(data, s->s3->previous_server_finished,
               s->s3->previous_server_finished_len) != 0) {
        SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_RENEGOTIATE_EXT,
               SSL_R_RENEGOTIATION_MISMATCH);
        *al = SSL_AD_ILLEGAL_PARAMETER;